Conservation of Populations. Defining Populations Demographics – growth and decline Conservation genetics & populations. I. Defining populations. Spatial disjunction Distribution pattern, groups are separated by location, regardless of other similarities Genetic disjunction
Population Density – number of individuals per unit area or volume
Clumped pattern – individuals aggregated in patches
Uniform pattern – evenly spaced resulting from direct interactions
Random pattern – occurs in the absence of strong attractions or repulsions among individuals
Natality (avg. per capita birth rate)
Mortality (avg. per capita death rate)
Density dependent fecundity in fingernail clams, Musculium securis
conflicting demands. When an organism engages in one
activity other activities are constrained!
increases if birth rate > death rate
# of breeding individuals
Census Population Size (Nc) – actual number of individuals in a population
the rate at which new (neutral) mutants are fixed is 1/u ; this rate is INDEPENDENT of population size, N.
Due to the fixation of certain alleles, heterozygosity will decline in the case of genetic drift in small populations.
Ht = HO [1 – 1/(2N)]t
Normal lion sperm Abnormal lion sperm from an isolated, inbred population in Tanzania
Inbreeding leads to the expression of recessive deleterious alleles that are suppressed in heterozygotes
Case studies isolated, inbred population in Tanzania
Due to severe over hunting, by 1892 somewhere between 8 and 20 were left. Since then there has been an almost exponential increase, especially in the northern colonies. In 1957 there were 13,000 elephant seals, in 1976: 48,000. The population is still not at equilibrium (Boveng et al, 1988). In 1991, the total population was estimated at 127,000, with 28,164 pups born that year and there appears to be a 6% annual increase (Stewart et al, 1994)
Marsh rat isolated, inbred population in Tanzania
Silver rice rat
- depression symptomsCapra ibex ibex (Austria), C. i. aegagrus (Turkey) & C. i. nubiana(Sinai)