Evidence Of Genetic Structure Research Articles

Genetic association and causal effects between inflammatory bowel disease and conjunctivitis.

Inflammatory bowel disease (IBD) is often clinically associated with conjunctivitis, which may result from genetic associations and causal effects. Genetic correlations were investigated through the genome-wide association study (GWAS) data on IBD and conjunctivitis using the linkage disequilibrium score regression (LDSC) and heritability estimated in summary statistics (HESS). The causal effect analysis was performed using four methods of Mendelian randomization (MR) and the genetic risk loci common to both diseases were identified by the statistical method of conditional/conjoint false discovery rate (cond/conjFDR), followed by genetic overlap analysis. Finally, a multi-trait GWAS analysis (MTAG) was performed to validate the identified shared loci. IBD (including CD and UC) and conjunctivitis showed a significant overall correlation at the genomic level; however, the local correlation of IBD and CD with conjunctivitis was significant and limited to chromosome 11. MR analysis suggested a significant positive and non-significant negative correlation between IBD (including CD and UC) and conjunctivitis. The conjFDR analysis confirmed the genetic overlap between the two diseases. Additionally, MTAG was employed to identify and validate multiple genetic risk loci. The present study provides evidence of genetic structure and causal effects for the co-morbidity between IBD (both CD and UC) and conjunctivitis, expanding the epidemiologic understanding of the two diseases.

Comparing the effect of larval dispersal strategies on morphological versus genetic differentiation in two neotropical fiddler crabs

AbstractThe dispersal mode of estuarine invertebrates has a strong effect on genetic variability and phenotypic expression, potentially maintaining gene flow among widely separated populations or limiting connectivity among close ones. Understanding the dispersal strategies effects can support adequate strategies for environment management and understand the evolutionary history of the studied species. A comparative study on the effect of larval dispersal strategies (export vs retention) along the overall geographic distribution ranges of adult populations of two co‐distributed fiddler crab species was performed. Geometric morphometric techniques were used to evaluate morphological differentiation in the shape of the carapace and major cheliped propodus in 10 populations of Minuca mordax and five populations of Leptuca leptodactyla. Potential genetic differentiation was assessed using DNA sequence data from up to 170 fiddler crab specimens, corresponding to the mitochondrial gene cytochrome c oxidase subunit 1 (COX1). Patterns of genetic and morphological characteristics diverged among populations of both species. In terms of morphology, populations of both species showed intraspecific variation in the shape of the carapace and, to a lesser extent, in the major cheliped propodus. This observed intraspecific variation followed a clear geographic pattern of morphometric differentiation, in which the geographic origin is associated with a phenotypic response to the environmental diversity along the extended Brazilian coast. In contrast, there are shared haplotypes in populations separated by more than 4000 km, but with significant ΦST values among most populations of L. leptodactyla and M. mordax, suggesting a moderate to high level of gene flow. Therefore, it can be concluded that the split of the Central South Equatorial Current has not acted as an efficient long‐term barrier to the dispersal of larvae in both species. In M. mordax, a slight limitation of genetic exchange can be observed between the southernmost populations and the remaining ones. This first evidence of genetic structuring within this widely distributed species is consistent with its documented strategy to retain larvae in the estuarine environments. However, occasional transport of larvae to more open coastal waters seems to maintain stepwise gene flow between neighboring populations. Overall, our results still provide evidence of more pronounced genetic homogeneity in a species with a larval export strategy (L. leptodactyla) compared to a species with a larval retention strategy (M. mordax). This suggests that larval dispersal strategies, coupled with the microhabitat in which the respective species occur, have a noticeable effect on the degree of gene flow. Most likely, these biological aspects are further influenced by the estuarine and coastline geomorphology.

