Biodiversity and conservation

Genetic diversity: within species variation (e.g corn [Zea mays] in North vs. Central America)

Species diversity: species richness

Ecosystem diversity: variety of habitats

Basic questions in biodiversity research:

for any plot of land (or patch of sea)

• Why does it contain this many plant and animal species, and not more, or less?

• Why is species Y common and species X rare?

The standard answer:

• “it depends on the # of available niches”,

OR “it depends on….”:• Availability of resources / intensity

of competition, predation, infection, etc.

The ‘neutral’ answer*:

• It depends on chance!• Diversity = f(immigration, extinction, evolution)

• Consider the example of a patch of tropical forest in Panama - how many tree species will it contain?

*Hubbell, S.P. 2001. The unified neutral theory of biodiversity and biogeography, Princeton U.P.

Tree diversity of a Panamanian forest

Satellite image of Barro Colorado Island, Panama (Image: NASA);Map source: www.geographic.org, used with permission

How many treescan island sustain?

How diverse is theforest “reservoir”?

Immigrationrate?

How fast are newtree species evolving?

Testing Hubbell’s model on Barro Colorado

Patterns of biodiversity

1. Latitudinal gradient in species richness

Global species richness(composite index)

Hotspots

div

ers

ity g

radie

nt

Biodiversity as a function of latitude(North and Central America)

Birds Beetles Ants

Labrador 81 Labrador 169 Alaska 7

New York 195 Massachusetts 2000 Iowa 73

Guatemala 469 Florida 4000 Trinidad 134

S. Florida

North America

Diversity of North

American tree

species

Biodiversity gradients (tree species) in temperate coastal evergreen

forests

Biodiversity gradients in the temperate coastal evergreen forest of North

America

Ranges of newts and

salamandersin the

temperateevergreenforests of western North

America

Patterns of biodiversit

y

2. Altitudinal gradient

Altitudinal gradients

in bird species diversity

Species richness

andtemperatur

e range

Birds

Mammals

Snails

Biodiversity and moisture availability

Ants

Rodents

Species richness and productivity

N. American data

Habitat complexity(e.g. # of forest strata)

Low complexity(single stratum)

High complexity(multi-strata)

approx. equivalent tree species richness

Species diversity and habitat complexity

Conservation of biodiversity

• Are we engaged in a “biotic holocaust”?

• How many species are currently being lost?

• Why is biodiversity important?• How can species conservation be best

achieved?

Conservation of biodiversity

Extinction - the demise (locally or globally) of a species;Endangered species - a species or subspecies that is at risk of extinction throughout all or part of its range;Threatened (or vulnerable) species - possibly at risk of extinction in the near future

Species under threat: endemics:

(e.g. Hawai’ian honeycreepers)

• Generally very small populations

• At risk from habitat loss and introduction of aliens (particularly predators)

Island endemics under threat

• ~4 000 endemic or native plant and animal species live in the archipelago (cf. ~100 in British Isles).e.g. Canary Islands

Canary Islands endemics

• On average a new species invades every 17 days; a new serious pest invades on average every 6 months.

• Most problematical pests are the Barbary ground squirrel, the Corsican mouflon, and most recently, a beetle (“picudo rojo”), that feeds on native palms.

• 20 endemics are considered endangered; several have <100 individuals left.

Source: New York Times, Aug. 29, 2006, p. A4

Species under threat: widespread species and range

collapse

Population collapse is generally accompanied by (or caused by) range collapse (e.g. American bison; giant panda; black-footed ferret).

In most cases marginal populations, which may have distinctive genomes, are the only survivors.

What is the current extinction rate?

Very difficult to demonstrate that a species is truly extinct (e.g. the ivory-billed woodpecker of the SE USA) so estimates of modern extinction rates vary widely.

Colinvaux notes that the rate is “incalculable”;

Myers (1979) says “we have no way of knowing … let alone an approximate guess”.

Biotic holocaust?Extreme estimates of current annual species loss: 40,000 (Myers, 1979) widely cited in 1980-90’s (e.g. by Al Gore) 27,000 - 100,000* (Wilson, 1992) *20% of all species gone by 2020! 250,000** (Ehrlich, cited in Stork, 1997) **all species gone by 2010-2025!

Sources for previous estimates

• Myers, N. 1979. The Sinking Ark. Pergamon Press.

• Wilson, E.O. 1992. The Diversity of Life.

• Stork, N.E. in: Wilson, E.O. et al., 1997. Biodiversity, pp. 41-68.

Alternative estimates• A much lower estimate of ~1400

extinctions per yr (=0.7% in 50 years) was derived by Lomborg (1998). This is still ~1500 times greater than estimated “background” rates from geological data

Lomborg (1998) The Skeptical Environmentalist: Measuring the Real State of the World. Cambridge U.P.

Modern extinctions: a fishy example

In the Nearctic realm 1033 species of fish are known to have inhabited streams and lakes in recent historic times. Of these, 27 (3%) are thought to be extinct, and 277 (28%) are endangered or vulnerable. The factors that caused these declines are habitat destruction, introduction of alien species, pollution, hybridization and over-harvesting.

