Parapatric Distribution Research Articles

Secondary contact zone and genetic introgression in closely related haplodiploid social spider mites.

How frequently hybridisation and gene flow occur in the contact zones of diverging taxa is important for understanding the speciation process. Stigmaeopsis sabelisi and Stigmaeopsis miscanthi high-aggression form (hereafter, S. miscanthi HG) are haplodiploid, social spider mites that infest the Chinese silver grass, Miscanthus sinensis. These two species are closely related and parapatrically distributed in Japan. In mountainous areas, S. sabelisi and S. miscanthi HG are often found in the highlands and lowlands, respectively, suggesting that they are in contact at intermediate altitudes. It is estimated that they diverged from their common ancestors distributed in subtropical regions (south of Japan) during the last glacial period, expanded their distribution into the Japanese Archipelago, and came to have such a parapatric distribution (secondary contact). As their reproductive isolation is strong but incomplete, hybridisation and genetic introgression are expected at their distributional boundaries. In this study, we investigated their spatial distribution patterns along the elevation on Mt. Amagi using male morphological differences, and investigated their hybridisation status using single-nucleotide polymorphisms by MIG-seq. We found their contact zone at altitudes of 150-430 m, suggesting that their contact zone is prevalent in the parapatric area, which is in line with a previous study. Interspecific mating was predicted based on the sex ratio in the contact zone. No obvious hybrids were found, but genetic introgression was detected although it was extremely low.

Phylogenetic and phylogeographic insights into Sri Lankan killifishes (Teleostei: Aplocheilidae).

Three nominal species of the killifish genus Aplocheilus are reported from the lowlands of Sri Lanka. Two of these, Aplocheilus dayi and Aplocheilus werneri, are considered endemic to the island, whereas Aplocheilus parvus is reported from both Sri Lanka and Peninsular India. Here, based on a collection from 28 locations in Sri Lanka, also including a dataset of Asian Aplocheilus downloaded from GenBank, we present a phylogeny constructed from the mitochondrial cytochrome b (cytb), mitochondrial cytochrome c oxidase subunit 1 (cox1), and nuclear recombination activating protein 1 (rag1), and investigate the interrelationships of the species of Aplocheilus in Sri Lanka. The endemic Sri Lankan aplocheilid clade comprising A. dayi and A. werneri is recovered as the sister group to the clade comprising A. parvus from Sri Lanka and Aplocheilus blockii from Peninsular India. The reciprocal monophyly of A. dayi and A. werneri is not supported in our molecular phylogeny. A. dayi and A. werneri display strong sexual dimorphism, but species-level differences are subtle, explained mostly by pigmentation patterns. Their phenotypes exhibit a parapatric distribution and may represent locally adapted forms of a single species. Alternatively, the present study does not rule out the possibility that A. dayi and A. werneri may represent an incipient species pair or that they have undergone introgression or hybridization in their contact zones. We provide evidence that the Nilwala-Gin region of southwestern Sri Lanka may have acted as a drought refugium for these fishes.

Deep genetic divergence among bluefish (Pomatomus saltatrix) of the Southwestern Atlantic

AbstractNeglected cryptic diversity can lead to the permanent loss of locally adapted alleles, which can reduce resilience to rapid environmental change. It can also result in overestimation of fisheries stock sizes that can result from treating different species as if they belonged to one. Bluefish (Pomatomus saltatrix) is considered a circumtropical and subtropical species and an important fishery resource all over the world. Differences in ecologically relevant traits are observed among isolated populations. Also, in the Southwestern Atlantic, molecular data suggest multiple populations, but these are treated as a single fish stock by regulatory agencies due to a lack of definitive information. We used whole mitogenome sequences, nuclear (rho) and mitochondrial (coxI and cytb) genes, as well as microsatellites to investigate historical and current genetic population structure and parameters of bluefish in the Western Atlantic. A total of 263 samples were collected along the Brazilian coast and in the USA (New Jersey, Northwest Atlantic). Data revealed the existence of two evolutionarily significant units (ESU) of bluefish along the South American coast, later confirmed by whole mitogenome sequencing of both haplogroups. These two ESUs have a mostly parapatric distribution, with some areas of overlap, which vary along the year. We also conducted seasonal sampling in Brazil to investigate migration patterns. ESUs occur mostly north and south of parallel 23° 40′ S, with an overlap area that varied seasonally. The level of differentiation between those two ESUs in the SW Atlantic, even in sympatry, is as high as that found between them and those from the NW Atlantic and Europe. Parapatric distribution and restricted gene flow suggest the existence of ecological barriers and local adaptation. The splitting of an ancient population from the Southwestern Atlantic into two putative species is important to understand bluefish evolutionary diversification and has implications for fishery regulatory measures in Brazil.

