professor niyogi bio notes

8/7/2019 Professor Niyogi Bio Notes

1/54

Niyogi NotesI suggest looking at pdfs while reading this. Shit gets real.

Lectures 1-3

Slide 1Origin of Life

-

Little gravity (H2and He)- 1statmosphere (earth formed 4.6 billion years ago)- Gravity- Atmosphere (N2& O221%)

First billion years- Too hot to allow water to accumulate on surface- Primitive earth (no life)

Abiotic synthesisformation [slow] of organic molecules = prebiotic soup

Slide 2Changes in earths atmosphere (gases)Possibly H2and He (First Atmosphere)- Earths gravity not strong enough to hold to these light gases)

H2O4, CO4, SO2, CO, S2, C12, N2, H2, NH3[ammonia] and CH4[methane]- Gases produced by volcanic activity- Earths gravity changed; gases retained- But no free O2(from volcanoes)- Earth cooled; H2O vapour condensedOcean formed

Slide 3(Same as slide 2)But O2 increased from ~2.3 billion years ago Why?

Slide 4Origin of life on earth

(1) Living cells are complex collections of molecules & macromolecules- DNA stores the information for the amino acid sequence of proteins- RNA acts as the intermediary in the process of protein synthesis- Proteins form the foundation for the structure and activities of living cells

(2) Life requires the interplay betweenDNA, RNA and proteins for its existence &perpetuation

- Given this, scientists interested in the origin of life on earth have focused theirattention on the formation of these main molecules and their building blocks(nucleotides & amino acids)


2/54

Slide 5Origin of life on earth process of 4 overlapping stagesStage 1. Origin of organic molecules (nucleotides & amino acids)

Several hypotheses:y Reducing atmosphere hypothesis (Miller & Urey 1950s)y Extraterrestrial hypothesismeteoritesy Deep sea vents hypothesis (Wachtershauser 1988)

o Mixing created conditionStage 2. Nucleotides & amino acids became polymerized to formDNA, RNA & proteins (i.e.simple organic molecules became more complex) = polymersy Did not take place in prebiotic soup but on solid surface (clay) or tidal pool

Slide 6Stage 3. Polymers became enclosed in membranes- Formation of a boundary that separated the environment from the internal polymers =

protobiont (non-living0 4 characteristics

1. Membrane (e.g. lipid bilayers) separating external environment from internalcontents

2. Polymers inside contain information3. Polymers inside had enzymatic function4. Capable of replication

Slide 7Stage 4. Polymers enclosed in membranes evolved cellular properties- Self replication and metabolism

First primitive organisms (3.8-3.5 billion years ago)

Slide 8First organisms: Prokaryotes, single-celled microorganisms living in an environment withlittle free O2in the earths atmosphere- Therefore used only anaerobic (without oxygen) metabolism

Hypothesized that first organisms were:Anaerobic heterotrophs because simplest for primitive cells to use organic molecules inprebiotic soup as a source of food than to have metabolic pathways to use energy to makeorganic molecules (i.e. like autotrophs)

y Probably heat-resistant, as ocean were continuously heated by heavy impacts ofmeteorites


3/54

y E.g. like extreme haplophiles?

Slide 91. Anaerobic heterotrophs (prokaryotes)

yMetabolized pre-existing organic molecules by fermentation or methanogenesis2C6H12O6(glucose)2 C2H5OH (ethanol) + 2 CO2+ energy (2 units)

o Modern heterotrophs are mostly aerobic eukaryotes that metabolizepre-existing organic molecules by oxidation

C6H12O6(glucose) + 6 CO26 H2O + 6 CO2+ energy (36 units)y As the organic molecules in prebiotic soup were made very slowly, the anaerobic

heterotrophs would have gradually exhausted the supply of these organicmolecules

y Therefore cells that evolved the ability to synthesize organic molecules fromthe inorganic sources would have had a growth advantage

Slide 102. Anaerobic autotrophs-chemoautotrophs & photoheterotrophs

6 CO2+ 6 CH2SC6H12O6(glucose) + 6 S (no free oxygen) Purple sulphur bacteriaCO2+ 4H2CH4+ 4 H2O Purple non-sulphur bacteria

y Hydrogen donors quickly used upy As this energy ran low, evolved ability to capture energy from light from near the

surface of the ocean photoautotrophsy This key innovation (oxygen-forming photosynthesis) around 2.5 billion years used

H2O as hydrogen donor

Photosynthesis6 CO2+ 6 H2OC6H12O6(glucose) + 6 O2(lots of free oxygen)

Slide 11Aerobic Autotrophs-photoautotrophs (prokaryotes)

= cyanobacteriaPhotosynthesis6 CO2+ 6 H2OC6H12O6(glucose) + 6 O2(lots of free oxygen)

- CO2caused crisis as huge amounts of toxic O2released- Oxygen is poisonous for anaerobic purple bacteria- Surviving anaerobic bacteria lived or moved to underground locations (site of modern

anaerobic microbes)

Slide 12Early Life- Stromatolites


4/54

o Microbially mediated rocks- Community of microbes forms mats & secretes a mucus that traps sedimentary grains,

cementing them into layers. Because the upper part of the mat requires sunlight forphotosynthesis, the mat migrates upwards, leaving the layers.

Slide 13Canada has 3 of the worlds known examples at:

Red Lake, OntarioSteep Rock Lake, OntarioNear Yellowknife, Northwest Territories

Slide 14Modern stromatolites at Shark Bay (Western Australia)y Generally found in hot or hyper-saline environments (tolerated by cyanobacteria)

because as a consequence there are few grazing or burrowing animalsy In Shark Bay; estimated 3 billion individuals/m2of mat (stromatolites up to 1.5 meters

high)

Slide 15Diagram of cyanobacteriaPhotosynthesis6 CO2+ 6 H2OC6H12O6(glucose) + 6 O2

Diagram of concentration of various atmospheric gases (percent) vs. Time

- O2 increased from ~ 2.3 billion years ago

Slide 16Early aerobic photoautotrophs present 3 3.5 billion years ago

1. Produced organic molecules from CO2prevented depletion of organic food stuffsthat would have been exhausted if there were only heterotrophs

2. Produced O2as waste product of p/s (higher atmospheric O2from ~ 2.3 billion yearsago)o Reduced the number of anaerobic b/c they need an environment lower depleted

of O2o Played key role in eukaryotic evolution (origin of first eukaryotic cell is a

matter of debate)

Slide 17CambrianExplosion (Diagram of origin from symbiotic relationship and endosymbioticrelationship)


5/54

Slide 18Significant events in the geologic time scaleEon ~million years before present

Phanerozoic Appearance of most animal groups 543

First Multicellular organisms 1500Proterozoic

Etc.

