ORCID Profile
0000-0002-4302-3048
Current Organisations
University of Aberdeen
,
Western Australian Museum
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Publisher: Wiley
Date: 06-10-2019
DOI: 10.1111/ZSC.12374
Publisher: Springer Science and Business Media LLC
Date: 18-09-2019
DOI: 10.1186/S12862-019-1499-8
Abstract: Marine invertebrates are abundant and erse on the continental shelf in Antarctica, but little is known about their parasitic counterparts. Endoparasites are especially understudied because they often possess highly modified body plans that pose problems for their identification. Asterophila , a genus of endoparasitic gastropod in the family Eulimidae, forms cysts in the arms and central discs of asteroid sea stars. There are currently four known species in this genus, one of which has been described from the Antarctic Peninsula ( A. perknasteri ). This study employs molecular and morphological data to investigate the ersity of Asterophila in Antarctica and explore cophylogenetic patterns between host and parasite. A maximum-likelihood phylogeny of Asterophila and subsequent species-delimitation analysis uncovered nine well-supported putative species, eight of which are new to science. Most Asterophila species were found on a single host species, but four species were found on multiple hosts from one or two closely related genera, showing phylogenetic conservatism of host use. Both distance-based and event-based cophylogenetic analyses uncovered a strong signal of coevolution in this system, but most associations were explained by non-cospeciation events. The prevalence of duplication and host-switching events in Asterophila and its asteroid hosts suggests that synchronous evolution may be rare even in obligate endoparasitic systems. The apparent restricted distribution of Asterophila from around the Scotia Arc may be an artefact of concentrated s ling in the area and a low obvious prevalence of infection. Given the richness of parasites on a global scale, their role in promoting host ersification, and the threat of their loss through coextinction, future work should continue to investigate parasite ersity and coevolution in vulnerable ecosystems.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.YMPEV.2018.02.008
Abstract: Chromodoris is a genus of colourful nudibranchs that feed on sponges and is found across the Indo-Pacific. While this was once the most erse chromodorid genus, recent work has shown that the genus should be restricted to a monophyletic lineage that contains only 22 species, all of which exhibit black pigmentation and planar spawning behaviour. Earlier phylogenies of this group are poorly resolved and thus additional work is needed to clarify species boundaries within Chromodoris. This study presents a maximum-likelihood phylogeny based on mitochondrial loci (COI, 16S) for 345 Chromodoris specimens, including data from 323 new specimens and 22 from GenBank, from across the Indo-Pacific. Species hypotheses and phylogenetic analysis uncovered 39 taxa in total containing 18 undescribed species, with only five of 39 taxa showing stable colour patterns and distinct morphotypes. This study also presents the first evidence for regional mimicry in this genus, with C. colemani and C. joshi displaying geographically-based variation in colour patterns which appear to match locally abundant congenerics, highlighting the flexibility of these colour patterns in Chromodoris nudibranchs. The current phylogeny contains short branch lengths, polytomies and poor support at interior nodes, which is indicative of a recent radiation. As such, future work will employ a transcriptome-based exon capture approach for resolving the phylogeny of this group. In all, this study included 21 of the 22 described species in the Chromodoris sensu stricto group with broad s ling coverage from across the Indo-Pacific, constituting the most comprehensive s ling of this group to date. This work highlights several cases of undocumented ersity, ultimately expanding our knowledge of species boundaries in this group, while also demonstrating the limitations of colour patterns for species identification in this genus.
Publisher: Pensoft Publishers
Date: 30-08-2015
DOI: 10.3897/BDJ.3.E6313
Publisher: Wiley
Date: 12-08-2021
DOI: 10.1111/MEC.16033
Abstract: The post‐glacial colonization of Gander Lake in Newfoundland, Canada, by Arctic Charr ( Salvelinus alpinus) provides the opportunity to study the genomic basis of adaptation to extreme deep‐water environments. Colonization of deep‐water ( m) habitats often requires extensive adaptation to cope with novel environmental challenges from high hydrostatic pressure, low temperature, and low light, but the genomic mechanisms underlying evolution in these environments are rarely known. Here, we compare genomic ergence between a deep‐water morph adapted to depths of up to 288 m and a larger, piscivorous pelagic morph occupying shallower depths. Using both a SNP array and resequencing of whole nuclear and mitochondrial genomes, we find clear genetic ergence ( F ST = 0.11–0.15) between deep and shallow water morphs, despite an absence of morph ergence across the mitochondrial genome. Outlier analyses identified many erged genomic regions containing genes enriched for processes such as gene expression and DNA repair, cardiac function, and membrane transport. Detection of putative copy number variants (CNVs) uncovered 385 genes with CNVs distinct to piscivorous morphs, and 275 genes with CNVs distinct to deep‐water morphs, enriched for processes associated with synapse assembly. Demographic analyses identified evidence for recent and local morph ergence, and ongoing reductions in ersity consistent with postglacial colonization. Together, these results show that Arctic Charr morph ergence has occurred through genome‐wide differentiation and elevated ergence of genes underlying multiple cellular and physiological processes, providing insight into the genomic basis of adaptation in a deep‐water habitat following postglacial recolonization.
