Parapatric Distribution Research Articles

Genetic, phenotypic and ecological differentiation suggests incipient speciation in two Charadrius plovers along the Chinese coast

BackgroundSpeciation with gene flow is an alternative to the nascence of new taxa in strict allopatric separation. Indeed, many taxa have parapatric distributions at present. It is often unclear if these are secondary contacts, e.g. caused by past glaciation cycles or the manifestation of speciation with gene flow, which hampers our understanding of how different forces drive diversification. Here we studied genetic, phenotypic and ecological aspects of divergence in a pair of incipient shorebird species, the Kentish (Charadrius alexandrinus) and the White-faced Plovers (C. dealbatus), shorebirds with parapatric breeding ranges along the Chinese coast. We assessed divergence based on molecular markers with different modes of inheritance and quantified phenotypic and ecological divergence in aspects of morphometric, dietary and climatic niches.ResultsOur integrative analyses revealed small to moderate levels of genetic and phenotypic distinctiveness with symmetric gene flow across the contact area at the Chinese coast. The two species diverged approximately half a million years ago in dynamic isolation with secondary contact occurring due to cycling sea level changes between the Eastern and Southern China Sea in the mid-late Pleistocene. We found evidence of character displacement and ecological niche differentiation between the two species, invoking the role of selection in facilitating divergence despite gene flow.ConclusionThese findings imply that ecology can indeed counter gene flow through divergent selection and thus contributes to incipient speciation in these plovers. Furthermore, our study highlights the importance of using integrative datasets to reveal the evolutionary history and assist the inference of mechanisms of speciation.

Multiple radiations of spiny mice (Rodentia: Acomys) in dry open habitats of Afro-Arabia: evidence from a multi-locus phylogeny

BackgroundSpiny mice of the genus Acomys are distributed mainly in dry open habitats in Africa and the Middle East, and they are widely used as model taxa for various biological disciplines (e.g. ecology, physiology and evolutionary biology). Despite their importance, large distribution and abundance in local communities, the phylogeny and the species limits in the genus are poorly resolved, and this is especially true for sub-Saharan taxa. The main aims of this study are (1) to reconstruct phylogenetic relationships of Acomys based on the largest available multilocus dataset (700 genotyped individuals from 282 localities), (2) to identify the main biogeographical divides in the distribution of Acomys diversity in dry open habitats in Afro-Arabia, (3) to reconstruct the historical biogeography of the genus, and finally (4) to estimate the species richness of the genus by application of the phylogenetic species concept.ResultsThe multilocus phylogeny based on four genetic markers shows presence of five major groups of Acomys called here subspinosus, spinosissimus, russatus, wilsoni and cahirinus groups. Three of these major groups (spinosissimus, wilsoni and cahirinus) are further sub-structured to phylogenetic lineages with predominantly parapatric distributions. Combination of alternative species delimitation methods suggests the existence of 26 molecular operational taxonomic units (MOTUs), potentially corresponding to separate species. The highest genetic diversity was found in Eastern Africa. The origin of the genus Acomys is dated to late Miocene (ca. 8.7 Ma), when the first split occurred between spiny mice of eastern (Somali-Masai) and south-eastern (Zambezian) savannas. Further diversification, mostly in Plio-Pleistocene, and the current distribution of Acomys were influenced by the interplay of global climatic factors (e.g., Messinian salinity crisis, intensification of Northern Hemisphere glaciation) with local geomorphology (mountain chains, aridity belts, water bodies). Combination of divergence dating, species distribution modelling and historical biogeography analysis suggests repeated “out-of-East-Africa” dispersal events into western Africa, the Mediterranean region and Arabia.ConclusionsThe genus Acomys is very suitable model for historical phylogeographic and biogeographic reconstructions of dry non-forested environments in Afro-Arabia. We provide the most thorough phylogenetic reconstruction of the genus and identify major factors that influenced its evolutionary history since the late Miocene. We also highlight the urgent need of integrative taxonomic revision of east African taxa.

Triturus newts

Ben Wielstra introduces Eurasian newts of the genus Triturus.