- Everything before Phanerozoic is Precambrian

Slide 19Geological Time Scaley Major ecological events (incl. positions of continents), the nature of the climate & types

of organisms presenty 4Eons; 1st3 = Precambriany Zoic = animals

Slide 20*See diagram- Mass extinctions

Slide 21*Diagram

Slide 22Changing environmentsdifferent organisms (based on fossil record)- Recurring pattern seen in history of life in the emergence of new species and

extinction of other species

Slide 23Extinction (disappearance of species)- (Pre-human) correlated with major environmental changes:

o Climate/temperatureo Atmosphereo Landmasseso Floods


6/54

o Glaciationo Volcanic eruptionso Meteorite impacts

- One or more of these variables can lead to mass extinctions

Slide 24What isExtinction?Definition: No longer in existence

End of an organism / speciesOpposite to speciation

y It occurs when the last existing member of a species dies, i.e. there arent any left!y It is a scientific certainty when there are not any surviving individuals left to

reproducey FunctionalExtinction

o Only a reduced number of individuals are lefto Population no longer viable odds of reproduction are slim

Slide 25MassExtinction

y Aka: an extinction eventy The loss of a large number of species onEarth in a short period of timey Coincides with a sharp drop in speciation

o The process by which new biological species arisey There have been at least FIVEmajor extinctions

o Last one was 65 M years ago

Slide 26MassExtinction

y Nearly 2/3rds (or more) of all animal species that ever existed on the planet arenow gone.

o With contemporary extinction being attributed to HUMAN activity.y Numerous factors go into the extinction of a specific species

o Climate change as main factor

Slide 27Natural average extinction rateBackground extinction rate rate of species loss in the absence o human activities

Fossil record: species survive 1-10 million years


7/54

Extrapolating across geologic time the average extinction rate is about 9% of species permillion years.

Average extinction rate are estimated: 1 to 10 species/5 years

Current extinction rates:It is believed that human activity has increased this rate by a factor of: 1 000 10 000times

Since 1600, approx. 1 000 species have become extinct

Slide 28G.G. Simpson 99% species originating 542 mya are extinct!

y Survivors Lingula marine organism (brachiopod) occupying certical burrows insand and mud has survived morphologically unchanged since the Silurian (450 mya)

Slide 29Survivors No. 2 A living fossilThe horseshoe crab (Limulus polyphemus), an arthropod inhabitant of marine shores, haslived morphologically uncanged since the Ordovician (est. 480 mya)

Slide 305 Mass extinctions*Diagram

Slide 31*DiagramMesozoic Tetrapods Ancestors and SurivorsTogether, the Ornithischia plus the Saurischia constitute the dinosaurs. Notice that birdsand mammals are early contemporaries of the dinosaurs.

Slide 32Jurassic

Solnhofen lagoonArchaeopteryx

Rise of Angiosperms?

Cretaceous Landscape

- Herbivores couldnt adapt to new composition of the plants


8/54

- CO2 in atmosphere was about 12x higher than today

Slide 33ca. 65 million years ago

Cosmic collisionsAt the end of the Cretaceous, an asteroid or comet struck theEarth in the location ofpresent day Yucatan Peninsula in Mexico. Although such a collision certainly occurred, it isdebated whether or not this collision was directly responsible for the dinosaur extinctions.

Slide 34FirstEvidence of a large meteor impactAbundance of RareEarthElements (REE) in K-T layer

y 1980 Luis and Walter Alvarez proposed that an impact could be identified byunusual accumulations ofrare earth elements = Alvarez Asteroid Impact Theoryy Iridium Anomaly Ir is a siderophile (binds iron_ that is a characteristic of mantle

material and is also found in cometsy Chondritic meteors are common typecontain Ir and Cry Layer of Ir-enriched rock and shocked quartz (parallel planes) is found worldwide,

and is thicker closer to the Yucatan peninsula

Slide 35Shocked quartz grains from the K-T boundary in Wyoming

y Caused by sheer impact of collision of asteroidy Supports asteroid theory

Shocked quartz is a form of quartz that has a microscopic structure that is different fromnormal quartz. Under intense pressure, the crystalline structure of quartz will be deformedalong planes inside the crystal. These planes, which show up as lines under a microscope, arecalled planar deformation features (PDFs), or shock lamellae.

Slide 36Effects of Impact

100 000 km/hr impactDestroyed life in a 500 km radius180 km diam. CraterVolcanic activities/chem. ReactionsTidal wavesIncreased tempsFires, acid rains


9/54

Slide 37Dust atmosphere darkness / Cooling

Slide 38Other changes during the KTy High sea levels general dryingy Dinosaurs may have already been under strong negative selection pressure

Slide 39The Chicxulub impact hit the Yucatan about 300 000 years before the mass extinctionthat included the dinosaurs and therefore could not have caused it, Keller says

Slide 40Mesozoic Tetrapods - Ancestors and SurvivorsTogether, the Ornithischia plus the Saurischia constitute the dinosaurs. Notice that birdsand mammals are early contemporaries of the dinosaurs.

Slide 41After the dinosaursExtinction of the dinosaurs left may ecological niches empty. In part, the subsequentflourishing of mammals and birds represents and adaptive radiation into many of thesevacated life styles.

- Mass extinctions helped other groups to diversify over time despite killing off otherdiverse organisms.

Additional Notes for Lecture 1-3

Slide 1y Ecology study of interactions among organisms and their environment that determines

their distribution and abundance (from Krebs 1994)o Biotic interactions among living things

Intraspecies, interspecieso Abiotic interactions between organisms and their nonliving environment

(physical and chemical)

Slide 2y Organismal ecology

o Studies how an organisms structure, physiology, and (for animals) behaviormeet the challenges posed by the environment

y Population ecology


10/54

o Concentrates mainly on factors that affect how many individuals of a particularspecies live in an area

Slide 3y

Community ecologyo Studies how populations of species interact and form functional communitieso Focuses on why some areas are species pooro Also studies succession how species composition and community structure

change over time, particularly after disturbance

Slide 4Temperature tolerance of desert locust = Organismal

What factors influence the diversity of species that make up a particular forest? =

Community

What environmental factors affect the reproductive rate of grizzly bears? = Population

Slide 5y Ecosystem ecology

o Studies energy flow and chemical cycling among the various biotic andabiotic components [within a community & between organisms and theenvironment]

- What factors control photosynthetic productivity in a temperate grassland ecosystem?

Lectures 4-5

Slide 1Species Interactions & Coevolution

Slide 2Co-Evolution

y Long term, evolutionary adjustment of the characteristics of some organisms,sometimes on a reciprocal relationship to one another.

y Coevolution sometimes results in a totally dependent relationship on one another.o E.g., food, shelter/nesting site, pollination service.

Examples: Yucca/moth Host/parasite interactionsFig plant/wasp Shark-remoraOrchids/insects Acacia/Ants


11/54

Slide 3Co-Evolution: Two ecologically interacting species exert reciprocal selection pressures onone another and the response is inherited.y Trait centered

Reciprocal selection pressures occur between interacting species such as:y Host and parasitesy Competitorsy Predators and preyy Mutualistsy Host and symbiont

Slide 4What is co-evolution

Species A evolves an adaptation in response to species B

Species B evolves in response to the adaptation of species A

This cycle keeps revolving between the two

Slide 5Types of species interactionsInteraction between two (or more species) similar/different benefit

Mutualism both benefit

Commensalism one benefits; the other is not harmed

Predation/Parasitism/Herbivory one harmed, one benefits

Competition both harmed

Slide 6Species A versus Species B

Benefit (+) Not Harmed (0) Harmed (-)Benefit (+) Mutualism Commensalism Predation Herbivory

Parasitism

Not Harmed (0) CommensalismHarmed (-) Predation Herbivory

ParasitismCompetition


12/54

Slide 7Types of coevolutionSpecific: one species interacts closely with another. Changes in one species induce adaptivechanges in the other, and vice-versa.

Diffusion: selection imposed reciprocally by one interacting species on another is dependentof the presence or absence of other species.

