b13- variation and evolution Flashcards
what is variation?
all the differences in the characteristics of individuals in a population
variation may be due to differences in:
-the genes they have inherited (e.g blood group)
-the conditions in which they have developed(environmental)
-a combination of genes and the environment (e.g height)
is there usually a massive amount of genetic variation within a population of a species?
yes
all of this genetic variation is due to?
mutations
what are mutations?
random changes to DNA
effect of mutations
-most have no effect on the phenotype
-some influence the phenotype
-very few determine the phenotype
mutations occur
continiously- very rarely a mutation will led to a new phenotype
if the genotype is suited to an environmental change, what can it lead to?
a relatively rapid change in the species
what does selective breeding involve?
-choosing parents with desired characteristics from a mixed population
-they are bred together
-from the offspring, those with the desired characteristics are bred together
-this continues over many generations until all offsprings show desired characteristics
what is evolution?
a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species
what does the theory of evolution by natural selection state?
that all species of living things have evolved from simple life forms that first developed more than three billion years ago
what does evolution occur through?
natural selection of variants that give rise to phenotypes best suited for their environments
give an example of evolution
-environment gets colder, rabbits with alleles for thicker fur are more likely to survive that rabbits with thinner fur
-those with thicker fur–>more likely to survive + reproduce
if two populations of one species become so different in phenotype what can happen?
they can no longer interbreed to produce fertile offspring- they have formed two new species
what is modern medical research exploring?
the possibility of genetic modification to overcome some inherited disorders.