Patterns of Evolution n n n Divergent evolution
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Patterns of Evolution: n n n Divergent evolution – the accumulation of differences between related groups Convergent evolution – the accumulation of similarities between unrelated groups Coevolution – the process by which 2 or more species evolve in response to changes in each other.
Divergent vs. Convergent Similar Characteristics
Coevolution
Are the following pairs examples of divergence or convergence: ___ C 1. ___ D 2. Platypus Duck (mammal) (bird) Both lay eggs C 4. ___ D 3. Venomous Snake Both Mammals Lives in Water Lives on Land Nonvenomous Snake Shark Dolphin (fish) (mammal) Both streamlined
SPECIATION: n n species – a group of organisms that are closely related and can naturally mate to produce fertile offspring speciation – the formation of new species as a result of evolution by natural selection; occurs when a species becomes so different they can no longer interbreed and are eventually considered to be different species
What leads to speciation (the formation of a new species)?
Reproductive Isolation leads to Speciation. v Reproductive Isolation – is the condition in which two populations of the same species can no longer breed with one another Ex: as two isolated populations of the same species become more different over time, they may eventually become unable to breed with one another; generally, when the individuals of two related populations can no longer breed with one another, the two populations are considered to be different species.
Factors that lead to Reproductive Isolation: n n n Geographical isolation – physical barriers such as rivers or mountains separate a population Temporal Isolation – timing prevents reproduction between a population Behavioral Isolation – differences on courtship or mating behaviors
Identify which type of reproductive isolation is being described below: →Geographical isolation →Temporal Isolation →Behavioral Isolation T 1. The Red-legged Frog breeding season lasts from ___ January to March. The closely related Yellow-legged Frog breeds from late March through May. ___ G 2. A mountain range prevents two types of goat from mating, causing the gene pool to become less varied. B 3. Female fireflies only flash back and attract males ___ who first signaled to them with a species-specific rhythm of light signals. G 4. A forest fire causes the permanent separation of a ___ group of deer from their native population, causing the small group to interbreed only with one another.