BRAINCAKEDesert Pupfish
Desert pupfish are small fish of the genus Cyprinodon that live in isolated springs, streams and pools in the deserts of south-western USA and northern Mexico. They are a well-known example of allopatric speciation.
During the last ice age, the Death Valley region of California and Nevada was much wetter. Large lakes and rivers connected the area, and a single ancestral pupfish population lived throughout it.
As the climate warmed and became drier over roughly the last 10,000 years, the lakes shrank and dried up. The pupfish population was split into many small groups, each trapped in a separate spring or pool surrounded by desert. The desert was a geographical barrier, so there was no gene flow between the groups.
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Key terms in this lesson
- allopatric speciation
- The formation of a new species when populations are separated by a geographical barrier, so gene flow between them stops.
- genetic drift
- A change in allele frequency in a population due to chance, which has a greater effect in small populations.
More in Natural Selection
- Speciation
- Types of Isolation
- Allopatric Speciation
- Endemic Species
- Adaptive Radiation
- Sympatric Speciation
- Howea Palm Tree
- Fruit Fly Rhagoletis pomonella
All 29 lessons in Natural Selection · All Edexcel AS-level Biology topics