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

Abstract

(Genetic differentiation of the neotropical tree species Protium spruceanum (Benth.) Engler (Burseraceae) between fragments and vegetation corridors in Brazilian Atlantic forest). 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-fl owering/insect-pollinated and bird-dispersed tree. Genetic diversity was analyzed from 230 individuals in fi ve fragments (1 to 11.8 ha) and four corridors (460 to 1000 m length) using allozyme loci. We did not fi nd evidence of inbreeding within fragments or corridors, but the proportion of heterozygotes (ƒ) were signifi cantly 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 fl ow via seeds and pollen. Due to the consistently low differentiation observed among them and the absence of a signifi cant 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.