Spatial variation in adult sex ratio across multiple scales in the invasive golden apple snail, Pomacea canaliculata.

Meng Xu,Jaimie T A Dick,Yexin Yang,Xidong Mu,Jianren Luo,Du Luo,Miao Fang,Dangen Gu,Yinchang Hu,Hongmei Song

doi:10.1002/ece3.2043

Abstract

Adult sex ratio (ASR) has critical effects on behavior and life history and has implications for population demography, including the invasiveness of introduced species. ASR exhibits immense variation in nature, yet the scale dependence of this variation is rarely analyzed. In this study, using the generalized multilevel models, we investigated the variation in ASR across multiple nested spatial scales and analyzed the underlying causes for an invasive species, the golden apple snail Pomacea canaliculata. We partitioned the variance in ASR to describe the variations at different scales and then included the explanatory variables at the individual and group levels to analyze the potential causes driving the variation in ASR. We firstly determined there is a significant female‐biased ASR for this species when accounting for the spatial and temporal autocorrelations of sampling. We found that, counter to nearly equal distributed variation at plot, habitat and region levels, ASR showed little variation at the town level. Temperature and precipitation at the region level were significantly positively associated with ASR, whereas the individual weight, the density characteristic, and sampling time were not significant factors influencing ASR. Our study suggests that offspring sex ratio of this species may shape the general pattern of ASR in the population level while the environmental variables at the region level translate the unbiased offspring sex ratio to the female‐biased ASR. Future research should consider the implications of climate warming on the female‐biased ASR of this invasive species and thus on invasion pattern.

Highlights

Adult sex ratio (ASR), defined as the ratio of adult males to adult females in a population, is a central concept in population biology (Bessa-Gomes et al 2004; Le Galliard et al 2005; Ewen et al 2011; Szekely et al 2014b)
In this study, using the generalized multilevel models, we investigated the variation in ASR across multiple nested spatial scales and analyzed the underlying causes for an invasive species, the golden apple snail Pomacea canaliculata
We examine the spatial pattern of ASR variation for a highly invasive species, the golden apple snail Pomacea canaliculata (Gastropoda, Ampullariidae), across multiple nested spatial scales

Summary

Introduction

Adult sex ratio (ASR), defined as the ratio of adult males to adult females in a population, is a central concept in population biology (Bessa-Gomes et al 2004; Le Galliard et al 2005; Ewen et al 2011; Szekely et al 2014b). ASR has critical effects on behavior, mate competition and life history and has implications for population demography and biodiversity conservation (Le Galliard et al 2005; Kokko and Jennions 2008; Liker et al 2013; Szekely et al 2014a; Pipoly et al 2015). With male-biased ASR, the courtship behavior and male–male competition may intensify (Leftwich et al 2012); a male-biased ASR may increase the rates of aggression and harassment of males to females, which in turn resulting in higher mortality of females (Le Galliard et al 2005). Trinidad guppy Poecilia reticulata populations in some streams are heavily male-biased, while others exhibit unbiased or female-biased ASR

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