Mate Guarding

• Inverse sexual dimorphism is where the male is bigger than the female in order to guard her
• When the male is smaller than the female (amphibians), he will guard before mating with her to compete with other males
• Advantages to mate guarding before copulation: parental certainty, wait until she is in oestrus, ensuring she is a good quality female, there might be more females than males
• 3 types of mate guarding: precopula, amplexus, and postcopula
• Postcopula guarding evolved through males mating with females who were closer to laying eggs, ovulating, being more successful
• Precopula is more common in male dominated populations, where the operational sex ratio is male biased
• Precopula mate guarding may be selected for when breeding is restricted in time, small proportion of females are receptive at a time, female receptivity is asynchronous
• Costs of precopula mate guarding is the males suffer physiological costs, more open to predation as in a pair they appear bigger, loss of time to search for other mates
• If OSR is male biased, precopula will be longer; if female biased then males more choosy and have shorter guard time
• Postcopula prevents multiple matings, ejection of sperm, parental certainty as last male precedence, can sacrifice himself to save offspring
• Some species of female store sperm, making the last male to mate with her the first fertiliser giving him a higher percentage of offspring - last male precedence
• In birds, song is a type of mate guarding wherein song rate will peak when females are most fertile as rival males will be deterred by guarder's song, males in better condition will produce more songs
• Mate guarding happens in humans, marriage being the ultimate guarding as it is common for just the woman to wear the ring
• Women exhibit more jealousy and mate guarding towards women who are near peak fertility, especially with attractive partners