Genetic structure of an insect-pollinated and bird-dispersed tropical tree in vegetation fragments and corridors: implications for conservation
In the vegetation corridors that connect small remnants of undisturbed primary forest in the Lavras landscape (Brazil), Protium spruceanum is a representative of a mass-flowering insect-pollinated and bird-dispersed tree. Allozyme variation was quantified from five forest remnants (N = 150) from secondary vegetation corridors linking them (N = 80) to generate information for genetic conservation. The species adhered to H-W equilibrium in all fragments in most of the loci. The results indicated high gene diversity in the fragments $$({\hat{H}}_{\rm e}=0.381{-}0.507)$$ and corridors $$({\hat{H}}_{\rm e}=0.336{-}0.470),$$ positively correlated with the plant density (r = 0.742, R2 = 0.551, d.f. = 4). We did not find evidence of inbreeding within fragments $$(\hat{f}=-0.188, P<0.05)$$ nor overall $$(\hat{F}=-0.101, P<0.05).$$ The genetic differentiation among remnants was low $$(\hat{\theta}_{\rm p}=2.8\%).$$ Evidence of recent bottlenecks by anthropogenic disturbance was detected in fragments (P < 0.05, Wilcoxon sign-rank test). The minimal viable population was estimated for conservation in situ, indicating fragments with possibilities of maintaining genetic equilibrium diversity in the short term (except F3) and in the long term (only F5). The $$\hat{N}_{\rm e}/N$$ ratios was also calculated to contribute to vegetation enrichment, area recovery or creation of new vegetation corridors. We found high levels of gene diversity in the vegetation corridors, genetic identity with the fragments and absence of inbreeding. Thus, our results suggest that landscape management strategies should therefore consider both the creation of new vegetation corridors and the protection of extant ones.