Part 2 Flashcards
DNA & mating
Variation is heritable
Giraffe long neck/short neck
Variation exists amongst individuals in a population
short neck can’t reach high trees & can starve
Survival & reproduction success is variable
Long neck can reach trees & eat more
Non random survival & reproduction
No evolutionary change
Assumptions
Random mating
mating by chance
No natural selection
all members contribute to number of gametes in a pool
No genetic drift
no changing of frequencies
No gene flow
all alleles from original populations gene pool
No mutation
no alleles
NOT an evolutionary process, but CAN change phenotype frequencies
Random mating
Inbreeding
Non-random mating
Assortative mating
non-random mating
Mating between close relatives
inbreeding
Preferential mating between those with some genotype + phenotype
Assortative mating
Individuals of different species are prevented from mating
Pre-zygotic isolation
Individuals from different populations DO MATE, but hybrid have low fitness and don’t survive or reproduce
Post-zygotic isolation
Biologist use 3 approaches?
- Biological species concept
- Morphological species concept
- phylogenetic species concept
Populations reproductively isolated from each other
Biological species concept
Populations that are constantly morphologically distant from each other
Morphological species concept
Based on evolutionary history of populations
Phylogenetic species concept
Gene pool isolation due to geographical isolation
Allopatric Speciation
Organisms colonize new habitat —> new populations
Dispersal
Physical barrier splits population into subgroups
Vicarience
Barrier to gene floe isolates populations
Genetic isolation
Mutation, selection, and genetic drift in isolated populations cause divergence
Genetic divergence
- Gene pool isolation
- evolutionary changes
- reproductive isolation
speciation simplified
Genetic isolation via assortative mating (gene flow stops bc of this)
Sympatric speciation
Changes in chromosomes number confer reproductive isolation (gene flow stops bc change in chromosome numbers)
Polyploid speciation
results in hybrid offspring inhibiting a new environment
Hybrid speciation