Genetic Diversity and Population Connectivity of the Greenblotch Parrotfish (Scarus quoyi Valenciennes, 1840) within Southern Mindanao Inferred from Mitochondrial 16S rRNA

A genetic assessment was done on the greenblotch parrotfish (Scarus quoyi Valenciennes, 1840) in three bays within southern Mindanao, Philippines. Mitochondrial 16S rRNA recovered 12 haplotypes, one of which was dominant in all sites. Despite the reported phenotypic variation from previous assessments, there was neither evidence of genetic structure (global Φst = 0.012, p = 0.13) nor isolation by distance (r = 0.05, p = 0.50). Genetic diversity was also low (Hglobal = 0.472; πglobal = 0.13%), with ~ 77% of haplotype diversity accounted for with just 69 samples. While connectivity suggests continuous larval exchange within southern Mindanao owing to the species’ high dispersal potential, low genetic diversity implies reduced effective population size, probably due to recent bottlenecks (e.g. overfishing, habitat destruction). Although this study provides baseline genetic information on the local population, inferences are considerably limited by the genetic marker used and the spatial scale under investigation. A thorough understanding of the population will be possible if the entire habitat range of the species is assessed using markers with high resolving power, such as the hypervariable mitochondrial control region, microsatellites, or genome-wide single nucleotide polymorphisms (SNPs).

The Lonely Life of a Champion Tree, Aesculus glabra

Seedlings derived from two Ohio buckeyes (Aesculus glabra Willd.) trees, the National Champion growing in Illinois, USA, and the Ohio State Champion were sampled. The National Champion grows at the northern limits of the species’ native range. The Ohio State Champion grows in Huron County, Ohio, well within the eastern range of the species. We also sampled 40 adult trees growing in Ohio and Illinois. All trees were genotyped at six microsatellite loci. We found that 42 of the 44 sampled seedlings (95%) from the National Champion tree, collected over two seasons, exhibited only maternal alleles at all six microsatellite loci, indicating they were produced by self-fertilization. In contrast, all seedlings from the Ohio state champion tree (N = 48) exhibited non-maternal alleles, indicating they were produced by outcrossing. Our results suggest that when outcross pollen is not available, A. glabra will self-fertilize, but does so rarely or never when outcross pollen is available. Seed germination and early survival were similar for progeny of both champions, but seedlings from the National Champion show lower growth rates and higher mortality during a spring frost, possibly due to inbreeding depression. There was little evidence for genetic structure between trees sampled in Ohio and Illinois.

Global phylogeography of the flood mosquito, Aedes vexans (Diptera: Culicidae), from mitochondrial DNA

This contribution endeavored to investigate the genetic structure and gene flow of the flood mosquito, Aedes vexans (Meigen, 1830). Using partial sequences of the mitochondrial COI gene, available from BOLD Systems and GenBank, the Haplotypic (Hd) and nucleotide (π) gene diversity, genetic structuring and gene flow of A. vexans at the global, continental, and country levels were calculated. In total, 1,184 sequences were obtained, distributed among America (88.60%; represented by EUA and Canada), Europe (7.35%), Asia (3.89%), and Africa (0.17%). From these, 395 haplotypes (H) without presence of pseudogenes (NUMTs) were detected. The cluster analyses grouped the haplotypes into six clades. Clade I includes haplotypes from countries in America and Europe, while clades II and III include haplotypes exclusively from Asia and Europe; clade IV grouped only one haplotype from Africa and clade V grouped haplotypes from America and Africa. The global Hd and π were 0.92 and 0.01, respectively. In addition, there is evidence of genetic structuring among continents (7.07%), countries (1.62%), and within countries (91.30%; FST = 0.08, p < 0.05) and no isolation by distance was detected (r = 0.003, p > 0.05). The genetic diversity of A. vexans was found to be greater in North America than in other continents. Although this provisional conclusion might be influenced by a sample bias, since 88.60% of the sequences are from America, is also plausible to consider that America corresponds to the ancestral distribution area of the flood mosquito. This hypothesis needs further testing, using a more comprehensive sample from other continents. Additionally, the six clusters found and their geographical distribution do not support previous proposals of splitting the genus into three subspecies confined to certain geographical areas.