Publisher: Oxford University Press (OUP)
Date: 06-12-2015
Publisher: Wiley
Date: 03-04-2023
DOI: 10.1111/MEC.16913
Abstract: Polymorphic species are useful models for investigating the evolutionary processes driving ersification. Such processes include colonization history as well as contemporary selection, gene flow, and genetic drift, which can vary between intraspecific morphs as a function of their distinct life histories. The interactive and relative influence of such evolutionary processes on morph differentiation critically informs morph‐specific management decisions and our understanding of incipient speciation. We therefore investigated how geographic distance, environmental conditions, and colonization history interacted with morph migratory capacity in the highly polymorphic fish species, Arctic Charr ( Salvelinus alpinus ). Using an 87 k SNP chip we genetically characterized recently evolved anadromous, resident, and landlocked charr collected from 45 locations across a secondary contact zone of three charr glacial lineages in eastern Canada. A strong pattern of isolation by distance across all populations suggested geographic distance principally shaped genetic structure. Landlocked populations had lower genetic ersities and higher genetic differentiation than anadromous populations. However, effective population size was generally temporally stable in landlocked populations in comparison to anadromous populations. Genetic ersity positively correlated with latitude, potentially indicating southern anadromous populations' vulnerability to climate change and greater introgression between the Arctic and Atlantic glacial lineages in northern Labrador. Local adaptation was suggested by the observation of several environmental variables strongly associating with functionally relevant outlier genes including a region on chromosome AC21 potentially associated with anadromy. Our results demonstrate that gene flow, colonization history, and local adaptation uniquely interact to influence the genetic variation and evolutionary trajectory of populations.
Publisher: Inter-Research Science Center
Date: 29-09-2015
DOI: 10.3354/MEPS11424
Publisher: Wiley
Date: 17-09-2020
DOI: 10.1002/ECE3.6727
Abstract: Phylogenetic inference and species delimitation can be challenging in taxonomic groups that have recently radiated and where introgression produces conflicting gene trees, especially when species delimitation has traditionally relied on mitochondrial data and color pattern. Chromodoris , a genus of colorful and toxic nudibranch in the Indo‐Pacific, has been shown to have extraordinary cryptic ersity and mimicry, and has recently radiated, ultimately complicating species delimitation. In these cases, additional genome‐wide data can help improve phylogenetic resolution and provide important insights about evolutionary history. Here, we employ a transcriptome‐based exon capture approach to resolve Chromodoris phylogeny with data from 2,925 exons and 1,630 genes, derived from 15 nudibranch transcriptomes. We show that some previously identified mimics instead show mitonuclear discordance, likely deriving from introgression or mitochondrial capture, but we confirm one “pure” mimic in Western Australia. Sister–species relationships and species‐level entities were recovered with high support in both concatenated maximum likelihood (ML) and summary coalescent phylogenies, but the ML topologies were highly variable while the coalescent topologies were consistent across datasets. Our work also demonstrates the broad phylogenetic utility of 149 genes that were previously identified from eupulmonate gastropods. This study is one of the first to (a) demonstrate the efficacy of exon capture for recovering relationships among recently radiated invertebrate taxa, (b) employ genome‐wide nuclear markers to test mimicry hypotheses in nudibranchs and (c) provide evidence for introgression and mitochondrial capture in nudibranchs.
Publisher: Frontiers Media SA
Date: 22-06-2022
DOI: 10.3389/FGENE.2022.886494
Abstract: A key component of the global blue economy strategy is the sustainable extraction of marine resources and conservation of marine environments through networks of marine protected areas (MPAs). Connectivity and representativity are essential factors that underlie successful implementation of MPA networks, which can safeguard biological ersity and ecosystem function, and ultimately support the blue economy strategy by balancing ocean use with conservation. New “big data” omics approaches, including genomics and transcriptomics, are becoming essential tools for the development and maintenance of MPA networks. Current molecular omics techniques, including population-scale genome sequencing, have direct applications for assessing population connectivity and for evaluating how genetic variation is represented within and among MPAs. Effective baseline characterization and long-term, scalable, and comprehensive monitoring are essential for successful MPA management, and omics approaches hold great promise to characterize the full range of marine life, spanning the microbiome to megafauna across a range of environmental conditions (shallow sea to the deep ocean). Omics tools, such as eDNA metabarcoding can provide a cost-effective basis for bio ersity monitoring in large and remote conservation areas. Here we provide an overview of current omics applications for conservation planning and monitoring, with a focus on metabarcoding, metagenomics, and population genomics. Emerging approaches, including whole-genome sequencing, characterization of genomic architecture, epigenomics, and genomic vulnerability to climate change are also reviewed. We demonstrate that the operationalization of omics tools can enhance the design, monitoring, and management of MPAs and thus will play an important role in a modern and comprehensive blue economy strategy.
