Helpful Web Sites http://www.wa.gov/wdfw/ (Wa. Dept. of Fish and Wildlife home page) http://www.nceet.snre.umich.edu/EndSpp/factsheet.html (fact sheets on

endangered species) http://thomas.loc.gov/home/thomas2.html (links to all legislation) http://www.fws.gov/r9endspp/endspp.html (USFWS Endg. Spp. Home

page) http://web.lexis-nexis.com/congcomp (Access to federal register) http://www.fws.gov/laws/digest/digest.html (USFWS law descriptions) http://www.endangeredspecie.com/ (info source for species and pubs) http://www.umich.edu/~esupdate/index.html (Endangered Species

Update)

Rarity and Extinction

Why are some species rare? How do we classify rarity? Why are rare species prone to extinction? What is the historical pattern of extinction? Where is endangerment now occurring and

what are the causes?

Why are Some Species Rare? Body Size Trophic position Geographic distribution

– islands

– endemics

Degree of ecological specialization– niche width

Reproductive rate Recency of speciation

Classification of Rarity (Rabinowitz 1981)

Large Range Small RangeGeneralHabitatRequire-ments

SpecificHabitatRequire-ments

GeneralHabitatRequire-ments

SpecificHabitatRequire-ments

LocalPopulationsSomewhereLarge

BrownRat,Starling

RedMangrove

PygmyCypress

SilverSword

LocalPopulationseverywheresmall

PeregrineFalcon

Osprey Alala AlpineLilyGiantPanda

Why are Rare Species Prone to Extinction? Demographic Stochasticity

– By chance alone population fluctuates in growth rate and hence change in size from one year to the next

• The actual individuals that live and reproduce may be a random event

– When population is small, extinction can occur with relatively high probability even if chances of survival and successful reproduction are high

Why are Rare Species Prone to Extinction? Environmental Stochasticity

– random series of environmental changes that affect all members of a population similarly

– a couple of bad years in a row can be especially devastating to rare populations

• El Nino and Alala– Poor reproduction, even in captivity

– Compounding effect of predators (Io)

» specializing on crows more?

Why are Rare Species Prone to Extinction?

Catastrophes– Rare, but huge effects

Recent study by Spiller et al. (1998) quantified effects– Hurricane Lili hit Exuma Islands (Bahamas) in 1996 (first

since 1932)• high winds and 5m ocean surge

– Surveyed lizards and spiders on 19 islands before and after• 11 islands hit full on, 8 were protected by large island

Moderate Catastrophe Protected Islands

– lizards down 34%, spiders down 79% right after storm• Larger animals can weather moderate disturbances better

than small ones

– lizards did not increase appreciably during first year, but spiders did

• smaller organisms can rebound from catastrophe more quickly because of high reproductive rate

– Population size influenced likelihood of extinction in spiders

Major Catastrophe

Exposed Islands– All lizard and spider populations went extinct– Spiders rebounded within a year, lizards did not

recolonize in first year.• First colonist on Krakatoa was also a spider!

Why are Rare Species Prone to Extinction? Genetic Problems

– Difficulty Finding Mates– Genetic Drift

• Random Changes in Phenotype• Selection overruled

– Inbreeding Depression– Close “relatives” breed, heterozygosity goes down because they share

many alleles, semilethal recessives are expressed more frequently

– Decreased Genetic Variance• Novel solutions to environmental variability reduced

More Genetic Problems Reduction in Effective Population Size

– EPS = size of “ideal” population that looses genetic variation at same rate as does real population

– Variation is lost at 1/2N% per generation, and replaced at mutation rate per generation--this loss and creation usually balance out

– Loss is at > 1/2N% when sex ratios are not balanced, mating is not random, age distribution is not stable, population size is stable, and reproduction is not equal among breeders

Effective Population Size

0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20

Generation (t)

Het

eroz

ygos

itiy

(al

l po

pula

tion

s) Census population was n

= 16 flies In theory, given ideal

conditions, we would expect decline in heterozygosity to follow solid lines.

