evolution revision

natural selection

process where individuals with advantageous traits survive/reproduce + environment decides who survives

species

a group of organisms that are capable of reproducing and producing fertile offspring

adaptation

a heritable trait that increases an organism’s chance of survival and reproduction in a particular environment

selection pressure

a factor, agent, or something that affects the survival of an individual in its environment

mutation

random changes in dna that introduce new traits → most are neutral/harmful, but some can be beneficial and become common

population

members of the same species living in the same location at a specific time

divergent

groups from the same ancestral species evolve and accumulate differences → eventually leading to the formation of distinct species

convergent

two species evolve to show similar characteristics or abilities

natural selection process

variation → populations have differences in traits.

selection pressures → struggle for survival (e.g. predators, disease, competition).

survival of the fittest → individuals with favourable traits survive & reproduce more.

inheritance of favourable traits over time → adaptations → increase overall survival of the population

artificial selection

humans decide which favourable traits are passed

speciation

the formation of new and distinct species

genetic diversity + importance

variety of genes within a population → important because it allows species to adapt to changing environments

recombination

involves the exchange of genetic material between chromosomes

variation

differences between members of a species

adaptation types

structural: physical body features (e.g. thick fur, cactus spines)

behavioural: actions or habits (e.g. birds migrating, nocturnal hunting)

physiological: internal body processes (e.g. snake venom, sweating, shivering)

variation differences

some differences are genetically determined and inherited from an organism’s parents

other differences are caused by the environment and are not passed onto the next generation

speciation key points

physical isolation of the population

• divided by a physical barrier and no longer able to interbreed

natural selection on each of the seperate populations cause each to change over many generations

• different population experience different selective pressures

reproductive isolation occurs when changes have accumulated enough so that individuals from the seperate population can no longer interbreed

• a new species has emerged

extinction

permanent loss of a species

homologous structures

similar physical features in organisms that share a common ancestor, but the features serve completely different functions

fossil

preserved remains/imprints of ancient organisms