Microsatellites reveal that genetic mixing commonly occurs between invasive fall armyworm populations in Africa

Understanding the population structure and movements of the invasive fall armyworm (FAW, Spodoptera frugiperda) is important as it can help mitigate crop damage, and highlight areas at risk of outbreaks or evolving insecticide resistance. Determining population structure in invasive FAW has been a challenge due to genetic mutations affecting the markers traditionally used for strain and haplotype identification; mitochondrial cytochrome oxidase I (COIB) and the Z-chromosome-linked Triosephosphate isomerase (Tpi). Here, we compare the results from COIB and Tpi markers with highly variable repeat regions (microsatellites) to improve our understanding of FAW population structure in Africa. There was very limited genetic diversity using the COIB marker, whereas using the TpiI4 marker there was greater diversity that showed very little evidence of genetic structuring between FAW populations across Africa. There was greater genetic diversity identified using microsatellites, and this revealed a largely panmictic population of FAW alongside some evidence of genetic structuring between countries. It is hypothesised here that FAW are using long-distance flight and prevailing winds to frequently move throughout Africa leading to population mixing. These approaches combined provide important evidence that genetic mixing between invasive FAW populations may be more common than previously reported.

Evidence of genetic structure in the wide-ranging bearded vulture (Gypaetus barbatus (Linnaeus, 1758))

BackgroundThe bearded vulture is sparsely distributed across a wide geographic range that extends over three continents (Africa, Europe and Asia). Restriction to high-altitude mountainous habitats, low breeding rates, lack of food and a heightened level of persecution have left many local populations severely diminished or extinct. Understanding the genetic connectivity and population structure of this threatened vulture species is critical for accurately assessing their conservation status, and for appropriately managing local populations through captive breeding programmes or translocations. Previous genetic assessments of the species were mainly focused on the European and Asian populations and included limited representation of the geographically isolated southern African population. A single mitochondrial study, which focused on the African populations of the bearded vulture, detected limited genetic differentiation between populations in Ethiopia and southern Africa, with reduced haplotype diversity in the southern Africa population. In this study, we extend the previous genetic assessments of the species by examining the phylogeography and genetic connectivity of global G. barbatus populations using a panel of 14 microsatellite loci.ResultsAnalyses revealed spatially correlated genetic differentiation between regional populations and low levels of gene flow between these population fragments. In contrast to the mitochondrial data, the microsatellite data support the management of genetically different populations as separate entities.ConclusionsLow genetic diversity and geographic isolation are known to adversely affect the evolutionary potential of a species in the long-term. The high inbreeding found in the southern African G. barbatus and, to a lesser extent, the northern African populations highlights the need for conservation programmes to effectively manage populations of this species and maintain extant genetic diversity.

Genomic vulnerability of a dominant seaweed points to future-proofing pathways for Australia's underwater forests.

Globally, critical habitats are in decline, threatening ecological, economic and social values and prompting calls for 'future proofing' efforts that enhance resilience to climate change. Such efforts rely on predicting how neutral and adaptive genomic patterns across a species' distribution will change under future climate scenarios, but data is scant for most species of conservation concern. Here, we use seascape genomics to characterise genetic diversity, structure and gene-environmental associations in a dominant forest-forming seaweed, Phyllospora comosa, along its entire latitudinal (12° latitude), and thermal (~14°C) range. Phyllospora showed high connectivity throughout its central range, with evidence of genetic structure and potential selection associated with sea surface temperatures (SSTs) at its rear and leading edges. Rear and leading-edge populations harboured only half the genetic diversity of central populations. By modelling genetic turnover as a function of SST, we assessed the genomic vulnerability across Phyllospora's distributional range under climate change scenarios. Despite low diversity, range-edge populations were predicted to harbour beneficial adaptations to marginal conditions and overall adaptability of the species may be compromised by their loss. Assisted gene flow from range edge populations may be required to enhance adaptation and increase resilience of central and leading-edge populations under warming oceans. Understanding genomic vulnerability can inform proactive restoration and future-proofing strategies for underwater forests and ensure their persistence in changing oceans.

