Explore the vast range of titles available.

New technological methods, such as rapidly developing molecular approaches, often provide new tools for scientific advances. However, these new tools are often not utilized equally across different research areas, possibly leading to disparities in progress between these areas. Here, we use empirical evidence from the scientific literature to test for potential discrepancies in the use of genetic tools to study parasitic vs non-parasitic organisms across three distinguishable molecular periods, the allozyme, nucleotide and genomics periods. Publications on parasites constitute only a fraction (<5%) of the total research output across all molecular periods and are dominated by medically relevant parasites (especially protists), particularly during the early phase of each period. Our analysis suggests an increasing complexity of topics and research questions being addressed with the development of more sophisticated molecular tools, with the research focus between the periods shifting from predominantly species discovery to broader theory-focused questions. We conclude that both new and older molecular methods offer powerful tools for research on parasites, including their diverse roles in ecosystems and their relevance as human pathogens. While older methods, such as barcoding approaches, will continue to feature in the molecular toolbox of parasitologists for years to come, we encourage parasitologists to be more responsive to new approaches that provide the tools to address broader questions.

North American tree species, subspecies and genetic varieties have primarily evolved in a landscape of extensive continental ice and restricted temperate climate environments. Here, we reconstruct the refugial history of western North American trees since the last glacial maximum using species distribution models, validated against 3571 palaeoecological records. We investigate how modern subspecies structure and genetic diversity corresponds to modelled glacial refugia, based on a meta-analysis of allelic richness and expected heterozygosity for 473 populations of 22 tree species. We find that species with strong genetic differentiation into subspecies had widespread and large glacial refugia, whereas species with restricted refugia show no differentiation among populations and little genetic diversity, despite being common over a wide range of environments today. In addition, a strong relationship between allelic richness and the size of modelled glacial refugia (r2 = 0.55) suggest that population bottlenecks during glacial periods had a pronounced effect on the presence of rare alleles.

(1) Background: Originally described as a single taxon, Peripatoides novaezealandiae (Hutton, 1876) are distributed across both main islands of New Zealand; the existence of multiple distinct lineages of live-bearing Onychophora across this spatial range has gradually emerged. Morphological conservatism obscured the true endemic diversity, and the inclusion of molecular tools has been instrumental in revealing these cryptic taxa. (2) Methods: Here, we review the diversity of the ovoviviparous Onychophora of New Zealand through a re-analysis of allozyme genotype data, mitochondrial DNA cytochrome oxidase subunit I sequences, geographic information and morphology. (3) Results: New analysis of the multilocus biallelic nuclear data using methods that do not require a priori assumptions of population assignment support at least six lineages of ovoviviparous Peripatoides in northern New Zealand, and mtDNA sequence variation is consistent with these divisions. Expansion of mitochondrial DNA sequence data, including representation of all existing taxa and additional populations extends our knowledge of the scale of sympatry among taxa and shows that three other lineages from southern South Island can be added to the Peripatoides list, and names are proposed here. In total, 10 species of Peripatoides can be recognised with current data.

Mammals have played a foundational role in the explosive growth of phylogeography over the past 30 years that it has been a recognized discipline. Novel discoveries of geographic patterns and processes using phylogeographic approaches have integrated disciplines including biogeography, evolutionary biology, ecology, and conservation biology. Here, we use several approaches to survey the scope and influence of phylogeography, beginning with use of a well-studied family of North American rodents to contrast information content derived from DNA-based phylogeography versus a popular older method, allozyme electrophoresis, of assaying genetic variation within and among species across geography. We conclude that phylogeography has elevated the quality of insights attainable regarding, for example, the causal role of Earth history events in processes including lineage divergence, speciation, and adaptive evolution. Next, we use searches of the Web of Science with an array of terms that return information on molecular markers employed, numbers of individuals and localities examined, time frames investigated, historical processes and ways that species and biotas have responded to Earth history, design of phylogeographic studies (e.g., single-taxon versus comparative), and current gaps in taxonomic and geographic sampling. Highlighted results from phylogeographic assays include: an average of 3.3 cryptic lineages per taxonomic species in rodents; a bias in number of studies toward less-diverse biogeographic regions; and a relatively low number of mammalian genera studied. We conclude with predicted and recommended directions for future growth in mammalian phylogeography, including prospects for an increasing role of next generation-based genomics.

.— The ability of populations to undergo adaptive evolution depends on the presence of quantitative genetic variation for ecologically important traits. Although molecular measures are widely used as surrogates for quantitative genetic variation, there is controversy about the strength of the relationship between the two. To resolve this issue, we carried out a meta‐analysis based on 71 datasets. The mean correlation between molecular and quantitative measures of genetic variation was weak (r = 0.217). Furthermore, there was no significant relationship between the two measures for life‐history traits (r =−0.11) or for the quantitative measure generally considered as the best indicator of adaptive potential, heritability (r =−0.08). Consequently, molecular measures of genetic diversity have only a very limited ability to predict quantitative genetic variability. When information about a population's short‐term evolutionary potential or estimates of local adaptation and population divergence are required, quantitative genetic variation should be measured directly.