The niches of nuthatches affect their lineage evolution differently across latitude

Ecological niche evolution can promote or hinder the differentiation of taxa and determine their distribution. Niche-mediated evolution may differ among climatic regimes, and thus, species that occur across a wide latitudinal range offer a chance to test these heterogeneous evolutionary processes. In this study, we examine (a) how many lineages have evolved across the continent-wide range of the Eurasian nuthatch (Sitta europaea), (b) whether the lineages' niches are significantly divergent or conserved and (c) how their niche evolution explains their geographic distribution. Phylogenetic reconstruction and ecological niche models (ENMs) showed that the Eurasian nuthatch contained six parapatric lineages that diverged within 2Myr and did not share identical climatic niches. However, the niche discrepancy between these distinct lineages was relatively conserved compared with the environmental differences between their ranges and thus was unlikely to drive lineage divergence. The ENMs of southern lineages tended to cross-predict with their neighbouring lineages whereas those of northern lineages generally matched with their abutting ranges. The coalescence-based analyses revealed more stable populations for the southern lineages than the northern ones during the last glaciation cycle. In contrast to the overlapping ENMs, the smaller parapatric distribution suggests that the southern lineages might have experienced competitive exclusion to prevent them from becoming sympatric. On the other hand, the northern lineages have expanded their ranges and their current abutting distribution might have resulted from lineages adapting to different climatic conditions in allopatry. This study suggests that niche evolution may affect lineage distribution in different ways across latitude.

Interspecific aggression among parapatric and sympatric songbirds on a tropical elevational gradient

Abstract Interspecific competition is hypothesized to be a strong force that sets species range limits and drives parapatric distributions of closely related species on tropical mountains. Yet, experimental evidence that competition drives spatial segregation of closely related species on elevational gradients is rare. To test whether competition limits elevational ranges of tropical songbirds, we conducted reciprocal playback experiments on 2 pairs of species with adjacent but nonoverlapping (parapatric) distributions and 1 pair of sympatric species. We found asymmetric interspecific aggression in one parapatric pair (Pycnonotidae) and a complete absence of interspecific aggression in the other (Zosteropidae). We also found asymmetric interspecies aggression in a pair of sympatric flycatchers (Muscicapidae). Our results indicate that interspecific aggression may set range limits in some cases, but it is not a prerequisite for parapatry. Furthermore, the presence of interspecific aggression between co-occurring relatives suggests that while competition may play a role in limiting species distributions, interspecific aggression alone is not sufficient evidence to assert that competition is the primary driver of parapatric distributions.

Phylogeography of lethal male fighting in a social spider mite.

When males fight for access to females, such conflict rarely escalates into lethal fight because the risks and costs involved, that is, severe injury or death, are too high. The social spider mite, Stigmaeopsis miscanthi, does exhibit lethal male fights, and this male–male aggressiveness varies among populations. To understand the evolution of lethal fighting, we investigated aggressiveness in 42 populations and phylogenetic relationships in 47 populations along the Japanese archipelago. By analysis of the male weapon morph, a proxy for aggressiveness, we confirmed the existence of a mildly aggressive (ML) form, besides the low aggression (LW) and high aggression (HG) forms reported earlier. To evaluate demographic history of these three forms, we employed the approximate Bayesian computation approach using mtCOI sequences and taking into consideration the postlast glacial expansion history of the host plant, Miscanthus sinensis. As results, hierarchical split models are more likely to explain the observed genetic pattern than admixture models, and the ML form in the subtropical region was considered the ancestral group. The inferred demographic history was consistent with the one reconstructed for the host plant in a previous study. The LW form was split from the ML form during the last glacial period (20,000–40,000 years BP), and subsequently, the HG form was split from the ML form at the end of or after the last glacial period (5,494–10,988 years BP). The results also suggest that the mite invaded Japan more than once, resulting in the present parapatric distribution of LW and HG forms in eastern Japan.

Climate change is likely to affect the distribution but not parapatry of the Brazilian marmoset monkeys (Callithrix spp.)

