Mechanisms Of Evolution Flashcards
What is Hardy-Weinberg equilibrium? What are the conditions?
where allele/genotype frequencies don’t change
no mutations, no natural selection, population is infinite in size (no genetic drift), isolated from other populations (no gene flow), no sexual selection
What processes drive evolution?
natural selection, gene flow, genetic drift, mutation
What is gene flow?
happens when individuals leave a population, join another, and breed
transfer of alleles through immigration and emigration
What is genetic drift?
causes allele frequency to change randomly
any change in allele frequencies in a population due to chance
How can continual gene flow between 2 populations result in?
them becoming genetically similar, reduces genetic differences
What are the good and bad impacts of gene flow?
good: gene flow can increase genetic variation in the recipient population
bad: can slow adaption to local conditions
Why can gene flow slow adaption to local conditions?
Because it happens randomly with regards to fitness
Will gene flow increase or decrease fitness?
Depends on the situation
Where is genetic drift especially prevalent? Why?
Small populations
Easier for small populations to loss an allele or have an allele become fixed due to genetic drift
What are the two major ways genetic drift is seen?
Population bottleneck, founder effect
What is population bottleneck? What is it usually caused by?
A sudden reduction in population size
Disease outbreaks, natural catastrophes
What is the founder effect? What is it caused by?
Small group of individuals established a new population in a new area
Dispersal
Do allele frequencies usually change after genetic drift?
Yes if the population is small enough
How does increasing population size affect genetic drift?
The effects of genetic drift are minimized with increasing population size
Does genetic drift increase of decrease fitness?
Not predictable because genetic drift is random
What are the types of assortative mating?
Positive assortative mating and negative assortative mating
What is positive assortative mating?
Individuals choose mates with similar phenotypes more often than expected by chance
What is negative assortative mating?
Individuals choose mates with dissimilar phenotypes more often than expected by chance
How can we distinguish between sexes?
Male: produce smaller and less costly gametes (sperm, pollen…)
Female: produce larger and more energetically costly gametes (eggs)
What are secondary sexual characteristics?
Differences between sexes in traits that are not directly related to production of gametes
What is sexual selection?
The theory of selection in context in mating
What is sexual dimorphism?
Secondary sexual characters such as ornaments/weapons arising from female choice selection pressure
What is intersection selection?
Members of one sex choose mates based on some anatomical or behavioral trait of the other sex
Opposite sex
What are examples of intersexual selection?
Ornamentation, songs, pheromones
What is intrasexual selection?
Competition among members of the same sex for mates
What are examples of intrasexual selection?
Weaponry, sperm competition
What are some reasons females want attractive mates?
Competitive males often have the best territories, body size and other competitive characteristics will be inherited by females offspring
What is the handicap hypothesis?
Male that can support a costly and unwieldy ornament is likely to have an overall high genetic quality
What is the sexy son hypothesis?
Female receives indirect genetic benefits through her sons, who will be attractive to females and produce a lot of grandchildren
What type of natural selection does sexual selection drive?
Directional selection in traits in one or boy sexes
What are the effects of inbreeding on genotype frequency?
More homozygotes and less heterozygotes