Slide 8CompetitionDriving force behind evolution and natural selection

Interspecific: Niche differentiation finches, G. Is.Competitive exclusion

Intraspecific: Exploitation competitionInterference competition

Slide 9Competition

y Intraspecific between individuals of the same speciesy Interspecific between individuals of different speciesy Exploitation competition organisms compete indirectly through the consumption of

a limited resource

y Interference competition individuals interact directly with one another by physicalforce or intimidation

Slide 10Competition among barnaclesIn the absence of competition, Chthamalus lives from low to high tide; Semibalanus livesfrom low to mid tide regions. But, together and in competition, Semibalanus overrides andexcludes Chthamalus from their areas of overlap.

Slide 11Wood warblersFive species of wood warbles occur in spruce forests of the northeastern United States.Their foraging efforts are localized in different parts of the tree, represented by theshading.

Slide 12


13/54

SticklebacksTwo different species: Benthic & Limnetic; Morphological character displacement to reducepredation pressure and to improve resource utilization

Slide 13Reciprocal co-evolution: mutualismMutualism: a symbiotic relationship here both species benefit from the interaction

Mutualisms represent one of the most influential of all biological interactions, withfundamental consequences for the evolution and maintenance of biotic diversity

Obligate mutualisms between flowering plants and their insect pollinators constituteextreme cases of interspecific mutualisms.

Slide 14Mutualism fishThe small Spanish hogfish dashes into the mouth of a willing barracuda where it feeds ondebris and parasites. The hogfish gains a meal and the barracuda gains a cleaning.

Slide 15Mutualism birds and crocodilesThis African crocodile relaxes and holds its mouth open. This signalsEgyptian Plovers toenter and safely feed on fouling parasites and debris. The crocodiles gain a cleaning, and theplovers a meal.

Slide 16Mutualism oxpeckerThis red-billed oxpecker forages for parasites on the backs of African ungulates. Here theoxpecker is working around the neck o domestic cattle. Parasites tend to collect along theback of the neck where scratching cannot dislodge them. The oxpecker gains a meal, and itscustomers get ride of parasites.

Slide 17

Mutualism leaf-cutter antsAbove ground, ants cut small pieces of leaves and carry them to their underground nestswhere the chewed leaves enrich soil. Into this soil, bits of fungi are planted that grow andprovide food for the ants.

Slide 18Nectar guides


14/54

Darker petals in the center of the flower made up of UV-absorbing pigments (flavonoids) visible to insects but invisible to other animals.

Slide 19

Mutualism pollination & rewardAmount and quality of nectar & pollenCHO rich nectar

Slide 20Defensive MutualismAcacia/Ant mutualistic association- Ant gets shelter and food, protects the plant from herbivores- Also chew on competing plants

Slide 21Reciprocal co-evolution examples: plant pollinator mutualismsThe fig-wasp mutualism is ancient and diverse, originating ~ 80-90 mya

Ca. 750 species of Ficus

>300 wasp species

One species of wasp thought to pollinate one species of fig

Slide 22Moths: TegeticulayuccasellaYucca plant- Very sticky, so moth is able to carry pollen to other yucca plants

Slide 23Bats- Nocturnal & good olfactation- Strong fliers but not good at flying among branches

Queen of Night

Flowers- Nocturnal- Copious nectar- Heavy scent- Accesible


15/54

Slide 24Legume Rhizobium Symbiosis90-93% species of the Fabaoideae with Rhizobium

Chemical / molecular communication

N2most abundant gas in atmosphereNot available to plants in elemental formConverted to ammonia, nitrates, nitrites

Legume provides the bacteria with CHO (+ other); Rhizobium supplies the host legume withN2 in the form of ammonia (NH4

+). Unlike plants, Rhizobium can fix inert N2from theatmosphere.

- Makes it easier for plants to access

Slide 25Reciprocal co-evolution examples: plants and herbivoresPlant-herbivore Coevolutiony Plants produce toxic secondary chemicals that reduce herbivoryy Some herbivores have evolved to detoxify the toxic chemicals.

o Herbivores may specialize on the hosts whose defenses they have overcomeo Plants may evolve new defenses, and the cycle continues

- This cycle has continued for million of years

Slide 26Reciprocal co-evolution examples: plants and herbivores: Chemical warfareHerbivores often feed on chemically similar plants

o Should impose selective pressures on plants to diverge chemically or biascommunity assembly toward chemical divergence

The effect of herbivory on diversification should be stronger for narrowly coevolvedsystems with fewer interacting species.

ExampleBursera spp. produces an array of terpenes

- Toxic to insect herbivores- Decrease survival and growth of specialized herbivores (bettle: Blepharida)


16/54

Slide 27Plants Chemical WarfareMustard OilDogbane (Cardiac glycosides)Castor Oil (Ricin)

-

Herbivore may avoid some plants (causes heart attacks)- Arms race (evolutionary)

Slide 28Predator prey Coevolution: Arms raceExploitative Ability of Predator

Defense of Prey

Between these is selection, and the cycle between these two does not stop

Slide 29Orange bellied newt (Tarichagranulosa)Tetradotoxiny Na+channel blockery Broad toxicityy Widely distributed taxonomicallyy Can kill 17 adult human or 25 000 mice- After consumption, nervous system will collapse and heart failure will commence

Slide 30Red-sided Garter Snake, Thamnophissirtalis- Resistant to newt toxin

Slide 31GeographicVariation in ResistnaceTrade off: Cost of resistance in snakes: loss of speed

Blue (4-5): selection is low, therefore produces low toxin

Red (>100 MAMU): selection is high, therefore produce high toxin

(Blue is mainly upper part of diagram, red is mainly lower)

Slide 32


17/54


18/54

Slide 38Camouflage inanimate

Slide 39

Camouflage inedibleThe resemblance of these insects to inedible plant parts affords them some protectionfrom predators.

Slide 40Camouflage among/in plants

- Bottom right picture Lithops (Store plants)

Slide 41

Batesian MimicryThe mimic shares signals/characteristics similar to the model

Coral Snake Venomous vs. non-venomous

Monarch vs. Viceroy

Stinging vs. Non-Stinging wasps

- May have certain colour designs to carry characteristics of venomous/dangerousvariation

Slide 42Mullerian MimicryBoth ecologically sympatric pairs are distasteful, and have warning colorations*Sympatric pairs of Heliconius butterflies

- Always adapting and evolving- Convergence of colours

Slide 43

Competition and Biodiversity

Different words, but have many things in common.

All the terms involve animals and plants (species) interacting with each other.

Learn to evolove and depend on each other to complete certain processes.


19/54

The interactive processes make coevolution a potentially powerful evolutionary process inshaping biodiversity.

