BIO 370 Chapter Notes - Chapter 17: Amphilophus Citrinellus, Apoyo Lagoon Natural Reserve, Sympatric Speciation
What is sympatric speciation?
No geographic boundary exists b/w diverging pops.
Speciation that occurs without complete isolation usually requires several special conditions.
A likely significant cause is disruptive selection coupled with assortative mating.
Disruptive selection – extreme values are favored over intermediate values of a trait.
Assortative Mating = Like mating with like.
The consequence is to decrease within-variation and increase between-variation (increases
homozygosity above HW equilibrium frequencies at both ends of the spectrum.)
Lake Apoyo in Nicaragua contains two species of cichlid fish, the Midas cichlid and the Arrow
cichlid. Midas is found in many lakes, but Arrow is only found in Lake Apoyo.
Lake Apoyo
has both species.
find more resources at oneclass.com
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Document Summary
Speciation that occurs without complete isolation usually requires several special conditions. A likely significant cause is disruptive selection coupled with assortative mating. Disruptive selection extreme values are favored over intermediate values of a trait. The consequence is to decrease within-variation and increase between-variation (increases homozygosity above hw equilibrium frequencies at both ends of the spectrum. ) Lake apoyo in nicaragua contains two species of cichlid fish, the midas cichlid and the arrow cichlid. Midas is found in many lakes, but arrow is only found in lake apoyo. Researchers hypothesized that species arrow arose sympatrically from an ancestral population of species midas. Among other types of research, they compared 840 base pairs of mitochondrial dna in hundreds of species midas and species arrow. Apoyo species midas and apoyo species arrow shared unique haplotypes, indicating a recent common ancestry exclusive of other midas populations.
