Evolution and Diversity Evolution and Diversity of Lifeof Life

Module 4 Topics:Module 4 Topics:

Chapter 14: Origin of Life

Chapter 15: Evidence and Theory

Chapter 16: Populations & Species

Chapter 17: Human Evolution

Chapter 18: Classification

Chapter 14: Origins of Life

• Biogenesis: “All living things (currently) come from other living things”– This seems reasonable, but has not always been

accepted. At one time, spontaneous generation myths were widespread.

• Spontaneous generation: The largely discredited belief that living things could easily arise from non living things.– These are now mostly considered myths, but it can be

argued that spontaneous generation must have taken place at least once

Spontaneous Generation Myths

• Can maggots be created from rotten meat?• Can rice grains turn into mice?• Can mud turn into fish?• Can broth turn into germs?

–At one time people believed all of the above ideas. Today we know that these are just myths.

–No careful observer has ever observed rice turning into mice. We now know maggots are actually baby flies, whose eggs were laid in the rotten meat.

Spontaneous Generation was Disproved by Experimentation

• Francisco REDI’s Experiment– Proved maggots come from fly eggs. P.261

• Lazzaro SPALLANZANI’s Experiment– Showed micro-organisms do not grow in

sealed jars (but excluded oxygen) P. 262

• Louis PASTEUR’s Experiment– Proved micro-organisms are carried in dirty

air, not spontaneously generated (his experiment allowed clean air in) P. 263

Abiogenesis:Spontaneous Generation Once Long Ago

• So how did life get here if spontaneous generation does not take place?

• It must have happened once-upon-a-time!• Remember: The world 4 billion years ago

was very different from what it is now.– Atmosphere then: Hydrogen (H2), Methane

(CH4), Ammonia(NH3), Carbon dioxide(CO2), Water vapour

– Atmosphere now: Nitrogen (≈78%), Oxygen (≈21%), Carbon dioxide (<1%), Water vapour (variable), Argon (trace)

Age of the Earth:

• Big Bang: ≈13.7 billion years ago• Sun formed =5 or 6 billion years ago• Earth formed: ≈ 4.5 billion years ago• Earth cooled: ≈ 4.0 billion years ago• First Life formed: c. 3.2 to 3.8 billion years ago• Multicellular life: ≈ 500 million years ago• Reptiles ≈ 250 million years ago• End of dinosaurs ≈ 65 million years ago• Hominids > 3 million years ago

Geological Clock

Ancient Earth

• The world 4 billion years ago was very different from what it is now.– The atmosphere had more Hydrogen (H2),

Methane (CH4), Ammonia(NH3), and Carbon dioxide(CO2) than it does now

– The earth was warmer, with seas just below boiling

– The weather more violent, with powerful thunderstorms

Oparin’s Hypothesis• In 1923 Alexander Oparin

suggested that the conditions on early earth could give rise to organic compounds spontaneously.

• To demonstrate Oparin’s hypothesis in 1953 two graduate students (Harold Urey & Stanley Miller ) built an apparatus containing the gases he believed were present in the early atmosphere

Alexander Oparin

Harold C. Stanley Urey Miller

Miller & Urey’s Device• They filled the bottom of their

device with water, and heated it to simulate warm ancient oceans

• They used a spark chamber to simulate lightning

• After running this device for several weeks they discovered that they had produced several organic compounds, including amino acids

Enlarged diagram of Urey-Miller apparatus

“Primordial Soup”

• The main hypothesis coming from Miller and Urey’s experiment and Oparin’s original hypothesis is that the early Earth’s oceans filled with organic compounds, becoming a sort of primordial ooze, slime or soup.

• Within this more concentrated organic soup, it was possible for the right arrangement of chemicals to come together to form a primitive form of life.

Alternate Theories

• Some Biologists have suggested other mechanisms for making complex compounds, and variations on Oparin’s “Primordial Soup” hypothesis, including:

• The organic compounds may have become even more concentrated in shallow pools along the ocean shore

• Organic compounds could have come together in pores in rocky or sandy surfaces.

• Life may have started in deep ocean hydrothermal vents.• Some organic compounds may have formed in space or on

other planets, and been brought to Earth on meteorites. “There are those who believe life here began out there, far across the universe.”