Species and Co-evolution

Notes for Lectures 6-8

Slide 1Remaining slides from lecture 4-5

Slide 2y Community assemblage of many populations that live in the same place at the same

timey Community ecology studies how groups of species interact and form functional

communities

Slide 3y Two componentsy 1. Species richness

o Total number of speciesy 2. Relative abundance

o Proportion each species represents of the total numbers of organisms

Slide 4Two different communities can have the same species richness, but a different relativeabundance

Both have same species richness (4 species)

Community 1 (A: 25%, B: 25%, C: 25%, D: 25%) = SameDistributionCommunity 2 (A: 80%, B: 5%, C: 5%, D: 10%) =DifferentDistribution

Which is more diverse?- Community- Distribution is important

Slide 5Species with a Large Impact

y Certain species have an especially large impact on the structure of entirecommunities


20/54

o Either because they are highly abundant or because they play a pivotal role(keystone spp.) in community dynamics

Slide 6y

Field studies of sea starso Exhibit their role as a keystone species in intertidal communities

- Not a large number, but plays key role

Slide 7y Observation of sea otter populations and their predation shows the effect the

otters have on ocean communities*Otters would be keystone before introduction of killer whale

Slide 8Ecosystem Engineers (Foundation Species)

y Some organisms exert their influenceo By causing physical changes in the environment that affect community

structure

Slide 9y Some foundation species act as facilitators

o That have positive effects on the survival and reproduction of some of theother species in the community

- Juncus in salt grounds keep salt level low- High abundance regulates/minimizes salt rate and maintain high water level

Slide 10Species Richness

y Number of species in each communityy Number of species of most taxed varies according to geographic range

o Increasing from polar to temperate to maximum in tropical areaso Increases by topographical variationo Reduced by peninsular effect

Slide 11Species richness of birds in North America (Diagram)


21/54

Slide 12Species richness of butterflies in N & S America (Diagram)

Slide 13

Species diversity vs. latitude- Number of vascular plant species per 10000 km2decreases as latitude increases

Slide 14y Four different hypotheses for latitudinal gradient1. Time hypothesis

- Communities diversify, or gain species, with time- Temperate regions have less rich communities than tropical ones because they

are younger and have only more recently recovered from glaciation

- Support more worms in comparable unglaciated lakes than glaciated- Problem limited applicability to marine organisms- Not all about evolutionary time- Hypothesis explains land evolution but not so much water evolution

Slide 152. Area hypothesis

- Larger areas have more species because they can support larger populations anda greater range of habitats

- Support significant relationship between insect diversity and host tree range(species area effect)

- Problem o Tundra: largest biome but low richnesso Open ocean: largest volume, fewer species than tropical surface waters

Slide 16*DiagramInsect species diversity on British host trees

There is a greater number of insect species when there is a larger area of host tree range(km2)

Slide 173. Productivity hypothesis

- Greater production of plants results in greater overall species richness


22/54


23/54

y Eltons diversity stability hypothesiso Disturbances in a species-rich community would be cushioned by large

numbers of interacting species and would not produce as drastic an effect asit would on a less diverse community

y 11-year study examined species richness and stability in grassland plotso

Found year-to-year variation in plant community biomass lower in plots withgreater species richness- Around 200 experimental plots, each a site of various plants- Higher richness, higher nutrition, and therefore higher the chance of survival

Slide 23Plots with different species richnessCoefficient of variation for plant community biomass vs. Average plant species richness

- Total amount of plant biomass/year compared to species richness- Biomass decrease as richness increases

Slide 24Succession

y Gradual and continuous change in species composition and community structure overtime

y Primary succession succession on a newly exposed site that was not previouslyoccupied by soil and vegetation

y Secondary succession succession on a site that has already supported life but thathas undergone a disturbance, such as a fire, tornado, hurricane, or flood

Slide 25Primary Succession*Diagram- Enrichment of nitrogen- Litter falling to forest floor

Slide 26y Succession has a distinct end point (climax community)y Each phase of succession is called a sere or seral stagey Disturbance might set te community back to an earlier seral stagey It then proceeds toward climaxy Each colonizing species make the environment a little differenty Facilitation colonizing species change the environment so that it becomes more

suitable for the next species


24/54

Slide 27A case study of Primary Succession*Diagram

Slide 28A case study of Primary Succession- Soil nitrogen content increase- Contributed by nitrogen fixation bacteria &litterfall- Soil becomes more acidic (competitionaspect)

Slide 29Secondary Succession

- Regeneration may cause composition to change

Slide 30A case study:Eruption of Mt. St. Helens in 1980May 18th, 1980

Slide 31Succession on Mount St. Helens

- Soil not sterilized- This would be secondary succession as it has only taken ~20 years for

regeneration

- Primary would take MUCH longer

Slide 32y Study of succession on islands

Many are volcanic islands Younger in age than closest mainland

Slide 33*DiagramLeft island is


25/54

What will happen in the future ( species richness) when this island forms and cools?- Species will migrate to this new-forming island

Slide 36

-

Study of succession on islandsWhat are some factors that will influence the species richness on this island?e.g.

- Distance from mainland or other islands (source of new species to Is.)immigration rate of species to the island

- Ability to surviveextinction rate of species on the island- Area [Size] of the islandcarrying capacity- Not all that migrate will survive- Immigration and extinction (adaptation)

Slide 37- understanding modern biodiversity

Slide 38Island Biogeography

y Study of succession on islandsy MacArthur and Wilson (1967) developed the equilibrium model of island

biogeography

o Number of species on an island tends toward an equilibrium number thatis determined by the balance between immigration and extinction

Slide 39Important points:New species only competition for resourcesImmigration on Islands

(a) Immigration Curve: as colonists fill the island, the rate of arrival of new speciesdrops

Slide 40Extinction on Islands

(b) Extinction Curve: As colonists fill up the island, the rate at which species disappearincreases. (After MacArthur and Wilson 1967.)

Slide 41


26/54


27/54

Slide 48Island Biogeography equilibrium modelOceanic islandsIslands

Slide 49Basic ideas about Islands: Summary

- Concept of area- Geographic location in relation to mainland- Island populations are at balance- Islands have fewer species than nearby mainland- May have problems with migration- Islands offer tenuous life

Slide 50Some factors that influence the species richness on an island:

- Distance from mainland or other islands (source of new species)- Area [size] of the island- Ability to survive and reproducebiotic factors

Predation, competition, disease, parasitism

Abiotic factors- Physical

o Temperature, light, fire, moisture, soil/rock structure, wind- Chemicalo Water, oxygen, salinity, pH, soil nutrients

Notes forlecture 9-10

Slide 1Influence of Abiotic Factors on SpeciesDistribution & Global Biodiversity Patterns (Biomes)

Slide 2

Interaction between organisms and environment limit the distribution of species*Diagram- Factors influence organisms on a global scale

Slide 3Abiotic factors that influence species distributionTerrestrialEnvironment


28/54

y Sunlighty Temperaturey Precipitationy Windy Latitudey

Altitudey Soil

AquaticEnvironmenty Light penetrationy Water temperaturey Dissolved nutrient concentrations (especially N and P)y Water currentsy Salinity

Slide 4y Temperature

o Most important factor in the distribution or organismso Effects on biological processeso Inability of most organisms to regulate body temperature precisely

Ectothermic vs. Endothermic

- Endo uses own energy to maintain body temp.- Ecto allow temp to change

Slide 5y Frost is the most important factor limiting geographic distribution of tropical and

subtropical plantsy Cactus distribution limited to place where the temperature does not remain below

freezing for more than one night

Slide 6y Endothermic animal ranges also affectedy Vampire bats limited to area where average minimum temperature in January is

above 10 degrees Celsius

- Animals that are smaller in size tend to lose more energy (heat) faster- Energetically very expensive, must maintain

Slide 7


29/54

y Coral reef organisms abundant only in warm water due to effects of temperature oncoral deposition

y Coral zooxanthelae symbiosis is threatened by rising ocean temperatureo When temperature increases over 20 degrees Celsius, photosynthesis stops,

therefore dangerously high levels of CO2y

If Temp is too low, coral will not grow (calicification)

