Imperiled Populations I

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Imperiled Populations I
8 Sept 2009
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Papua New Guineas Lost World- Mount Bosavi -
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Papua New Guineas Lost World- Mount Bosavi -
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Papua New Guineas Lost World- Mount Bosavi -
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Papua New Guineas Lost World- Mount Bosavi -
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Papua New Guineas Lost World- Mount Bosavi -
Bosavi wooly rat 32 long, 3.3 lbs (click for
video)
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Does the Bosavi wooly rat have a bright future?
Should conservationists care?
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Characteristics of At-Risk Species- Rules that
usually apply (but not always) -

• Individuals have large home ranges.
• Large bodied species.
• May be offset by longer lifetimes or greater
  dispersal ability.
• Limited dispersal capability.
• Low genetic diversity.
• Specialized habitat requirements.
• Tendency to aggregate.
• Naïve to humans.

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The Florida Panther has run out of real estate in
the Everglades.
Male home ranges are 90,000 acres. Female home
ranges are 44,000 acres.
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Characteristics of At-Risk Species- Rules that
usually apply (but not always) -

• Individuals have large home ranges.
• Large bodied species.
• May be offset by longer lifetimes or greater
  dispersal ability.
• Limited dispersal capability.
• Low genetic diversity.
• Specialized habitat requirements.
• Tendency to aggregate.
• Naïve to humans.

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Too big for their own good?
Hummer H3 5,000 lbs.
African Elephant 8,000-15,000 lbs. 22 month
gestation 1 calf per birth event 4-9 yr. breeding
interval consume gt200 lbs./day live 50-70 yrs.
Blue Whale gt300,000 lbs. (newborn wt. 5,000
lbs.) 11 month gestation 1 calf per birth
event 2-3 yr. breeding interval consume 5
tons/day live 60-80 yrs.
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Characteristics of At-Risk Species- Rules that
usually apply (but not always) -

• Individuals have large home ranges.
• Large bodied species.
• May be offset by longer lifetimes or greater
  dispersal ability.
• Limited dispersal capability.
• Low genetic diversity.
• Specialized habitat requirements.
• Tendency to aggregate.
• Naïve to humans.

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The Devils Hole Pupfish. . . as endangered as
they come.
(click)
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Characteristics of At-Risk Species- Rules that
usually apply (but not always) -

• Individuals have large home ranges.
• Large bodied species.
• May be offset by longer lifetimes or greater
  dispersal ability.
• Limited dispersal capability.
• Low genetic diversity.
• Specialized habitat requirements.
• Tendency to aggregate.
• Naïve to humans.

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Like fish in a barrel. . .
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Characteristics of At-Risk Species- Rules that
usually apply (but not always) -

• Individuals have large home ranges.
• Large bodied species.
• May be offset by longer lifetimes or greater
  dispersal ability.
• Limited dispersal capability.
• Low genetic diversity.
• Specialized habitat requirements.
• Tendency to aggregate.
• Naïve to humans.

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Experience with humans. . . this ones a toss-up.
Bosavi wooly rat Vulnerable because its clueless.
Brown bear Vulnerable because its way too
comfortable around people.
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Characteristics of At-Risk Species- Rules that
ALWAYS apply -

• Narrowly distributed geographic ranges (high
  endemism).
• Limited to one or several populations.
• Small population size.

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How do we measure the size of a population?
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Estimating Population Size- Lincoln-Petersen
Mark-Recapture -
C1 C2
N
R
Where N total population size estimate (also
denoted NC). C1 of animals captured
marked in 1st sample. C2 of animals captured
in 2nd sample. R of 1st sample marks
recaptured in 2nd sample.
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Estimating Population Size- Simulated data
results -
140
120
100
80
60
40
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Mark-Recapture Assumptions

• Studying a closed population.
• no births
• no deaths
• no immigration
• no emigration
• Random mixing between 1st 2nd samples.
• Larger samples are always better.
• Take results with a grain of salt!

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Total population size (N)vs.Effective
population size (Ne)
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Effective Population Size (Ne)
males 36 females 40
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Effective Population Size (Ne)
4 Nm Nf
Ne
Nm Nf
Where Nm number of males. Nf numer of
females.
4 36 40
males 36 females 40
Ne
75
(36 40)
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Four studly, alpha males . . .
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Effective Population Size (Ne)
males 4 females 16
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Effective Population Size (Ne)
4 Nm Nf
Ne
Nm Nf
Where Nm number of males. Nf numer of
females.
4 4 16
males 4 females 16
Ne
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(4 16)
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Elephant Seals

• Male-dominated harems
• Males fight to establish alpha status.
• A single alpha male mates with many females.
• Ne is relatively low.

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Lake Trout

• A broadcast spawner (unlike most trout)
• Eggs milt (sperm) are secreted into the water
  column, then settle into rock substrate.
• All adults have a high probability of
  contributing genetic material to next generation.
• Ne is relatively high.

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Gray Wolf

• Packs dominated by alpha pairs.
• A single alpha male and alpha female establish
  dominance.
• Only alpha pair breeds.
• Ne is extremely low.

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Population Demographics- specific concerns -

• Survival patterns
• How long do individuals tend to live?
• Reproductive potential
• How many offspring can an individual produce?
• How is age distributed?
• Effects of dispersal habitat configuration
• Metapopulation dynamics.

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How Long do Individuals Live?- Survivorship
Curves -
Type I
Type II
Number of survivors
Type III
Age
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Population Demographics- specific concerns -

• Survival patterns
• How long do individuals tend to live?
• Reproductive potential
• How many offspring can an individual produce?
• How is age distributed?
• Effects of dispersal habitat configuration
• Metapopulation dynamics.

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Reproductive potential - at the low end -

• Killer whales have very low reproductive
  potential
• Sexual maturity at 15 years.
• Produce a single calf every 5 years.
• Remain sexually active until 40 years of age.
• Maximum lifetime output 5 calves.
• Infant mortality rate 50.

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Age Distributions
Stable population
Declining population
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Clarke County Age Distribution
United States Age Distribution
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Population Demographics- specific concerns -

• Survival patterns
• How long do individuals tend to live?
• Reproductive potential
• How many offspring can an individual produce?
• How is age distributed?
• Effects of dispersal habitat configuration
• Metapopulation dynamics.

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Demographic Stochasticity

• Random fluctuations in demographic parameters
  (birth death rate, immigration emigration
  rate, sex ratios, or age structure).
• Allee effects become increasingly problematic at
  small population sizes
• probability of encountering mates
• communal mating activity
• cooperative/group defense hunting success
• communal insulation nesting

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The Florida Everglades are the sole habitat of
the Florida Panther.

• Total area 2,600,000 acres
• Panther N 100 (up from 6)
• Panthers are solitary

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Sage grouse congregate in leks, to perform
courtship displays. If numbers are insufficient
to form leks, no breeding will occur.
(click)
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Wild African dogs hunt in social packs.
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Common Eider duck overwinters in Bering Sea.
Large aggregations needed to maintain body heat
and open water.
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Reading Assignments

• Read text p. 283-290, 293-306, 309-320.