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Inferring the geographic mode of speciation is essential for explaining the generation and assembly of biodiversity, but has been rarely applied to the temperate flora of China. Fagus longipetiolata and F. lucida are a sister pair of beech species with largely overlapping ranges in subtropical China, however, little is known about the geographic mode of speciation and the formation of their sympatric distributions. In this study, we used IMa2 and fastsimcoal2 to simulate the speciation history of the two sisters. On the basis of 11 nuclear loci screened for 27 populations/species, their divergence time was estimated to 8.37 Mya by IMa2, and weak interspecific gene flow was detected. The simulation by fastsimcoal2 found that F. longipetiolata and F. lucida diverged ~8.53 Mya, then came into contact and hybridized at 0.8 Mya. The extended Bayesian skyline plots indicated that F. lucida began demographic expansion prior to the Pleistocene at 3 Mya, whereas F. longipetiolata increased its effective population size during the Quaternary, between 0.8 and 0.5 Mya. Ecological niche analysis and niche modelling showed that the two beeches had subtle niche differentiation and their projected distributions were largely overlapped across the late Quaternary. These results, coupled with well-studied fossil records in Fagus , demonstrate that these two beech species diverged allopatrically at the high latitudes of the Northern Hemisphere, and came into contact and hybridized with each other after successive migrations into subtropical (i.e. warm temperate) China recently. However, the two beeches may have developed strong intrinsic reproductive barriers due to long-term allopatry, allowing them to coexist in subtropical China. Our results illuminate the assembly history of the temperate woody flora in subtropical China, supporting that many relict temperate lineages in subtropical China may have established their populations recently. [ABSTRACT FROM AUTHOR]

Hydrangea sect. Macrophyllae comprises deciduous shrubs including two species with seven infraspecific taxa distributed throughout the Japanese Archipelago and adjacent areas. In this study, we revealed a phylogeny of Hydrangea sect. Macrophyllae by using a larger dataset of genome-wide SNPs than those employed in a previous study and by adding more comprehensive taxa/populations, which cover the entire distribution of the section. We then revised the taxonomic treatment of sect. Macrophyllae based on the higher-resolution phylogenetic trees obtained in this study. The phylogenetic trees estimated in this study showed five major clades, suggesting that H. serrata var. minamitanii and var. yesoensis should be treated as independent species from other H. serrata, that H. serrata var. australis and var. yakushimensis could be subclassified under the major clades and that var. angustata could be a synonym of var. serrata. The divergence time of these major clades was estimated to be in the Pleistocene. [ABSTRACT FROM AUTHOR]

Aim Location Taxon Methods Results Main Conclusions We studied the niche evolution and diversification modes in transisthmian Alpheus shrimps by examining the interplay between environmental niche divergence and conservatism in allopatric sister species. In a broader perspective, the current study analysed the evolution of climatic niche and the role of the environment in species diversification of Alpheus transisthmian shrimp.Atlantic and Eastern‐Pacific oceans.Alpheus shrimps (Caridea: Alpheidae).We assembled georeferenced occurrences for 33 species of Alpheus (with 24 sister species) from a time‐calibrated molecular phylogeny. We modelled their ecological niches and assessed niche overlap through pairwise comparisons. Additionally, we performed phylogenetic reconstructions of the ancestral environmental niche, for each niche axis.Our results demonstrate that thermal tolerances, food availability and hydrodynamic forces were relevant environmental axes in evolutionary processes in transisthmian species of Alpheus. Among the 528 paired comparisons, we found that most niches were divergent, including in 12 clades formed by pairs of sister species (in only two of these clades were the niches fully equivalent). Phylogenetic reconstructions of ancestral niches showed an initial niche conservatism in all axes, with divergences intensifying in the last 12 million years.We found evidence that confirms the relevance of the environmental changes that occurred in the West Atlantic and East Pacific for niche evolution in transisthmian Alpheus species, as well as for the emergence of some lineages. Our findings provide evidence for different modes of Alpheus species speciation in a period consistent with the closure of the Isthmus of Panama. [ABSTRACT FROM AUTHOR]

Mesalina watsonana is a well‐known species of small lacertid lizards with an extensive species distribution that exhibits high genetic diversity. The species has a wide distribution range in Iran, some parts of Turkmenistan, Afghanistan, Pakistan, and northwest India. This study aims to generate phylogenetic and phylogeographic evidence to derive taxonomic recommendations supporting. Furthermore, this species can be used as a model for examining Iranian Platuea's historical biogeography. We conducted a very detailed sampling of its distribution and used genetic approaches. Phylogenetic analyses were done implementing two mitochondrial (Cytb and 16S) and one nuclear (C‐mos) gene fragments. Combination of these results indicated that seven well‐supported distinct clades exist within this species complex, i.e. Kerman clade, Esfarayen clade, Halil clade, Ardestan clade, M. watsonana clade, Bardaskan Clade, and Khuzestan Clade in Iran. Also, our results revealed that several distinct clades diverged due to geologic events when the Dasht‐e‐Kavir and the Zagros Mountains were formed. It seems that the ancestor of M. watsonana spread to Iranian Plateau before the formation of the Zagros Mountains. Orogenic activities of the Zagros Mountains and the formation of deserts have influenced the separation of these lineages from the Late Miocene by allopatric speciation. Generally, our findings suggest that each of the seven clades corresponding to distinct geographic regions deserves to be elevated to the species level. [ABSTRACT FROM AUTHOR]

A new species of lycaenid butterfly, Paralucia crosbyisp. nov. (Theclinae: Luciini), is described, diagnosed and illustrated from Namadgi National Park, ACT, and adjacent areas in New South Wales in the highlands of south‐eastern Australia. It is most similar to Paralucia spinifera E.D. Edwards & Common, 1978, but comparative morphology of the adult and immature stages indicates fundamental differences between the two species. Maximum Likelihood phylogenetic analysis of mitochondrial cytochrome oxidase subunit I (COI) of all Paralucia species recovered P. crosbyisp. nov. and P. spinifera as reciprocally monophyletic, with a mean uncorrected 'p' pairwise divergence of 0.93%. Paralucia crosbyisp. nov. appears to be a narrow‐range endemic, restricted to dry montane eucalypt open woodland or woodland between 920 and 1130 m asl, in which the mean annual rainfall varies from 700 to 800 mm and where an abundance of the larval food plant Bursaria spinosa Cav. subsp. lasiophylla (E.M.Benn.) L. Cayzer, Crisp & I. Telford (Pittosporaceae) and colonies of the attendant ant Anonychomyrma sp. (itinerans species group) (Dolichoderinae) are established. The immature stages are described, illustrated and compared with those of P. spinifera and P. aurifera (Blanchard, [1848]). Despite being limited to high altitudes, adults fly in late winter–early spring (late July to early October). The species is univoltine, with much of the year (~9 months) passed in the pupal stage. The ecology, biology and life cycle are discussed, and a likely mode of speciation is hypothesised. [ABSTRACT FROM AUTHOR]

