Behavioral Correlates of Primates Conservation Status: Intrinsic Vulnerability to Anthropogenic Threats

Abstract

Behavioral traits are likely to influence species vulnerability to anthropogenic threats and in consequence, their risk of extinction. Several studies have addressed this question and have highlighted a correlation between reproductive strategies and different viability proxies, such as introduction success and local extinction risk. Yet, very few studies have investigated the effective impact of social behaviour, and evidence regarding global extinction risk remains scant. Here we examined the effects of three main behavioral factors: the group size, the social and reproductive system, and the strength of sexual selection on global extinction risk. Using Primates as biological model, we performed comparative analysis on 93 species. The conservation status as described by the IUCN Red List was considered as a proxy for extinction risk. In addition, we added previously identified intrinsic factors of vulnerability to extinction, and a measure of the strength of the human impact for each species, described by the human footprint. Our analysis highlighted a significant effect of two of the three studied behavioral traits, group size and social and reproductive system. Extinction risk is negatively correlated with mean group size, which may be due to an Allee effect resulting from the difficulties for solitary and monogamous species to find a partner at low densities. Our results also indicate that species with a flexible mating system are less vulnerable. Taking into account these behavioral variables is thus of high importance when establishing conservation plans, particularly when assessing species relative vulnerability.

Stochasticity in social structure and mating system drive extinction risk

“…Further, the second study also found that more flexible mating systems yielded lower extinction risks (Lootvoet et al. ), which is consistent with our finding that monogamous populations consistently experienced the highest extinction risks. The reduction in extinction risk at large group sizes under alpha pair monogamy in our model could represent the relative robustness of this mating system to fluctuations in group composition.…”

“…Under alpha pair monogamy, the results validated our initial prediction in that large group sizes reduced extinction risk in stochastic models. This result agrees with previous empirical research that has identified small group size as an important predictor of extinction risk in social mammals generally (Davidson et al 2009) and primates specifically (Lootvoet et al 2015). However, under both monogamy and polygynandry, extinction risk increased with group size, contrary to our prediction and previous empirical results (Davidson et al 2009, Lootvoet et al 2015.…”

“…This result agrees with previous empirical research that has identified small group size as an important predictor of extinction risk in social mammals generally (Davidson et al 2009) and primates specifically (Lootvoet et al 2015). However, under both monogamy and polygynandry, extinction risk increased with group size, contrary to our prediction and previous empirical results (Davidson et al 2009, Lootvoet et al 2015. One of these studies did not take mating system into account (Davidson et al 2009), which could partially explain the apparent discrepancy with our results.…”

“…) and primates specifically (Lootvoet et al. ). However, under both monogamy and polygynandry, extinction risk increased with group size, contrary to our prediction and previous empirical results (Davidson et al.…”

Impending extinction crisis of the world’s primates: Why primates matter

“…S9, A to C, and Supplementary Text). This result is likely due to the fact that related taxa share intrinsic aspects of their biology, such as body mass, life history, reproductive physiology, geographical distribution, dietary requirements, and behaviors ( 85 – 87 ). For example, several colobines ( Trachypithecus , Presbytis , and Simias ) in Southeast Asia are highly threatened island endemics and share biological traits known to increase their exposure and vulnerability to threats and extinction risks, such as relatively large body mass, diurnal behavior, and restricted geographic ranges.…”