(I recall an old SF show that started with those exact words.)

Chapter 15: Theory and EvidenceChapter 15: Theory and Evidence

• In this chapter we will examine the evidence that life has changed over time.

• We will look at several theories about how those changes have occurred.

Fossils

A fossil is a trace of a long-dead organism

There are many types of fossils• Mold fossils are imprints, like

footprints, and impressions of skin, feathers or bark

• Cast fossils are made when the remains of ancient things are filled with minerals, like fossilized bones or petrified wood.

• Fossils can also be preserved in amber (fossilized plant resin) or tar (a thick form of crude oil)

Who discovered fossils?

• Fossils have been dug up for centuries. In ancient China some fossils were called “dragon bones”

• The first European to realize that fossils were the remains of extinct animals was Robert Hooke (the same guy who first observed dead cells)

Layers of Fossils

• In general, fossils exist buried in sedimentary rock layers laid down on the bottom of lakes, rivers and oceans long ago.

• In general, the deeper the layer (or stratum) from which the fossil comes, the older the fossil is.

• Some fossils can be dated by radioactive materials in them.

Older fossils

Younger fossils

The Eons of TimeMillions of Years Ago

PhanerozoicEon (multicellular)

Cenozoic era Quaternary, Tertiaray Mammals

200 Mesozoic era Cretaceous, Jurassic, Triassic Reptiles, birds

400 Paleozoic Permian, Carboniferous, Devonian Fish

600 Silurian, Ordovician, Cambrian Invertebrates

800

ProterozoicEon (eukaryotes)

Neoproterozic The periods that go before this point are often lumped together

and called the Precambrian

Each era of the Precambrian can be divided into several periods, but they are not listed here because its hard to fit them all in.

1000 (1 billion) Mesoproterozic

1200 Paleoproterozoic

1400

1600 Eukaryotes?

1800

Archean Eon(prokaryotes)

Neoarchean?

2000 (2 billion)

2200 Meoarchean?

2400 Bacteria?

2600

Hadean Eon(no life)

Paleoarchean?

2800

3000 (3 billion)

3200 Eoarchean Heavy bombardment ends

3400 Earth cools, Oceans form

3600 Heavy comet bombardment!

3800

4000 (4 billion) Sun & Planets form

Eons Eras Periods (what was going on)

The starting point for the Archean Eon has been set at varios points in this rangeMost now put it at about 3.8 billion years ago

Geological Calendar of the Phanerozoic Eon

Years ago Era Period (traditional) Period (official) Epoch

now Cenozoic Quaternary Neogene Recent, Pleistocene

Pliocene,

Miocene2 million Tertiary

35 million Paleogene Oligocene, Eocene

Paleocene

65 million Mesozoic Cretaceous (K) Cretaceous Late Cretaceous , Early Cretaceous

Late, Middle, and Early Jurassic

Late, Middle, and Early Triassic

144 million Jurassic (J) Jurassic

208 million Triassic Triassic

245 million Paleozoic Permian Permian Lopingian, Guadelupian

Cisuralian

Pensylvanian,

Mississippian

Late, Middle, and Early Devonian

Pridoli, Ludlow

Wenlock, Llandovery

Late, Middle and Early Ordovician

Furongian, Middle, Early

286 million Missisippian, Pennsylvanian

Carboniferous

360 million Devonian Devonian

408 million Silurian Silurian

430 million Ordovician Ordovician

505 million Cambrian Cambrian

550 million Neoproterozoic (Precambrian) Edicaron Not used

Evolution

• The idea that populations of organisms, and therefore species of organisms, change over long spans of time.

Next Slide: The first theory of evolution.

Lamarck’s Theory of EvolutionJean Baptise Pierre Antoine de Monet Chevalier de Lamarck:

The guy with the big name and the wrong idea!(Perhaps)

• Lamarck first came up with a theory of evolution (c.1802)

• Unfortunately his theory was wrong!• Lamarck believed that organisms could

inherit “acquired characteristics” through use and disuse.– Lamarckian Myth: “If a giraffe stretches its

neck to reach leaves all its life, it’s offspring will have longer necks.”

