28) Unit 2 - Drift and Selection Flashcards
define evolution
evolution is the change in the genetic composition of a population over successive generations
what process cause evolution
- Genetic drift
- Natural selection
- sexual selection
what is genetic drift
the RANDOM change in the frequency of a particular allele within a small population
why is genetic drift more important in small populations
because in small populations alleles are more likely to be lost from the gene pool
are natural and sexual selection random or non-random porcesses
non-random
what is natural and sexual selection
non random process where certain alleles occur more frequently within a population because they confer a selective advantage
These alleles increase chances of survival for that individual to live and pass on their advantageous allele to offspring
what is intrasexual selection
- Refers to selection withing the same sex
* Individuals (usually males) compete with each other with ritualized displays of strength
what is intersexual selection
refers to individual (usually femalees) choosing the opposite sex
what causes variation in traits/characteristics?
mutations
what do mutations give rise to?
New sequences of DNA/ novel alleles within a population
This results in new variations of traits
Mutations can be ________ or ______ but in rare cases they are beneficial to the _________ of the individual
Mutations can be HARMFUL or NEUTRAL but in rare cases they are beneficial to the FITNESS of the individual
name the 2 types of fitness
- absolute
* relative
describe absolute fitness
the ratio of frequencies of a particular genotype in one generation compared to the previous generation
describe relative fitness
the ratio of surviving offpring of one genotype to the next
How do alleles begin to come more frequent as generations go on?
- As organisms produce more offspring than the environment can support, they begin to compete for limited resources
- Individuals with favorable alleles are more likely to survive to breed
- Through inheritance these alleles become more frequent in further generations
