BALANCING SELECTION IN A DESERT STREAM-DWELLING FISH, POECILIOPSIS MONACHA

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Desert stream fish (Poeciliopsis monacha) face extreme environmental fluctuations.
• Understanding genetic adaptations to environmental stress is crucial for species survival.

Purpose of the Study:

• To investigate the association between genotypes at four gene loci and survival rates under acute environmental stress.
• To identify the role of genetic variation in Poeciliopsis monacha's adaptation to fluctuating desert conditions.

Main Methods:

• Examined four diallelic gene loci (Ldh-1, Idh-2, Pgd, Ck-A) in Poeciliopsis monacha.
• Assessed differential survival of individuals exposed to acute heat, hypoxic, and cold stress conditions.

Main Results:

• Common alleles at the studied loci correlated with higher survival during heat and hypoxic stress.
• Alternate alleles were associated with increased survival during cold stress.
• Heterozygotes generally showed intermediate survival and less variance compared to homozygotes.

Conclusions:

• The study identified balancing selection processes that maintain genetic polymorphism in Poeciliopsis monacha.
• Linkage disequilibrium suggests allozymes may serve as markers for underlying survival-modifying genes.