Variations in water economy traits in two Sphagnum species across their distribution boundaries.

We assessed changes in traits associated with water economy across climatic gradients in the ecologically similar peat mosses Sphagnum cuspidatum and Sphagnum lindbergii. These species have parapatric distributions in Europe and have similar niches in bogs. Sphagnum species of bogs are closely related, with a large degree of microhabitat niche overlap between many species that can be functionally very similar. Despite this, ecologically similar species do have different distributional ranges along climatic gradients that partly overlap. These gradients may favor particular Sphagnum traits, especially in relation to water economy, which can be hypothesized to drive species divergence by character displacement. We investigated traits relevant for water economy of two parapatric bryophytes (Sphagnum cuspidatum and S. lindbergii) across the border of their distributional limits. We included both shoot traits and canopy traits, i.e., collective traits of the moss surface, quantified by photogrammetry. The two species are ecologically similar and occur at similar positions along the hydrological gradient in bogs. The biggest differences between the species were expressed in the variations of their canopy surfaces, particularly surface roughness and in the responses of important traits such as capitulum mass to climate. We did not find support for character displacement, because traits were not more dissimilar in sympatric than in allopatric populations. Our results suggest that parapatry within Sphagnum can be understood from just a few climatic variables and that climatic factors are stronger drivers than competition behind trait variation within these species of Sphagnum.

Revisiting a cryptic species complex: interspecific gene flow among woodland salamanders in the Blue Ridge Mountains of northern Georgia, USA

Abstract The complex topography of mountainous landscapes can create biogeographical barriers and promote allopatric speciation—even among morphologically cryptic species. However, these biogeographical barriers may not be permanent, and secondary contact between previously independently evolving populations can result in hybridization and introgression. In this study, we used genome-wide single nucleotide polymorphism data to re-examine a classic example of cryptic species in the Appalachian Mountains: the slimy salamander (Plethodon glutinosus) species complex. This group of morphologically similar terrestrial salamanders includes 14 species with parapatric distributions across the eastern USA. We focused on the Chattahoochee slimy salamander (P. chattahoochee) in northern Georgia and used a series of complementary phylogenomic and population genomic analyses to evaluate spatial genetic structure within this species and admixture with at least four other species of parapatric woodland salamanders. Our results highlight the utility of genomic data in clarifying species boundaries and underline the difficulty of species delimitation in organisms with complex evolutionary histories.

Sympatry of Amblyomma eburneum and Amblyomma variegatum on African buffaloes and prevalence of pathogens in ticks

The Amblyomma genus is represented on the African continent by 24 species, out of which 17 are known to occur in different ecological niches of southern Africa. Amblyomma, known for their aggressive hunting behaviour and aptitude as pathogen vectors, are of main concern to travellers, mainly in rural and conservation areas of Africa. In this study, we highlight the overlapping distribution of Amblyomma eburneum and Amblyomma variegatum found on African buffaloes (Syncerus caffer) at Coutada 11, Central Mozambique. In total, 1,039 Amblyomma ticks were collected and morphologically identified using taxonomic keys, and genomic DNA was extracted. They were subjected to reverse line blotting for pathogen identification followed by molecular analysis (COI sequencing) of both tick species. Pathogens such as Ehrlichia ruminantium, Anaplasma centrale, Theileria sp., Babesia sp. and Rickettsia africae were detected, of which R. africae is zoonotic. Ehrlichia ruminantium, R. africae, Theileria mutans and Theileria velifera are well-established pathogens transmitted by Amblyomma ticks; however, Anaplasma spp. and Babesia spp. are not, suggesting residual parasite DNA in the bloodmeal. Little is mentioned in the literature about A. eburneum, including its role as a vector and reservoir for pathogens. In Mozambique A. eburneum is currently restricted to wildlife but the spread of the tick may be observed given the climate change that is occurring. The infection rates for the pathogens in both Amblyomma tick species were lower than expected, but this may be due to the low host density in the forest niche and the innate immunity of these hosts. With the propensity of ticks of the Amblyomma genus to form parapatric distributions, the mechanisms that allows for the overlapping distribution of these two Amblyomma species while maintaining tick species identity is of great interest.