Drosophila melanogaster invaded Australia around 100 years ago, most likely through a northern invasion. The wide range of climatic conditions in eastern Australia across which D. melanogaster is now found provides an opportunity for researchers to identify traits and genes that are associated with climatic adaptation. Allozyme studies indicate clinal patterns for at least four loci including a strong linear cline in Adh and a non-linear cline in α-Gpdh. Inversion clines were initially established from cytological studies but have now been validated with larger sample sizes using molecular markers for breakpoints. Recent collections indicate that some genetic markers (Adh and In(3R)Payne) have changed over the last 20 years reflecting continuing evolution. Heritable clines have been established for quantitative traits including wing length/area, thorax length and cold and heat resistance. A cline in egg size independent of body size and a weak cline in competitive ability have also been established. Postulated clinal patterns for resistance to desiccation and starvation have not been supported by extensive sampling. Experiments under laboratory and semi-natural conditions have suggested selective factors generating clinal patterns, particularly for reproductive patterns over winter. Attempts are being made to link clinal variation in traits to specific genes using QTL analysis and the candidate locus approach, and to identify the genetic architecture of trait variation along the cline. This is proving difficult because of inversion polymorphisms that generate disequilibrium among genes. Substantial gaps still remain in linking clines to field selection and understanding the genetic and physiological basis of the adaptive shifts. However D. melanogaster populations in eastern Australia remain an excellent resource for understanding past and future evolutionary responses to climate change.

Intraspecific genetic variation can have similar effects as species diversity on ecosystem function; understanding such variation is important, particularly for ecological key species. The brown trout plays central roles in many northern freshwater ecosystems, and several cases of sympatric brown trout populations have been detected in freshwater lakes based on apparent morphological differences. In some rare cases, sympatric, genetically distinct populations lacking visible phenotypic differences have been detected based on genetic data alone. Detecting such “cryptic” sympatric populations without prior grouping of individuals based on phenotypic characteristics is more difficult statistically, though. The aim of the present study is to delineate the spatial connectivity of two cryptic, sympatric genetic clusters of brown trout discovered in two interconnected, tiny subarctic Swedish lakes. The structures were detected using allozyme markers, and have been monitored over time. Here, we confirm their existence for almost three decades and report that these cryptic, sympatric populations exhibit very different connectivity patterns to brown trout of nearby lakes. One of the clusters is relatively isolated while the other one shows high genetic similarity to downstream populations. There are indications of different spawning sites as reflected in genetic structuring among parr from different creeks. We used >3000 SNPs on a subsample and find that the SNPs largely confirm the allozyme pattern but give considerably lower F ST values, and potentially indicate further structuring within populations. This type of complex genetic substructuring over microgeographical scales might be more common than anticipated and needs to be considered in conservation management.

The core–periphery hypothesis (CPH) predicts that genetic diversity is greatest at the centre and lowest at the edges of a species' distribution because genetic diversity is a function of a species' abundance, which is also expected to be greatest at the centre and lowest at the edges of the distribution. Variants of the CPH include the ‘Ramped North' (greatest variation in the north), the ‘Ramped South' (greatest in the south), and the ‘Abundant Edge' (greatest at the distributional edges). Here, we present the first standardised multi‐phylum analysis of the CPH using nine indices of genetic diversity for New Zealand's marine biota, covering 52 species. Based on 80 studies across eight phyla, spatial variation in the genetic indices was tested against four models (Normal (N), Ramped North (RN), Ramped South (RS), Abundant Edge (AE)). Only 22.7% of all individual taxon‐specific tests were statistically significant: Ramped North (10.5%), Ramped South (7.4%), Abundant Edge (2.6%) and Normal (2.2%). Nonetheless, amongst the Chordata (Ramped North and Ramped South), Arthropoda (Ramped South) and Mollusca (Ramped North), a reasonably consistent pattern of genetic variation was observed within each phylum. Spatially‐explicit genetic diversity of the remaining taxa fitted different models but without any obvious pattern across the phyla. Generalised binomial testing of observed p‐values for each genetic index across all studies revealed that 10 of 29 tests were significant (5 RN, 2 N, 2 RS, 1 AE). Overall, our meta‐analysis revealed no real support for the CPH and only limited support for a Ramped model (either Ramped North or Ramped South) of spatially‐explicit genetic diversity. For New Zealand coastal marine taxa, we conclude that consistently strong patterns of genetic variation across multiple taxa do not exist and the CPH requires extensive testing from multiple other regions before we can say that such patterns exist, let alone explain them.

Hybridization between the European smooth and palmate newts has recurrently been mentioned in the literature. The only two studies that attempted to quantify the frequency of hybridization and gene admixture between these two species came to strikingly opposite conclusions. According to Arntzen et al. (1998, 42 allozymes), hybrids are rare in nature and introgression negligible, while according to Johanet et al. (2011, 6 microsatellites), introgressive hybridization is significant and widespread across the shared distribution range. To clarify this question, we implemented high-throughput SNP genotyping with diagnostic biallelic SNPs on 965 specimens sampled across Europe. Our results are in line with Arntzen et al., since only two F1 hybrids were identified in two distinct French localities, and no further hybrid generations or backcrosses. Moreover, reanalysis of 78 of the samples previously studied by Johanet et al. (2011) using our SNPs panel could not reproduce their results, suggesting that microsatellite-based inference overestimated the hybridization frequency between these two species. Since we did not detect methodological issues with the analyses of Johanet et al., our results suggest that SNP approaches outperform microsatellite-based assessments of hybridization frequency, and that conclusions previously published on this topic with a small number of microsatellite loci should be taken with caution, and ideally be repeated with an increased genomic coverage.