Piper globirhachis, a new species from northwestern Amazon, is described and illustrated. It occurs across the Marañon River Valley from its close relative P. nudilimbum with which it has been confounded for ca. 100 yr. Piper globirhachis differs morphologically from P. nudilimbum in having ovate to long-ovate leaf blades and globose inflorescences, vs. elliptic leaves and elongate inflorescences in P. nudilimbum. These species also differ in geographic distribution and ecological niche. A molecular phylogeny based on 135 ITS sequences (125 from Neotropical Piper species and 5 Asian Piper species) enabled the species boundary test (Poisson-tree-processes, PTP) corroborating that these are distinct species. Furthermore, these two species formed a well-supported clade sister to P. subgenus Oxodium (=Schilleria). This phylogeny highlights the importance of allopatric speciation in Piper and provides evidence for the resurrection of Pleiostachyopiper as a subgenus of Neotropical Piper. An identification key for the subgenera of Neotropical Piper is provided. [ABSTRACT FROM AUTHOR]

During 25 surveys of global Phytophthora diversity, conducted between 1998 and 2020, 43 new species were detected in natural ecosystems and, occasionally, in nurseries and outplantings in Europe, Southeast and East Asia and the Americas. Based on a multigene phylogeny of nine nuclear and four mitochondrial gene regions they were assigned to five of the six known subclades, 2a-c, e and f, of Phytophthora major Clade 2 and the new subclade 2g. The evolutionary history of the Clade appears to have involved the pre-Gondwanan divergence of three extant subclades, 2c, 2e and 2f, all having disjunct natural distributions on separate continents and comprising species with a soilborne and aquatic lifestyle and, in addition, a few partially aerial species in Clade 2c; and the post-Gondwanan evolution of subclades 2a and 2g in Southeast/East Asia and 2b in South America, respectively, from their common ancestor. Species in Clade 2g are soilborne whereas Clade 2b comprises both soil-inhabiting and aerial species. Clade 2a has evolved further towards an aerial lifestyle comprising only species which are predominantly or partially airborne. Based on high nuclear heterozygosity levels ca. 38 % of the taxa in Clades 2a and 2b could be some form of hybrid, and the hybridity may be favoured by an A1/A2 breeding system and an aerial life style. Circumstantial evidence suggests the now 93 described species and informally designated taxa in Clade 2 result from both allopatric non-adaptive and sympatric adaptive radiations. They represent most morphological and physiological characters, breeding systems, lifestyles and forms of host specialism found across the Phytophthora clades as a whole, demonstrating the strong biological cohesiveness of the genus. The finding of 43 previously unknown species from a single Phytophthora clade highlight a critical lack of information on the scale of the unknown pathogen threats to forests and natural ecosystems, underlining the risk of basing plant biosecurity protocols mainly on lists of named organisms. More surveys in natural ecosystems of yet unsurveyed regions in Africa, Asia, Central and South America are needed to unveil the full diversity of the clade and the factors driving diversity, speciation and adaptation in Phytophthora. [ABSTRACT FROM AUTHOR]

Identifying the drivers of microgeographic speciation (i.e. speciation over small, local geographic scales) is key to understand the origin of speciose groups. Here, we use genomic data to infer the demographic processes underlying diversification in Poecilimon luschani (Orthoptera: Tettigoniidae), a species complex belonging to the most diverse genus of bush crickets from the Mediterranean region (>170 taxa) that comprises three recognized subspecies with small allopatric distributions in the topographically complex Teke Peninsula, southwestern Anatolia. Phylogenomic reconstructions that include all other taxa within the species group confirmed that subspecies of P. luschani originated from a common ancestor during the Pleistocene, supporting recent (<1 Ma) diversification within a small geographical area (ca. 120 × 80 km). Genetic clustering analyses corroborated the distinctiveness of each subspecies and the cohesiveness of their respective populations, with abrupt genetic discontinuities coinciding with contemporary range boundaries. Indeed, our analyses uncovered the presence of two sympatric cryptic sister lineages that diverged <300 ka ago and do not admix despite being co-distributed. Collectively, these results support that all lineages within the complex represent independently evolving entities corresponding to full-fledged species. Statistical evaluation of alternative models of speciation strongly supports a scenario of divergence in isolation followed by a period of limited gene flow during the last glacial period, when all lineages experienced marked expansions according to demographic reconstructions. Our study exemplifies how localized allopatric divergence and fast evolution of reproductive isolation can promote microgeographic speciation and explain the high rates of endemism characterizing biodiversity hotspots. [ABSTRACT FROM AUTHOR]

Dianthus virgineus encompasses a very complex taxonomic group (traditionally called D. sylvestris group) including an array of units of doubtful taxonomic rank and value. Recent work identified three genetic lineages within this complex that showed strong genetic isolation, and clear geographical boundaries (i.e., "Alpine", "Balkan", and "Apennine" lineages). We evaluated the contribution of 33 morphological characters in differentiating such genetic units, by also investigating the effect of geographical and ecological drivers on the characters showing major discriminating power. The morphological measures were taken from a large number of populations (N = 97) included in the sample used for detecting the three genetic lineages. Our work reveals that these lineages can be morphologically discriminated by a series of character‐states that are traditionally considered of relevant taxonomical value. We also inferred a significant geographical and ecological effect on most characters, which varied gradually with latitude, longitude, and mean annual temperature. Overall, our data suggest that the three biological units can be referred to D. inodorus (L.) Gaertn. ("Alpine" lineage), D. sylvestris Wulfen ("Balkan" lineage), and D. virgineus L. s.str. ("Apennine" lineage). We also provide an identification key to discriminate these three taxa. [ABSTRACT FROM AUTHOR]

The Kentish Plover Charadrius alexandrinus Linnaeus 1758 is a common shorebird in Eurasia and North Africa that breeds in a variety of habitats, exhibits different extents of migratory behaviour and is an emerging model species of breeding system evolution. Here we focus on the resident population found across the southern tip of India and Sri Lanka, and re‐evaluate its systematic status based on phenotypic and genetic distinctiveness from a sympatric migrant, Charadrius alexandrinus sensu stricto, and the recently elevated closely related Charadrius dealbatus in East Asia. We show that the Sri Lankan and South Indian (South Asian) population differs in body size, moulting pattern and plumage coloration from C. alexandrinus and C. dealbatus. Furthermore, based on two mitochondrial, two sex‐linked and 11 autosomal microsatellite markers from 378 individuals, we show that these three taxa have moderate genetic differentiation (Fst 0.078–0.096). The South Asian taxon is sister to the clade of C. alexandrinussensu stricto and C. dealbatus with an estimated divergence time of 1.19 million years ago. We also examined ornithological records of major museum collections in Asia, Europe and North America for the south Asian taxon to evaluate its biogeographical and taxonomic status. Based on differences in genotype, phenotype, allochronic migratory pattern and breeding range, we resurrect the most suitable synonym, Charadrius alexandrinus seebohmi Hartert and Jackson, 1915, and elevate the nomen to the species level with the proposed English name 'Hanuman Plover'. [ABSTRACT FROM AUTHOR]

