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