Phylogeography, population connectivity and demographic history of the Stoplight parrotfish, Sparisoma viride (Teleostei: Labridae), in the Greater Caribbean

Few genetic studies that provide biological, ecological and evolutionary information have been conducted for parrotfishes, including Sparisoma viride, and none has covered the full geographic range of this species. Here, we examine the genetic patterns of the Stoplight parrotfish (S. viride) in the Greater Caribbean and its relationship with the recognized biogeographic provinces in the region. Phylogeographic, population and coalescent analyses were performed to examine the genetic structure and connectivity of S. viride populations throughout its entire range within the Greater Caribbean. Two mitochondrial (control region and coxI) and one nuclear (RHO) markers were used. The Stoplight parrotfish shows high haplotypic diversity (h) and low nucleotide diversity (π) in the control region, and low genetic diversity in coxI and RHO. No evidence of genetic structure was found, indicating a panmictic population throughout the Greater Caribbean with highly symmetrical migration rates among previously defined Caribbean biogeographic provinces. The demographic history estimates indicate events of bottlenecks followed by a population expansion dated at 80,000 years ago (kya) during the Pleistocene epoch. These results suggest that the contrasting environmental conditions that define the Greater Caribbean provinces are not barriers to gene flow for S. viride. The phylogeographic patterns of Stoplight parrotfish could be associated with the biological characteristics of the species (such as extensive pelagic larval duration and use of multiple habitats), historical demographic events and physical conditions of the Greater Caribbean, promoting the genetic homogeneity of the species in the region.

Do the importations of crop products affect the genetic diversity from landraces? A study case in garlic (Allium sativum L.)

The increase in importations of elite garlic (Allium sativum L.) in Brazil to meet the local demand in many cities may affect the cultivation of garlic landraces in small family farming systems by driving to the reduction of the harvested area and genetic diversity. The landraces are fundamental sources of genetic variability and adapted germplasm that could be potentially be implemented in breeding programs. The objective of this study was to evaluate the changes in the patterns of genetic diversity in landraces cultivated in family farming systems after three decades of competitiveness with imported garlic. Three landraces of garlic currently cultivated on family farms in the Picos municipality and immediate regions (7° 04′ 55.5″ S 41° 28′ 04.2″ W) and a landrace collected in the same region in the 1970s, before the increase of imports of garlic in Brazil, were selected for this study. Additionally, six garlic accessions from the Garlic Germplasm Bank from ESALQ/USP (Sao Paulo—Brazil) were selected to parallel the genetic diversity present in landraces with other varieties collected in Brazil, completing a set of ten accessions. A randomized block design was used to evaluate nine agro-morphological traits and rank the landraces according to the economically important agronomic traits. The potential changes in genetic diversity patterns and population structure in these populations were also evaluated at a molecular level using eight microsatellite markers. The agro-morphological evaluation indicates that there is genetic diversity in the garlic populations, and it is structured between Picos landraces and ESALQ/USP accessions. There is also evidence of genetic structure between the landraces and populations of the ESALQ/USP accessions (K = 3) based on a Bayesian clustering approach. The moderate genetic differentiation (FST = 0.09) accessed by the microsatellite markers may be associated with the existence of these two different gene pools: Picos landraces and ESALQ/USP accessions. The results indicate that the reduction in harvested areas in the past decades did not affect most morphological characteristics in the landraces, but there was a reduction in the quality of the bulbs. The garlic landraces cultivated nowadays in Picos municipality present a higher number of cloves per bulb, an undesirable characteristic that may affect its commercial value. However, we demonstrate that even with such reduction in harvested areas due to the lack of competitiveness of landraces, there was no reduction in the molecular genetic diversity in these landraces accessed by the microsatellite markers. These are promising results since there is genetic diversity to implement these landraces in genetic breeding programs.