Caucasian rock lizards (Darevskia) are a speciose group with 42 described species from the Caucasus Mountain region. We selected 11 species from Georgia and adjacent territories to explore whether their distribution depends on the distribution of congeneric taxa. We estimated two measures for each species pair: (1) niche overlap between all pairs of the studied species; (2) the extent of contact between the ranges of individual species. We then calculated the correlation between these measurements and the time of divergence between the species. The results showed that in sympatric and parapatric (but not allopatric) species, there is a highly significant correlation between the divergence time and the extent of the contact, as well as between the divergence time and the overlap of suitable habitats. The ranges of the evolutionarily closest species have the smallest extent of contact. Species separated later have overlapping ranges, although are separated by altitude. The most distant species, irrespective of their phenotype, are commonly found in the same location. We suggest that a gradual increase in the contact extent is compensated for by increasing the effectiveness of other mechanisms of niche shift or behavioural isolation and hence the frequency of potentially deleterious interspecific contacts is kept low. [ABSTRACT FROM AUTHOR]

The small-eared shrews Cryptotis mexicanus and Cryptotis obscurus (Eulipotyphla, Soricidae) are two closely related taxa from the northern Neotropics whose taxonomy is still unresolved. Here, we tested the hypothesis of three lineages (Northern, Central, and Southern) within this pair of semifossorial shrews. We photographed skulls, dentaries, and humeri from 226 museum specimens and used geometric morphometrics to evaluate sexual dimorphism, differences between lineages, and the effect of the environment on the shape of the structures. We found negligible differences between males and females, supporting previous studies of classical morphometrics in this genus. Our results also support the differentiation of semifossorial shrews into the three geographically isolated groups, where the size of the dentary and the shape of the three examined structures contribute to discrimination. We found a significant sign of the influence of the environment on the shape of the dentary but not on the skull or the humerus. We suggest that geographic isolation across climatically similar regions has contributed to the differentiation between lineages. We propose recognizing all three lineages as valid species that must be adequately described. [ABSTRACT FROM AUTHOR]

Fungi produce a wealth of pharmacologically bioactive secondary metabolites (SMs) from biosynthetic gene clusters (BGCs). It is common practice for drug discovery efforts to treat species' secondary metabolomes as being well represented by a single or a small number of representative genomes. However, this approach misses the possibility that intraspecific population dynamics, such as adaptation to environmental conditions or local microbiomes, may harbor novel BGCs that contribute to the overall niche breadth of species. Using 94 isolates of Aspergillus flavus, a cosmopolitan model fungus, sampled from seven states in the United States, we dereplicate 7,821 BGCs into 92 unique BGCs. We find that more than 25% of pangenomic BGCs show population-specific patterns of presence/absence or protein divergence. Population-specific BGCs make up most of the accessory-genome BGCs, suggesting that different ecological forces that maintain accessory genomes may be partially mediated by population-specific differences in secondary metabolism. We use ultra-high-performance high-resolution mass spectrometry to confirm that these genetic differences in BGCs also result in chemotypic differences in SM production in different populations, which could mediate ecological interactions and be acted on by selection. Thus, our results suggest a paradigm shift that previously unrealized population-level reservoirs of SM diversity may be of significant evolutionary, ecological, and pharmacological importance. Last, we find that several population-specific BGCs from A. flavus are present in Aspergillus parasiticus and Aspergillus minisclerotigenes and discuss how the microevolutionary patterns we uncover inform macroevolutionary inferences and help to align fungal secondary metabolism with existing evolutionary theory.

Abstract Insect speciation is among the most fascinating topics in evolutionary biology; however, its underlying mechanisms remain unclear. Allopatric speciation represents one of the major types of speciation and is believed to have frequently occurred during glaciation periods, when climatic oscillation may have caused suitable habitats to be fragmented repeatedly, creating geographical isolation among populations. However, supporting evidence for allopatric speciation of insects in East Asia during the Pleistocene glaciation remains lacking. We aim to investigate the effect of climatic oscillation during the Pleistocene glaciation on the diversification pattern and evolutionary history of hemipteran insects and to test the hypothesis of Pleistocene species stability using spinous assassin bugs Sclomina (Hemiptera: Reduviidae), a small genus widely distributed in southern China but was later found to have cryptic species diversity. Here, using the whole mitochondrial genome (mitogenome) and nuclear ribosomal RNA genes, we investigated both interspecific and intraspecific diversification patterns of spinous assassin bugs. Approximate Bayesian computation, ecological niche modeling, and demographic history analyses were also applied to understand the diversification process and driven factors. Our data suggest that the five species of Sclomina are highly diverged, despite three of them currently being cryptic. Speciation occurred during the Pleistocene when suitable distribution areas were possibly fragmented. Six phylogeographic groups in the type species S. erinacea were identified, among which two groups underwent expansion during the early Last Glacial Period and after Last Glacier Maximum. Our analyses suggest that this genus may have experienced climate‐driven habitat fragmentation and postglacial expansion in the Pleistocene, promoting allopatric speciation and intraspecific diversification. Our results reveal underestimated species diversity in a small insect group and illustrate a remarkable example of allopatric speciation of insects in East Asia promoted by Pleistocene climatic oscillations. These findings provide important insights into the speciation processes and aid the conservation of insect species diversity.

Simple Summary: The Siberian ibex has a wide distribution, spanning various mountainous regions and cold deserts in countries like India, China, Pakistan, Kazakhstan, Tajikistan, Russia, and Mongolia. Our study specifically examined the Himalayan ibex, which is an edge population of Siberian ibex found in India. Through genomic analysis, we discovered that the Himalayan ibex evolved as a distinct lineage after separating from the main population around 100,000 years ago, due to geographical isolation. By studying the region's past geography using paleo-climatic models and deep sequencing data, we observed significant transformations, including high mountains and deep valleys, particularly in the Pamir range, likely played a significant role in the divergence and independent evolution of the Himalayan ibex, after experiencing two historic genetic bottlenecks. Based on our findings, we propose prioritizing the Himalayan ibex as a unique phylogenetic species and advocate for its conservation attention and taxonomic revision. Furthermore, we hope that our research will inspire collaborative efforts and discussions among different countries to address the conservation and management of ibex populations worldwide. Pleistocene glaciations had profound impact on the spatial distribution and genetic makeup of species in temperate ecosystems. While the glacial period trapped several species into glacial refugia and caused abrupt decline in large populations, the interglacial period facilitated population growth and range expansion leading to allopatric speciation. Here, we analyzed 40 genomes of four species of ibex and found that Himalayan ibex in the Pamir Mountains evolved independently after splitting from its main range about 0.1 mya following the Pleistocene species pump concept. Demographic trajectories showed Himalayan ibex experienced two historic bottlenecks, one each c. 0.8–0.5 mya and c. 50–30 kya, with an intermediate large population expansion c. 0.2–0.16 mya coinciding with Mid-Pleistocene Transitions. We substantiate with multi-dimensional evidence that Himalayan ibex is an evolutionary distinct phylogenetic species of Siberian ibex which need to be prioritized as Capra himalayensis for taxonomic revision and conservation planning at a regional and global scale. [ABSTRACT FROM AUTHOR]