Lamarck’s reasoning…

• It seems sensible at first glance:– Muscles that you use a lot grow larger, if you

don’t use them they atrophy (get smaller)– It also makes sense that organs you don’t

need should gradually disappear– Even some fossil record suggest that unused

organs may get smaller or eventually vanish, (like human’s tail bone and appendix)

• The problem with Lamarck’s idea is the mechanism he proposed. It doesn’t work!

Disproof of Lamarck’s Hypothesis• If the idea of use and disuse were correct,

then preventing an organism from using a structure for several generations would cause that structure to atrophy (get smaller)

• Experiments have pretty much disproven Lamarck’s hypothesis:

• If you remove the tails of mice, they cannot use them. After several generations, mice with shorter tails should be born, but this does NOT actually happen.

• Therefore, Lamarck’s main hypothesis is incorrect, which makes his whole theory very unlikely…

But…

Perhaps Jean-Baptise Pierre Antoine de Monet Chevalier de Lamarck was a little bit right!

• The recent science of epigenetics shows that conditions during your lifetime can switch genes on and off, and that some of these changes may be passed on to descendants.

In biology, the term epigenetics refers to changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence, hence the name epi- (Greek: over; above) -genetics. These changes may remain through cell divisions for the remainder of the cell's life and may also last for multiple generations. However, there is no change in the underlying DNA sequence of the organism; instead, non-genetic factors cause the organism's genes to behave (or "express themselves") differently.

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Charles Darwin andAlfred Russel Wallace

• In 1858 two different people (Darwin and Wallace) independently suggested a better theory of evolution.

• Darwin published a more complete version of the theory the next year*, along with evidence he collected in the Galapagos Islands, so he is generally credited with the idea.

* On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, was published November 24, 1859. Title was later shortened to The Origin of Species.

Darwin’s Hypotheses

• Descent with modification– Organisms change slowly over

time.– Newer species are the modified

descendants of older species.

• Modification by Natural selection.– The main reason that gradual

modifications occur is due to Natural Selection.

• The population of a species will increase exponentially, until some environmental factor limits it.

• When there is a limiting factor, not all members of the species will survive to reproduce.– There is competition for food, space, mates etc.– Only the members who are successful competitors

will survive to reproduce.– The genetic traits that allow an organism to survive

are called its “fitness”.– The survivors are said to be “adapted” to the

environment

Natural SelectionNatural Selection

The strength of Darwin’s Theory

• Darwin’s theories of evolution have been rigorously examined for over 150 years.

• Although many minor changes have been made to these theories to accommodate new discoveries, the two most basic of Darwin’s concepts continue to be valid:– 1) That species change over time.– 2) That the main cause of this change is

natural selection.

Internal Evidence of Evolution(comes from studying the biology of organisms)

• Homologous Structures:– Related organisms have structures that come from

similar sources* , (eg flipper of a seal and hand of human)

• Vestigial Structures:– Organisms have the remains of organs that serve

little value at the present time (eg: human appendix and “tail bone”)

• Similarities in Embryos:– The embryos of different organisms look very similar– “ontogeny recapitulates phylogeny”

• Similarities in DNA and proteins:– Many organisms have similar biological chemicals– DNA similarity is so closely linked to evolution that it is

now used trace the evolution of some organisms.*don’t mix homologous structures with analogous structures, which are similar

in appearance but different in origin.

Haeckel’s Controversial “Ontogeny Recapitulates Phylogeny” Drawing

Although many of Haekel’s ideas have been rejected by modern biologists as oversimplified, it is still a fascinating fact that the fetus of an organism shows evidence of its evolutionary ancestry.

External Evidence of Evolution(comes from studies of other areas of science)

• The fossil record shows changes over time– The organisms of today are different from the

fossils of the past– The older the fossils are, the more differences

there are (in general).

• Changes in populations of species have actually been observed in historic times.– Eg. Manchester Peppered Moths.

The Peppered Moths(Industrial Melanism)• 1848 peppered moth

population near Manchester• 98% light mottled moths• 2% dark moths

• 1895• 5% light mottled moths• 95% dark moths

Clearly, some type of evolution is at work here.

In just 50 years a rare moth mutation has become the typical variety of moth.

Why ?

• If you were a bird who ate moths, which of the moths in the picture below would you catch?