Local Scale Thermal Environment and Limited Gene Flow Indicates Vulnerability of Warm Edge Populations in a Habitat Forming Macroalga

Species inhabiting warm-edge populations of their distribution are suggested to be at the forefront of global warming due to reduced fitness, limited gene flow and living close to their physiological thermal limits. Determining the scale that governs thermal niche and the functional responses of habitat-forming species to environmental stressors is critical for successful conservation efforts, particularly as coastal ecosystems are impacted by global change. Here, we examine the susceptibility of warm-edge populations to warming, in the habitat-forming macroalga, Hormosira banksii, from south-eastern Australia. We use a quantitative breeding design to quantify intraspecific variation in thermal performance (growth, ontogenic development and photosynthetic efficiency) of different genotypes sourced from sites at the equatorward distributional edge (warm-edge) and those towards the center of its distribution (non-edge). The genetic diversity and structure of H. banksii was also examined using microsatellite markers amongst the same sites. Our results found variable responses in thermal performance for growth and development. Warm-edge germlings grew optimally in lower temperatures tested and had narrower thermal breadth compared to non-edge germlings which grew in higher and more broader temperatures. Warm-edge germlings however, showed greater plasticity to tolerate high light indicated by a greater proportion of energy being dissipated as regulated nonphotochemical quenching (Y(NPQ)) than nonregulated nonphotochemical quenching (Y(NO)). Overall genetic diversity was lower at the warm-edge location with evidence of increased structuring and reduced gene flow in comparison to the non-edge location. Evidence of genetic structuring was not found locally between high and low shore within sites. Together, these data suggest that non-edge populations may be “thermally buffered” from increased temperatures associated with ocean warming. Warm-edge populations of H. banksii, however, may be vulnerable to warming, due to narrower thermal breadth and sensitivity to higher temperatures, with genetic impoverishment through loss of individuals likely to further reduce population viability.

Absence of genetic structure reflects post-glacial history and present-day host use in Mapleleaf (Quadrula quadrula) mussel from Manitoba, Canada

Our study documents and analyzes the absence of genetic diversity and structure of the Mapleleaf (Quadrula quadrula (Rafinesque, 1820)) (Bivalvia: Unionidae) mussel in the Lake Winnipeg, Assiniboine River, and Red River drainages (Manitoba, Canada). Previous studies have revealed patterns of genetic diversity and structure in the Mississippi and Ohio river drainages, as well as in the Laurentian Great Lakes drainage. Genotypes from six variable microsatellite loci showed that the Q. quadrula population in Manitoba was significantly differentiated from the population in the Great Lakes drainage (Ontario, Canada), supporting the existence of two Designatable Units in Canada. Conversely, there was no evidence of genetic structure within the sampled range of Q. quadrula in Manitoba. The lack of genetic structure in Q. quadrula across its distribution in Manitoba reflected its post-glacial history and use of a vagile host and necessitates that efforts should be made to ensure connectivity and maintain gene flow across the region. Given that the evidence suggests that Manitoba Q. quadrula belong to a single genetic population, movement of hatchery-propagated juvenile Q. quadrula, adult Q. quadrula, or glochidia-carrying host catfish sourced from any location in Manitoba could be used to augment declining populations or at-risk locations in Manitoba.