Elucidating how species accumulate in diversity hotspots is an ongoing debate in evolutionary biology. The páramo, in the Northern Andes, has remarkably high indices of plant diversity, endemicity, and diversification rates. A hypothesis for explaining such indices is that allopatric speciation is high in the páramo given its island-like distribution. An alternative hypothesis is that the altitudinal gradient of the Andean topography provides a variety of niches that drive vertical parapatric ecological speciation. A formal test for evaluating the relative roles of allopatric and parapatric ecological speciation is lacking. The main aim of our study is to test which kind of speciation is more common in an endemic páramo genus. We developed a framework incorporating phylogenetics, species' distributions, and a morpho-ecological trait (leaf area) to compare sister species and infer whether allopatric or parapatric ecological divergence caused their speciation. We applied our framework to the species-rich genus Linochilus (63 spp.) and found that the majority of recent speciation events in it (12 events, 80%) have been driven by allopatric speciation, while a smaller fraction (one event, 6.7%) is attributed to parapatric ecological speciation; two pairs of sister species produced inconclusive results (13.3%). We conclude that páramo autochthonous (in-situ) diversification has been primarily driven by allopatric speciation. [ABSTRACT FROM AUTHOR]

The ant genus Myrmecina, whose diversity is mostly concentrated in SE-Asia and Oceania, counts four W-Palearctic species. The extremely euryecious and well-studied Myrmecina graminicola occurs from Iberia to the Caucasus and from the Maghreb to Scandinavia, while three little-known species (M. atlantis, M. melonii and M. sicula) coexist with M. graminicola in their narrow Maghrebian, Sardinian and Sicilian ranges, respectively. Myrmecina sicula has been described about 140 years ago from a single site and two specimens only. Their unique morphology suggested the validity of this taxon ever since, but no additional specimens were found in the following century. We present the results of decades of sampling efforts across Sicily, resulting in the collection of M. graminicola from 70 sites and M. sicula from 13 sites. We confirm M. sicula unique morphological identity and report on the marked distributional and ecological differences between the two species. Myrmecina graminicola is widespread and inhabits diverse, mainly forested habitats from lowland to high mountain sites, while M. sicula was found in a very narrow region of old carbonate platform between NW-Sicily and the Egadi Islands, mostly in sparsely vegetated sites at mid to low-altitude. Reviewing their common morphological and biogeographic traits, we propose to consider M. atlantis, M. melonii and M. sicula as a distinct M. sicula complex, whose identity and history deserves further investigation through molecular analyses.

Insect speciation is among the most fascinating topics in evolutionary biology; however, its underlying mechanisms remain unclear. Allopatric speciation represents one of the major types of speciation and is believed to have frequently occurred during glaciation periods, when climatic oscillation may have caused suitable habitats to be fragmented repeatedly, creating geographical isolation among populations. However, supporting evidence for allopatric speciation of insects in East Asia during the Pleistocene glaciation remains lacking. We aim to investigate the effect of climatic oscillation during the Pleistocene glaciation on the diversification pattern and evolutionary history of hemipteran insects and to test the hypothesis of Pleistocene species stability using spinous assassin bugs Sclomina (Hemiptera: Reduviidae), a small genus widely distributed in southern China but was later found to have cryptic species diversity. Here, using the whole mitochondrial genome (mitogenome) and nuclear ribosomal RNA genes, we investigated both interspecific and intraspecific diversification patterns of spinous assassin bugs. Approximate Bayesian computation, ecological niche modeling, and demographic history analyses were also applied to understand the diversification process and driven factors. Our data suggest that the five species of Sclomina are highly diverged, despite three of them currently being cryptic. Speciation occurred during the Pleistocene when suitable distribution areas were possibly fragmented. Six phylogeographic groups in the type species S. erinacea were identified, among which two groups underwent expansion during the early Last Glacial Period and after Last Glacier Maximum. Our analyses suggest that this genus may have experienced climate‐driven habitat fragmentation and postglacial expansion in the Pleistocene, promoting allopatric speciation and intraspecific diversification. Our results reveal underestimated species diversity in a small insect group and illustrate a remarkable example of allopatric speciation of insects in East Asia promoted by Pleistocene climatic oscillations. These findings provide important insights into the speciation processes and aid the conservation of insect species diversity. [ABSTRACT FROM AUTHOR]

Understanding climatic variables to determine the ecological niche is crucial to explaining species distributions and revealing how sister species coexist within a geographic area. Here, we used ecological niche modeling to determine the ecological niche patterns of two toad species in Türkiye: Bufo bufo and Bufo verrucosissimus. Thus, we tested the ecological niche divergence and similarity between these species. In our results, the potential distribution of B. verrucosissimus showed high suitability throughout all Caucasus hotspots, and this suitability has been found even along the middle and western coast of Türkiye, but suitability was found to be very weak in the southern part of Türkiye. For B. bufo, the distribution pattern indicated high suitability along the Black Sea and Mediterranean coasts of Türkiye, but this suitability was low throughout Caucasus hotspots. Furthermore, we found that among B. bufo and B. verrucosissimus, the niches are not identical, but this situation is different in the background test. Therefore, we suggested that although there is niche conservatism between the two sister species, this pattern is caused by geographic barriers, not climatic parameters. [ABSTRACT FROM AUTHOR]

Under the ecological speciation model, divergent selection acts on ecological differences between populations, gradually creating barriers to gene flow and ultimately leading to reproductive isolation. Hybridisation is part of this continuum and can both promote and inhibit the speciation process. Here, we used white‐tailed (Odocoileus virginianus) and mule deer (O. hemionus) to investigate patterns of speciation in hybridizing sister species. We quantified genome‐wide historical introgression and performed genome scans to look for signatures of four different selection scenarios. Despite ample modern evidence of hybridisation, we found negligible patterns of ancestral introgression and no signatures of divergence with gene flow, rather localized patterns of allopatric and balancing selection were detected across the genome. Genes under balancing selection were related to immunity, MHC and sensory perception of smell, the latter of which is consistent with deer biology. The deficiency of historical gene‐flow suggests that white‐tailed and mule deer were spatially separated during the glaciation cycles of the Pleistocene and genome wide differentiation accrued via genetic drift. Dobzhansky‐Muller incompatibilities and selection against hybrids are hypothesised to be acting, and diversity correlations to recombination rates suggests these sister species are far along the speciation continuum. [ABSTRACT FROM AUTHOR]

