what is genetic diversity?
the number of different alleles in a population
how does natural selection work?
- random mutation results in new alleles
- new selection pressure favours animal with these advantageous alleles
- these survive and reproduce, pass on advantageous alleles to offspring
- new allele increases in frequency
- increase gene pool
describe directional selection
changed selection pressure, so distinct advantageous allele. curve moves to the right or left, and could become new species
describe stabilising selection
selection pressure favours intermediate phenotype, so graph becomes longer and thinner
describe disruptive selection
groups from an original singular original population are exposed to different selection pressures, as different alleles are advantageous
what is true of all types of selection?
always reduction in genetic variation
always in response to selection pressure
what defines a species?
when two organisms in that species can produce fertile offspring
why is courtship necessary?
- ensure the animals are the right gender
- right species
- both sexually mature and fertile
what is a phylogenetic classification system/
arranges species into groups based on their evolutionary origins and relationships. these groups do not overlap
order of the hierarchy
domain kingdom phylum class order family genus species
what is a species’ name made up of?
its genus and species
how can genetic diversity be compared?
- frequency of measurable or observable characteristics
- base sequence of DNA
- base sequence of mRNA
- amino acid sequence of proteins encoded by DNA and mRNA
