genetic diversity and adaptations Flashcards
(16 cards)
what is genetic diversity?
the number of different alleles of genes in a population
how can we tell organisms are of the same species by looking at genes?
identical genes but may have different combinations of alleles
what is a gene pool?
the sum of all alleles within an inter-breeding population at a particular time
what can increase a gene pool?
mutation, immigration (new individuals with new alleles have entered the population)
why is it true that the greater the genetic diversity, the more likely that some individuals in a population will survive an environmental change?
because there is a wider range of alleles and therefore a wider range of phenotypes
some individuals will have the phenotype which makes them more likely to survive this environmental change
when is genetic diversity reduced?
when a species has fewer different alleles, could be due to selective breeding
what is the factor that enables natural selection to occur?
genetic diversity
what does natural selection result in?
species that are better adapted to their environment, these adaptations may be anatomical, physiological or behavioural
what is meant by genetic drift?
alleles occurring at a certain frequency in the larger population will occur at a different frequency in a smaller subset of that population
what is meant by a population bottleneck?
when a population’s size is reduced for at least one generation
why can a population bottleneck reduce a population’s genetic variation by a lot?
because genetic drift acts more quickly to reduce genetic variation in small populations
what is a founder effect?
when a new colony is started by a few members of the original population.
this small population size means the colony may have:
-reduced genetic variation from the original population
-a non-random sample of the genes in the original population
what are the key words for describing the process of natural selection? (9)
-over populated
-variation
-mutation
-selection pressures
-most adapted, differential survival
-reproduction
-pass on alleles
-time
-change in allele frequency
what first starts the process of natural selection?
reproduction creates more individuals than can possibly survive (over populated)
there is variation within population
random mutations occur which creates new alleles and this increases variation in phenotypes
once variation in the population is established, how do we describe process of natural selection?
selection pressures applied- different factors affect chances of survival (predation, disease, competition for limited resources)
some phenotypes are more advantageous to survival than others, this is called differential survival
individuals that survive, reproduce
the surviving individuals reproduce during natural selection, then what happens?
the alleles for the advantageous phenotypes are passed on
over time/ many generations
so there is an increase in the frequency of the alleles for the advantageous phenotypes