Publisher: Wiley
Date: 08-11-2021
Abstract: Predicting how species will respond to future climate change is of central importance in the midst of the global bio ersity crisis, and recent work has demonstrated the utility of population genomics for improving these predictions. Here, we suggest a broadening of the approach to include other types of genomic variants that play an important role in adaptation, like structural (e.g. copy number variants) and epigenetic variants (e.g. DNA methylation). These data could provide additional power for forecasting response, especially in weakly structured or panmictic species. Incorporating structural and epigenetic variation into estimates of climate change vulnerability, or maladaptation, may not only improve prediction power but also provide insight into the molecular mechanisms underpinning species' response to climate change.
Publisher: Frontiers Media SA
Date: 10-06-2022
DOI: 10.3389/FMARS.2022.872727
Abstract: Ecosystem-based conservation that includes carbon sinks, alongside a linked carbon credit system, as part of a nature-based solution to combating climate change, could help reduce greenhouse gas levels and therefore the impact of their emissions. Blue carbon habitats and pathways can also facilitate bio ersity retention, aiding sustainable fisheries and island economies. However, robust blue carbon research is often limited at the scale of regional governance and management, lacking both incentives and facilitation of policy-integration. The remote and highly bio erse coastal ecosystems and surrounding continental shelf can be used to better inform long-term ecosystem-based management in the vast South Atlantic Ocean and sub-Antarctic, to synergistically protect both unique bio ersity and inform on the magnitude of nature-based benefits they provide. Understanding key ecosystem information such as their location, extent, and condition of habitat types, will be critical in understanding carbon pathways to sequestration, threats to this, and vulnerability. This paper considers the current status of blue carbon data and information available, and what is still required before blue carbon can be used as a conservation management tool integrated in national Marine Spatial Planning (MSP) initiatives. Our research indicates that the data and information gathered has enabled baselines for a number of different blue carbon ecosystems, and indicated potential threats and vulnerability that need to be managed. However, significant knowledge gaps remain across habitats, such as salt marsh, mudflats and the mesophotic zones, which hinders meaningful progress on the ground where it is needed most.
Publisher: Canadian Science Publishing
Date: 04-2019
Abstract: Global identification and monitoring programs for invasive species aim to reduce imminent impacts to bio ersity, ecosystem services, agriculture, and human health. This study employs a 658 base pair fragment of the cytochrome c oxidase subunit I (COI) gene to identify and categorize clades of the banded grove snail (Cepaea nemoralis (Linnaeus, 1758)) from native (European) and introduced (North American) ranges using a maximum-likelihood phylogeny and haplotype networks. This work corroborates the existence of eight clades within C. nemoralis and further identified three clades that were common to both Europe and North America (A, D, O). Clades A and D were found in eastern Canada, Ontario (Canada), and British Columbia (Canada), whereas clade O was restricted to Ontario, possibly introduced from Poland or central Europe. Haplotype networks suggest clade A was introduced from northern Europe, whereas clade D was introduced from western and central Europe. Networks contained many private haplotypes and a lack of haplotype sharing, suggesting strong genetic structure in this system, possibly resulting from reduced dispersal in this species. This study describes the contemporary distribution of C. nemoralis in Canada and demonstrates the efficacy of DNA barcoding for monitoring the spread of invasive species, warranting its widespread adoption in management policies.
