Sexual cannibalism and population viability. Issue 13 (24th June 2018)

• Record Type: Journal Article
• Authors: Fisher, Adam M.; Cornell, Stephen J.; Holwell, Gregory I.; Price, Tom A. R.
• Is Part Of: Ecology and evolution. Volume 8:Issue 13(2018)
• Page Start: 6663
• Page End: 6670
• Publication Date: 2018-06-24
• Subjects: arachnid -- cannibalism -- extinction -- extinction vortex -- mantis -- population growth -- population survival; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.4155
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Some behaviours that typically increase fitness at the individual level may reduce population persistence, particularly in the face of environmental changes. Sexual cannibalism is an extreme mating behaviour which typically involves a male being devoured by the female immediately before, during or after copulation, and is widespread amongst predatory invertebrates. Although the individual‐level effects of sexual cannibalism are reasonably well understood, very little is known about the population‐level effects. We constructed both a mathematical model and an individual‐based model to predict how sexual cannibalism might affect population growth rate and extinction risk. We found that in the absence of any cannibalism‐derived fecundity benefit, sexual cannibalism is always detrimental to population growth rate and leads to a higher population extinction risk. Increasing the fecundity benefits of sexual cannibalism leads to a consistently higher population growth rate and likely a lower extinction risk. However, even if cannibalism‐derived fecundity benefits are large, very high rates of sexual cannibalism (>70%) can still drive the population to negative growth and potential extinction. Pre‐copulatory cannibalism was particularly damaging for population growth rates and was the main predictor of growth declining below the replacement rate. Surprisingly, post‐copulatory cannibalism had a largely positive effect on population growth rate when fecundity benefits were present. This study is the first to formally estimate the population‐level effects of sexual cannibalism. We highlight the detrimental effect sexual cannibalism may have on population viability if (1) cannibalism rates become high, and/or (2) cannibalism‐derived fecundity benefits become low. Decreased food availability could plausibly both increase the frequency of cannibalism, and reduce the fecundity benefit of cannibalism, suggesting that sexual cannibalism may increase the risk of population collapse in the face of environmental change. Abstract : Sexual cannibalism is common in predatory invertebrates, but very little is known about the impact it has on population survival. Here, we model the impact of pre‐ and post‐copulatory cannibalism on population growth rate, finding that high rates of sexual cannibalism, particularly before copulation, are likely to cause population decline. We suggest that degraded habitats make high rates of cannibalism more likely, and so sexual cannibalism may speed population decline and extinction in the face of environmental change.