Genetic diversity provides populations with the possibility to persist in ever‐changing environments, where selective regimes change over time. Therefore, the long‐term survival of a population may be affected by its level of genetic diversity. The Mexican howler monkey (
Crenate broomrape (
- NSF-PAR ID:
- 10370875
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 12
- Issue:
- 3
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract Alouatta palliata mexicana ) is a critically endangered primate restricted to southeast Mexico. Here, we evaluate the genetic diversity and population structure of this subspecies based on 83 individuals from 31 groups sampled across the distribution range of the subspecies, using 29 microsatellite loci. Our results revealed extremely low genetic diversity (H O = 0.21,H E = 0.29) compared to studies of otherA. palliata populations and to otherAlouatta species. Principal component analysis, a Bayesian clustering method, and analyses of molecular variance did not detect strong signatures of genetic differentiation among geographic populations of this subspecies. Although we detect small but significantF STvalues between populations, they can be explained by a pattern of isolation by distance. These results and the presence of unique alleles in different populations highlight the importance of implementing conservation efforts in multiple populations across the distribution range ofA. p. mexicana to preserve its already low genetic diversity. This is especially important given current levels of population isolation due to the extreme habitat fragmentation across the distribution range of this primate. -
Abstract The Hengduan Mountains region is a biodiversity hotspot known for its topologically complex, deep valleys and high mountains. While landscape and glacial refugia have been evoked to explain patterns of interspecies divergence, the accumulation of intra‐species (i.e., population level) genetic divergence across the mountain‐valley landscape in this region has received less attention. We used genome‐wide restriction site‐associated DNA sequencing (RADseq) to reveal signatures of Pleistocene glaciation in populations of
Thitarodes shambalaensis (Lepidoptera: Hepialidae), the host moth of parasiticOphiocordyceps sinensis (Hypocreales: Ophiocordycipitaceae) or caterpillar fungus” endemic to the glacier of eastern Mt. Gongga. We used moraine history along the glacier valleys to model the distribution and environmental barriers to gene flow across populations ofT .shambalaensis . We found that moth populations separated by less than 10 km exhibited valley‐based population genetic clustering and isolation‐by‐distance (IBD), while gene flow among populations was best explained by models using information about their distributions at the local last glacial maximum (LGML, 58 kya), not their contemporary distribution. Maximum likelihood lineage history among populations, and among subpopulations as little as 500 m apart, recapitulated glaciation history across the landscape. We also found signals of isolated population expansion following the retreat of LGMLglaciers. These results reveal the fine‐scale, long‐term historical influence of landscape and glaciation on the genetic structuring of populations of an endangered and economically important insect species. Similar mechanisms, given enough time and continued isolation, could explain the contribution of glacier refugia to the generation of species diversity among the Hengduan Mountains. -
Abstract Rare species of plants are especially vulnerable to extinction when populations are few, have small numbers of individuals, and are fragmented. Such conditions lead to a reduction in gene flow and genetic diversity, and encourage inbreeding depression. We conducted a study of the reproductive biology and population genetics of
Penstemon debilis (Plantaginaceae), a Federally Threatened species endemic to a small region of oil shale extraction in western Colorado, USA. Most of the habitat area is privately owned and undergoing natural gas extraction activities.Penstemon debilis reproduces both vegetatively and as an outcrosser that requires a pollen vector. Moderate levels of inbreeding, but no inbreeding depression, were found within populations ofP. debilis . Genetic divergence among the extant populations surveyed was moderate (F STvalues = 0.069–0.231;N m = 0.831–3.385) with levels of genetic diversity within populations relatively low compared to congeners with similar modes of pollination and reproductive biology. STRUCTURE analysis revealed three population clusters with some admixture among all extant populations. Genetic diversity within and amongP. debilis populations is similar to genetic diversity found for other rare and endemic outcrossing plant species. Our results are consistent with a pattern of recent population fragmentation or low levels of pollen‐mediated gene flow among populations in close proximity to one another. Conservation ofP. debilis will require cooperative management strategies between private landowners, government agencies, and concerned NGOs to preserve habitat for this rare species. -
Abstract Patterns of mating for the European corn borer (
Ostrinia nubilalis ) moth depend in part on variation in sex‐pheromone blend. The ratio of (E )‐11‐ and (Z )‐11‐tetradecenyl acetate (E11‐ and Z11‐14:OAc) in the pheromone blend that females produce and males respond to differs between strains ofO. nubilalis . Populations also vary in female oviposition preference for and larval performance on maize (C4) and nonmaize (C3) host plants. The relative contributions of sexual and ecological trait variation to the genetic structure ofO. nubilalis remains unknown. Host‐plant use (13C/14C ratios) and genetic differentiation were estimated among sympatric E and Z pheromone strainO. nubilalis males collected in sex‐pheromone baited traps at 12 locations in Pennsylvania and New York between 2007 and 2010. Among genotypes at 65 single nucleotide polymorphism marker loci, variance at a position in the pheromone gland fatty acyl‐reductase (pgfar ) gene at the locus responsible for determining female pheromone ratio (Pher ) explained 64% of the total genetic differentiation between males attracted to different pheromones (male response,Resp ), providing evidence of sexual inter‐selection at these unlinked loci. Principal coordinate, Bayesian clustering, and distance‐based redundancy analysis (dbRDA) demonstrate that host plant history or geography does not significantly contribute to population variation or differentiation among males. In contrast, these analyses indicate that pheromone response andpgfar ‐defined strain contribute significantly to population genetic differentiation. This study suggests that behavioural divergence probably plays a larger role in driving genetic variation compared to host plant‐defined ecological adaptation. -
Abstract The importance of genetic drift in shaping patterns of adaptive genetic variation in nature is poorly known. Genetic drift should drive partially recessive deleterious mutations to high frequency, and inter‐population crosses may therefore exhibit heterosis (increased fitness relative to intra‐population crosses). Low genetic diversity and greater genetic distance between populations should increase the magnitude of heterosis. Moreover, drift and selection should remove strongly deleterious recessive alleles from individual populations, resulting in reduced inbreeding depression. To estimate heterosis, we crossed 90 independent line pairs of
Arabidopsis thaliana from 15 pairs of natural populations sampled across Fennoscandia and crossed an additional 41 line pairs from a subset of four of these populations to estimate inbreeding depression. We measured lifetime fitness of crosses relative to parents in a large outdoor common garden (8,448 plants in total) in central Sweden. To examine the effects of genetic diversity and genetic distance on heterosis, we genotyped parental lines for 869 SNPs. Overall, genetic variation within populations was low (median expected heterozygosity = 0.02), and genetic differentiation was high (medianF ST = 0.82). Crosses between 10 of 15 population pairs exhibited significant heterosis, with magnitudes of heterosis as high as 117%. We found no significant inbreeding depression, suggesting that the observed heterosis is due to fixation of mildly deleterious alleles within populations. Widespread and substantial heterosis indicates an important role for drift in shaping genetic variation, but there was no significant relationship between fitness of crosses relative to parents and genetic diversity or genetic distance between populations.