Forest fragmentatio

n:Wisconsin

(1830-1950).

Area: 100 km2

1830 1882

1902 1950

shaded = forest white = agriculture

(prairie in 1830)

Forest fragmentation: Bahia (coastal S. Brazil)

dark = forest; light = agriculture

Habitat loss and extinction: model

predictions

Galapagos

• 99% of primary forest of eastern US lost from 1800-2000; only one bird species extinct (Simberloff)

• 88% of forest along Atlantic coast of Brazil cleared in same period; none of the 171 animals have gone extinct (Brazilian Soc. Zoologists).

• See Lombock (1998) for discussion of these and other examples

How many species have gone extinct as a result of diminished habitat

area?

Slo

w r

ela

xati

on t

o a

new

eq

uili

bri

um

wit

h c

han

gin

g

isla

nd a

rea

Forest fragmentation: Rondonia, Brazil

1975 1992100 km2

Forest fragmentation experiment, Amazonas

Thomas Lovejoy, Smithsonian Institute

Mammals* in rain forest fragments

0

5

10

15

20

Mammals

Intact forest

10 ha fragment

1 ha fragment

* These results are from trapping experiments and do not include bats and nocturnal canopy species. In intact forest 9 spp. were common; in 10 ha fragments, only one; in 1 ha fragments, all mammals were “uncommon”.

Data from Lovejoy et al. (1984); in Nitecki, M.H.“Extinctions”. Univ. Chicago Press

Why conserve?

• Intrinsic and aesthetic value of species (mosquitoes?)

• Economic value (gene pools, untapped riches)

The rewards of conservation

0102030405060708090

100

1500's 1600's 1700's 1800's 1900's

Bird species

SavedExtinctions

*

*Global data; Source: New York Times Aug. 29, 2006; p. D3

Some of the saved

Chatham Island taiko Lear’s macaw

California condor Mauritius parakeet

Mauritius kestrel

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Species conservation: the task ahead

“The threat ahead is massive. It’s like we’ve ridden our first wave on a surfboard and feel good about it, but look back and there’s a tsunami coming in.”

Dr. Stuart Pimm, a conservation ecologist at Duke University, quoted in the New York Times, Aug 29, 2006, p. D3.

How conserve?

• Zoos and captive breeding (e.g. condors)

• Predator control (e.g. Chatham Is. taiko)

• Habitat preservation / restoration(e.g. Mauritius parakeet) for its own sake, or combined with sustainable economic diversification (e.g. turtle harvesting vs. cattle farming on the Amazon floodplain; the former retains the galeria forest).

• Compensatione.g. ranchers in Wyoming [for cattle killed by wolves]; farmers in Bahia, Brazil [for corn eaten by Lear’s parrot]

Predator control

Eradication scorecard (# island removals)e.g. mammals (all alien) have been eradicated on 68 of the 168 islands

in New Zealand; 41 introduced mammal populations have been eradicated on 27 islands off the Pacific coast of Mexico. Native plant and animal species have rebounded following eradications.

Source: Krajick. K. 2005. Science 310, p. 1410-1413.

Pre

Post

Predator control -> habitat restoration

e.g. removal of goats on Santiago Island (Galapagos) leads to recovery of native vegetation.

Source: Krajick. K. 2005. Science 310, p. 1410-1413.

Pre

Post

goat exclosure

Species need

space!

How big a fragment would conserve 95% of

the species over a 50-yr period?

Ans. = 100,000 ha.

[100 km x 100km!]New Scientist 8-14 November, 2003, p.15;

Based on surveys of avifauna in Amazonas

Applications of island

biogeography theory to

habitat conservatio

n

Good choice Poor choice

Corridors and conservation

• Experiment to determine effects of corridors between open patches on plant biodiversity in longleaf pine (Pinus palustris) forest in South Carolina. Patches created in 2000.

Source: Dametsch, E. et al., 2006. Science 313, 1284 - 1286

Corridor experiment results

Source: Dametsch, E. et al., 2006. Science 313, 1284 - 1286

Connected patches have ~20% more plant spp. than unconnected

patches; few weedy exotics

Do the ecological

reserves in BC display these

principles?

Goosegrass Creek(Kootenays)

E.R. #55

Haynes Lease(Okanagan) E.R. #100

1 km

Future challenges: climate change

In alpine areas timberline is creeping upwards by a few meters per decade; alpine species are therefore occupying smaller and smaller refuges. In NZ, for example, it is predicted that 80% of alpine islands will be wiped out in this century, and 200-300 alpine plant species will go extinct*. How do we develop conservation strategies that are nimble enough to deal with climate change?

*Halloy, S.R.P., and Mark, A.F. 2003. Arctic, Antarctic, and Alpine Research, 35, 248-254.

A more local example of this problem….

Lassen Peak, northern California

1930

2006

Subalpine rodents, (e.g. Zapus spp.) are now found 700m higher than they were a century ago; the altitudinal ranges of Alpine chipmunks and pikas have shrunk correspondingly

Pacific jumping mouse(Zapus trinotatus)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Pika(Ochotona princeps)

Graphics: NY Times (Nov. 7, 2006); Wikipedia