You would probably catch the one that you can see. In 1848, most of the trees around Manchester were covered in light lichens, which camouflaged the more common coloured moths.

Easy to see

Harder to see

• During the 50 years that followed 1848, the industrial revolution came to Manchester. The lichens died from pollution, and the trees became darker from soot. Now which moth would you spot?

Easy to see

Harder to see

• Because the peppered moth population change can be cited as proof that evolution occurs, it has been very controversial.– Proponents use the extensive studies as

proof that the changes in a population can occur as the result of natural selection.

– Opponents point out that the photos I showed you were “staged”, therefore question if moths would ever naturally settle on oppositely coloured trees.

Patterns in Evolution

• Coevolution– Two different organisms evolve in close relationship

to each other.

• Convergent Evolution– Several different species adapt to the same

environment. Eventually they show similar features (but they never become the same species)

• Divergent Evolution– AKA Adaptive Radiation. One species adapts to fit

several different environments. Eventually it divides into different species.

Chapter 16: Evolution of PopulationsChapter 16: Evolution of Populations

• In this chapter we will look at populations and how they vary and how they spread genes.

• We will look at mutations, and the effect they have

• We will study speciation, the development of new species.

Population Genetics

• Population genetics is the study of evolution from a genetic point of view

• A population is group of similar organisms

Variation

• Within a population there is always variation. Some organisms are a bit taller or shorter, a bit faster or slower, a bit stronger or weaker, etc.

Causes of Variation

• Environmental causes of variation– Better food, growth conditions– Injuries

• Genetic causes of variation– Mutation (changes in genes)– Recombination (separation of genes in

meiosis)– Random breeding and fertilization

Very Important

to Evolution.

Not so important to evolution

Hardy-Weinberg Principle

• Gene frequencies will not change if ALL of the following are true:– No mutations occur (no radiation or mutagens)– There is no migration (no one leaves or arrives)– Population is very large (ideally infinite)– Individuals mate randomly (no preferential mating)– Natural selection does not occur (no competition)

• In other words, evolution would not happen in an ideal world.

In the Real World, Evolution Occurs

• Mutations do happen– Changes occur to genes as the result of

radiation, chemicals or random events

• Migration does happen– Individuals arrive and leave populations,

changing the genetic makeup of the population

• Populations are finite in size– Small populations allow “genetic drift” to

occur, as allele frequencies change.

• Mating is not always random– Some animals compete for mates, or have

rituals that determine who mates (eg. Only the alpha wolf mates)

• Natural Selection does occur– There is competition for resources in most

populations. The survivors are the ones who reproduce.

Types of Natural Selection

• Stabilizing– Most survivors are similar. The average is favoured,

unusual individuals seldom survive

• Directional– Most survivors have a particular feature. Individuals

without the feature seldom survive.

• Disruptive– Either of two extremes is favoured. Average individuals

seldom survive

• Sexual– Mates are chosen by a particular feature. Individuals

without the feature seldom reproduce.

Chapter 17: Human EvolutionChapter 17: Human Evolution

Hominid Fossils

• Humans and some of their extinct relatives belong to a family known as hominids.

• Hominids are classed within the order primates, along with apes and monkeys.

• The oldest hominid fossils have been found in Africa.

“Lucy” a hominid fossil from About 3 million years ago

• The complete classification of humans is:– Kingdom Animalia (animal kingdom)

– Phylum Chordata (chordates have a notochord)– Subphylum Vertebrata (with proper backbone)

– Superclass Tetrapoda (decendants of four-limbed vertebrates)

– Class Mammalia (the mammals)– Subclass Theria (live-birth mammals),

– infraclass Eutheria (placental mammals)

– Order Primates (the primates: monkeys, apes, hominids)– Superfamily Hominoidae (anthropoids, greater apes)

– Family Hominidae (the hominids: humanlike. All other hominids except humans are now extinct)

– Genus Homo (Humans and early humans)

– Species sapiens (Modern “wise” humans)

This is presented for your information. You don’t need to copy or memorize it

Some Identified Hominid Species

• Australopithicus afarensis “Lucy” is a species found in the Afar valley of Africa. They lived between 3 million and 4 million years ago

• Australopithicus africanus, Taller and heavier than “Lucy” lived in Africa between 2.3 and 3 million years ago

• Paranthropus* robustus and Paranthropus* boisei “nutcracker man” both lived between 1 and 2 million years ago in Africa* These two were formerly placed in genus Australopithicus

Australopithicus

Paranthropus

A newly identified hominid

• Ardipithicus ramidus (Ardi): a chimpanzee sized hominid found in Africa and dated to about 4.4 million years, making it the oldest nearly intact hominid skeleton ever found.

