Topic 5: Ecological Genes Flashcards
What is an adaptation?
An adaptation is any heritable behavioural, morphological, or physiological trait that has evolved over a period of time by the process natural selection.
What is phenotypic plasticity?
An organisms with a specific genotype can change its phenotype based on environmental interactions. The organism can basically change what gene is expressed so the phenotype changes, but the genotype remains constant.
What is an example of phenotypic plasticity?
the Chinook king salmon, and the pitfall trap plant. In the spring the plant produces just regular photosynthetic leaves bc bugs are not yet active (still too cold for them). However at 25c the plant starts producing the pitfall traps as it is now warmer and the bugs are more active. the pits is still leaf but a highly modified one.
What is meant by directional selection?
the mean (middle/average) value of a trait is shifted towards one extreme over another.
What is meant by stabilizing selection?
selection which favours the mean at the expense of the extremes.
What is meant by divergent selection?
natural selection which favours BOTH extremes, leads to a misdial distribution of a characteristic.
What is an example of stabilizing selection?
baby birth weight. a baby that is too heavy/big when it is born is too difficult to birth and cause both the mom and baby to die. consequently, a baby that is too small may be too weak or fragile to survive. so we want a mean value of weight for the best possible chance of survival
How can divergent population happen?
typically happens when a population is subjected to multiple selection pressures. can lead to the formation of a new species.
How does genetic drift occur? where do we often see genetic drift?
genetic drift occurs within small populations due to randomness of sexual reproduction. often seen in new colonization and following a population crash.
What are the consequences of genetic drift?
reduced genetic diversity (extinction risk).
What is gene flow?
migration carries genes from one sub population to another. individuals must successfully reproduce to transfer genes.
What is gene flow good for?
Powerful force in reducing genetic DIFFERENCES between populations. This is not reducing genetic variation, but basically allowing different subpopulations to not diverge to far from one another.
What is a cline?
A cline is a measurable, gradual change over a geographic region in the average of some phenotypic character.
What are geographic isolates?
Geographic isolates are populations with extrinsic barriers that prevent the flow of genes with other sub populations.
What is the modern species concept?
A species is a group of populations whose individuals have the potential to interbreed and produce fertile offspring.
