Transcript Population Dynamics

Population Dynamics
Goal of these two weeks:
Predicting the Probability of Extinction
Reproduction and Life History Tables
Information Needed
Longevity
Sex Ratio
Age of sexual maturity
Number of reproductive events
per year
Number of offspring per event
Causes of mortality
Survivorship
Calculation of Age Specific Fertility
Understanding Mortality
• Density Dependent
– Food
– Water
• Density Independent
– Age
– Road Mortality
• Problematic
– Predation
– Disease
Density Dependent Population Change
Why do populations fluctuate?
Geometric and Exponential Growth
Including Density Independent Mortality
r and K Selection
Importance to Conservation Planning
Persistence and Population Dynamics
Florida panther
Population Dynamics and Vulnerability to Extinction
Fresno kangaroo rat
Listing Status: Endangered
In the wild, the breeding season of the San
Joaquin kangaroo rat typically runs from
December to August, but this species is also
known to breed throughout the year (2) (3).
The gestation period lasts only 32 days, and
the young are born in the underground burrow
(1) (5) (8). There are usually up to 3 offspring
per litter, and the young are relatively well
developed at birth, weighing about 4 grams
and opening their eyes at 10 to 11 days old (3)
(8). The young San Joaquin kangaroo rats first
leave the burrow at about 14 to 18 days old
and are weaned at 21 to 24 days, attaining
adult weight after about 2.5 to 3 months (3).
The San Joaquin kangaroo rat reaches sexual
maturity as early as 82 days old (5), and
females may potentially give birth to up to
three litters a year
Boom and Bust Cycles – Recovery and Disaster
Fragmentation and loss of habitat are the
primary causes for the decline and continued
threat to the survival of Buena Vista Lake
shrews. The historical Buena Vista Lake is now
drained and cultivated and Kern Lake has been
reduced to 33 acres with a small pond that is
artificially maintained and contains a more
xeric (drier) plant community. Kern Lake
Preserve is privately owned and a
Conservation Agreement to protect the only
known population of this species has not been
negotiated. Because of the smallness and
isolation of the population, the Buena Vista
Lake shrew also faces high risks of extinction
from genetic and environmental factors
Area dependence and patch geometry
Quantifying the Metapopulation Model
• Pe and Pc
• Levins Model
• SPOM