79 research outputs found
Evolutionary factors affecting Lactate dehydrogenase A and B variation in the Daphnia pulex species complex
Background: Evidence for historical, demographic and selective factors affecting enzyme evolution can be
obtained by examining nucleotide sequence variation in candidate genes such as Lactate dehydrogenase (Ldh). Two
closely related Daphnia species can be distinguished by their electrophoretic Ldh genotype and habitat. Daphnia
pulex populations are fixed for the S allele and inhabit temporary ponds, while D. pulicaria populations are fixed for
the F allele and inhabit large stratified lakes. One locus is detected in most allozyme surveys, but genome
sequencing has revealed two genes, LdhA and LdhB.
Results: We sequenced both Ldh genes from 70 isolates of these two species from North America to determine if
the association between Ldh genotype and habitat shows evidence for selection, and to elucidate the evolutionary
history of the two genes. We found that alleles in the pond-dwelling D. pulex and in the lake-dwelling D. pulicaria
form distinct groups at both loci, and the substitution of Glutamine (S) for Glutamic acid (F) at amino acid 229
likely causes the electrophoretic mobility shift in the LDHA protein. Nucleotide diversity in both Ldh genes is much
lower in D. pulicaria than in D. pulex. Moreover, the lack of spatial structuring of the variation in both genes over a
wide geographic area is consistent with a recent demographic expansion of lake populations. Neutrality tests
indicate that both genes are under purifying selection, but the intensity is much stronger on LdhA.
Conclusions: Although lake-dwelling D. pulicaria hybridizes with the other lineages in the pulex species complex,
it remains distinct ecologically and genetically. This ecological divergence, coupled with the intensity of purifying
selection on LdhA and the strong association between its genotype and habitat, suggests that experimental
studies would be useful to determine if variation in molecular function provides evidence that LDHA variants are
adaptive
Cost-effective scat-detection dogs: unleashing a powerful new tool for international mammalian conservation biology
Recently, detection dogs have been utilized to collect fecal samples from cryptic and rare mammals. Despite the great promise of this technique for conservation biology, its broader application has been limited by the high cost (tens to hundreds of thousands of dollars) and logistical challenges of employing a scat-detection dog team while conducting international, collaborative research. Through an international collaboration of primatologists and the Chinese Ministry of Public Security, we trained and used a detection dog to find scat from three species of unhabituated, free-ranging primates, for less than $3,000. We collected 137 non-human primate fecal samples that we confirmed by sequencing taxonomically informative genetic markers. Our detection dog team had a 92% accuracy rate, significantly outperforming our human-only team. Our results demonstrate that detection dogs can locate fecal samples from unhabituated primates with variable diets, locomotion, and grouping patterns, despite challenging field conditions. We provide a model for in-country training, while also building local capacity for conservation and genetic monitoring. Unlike previous efforts, our approach will allow for the wide adoption of scat-detection dogs in international conservation biology
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Horizon scan of conservation issues for inland waters in Canada
Horizon scanning is a systematic approach increasingly used to explore emerging trends, issues, opportunities, and threats in conservation. We present the results from one such exercise aimed at identifying emerging issues that could have important scientific, social, technological, and managerial implications for the conservation of inland waters in Canada in the proximate future. We recognized six opportunities and nine challenges, for which we provide research implications and policy options, such that scientists, policy makers, and the Canadian society as a whole can prepare for a potential growth in each of the topic areas we identified. The issues spanned a broad range of topics, from recognizing the opportunities and challenges of community-enabled science and the need to consider the legal rights of nature, to the likely increase of pharmaceuticals in wastewater due to an aging population. These issues represent a first baseline that could help decision makers identify and prioritize efforts while simultaneously stimulate new research avenues. We hope our horizon scan will pave the way for similar exercises related to the conservation of biodiversity in Canada.This project was organized with the support of the Groupe de recherche Interuniversitaire en Limnologie, and the Liber Ero Chair at McGill University. IGE, RB, MC, SJC, AH acknowledge support from the Canada Research Chairs program, and KG, CB and NSG acknowledge funding from the NSERC-funded LakePulse Network. WJS is funded by Arcadia. The authors also thank Sara Pancheri for developing Figure 1a. Finally, we would like to thank Amanda K. Winegardner, who was an active participant in the workshop and provided substantial edits and comments of the manuscript
