Gone with the wind: Negative genetic and progeny fitness consequences of habitat fragmentation in the wind pollinated dioecious treeBrosimum alicastrum

Abstract

Premise Habitat fragmentation negatively affects population size and mating patterns that directly affect progeny fitness and genetic diversity; however, little is known about the effects of habitat fragmentation on dioecious, wind pollinated trees. We assessed the effects of habitat fragmentation on population sex ratios, genetic diversity, gene flow, mating patterns, and early progeny vigor in the tropical dioecious tree, Brosimum alicastrum. Methods We conducted our study in three continuous and three fragmented forest sites in a Mexican tropical dry forest. We used eight microsatellite loci to characterize the genetic diversity, gene flow via pollen distances, and mean relatedness of progeny. We compared early progeny vigor parameters of seedlings growing under greenhouse conditions. Results Sex ratios did not deviate from 1:1 between habitat conditions except for one population in a fragmented habitat, which was female biased. The genetic diversity of adult trees and their offspring was similar in both habitat conditions. Pollen gene flow distances were similar across habitat types; however, paternity correlations were greater in fragmented than in continuous habitats. Germination rates did not differ between habitat conditions; however, progeny from fragmented habitats produced fewer leaves and had a lower foliar area, total height, and total dry biomass than progeny from continuous habitats. Conclusions Changes in mating patterns because of habitat fragmentation have negative effects on early progeny vigor. We conclude that negative habitat fragmentation effects on mating patterns and early progeny vigor may be a serious threat to the long‐term persistence of tropical dioecious trees.

Genetic diversity and population structure of an insect‐pollinated and bird‐dispersed dioecious tree Magnolia kwangsiensis in a fragmented karst forest landscape

“…The fragmentation of plant populations, especially those of rare and endemic endangered species, might lead to inbreeding depression, fixation of deleterious mutations, and loss of adaptive genotypes (Aguilar‐Aguilar et al., 2023 ; Isagi et al., 2007 ; Martín‐Hernanz et al., 2019 ). Furthermore, long‐term fragmentation of plant populations is predicted to increase the chances of population differentiation due to genetic drift (Aguilar et al., 2008 ; Schultz & Scofield, 2009 ).…”