Habitat Loss Does Not Always Entail Negative Genetic Consequences

Abstract

Although habitat loss has large, consistently negative effects on biodiversity, its genetic consequences are not yet fully understood. This is because measuring the genetic consequences of habitat loss requires accounting for major methodological limitations like the confounding effect of habitat fragmentation, historical processes underpinning genetic differentiation, time-lags between the onset of disturbances and genetic outcomes, and the need for large numbers of samples, genetic markers, and replicated landscapes to ensure sufficient statistical power. In this paper we overcame all these challenges to assess the genetic consequences of extreme habitat loss driven by mining in two herbs endemic to Amazonian savannas. Relying on genotyping-by-sequencing of hundreds of individuals collected across two mining landscapes, we identified thousands of neutral and independent single-nucleotide polymorphisms (SNPs) in each species and used these to evaluate population structure, genetic diversity, and gene flow. Since open-pit mining in our study region rarely involves habitat fragmentation, we were able to assess the independent effect of habitat loss. We also accounted for the underlying population structure when assessing landscape effects on genetic diversity and gene flow, examined the sensitivity of our analyses to the resolution of spatial data, and used annual species and cross-year analyses to minimize and quantify possible time-lag effects. We found that both species are remarkably resilient, as genetic diversity and gene flow patterns were unaffected by habitat loss. Whereas historical habitat amount was found to influence inbreeding; heterozygosity and inbreeding were not affected by habitat loss in either species, and gene flow was mainly influenced by geographic distance, pre-mining land cover, and local climate. Our study demonstrates that it is not possible to generalize about the genetic consequences of habitat loss, and implies that future conservation efforts need to consider species-specific genetic information.

Combining genotype, phenotype, and environmental data to delineate site‐adjusted provenance strategies for ecological restoration

“…We used flow cytometry to estimate haploid genome size in both (Yang et al, 2010) and pairwise geographic distance, as in (Carvalho et al, 2019).…”

Agricultural Landscape Heterogeneity Matter: Responses of Neutral Genetic Diversity and Adaptive Traits in a Neotropical Savanna Tree

“…Impacts of fragmentation and habitat loss on plant genetic diversity are still poorly understood, despite the increase in the number of studies in recent years ( Storfer et al, 2010 ; Manel and Holderegger, 2013 ). Several works point out the decreasing in genetic diversity due to fragmentation process (e.g., Jump and Peñuelas, 2006 ; Aparicio et al, 2012 ; Carvalho et al, 2015 ; Gómez-Fernández et al, 2016 ; Collevatti et al, 2020a ), while others found no reduction in genetic diversity (e.g., Hall et al, 1996 ; Collevatti et al, 2001 ; Bacles et al, 2005 ; Winkler et al, 2011 ; Carvalho et al, 2019 ; Soares et al, 2019 ). The variation in fragmentation and habitat loss effects on genetic diversity may be due to differences in life history because each species respond to landscape changes according to their dispersal capacity and ecological requirements ( Prevedello and Vieira, 2010 ; Eycott et al, 2012 ).…”

Impacts of Four Decades of Forest Loss on Vertebrate Functional Habitat on Borneo

“…Movement is modulated by the quality of the intervening habitat matrix (Renjifo, 2001), the size and distribution of remnant habitat patches (Saura et al, 2014), and the dispersal capacity of the species (Tscharntke et al, 2012). A functionally connected landscape is essential for maintaining healthy populations across generations because it provides access to resources, sustains metapopulations, and supports genetic diversity through gene flow (Templeton et al, 1990;Fahrig, 2003;Sodhi et al, 2011). Reductions in population size, dispersal of young individuals, and mobility of species in fragmented landscapes also alters ecological processes such as pollination and seed dispersal (Ghazoul, 2005;Magrach et al, 2014).…”