On October 1, 2009, paleontologists formally announced the discovery of the relatively complete A. ramidus fossil skeleton first unearthed in 1994. The fossil is the remains of a small-brained 50-kilogram (110 lb) female, nicknamed "Ardi", and includes most of the skull and teeth, as well as the pelvis, hands, and feet

More Identified Hominid Species• Homo Habilis “Handy Man” lived in

Africa about 2.5 million years ago. This fossil used tools and may be the earliest representative of the human genus.

• Homo Erectus, “upright human” was first discovered in Java (nicknamed Java man), and since then all over Asia, Africa and Europe. This may well be the ancestor of modern humans. They existed from 1.8 million years ago to as recently as 40,000 years.

Two Modern Human Species

• Homo neanderthalensis (or possibly Homo sapiens- neanderthalensis) lived in Europe from about 1.8 million years ago to as recently as 30,000 years ago. It has not been established if this was a separate species of human, or a “sub-species” that would be capable of breeding with “modern” humans (hence the disputed classification)

The most recent evidence is that these two types of human were different species, so I will use the terms homo sapiens and homo neanderthalensis

• Homo sapiens (or perhaps Homo sapiens sapiens) is the designation of modern humans. The first fossils of modern humans were found in the Cro-magnon caves in southern France.

Because of where they were first found, early homo sapiens are occasionally referred to as “Cro-magnon man”. This is not an official designation, as they were undoubtedly the same species as modern man.

Some lesser-known and disputed hominid fossils

• Homo Floresiensis? “hobbit”: a very small hominid fossil recently found in Malasia dating to about 13000 years ago. Its authenticity is still under dispute. It may be a malformed human.

• Homo Heidelburgensis “Goliath” is a large fossil homind found in Germany. It may be a separate species or a variety of Neanderthal, Homo Erectus or Antecessor

• Homo Antecessor is a fossil found in Spain which may be an ancestor of both Neanderthals and modern humans, or it may simply be a variety of Neanderthal or Homo Erectus

Homo Sapiens Homo Erectus (Homo Heidelbergensis)

Homo Habilis (Homo Floresiensis) Paranthropus Boisei Neanderthal

Probable Brain Sizes 500 cm3 700 cm3 1000 cm3 1450 cm3 1400 cm3

He thinksHe’s so Smart!

Chapter 18: ClassificationChapter 18: Classification

• What is a species?

• What is Taxonomy?

• What was Linnaeus’ System and the seven original levels?

What is a species?• Textbook definition:

“A species is a group of organisms of a single type that are capable of producing fertile offspring in a natural environment.”

• But all definitions of species are controversial, especially for extinct species where we cannot test breeding ability.– Everybody accepts the idea that members of

the same species look similar and can mate with each other. The problems are in the details– How similar? How successful is the mating? How productive are the offspring?

What is Taxonomy?

• Taxonomy is the science of classifying things. In biology this refers to organizing species into different groups.

• This can sometimes be quite difficult.– Taxonomists often make judgement calls

when grouping organisms into categories. Other taxonomists may later disagree and reclassify the organisms.

Who was Linnaeus and what was his system?

• Carolus Linnaeus (1707-1778) was a Swedish scientist who grouped living things into hierarchical categories.– “hierarchical” means at different levels

• The seven levels Linnaeus created were:– Kingdom: Highest level, eg. Animals (vs. plants)– Phylum: 2nd level: eg. Chordates (vs. invertebrates)– Class: 3rd level: eg. Mammals (vs. reptiles, birds, fish) – Order: 4th level: eg. Carnivores (vs. marsupials, whales)– Family: 5th level: eg. Canines (vs. cats, seals, weasels) – Genus: 6th level: closely related species, eg. wolf & dog– Species: most specific level, eg. Canis familiaris

Binomial Nomenclature• Linnaeus also introduced the method of

scientific naming called binomial nomenclature.– He identified each organism by using a

combination of its Genus and Species name.– He made sure that no two creatures had the

same combination of genus & species name.– He used Latin (widely read by educated

people at that time)– The genus name was always a Latinized

noun, the species name was a Latin adjective.