Publisher: Elsevier BV
Date: 11-2014
Publisher: Springer Science and Business Media LLC
Date: 06-12-2019
DOI: 10.1038/S41597-019-0320-2
Abstract: The reliable taxonomic identification of organisms through DNA sequence data requires a well parameterized library of curated reference sequences. However, it is estimated that just 15% of described animal species are represented in public sequence repositories. To begin to address this deficiency, we provide DNA barcodes for 1,500,003 animal specimens collected from 23 terrestrial and aquatic ecozones at sites across Canada, a nation that comprises 7% of the planet’s land surface. In total, 14 phyla, 43 classes, 163 orders, 1123 families, 6186 genera, and 64,264 Barcode Index Numbers (BINs a proxy for species) are represented. Species-level taxonomy was available for 38% of the specimens, but higher proportions were assigned to a genus (69.5%) and a family (99.9%). Voucher specimens and DNA extracts are archived at the Centre for Bio ersity Genomics where they are available for further research. The corresponding sequence and taxonomic data can be accessed through the Barcode of Life Data System, GenBank, the Global Bio ersity Information Facility, and the Global Genome Bio ersity Network Data Portal.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Inter-Research Science Center
Date: 02-09-2021
DOI: 10.3354/MEPS13775
Abstract: Arctic charr Salvelinus alpinus are a commercially and culturally valued species for northern Indigenous peoples. Climate shifts could have important implications for charr and those that rely on them, but studies that evaluate responses to ecosystem change and the spatial scales at which they occur are rare. We compare marine-phase habitat use, long-term diet patterns, and trends in effective population size of Arctic charr from 2 areas (Nain and Saglek) of Nunatsiavut, Labrador, Canada. Tagged charr in both areas frequently occupied estuaries but some also used other habitats that extended to the headland environments outside of their natal fjords. Despite the relatively small distances separating these study areas ( km), we observed differences in habitat use and diet. Northern stocks (including Saglek) were more reliant on invertebrates than southern stocks (e.g. Nain), for which capelin and sand lance were important prey. The use of coastal headlands also varied, with Saglek charr occupying these environments more frequently than those from Nain, which only used these habitats in 1 year of the study. Long-term commercial catches also indicate that the tendency for Nain charr to stay within fjords varies annually and relates to capelin availability. Despite the demonstrated capacity to alter diet and habitat use to changing environmental conditions, notable declines in effective population size were associated with the regime shift of the 1990s in the northwest Atlantic. Collectively, these results demonstrate that behavioral plasticity of Arctic charr may be insufficient to deal with the large environmental perturbations expected to arise from a changing climate.
Publisher: Australian Museum
Date: 13-12-2017
Publisher: Elsevier BV
Date: 07-2023
Publisher: Public Library of Science (PLoS)
Date: 17-04-2014
Publisher: Springer Science and Business Media LLC
Date: 11-01-2021
Publisher: Oxford University Press (OUP)
Date: 08-2020
Abstract: Characterizing the nature of genetic differentiation among in iduals and populations and its distribution across the genome is increasingly important to inform both conservation and management of exploited species. Atlantic Halibut (Hippoglossus hippoglossus) is an ecologically and commercially important fish species, yet knowledge of population structure and genomic ersity in this species remains lacking. Here, we use restriction-site associated DNA sequencing and a chromosome-level genome assembly to identify over 86 000 single nucleotide polymorphisms mapped to 24 chromosome-sized scaffolds, genotyped in 734 in iduals across the Northwest Atlantic. We describe subtle but significant genome-wide regional structuring between the Gulf of St. Lawrence and adjacent Atlantic continental shelf. However, the majority of genetic ergence is associated with a large putative chromosomal rearrangement (5.74 megabases) displaying high differentiation and linkage disequilibrium, but no evidence of geographic variation. Demographic reconstructions suggest periods of expansion coinciding with glacial retreat, and more recent declines in Ne. This work highlights the utility of genomic data to identify multiple sources of genetic structure and genomic ersity in commercially exploited marine species.
Publisher: Inter-Research Science Center
Date: 13-02-2020
DOI: 10.3354/AEI00346
Abstract: Genetic interactions (i.e. hybridization) between wild and escaped Atlantic salmon Salmo salar from aquaculture operations have been widely documented, yet the ability to incorporate predictions of risk into aquaculture siting advice has been limited. Here we demonstrate a model-based approach to assessing these potential genetic interactions using a salmon aquaculture expansion scenario in southern Newfoundland as an ex le. We use an eco-genetic in idual-based Atlantic salmon model (IBSEM) parameterized for southern Newfoundland populations, with regional environmental data and field-based estimates of survival, to explore how the proportion of escapees relative to the size of wild populations could potentially influence genetic and demographic changes in wild populations. Our simulations suggest that both demographic decline and genetic change are predicted when the percentage of escapees in a river relative to wild population size is equal to or exceeds 10% annually. The occurrence of escapees in southern Newfoundland rivers under a proposed expansion scenario was predicted using river and site locations and models of dispersal for early and late escapees. Model predictions of escapee dispersal suggest that under the proposed expansion scenario, the number of escapees is expected to increase by 49% and the highest escapee concentrations will shift westward, consistent with the location of proposed expansion (20 rivers total % escapees, max 24%). Our results identify susceptible rivers and potential impacts predicted under the proposed aquaculture expansion scenario and illustrate how model-based predictions of both escapee dispersal and genetic impacts can be used to inform both aquaculture management decisions and wild salmon conservation.
Publisher: Wiley
Date: 20-02-2020
DOI: 10.1111/EVA.12922
Publisher: Wiley
Date: 03-10-2020
DOI: 10.1111/MEC.15634
Publisher: Public Library of Science (PLoS)
Date: 21-11-2016
Publisher: Springer Science and Business Media LLC
Date: 17-03-2021
Location: United Kingdom of Great Britain and Northern Ireland
Location: Canada
No related grants have been discovered for Kara Layton.