Slide 8Influence of Light Penetration

y In aquatic environments, water absorbs light preventing photosynthesis at depthsgreater than 100 m (euphotic zone)

y Red algae occur at greater depths because they possess pigments enabling them touse blue-green light

Pigment: Phycoerythrin

Slide 9Influence of Salts in the water

y Freshwater fish tend to gain water and have to constantly eliminate watery Marine fish lose water and must drink water to compensate

Euryhaline fish: has developed tolerance to a wide range of salt levels in water- must adapt to different kinds of water

Slide 10

What is a Biome?A large geographical area with characteristic plants and animalsTerrestrial Biome Types*Diagram

- Biomes distributed across the world- Each has own unique characteristic plan (pattern)

Slide 11Relationship between terrestrial biome types and temperature and precipitation*Diagram

Slide 12Climate and Biological Communities

y Climate prevailing weather pattern in a regiono Temperature, water, wind, and light are components

y Climate predicts the occurrence of specific biomes major community types


30/54

Slide 13Why do climates vary geographically?Solar energy input varies with latitude

Slide 14Global temperature differences create winds and drive atmospheric circulation

y Hadley proposed one large convection in each hemispherey High Temp. at equator causing air to rise and flow north and south toward polesy Air would cool and fall, flowing back to the equator

Slide 15Coriolis effect: effect ofEarths rotationThree cell model: Hadley, Ferrell & Polar

*Diagram

Slide 16Local and seasonal effects on climate

y Oceans and topographic features such as mountain ranges can affect local climatesy Ocean currents can influence climate in coastal areas.

Slide 17Tropical forest: Thick canopy blocking light to bottom strata, many trees covered by

epiphytesSpecies richness: extremely high (animals & plants)

- Epiphytes are plants that grow on other plants

Slide 18Taiga (Boreal Forest): one of the largest terrestrial biome receives lots of moisture as rainor snow.Species richness: plants (low), animals (low, but varies seasonally)

Slide 19Temperate Grassland: Marked by seasonal drought and fires, and grazing by large animals.Species richness: plants (fairly high), animals (relatively low)

Slide 20


31/54

Tundra: Permafrost (Permanent frozen ground), bitter cold, high winds and thus no trees.Has 20% of land surface on earth. Low species richness (animals & plants)

Slide 21

Desert: Plants and animals adapted for water storage and conservation. Can be either veryhot, or very cold (e.g. Antarctica). Moderate to very low species richness.

Slide 22Aquatic biomes cover about 75% of theEarths surface

- Wetlands- Lakes- Rivers, streams- Intertidal zones- Oceanic pelagic biome- Coral reefs- Abyssal zones (includes hydrothermal vents)

Slide 23Geographical distribution of major aquatic biomes*Diagram

Slide 24Lake stratification and mixingalters oxygen and nutrient levels. Dependent on

temperature changes and effect on water density.- Lake stratifies based on temp. and oxygen- When thermocline occurs, mixing stops- Mixing occurs, lake water enriched in nutrients

Slide 25Oligotrophic Lake: Nutrient poor, water is clear, oxygen rich; little productivity by algae,often have high diversity of fish.

Slide 26Entrophic Lake: nutrient rich, lots of algal productivity so its oxygen poor at times, highalgal diversity, but low diversity of fish

Slide 27Rivers and Streams: Organisms need adaptations so that they are not swept away by movingwater; heavily affected by human activities


32/54

Slide 28Wetlands: includes marshes, bogs, swamps, seasonal ponds. Among riches biomes withrespect to biodiversity and productivity. Very few now exist.

Slide 29Estuary: Place where freshwater stream or river merges with the ocean. Highly productivebiome; rich in euryhaline species.

Slide 30Marine environment with zonation*Diagram

Slide 31Influence of zonation on marine community structure

- Each has own structure to live at certain depths

Slide 32Community structures in aquatic biomes are primarily distinguished by differences of:

- Light availability- Oxygen gradient- Current strength- Temperature gradient

Additional Notes for Lecture 10

Slide 1Ecosystems and ecosystem diversity

- What is an ecosystem?- Key terms

y Autotroph & heterotrophy Carnivore, decomposer / detritus feeder, herbivore & omnivorey Producer & consumer (primary, secondary, tertiary)y Food chain & food weby Trophic level

Slide 2Hierarchy of life (= levels of biological organization)

1. Atoms2. Molecules & Macromolecules


33/54

3. Cells4. Tissues5. Organ &6. Organ Systems7. Organism8.

Species (form)9. Populations

10. Community11. Ecosystem12. Biosphere

Slide 3What is an ecosystem?

- Term defined in 135 by British plant ecologist Sir Arthur George Tanlsey- Includes the biotic communities of organisms in a defined area and the abiotic

environment affecting that community

y Ecosystems vary in size (example)o Microscale to macroscale

- Potholeso Has own plant/animal distribution

Slide 4Pond

**Some organisms can move in and out of a well defined ecosystem

Oasis(With plants, frog, fish, birds, insects, etc.)

Slide 5PrairieEcosystemKelp ForestEcosystem

Slide 6Ecosystem ecology = study of the movement of energy and materials trough organisms andtheir communities

Energy moves in one direction (from producers to consumers)From autotrophs to heterotrophsTrophic level = each feeding levelGK: trophos = feeder


34/54

Concept: food chains & food webs(Simple/linear versus complex interconnected chains)

Ex. Photosynthetic plants to herbivores

Autotrophs

Heterotrophs

Slide 7Food chains*Diagram of Trophic level, Terrestrial food chain and Aquatic food chain

- Primary producer is autotroph (Plant or phytoplankton)- Everything after the base (primary producer) is a heterotroph- Primary consumer (herbivore) [Caterpillar and zooplankton)- Secondary consumer (carnivore) [Lizard and Fish]- Tertiary consumer (secondary carnivore) [Snake or Pelican]

y Plants, many protists (algae) and photosynthetic prokaryotes are at the basey Base organisms produce energy-rich tissue

Slide 8Energy passes from one trophic level to another*Diagram

y Much energy from 1sttrophic level goes unconsumed by herbivoresy Energy lost as heat in a single trophic levely Energy lost in the conversion from one trophic level to another- Unconsumed plants die and decompose in place- This material along with dead remains of animals and waste productsDetritus

(=debris)

Slide 9- Decomposer breakdown dead organisms rom any trophic level- Organisms that get energy from detritus = detrivores /decomposers [=saprotrophs]- Detrivores / decomposers probably carry out 80-90% of the consumption of plant

matter

Slide 10Relationships between organisms in an ecosystem are more complexFood Web (prairie ecosystem)

Trophic levels for the different organisms1. Primary producers


35/54

2. Primary consumers3. Secondary consumers4. Detrivore /Decomposer

Slide 11Food web (African SavannaEcosystem)

Notes forlecture 11

Slide 1Remaining slides from the additional notes of lecture 10

Slide 2Some organisms can occupy more than on trophic level

Venus Flytrap (Dionaeamuscipula)- Primary producer- Secondary consumer- Once it traps insects, it will remain closed for 5 10 days and release digestive

enzymes- Found in areas low in nitrogen- Compensate for deficiency

Slide 3

y Chain lengths are short in most food webso Chain length refers to the number of links between the trophic levels

involvedo Usually less than 6 levelso Based on laws of physics and chemistry

y Second law of thermodynamics energy conversions are not 100% efficient and that,in any transfer process, some energy is lost