It is considered that allopatric speciation proceeds slower than sympatric speciation and rarely results in rapid differentiation of populations. In particular, high intraspecific divergence in fishes from recently glaciated freshwater systems is typically observed within flocks of sympatric forms, not between geographically isolated populations. We present an alternative case of fast and profound eco-morphological and genetic divergence between two allopatric Transbaikalian populations of Arctic charr. In one, charr are predominantly piscivorous with sparse short gill rakers; in the other, predominantly planktivorous with dense long gill rakers. Gill raker number differs with no overlap and there is considerable differentiation in other meristic and morphometric characters. Both populations manifest exceptionally low variability at microsatellite loci coupled with substantial interpopulational differences in allele composition obviously resulting from genetic drift. Still, they form a monophyletic clade in microsatellite phylogenetic tree of Transbaikalian charr and share the same mtDNA control region haplotype, which evidences their common origin. According to genetic dating, the divergence of the populations occurred about 14 thousand years ago. Our study shows that high differentiation between local charr populations can emerge in allopatry over a short time if speciation is driven by trophic specialization and is facilitated by small population sizes. [ABSTRACT FROM AUTHOR]

Elucidating how species accumulate in diversity hotspots is an ongoing debate in evolutionary biology. The páramo, in the Northern Andes, has remarkably high indices of plant diversity, endemicity, and diversification rates. A hypothesis for explaining such indices is that allopatric speciation is high in the páramo given its island-like distribution. An alternative hypothesis is that the altitudinal gradient of the Andean topography provides a variety of niches that drive vertical parapatric ecological speciation. A formal test for evaluating the relative roles of allopatric and parapatric ecological speciation is lacking. The main aim of our study is to test which kind of speciation is more common in an endemic páramo genus. We developed a framework incorporating phylogenetics, species’ distributions, and a morpho-ecological trait (leaf area) to compare sister species and infer whether allopatric or parapatric ecological divergence caused their speciation. We applied our framework to the species-rich genus Linochilus (63 spp.) and found that the majority of recent speciation events in it (12 events, 80%) have been driven by allopatric speciation, while a smaller fraction (one event, 6.7%) is attributed to parapatric ecological speciation; two pairs of sister species produced inconclusive results (13.3%). We conclude that páramo autochthonous (in-situ) diversification has been primarily driven by allopatric speciation.

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Centaurea subsection Phalolepis has been thoroughly analyzed in previous studies using microsatellites in four centers of speciation: Anatolia, Greece, the Italian Peninsula and the Iberian Peninsula. Evidence suggests a correlation between taxon diversity and mountains. This group constituted a good case study for examining the mountain–geobiodiversity hypothesis (MGH), which explains the possible reasons for the many radiations occurring in mountains across the world. We combined all the datasets and carried out analyses of their genetic structure to confirm the species of subsect. Phalolepis are grouped according to a geographic pattern. We then checked whether climatic fluctuations favored the "species pump" hypothesis in the mountains by using the Climatic Stability Index (CSI). Finally, the relief of the terrain was tested against the rate of allopatric speciation by region by means of Terrain Ruggedness Index and environmental gradients through our new Climate Niche Breadth Index. Our results supported the MGH hypothesis and confirmed that the main triggers, namely altitudinal zonation, climatic oscillations and rugged terrain, must be present for the development of a radiation. [ABSTRACT FROM AUTHOR]

Here, we explored how variations in the allopatric speciation scenario, specifically ecological vs. vicariant allopatry, relate to climatic niche change in sister species. We selected two sister species pairs of North American hummingbirds (Calypte anna, C. costae , Basilinna leucotis, B. xantusii) that diverged 2.5 and 3.6 million years ago, under ecological (arid climate tendency during Pliocene) and vicariant (Baja California peninsula separation) allopatric processes, respectively. We constructed the climatic niche of each species using occurrence records and estimated the distance, similarity, and unique fraction of climatic niche between sister species. Calypte species showed moderate niche divergence (Euclidean distance between centroids = 1.94, Sørensen index of similarity = 0.080, unique fraction of hypervolume in C. costae = 0.57, and C. anna = 0.95). However, contrary to expectations, Basilinna species, which diverged under a vicariant scenario, displayed clear niche divergence (Euclidean distance between centroids = 3.78, Sørensen index of similarity = 0.0001, and unique fraction of hypervolume in B. xantusii = 0.98, and B. leucotis = 0.99). We explained dissimilarity in climatic niches between Basilinna species by the ecological divergence between habitats of disjunct populations, which would have also been associated with increased aridity during the Pliocene. [Display omitted] • Type of allopatry affects the degree of niche conservatism in the speciation process. • We tested it in hummingbirds speciation under geographical and ecological allopatry. • Soft ecological allopatry in Calypte species led to expected niche divergence. • Hard geographical allopatry in Basilinna species led to unexpected niche divergence. • Environmental changes in the Pliocene and niche truncation may explain these patterns. [ABSTRACT FROM AUTHOR]

The Cape Floristic Region in the Republic of South Africa is a well‐recognized hotspot of biodiversity. Although this region is mostly known for its high level of plant diversity and endemicity, it also hosts an understudied and likely diverse arthropod fauna. Here we investigate the evolutionary history and timing of diversification of the apterous weevil genus Phlyctinus (Curculionidae: Entiminae), which is endemic to the coastal area and adjacent mountain ranges of the Cape floristic region and generally associated with sunflower plants (Asteraceae). We use a diverse array of molecular analyses (phylogenetic inference, molecular species delimitation and dating analyses) to analyse a novel molecular dataset of 202 weevil specimens (including 170 Phlyctinus sampled in 60 sites), and sequenced for two mitochondrial and four nuclear gene fragments. Phylogenetic and dating analyses indicate that the genus started diversifying in the late Miocene, with contrasting diversification dynamics for the three inferred clades, which present disjunct distributions. Host plant records and the lack of relatedness of species living in sympatry indicate that the diversification of Phlyctinus was predominantly driven by allopatric (geographic) speciation. We hypothesize that the interplay between topography and recurring cycles of coastline‐habitat fragmentation resulting from sea level oscillations spurred the diversification of the most speciose clade, whereas in the two remaining clades populations likely remained connected thus hampering allopatric speciation. Interestingly, this pattern echoes with the role of sea level oscillations as an important driver of the radiation of several lineages in the coastline ecosystems of the Cape Floristic Region. [ABSTRACT FROM AUTHOR]

