Effects of fragmentation and anthropic pressure on the genetic structure of Canthon (Peltecanthon) staigi (Coleoptera: Scarabaeidae) populations in the Atlantic Forest domain

Abstract

Canthon (Peltecanthon) staigi is an endemic dung beetle from the east coast of South America (Brazil, Paraguay and Argentina). It is a stenotopic species abundant in different habitats of the Atlantic Forest. In this study, we analyzed the influence of fragmentation and environmental changes on the population genetic structure of C. (P.) staigi using inter-simple sequence repeat polymorphisms, and the consequences for management and conservation. The expected heterozygosity (HE) ranged from 0.16 (restinga, TAM population) in the smallest and most disturbed forest patch to 0.24 (“brejo de altitude”, PES population) in the largest and most conserved area. Based on the low coefficient of genetic population differentiation (FST = 0.07) and large molecular variance within populations, we suggest historical gene flow among C. (P.) staigi populations. Additionally, the model ƒ = 0, which corresponds to a lack of or very low inbreeding rate, is another factor that indicates gene flow among populations. Two genetic traits (K = 2) were related with anthropic disturbance, suggesting that the six studied populations are genetically divided into two separate units, one related to preserved and another to disturbed areas. Based on these data, the recent habitat fragmentation may not have led to genetic differentiation, but rather the environmental modifications caused by anthropic pressure seem to be strongly related to the loss of genetic diversity in the species C. (P.) staigi.