Drivers of genomic landscapes of differentiation across a Populus divergence gradient.

Speciation, the continuous process by which new species form, is often investigated by looking at the variation of nucleotide diversity and differentiation across the genome (hereafter genomic landscapes). A key challenge lies in how to determine the main evolutionary forces at play shaping these patterns. One promising strategy, albeit little used to date, is to comparatively investigate these genomic landscapes as progression through time by using a series of species pairs along a divergence gradient. Here, we resequenced 201 whole-genomes from eight closely related Populus species, with pairs of species at different stages along the divergence gradient to learn more about speciation processes. Using population structure and ancestry analyses, we document extensive introgression between some species pairs, especially those with parapatric distributions. We further investigate genomic landscapes, focusing on within-species (i.e. nucleotide diversity and recombination rate) and among-species (i.e. relative and absolute divergence) summary statistics of diversity and divergence. We observe relatively conserved patterns of genomic divergence across species pairs. Independent of the stage across the divergence gradient, we find support for signatures of linked selection (i.e. the interaction between natural selection and genetic linkage) in shaping these genomic landscapes, along with gene flow and standing genetic variation. We highlight the importance of investigating genomic patterns on multiple species across a divergence gradient and discuss prospects to better understand the evolutionary forces shaping the genomic landscapes of diversity and differentiation.

Cryptic diversity of Crocidura shrews in the savannahs of Eastern and Southern Africa

Crocidura (Eulipotyphla, Soricidae) is the most species-rich genus among mammals, with high cryptic diversity and complicated taxonomy. The hirta-flavescens group of Crocidura represents the most abundant and widespread shrews in savannahs of eastern and southern Africa, making them a suitable phylogeographical model for assessing the role of paleoclimatic changes on current biodiversity in open African habitats. We present the first comprehensive study on the phylogeography, evolutionary history, geographical distribution, systematics, and taxonomy of the group, using the integration of mitochondrial, genome-wide (ddRAD sequencing), morphological and morphometrical data collected from specimens over most of the known geographic distribution. Our genomic data confirmed the monophyly of this group and its sister relationship with the olivieri group of Crocidura. There is a substantial genetic variation within the hirta-flavescens group, with three highly supported clades showing parapatric distribution and which can be distinguished morphologically: C. hirta, distributed in both the Zambezian and Somali-Masai bioregions, C. flavescens, known from South Africa and south-western Zambia, and C. cf. flavescens, which is known to occur only in central and western Tanzania. Morphometric data revealed relatively minor differences between C. hirta and C. cf. flavescens, but they differ in the colouration of the pelage. Diversification of the hirta-flavescens group has most likely happened during phases of grassland expansion and contraction during Plio-Pleistocene climatic cycles. Eastern African Rift system, rivers, and the distinctiveness of Zambezian and Somali-Masai bioregions seem to have also shaped the pattern of their diversity, which is very similar to sympatric rodent species living in open habitats. Finally, we review the group's taxonomy and propose to revalidate C. bloyeti, currently a synonym of C. hirta, including the specimens treated as C. cf. flavescens.

Integrative analysis reveals the divergence and speciation between sister Sooty Copper butterflies Lycaena bleusei and L. tityrus