Slide 4Energy transfer and loss in a forest

Slide 5An energy pyramid for a prairie ecosystem

Slide 6


36/54

y Can compare the efficiency of energy transfer through trophic levels in differenttypes of food webs

y Two measures of the efficiency of consumers as energy transformerso Production efficiencyo Trophic-level transfer efficiency

Slide 7Production efficiency = Net productivity / Assimilation x 100

y Production efficiencyo Percentage of energy assimilated by an organism that becomes incorporated

into new biomasso Invertebrates average 10-40%o Vertebrates have lower production efficiencies

Fish (ectotherms) around 10% Birds and mammls (endotherms) 1-2%

y Why?o Have to maintain body temperatureo Use own energy

Slide 8Trophic-level transfer = Production at trophic level n / Production at trophic level n 1 x100

y Trophic-level transfer efficiencyo Amount of energy at one trophic level that is acquired by the trophic level

above and incorporated into biomasso Examines energy flow between trophic levels, not just individual species

Slide 9Trophic-level transfer efficiency

y Averages around 10% with much variationo Some marine food chains exceed 30%

y Low for two reasonso Many organisms cannot digest all of their preyo Much assimilated energy lost as heat

y Limits number of trophic levels in a food web

Slide 10Ecological pyramids in food webs: numbers*Diagram

Slide 11y Pyramid of numbers


37/54

o Number of individuals decreases at each trophic levelo Inverted pyramids single producer supports hundreds of herbivores and

thousands of predators Oak tree supports beetles, caterpillars, and their predators

y Use pyramid of biomass

Can still occur even in pyramid of biomassy Small phytoplankton standing crop supports higher biomass

of zooplankton by processing large amounts of energyy Use pyramid of production

Slide 12Ecological pyramids in food webs: Biomass*Diagram

Slide 13Energy flow and Biomass distribution*Diagram

Slide 14Net Primary Productivity (NPP) varies among regions

- NPP = GPP (Gross Primary Productivity) - Respiration

Slide 15

Net Primary productivity (NPP) varies among biomes

Slide 16Human Impacts: Food web & Toxins in theEnvironment

y Humans release an immense variety of toxic chemicalso Including thousands of synthetics previously unknown to nature

y One of the reasons such toxins are so harmfulo Is that they become more concentrated in successive trophic levels of a

food web

Slide 17y In biomagnification toxins concentrate at higher trophic levels (e.g. DDT, PCB)- DDT was used for managing pest, used for a diverse amount of reasons- Over time concentration becomes large and may permeate and remain in environment

and organisms- Organisms cannot break it down, metabolize


38/54

Slide 18Peregrine FalconDiagram

- High levels ofDDT-

Birds with large amounts ofDDT would lay eggs with very thin shells, affected thepopulation

Slide 19Silent Spring Rachel Carson

Slide 20y Biomagnification

o Tendency of certain chemicals to accumulate or build up within food chains(e.g. DDT, PCB, Methyl-HG)

o Persistent in the environmento Low solubility in water/high solubility in fats or lipids (tends to concentrate

in tissue)o Higher trophic levels amass large concentrationso Interferes with eggshell formation resulting in thin shelled eggs that breako Resulted to population decline of many fish-eating birds

Notes forlecture #12-13

Slide 1

Biogeochemical cyclesy Nutrients (C, N, P & S) cycles involve

o Biological transport absorption of chemicals by living organisms and theirsubsequent release back into the environment

o Geological transport weathering and erosion of rocks, and elementstransported by surface and subsurface drainage

o Chemical transport dissolved matter in rain and snow, wind driventransport of atmospheric gases

y The human population is disrupting nutrient/chemical throughout the biosphere

Slide 2*Diagram

Slide 3Carbon cycle

- Present in atmosphere in low concentrations- Autotrophs incorporate it into organic matter via photosynthesis


39/54

- Respiration and decomposition of plants recycles a similar amount back into theatmosphere as CO2

- Carbon is incorporated into shells of marine organisms eventually forming limestonedeposits

Slide 4- Volcanoes and hot springs release large amounts- Burning fossil fuels is adding CO2and particulate matter to the atmosphere- CO2 is the most significant of the greenhouse gases, which are a primary source of

global warming

What are the other major natural greenhouse gases?Nitrous oxide, methane, water vapour

Slide 5Where is all the CO2(C) going to go?*Diagram

Slide 6The GreenhouseEffect*Diagram- Minimal heat radiated fromEarth escapes into space- Majority of heat radiated fromEarth is redirected back toEarth

Slide 7Primary Contributors to the Natural GreenhouseEffectCarbonDioxide ~25%Other ~10%WaterVapour ~65%

Slide 8Other planets also have GreenhouseEffects, but these are unsuitable for life

Planet GH Gases Surface Temperature GHE

ffectVenus >90% CO2 450 degrees Celsius 550 degrees Celsius

Earth ~0.04% CO2, ~1% H2O 15 degrees Celsius 33 degrees Celsius

- Venus is far too hot, Earth is not bad


40/54

Slide 9Rising Atmospheric CO2

y Due to the increased burning of fossil fuels and other human activitieso Concentration of atmospheric CO2has been steadily increasing

Slide 10Increased levels of atmospheric CO2are magnifying the greenhouse effect and magnifyingglobal climatic change

- General increase in temperature over ~100 years

Slide 11Global Warming Potential of various natural Greenhouse Gases

Gas Residence Time (yr) Global Warming Potential (molarbasis)

CO2 230 1

CH4 14.4 10

N2O 160 180

- CH4and N2O are more capable of trapping heat- CO2remains in atmosphere much longer

Slide 12Estimated and Predicted Global Concentration of Atmospheric Greenhouse Gases

Gas Pre-industrial Current 2050 scenario

CO2 275 ppm 345 ppm 500-600 ppmCH4 0.7 ppm 1.7 ppm 2.1-4 ppm

N2O 285 ppb 304 ppb 350-400 ppb

Slide 13Sea Ice Thickness (10-year average)

Slide 14Global warming

- Human activities increasing the greenhouse effect- All greenhouse gases have increased in atmospheric concentrations since industrial

times- Anticipated changes in global climate will occur too rapidly for normal evolutionary

processes to compensate- Can result in massive loss of biodiversity on a global scale


41/54

Slide 15Most rapid changes are occurring in the polar ecosystems

- Temperature has increased by about 25 degrees Celsius in last 50 years- Loss of sea ice has decreased productivity, habitat- It has subsequently affected polar food web-

Krill (Keystone species) population has plummeted- Krill main food source for whales, seals, penguins

Slide 16Nitrogen Cycle*DiagramWhy elemental nitrogen is inaccessible to most organisms?

