Lessons from a palm: genetic diversity and structure in anthropogenic landscapes from Atlantic Forest, Brazil

Abstract

Habitat loss threatens biodiversity in tropical forests, having harmful effects on population dynamics and, ultimately, determining the evolutionary destiny of species. Thus, understanding how habitat loss affects microevolutionary processes is an important step in the conservation of genetic resources. However, few studies have explored landscape genetics for plants in tropical environments. Our study evaluated the effects of a landscape-scale reduction in forest cover on genetic diversity and structure of Euterpe edulis (Arecaceae). The research was conducted in Atlantic Forest landscapes in Northeastern Brazil. We randomly chose 16 forest sites, each located in a 13 km 2 landscape with forest cover ranging from 6 to 83 %. After a survey of adults and seedlings in each sampling site, we found a minimum of five individuals of E. edulis at nine sites and sampled leafs from all adults within a 15 9 400 m plot and all seedlings within a 2 9 400 m subplot in each sampling site. We found that the gradient of remaining forest cover at the landscape scale did not affect the genetic diversity measured by any of the descriptors analyzed and each sampling site still harbored populations with high levels of genetic variability. However, we detected the presence of two distinct genetic groups with signs of admixture; the structural pattern of these groups differed between adults and seedlings, mainly in less forested landscapes areas. We believe that E. edulis is a good example of a tropical palm that is experiencing local extirpation before suffering loss of genetic alterations.

Landscape‐scale deforestation decreases gene flow distance of a keystone tropical palm, Euterpe edulis Mart (Arecaceae)

“…Such low SGS converges with the previous result reporting high genetic variability within these same populations of E. edulis (Santos et al. ). In addition, the low levels of SGS found in E. edulis seedling populations within a gradient of deforestation may occur due to different ecological processes.…”

“…Additionally, the contemporary gene flow results converging with results from F ST analyzes (Santos et al. ) and SGS. Our results indicated low spatial genetic structure that is characteristic of species with long‐distance dispersal, and little genetic differentiation among populations ( F ST ), probably an indication of high rates of gene flow.…”

“…Moreover, although forest loss may not affect the density of individuals (Santos et al. ), we found a lower proportion of seedlings with an assigned parent in more forested landscapes, indicating that gene flow is occurring outside our sample plot. However, in landscapes with less than 19% of forest cover, we found less than five individuals of E. edulis .…”

“…We emphasize that a previous study has revealed a likely time lag between landscape change and genetic diversity loss in populations of E. edulis in the same study areas in southern Bahia (Santos et al. ). Now we have indication that the gene flow is the genetic parameter that first experiences the negative influence of such anthropogenic disturbances, measured as landscape‐scale forest loss.…”

“…Therefore, although the E. edulis populations evaluated are still harboring high levels of genetic diversity as described by Santos et al. (), such populations are experiencing a reduction in contemporary gene flow.…”