Genetic differentiation of the neotropical tree species Protium spruceanum (Benth.) Engler (Burseraceae) between fragments and vegetation corridors in Brazilian Atlantic forest

Abstract

We studied patterns of genetic differentiation in a connected landscape with an interesting history of human habitat conversion that began two centuries ago, during the Brazilian colonization period. In the fragments of Brazilian Atlantic seasonal forest and corridors of secondary forest, Protium spruceanum is an abundant native, mass-flowering/insect-pollinated and bird-dispersed tree. Genetic diversity was analyzed from 230 individuals in five fragments (1 to 11.8 ha) and four corridors (460 to 1000 m length) using allozyme loci. We did not find evidence of inbreeding within fragments or corridors, but the proportion of heterozygotes (<IMG SRC="/img/revistas/abb/v23n4/a28simb1.gif" WIDTH=287 HEIGHT=96>) were significantly higher in fragments than in the secondary vegetation corridors, based on Goudet's G-test (P = 0.036). Genetic differentiation was low and no pattern of isolation by distance was detected. All fragments generally present low historical genetic differentiation with corridors that they are connected, indicating possible gene flow via seeds and pollen. Due to the consistently low differentiation observed among them and the absence of a significant reduction in gene diversity in second-growth forests, we conclude that corridors of second-growth forests would be an important alternative in the genetic connection of isolated forest fragments.

A regeneração natural como indicadora de conservação, de sustentabilidade e como base do manejo adaptativo de fragmentos florestais remanescentes inseridos em diferentes matrizes agrícolas

“…ISHANNONsub = Índice de Shannon-Weaver; NESP_M 2 sub = número de espécies por metro quadrado, em cada sub-transecto; N_HAsub = número de indivíduos por hectare, calculados por sub-transecto. Sub-transectos: 1: 10 metros de distância da borda; 2: 20 metros de distância da borda; 3: 30 metros de distância da borda Matriz Sub-transecto Abundância ISHANNONsub NESP_M 2 sub N_HAsub (METZGER, 2000;UEZU et al, 2005;CABACINHA;CASTRO, 2009;SAMPAIO et al, 2010;CARVALHO, 2009;CHEUNG et al, 2010;ZURITA & BELLOCQ, 2010;CARMO et al, 2011;ROCHA;PASSAMANI;LOUZADA, 2011). Primeiro, a matriz pode atuar como um filtro seletivo para o movimento das espécies na paisagem.…”