THE EVOLUTION OF REPRODUCTIVE ISOLATION AS A CORRELATED CHARACTER UNDER SYMPATRIC CONDITIONS: EXPERIMENTAL EVIDENCE

Area of Science:

• Evolutionary Biology
• Speciation Research
• Genetics

Background:

• Sympatric speciation, the evolution of new species from a single ancestral species while inhabiting the same geographic region, remains a complex area of evolutionary biology.
• Reproductive isolation is a key factor in speciation, but the mechanisms by which it evolves, particularly under sympatric conditions, are actively investigated.

Purpose of the Study:

• To test the hypothesis that sympatric speciation is genetically feasible when reproductive isolation evolves indirectly as a correlated character.
• To investigate if disruptive selection on habitat preference can drive sympatric speciation in a model organism.

Main Methods:

• Utilized Drosophila melanogaster as a model system for experimental evolution.
• Conducted a 35-generation experiment involving a complex habitat maze to impose disruptive selection on habitat preference.
• Monitored the development of reproductive isolation between subpopulations occupying distinct spatiotemporal habitats.

Main Results:

• Achieved complete reproductive isolation between subpopulations of Drosophila melanogaster after 35 generations.
• Observed that reproductive isolation arose indirectly as a correlated character to habitat preference.
• Identified that offspring mating locally within their parents' selected habitat was the primary mechanism driving isolation, reducing migration.

Conclusions:

• Demonstrated the genetic feasibility of sympatric speciation under conditions of disruptive habitat selection.
• Provided experimental evidence that indirect selection on habitat preference can lead to the evolution of reproductive isolation and potentially new species.
• Highlighted the role of reduced gene flow, mediated by habitat-specific mating behavior, in facilitating sympatric speciation.