Data fits line with ideal population of n = 9, thus the Ne = 9, not 16

Theory, N = 16

Theory,N = 9

Data

H=2pq(1-1/2N)t, under idealconditions (theory)

Extinction Vortices Summarize the Interaction of

Genetic and Demographic Problems (Gilpin & Soule

(1986)

Environmental changes typically set up positive feedback loops between a population and its environment than accentuate impacts and may lead to extinction– R vortex– D vortex– F vortex– A vortex

R Vortex Basically compounding demographic

stochasticity– Low N leads to increased variation in r which makes

population vulnerable to further disturbances lowering N even more

– Low N could lead to skewed sex ratio which makes it difficult to find mates, which lowers reproduction, which lowers N even more, which skews sex ratio further, increasing difficulty, lowering reproduction, lowering N……...

D Vortex

Lower N affects spatial arrangement of population by increasing fragmentation and isolation of demes

Fragments of population are of very small size, so they decline faster, which increases isolation more and speeds decline faster

F Vortex

Population decline reduces Ne, which increases inbreeding which reduces population growth, lowering N further and increasing inbreeding further

A Vortex

Population decline reduces Ne and genetic variation which reduces a population’s ability to respond to changes in the environment (loosing race to see Red Queen)– this increases the lack of fit between population

and environment, which increases decline further, reducing ability to adapt further…..

Combined Vortices

All types of vortices feed off one another, greatly increasing probability of extinction in small populations– Population becomes fragmented

• each deme is now smaller and susceptible to demographic stochasticity (R vortex) and inbreeding (F vortex)

• species cannot adjust to environmental changes (A vortex), so population declines further making it more susceptible to demographic stochasticity (R vortex), which accentuates fragmentation…..

What is the historical pattern of extinction?

Five major mass extinctions through geologic time– Late Permian--formation of Pangea, loss of shallows, many

marine organism extinctions (Schopf 1974)

Loss ofDinosMostly

Marine

Shallows

(Myers 1997)

Causes of Historic Extinctions are Varied

Meteors Continental Drift Humans

– Pattern of extinctions during last 30,000 years (late Pleistocene) closely matches pattern of human colonization

Human Occupation of Earth

(Diamond 1998--Guns, Germs, and Steel)

Recent Extinctions are Most Common in Areas Recently Occupied by Humans

Colors indicate when significant extinction events occurred. Numbers indicate % of fauna that has goneextinct in last 100,000 years (Burney 1993)

Few Recent Extinctions, LongOccupancy byHumans

Recent OccupancyMany RecentExtinctions

So, Extinction is Natural, but Current Episode is Unusual Estimated to be 10 - 50 million species on earth

– Using 10 million, there are 5 million in tropical forests

– 2% of tropical forests are disappearing annually

– Translates into 27,000 species / year or 75 per day going extinct in tropical forests alone (Wilson 1992)

– This present rate is 10,000x greater than background rate through geologic time (Nott et al. 1995).

Continental extinction rates have increased from 10-7 to 10-4 species/species/year

Nott, et al. 1995. Current Biology 5:14-17

Global Change and Biodiversity

A Global Perspective on Endangerment Baillie’s (1996) analysis of the IUCN Red Data

Book Birds appear to be least threatened (at best facing a

10% risk of extinction in the wild in next 100 years)– 11% of world’s avifauna is threatened

– 25% of world’s mammals are threatened

– 20% of world’s reptiles are threatened

– 25% of world’s amphibians are threatened

– 34% of world’s fishes are threatened

(Pimm et al. 1995; Chapin et al 2000)

Vulnerable Orders Loss of all representatives of an Order would be

extreme pruning of tree of life Mammal orders at risk

– elephant, manatees, marsupial moles,opossum-like Microbiotheria --all species threatened

– horses, tapirs, rhinos; elephant shrews; monotremes; hyraxes; flying lemurs

Bird orders at risk– cranes, galliformes, parrots, doves, kingfishers & bee-eaters,

procellariiformes, grebes, kiwis, cassowaries

More Vulnerable Orders

Reptiles– tuatara, crocs, turtles are only groups well

surveyed and all have high level of threat (~40%)

