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4 Cards in this Set

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  • Back
What are the 4 indirect sources of variation?
ontogeny - age, growth and development
phenotypic plasticity - ability to chnage phenotype accoding to environment
heterochrony - evolutionary change in phenotype based on alteration in timing of developmental events
allometry- relative growth of part of an organism in relation the growth of the whole
what are the 3 direct sources of variation?
duplication - error in meiosis
regulation - switch genes on or off
recombination, segregation, independent assortment
what are the 4 pre-zygotic isolating mechanisms?
habitats - different selection pressures
seasonal/temporal - active at different times of day or in different seasons
behavioural - different behaviours
mechanical/physical - sex organs not compatible
what are the 5 post-zygotic isolating mechanisms?
gamete incompatability - sperm can't penetrate egg/survive in repro tract
zygote mortality - egg fertilised but zygote doesn't develop
hybrid inviability - zygote fails to divide
hybrid sterility - offspring can't reproduce
hybrid breakdown - repetitive breeding of hybrids leads to inviability