Chapter 22: Evolution by Natural Selection
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What was unique about Darwin’s and Wallace’s biological theory of evolution?
They proposed that evolution occurs by natural selection which led to the beginning of population thinking
What is population thinking?
The idea where by variation among individuals is the key to understanding evolution
What evidence indicates there has been descent with modification from a single common ancestor?
The geographic proximity of closely related species, the existence of genetic developmental and structural homonologies and the formation of new species from pre-existing species
How can natural selection be explained using Darwin’s postulates?
Heritable variation leads to differentiable reproductive success
What are Darwin ‘s four postulates?
Variation exists about incliriduals, some trait differences are heritable, survival and reproductive success are highly variable and the individuals that sunvie the best and reproduce the most are not a random sample of the population
How are biological fitness and adaptation related?
Adaptions increase biological fitness which is the ability to produce viable and fertile offspring
What is biological fitness?
The ability of an individual to produce fertile, surviving offspiing relative to the ability in other individuals of the population
What is an adaptation?
A heritable trait that increases the fitness of an individual in a particular environment relative to individuals lacking that trait
What is acclimatization?
A change in an individual’s phenotype that occurs in response to change in natural environmental conditions
What is adaptation?
A heritable trait that increases the fitness of an individual relative to individuals lacking that trait
What is the difference between acclimatization and adaptation?
Changes due to acclimatization are not passed down to offspring
Is evolution ongoing now?
Yes
How is the statement that evolutionary change occurs in organisms false?
Because evolutionary change arises in populations, not individual organisms
How is the statement that evolution is goal directed false?
This is because adatiptions do not occur because organisms want or need them. They occur by chance, not on purpose
How is the statement that evolution perfects organisms false?
There are a few reasons. Some of them are that some traits aren’t always adaptive, some fitness trade-offs exist and some traits are genetically, historically and environmentally constrained