Fishes– sturgeon & paddle-fish, coelacanth, minnows,

perch

Inverts– poor info, but mollusks top the list

Severity of Extinction 10% of all birds are threatened with extinction

– Not Random among families• Parrots, rails, cranes, pigeons, albatrosses, megapodes

– Low reproductive rates (Bennett and Owens 1997 Proc. Royal Soc. Lond 264:401-408)

– Should prioritize conservation efforts for these species

» (Hughes 1999. Bird Conservation International 9:147-154)

– Concentrated among island species• First colonists to pacific islands exterminated 50% of the

native birds

• Even worse on Hawaii—90-110 of 125-145 are extinct(Pimm et al. 1994. Phil. Trans. R. Soc. Lond. 344:27-33)

Geography of Vulnerability Mammals

– Indonesia (128), China and India (75 each), Brazil (71),………USA (35)

– Madagascar (44%), Philippines (32%)

Birds– Indonesia (104), Brazil (103), China (90)– Philippines (15%), New Zealand (15%)

Reptiles, Amphibians, Fishes, Inverts– Poorly assessed, but USA and Australia top the lists

Biodiversity is not evenly distributed across Earth5% of Earth holds 95% of most vulnerable bird species(Bibby 1994, Proc. Royal Soc. Lond.344:35-40.

US Patterns of Rarity, Endemism, Extinction, and Listings Dobson et al. 1997 Nature Serve 2000, 2002

– http://www.natureserve.org/index.jsp

“AtRisk”

Species at Risk

Endemic Species

Plant diversity, endemism, and rarity

5-4a,b,cSource: Precious Heritage (2000) © TNC, NatureServe

Vertebrate diversity, endemism, and rarity

5-6a,b,cSource: Precious Heritage (2000) © TNC, NatureServe

Distribution of Federally Listed Species

6-1Source: Precious Heritage (2000) © TNC, NatureServe

County Distribution of Federally Listed Species

6-2Source: Precious Heritage (2000) © TNC, NatureServe

Distribution of Imperiled Species by Ecoregion

Number ofSpecies

Number ofEndemic Imperiled Species

1-20

21-50

51-150

> 150

1-10

11-50

51-150

> 100

6-5Source: Precious Heritage (2000) © TNC, NatureServe

What Reasons are Listed For

Endangerment in US? (Czech and Krausman 1997)

Cause # EndangeredInteractions with nonnatives 305Urbanization 275Agriculture 224Outdoor recreation, tourism 186Ranching 182Water diversions 161Modified fire regimes,silviculture

144

Pollution of water, air, soil 144Energy exploration 140Industry and military 131

What Reasons are Listed For

Endangerment in US? (Czech and Krausman 1997)

Cause # EndangeredHarvest, intentional andincidental

120

Logging 109Roading 94Genetic problems (inbreeding,etc)

92

Wetland destruction 77Plant succession 77Disease 19Vandalism (destroy, but noharvest)

12

How Many Extinctions Have Been Documented in last 400 years?

Total of 611 totally gone, 30 more extinct in the wild()– Mammals 86 (3); 1.8%, most in Australia & West Indies– Birds 104(4); 1.0%, most in Mauritius, US, N Zealand– Reptiles 20 (1)– Amphibians 5 (0)– Fishes 81 (11)– Molluscs 230 (9); mostly gastropods on islands– Crustaceans 9 (1)– Insects 72 (1)– Other inverts 4 (0)

Extinctions

Evil Quartet (Diamond 1989)

Overkill– whales

Habitat Destruction and Fragmentation Impact of Introduced Species Chains of Extinction

– plants in Hawaii after loss of pollinators

Revisiting Threats

Habitat degradation/loss Alien species Pollution Overexploitation Disease

(Wilcove et al. 1998 BioScience 48:607-615) Naiveity?? (Berger et al. 2001. Science 291:1036-1039) Climate Change

Has Extinction Slowed Diversification?

Overall increase of familial diversity despite extinctions

Loss ofDinosMostly

Marine

Shallows

(Myers 1997)

Modeling study suggests that tree of life can be vigorously pruned and still maintain diversity

Nee and May (1997)– What fraction of evolutionary history in a taxon

is left when some proportion of species are lost?

