Guimarães M., Torres A.L.Q., Serra A.C.S., Coutinho R.A., Americo J.A., de Freitas Rebelo M.

The comprehension of demographic parameters of invasive bivalve species is fundamental to achieve successful management strategies. Sex ratio is a central parameter of population structure, directly influencing survival, reproduction and abundance, and thus, knowledge on the proportion of sexes can help understand populations of invasive bivalves, predict future scenarios and mitigate invasion. We performed a systematic review and meta-analysis to (i) understand how sex ratio varies among invasive freshwater bivalves and to (ii) assess the effects of seasonality and temperature on the sex ratio of the golden mussel, Limnoperna fortunei, an invasive species in South America. We examined scientific publications and the gray literature using Dimensions, Google Scholar, Lens and Periódicos Capes with structured and unstructured searches, combining different terms restricted to invasive and wild populations of adult freshwater bivalves. We assessed heterogeneity in articles using I2 and Q statistics. We compared the proportion of females among species and the effects of seasonality and temperature on the proportion of golden mussel females using GLMM. We found information for five invasive species in 1600 documents. We included 19 articles in the systematic review and 18 in the meta-analysis. Sex ratio was 1:1 in four species of invasive bivalves, Dreissena bugensis, D. polymorpha, L. fortunei, Sinanodonta woodiana, and female-biased in Corbicula fluminea, which influenced the overall sex ratio (proportion of females = 0.55, CI 0.53 – 0.58). According to the meta-regression, seasonality was important on sex ratio of the golden mussel, with the greatest proportion of females found in the winter and autumn. Temperature presented a negative, but non-significant, effect on the proportion of females. Our results suggest similar proportion of sexes among most freshwater invasive species studied and seasonality influencing the golden mussel sex ratio. Different environmental factors may influence local sex ratio, suggesting space-time variation.