An Inventory of Springsnails (Pyrgulopsis spp.) in and Adjacent to the Spring Mountains, Nevada

Springsnails (genus Pyrgulopsis, hereafter pyrgs) are small freshwater aquatic gastropods that occur in isolated springs in western North America. Pyrgs are species of conservation concern, but patterns of occupancy and speciation are complex. We investigated patterns of occurrence for pyrgs in the Spring Mountains, Clark County, Nevada. We were primarily concerned with identifying springs containing the species P. deaconi, the Spring Mountains pyrg, and P. turbatrix, the southeast Nevada pyrg. We identified species through genetic analysis of the COI-1 mitochondrial region and examined patterns of genetic structure. We located aquatic gastropods in 26 springs and analyzed 420 aquatic gastropods, of which 392 were pyrgs, the remainder representing an unknown species of Physa. Of the 26 springs, 25 contained pyrgs and 5 contained Physa sp. For pyrgs, at COI-1 we identified a total of 29 haplotypes that formed 6 distinct monophyletic groups. Five of the 6 groups were consistent with pyrgs previously identified: P. bacchus, P. deaconi, P. fausta, P. turbatrix, and an unknown species which had been identified previously in the Grapevine Springs. The sixth group, found in 2 springs, does not match any reference specimen and is genetically divergent from the other 5 groups. It is most closely related to P. micrococcus. Prior to this study, P. bacchus had not been located in the Spring Mountains. Both P. deaconi and P. turbatrix were located in multiple springs on both the east and west sides of the Spring Mountains, even though the Las Vegas Valley (east) and Pahrump Valley (west) are hydrologically distinct. At the scale of the hydrologic basin, genetic structure was not discernable; haplotype divergence did not align with basin boundaries and the most common haplotype for P. turbatrix occurred on both the east and west sides of the Spring Mountains. While there was little evidence for genetic structuring at the hydrologic-basin level, there was good evidence for structuring at the level of the individual spring. All told, 79% (23/29) of pyrg haplotypes were unique to specific springs, suggesting that pyrg diversity primarily occurs at the level of the individual spring.

Effects of low-density urbanization on genetic structure in the Song Sparrow.

Urbanization fragments landscapes and can impede the movement of organisms through their environment, which can decrease population connectivity. Reduction in connectivity influences gene flow and allele frequencies, and can lead to a reduction in genetic diversity and the fixation of certain alleles, with potential negative effects for populations. Previous studies have detected effects of urbanization on genetic diversity and structure in terrestrial animals living in landscapes that vary in their degree of urbanization, even over very short distances. We investigated the effects of low-intensity urbanization on genetic diversity and genetic structure in Song Sparrows (Melospiza melodia). We captured 208 Song Sparrows at seven sites along a gradient of urbanization in and around Blacksburg, VA, USA, then genotyped them using a panel of fifteen polymorphic microsatellite loci. We found that genetic diversity was comparable among the seven study sites, and there was no evidence of genetic structuring among sites. These findings suggest that over a gradient of urbanization characterized by low density urban development, Song Sparrows likely exist in a single panmictic population.

Genetic diversity and morphological variation in African boxthorn (Lycium ferocissimum) – Characterising the target weed for biological control

Lycium ferocissimum (African boxthorn) is a Weed of National Significance in Australia. Biological control may have potential to manage this weed, but taxonomic uncertainty needs to be addressed first to facilitate searches for potential agents. We sampled putative L. ferocissimum (i.e. tentatively identified morphologically in the field) across its native range in South Africa and introduced range in Australia. Morphometric and genetic analyses were conducted to confirm the species identity of these samples, and to assess morphological and genetic variation across both ranges. All samples collected in Australia were confirmed as L. ferocissimum, with no evidence of hybridisation with any other Lycium species. Nuclear and chloroplast genetic diversity within L. ferocissimum across both South Africa and Australia was low, with no evidence of genetic structure. One of the two common chloroplast haplotypes found across Australia was found at only two sites in South Africa, both near Cape Town, suggesting that the Australian lineage may have originated from this region. Ten samples from South Africa putatively identified in the field as L. ferocissimum were genetically characterised as different (unidentified) Lycium species. Our morphometric analyses across different Lycium species in South Africa did not identify any leaf or floral characteristics unique to L. ferocissimum, and thus morphological identification of the latter species in its native range may remain problematic. To ensure the correct Lycium species is surveyed for candidate biological control agents we suggest that individuals should be permanently tagged and putative morphological determinations supplemented with genetic analyses to confirm species identity.

