2003/07/01 by Maydianne C. B. Andrade · 1 citation
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · Environmental Science · #Animal Behavior and Reproduction #Insect and Arachnid Ecology and Behavior #Fish Ecology and Management Studies #Biology #Sacrifice #Mating #Cannibalism #Zoology #Adaptive value #Mate choice #Ecology #Predation
paper · pdf · doi:10.1093/beheco/arg015
openalex publication_date 2003/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Male redback spiders twist their abdomens onto the fangs of their mates during copulation and, if cannibalized (65% of matings), increase their paternity relative to males that are not cannibalized. The adaptive male sacrifice hypothesis proposes that this increased reproductive payoff from a single mating outweighs the residual reproductive value of a cannibalized male, because high mortality during mate searching restricts alternative mating opportunities. It has been reported that redback male residual reproductive value is low because males are functionally sterile after one mating—a putative intrinsic constraint that could arguably favor self-sacrifice in the absence of ecological restrictions on multiple mating. However, sterility and self-sacrifice may both arise as aspects of a terminal investment strategy if the probability of multiple mating is sufficiently low. Here I report field data that support the adaptive male sacrifice hypothesis. More than 80% of redback males die without finding a potential mate in nature. Data from two observational field studies and one release experiment suggest that in the absence of cannibalism, male redbacks would expect fewer than one mating opportunity in a lifetime. This expectation was not significantly higher for a large male or one in good condition. A simple quantitative analysis confirms that even if males are assumed to be fertile throughout life, the measured mortality rate during mate search in combination with previously documented paternity benefits of cannibalism is sufficient to ensure that self-sacrifice is adaptive for male redback spiders.