Genetic Structure of Tree and Shrubby Species Among Anthropogenic Edges, Natural Edges, and Interior of an Atlantic Forest Fragment

Abstract

Two species, Psychotria tenuinervis (shrub, Rubiaceae) and Guarea guidonia (tree, Meliaceae), were used as models to compare the genetic structure of tree and shrubby species among natural edges, anthropogenic edges, and a fragment interior. There were significant differences between two genetic markers. For isozymes, P. tenuinervis presented greater heterozygosity (expected and observed) and a higher percentage of polymorphic loci and median number of alleles than G. guidonia. For microsatellites, there was no difference in genetic variability between the species. Only P. tenuinervis, for isozymes, showed differences in genetic variability among the three habitats. There was no genetic structure (F (ST) < 0.05) among habitats in both plant species for both genetic markers. Isozymes showed great endogamy for both plant species, but not microsatellites. The forest fragmentation may have negative effects on both spatial (among edges and interior) and temporal genetic variability.

Forest fragmentation and edge effects on the genetic structure ofClusia sphaerocarpaandC. lechleri(Clusiaceae) in tropical montane forests

“…Our study is also in line with Ramos et al . (2010) who reported no significant differences in genetic diversity neither for Psychotria tenuinervis nor for Guarea guidonia among fragment interior, natural and anthropogenic edge areas in an Atlantic Forest. Similarly, genetic diversity was similarly high in populations of Prunus africana growing in forest fragments and in continuous forests (Farwig et al .…”

“…Although Kramer et al (2008) reported a considerable body of literature that does not show effects of fragmentation on genetic variability in long-lived plant species, these effects may be visible only in some life stages (Ramos et al 2010, van Rossum & Triest 2006, van Geert et al 2008. Considering that fragmentation may have occurred after the adult plants had established, their genotype will reflect historical rather than current genetic patterns.…”

“…(2008) reported a considerable body of literature that does not show effects of fragmentation on genetic variability in long-lived plant species, these effects may be visible only in some life stages (Ramos et al . 2010, van Rossum & Triest 2006, van Geert et al . 2008).…”

Habitat fragmentation decreased the genetic variability of Trichilia elegans A. Juss. (Meliaceae) in southern Brazil

“…HAMRICK and LOVELESS (1986) found a H e of 0.13 and P of 32.2 % in Psychotria tenuinervis (Rubiaceae). RAMOS et al (2010) studied a local Psychotria tenuinervis population and found a H e of 0.35 and P of 71% for plants near the anthropogenic edge (50 m) and a H e of 0.25 and P of 50 % for plants of this population inside the fragment (200 m from the edge).…”

Genetic diversity in Atlantic Forest trees: fragmentation effects on Astronium graveolens (Anacardiaceae) and Metrodorea nigra (Rutaceae), species with distinct seed dispersal strategies

“…These results contrast with the common assumption that species with developed spatial dispersal abilities are less sensitive to isolation and reduction in fragment size than are species that have restricted spatial dispersal (Dupré & Ehrlén, 2002; Kolb & Diekmann, 2005; Alados et al ., 2010). Ramos et al . (2010) found similar results and stated that a low θ between remnant fragments is an indication of good level of gene flow among the habitats studied when the individuals were fertilized and dispersed.…”