Population structure undetectable using genetic markers in Mangrove Jack Lutjanus argentimaculatus from its cool-water range limit in eastern Australia

Failure to consider genetic structure in fish populations when collecting aquaculture broodstock can negatively affect fitness, and hence conservation and management goals. Here we used mitochondrial DNA from the 5’ end of the control region (D-loop) and four microsatellite markers to evaluate population genetic structure in the Mangrove Jack Lutjanus argentimaculatus with a view to guiding broodstock collection at the southern extremity of its east Australian range. There was no evidence of genetic structure within the entire tropical, subtropical and temperate east Australian distribution of L. argentimaculatus. Although this species may exhibit clinal morphological and life-history variation at its southern range limit, we did not detect wide- or fine-scale spatial genetic structure to indicate the presence of non-random evolutionary processes. Broodstock collection of L. argentimaculatus need not be geographically restricted in eastern Australia, but fisheries management should consider variation in life history and recruitment success at the species’ edge.

Phylogenetics, patterns of genetic variation and population dynamics of Trypanosoma terrestris support both coevolution and ecological host-fitting as processes driving trypanosome evolution

BackgroundA considerable amount of evidence has favored ecological host-fitting, rather than coevolution, as the main mechanism responsible for trypanosome divergence. Nevertheless, beyond the study of human pathogenic trypanosomes, the genetic basis of host specificity among trypanosomes isolated from forest-inhabiting hosts remains largely unknown.MethodsTo test possible scenarios on ecological host-fitting and coevolution, we combined a host capture recapture strategy with parasite genetic data and studied the genetic variation, population dynamics and phylogenetic relationships of Trypanosoma terrestris, a recently described trypanosome species isolated from lowland tapirs in the Brazilian Pantanal and Atlantic Forest biomes.ResultsWe made inferences of T. terrestris population structure at three possible sources of genetic variation: geography, tapir hosts and ‘putative’ vectors. We found evidence of a bottleneck affecting the contemporary patterns of parasite genetic structure, resulting in little genetic diversity and no evidence of genetic structure among hosts or biomes. Despite this, a strongly divergent haplotype was recorded at a microgeographical scale in the landscape of Nhecolândia in the Pantanal. However, although tapirs are promoting the dispersion of the parasites through the landscape, neither geographical barriers nor tapir hosts were involved in the isolation of this haplotype. Taken together, these findings suggest that either host-switching promoted by putative vectors or declining tapir population densities are influencing the current parasite population dynamics and genetic structure. Similarly, phylogenetic analyses revealed that T. terrestris is strongly linked to the evolutionary history of its perissodactyl hosts, suggesting a coevolving scenario between Perissodactyla and their trypanosomes. Additionally, T. terrestris and T. grayi are closely related, further indicating that host-switching is a common feature promoting trypanosome evolution.ConclusionsThis study provides two lines of evidence, both micro- and macroevolutionary, suggesting that both host-switching by ecological fitting and coevolution are two important and non-mutually-exclusive processes driving the evolution of trypanosomes. In line with other parasite systems, our results support that even in the face of host specialization and coevolution, host-switching may be common and is an important determinant of parasite diversification.

Inter-boundary comparison between Bass Strait and southeastern Tasmania reveals taxon-specific effects of phylogeographic determinants in marine Mollusca

Comparative analysis may help elucidate how interacting influences have shaped regional phylogeography. The coasts of southeastern Australia potentially offer an opportunity for such analysis by comparison of southeastern Tasmania and Bass Strait. The latter has been extensively studied but there are fewer phylogeographic studies in southeastern Tasmania and these have mostly shown little evidence of genetic structure. The possibility that snails of the Austrocochlea constricta s.l complex have such structure was investigated here using nuclear and mitochondrial DNA sequences. Similarly to the few known examples of geographically-structured taxa in the region, especially the gastropod genus Nerita, most differentiation in A. constricta s.l. occurs between localities east and west of the Tasman Peninsula. In contrast, Nerita and A. constricta s. l. differ in their phylogeographic structure around Bass Strait. Possible explanations of inter-regional phylogeographic differences include the interaction of breeding season and current variability, whether the geographically partitioned genetic lineages represent intra-specific or species-level divergence and the decoupling of landbridge formation and sea surface temperature at the beginning and end of glacial maxima.

