WHY DO FEMALES MATE WITH MORE THAN ONE MALE?
Recent studies in the field of sexual selection revealed that polyandry (a female mating with more than one male) is far more common than traditionally thought. However, the evolution and maintenance of polyandry remains an intriguing and unresolved topic. I study female polyandry in – predominantly, but not only! – spiders with particular focus on understanding the evolutionary mechanisms driving female mating patterns, in particular whether females gain benefits (material or genetic) by engaging in multiple mating.
I use i) laboratory mating experiments to study female behaviour and fitness to assess the relationship between genetic and material benefits, showing as for the nuptial feeding spider Pisaura mirabilis that females that gain material donations as food from their mating partners may also gain notable genetic advantages for their offspring; ii) field studies to assess the ecological factors that affect encounter rates among males and females, such as mortality rate, sex ratio and spatial distribution of individuals, which influence the mating strategies adopted by both sexes as shown for the subsocial spiders Stegodyphus lineatus and Stegodyphus bicolor; and finally I conduct iii) paternity analysis using molecular methods to assess patterns of parentage and polyandry in the wild in order to understand whether genetic benefits in the form of inbreeding avoidance apply in naturally inbreeding systems as Stegodyphus lineatus and to understand the post-copulatory mechanisms used by females to control for the fertilization of their eggs to avoid inbreeding, showing that females control sperm stored by multiple males to bias paternity of their offspring in favour of the preferred male.
Dr. Cristina Tuni is an assistant professor at LMU Munich. You can read about her current research here.