speciation and artificial selection Flashcards
define artificial selection
selection of plants or animals with desirable characteristics for breeding - aka selective breeding
what creates selection pressure in natural selection
nature
what creates selection pressure in artificial selection
humans breeding the organisms
describe selection
choosing 2 of the same species which show desirable traits
- eg. milk yield
describe interbreeding
choosing the organisms that show the best/desirable traits and breeding them together
what is speciation
formation of a new species through evolution
state the 5 steps of artificial selection
- selection
- interbreed
- inbreed
- repeat
- change in frequency
describe some of the problems caused by inbreeding (3)
- limiting gene pool and genetic diversity reduces the ability of inbred organisms to adapt to environmental change
- closely related organisms are likely to have same recessive alleles so offspring are more likely to be homozygous for recessive traits for genetic disorders
- reduces ability to survive and reproduce so are less biologically fit
what is allopatric speciation
when some individuals are separated from the rest of a population by physical barriers
- eg. sea, desert, mountain range
why are there different physical adaptations for organisms in allopatric speciation
- environments are different
- so selection pressures different
- so physical adaptations different
what is sympatric speciation
when members of two different species interbreed and form fertile offspring - new hybrid is formed
what do prezygotic reproductive barriers do
prevent fertilisation and zygote formation
what do postzygotic reproductive barriers do
reduce viability of reproductive offspring potential
what is a gene bank
stores biological samples
- eg. sperm and eggs or seeds
what is outbreeding
breeding unrelated or distantly related varieties
define isolating mechanisms
ways in which organisms become isolated from each other with no gene flow, in order to form new species
define isolation
separation of members of a species so there is no gene flow
why can an isolated species no longer produce fertile offspring?
- as phenotypes have been changing, DNA has been changing
- new alleles/genes/chromosomes
- cannot produce viable gametes through meiosis
define total reproductive isolation
reproducing isolated species together but they will no produce fertile offspring
define temporal isolating mechanism
define ecological isolating mechanism
define behavioural isolating mechanism
define mechanical isolating mechanism
define genetic drift
changes in allele frequency within a population between generations
