Genetic polymorphism and evolution in parthenogenetic animals. I. Polyploid curculionidae

Area of Science:

• Evolutionary Biology
• Genetics
• Entomology

Background:

• Parthenogenetic organisms reproduce asexually, raising questions about their genetic diversity and evolutionary potential.
• Polyploidy is common in parthenogenetic weevils, but its origin and relationship with parthenogenesis remain debated.
• Understanding genetic variation in these populations is key to comprehending their evolutionary trajectories.

Purpose of the Study:

• To investigate the genetic variability within and between triploid and tetraploid parthenogenetic weevil populations.
• To compare the genetic structure of parthenogenetic weevils with their diploid bisexual relatives.
• To assess the evolutionary status and origin of parthenogenesis and polyploidy in weevils.

Main Methods:

• Starch gel electrophoresis was employed to analyze enzyme loci.
• Genotypes of individual weevils were determined across more than 25 loci.
• Allele frequencies were compared between parthenogenetic and diploid bisexual populations.

Main Results:

• Parthenogenetic weevil populations exhibit genetic differentiation, with genotypes within a population being more similar to each other than to those from different populations.
• Allele frequencies in parthenogenetic populations deviate from Hardy-Weinberg equilibrium, unlike diploid populations.
• The genetic data do not support a hybrid origin for parthenogenesis and polyploidy in weevils.

Conclusions:

• Apomictic parthenogenetic weevil populations can and do undergo genetic differentiation, demonstrating ongoing, albeit potentially slower, evolution.
• The genetic evidence strongly suggests that parthenogenesis within these weevil species is monophyletic, originating from a single ancestral lineage.
• The findings challenge previous hypotheses regarding the hybrid origin of parthenogenesis and polyploidy in weevils.