evolution of species Flashcards
e.g. species, mutations, variation, natural selection, selective advantage, adaptions, speciation
a species is
a group of organisms that can interbreed to produce fertile offspring
mutations are
random, spontaneous changes in genetic material and the only source of new alleles
rates of mutation can be increased by environmental factors such as
certain types of radiation and some chemicals
mutations that have little effect on the organism are
neutral
mutations that give the organism a disadvantage and decrease its survival chances are
harmful
mutations that give the organism an advantage and increase its chances of survival are
beneficial
new alleles produced by mutation can result in
plants and animals becoming better adapted to their environments
variation within a population of living organisms makes it possible for
a population to evolve over time in response to changing environmental conditions
species often produce
more offspring than the environment can support
the intensity of a selective factor such as predation is called
selection pressure
natural selection/survival of the fittest occurs when
there are selection pressures
an adaption is
an inherited feature of an organism that makes it well suited to survive in its habitat
the best-adapted individuals in a population have a
selective advantage
individuals with a selective advantage…
survive to reproduce, passing on the favourable alleles that confer the selective advantage to their offspring
the favourable alleles
increase in frequency within the population
speciation is
the evolution of 2 or more species from 1 original ancestor species
speciation occurs after
part of a population becomes isolated by an isolation barrier
isolation barriers can be
geographical, ecological or behavioural
different mutations occur in
each sub-population after speciation
natural selection selects for
different mutations in each sub-population due to different selection pressures
each sub-population evolves until…
they become so genetically different that they are 2 different species and can no longer interbreed to produce fertile offspring
an isolation barrier is
a barrier that prevents interbreeding and gene exchange between sub-populations of a species
natural selection is
the process which ensures the best adapted individuals survive