Consistent male-male paternity differences across female genotypes

Area of Science:

• Evolutionary biology
• Animal behavior
• Reproductive strategies

Background:

• Male reproductive success in species with internal fertilization is influenced by sperm competition.
• Previous research in Peron's tree frog (Litoria peronii) indicated that male-female genetic relatedness affects paternity.
• The consistency of male mating performance across different females was previously unexamined.

Purpose of the Study:

• To investigate if a male's siring success with one female predicts his success with another.
• To determine the relative importance of innate male siring ability versus genetic relatedness in determining paternity.

Main Methods:

• Experimental sperm competition trials were conducted with Peron's tree frogs (Litoria peronii).
• Male sperm concentration was standardized, and viable sperm proportions were statistically controlled.
• Male-specific differences in siring success were measured across multiple females.

Main Results:

• A significant positive correlation was found between a male's siring success difference with one female and his success difference with another.
• Among-male differences in innate siring ability explained over 62% of the variance in siring differences.
• Male-female genetic relatedness had a lesser influence on siring success compared to innate male differences.

Conclusions:

• Male siring success in this species is largely determined by consistent, individual differences in male mating ability.
• Innate male traits appear to be more critical than genetic relatedness in determining paternity outcomes in sperm competition.
• These findings highlight the importance of consistent individual variation in reproductive strategies.