The comparison of closely related taxa is cornerstone in biology, as understanding mechanisms leading up to differentiation in relation to extant shared characters are powerful tools in interpreting the evolutionary process. Hotspots of biodiversity such as the west-Mediterranean, where many lineages meet are ideal grounds to study these processes. We set to explore the interesting example of Sooty Copper butterflies: widespread Eurasian Lycaena tityrus (Poda, 1761) comes into contact in Iberia with closely related and local endemic, L. bleusei (Oberthür, 1884), which hasn’t always been considered a distinct species. An integrative analysis was designed, combining the use of extensive molecular data (five genes), geometric morphometrics analyses, verified and up-to-date distribution data, and environmental niche modelling, aimed at deciphering their true relationship, their placement within European Lycaena and trace their evolutionary history. We revealed several levels of differentiation: L. bleusei and L. tityrus appear to be reciprocally monophyletic independent gene-pools, distinct in all genes analysed, having mutually diverged 4.8 Ma ago. L. tityrus but not L. bleusei, further displays a genetic structure compatible with several glacial refugia, where populations assignable to infraspecific taxa surface. Conversely, L. bleusei shows a loss in mtDNA diversity in relation to nuDNA. Morphological analyses differentiate both species according to size and shape but also discriminate strong seasonal and sexual traits and a geographical phenotype segregation in L. tityrus. Finally, updated distribution and its modelling for current and glacial timeframes reveal both species respond differently to environmental variables, defining a mostly parapatric distribution and an overlapping belt where sympatry was recovered. During the last glacial maximum, a wider expansion in L. bleusei distribution explains current isolated populations. Our study highlights the importance of gathering several lines of evidence when deciphering the relationships between closely related populations in the fringe of cryptic species realm.

Parapatry of Phanaeus splendidulus and P. dejeani (Coleoptera: Scarabaeidae: Scarabaeinae) in two mountain ranges in the Atlantic Forest

AbstractParapatry occurs when species exhibit adjacent distributions in space, with contact in their boundaries, with or without overlapping. Many factors can generate this pattern, such as environmental conditions and interspecific competition. Mountains are excellent systems to study parapatry because they exhibit large environmental heterogeneity within a small geographical area. Phanaeus splendidulus and P. dejeani are two similar dung beetle species with apparent sympatric distributions at geographical scale, but with a hypothesized parapatric distribution in mountains. We assessed whether P. splendidulus and P. dejeani indeed exhibit a parapatric distribution in two mountain ranges in the Atlantic Forest. We also tested the effects of environmental conditions and interspecific competition on the observed pattern of abundance for both species for one mountain. We placed pitfall traps at every 50 m of elevation from 600 to 2400 m a.s.l. at Itatiaia National Park and from 100 to 2050 m a.s.l. at Serra dos Órgãos National Park in Brazil. We used temperature, vegetation cover, litter volume and soil granulometry as environmental predictors of each species abundance and the abundance of its congeneric species as a measure of interspecific competition. Phanaeus splendidulus and P. dejeani indeed exhibited a parapatric distribution and a small overlapping area, with P. splendidulus reaching up to 1450 m a.s.l. in Itatiaia National Park and 1250 m a.s.l. in Serra dos Órgãos National Park, and P. dejeani occurring above to 1000 m a.s.l. Only maximum temperature was significantly related to species abundance. Maximum temperature affected positively P. splendidulus abundance and negatively P. dejeani, suggesting that these species have opposite climate preferences. The abundance of the congeneric species was not significant for either species. Understand species distributions and what drives them is critical to understand the evolution of species interaction, their responses to the environment and for conservation, in a world of climate change.

Why are there so many species of mining bees (Hymenoptera, Andrenidae)? The possible roles of phenology and Wolbachia incompatibility in maintaining species boundaries in the Andrena proxima‐complex

AbstractThe factors leading to the extraordinary diversity of the bees of the genus Andrena Fabricius, the second most speciose genus among bees, remain largely unknown. To examine the pattern of diversification in this genus, we investigate species boundaries within the controversial Andrena proxima‐complex using a dataset of ultra‐conserved elements and various species delimitation analyses (admixture analyses, BPP, DAPC). Our results confirm the presence of three separate species in this species group (Andrena proxima (Kirby), A. ampla Warncke and A. alutacea Stöckhert) and suggest very low levels of interspecific gene flow. Andrena proxima and A. alutacea are regularly found in sympatry, suggesting an advanced stage of speciation. By contrast, A. ampla shows a parapatric distribution with both other species. Andrena alutacea harbours a unique strain of Wolbachia Hertig, absent in the other two species, which are infected by the two same strains of Wolbachia. In addition, the three species have distinct phenologies, with A. proxima flying earlier in the season and A. alutacea significantly later; the phenology of A. ampla is intermediate. Our results suggest that Wolbachia‐induced incompatibilities and phenological differences maintain species boundaries in this group. The most advanced stage of speciation is observed in the two species showing putatively incompatible strains of Wolbachia and strongly distinct phenologies, A. alutacea and A. proxima. We propose that the smaller differences in phenological differentiation between A. ampla and both other species may explain the observed pattern of parapatric distribution. We discuss how these factors may underlie the high diversification rate observed in other groups of Andrena, a genus characterized by particularly variable and short flying periods.

