Genetic variation as a test of natural selection

Area of Science:

• Evolutionary Biology
• Genetics
• Herpetology

Background:

• Allozymic variation is a key indicator of genetic diversity within species.
• Bufo viridis (green toad) populations present a unique opportunity to study high levels of genetic variation.
• Understanding genetic variation is crucial for assessing population health and adaptive potential.

Purpose of the Study:

• To quantify the extent of allozymic variation across 12 populations of Bufo viridis in Israel and the Vis Adriatic Island.
• To investigate the relationship between genetic variation, population structure, and environmental heterogeneity.
• To explore the role of natural selection in shaping genetic diversity patterns.

Main Methods:

• Electrophoretic analysis of allozymic variation at 26 loci.
• Statistical analysis of heterozygosity per locus per individual (H).
• Assessment of differential gene frequencies and inbreeding coefficients (Fe) to infer selection pressures.

Main Results:

• Bufo viridis displays higher genetic variation than any vertebrate previously studied, with a mean heterozygosity (H) of 0.133.
• Heterozygosity was higher in central populations compared to isolates and varied across protein classes (highest in transferases/hydrolases, lowest in oxidoreductases/nonenzymatic proteins).
• Significant heterogeneity in inbreeding coefficients (Fe) across loci provided evidence for both uniform and diversifying natural selection.

Conclusions:

• The exceptionally high genetic heterozygosity in Bufo viridis is likely an adaptive strategy for survival in heterogeneous environments.
• Natural selection acts on gene frequencies, influencing the observed patterns of genetic variation.
• Conservation efforts should consider the genetic diversity and adaptive capacity of Bufo viridis populations.