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4 Cards in this Set
- Front
- Back
What are the 4 indirect sources of variation?
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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 |
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what are the 3 direct sources of variation?
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duplication - error in meiosis
regulation - switch genes on or off recombination, segregation, independent assortment |
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what are the 4 pre-zygotic isolating mechanisms?
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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 |
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what are the 5 post-zygotic isolating mechanisms?
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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 |