2.6 - variation + evolution Flashcards
what factors produce variation between individuals
- genetic
- environmental
name the types of variation
- continuous + discontinuous
- heritable + non-heritable
what’s discontinuous variation
- type of variation that can be categorised, e.g: blood group
- characteristic can only appearing discrete values
- influenced by one or two genes + environmental factors have little effect on
what’s continuous variation
- type of variation that can’t be categorised, e.g: height
- produces continuous range in which a characteristic can take any value
- influenced by multiple genes + is often significantly affected by environmental factors
compare heritable + non-heritable variation
heritable - genetic differences between individuals
non-heritable - acquired differences in phenotypes of individuals that can’t be inherited
what’s evolution
- change in allele frequencies in gene pool of population over time
- occurs due to natural selection
how does natural selection cause change in allele frequencies over generations
organisms w/ advantageous characteristics are more likely to survive + pass their favourable alleles to offspring
frequency of unfavourable alleles decreases
what are selection pressures
- environmental factors that drive evolution by natural selection + limit population sizes
- can change frequency of alleles in population
give examples of selection pressures
- predation
- disease
- competition (for food, habitats, mates)
- environmental conditions, e.g: temperatures
how can allele frequencies be expressed
as percentage or proportion of total number of all alleles for that gene
state the 2 types of competition
- interspecific
- intraspecific
what’s interspecific competition
type of condition that takes place between members of different species
what’s intraspecific competition
type of competition that takes place between members of same species
define gene pool
all of the diff versions of genes (alleles) in individuals that make up a population
what’s genetic drift
variations in allele frequencies in small populations due to chance (rather than as a result of selection pressures)