Coexisting Cyclic Parthenogens Comprise a Holocene Species Flock in Eubosmina
Background: Mixed breeding systems with extended clonal phases and weak sexual recruitment are widespread in nature but often thought to impede the formation of discrete evolutionary clusters. Thus, cyclic parthenogens, such as cladocerans and rotifers, could be predisposed to ‘‘species problems’ ’ and a lack of discrete species. However, species flocks have been proposed for one cladoceran group, Eubosmina, where putative species are sympatric, and there is a detailed paleolimnological record indicating a Holocene age. These factors make the Eubosmina system suitable for testing the hypotheses that extended clonal phases and weak sexual recruitment inhibit speciation. Although common garden experiments have revealed a genetic component to the morphotypic variation, the evolutionary significance of the morphotypes remains controversial. Methodology/Principal Findings: In the present study, we tested the hypothesis of a single polymorphic species (i.e., mixing occurs but selection maintains genes for morphology) in four northern European lakes where the morphotypes coexist. Our evidence is based on nuclear DNA sequence, mitochondrial DNA sequence, and morphometric analysis of coexisting morphotypes. We found significant genetic differentiation, genealogical exclusivity, and morphometric differentiation for coexisting morphotypes. Conclusions: We conclude that the studied morphotypes represent a group of young species undergoing speciation wit
Exploring the Relationship between Semantics and Space
The asymmetric distribution of human spatial attention has been repeatedly documented in both patients and healthy controls. Biases in the distribution of attention and/or in the mental representation of space may also affect some aspects of language processing. We investigated whether biases in attention and/or mental representation of space affect semantic representations. In particular, we investigated whether semantic judgments could be modulated by the location in space where the semantic information was presented and the role of the left and right parietal cortices in this task. Healthy subjects were presented with three pictures arranged horizontally (one middle and two outer pictures) of items belonging to the same semantic category. Subjects were asked to indicate the spatial position in which the semantic distance between the outer and middle pictures was smaller. Subjects systematically overestimated the semantic distance of items presented in the right side of space. We explored the neural correlates underpinning this bias using rTMS over the left and right parietal cortex. rTMS of the left parietal cortex selectively reduced this rightward bias. Our findings suggest the existence of an attentional and/or mental representational bias in semantic judgments, similar to that observed for the processing of space and numbers. Spatial manipulation of semantic material results in the activation of specialised attentional resources located in the left hemisphere
Population genomics of marine zooplankton
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Bucklin, Ann et al. "Population Genomics of Marine Zooplankton." Population Genomics: Marine Organisms. Ed. Om P. Rajora and Marjorie Oleksiak. Springer, 2018. doi:10.1007/13836_2017_9.The exceptionally large population size and cosmopolitan biogeographic distribution that
distinguish many – but not all – marine zooplankton species generate similarly exceptional patterns of
population genetic and genomic diversity and structure. The phylogenetic diversity of zooplankton has
slowed the application of population genomic approaches, due to lack of genomic resources for closelyrelated
species and diversity of genomic architecture, including highly-replicated genomes of many
crustaceans. Use of numerous genomic markers, especially single nucleotide polymorphisms (SNPs), is
transforming our ability to analyze population genetics and connectivity of marine zooplankton, and
providing new understanding and different answers than earlier analyses, which typically used
mitochondrial DNA and microsatellite markers. Population genomic approaches have confirmed that,
despite high dispersal potential, many zooplankton species exhibit genetic structuring among geographic
populations, especially at large ocean-basin scales, and have revealed patterns and pathways of population
connectivity that do not always track ocean circulation. Genomic and transcriptomic resources are
critically needed to allow further examination of micro-evolution and local adaptation, including
identification of genes that show evidence of selection. These new tools will also enable further
examination of the significance of small-scale genetic heterogeneity of marine zooplankton, to
discriminate genetic “noise” in large and patchy populations from local adaptation to environmental
conditions and change.Support was provided by the
US National Science Foundation to AB and RJO (PLR-1044982) and to RJO (MCB-1613856); support to
IS and MC was provided by Nord University (Norway)
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