Grusonia is an opuntioid genus in the Cylindropuntieae, Cactaceae, endemic to the North American deserts in Mexico and the United States. The monophyletic status of the genus and the degrees of endemicity of its species make Grusonia a suitable study group in order to test biogeographic hypotheses such as vicariant or dispersal events, biogeographic barriers and time‐calibrated phylogenies in order to propose speciation events in the group. The statistical dispersal‐vicariance analysis (S‐DIVA) and a statistical dispersal‐local extinction‐cladogenesis (S‐DEC) analyses show general congruence postulating ancestral ranges for the species of Grusonia. They disagree, however, in a clade with four species from the Sonoran Desert, the Baja California Peninsula and one species endemic to the central portion of the Chihuahuan Desert Region. The time‐calibrated phylogeny here proposed shows an average age of 3.7 Ma for the genus. Grusonia has two internal clades comprising species most likely generated by allopatric speciation under a vicariant scenario. The results of this study support a young age for the North American deserts and identify the end of the Pliocene and mainly the Plio‐Pleistocene boundary as the starting point of the cladogenetic events that gave rise to the two main clades of Grusonia. [ABSTRACT FROM AUTHOR]

Numerous temperate plants and animals on the Qinghai-Tibet Plateau (QTP) are hypothesized to have differentiated due to vicariant allopatric speciation associated with the geologic uplifts. However, this hypothesis has rarely been tested through a phylogeographic study of relative species in a broader geographic context, including the QTP, Tianshan Mountains, Mongolian Plateau, and surrounding regions. To understand the speciation and diversification process of plants across this wide area, phylogeographic analysis were examined from Scrophularia incisa and two other closely relative species comprising S. kiriloviana and S. dentata. Thirty-two populations of the three close relatives were genotyped using chloroplast DNA fragments and nuclear microsatellite loci to assess population structure and diversity, supplemented by phylogenetic dating, ancestral area reconstructions and species distribution modelings, as well as niche identity tests. Our chloroplast DNA (cpDNA) phylogeny showed that this monophyletic group of desert and steppe semi-shrub is derived from a Middle Pliocene ancestor of the Central Asia. Lineages in Central Asia vs. China diverged through climate/tectonicinduced vicariance during Middle Pliocene. Genetic and ENM data in conjunction with niche differentiation analyses support that the divergence of S. incisa, S. dentata and S. kiriloviana in China lineage proceeded through allopatric speciation, might triggered by early Pleistocene climate change of increase of aridification and enlargement of deserts, while subsequent climate-induced cycles of range contractions/expansions enhanced the geographical isolation and habit fragmentation of these taxa. These findings highlight the importance of the Plio-Pleistocene climate change in shaping genetic diversity and driving speciation in temperate steppes and deserts of Northwestern China. [ABSTRACT FROM AUTHOR]

Pleistocene glaciations had profound impact on the spatial distribution and genetic makeup of species in temperate ecosystems. While the glacial period trapped several species into glacial refugia and caused abrupt decline in large populations, the interglacial period facilitated population growth and range expansion leading to allopatric speciation. Here, we analyzed 40 genomes of four species of ibex and found that Himalayan ibex in the Pamir Mountains evolved independently after splitting from its main range about 0.1 mya following the Pleistocene species pump concept. Demographic trajectories showed Himalayan ibex experienced two historic bottlenecks, one each c. 0.8–0.5 mya and c. 50–30 kya, with an intermediate large population expansion c. 0.2–0.16 mya coinciding with Mid-Pleistocene Transitions. We substantiate with multi-dimensional evidence that Himalayan ibex is an evolutionary distinct phylogenetic species of Siberian ibex which need to be prioritized as Capra himalayensis for taxonomic revision and conservation planning at a regional and global scale.

Quaternary climate fluctuations can affect speciation in regional biodiversity assembly in two non-mutually exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation in underused adaptive zones during ice-free periods. We detected biogeographic and genetic signatures associated with both mechanisms in the assembly of the biota of the European Alps. Age distributions of endemic and widespread species within aquatic and terrestrial taxa (amphipods, fishes, amphibians, butterflies and flowering plants) revealed that endemic fish evolved only in lakes, are highly sympatric, and mainly of Holocene age, consistent with adaptive radiation. Endemic amphipods are ancient, suggesting preglacial radiation with limited range expansion and local Pleistocene survival, perhaps facilitated by a groundwater-dwelling lifestyle. Terrestrial endemics are mostly of Pleistocene age and are thus more consistent with the glacial species pump. The lack of evidence for Holocene adaptive radiation in the terrestrial biome is consistent with faster recolonization through range expansion of these taxa after glacial retreats. More stable and less seasonal ecological conditions in lakes during the Holocene may also have contributed to Holocene speciation in lakes. The high proportion of young, endemic species makes the Alpine biota vulnerable to climate change, but the mechanisms and consequences of species loss will likely differ between biomes because of their distinct evolutionary histories. [ABSTRACT FROM AUTHOR]

Background: Hynobius hirosei is a lotic-breeding salamander endemic to Shikoku Island in western Japan. Significant allozymic and morphological differences have been found among the populations of this species; however, the degree and pattern of intraspecific variation have not been surveyed using a sufficient number of samples. Methods: For the taxonomic revision of H. hirosei, we conducted genetic and morphological surveys using samples collected throughout the distribution. Phylogenetic analysis using the cytochrome b region of mitochondrial DNA and population structure analysis using single nucleotide polymorphisms were conducted to evaluate the population structure within the species and the degree of genetic differentiation. Subsequently, a morphological survey based on multivariate and univariate analyses was performed to assess the morphological variation. Results: Genetic analyses revealed three genetic groups (Tsurugi, Central, and Nanyo) within H. hirosei, with the Nanyo group distributed allopatrically from the others, and the Tsurugi and Central groups distributed parapatrically with the formation of a hybrid zone between them. The Nanyo group was morphologically distinguishable from the remaining samples, including the topotype of H. hirosei, based on a smaller body size and several ratio values of characters to snout-vent length, longer axilla-groin distance, shorter tail length, shorter internarial distance, longer upper eyelid length, and larger medial tail width. These results support the notion that the Nanyo group is an undescribed species. However, the remaining genetically differentiated groups could not be divided in the present study. Herein, we described the Nanyo group as a new species. [ABSTRACT FROM AUTHOR]

Freshwater fishes are notably diverse, given that freshwater habitat represents a tiny fraction of the earth's surface, but the mechanisms generating this diversity remain poorly understood. Rivers provide excellent models to understand how freshwater diversity is generated and maintained across heterogeneous habitats. In particular, the lower Congo River (LCR) consists of a dynamic hydroscape exhibiting extraordinary aquatic biodiversity, endemicity, morphological and ecological specialization. Previous studies have suggested that the numerous high‐energy rapids throughout the LCR form physical barriers to gene flow, thus facilitating diversification and speciation, generating ichthyofaunal diversity. However, this hypothesis has not been fully explored using genome‐wide SNPs for fish species distributed across the LCR. Here, we examined four lamprologine cichlids endemic to the LCR that are distributed along the river without range overlap. Using genome‐wide SNP data, we tested the hypotheses that high‐energy rapids serve as physical barriers to gene flow that generate genetic divergence at interspecific and intraspecific levels, and that gene flow occurs primarily in a downstream direction. Our results are consistent with the prediction that powerful rapids sometimes act as a barrier to gene flow but also suggest that, at certain temporal and spatial scales, they may provide multidirectional dispersal opportunities for riverine rheophilic cichlid fishes. These results highlight the complexity of diversification processes in rivers and the importance of assessing such processes across different riverscapes. [ABSTRACT FROM AUTHOR]

