Variation and evolution Flashcards
What is heritable variation
A characteristic that can be passed onto future generations, eg. hair colour
What is non-heritable variation
A characteristic that cannot be passed on to future generations, eg, obesity
What is continuous variation
Controlled by multiple genes and provides a range of potential phenotypes, eg. height
What is discontinuous variation
Controlled by one gene and provides determined categories of potential phenotypes
What is a ecological niche
the role, activities, and location of an organism in a habitat
What is the competitive exclusion principle
no two organisms can occupy exactly the same niche or else competition occurs
Give examples of selection pressures
Food Supply Nesting sites climate pollution Habitat destruction
Define a gene pool
the total of all the alleles present in a particular population at a certain time
Define genetic drift
the chance increase or decrease in allele frequencies over time
What size population does genetic drift affect most
A small population as there is a greater chance of alleles being lost
What is the founder effect
the loss of genetic variation in a new population by a very small number of individuals from a larger population
Describe stabilizing selection
Selects against the extremes of a phenotype
Describe directional selection
Selects against one extreme in favour of another
Describe disruptional selection
Selects against the median in favour of the extremes of a phenotype
What is allopatric speciation
Speciation due to a geological barrier causing isolation, eg. urbanisation, volcanic eruption etc…