Population genomic analyses reveal hybridization and marked differences in genetic structure of Scurria limpet sister species with parapatric distributions across the South Eastern Pacific.

The study of sister species that occur in parapatry around biogeographic transition zones can help understand the evolutionary processes that underlie the changes in species composition across biogeographic transition zones. The South Eastern Pacific (SEP) coast is a highly productive coastal system that exhibits a broad biogeographic transition zone around 30–35°S. Here, we present a comparative genome‐wide analysis of the sister species Scurria viridula and Scurria zebrina, that occur in parapatry and whose poleward and equatorward range edges intersect in the 30–35°S SEP biogeographic transition zone. We sampled 118 specimens sourced from nine sites from Tocopilla (22°S) to Chiloé (41°S) including one site where both species overlap and analyzed over 8000 biallelic single nucleotide polymorphisms. We found evidence of hybridization between these species in the contact zone and found significant but contrasting population structures for both species. Our results indicate that the genetic structure in S. viridula, which is currently expanding its range poleward, follows a simple isolation by distance model with no traces of natural selection (no evidence of outlier loci). In contrast, S. zebrina, which has its equatorward range edge at the transition zone, displayed a pronounced genetic break approximately at 32–34°S, along a region of marked environmental heterogeneity in association with a semi‐permanent coastal upwelling regime. For S. zebrina we also found 43 outlier loci associated with this genetic break, with a significant proportion of them clustering in a single linkage group. This marked difference in the presence of outlier loci between species suggests that they could be responding differently to local environmental challenges found at their overlapping geographic range edges, thus providing important new insights about genomic changes around biogeographic transition zones in sister species and the forces that shape genetic diversity in intertidal marine species.

Diversity and Distribution of the Inland Water Decapods of Sicily (Crustacea, Malacostraca)

The current knowledge of Sicilian inland water decapod malacostracans is scarce and an updated synopsis on species distribution is lacking. Therefore, we reviewed the checklist and recent distribution of Sicilian inland water decapods based on published and unpublished records and novel observations with the aim of providing an exhaustive repository, also to be used as a sound baseline for future surveys. Overall, five native decapod species occur in the study area, i.e., the atyid shrimp Atyaephyra desmarestii, the palaemonid shrimps Palaemon adspersus, P. antennarius, and P. elegans, and the freshwater crab Potamon fluviatile, and their current local distributions are described. In addition, three alien species were recorded: the common yabby Cherax destructor and the red swamp crayfish Procambarus clarkii, strictly linked to inland waters, and the Atlantic blue crab Callinectes sapidus, a mainly marine species that can also colonise the lower stretches of rivers and coastal brackish waters. The collected data suggest the existence of a partial segregation of native versus non-native species, with the latter currently confined to coastal water bodies and the lower stretches of rivers. Moreover, the exclusively freshwater caridean A. desmarestii and P. antennarius show a parapatric distribution in the study area, which may suggest the existence of mutual exclusion phenomena. The results obtained raise some concerns about the effects of alien species on the native biota, and dedicated monitoring and management strategies should be implemented in order to better understand and mitigate their impact.

Different Roles of Introgression on the Demographic Change in Two Snakebark Maples, Acer caudatifolium and A. morrisonense, with Contrasted Postglacial Expansion Routes.

