Genetic structuring of remnant forest patches in an endangered medicinal tree in North-western Ethiopia

Abstract

BackgroundHabitat loss and fragmentation may have detrimental impacts on genetic diversity, population structure and overall viability of tropical trees. The response of tropical trees to fragmentation processes may, however, be species, cohort or region-specific. Here we test the hypothesis that forest fragmentation is associated with lower genetic variability and higher genetic differentiation in adult and seedling populations of Prunus africana in North-western Ethiopia. This is a floristically impoverished region where all but a few remnant forest patches have been destroyed, mostly by anthropogenic means.ResultsGenetic diversity (based on allelic richness) was significantly greater in large and less-isolated forest patches as well as in adults than seedlings. Nearly all pairwise FST comparisons showed evidence for significant population genetic differentiation. Mean FST values were significantly greater in seedlings than adults, even after correction for within population diversity, but varied little with patch size or isolation.ConclusionsAnalysis of long-lived adult trees suggests the formerly contiguous forest in North-western Ethiopia probably exhibited strong spatial patterns of genetic structure. This means that protecting a range of patches including small and isolated ones is needed to conserve the extant genetic resources of the valuable forests in this region. However, given the high livelihood dependence of the local community and the high impact of foreign investors on forest resources of this region, in situ conservation efforts alone may not be helpful. Therefore, these efforts should be supported with ex situ gene conservation actions.

Leaf litter is essential for seed survival of the endemic endangered tree <i>Pouteria splendens</i> (Sapotaceae) from central Chile

“…Morales et al (2015), suggest that the genetic population pattern found might be the result of a recent process of habitat fragmentation and loss. Genetic variation among adult tree plants may reflect prefragmentation effect, whereas contemporary gene flow patterns will be observable among seedlings (Yineger et al, 2014). Consequently, it would be interesting to contrast the genetic pattern found in adult trees with the genetic variability in seedlings of P. splendens, since new generations might reflect patterns of more restricted gene flow through seeds.…”

Gene dispersal inference across forest patches in an endangered medicinal tree: comparison of model-based approaches

“…Factors such as these, in addition to others, such as habitat loss, reduction in population size, and loss of alleles, have the potential to cause limited seed dispersal among the extant populations. Indeed, our recent work (Yineger, Schmidt & Hughes, ) has demonstrated the potential limitation of gene flow among fragmented populations in north‐western Ethiopia, the current study region. However, this gene flow limitation was based on assessments of F ST and the proportion of first generation migrants as determined in GENECLASS, version 2.0 (Piry et al ., ), which does not take into account equilibrium conditions.…”

“…Details of the DNA isolation, amplification conditions, and allele scoring, as well as tests for null alleles, stuttering or large allele dropout, linkage disequilibrium and Hardy–Weinberg equilibrium, are reported in Yineger et al . ().…”

“…The historical pattern of IBD at the population level for the study region has been reported previously (Yineger et al ., ). Here, the pattern at the individual level is presented for seedlings and adults at multiple forest patches.…”

Monitoring age‐related trends in genomic diversity of Australian lungfish

“…The pattern of increased diversity with age in brown trout was suggested to be a product of viability selection against inbred individuals that are less likely to survive to old age (Labonne et al., ). Genetic diversity in forest trees has also been shown to vary among age classes, with older trees exhibiting higher diversity than seedling cohorts, a pattern attributed to a negative impact of recent forest fragmentation on recruitment success (Kettle et al., ; Yineger, Schmidt, & Hughes, ).…”