- Its an inert gas (triple bond), very hard to break down

Slide 17Nitrogen Cycle

- It is essential component of proteins, nucleic acids and chlorophyll- 78% ofEarths atmosphere is N2but largely inaccessible1. Nitrogen fixation only certain bacteria are able to convert N2and release ammonia

(NH3) or ammonium (NH4+)

2. Nitrification soil bacteria convert NH3or NH4+ into nitrate (NO3-) used by plants

Slide 18

3. Assimilation plants and animals incorporate ammonia and NO3-

4. Ammonification conversion of organic nitrogen to NH3and NH4+by bacteria and

fungi (most common pathway for nitrogen to enter soil)5. Denitrification reduction of nitrate (NO3-) to gaseous nitrogen (N2) by bacteria

returns a small amount of nitrogen to the atmosphere

Slide 19y Human alterations of the nitrogen cycle have approximately doubled the rate of

nitrogen input to the cycley Fertilizer runoff can cause eutrophication (nutrient enrichment of soil/water)y Burning fossil fuels also releases nitrogen oxides which can react with rain to formacid rain (nitric acid)- Speeding up eutrophication process

Slide 20Phosphorous Cycle


42/54

*Diagram

Slide 21y Phosphorus is limiting element in most aquatic systemsy

Human input: fertilizer & sewagey More phosphorus increases aquatic productivityy Eutrophication elevated nutrient levels in the watery CulturalEutrophication nutrient enrichment due to human input, leads to

unregulated algal growth

Slide 22Are all nutrients equal in the ecosystems?

y Some nutrients limit primary productivityy Sometimes more than one nutrient may limit productivityy Bacterial, algal and plant growth are stimulated by the addition of a limiting nutrient

Slide 23*Diagram

Slide 24y Classic WholeEcosystem Case Study (1969: fertilization of Lake 226 (ELA, Kenora,

ON)y Objective: Which (C, N & P) are limiting primary production?y Led to the banning of P in detergents and reduction of P inputs from sewagetreatment plants in Canada, U.S. &Europe

Slide 25Human Impacts: AnExample of a Growing Problem

y Excess P applied to agricultural landscapes is carried into surface waters where italso causes excess algal and plant growth in lakes, rivers, estuaries and coastalsystems (eutrophication).

y PO4binds quickly to soil particles and tends to accumulatey Agricultural landscapes are becoming saturated with P.y As these soils erode, they carry P into water bodies

Slide 26LakeEcosystems

y In temperate climate lakes, phosphorus is a strong limiting nutrient


43/54

Slide 27y Temperate Lakes

o Are sensitive to seasonal temperature changeo Experience seasonal turnovero Cultural eutrophication is common in nutrient rich temperate lakes

Slide 28Impact of CulturalEutrophication on AquaticEcosystems

y Unregulated algal growth (algal bloom)

Slide 29Other Impacts:Various Types of Algae Can FlourishDue to NutrientEnrichment

y Chlorophytes (Green Algae)y Cyanobacteria (Blue-green Algae)y Diatomsy Dinoflagellates

Slide 30(Dominated byDinoflagellates)Red Tides

y Common to tropical and subtropical coast lines and estuariesy About 40 species create serious toxinsy But can also be found in temperate coastal waters in late spring and summer

Red tide off the east coast of Italy

Toxins may be produced to deter herbivores (zooplankton)

Slide 31Food WebEffects of SomeDinoflagellate Toxins AreDrastic

y Humpback Whale (Dead)y Loons on Coast of N. Carolina (Dead)y Lesions on Fish (Dead)y Beach covered with dead fish

Slide 32Back to Red Tides: Increased Occurrence of PSP Worldwide from 1970 to 2000

- Affects humans because of consumption of contaminated marine animals- Accumulate huge amount of toxins


44/54

Slide 33y Algal bloom, eventually leads to hypoxic/anoxic water

o Because every stem has a carrying capacity (Exceed)y Over time, could alter community structure dominated by tolerant speciesy Release of toxins, massive fish kill, loss of biodiversityy

Contamination of toxins in human drinking water source & food (e.g., paralyticshellfish poisoning)

Slide 34Sulfur CyclePyriteIron sulfite

- Sulfur mineral abundant in crust- Released through atmosphere (cycled) as acid rain- Sulfur is highly soluble

Human Implicationsy Burning fossil fuelsy Mining, smelting

Slide 35Sulphur Cycle

- Most naturally produced sulphur in the atmosphere comes fromo Hydrogen sulfide gas (H2S) released from volcanic eruptionso Decomposition, especially in wetland environments, where sulphur is very

common

Slide 36- H2S quickly oxidizes into sulphur dioxide (SO2)- SO2 is soluble in water and returns toEarth as weak sulfuric acid (H2SO4), or

natural acid rain (pH 5.6)- Sulphate ions, SO4- enter soil- Sulphate-reducing bacteria in soil may release sulphur as H2S, or the Sulphate may

be incorporated by plants into their tissue

Slide 37- Certain marine algae and a few salt marsh plants produce relatively large amounts of

the sulfurous gas dimethyl sulfide (CH3SCH3)o Small particles form nuclei that water condenses around forming clouds

Slide 38- Fossil fuel burning has altered the sulfur cycle the most


45/54

o Large amounts of sulfur dioxide (SO2)o Reacts with rain to produce anthropogenic acid rain with a pH of 4.1-4.5

Slide 39

Acid Rain Impacted Regions ofEaster & Central Canada- Highly impacted areas of acid rain- Lot of industry (suburbs, cities) mining/smelting region

Slide 40Impact of Acid Rain on TerrestrialEcosystems

y Soil infertility (leaching of nutrients, decrease in microbial activity)y Deforestation and habitat loss

Slide 41Impact of Acid Rain on AquaticEcosystems*Diagram- The top of the food chain has a more drastic change- Ecosystems affected by acid rain is much simpler, not as complex/diverse (right side of

diagram)

(Slide 42)SummaryCarbon cycle green house effect, effects on global biodiversity

Nitrogen cycle limiting nutrient, eutrophication, acid rain, loss of biodiversityPhosphorus cycle limiting nutrient, local cycle, eutrophication, algal bloom, loss of aquaticbiodiversitySulfur cycle acid rain, loss of aquatic biodiversity

Notes forlecture 14

Slide 1Remaining portion of the notes for lecture #12-13

Slide 2Anthropogenic Causes of biodiversity loss

y Deforestation & Habitat destructiony Over-exploitation/inbreeding/genetic drifty Introduced speciesy Impacts on nutrient/chemical cyclingy Global warming/climate changey Pollution


46/54

Slide 3AnimalExtinctions and Human Population GrowthBiodiversity crisis in the past 100 years, 20 species of mammals and over 40 species of

birds have gone extinct

Growth of human populations is linked to number of extinctions

Slide 4International Union for Conservation of Nature (IUCN)

- Founded in 1948, Headquarter: Switzerland, involves 11 000 scientists & volunteersfrom 160 countries

- The main global biodiversity monitoring organization- Dedicated to natural resource conservation- Publishes Red List: rate which species are most endangered

Slide 52007 IUCN Red List*DiagramThe percentage of species in several groups which are listed as critically endangered (red),endangered (orange), or vulnerable (yellow).

Slide 6

Biodiversity hotspots areas with a high concentration of endemic species, experiencingrapid loss of species[Extinction Hotspots]Hotspots contain greater than or equal to 1 500 species of endemic vascular plants

- Lost about 70% of the original habitat

Slide 7Amphibians: another threatened group, very sensitiveThe Monteverde, Costa Rica caseExtinction of the Golden Tad (Bufoperiglenes)

Vanished in a span of less than 5 yearsComplete disappearance in 1987Reasons: Pollution (Pesticide use), Global warming (fungal disease)?