Hybridization frequently occurs in plant species. With repeated backcross, the introgression may influence evolutionary trajectories through the entry of foreign genes. However, the genetic admixture via hybridization events is often confused with the ancestral polymorphism, especially in closely related species that have experienced similar evolutionary events. In Taiwan, two independent-originated endemic snakebark maples have contrasted postglacial range expansion routes: northward and upward expansion in Acer caudatifolium and downward expansion in A. morrisonense. The range expansion causes the current parapatric distribution, increasing the possibility of introgression. This study elucidates how their genetic variation reflects introgression and historical demography. With 17 EST-SSR markers among the intensely sampled 657 individuals, we confirmed that the genetic admixture between species mainly was attributed to recent introgression instead of common ancestral polymorphism. The secondary contact scenario inferred by approximate Bayesian computation suggested that A. morrisonense received more genetic variations from A. caudatifolium. Introgression occurred in colonized Taiwan around the early Last Glacial Period. Furthermore, the demography of A. caudatifolium was more severely affected by introgression than A. morrisonense, especially in the wavefront populations with high altitude range expansion, implying an altitude-related adaptive introgression. In contrast, A. morrisonense exhibited ubiquitous introgression independent of postglacial expansion, suggesting that introgression in A. morrisonense was neutral. In terms of different genetic consequences, introgression had different demographic impacts on species with different altitude expansion directions even under the same climate-change conditions within an island.

An evaluation of parapatric distributions among ecologically similar rattlesnakes (Viperidae:Crotalus) in North American warm deserts

AbstractParapatric distributions between ecologically similar species have the potential to reveal the effects of limiting similarity in large-scale patterns of species coexistence. We present a qualitative model that predicts three different types of parapatric boundaries between competing species pairs: gap parapatry, abrupt parapatry and narrow sympatry. Our model integrates both niche-based and neutral theory perspectives of coexistence in the context of climatic tolerances, species equivalence, contingencies of dispersal history, priority effects and a heterogeneous patchwork of optimal and suboptimal habitat. Using species distribution models, tests of niche overlap and phylogeographical data, we evaluated assumptions and conditions of this model for four species of mostly allopatric, rock-dwelling rattlesnakes (Viperidae: Crotalus) inhabiting arid mountain ranges of the Mohave–Sonoran desert system of western North America. Our model was adequate for predicting the different types of range boundaries observed across this guild of ecologically similar species. Where species distributions were separated by a steep climatic gradient without evidence of recent dispersal, we observed gap parapatry; where historical dispersal was asymmetric, we observed abrupt parapatry; and finally, where historical dispersal was symmetric, we observed narrow sympatry.

Molecular evidence of introgressive hybridization between related species Jankowski's Bunting (Emberiza jankowskii) and Meadow Bunting (Emberiza cioides) (Aves: Passeriformes)

Natural hybridization, which often occurs between closely related species exhibiting sympatric or parapatric distributions, is an important source of genetic variation within populations. The closely related Jankowski's Bunting (Emberiza jankowskii) and Meadow Bunting (E. cioides) are similar in morphology and genetics, occupy overlapping niches, and are sympatric in eastern Inner Mongolia. Previous studies have reported trans-species polymorphisms of alleles between the two species, as well as an unexpectedly high genetic diversity of the endangered E. jankowskii. We speculate that introgressive hybridization has occurred between the two species and contributed to the additional unexpected variation to E. jankowskii. We used mitochondrial NADH dehydrogenase subunit 2 (ND2) gene and 15 nuclear microsatellite markers to compare the genetic diversity of E. jankowskii and E. cioides, and inferred the origin of trans-species polymorphisms between the two species by phylogenetic reconstruction and Bayesian cluster analysis. The two species could be clearly distinguished by population cluster analysis. Despite the large number of mutational differences, we still detected sharing of major haplotypes and the presence of hybrids between the two species. Our study confirmed that weak introgressive hybridization has occurred between sympatric E. jankowskii and E. cioides, which may be mediated by female E. cioides individuals, and that interspecific introgression has contributed to the maintenance of high genetic diversity in E. jankowskii. While being wary of the potential negative effects of introgressive hybridization, we suggest that expanding the habitat of E. jankowskii remains the most effective conservation strategy at present.

Evidence for ecological processes driving speciation among endemic lizards of Madagascar.

