Mate finding, Allee effects and selection for sex‐biased dispersal

• Published in: The Journal of animal ecology 2014-11, Vol.83 (6), p.1256-1267
• Main Authors: Shaw, Allison K, Kokko, Hanna, Coulson, Tim
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal behavior; Animal Distribution; Animal ecology; Animal reproduction; Animal, plant and microbial ecology; Animals; Biological and medical sciences; context‐dependent dispersal; Dispersal; Ecological genetics; Ecological modeling; Evolution; Evolutionary ecology; Female; Fundamental and applied biological sciences. Psychology; Gender bias; General aspects; Genetic Fitness; immigration; Male; Male animals; mate searching; Mating behavior; mating system; Mating systems; Models, Biological; monogamy; movement; philopatry; polygyny; Population Density; Population ecology; population growth; prediction; Restlessness; settlement; Sex Characteristics; Sex ratio; Sexual Behavior, Animal; sperm competition
• ISSN: 0021-8790; 1365-2656
• DOI: 10.1111/1365-2656.12232

Although dispersal requires context‐dependent decision‐making in three distinct stages (emigration, transit, immigration), these decisions are commonly ignored in simple models of dispersal. For sexually reproducing organisms, mate availability is an important factor in dispersal decisions. Difficulty finding mates can lead to an Allee effect where population growth decreases at low densities. Surprisingly, theoretical studies on mate finding and on sex‐biased dispersal produce opposing predictions: in the former, one sex is predicted to move less if the other sex evolves to search more, whereas in the latter, mate‐finding difficulties can select for less sex bias in dispersal when mate finding occurs after dispersal. Here, we develop a pair of models to examine the joint evolution of dispersal and settlement behaviour. Our first model resolves the apparent contradiction from the mate search and dispersal literatures. Our second model demonstrates that the relationship between mating system and sex‐biased dispersal is more complex than a simple contrast between resource defence monogamy and female defence polygyny. Our results highlight that a key factor is the timing of mating relative to dispersal (before, during, or after). We also show that although movement has the potential to alleviate a mate‐finding Allee effect, in some cases, it can actually exacerbate the effect.