Slide 8Effects of different factors*Diagram


47/54

Slide 9Deforestation and Habitat LossCaused by demand for wood products, need for space, farmland, housing, roads

Deforestation causes habitat fragmentationAnimals and plants are forced into confined areasResults into populations that are too small to survive

Little Islands (patches of forest)

Question: Which type of species are likely to disappear from small forest fragments?- Large organisms (top of the food chain)

Slide 10DirectExplanation

A Case Study the Passenger Pigeon (Ectopistesmigratorius)Extiction caused by humans

Once probably the most numerous bird on the planetHabitat: Primary forest of N. America (Eof the Rockies)Flocks: a mile wide and 300 mile long

Pop. 19thCentury: 1 to 4 billion (40% of N. Americas birds)

- Over-hunting/marketing- Habitat destruction Loss of nesting areas

Slide 11The last Passenger Pigeon, named Martha, died alone at the CincinnatiZoo at about 1:00 p.m.on September 1, 1914.

- Once most numerous bird onEarth is forever gone!

Notes for Lecture #15

Slide 1Remaining portion of the lecture #14

Slide 2Introduced species

y Humans are constantly moving species between continents, islandso Deliberate or accidentalo Some become invasiveo Islands or confined ecosystems are at risk


48/54

Slide 3Island of Guam

y Brown tree snake (Boigairregularis) introduced accidentallyy Decimated native bird population which evolved in the absence of predators and

lacked the ability to fly (caused at least 12 extinctions)y Threat to many native small lizards and mammals

Slide 4Argentinian Ant (Linepithemahumile)

y Was accidentally introduced into the USAy Have decimated native ants species in Californiay Exhibit low intraspecific competition, form large colonies, ecologically very dominant

species

Slide 5Sierra Nevada (California):

y Introduced non-native trouts for sport fishing, which prey on Ranamuscosay Several studies have implicated introduced trout as one of the main sources of their

decline

Slide 6*Invasive SpeciesDiagram

Slide 7y Zebra mussels: Native to the Caspian Sea region of Asiay Transported to the Great Lakes via ballast water from a transoceanic vessely First discovered in Lake St. Clair, nearDetroit in 1988y Since then, they have spread rapidly to all of the Great Lakes and connected

waterways in many US states, as well as Ontario and Quebecy Extreme biofouling activity, nuisance to humansy Outcompeted native mussels species

BiofoulingIncreased growth of unwanted population

Slide 8Rapid spread ofZebra Mussel*Diagram

Slide 9Terminator carp threatens Great Lakes


49/54

Environmentalists say Asian carp, an invasive species of food-guzzling fish, could cause anecological disaster if it enters Lake Michigan

y First introduced to southern states of the US from China in the 1970s to help cleantanks in fish farms

y They escaped and over the last 30 years have steadily worked their way up theMississippi River system to the Great Lakes

y Voracious eaters, grow very big, having devastating effects on native fishpopulations

Slide 10Why are invasive species often so successful?

- Very good competitors (out-compete the native species)- Pioneer species, few native predators- Prey organisms lack anti-predator defenses- No parasite

Slide 11Inbreeding: Loss of genetic diversity

y Mating among relativesy More likely when population is smally Survivorship of offspring can decline

Slide 12Case study:

Greater prairie chicken Reduced to population with 5 or 6 males, resulted in steadyreduction of hatching success, brought in Kansas birds to increase diversity

Slide 13GeneticDrift: has strong effects in small populations; changes allele frequency, reducesgenetic variation

BottleneckEffect: genetic drift resulting from an event that drastically reduces populationsize, e.g., natural disasters (earthquakes and floods), disease, over-hunting and starvation

Analogy: shaking marbles out of a neck of bottle

Slide 14BottleneckEffectExample: The northern elephant seal


50/54

By 1890 hunting had reduced the northern elephant seal population to 20 animals (a singlepopulation) in Mexico

After becoming a protected species the population rebounded to 30 000 individuals

However, of 24 gene loci examined, no variation was found

That is, only one allele was found for each gene

Other related seal populations abound in genetic variation

- More variation = better survival- Less variation = more vulnerable

Slide 15

Reducing the loss of genetic diversity is key to the survivaly Grizzly bears need large population sizesy Effective population size is 25% (not all bears breed)y Even fairly large, isolated populations are vulnerable to the harmful effects of loss

of genetic variation

What process can enhance the genetic diversity in such isolated populations?- Take bears in other populations and move them to different population

Slide 16

ExtinctionVortex downward spiral of population decline from which it can not naturallyrecover, can be caused by inbreeding & genetic drift*DiagramNote: All species have a minimal population size (MinimumViable Population)

Notes for Lecture #16

Slide 1Remaining portion of lecture # 15

Slide 2BiologicalDiversity (biodiversity)What is it? The totality of genes, species, and ecosystems ina region/world

y The variety of the worlds organisms = genetic diversity and the assemblages theyform

y Blanket term for the natural biological wealth that under-girds human life and well-being = million years evolution


51/54

Human cultures have emerged & adapted to the local environment, discovering, using, andaltering biotic resources.

Slide 3

Current Biodiversityy Identified modern species as of 2009 > 1.9 My Numbers in different groups are related to human interest, not to necessarily to

biological importancey Organisms that cant be isolated and grown in pure culture under ambient condition

are particularly difficult to study.y A scientific description ( = formal identification) is a substantial effort

comparative morphology, biochemistry, physiology, DNA sequence (multiple genes),distribution, behavior, with related taxa.

Slide 4Biodiversity divided into hierarchical categories: genes, species, ecosystems & culture.They describe different aspects of living systems that are measured in different ways.

1. GeneticDiversity:Variation of genes within speciesy It can be between distinct populations of the same species or genetic variation

within a population.2. SpeciesDiversity:Variety of species within a region

y Measured in many ways, e.g., the number of species in a region (speciesrichness) is often used. Taxanomic diversity = the relationship of species toeach other.

3. EcosystemDiversity: It is harder to measure than species or genetic diversitybecause the boundaries of communities and ecosystems are elusive.

Slide 5*Diagram

Slide 6CulturalDiversityLike genetic or species diversity, some attributes of human cultures represent solutions tothe problems of survival in particular environments. Cultural diversity helps people adapt to

changing conditions. It is manifested in language, religious beliefs, land managementpractices, art, music, social structure, crop selection, diet, and other social attributes.

Slide 7Why should we Conserve Biodiversity?Humans depend on plants, animals, and microorganisms for a wide range of food, medicine,and industrial products.


52/54


53/54

y Eliminating waste and toxinsy Pollination

Pollinators: Insects pollinate 2/3 of crop species ~ 25% of foods consumed

Slide 13Bee decline already having dramatic effect on pollination of plants

A decline in bees and global warming are having a damaging effect on the pollination ofplants, new research claims

- Decline of honey-bee colonies in US- A major threat to global food security!

Slide 14What is conservation biology?An applied science, devoted to protect & manage earths biodiversity. It is guided by threebasic principles:

1. Evolution is the process that unites all of biology2. The ecological world is dynamic3. Humans are a part of ecosystems

Slide 15Conservation Strategies

y Habitat conservation focuses ono Megadiversity countries greatest number of species

Just 17 countries are home to nearly 70% of all known species Brazil, Indonesia and Columbia top the list

Slide 16Location of major biodiversity hot spots around the world

Slide 17

Hotspots (Areas rich in endemic species)- Endemics are found only in a particular place an nowhere else- 34 hot spots occupy only 2.3% ofEarths surface but contain 150 000 endemic plant

species (50% of world total)- Receive more attention at the expense of other areas- Put species in hot spots under protection- This strategy has its flaws!


54/54

Slide 18Representative habitats

- Many areas that are threatened but not biologically rich should be preserved as well

Example: Grassland biomes

- Natural habitat for many unique plant & animal species

professor niyogi bio notes

Documents