Unraveling geographical modes of speciation processes has been a longstanding topic in biogeography. Divergence can be driven by factors operating on multiple spatial scales, such as geographical distance (isolation by distance, IBD), landscape resistance (isolation by resistance, IBR) and environmental heterogeneity (isolation by environment, IBE). However, it is challenging to assess the relative contributions of such factors, which are usually autocorrelated with each other. On the basis of ~294 K nuclear single‐nucleotide polymorphisms from 53 samples, we integrated population genomics, geographical information and environmental variables to delineate genetic differentiation in the common pheasant Phasianus colchicus across a longitudinal gradient in northern China. Generalized dissimilarity modeling (GDM) was used to analyze the relative importance of IBD, IBR and IBE. We found that the common pheasant in northern China was grouped into six genetic clusters, which was consistent with the taxonomic affinities. Genetic diversity changed along the longitudinal gradient, reaching its lowest level at the eastern edge of the Qinghai–Tibetan Plateau (QTP). The spatial pattern of gene flow suggested that the mountains surrounding the QTP and the mountains in central China have acted as geographical barriers impeding common pheasant dispersal. GDM analysis indicated that environmental heterogeneity is the most important driver explaining the lineage divergence, which supports the IBE model. These results suggest that multiple isolation mechanisms shaped genetic diversity and genomic divergence in this wide‐ranging bird species. Together, our results underscore the importance of leveraging genome‐wide variations and ecological modeling to facilitate a deeper understanding of population divergence processes. [ABSTRACT FROM AUTHOR]

Independent evolutionary lineages or species that lack phenotypic variation as an operative criterion for their delimitation are known as cryptic species. However, these have been delimited using other data sources and analysis. The aims of this study are: (1) to evaluate the divergence of the populations of the T. ionantha complex; and (2) to delimit the species using multilocus data, phylogenetic analysis and the coalescent model. Phylogenetic analyses, genetic diversity and population structure, and isolation by distance analysis were performed. A multispecies coalescent analysis to delimit the species was conducted. Phylogenetic analysis showed that T. ionantha is polyphyletic composed of eight evolutionary lineages. Haplotype distribution and genetic differentiation analysis detected strong population structure and high values of genetic differentiation among populations. The positive correlation between genetic differences with geographic distance indicate that the populations are evolving under the model of isolation by distance. The coalescent multispecies analysis performed with starBEAST supports the recognition of eight lineages as different species. Only three out of the eight species have morphological characters good enough to recognize them as different species, while five of them are cryptic species. Tillandsia scaposa and T. vanhyningii are corroborated as independent lineages, and T. ionantha var. stricta changed status to the species level. [ABSTRACT FROM AUTHOR]

Abstract Background The orogeny of the eastern Mediterranean region has substantially affected ecological speciation patterns, particularly of mountain-dwelling species. Mountain vipers of the genus Montivipera are among the paramount examples of Mediterranean neo-endemism, with restricted ranges in the mountains of Anatolia, the Levant, Caucasus, Alborz, and Zagros. Here we explore the phylogenetic and ecological diversification of Montivipera to reconstruct its ecological niche evolution and biogeographic history. Using 177 sequences of three mitochondrial genes, a dated molecular phylogeny of mountain vipers was reconstructed. Based on 320 occurrence points within the entire range of the genus and six climatic variables, ecological niches were modelled and used to infer ancestral niche occupancy. In addition, the biogeographic history and ancestral states of the species were reconstructed across climate gradients. Results Dated phylogenetic reconstruction revealed that the ancestor of mountain vipers split into two major clades at around 12.18 Mya followed by multiple vicariance events due to rapid orogeny. Montivipera colonised coastal regions from a mountain-dwelling ancestor. We detected a highly complex ecological niche evolution of mountain vipers to temperature seasonality, a variable that also showed a strong phylogenetic signal and high contribution in niche occupation. Conclusion Raising mountain belts in the Eastern Mediterranean region and subsequent remarkable changes in temperature seasonality have led to the formation of important centres of diversification and endemism in this biodiversity hotspot. High rates of niche conservatism, low genetic diversity, and segregation of ranges into the endemic distribution negatively influenced the adaptive capacity of mountain vipers. We suggest that these species should be considered as evolutionary significant units and priority species for conservation in Mediterranean mountain ecosystems.

Background Hynobius hirosei is a lotic-breeding salamander endemic to Shikoku Island in western Japan. Significant allozymic and morphological differences have been found among the populations of this species; however, the degree and pattern of intraspecific variation have not been surveyed using a sufficient number of samples. Methods For the taxonomic revision of H. hirosei, we conducted genetic and morphological surveys using samples collected throughout the distribution. Phylogenetic analysis using the cytochrome b region of mitochondrial DNA and population structure analysis using single nucleotide polymorphisms were conducted to evaluate the population structure within the species and the degree of genetic differentiation. Subsequently, a morphological survey based on multivariate and univariate analyses was performed to assess the morphological variation. Results Genetic analyses revealed three genetic groups (Tsurugi, Central, and Nanyo) within H. hirosei, with the Nanyo group distributed allopatrically from the others, and the Tsurugi and Central groups distributed parapatrically with the formation of a hybrid zone between them. The Nanyo group was morphologically distinguishable from the remaining samples, including the topotype of H. hirosei, based on a smaller body size and several ratio values of characters to snout-vent length, longer axilla-groin distance, shorter tail length, shorter internarial distance, longer upper eyelid length, and larger medial tail width. These results support the notion that the Nanyo group is an undescribed species. However, the remaining genetically differentiated groups could not be divided in the present study. Herein, we described the Nanyo group as a new species.