– Losing 80% of the species still preserved 50% of evolutionary history (measured as branches in phylogenetic tree)

– Doesn’t matter if we chose species at random or optimally based on genetic history

But, Importance of Species Loss To Rest of Ecosystem Depends on its Role Many species perform critical ecosystem services

(keystones in that regard)– soil generation, pest control, regulation of weather

and climate, nutrient cycling, seed dispersal, etc, etc (Daily et al. 1997).

So extinctions may have snowball effects Remember that the reason we can document

extinctions from the past is in large part because of the loss of dinosaurs in Late Cretaceous!

Does it Matter?

Hell Yes– Much is unknown, so save the parts

• (Aldo Leopold once said the first sign of an intelligent tinkerer is to save all the parts)

– Biodiversity is connected to ecosystem function• Loreau 2000. Oikos 91:3-17

– How many rivets can we pop?• Ehrlich and Ehrlich 1983. Extinction: the causes and

consequences of the disappearance of species. New York: Ballatine Books

So, What Do We Do?

Use Scientific Method to Identify Threat

Determine Spatial Extent of Protection--Gap Analysis

REMOVE THREAT

Release Probeto Test if Threat

is Removed

Captive Breeding

MonitorRecovery

Restock

Managein situ

Set up Reserves

?

Recommendations to Save Birds in the Americas

Secure sites 241 Locate new sites 214 Estimate population size in sites 197 Study ecology 164 Manage sites 91 Control taking 49 Educate people 23 Captive management 23 Taxonomic study 8 Other 14Bibby 1994 Proc Roy Soc Lond 344:35-40

Example--Lord Howe Island Woodhen Down to 20 individuals, confined to two mountain tops Did experiments to determine impacts of

– food availability

– rat predation

– pig predation

Remove Pigs Captive Breed, reintroduce, local stock Population up to 160 and stable Now should do reserve planning to manage entire island

References Rabinowitz, D. 1981. Seven forms of rarity. In The biological

aspects of rare plant conservation. H. Synge (Ed.), Wiley & Sons, Chichester. UK.

Gilpin, ME and ME Soule. 1986. Minimum viable populations: processes of species extinction. Pp 19-34. In. ME Soule (ed.) Conservation Biology. Sinauer, Sunderland, MA.

Pister, EP. 1993. Species in a bucket. Natural History January:14-19.

Diamond, J. M. 1989. The present, past and future of human-caused extinction. Philos. Trans. R. Soc. London B 325:469-478

References

Myers, N. 1997. Mass extinction and evolution. Science 278:597-598.

Schopf, TJM 1974. Permo-Triassic extinctions: relation to sea-floor spreading. J. Geology 82:129-143.

Daily, GC. Et al. 1997. Ecosystem services: benefits supplied to human societies by natural ecosystems. Issues in Ecology #2

Wilson, EO. 1992. The diversity of life. Belknap Press, Cambridge Ma.

Grant, PR. 1995. Commemorating extinctions. Am. Scientist 83:420-422.

References

Meffe, GK and CR Carroll. 1994. Principles of conservation biology. Sinauer, Sunderland, MA

Hughes, JB, GC Daily, and PR Ehrlich. 1997. Population diversity: its extent and extinction. Science 278:689-691.

Dobson, AP. Et al. 1997. Geographic distribution of endangered species in the United States. Science 275:550-553.

Czech, B. and Krausman, PR. 1997. Distribution and causation of species endangerment in the United States. Science 277:1116.

References

Baillie, J. and B. Groombridge. (eds). 1996 IUCN Red list of threatened animals. IUCN, Gland, Switzerland and Cambridge, UK. 448 p.

Spiller, D. A., J. B. Losos, and T. W. Schoener. 1998. Impact of a catastrophic hurricane on island populations. Science 281:695-697.

Nott, et al. 1995. Current Biology 5:14-17 Pimm, SL, Russell, GJ, Gittleman, JL and TM Brooks.

1995. The future of biodiversity. Science 269:347-350. Chapin, FS III, et al. 2000. Consequences of changing

biodiversity. Nature. 305:234-242.