variation and selection

what is variation

differences between individual of the same species

continuous variation

a feature that can be measured and given value from a range of values e.g body length and body mass and is caused by both genes and the environment

discontinuous variation

a feature that can’t be measured but is one of a few distinct options e.g ABO blood type and is usually caused by genes only

what is a mutation

a change in the arrangement of bases in an individual gene or in the structure of the chromosome resulting in the formation of new alleles

what is an adaptive feature

an inherited feature that helps an organism to survive and reproduce in its environment

what is a xerophyte

a plant that has adaptive features that help it to survive in an environment where water is scarce

what is a hydrophyte

a plant that has adaptive features that help it to survive in water

species

organisms that can reproduce to produce fertile offspring

what is evolution

a gradual change of an organism over time

stages of natural selection

• each species reproduces and the offspring show variation

• there is lots of competition between these offspring

• the ones with the best adaptions for their environment survive, the others die

• these survivors pass on their better variations to their offspring

what is artificial selection

the selection by humans of individuals with desirable features to then cross breed to produce the next generation and then selecting the offspring showing the desirable features

what is adaption

the process, resulting from natural selection, by which populations become more suited to their environment over many generations

superbugs - antibiotic resistance

• evolution has occurred in bacteria over recent years to create superbugs

• these are bacteria that are resistant to the antibiotics that we use to treat people who are ill