Sexual selection's impacts on ecological specialization: an experimental test.

Area of Science:

• Evolutionary biology
• Ecology
• Animal behavior

Background:

• Ecological specialization reduces competition and can drive the evolution of distinct ecomorphs.
• Understanding the influence of sexual selection on ecological specialization is key to explaining trait evolution and speciation.

Purpose of the Study:

• To investigate the population-level effects of sexual selection on ecological specialization in spadefoot toad tadpoles.
• To determine how mate choice influences the development and fitness of alternative ecomorphs under resource competition.

Main Methods:

• Experimental manipulation of sexual selection by controlling female mating preferences (preferred vs. non-preferred males).
• Exposing tadpoles from these pairings to resource competition in controlled mesocosm environments.
• Assessing ecomorph distribution, trait integration, fitness, and natural selection patterns between sexual selection treatments.

Main Results:

• Ecomorph distribution was similar across sexual selection treatments.
• Sexual selection led to poorer trait integration and lower fitness in the specialized carnivore morph.
• Disruptive and directional natural selection were weaker when sexual selection was present.

Conclusions:

• Sexual selection can inhibit adaptation to resource competition and hinder ecological specialization.
• This effect is more pronounced when female mate choice provides fitness benefits that outweigh costs of producing less competitive offspring.
• Sexual selection's impact on specialization is context-dependent, influenced by factors like ecological opportunity and competitor density.