8.2 Flashcards
define population
a breeding group of individuals of the same species occupying a particular habit and a particular niche
define gene pool
the sum total of all the genes in a population at a given time
what is the hardy-Weinberg equilibrium
the mathematical relationship between the frequencies of alleles and genotypes in a population
what is gene flow
the migration of either whole organisms or genetic material into or out of a population making different populations more alike but changing allele frequency in each population
what is allele frequency
number of individuals carrying a certain allele in a population
what is the equation for allele frequency
p + q = 1
what is the equation for genotype
p^2 + 2pq + q^2 = 1
what are the conditions of the Hardy-Weinberg equation
- there are no mutations
- there is random mating
- the population is large
- the population is isolated
- there is no selection pressure
what is a population bottleneck
the effect of an event or series of events that dramatically reduces the size of a population, causes a severe decrease in the gene pool of the population, resulting in large changes in allele frequencies and a reduction in genetic diversity
what is the founder effect
the loos of genetic variation that occurs when a small number of individuals become isolated forming a new population with allele frequencies not representative of the original population
what is stabilising selection
the natural selection acting to conserve what is already present in a population, reducing variety in a population so that the frequency of some alleles is very high but other alleles are greatly reduced
what is directional selection
the ‘classic’ natural selection that occurs whenever environmental pressure is applied to a population, showing change from one phenotypic property to a new one more advantageous in the circumstances
what is disruptive/diversifying selection
gives an increase in the diversity of the population rather than a trend in one particular direction, common when conditions are diverse and small subpopulations evolve different phenotypes suited to their very particular surroundings and often result in the evolution of a new species
what is genetic drift
random changes in the gene pool of a population that occur by chance not because they confer any advantage or disadvantage
