Speciation

How species evolve

1) struggle for existence due to selective pressures (environment, competition, predators)

2) variations arise from mutations

3) greater fitness for certain genes

divergence

mechanism by which a single ancestral lineage becomes 2 separate groups w/ common ancestry

speciation (type of divergence)

when a new species is formed

Biological species concept

population/groups of populations whose members have the likely potential to interbreed & produce fertile offspring

limitation to BSC

only applies to sexually reproducing organisms like animals and fungi

morphological species concept

diff in structures/make up r measurable enough that don’t overlap w/ other groups and r considered separate species

ex with dogs and wolves

dogs and wolves r capable of interbreeding and producing fertile offspring. So under BSC, they COULD BE considered the same species. But under MSC they r diff. Due to kep aspects of their behavior they actually don’t breed when in contact

most common method for divergence to lead to speciation

must be separation of a single gene pool. There is Allopatric/geographic speciation and sympatric speciation

allopatric/geographic

physical barrier

sympatric speciation

change in genetic make-up NOT caused by change in climate/environment and physical barrier. Can be caused by disruptive selection

difference between Genetic drift and Gene flow

Genetic drift is when there is RANDOM change in genetic make-up of pop. Gene flow is when certain allele frequencies can change when new individuals arrive/leave and the changes r random/

trends in evolution

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adaptive radiation

when single/small # of lineages diverge into multiple new clades. This usually coincides with an ecological/geological event that generates many new selective pressures (new niches)

how does major trend in animal evolution, Multicellularity-complexity-growth/ sac like-tube like- larger body, relate to development

Develop of organism relies on differentiation & specialization of cells (which relies on diff SWITCHES and TF’s being activated in diff cells. Evolutionary, mechanisms that affect switches and TF (types of mutations) will affect develop, which leads to evolutionary chnages