Although genetic patterns produced by population isolation during speciation are well documented, the biogeographic and ecological processes that trigger speciation remain poorly understood. Alternative hypotheses for the biogeography and ecology of speciation include geographic isolation combined with niche conservation (soft allopatry) or parapatric distribution on an environmental gradient with niche divergence (ecological speciation). Here, we use species' distributions, environmental data, and two null models (the Random Translation and Rotation and the Background Similarity Test) to test these alternative hypotheses among 28 sister pairs of microendemic lizards in Madagascar. Our results demonstrate strong bimodal peaks along a niche divergence-conservation spectrum, with at least 25 out of 28 sister pairs exhibiting either niche conservation or divergence, and the remaining pairs showing weak ecological signals. Yet despite these significant results, we do not find strong associations of niche conservation with allopatric distributions or niche divergence with parapatric distributions. Our findings thus provide strong evidence of a role for ecological processes driving speciation, rather than the classic expectation of speciation through geographic isolation, but demonstrate that the link between ecological speciation and parapatry is complex and requires further analysis of a broader taxonomic sample to fully resolve.

Identifying regional environmental factors driving differences in climatic niche overlap inPeromyscusmice

AbstractDifferent groups of taxa exhibit varying degree of climatic niche conservatism or divergence due to evolutionary constraints imposed on taxa and distributional relationships among them. Herein, we explore to what extent regional environmental conditions that taxa occupy affect climatic niche overlap between pairs of congeneric species of Peromyscus mice exhibiting allopatric, parapatric, or sympatric distributions. We used Bayesian generalized linear mixed models to identify environmental variables that best explain differences in climatic niche overlap between species. Our results suggest that regional environmental conditions explain 13–44% of variation in climatic niche overlap. Specifically, allopatric and parapatric species pairs are more likely to occupy similar climatic niches in areas that are topographically less complex but with more complex habitats. Sympatric species are more likely to occupy similar climatic niches in areas that promote local niche partitioning (topographically less complex, warmer winter temperatures, higher precipitation, and higher habitat complexity on a local scale). By understanding the relationship between regional environmental conditions and niche overlap, we highlight how differences in geography can contribute to shaping niches of congeneric species.

Evidence of cryptic diversity inPodarcis peloponnesiacusand re‐evaluation of its current taxonomy; insights from genetic, morphological, and ecological data

The Peloponnese wall lizard, Podarcis peloponnesiacus, is endemic to the Peloponnese. Although the phylogeny and species diversity of the Balkan species of Podarcis have been extensively studied, the intraspecific relationships of P. peloponnesiacus are not yet well defined. The aim of this study was to investigate the intraspecific diversity in this species and clarify its taxonomic status by analyzing eight gene fragments (two mitochondrial and six nuclear) and several morphological traits, typically used for systematic inferences within the genus Podarcis. Together with ecological niche modeling, we provided an integrative evaluation of the differentiation between lineages. The combination of several phylogenetic, species delimitation, and chronophylogenetic analyses revealed the existence of two highly supported and divergent clades with a distinct geographical and parapatric distribution and high niche overlap. The differentiation of the two clades dates back to the Pleistocene and is probably correlated with the paleogeography of the Peloponnese. These clades also differed in several phenotypic traits, which, however, exhibit extensive overlap and are not fully diagnostic. The combination of the above results allowed us to identify the two revealed clades as distinct species.

Development and evaluation of a loop-mediated isothermal amplification (LAMP) assay for quick identification of the Japanese salamander Hynobius tokyoensis.

Species identification using molecular techniques has recently become common for various taxa. Loop-mediated isothermal amplification (LAMP) is one of the easiest and least expensive molecular identification methods. Although few studies have developed LAMP assays for amphibians, we believe that LAMP is also useful for identifying endangered amphibians. Hynobius tokyoensis and H. lichenatus occur in Honshu, Japan, and have parapatric distributions. They are similar morphologically, especially at early developmental stages, including eggs and larvae. Hynobius tokyoensis has been listed as a national endangered species in Japan since 2020, and unambiguous identification of these species is therefore important for their conservation and management. In this study, we developed a LAMP primer set for the mitochondrial cytochrome b region to detect H. tokyoensis, and we evaluated the LAMP assay using total genomic DNA from four H. tokyoensis and three H. lichenatus individuals from across most of their ranges. Our LAMP primer set could distinguish these two species. This study should help to establish LAMP assays for other endangered species and morphologically similar species.