Categorizing Life• Linnaeus based his system on observable

characteristics, and assumed that seven levels would be enough.

• Since then we have added many other ways of grouping organisms, including:– Systematics (Phylogeny) – Organized on the

basis of evolution, using phylogenetic trees – Cladistics – Organized on the basis of derived

characteristics, using cladograms– Genetics – Organized on the basis of

similarities in DNA

A Phylogenetic Tree

• A phylogenetic tree shows the presumed relationship between organisms and their common ancestors

• See another example on page 343

Cladogram

• A cladogram is similar to a phylogenetic tree, but each division is limited to two branches based on a specific derived feature.

• Another example on page 346

Genetics (DNA)• Study of the similarity of DNA of

organisms allows geneticists to estimate the time since two organisms had a common ancestor.

• For example, humans and chimpanzees had a common ancestor about 5 million years ago, based on DNA similarity.– When all we had were fossils, most

palaeontologists assumed humans & chimps diverged 25 million years ago. Now we believe it was much more recent.

How many kingdoms?

• Since Linnaeus’ time there has been frequent debate about how many kingdoms are needed…

• Linnaeus recognized two: plants & animals• Later, we separated the fungi from plants• When microscopic organisms were

discovered we added kingdom protista. • With bacteria we first added monera, • But then divided monera into eubacteria

and archaebacteria

Development of Kingdomsfrom 1735-2000

Linnaeus1735

2 kingdoms

Haeckel1866

3 kingdoms

Chatton1937

2 empires

Copeland1956

4 kingdoms

Whittaker1969

5kingdoms

Woese etc.1977

6 kingdoms

Woese etc.1990

3 domains

Cavalier-Smith2004

6kingdoms

Protista Prokaryota Mychota Monera Eubacteria Bacteria Bacteria

archeabacteria Archaea (Archeabacteria)

Eukaryota Protoctista Protista Protista Eukarya Protozoa

ChromistaVegetabilia Plantae Fungi Fungi

FungiPlantae Plantae PlantaePlantae

Animalia Animalia Animalia Animalia AnimaliaAnimalia

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Optional EnrichmentCarl Woese and the importance of microscopic life.

• Carl R. Woese is famous for shaking up our idea of kingdoms in the 1980s. While studying the ribosomal DNA of bacteria he became convinced that there was an important division within bacteria that occurred long before the rise of eukaryotic cells. He suggested that life should be divided into three domains instead of six or seven kingdoms. Even today, his research remains controversial, but it does point out that evolution was important to early bacteria.

Many biologists now add his domains as an extra level of

classification above kingdoms

Woese’s tree of life.

The Six Kingdoms

• Kingdom Archaebacteria (AKA. Archae, formerly part of Monera)– Unicellular, prokaryotic bacteria of

ancient origin– Include methanogenic and

chemosynthetic organisms

• Kingdom Eubacteria (AKA. Bacteria, formerly part of Monera)– Unicellular, prokaryotic bacteria of

more recent origin.– Include most common bacteria.

• Kingdom Protista (the “protists”)– Eukaryotic organisms (have cells with true

nucleus and organelles)– Most are single celled and microscopic

• but some are multi-cellular but with little differentiation, including a few very large seaweeds

• Most are heterotrophs, meaning they feed on other organisms (the protozoa); but a some are photosynthetic autotrophs with chlorophyll (the algae)

Proposed Change to Kingdom Protistac. 2004

• It has been said that kingdom protista had become a dumping ground for all organisms that don’t belong to one of the other kingdoms, so in 2004 it was proposed to divide it into 2 kingdoms.

• Kingdom Protozoa: the animal-like protists

• Kingdom Chromista: the algae and seaweeds (plant-like protists).

Why are giant seeweeds considered to be protists (or perhaps chromista) instead of plants?