Evidence of genetic structure in a wide‐ranging and highly mobile soaring scavenger, the Andean condor

AbstractAimEvaluating the patterns of genetic variation and population connectivity is fundamental to effectively designing and implementing conservation strategies for threatened species. However, connectivity patterns in highly mobile vertebrates, and especially in avian species, are often overlooked as it is generally assumed to be driven by demographic panmixia or isolation by distance. Herein, we investigated the genetic structure and patterns of connectivity across four biomes in a highly vagile bird, the Andean condor (Vultur gryphus).LocationFour major Neotropical biomes of Argentina (&gt;300,000 km2): Puna, Monte, Chaco and Patagonia.MethodsWe genotyped 13 polymorphic microsatellite loci plus one sex‐determining gene in 300 moulted feathers from 13 roosting sites in the core of species distributional range. We quantified levels of genetic differentiation, population structure, effective gene flow, genetic diversity and assessed sex‐biased dispersal events.ResultsWe detected genetic structure with a moderate differentiation between the north (Puna and Chaco) and south (Patagonia) regions with a contact zone in the central area (Monte). We observed a spatial pattern of genetic patches with higher levels of gene flow along the Andes range. Although we found no indication of bottlenecks or inbreeding, we observed larger effective population sizes in the south compared to the northern region.Main conclusionsOur study revealed that, despite the high dispersal potential of condors, demographic panmixia is not consolidated, even in the core of this species range. Our analyses further suggest that gene flow rate is modulated by topographic features, as condors may disperse more following the natural updrafts and lifts along the Andean mountains. Conservation initiatives should prioritize the protection of the Andean corridor to maintain connectivity between the apparent source from Patagonia to the northern biomes.

DNA barcoding of economically important freshwater fish species from north-central Nigeria uncovers cryptic diversity.

This study examines the utility of morphology and DNA barcoding in species identification of freshwater fishes from north‐central Nigeria. We compared molecular data (mitochondrial cytochrome c oxidase subunit I (COI) sequences) of 136 de novo samples from 53 morphologically identified species alongside others in GenBank and BOLD databases. Using DNA sequence similarity‐based (≥97% cutoff) identification technique, 50 (94.30%) and 24 (45.30%) species were identified to species level using GenBank and BOLD databases, respectively. Furthermore, we identified cases of taxonomic problems in 26 (49.00%) morphologically identified species. There were also four (7.10%) cases of mismatch in DNA barcoding in which our query sequence in GenBank and BOLD showed a sequence match with different species names. Using DNA barcode reference data, we also identified four unknown fish samples collected from fishermen to species level. Our Neighbor‐joining (NJ) tree analysis recovers several intraspecific species clusters with strong bootstrap support (≥95%). Analysis uncovers two well‐supported lineages within Schilbe intermedius. The Bayesian phylogenetic analyses of Nigerian S. intermedius with others from GenBank recover four lineages. Evidence of genetic structuring is consistent with geographic regions of sub‐Saharan Africa. Thus, cryptic lineage diversity may illustrate species’ adaptive responses to local environmental conditions. Finally, our study underscores the importance of incorporating morphology and DNA barcoding in species identification. Although developing a complete DNA barcode reference library for Nigerian ichthyofauna will facilitate species identification and diversity studies, taxonomic revisions of DNA sequences submitted in databases alongside voucher specimens are necessary for a reliable taxonomic and diversity inventory.