A decade of seascape genetics: contributions to basic and applied marine connectivity

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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)

Ecological dispersal barrier across the equatorial Atlantic in a migratory planktonic copepod

Resolving the large-scale genetic structure of plankton populations is important to understanding their responses to climate change. However, few studies have reported on the presence and geographic extent of genetically distinct populations of marine zooplankton at ocean-basin scales. Using mitochondrial sequence data (mtCOI, 718 animals) from 18 sites across a basin-scale Atlantic transect (39°N–40°S), we show that populations of the dominant migratory copepod, Pleuromamma xiphias, are genetically subdivided across subtropical and tropical waters (global FST = 0.15, global ΦST = 0.21, both P < 0.00001), with a major genetic break observed in the equatorial Atlantic (between gyre FCT and ΦCT = 0.23, P < 0.005). This equatorial region of strong genetic transition coincides with an area of low abundance for the species. Transitional regions between the subtropical gyres and the equatorial province also harbor a distinct mitochondrial clade (clade 2), have higher haplotype and nucleotide diversities relative to the northern and/or southern subtropical gyres (e.g., mean h = 0.831 EQ, 0.742 North, 0.594 South, F2,11 = 20.53, P < 0.001), and are genetically differentiated from the majority of sites in the central gyre and temperate zones of the same hemisphere (significant pairwise ΦST 0.038–0.267, 79% significant). Our observations support the hypothesis that regions of low abundance within species mark areas of suboptimal habitat that serve as dispersal barriers for marine plankton, and we suggest that this may be a dominant mechanism driving the large-scale genetic structure of zooplankton species. Our results also demonstrate the potential importance of the Atlantic equatorial province as a region of evolutionary novelty for the holoplankton

Comparative phylogeography of the ocean planet

Understanding how geography, oceanography, and climate have ultimately shaped marine biodiversity requires aligning the distributions of genetic diversity across multiple taxa. Here, we examine phylogeographic partitions in the sea against a backdrop of biogeographic provinces defined by taxonomy, endemism, and species composition. The taxonomic identities used to define biogeographic provinces are routinely accompanied by diagnostic genetic differences between sister species, indicating interspecific concordance between biogeography and phylogeography. In cases where individual species are distributed across two or more biogeographic provinces, shifts in genotype frequencies often align with biogeographic boundaries, providing intraspecific concordance between biogeography and phylogeography. Here, we provide examples of comparative phylogeography from (i) tropical seas that host the highest marine biodiversity, (ii) temperate seas with high productivity but volatile coastlines, (iii) migratory marine fauna, and (iv) plankton that are the most abundant eukaryotes on earth. Tropical and temperate zones both show impacts of glacial cycles, the former primarily through changing sea levels, and the latter through coastal habitat disruption. The general concordance between biogeography and phylogeography indicates that the population-level genetic divergences observed between provinces are a starting point for macroevolutionary divergences between species. However, isolation between provinces does not account for all marine biodiversity; the remainder arises through alternative pathways, such as ecological speciation and parapatric (semiisolated) divergences within provinces and biodiversity hotspots

Global trends and biases in biodiversity conservation research

Efforts to conserve biodiversity have been hampered by long-standing biases, including a disproportionate focus on particular taxa and ecosystems with minimal attention to underlying genetic diversity. We assessed whether these biases have persisted over the past four decades by analyzing trends in 17,502 research articles published in four top conservation-focused journals. Overall, we found that historical biases in conservation biology research remain entrenched. Despite increasing numbers of conservation articles published each decade from 1980 to 2020, research effort has increasingly focused on the same suite of taxa. Surprisingly, some of the most-studied species in these conservation articles had low conservation risk, including several domesticated animals. Animals and terrestrial ecosystems are consistently over-represented while plants, fungi, and freshwater ecosystems remain under-represented. Strategically funding investigations of understudied species and ecosystems will ensure more effective conservation effort across multiple levels of biodiversity, alleviate impediments to biodiversity targets, and ultimately prevent further extinctions. [Display omitted] •Biases in conservation research have not changed over time•Conservation research increasingly focuses on the same suite of species•Conservation status of a species does not seem to predict research attention•Targeted funding of understudied systems is necessary to even out research imbalance While efforts to conserve biodiversity are increasing, research and conservation efforts are unequally allocated across different scales of biodiversity, with within-species diversity receiving the least overall attention. One potential solution is to realign funding priorities to promote efforts across different scales, from genetic to species to ecosystem. With limited funding, prioritization approaches seek to maximize impact by returning to ongoing conservation efforts or focusing on high-profile species. However, these approaches reinforce biases against more equitable allocation because a lack of knowledge about understudied groups can be seen as detrimental to conservation success and prohibitively expensive. This study shows that these biases in conservation research are long standing and still ongoing, which will ultimately lead to an uneven loss of biodiversity. Deliberate funding and targeted efforts are needed to investigate both understudied species and ecosystems. Conservation biology research seems biased toward popular species and ecosystems, with seemingly little attention paid to within-species (genetic) diversity. By looking through thousands of conservation-focused research articles, we found that these biases have been notably consistent over the last four decades. We saw that some of the most-studied species have low conservation risk, and some are domesticated animals. Animals and terrestrial ecosystems are consistently over-represented while plants, fungi, and freshwater ecosystems remain under-represented

Three-year monitoring of genetic diversity reveals a micro-connectivity pattern and local recruitment in the broadcast marine species Paracentrotus lividus

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