Transcript Relating Foraging Behavior to Wildlife Management

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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 Range
General
Habitat
Requirements
General
Habitat
Requirements
Specific
Habitat
Requirements
Local
Brown Red
Populations Rat,
Mangrove
Somewhere
Starling
Large
Local
Peregrine Osprey
Populations Falcon
everywhere
small
Specific
Habitat
Requirements
Pygmy Silver
Cypress Sword
Alala
Alpine
Lily
Giant
Panda
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
 Census population was
0.6
Heterozygositiy (all
populations)
n = 16 flies
0.5
Theory, N = 16
 In theory, given ideal
0.4
conditions, we would
0.3
expect decline in
0.2 Theory,
heterozygosity to
N=9
0.1
follow solid lines.
Data
0
 Data fits line with
0
10
20
ideal population of n =
Generation (t)
9, thus the Ne = 9, not
H=2pq(1-1/2N)t, under ideal
16
conditions (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?
Shallows
Mostly
Marine
Loss of
Dinos
(Myers 1997)
 Five major mass extinctions through geologic time
– Late Permian--formation of Pangea, loss of shallows,
many marine organism extinctions (Schopf 1974)
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
Recent Occupancy
Many Recent
Extinctions
Few Recent
Extinctions, Long
Occupancy byHumans
Colors indicate when significant extinction events
occurred. Numbers indicate % of fauna that has gone
extinct in last 100,000 years (Burney 1993)
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).
Global Change and Biodiversity
Continental extinction
rates have increased
from 10-7 to 10-4
species/species/year
Nott, et al. 1995. Current
Biology 5:14-17
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 & beeeaters, 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 Earth
5% 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
“At
Risk”
Species at Risk
Endemic Species
Plant diversity, endemism, and rarity
5-4a,b,c
Source: Precious Heritage (2000) © TNC, NatureServe
Vertebrate diversity, endemism, and rarity
5-6a,b,c
Source: Precious Heritage (2000) © TNC, NatureServe
Distribution of Federally Listed Species
6-1
Source: Precious Heritage (2000) © TNC, NatureServe
County Distribution of Federally Listed Species
6-2
Source: Precious Heritage (2000) © TNC, NatureServe
Distribution of Imperiled Species by Ecoregion
Number of
Species
Number of
Endemic Imperiled Species
1-20
1-10
21-50
11-50
51-150
51-150
> 150
> 100
6-5
Source: Precious Heritage (2000) © TNC, NatureServe
What Reasons are Listed For
Endangerment in US? (Czech and Krausman 1997)
Cause
# Endangered
Interactions with nonnatives
Urbanization
Agriculture
Outdoor recreation, tourism
Ranching
Water diversions
Modified fire regimes,
silviculture
Pollution of water, air, soil
Energy exploration
305
275
224
186
182
161
144
Industry and military
131
144
140
What Reasons are Listed For
Endangerment in US? (Czech and Krausman 1997)
Cause
Harvest, intentional and
incidental
Logging
Roading
Genetic problems (inbreeding,
etc)
Wetland destruction
Plant succession
Disease
Vandalism (destroy, but no
harvest)
# Endangered
120
109
94
92
77
77
19
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?
Shallows
Mostly
Marine
Loss of
Dinos
(Myers 1997)
 Overall increase of familial diversity despite
extinctions
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
?
Set up
Reserves
REMOVE THREAT
Release Probe
to Test if Threat
is Removed
Captive
Breeding
Restock
Manage
in situ
Monitor
Recovery
Recommendations to Save Birds in the
Americas
 Secure sites
 Locate new sites
 Estimate population size in sites
 Study ecology
 Manage sites
 Control taking
 Educate people
 Captive management
 Taxonomic study
 Other
Bibby 1994 Proc Roy Soc Lond 344:35-40
241
214
197
164
91
49
23
23
8
14
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 275:550553.
 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.