biodiversity patterns, practicality & preservation
TRANSCRIPT
BIODIVERSITY
Patterns, Practicality
&
Preservation
LEVELS OF DIVERSITY
• ECOSYSTEM
LEVELS OF DIVERSITY
SPECIES
LEVELS OF DIVERSITY
• GENETIC
How many species are there on Earth?
• Formally described (means written up in a scientific publication, identified as new and placed in a taxonomic category):– 1,750,000 (roughly)
• Many groups well known – Which ones? Why?
• Others much more poorly known– Fungi, arthropods, nematodes, etc
• Estimates for the real number?
How estimate??
• Explore new areas and collect organisms– What fraction of the collected organisms are
new?• If low, eg, 2 of 100 insect specimens are new to
science, then estimate that most of the insects in that area are already known.
• If high, eg 44 of 100 insect specimens are new to science, then estimate that many new species are waiting to be discovered and estimate of total insect species in the area must be high
Arachnophobia
Hotspots:area with large number of endemic species
area has lost >70% of its habitat
• 70 percent of the world's species are in 12 countries:
• Australia, Brazil, China, Columbia, Ecuador, India, Indonesia, Madagascar,
Mexico, Peru, and Zaire.
• Oops….Costa Rica
Biodivrsity patterns: hotspots
What exactly is a species?
• A species is all individuals that can interbreed freely in nature and produce fertile offspring.
Richness vs. evenness
• Species richness: the overall number of species in a defined area
• Species evenness: Uniformity of abundance. Also called ``equitability’’– Greatest when all species present are equally
abundant
Richness vs. evenness
• 2 habitats with 100 organisms
• A: 10 species, 10 individuals of each species
• B: 10 species, 91 individuals of one species and one each of the other nine.
• A and B are EQUALLY RICH
• A exhibits GREATER EVENNESS than B
Measuring biodiversity
• D =Sum (n / N)2
• n= number of individuals of a particular species
• N= number of indivduals of all species• Simpsons index of diversity = 1-D• (D measures the probability that two
individuals selected from a sample belong to the same species)
• Peru: 1,804 spp birds
US, Canada, Europe:
~1,900 spp birds
Where are the species?
Where are the species?
• One hectare of Amazon rain forest (about the size of a standard football field):– More tree species than
are found in all of Europe
• Amazon: > 750 spp in a single hectare
• North America: about 1,000 species
• Europe: < 800 spp.
Benefits of biodiversity?
Why are species endangered?
Why are species endangered?
• 1: habitat loss
» Rangeland in the Amazon, still smoldering after being cut and burned
tat
• Habitat fragmentation as suburbs encroach on farmland
Habitat loss
• As habitat is lost, edge come to predominate over interior.
edge
interior
KEY POINT
• Fragmentation – The breaking up of a once-contiguous landscape (wild habitat) into “islands” of habitat surrounded by human development.
Amazon rainforest
• One main road into the forest leads to many illegal roads and settlements.
• Result is fragmentation of the forest.
Prairie potholes•
•
Prairie pothole, southern Albertasummer, 2011
Why are species endangered?
• 2: Invasives
What do invasives do?
• Change habitat– Fungus that causes Chestnut blight– Zebra mussel filters huge amounts of water,
reducing plankton abundance
• Prey on– Brown tree snake on Guam has nearly wiped
out the island’s birds
Why are species endangered?
• 3: Pollution• DDT
• Threat to raptors
DDT was banned
in US
Why are species endangered?
• 4: Hunting/poaching/harvesting• Often affects species already threatened by
habitat loss or other factor
• Elephants – poaching
• Rhinos – poaching
Why are species endangered?
• 5: Climate change• Polar bears: the sea ice they depend on is
melting sooner and more extensively each summer
• Sea Turtles: nests on some beaches are threatened by rising sea levels (the turtles may not find suitable nest sites as the sea moves inland).
Protecting biodiversity: Laws
• Endangered Species Act
• CITES – Convention on Trade in Endangered Species of Fauna and Flora
Endangered Species Act• Signed into law by Nixon, 12/28/73• Key agencies: US Fish and Wildlife Service (USFWS)
and National Marine Fisheries Service (NMFS) • Requires federal agencies, in consultation with USFWS
and NMFS, ``to ensure that actions they authorize, fund, or carry out are not likely to jeopardize the continued existence of any listed species or result in the destruction or adverse modification of designated critical habitat of such species.’’
• TRANSLATION: the agencies have to make sure that listed species (threatened or endangered) are not threatened with extinction.
Listing
• USFWS or NMFS can list
• Citizens can petition for a species to be listed.
Critical habitat
• All listings under the ESA must include critical habitat.
• Habitat that is deemed essential to the continued existence of the species and is therefore protected.
Private land• Much critical habitat is privately owned• What to do?• Incentives for private landowners to preserve
habitat, by allowing them to continue to get economic benefit from their land or not be penalized if endangered species shows up.
• E.g. Pine woods of NC and SC– Maintain fire
– Allow trees to grow
Takings
• The law also prohibits any action that causes a "taking" of any listed species of endangered fish or wildlife.
CITES
• International agreement
• Went into force in 1975
• Goal: ensure that trade in endangered species or their parts doesn’t threaten their survival.
CITES
• Roughly 5,000 species of animals• 28,000 species of plants• Appendix I: species that may become extinct and
are threatened by trade– Gorillas, chimpanzee, tiger, elephant
• II: many more species, not immediately threatened, but could become so if trade not restricted.– Great white shark, African gray parrot
• III: requested to be listed by individual countries
Extinction• Two kinds:1. Background: the regular, consistent,
extinction of species over millions and hundreds of millions of years
- Result of environmental change, species interactions
2. Mass: the relatively sudden extinction of a great number of species in a short period of time (few million years, or less)
This graph shows extinction rates. You can see that five times in the last 600 million years, the rate has spiked up. Those are MASS EXTINCTIONS. The last one is when the dinosaurs died. Between mass extinctions, there is a more steady extinction rate, called BACKGROUND EXTINCTION.
•
Date of extinctionmya=million years ago
% species lost Species affected
65 mya
Cretaceous
85 Dinosaurs, plants (except ferns and seed bearing plants), marine vertebrates and invertebrates. Most mammals, birds, turtles, crocodiles, lizards, snakes, and amphibians were unaffected.
213 Triassic 44 Marine vertebrates and invertebrates.248
248 Permian 75-95 Marine vertebrates and invertebrates.380
380 Devonian 70 Marine invertebrates
450-440
Ordovician
50 Marine invertebrates
6th mass extinction?
• We are in the midst of a 6th mass extinction.
• First one caused by human activity.
Evidence for 6th mass extinction
• Birds: very well studied group, with a good fossil record
• Background extinction rate 1 species per 100 years
128 extinctions in last 500 years
103 extinctions in last 200 years
• 1,186 of about 9700 bird species are threatened