9: Extinction and Genetics Flashcards
Primary risk factors to species going extinct
- Narrow geographic range
- Only a few populations (no rescue)
- Small population size (loss of variation)
- Hunted species
What is genotype
Genetic make-up of an individual
Genes/alleles present in individuals
What is phenotype
Physical appearance
Observable or measurable trait
Genetics + environment
Factors that detract from genetic variation
Inbreeding, selection, genetic drift
What is genetic drift
Certain allele/genotype might die off, leading to change in the offspring genotype freq
What provides a good estimate of loss of genetic variation
Effective population size (Ne)
What is inbreeding depression
Breeding among close relatives that leads to deleterious effects
Increase in homozygosity (inbreeding) can lead to… How do some wild species deal with this?
Increased mortality, decreased fecundity
May be avoidance mechanisms in the wild (e.g. male leaves); small pops can’t do this
Three types of species concepts
- Morphological species concept
- Ecological species concept
- Phylogenetic species concept
Factors that contribute to genetic variation
Mutation, recombination, gene flow, sex
Pros of sex
More variability within offspring; overcome deleterious (recessive) alleles
Overcome disease and parasites
Source of new types
Cons of sex
Half the rate of reproduction
Need to find a mate
STD’s
Why do cheating cheetah’s prosper
Female cheetah’s can store sperm
If she mates with multiple males, variability among cubs is high and they won’t all be susceptible to new pathogen
When does genetic diversity matter more? E.g.
In challenging environments
e.g. only heterozygous fur seals will survive to adulthood when krill levels are low
Name three of the ten predictions about genetic diversity (slide 30)
- genetic variation within species should be related to population size
- genetic variation within species should be related to island size
- island populations should have less genetic variation than mainland populations
