Abstract
Habitat loss and the illegal exploitation of natural resources are among the main drivers of species extinction around the world. These disturbances act at different scales, once changes in the landscape composition and configuration operate at large scales and exploitation of natural resources at local scales. Evidence suggests that both scales are capable of triggering genetic erosion in the remaining populations. However, most of the studies so far did not evaluate simultaneously the effects of these disturbances on genetic diversity and structure of plants. In this study, we used a multiple scale approach to empirically evaluate the impacts caused by local and landscape scale disturbances in the genetic diversity and structure of an endangered palm tree, Euterpe edulis. We sampled and genotyped with microsatellite markers 544 juveniles of E. edulis in 17 fragments of Atlantic Forest in Brazil. In addition, we estimated the local logging rate and the forest cover and isolation at landscape scale. We found that the palm populations have not undergone any recent bottleneck events and that only logging intensification had affected the fixation index and the number of private alleles. Additionally, we did not detect any evidence of spatial genetic structure or genetic divergence associated with environmental disturbance variables at different scales. However, we identified distinct genetic clusters, which may indicate a reduction of gene flow between fragments that were previously a continuous habitat. Our results show that local disturbances, which act directly on population size reduction, such as logging, modified the genetic diversity more rapidly, whereas genetic structure is probably more influenced by large-scale modifications. In this way, to maximize the conservation efforts of economically exploited species, we recommend to increase the inspection to reduce the illegal exploitation, and reforestation of degraded areas, in order to increase the gene flow in Atlantic Forest fragments.
Highlights
The conversion of natural environments into anthropogenic landscapes is one of the main causes of biodiversity loss worldwide (Laurance et al, 2014; Newbold et al, 2015; Miraldo et al, 2016)
We detected a total number of 347 alleles in the 17 loci by the 544 juvenile individuals from all 17 E. edulis populations evaluated
Our study represent a step forward in filling this gap, since it simultaneously evaluated the impacts of human activities at landscape and local scales on the genetic diversity of E. edulis populations in the Atlantic Forest
Summary
The conversion of natural environments into anthropogenic landscapes is one of the main causes of biodiversity loss worldwide (Laurance et al, 2014; Newbold et al, 2015; Miraldo et al, 2016). The remaining forest patches are being reduced and isolated with negative consequences for species diversity. In this context, the remaining populations are prone to gene flow decrease, alleles loss due to genetic drift, and inbreeding depression. The remaining populations are prone to gene flow decrease, alleles loss due to genetic drift, and inbreeding depression The consequence of these genetic changes might be a lower ability to adapt to further environmental changes (Bijlsma and Loeschcke, 2012; Fountain et al, 2016; Rhoads et al, 2017; Browne and Karubian, 2018). Several studies have corroborated this prediction (Dixo et al, 2009; Zhang et al, 2012; Wood et al, 2017), the intensity and the velocity of the response to impacts vary according to life history and environmental characteristics (Vranckx et al, 2012; Lino et al, 2019)
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