Unraveling geographical modes of speciation processes has been a longstanding topic in biogeography. Divergence can be driven by factors operating on multiple spatial scales, such as geographical distance (isolation by distance, IBD), landscape resistance (isolation by resistance, IBR) and environmental heterogeneity (isolation by environment, IBE). However, it is challenging to assess the relative contributions of such factors, which are usually autocorrelated with each other. On the basis of ~294 K nuclear single‐nucleotide polymorphisms from 53 samples, we integrated population genomics, geographical information and environmental variables to delineate genetic differentiation in the common pheasant Phasianus colchicus across a longitudinal gradient in northern China. Generalized dissimilarity modeling (GDM) was used to analyze the relative importance of IBD, IBR and IBE. We found that the common pheasant in northern China was grouped into six genetic clusters, which was consistent with the taxonomic affinities. Genetic diversity changed along the longitudinal gradient, reaching its lowest level at the eastern edge of the Qinghai–Tibetan Plateau (QTP). The spatial pattern of gene flow suggested that the mountains surrounding the QTP and the mountains in central China have acted as geographical barriers impeding common pheasant dispersal. GDM analysis indicated that environmental heterogeneity is the most important driver explaining the lineage divergence, which supports the IBE model. These results suggest that multiple isolation mechanisms shaped genetic diversity and genomic divergence in this wide‐ranging bird species. Together, our results underscore the importance of leveraging genome‐wide variations and ecological modeling to facilitate a deeper understanding of population divergence processes.

Abstract Background Understanding how species diversify is a long-standing question in biology. The allopatric speciation model is a classic hypothesis to explain the speciation process. This model supposes that there is no gene flow during the divergence process of geographically isolated populations. On the contrary, the speciation with gene flow model supposes that gene flow does occur during the speciation process. Whether allopatric species have gene flow during the speciation process is still an open question. Methods We used the genetic information from 31 loci of 24 Chinese Bamboo Partridges (Bambusicola thoracicus) and 23 Taiwan Bamboo Partridges (B. sonorivox) to infer the gene flow model of the two species, using the approximate Bayesian computation (ABC) model. The ecological niche model was used to infer the paleo-distribution during the glacial period. We also tested whether the two species had a conserved ecological niche by means of a background similarity test. Results The genetic data suggested that the post-divergence gene flow between the two species was terminated before the mid-Pleistocene. Furthermore, our ecological niche modeling suggested that their ecological niches were highly conserved, and that they shared an overlapping potential distribution range in the last glacial maximum. Conclusions The allopatric speciation model cannot explain the speciation process of the two Bamboo Partridges. The results of this study supported a scenario in which speciation with gene flow occurring between the allopatric species and have contributed to our understanding of the speciation process.

The catfish family Heptapteridae, endemic in the Neotropical region, is composed of small- to medium-sized species. The genus Mastiglanis was monotypic until very recently and is often misidentified as Imparfinis because of similarities in diagnostic characters, including the length of maxillary barbels and limited pigmentation. We provide the first molecular inference of diversity for samples identified as Mastiglanis. Partial 16S and COI sequences were produced for 84 samples identified morphologically as Mastiglanis from the Amazon, Orinoco and Essequibo river basins. Species delimitation and phylogenetic methods recovered the genus as monophyletic, but samples assigned to the species Mastiglanis asopos yielded 21 distinct operational taxonomic units, often in sympatry. The first cladogenesis event, at ~12 Mya, was associated with marine incursions and/or vicariance events between the northward-flowing systems in the west and the rivers that drain to the east. Subsequent diversification during the Miocene and Pliocene was inferred to have resulted from environmental changes associated with Andean orogeny, whereas recent diversification in the late Pliocene and Pleistocene was inferred to result from environmental changes during glacial cycles. Despite the many probable cryptic species found across the large geographical distribution of the genus, further sampling is expected to increase taxonomic richness in this genus. [ABSTRACT FROM AUTHOR]

Species diversity may be underestimated even in well-explored mountain regions due to the lack of in-depth research in taxonomically intricate groups. Filling such knowledge gap is necessary to optimize conservation management, specially for species occurring in vulnerable ecosystems such as Southern European mountains. Campanula sect. Heterophylla is a complex group with a high proportion of endemic taxa in European mountain ranges, and whose species delineation is often controversial due to extensive morphological variation. We investigated the phylogenetic relationships and evolutionary entity of its taxa occurring in the Pyrenees, with a special focus on the Pyrenean endemic C. jaubertiana (which is sometimes included as a subspecies of or merged with C. cochleariifolia); and C. andorrana, a taxon allegedly endemic to Andorra (Eastern Pyrenees) and of uncertain taxonomic value. We obtained chloroplast genome and nuclear ribosomal DNA sequences, including several individuals of the three focus taxa, and conducted morphometric analyses. Phylogenetic analyses show that C. jaubertiana sensu lato (s. l.; i.e. including C. andorrana) constitutes a clearly distinct lineage that is not even closely related to C. cochleariifolia; consistent differences in floral morphology were detected between them. Our results support two main evolutionary lineages within C. jaubertiana s. l., one corresponding to populations in Central Pyrenees, and another one in Eastern Pyrenees plus Catalan Pre-Pyrenees. Given the degree of genetic and morphological differentiation, we propose the species rank for each lineage (C. jaubertiana and C. andorrana, respectively) and provide a taxonomic treatment. These two Pyrenean endemics likely diverged through transverse allopatric speciation. [ABSTRACT FROM AUTHOR]

The Macrhybopsis aestivalis complex (nine recognized species of small-bodied, riverine cyprinids) is predicted to have diversified allopatrically in response to prehistoric reorganizations of rivers tributary to the Gulf of México. To flesh out details of this hypothesis, we derived, from previous work, a mitochondrial (ND2) chronogram for interpretation against the background of a published nuclear gene phylogeny (S7 intron 1), paleo-geomorphology, and other species with congruent biogeographies. The complex arose in the Early Miocene and potentially occupied most of its present range by Late Miocene-Early Pliocene. Biogeography is largely consistent with allopatric speciation and secondary contact driven by Neogene river-course rearrangements. One exceptional case of ecologically driven speciation is indicated for an undescribed form in the Ohio River drainage. Heterospecific mtDNA fixation is indicated in the Arkansas and Red rivers as well as in a case of ancient exchange involving M. meeki or M. gelida from outside the complex. A novel result is the suggestion that interspecific mtDNA sharing can exist over millions of years before donor and recipient lineages start to diverge mitochondrially. Additional study is needed to fully resolve the phylogeography of the complex, especially in the Wabash River, Upper Tennessee River, and the southern Mississippi Embayment. Finally, biogeographic considerations and critique of a prior, morphologically based revision of the M. aestivalis complex indicate a need to revisit the synonymy of presently unrecognized M. sterletus with M. aestivalis in the Río Grande drainage. Hypotheses presented are potentially applicable to biogeographies of other riverine fishes. [ABSTRACT FROM AUTHOR]

In evolutionary biology, speciation is often perceived as a gradual evolutionary process spanning thousands of generations; however, the emergence of the London Underground mosquito (Culex pipiens molestus) from the common house mosquito (Culex pipiens) illustrates a recent, observable speciation event. Via allopatric speciation, the mosquito population in London’s underground railway system evolved distinct behavioural and physiological characteristics, becoming isolated and successful in its unique underground environment. The two mosquito species are significantly genetically distinct, and various reproductive barriers exist between them. The London Underground mosquito demonstrates a rapid speciation event that occurred over only a few decades and is a strong model of evolution. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)