• Seaweeds look like plants and have many features of plants– They have photosynthesis and are greenish– They are multicellular– They have cell walls and large vacuoles

• But… biologists now think that they evolved separately from plants– They both came from simple algae, but along different

branches of a phylogenetic tree.– Seaweeds have fewer tissues or organs than plants– Genetically, seaweeds are closer to algae than to

plants

• Kingdom Fungi (all the fungus)– Heterotrophic (no photosynthesis)– Unicellular and multi-cellular (microscopic to

very large)– Most have cell walls (like plants) but lack

chlorophyll. Many are multi-nucleate.– Includes molds, mildews, rusts, smuts,

mushrooms, puffballs, morels, truffles, and any other types of fungus.

• Kingdom Plantae (the plants)– Nearly all plants are autotrophs

(make their own food)– Multi-cellular, and some can

grow quite large. (100m tall Sequoias and Douglas firs)

– Nearly all plants use photosynthesis as their main source of food.

• Pitcher plants and Venus Fly Traps get extra nutrients from insects.

• Kingdom Animalia (the animals)– Multicellular organisms– Heterotrophic (they eat other food)– Varied body types, including:

• Sponges, jellyfish, worms, mollusks (clams, squids, snails) worms, arthropods (including: crabs, spiders, insects), vertebrates (including: fish, amphibians, reptiles, birds, mammals)

The Domain System

• Some taxonomists have suggested that we replace Linnaeus’ system of kingdoms with three “Domains”– Domain Bacteria (= Kingdom Eubacteria)– Domain Archaea (= Kingdom Archaebacteria)– Domain Eukarya (Plants, Animals, Fungi, Protists)

• So far, this has NOT caught on!

Archeabacteria Eubacteria Protista Fungi Plantae Animalia

Current system Δ Proposed system▼

Archaea Bacteria Eukarya

Extra Levels of Taxonomy(don’t try to memorize)

Domain Magnorder

Superkingdom Superphylum Superclass Superorder Super-family

Super-species

Kingdom Phylum orDivision

Class Order Family Genus Species

Subkingdom Subphylum Subclass Suborder Subfamily Sub-genus

Subspecies

Branch Infraphylum Infraclass Infraorder Infrafamily or Tribe**

Infraspecies

Microphylum Parvclass* Parvorder Alliance**

Exercise

• Using the keys on pages 1092-1099, classify the following organisms:– A duck– A mushroom– A seahorse– A snake– A rose– A moss– An oyster– An octopus– A wasp– A lobster

For some you can just find kingdom and phylum, some you can classify down to order.

Classification

kingdom Phylum Class Order

Animalia Chordata Aves Anseriformes

Fungi Basidiomycota Basidiomycetes Agaricales

Animalia Chordata Osteichthyes Sygnathiformes

Animalia Chordata Reptilia* Squamata

Plantae Anthophyta Dicotyledones Rosales

Plantae Bryophyta Bryidae Polytrichales

Animalia Mollusca Bivalva Filibranchia

Animalia Mollusca Cephalopoda Coleoidea

Animalia Arthropoda Insecta Hymenoptera

Animalia Arthropoda Crustacea Decapoda

*in some taxonomies, Reptilia has been replaced by Sauropsida

The Reptile vs. Bird Controversy

Should reptiles and birds be separate classes? According to cladistics, no, but according to systematics (phylogeny) and tradition, yes they should.

The trouble, it turns out, is that birds are far more closely related to reptiles than we used to think, but most people still don’t want to call birds reptiles!

Most people still use the term “class reptilia” for reptiles and “class aves” for birds, but a few taxonomists use “class sauropsida” for both birds and reptiles together.

Bird vs. Reptile

PhyloCode• A new system of taxonomy, called International

Code of Phylogenetic Nomenclature, or PhyloCode for short, is currently being drafted.

• It is intended to replace the Linnaean system that we have used for the last 250 years with a new way of looking at taxonomy.

• The current system will continue to exist as a “rank based system” for a long time to come.

• PhyloCode is currently in its fourth draft, and it has not yet been implimented. For the text of the fourth draft visit the website: http://www.ohio.edu/phylocode/toc.html. Although it will soon be used by biologists, it is unlikely to ever be used widely by the general public.