Landscape barriers to pollen and seed flow in the dioecious tropical tree Astronium fraxinifolium in Brazilian savannah.
PLoS One 2021;
16:e0255275. [PMID:
34339479 PMCID:
PMC8336915 DOI:
10.1371/journal.pone.0255275]
[Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 07/14/2021] [Indexed: 11/19/2022] Open
Abstract
Gene flow studies provide information on gene exchange between populations, which
is essential for developing genetic conservation strategies. Such analyses
enable a better understanding of the life history and seed and pollen dispersal
mechanisms of plant species. In this study, we investigate pollen and seed flow
in a regenerant population of the pioneer species Astronium
fraxinifolium in an area degraded during the construction of a
hydroelectric dam. We mapped, sampled, sexed, and genotyped 386 individuals in
the regenerant population (RP), as well as 128 adult trees located along two
highways adjacent to the degraded area; one in Mato Grosso do Sul State (MS) and
other in São Paulo State (SP). Parentage analyses was carried out for 370
individuals of the RP population, using as putative parents 348 individuals from
RP and all 128 individuals sampled in MS and SP. Based on parentage analysis and
eight microsatellite loci, our analyses revealed that for individuals of the RP
with an identified father (pollen donor), 1.1% of the pollen was dispersed up to
532 m, while for those with an identified mother (seed donor), 0.5% of seeds
were dispersed up to 4,782 m. However, a large proportion of pollen (76.5%) and
seeds (57%) immigrated from trees outside the sampled populations. Pollen and
seeds were dispersed through a pattern of isolation by distance. Genetic
diversity was significantly similar between adults of both highway populations
and individuals from RP, with significant levels of inbreeding detected only in
RP. Our results demonstrate that the nearest trees contributed pollen and seeds
for the recovery of the degraded area, indicating reproductive spatial isolation
among the sampled populations due to the damming of the river. Such results help
to understand the process of regeneration for A.
fraxinifolium in regenerant populations to inform
strategies for conservation and environmental recovery with this species.
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