AbstractAimParapatric distributional patterns can arise from abiotic or biotic factors, or from dispersal barriers. Climate change can potentially affect parapatry by changing species’ potential geographic distribution, and thereby widening or shrinking contact zones. Here, we study the effects of climate change on all six species in the genus Callithrix, a group of small‐sized Neotropical primates that is distributed parapatrically in eastern Brazil, allegedly due to biotic interactions.LocationAtlantic Forest, savanna and xeric shrublands from Brazil.MethodsWe explore a method to investigate potential effects of climate change on the distribution of parapatric species by (a) determining whether the parapatric pattern is explained by abiotic (climate) or biotic (species’ interactions) factors using niche equivalency and niche similarity tests; (b) estimating each species’ potential distribution under current and future climatic conditions, using ecological niche models; and (c) performing a pixel‐by‐pixel analysis in order to constrain distribution overlap between species pairs in which parapatry is maintained by biotic factors.ResultsWe found that parapatry in Callithrix is maintained mostly by abiotic factors, except for two species pairs (Callithrix aurita vs. C. flaviceps and C. geoffroyi vs. C. penicillata) in which biotic factors are more likely to be acting. Our proposed method is able to produce better models than conventional ecological niche modelling, predicting net reductions in distribution area for some species and increases for others; however, reductions generally exceeded expansions. The reduction in potential distribution areas would maintain Callithrix flaviceps as Endangered under IUCN criteria.Main conclusionsDespite range contractions and the loss of area of sympatry, climate change is unlikely to affect the parapatric distribution patterns in Callithrix, nor intensify interspecific interactions.

Differentiation underground: Range-wide multilocus genetic structure of the silvery mole-rat does not support current taxonomy based on mitochondrial sequences

The silvery mole-rat (Heliophobius argenteocinereus) is a solitary subterranean rodent with its distribution centred mainly in miombo woodlands of eastern Africa. This part of the continent was significantly influenced by the formation of the East African Rift System (EARS) during the last 25 Mya and by pronounced climatic changes in the Plio-Pleistocene that have caused genetic differentiation leading even to speciation events in many organisms. Recently, based on analysis of mitochondrial (mt) DNA sequences, it was suggested that H. argenteocinereus is a complex of six to eight species that diverged from the early to middle Miocene. In the present study, we significantly extended the sampling, re-analysed mtDNA datasets and analysed nuclear markers with the aim to assess the evolutionary history of Heliophobius. If we do not consider the old museum samples from south-eastern Democratic Republic of Congo (very divergent short mtDNA sequences obtained from ancient DNA, requiring further study from fresh material), the genus Heliophobius is composed of three major mtDNA lineages with parapatric distribution. The Rukwa Rift (+Mbeya triple junction) at the Zambia-Tanzania border, Lake Malawi, and the Eastern Arc Mountains form the biogeographical divides among these clades. The relatively shallow differences among the mitochondrial clades, divergence dating based on the use of the fossilised birth-death ratio model and a multi-locus dataset, and a very similar pattern of genetic structure to other rodents inhabiting the same area and habitat, suggest that the evolutionary history of the extant silvery mole-rat was predominantly influenced by the climatic fluctuations in the Plio-Pleistocene. Awaiting further studies employing genomic, ecological, morphological or behavioural data, we advocate for using the single name H. argenteocinereus for all evolutionary lineages within this taxon, because (1) comparison of the genetic structure observed in mtDNA and nuclear markers suggest hybridization between at least some mtDNA lineages in the contact zones; and (2) new samples close to the type localities suggest incorrect use of previous names.

Phenotypic, Genetic, and Cytogenetic Evidence of Hybridization Between Species of Trans-Andean Tamarins (Genus Saguinus)

Incomplete reproductive isolation and hybridization is relatively frequent in primates. However, no cases of hybridization between formally recognized species have been reported in tamarins (genus Saguinus), a highly specious group of Neotropical primates. Here, we provide evidence from different sources to demonstrate three cases of hybridization in captivity between species of Saguinus distributed west of the Andes (trans-Andean). To do this, we described fur color patterns, genotyped 12 microsatellite loci, sequenced the mitochondrial hypervariable region I, and generated chromosomal R bands for the three formally recognized species and the new hybrids of trans-Andean tamarins. We identified one case of interbreeding between the white-footed tamarin (Saguinus leucopus) and the cotton-top tamarin (S. œdipus) and two independent reciprocal crosses of S. leucopus and the Geoffroy’s tamarin (S. geoffroyi). All these hybrids exhibit intermediate phenotypes between parental species, and genetic data are consistent with first-generation hybridization. Cytogenetic data suggest that the S. leucopus × S. œdipus hybrid is sterile, as it is a female with XY karyotype apparently affected by a condition known as gonadal dysgenesis. Trans-Andean tamarin species occur in northwest Colombia with parapatric distributions bounded by major rivers. Potential contact zones, either natural or anthropogenic, might facilitate hybridization in the wild, but this scenario remains to be assessed. Our findings warrant future studies focused on the evolutionary mechanisms of reproductive isolation in tamarins. Given the risk of hybridization, caution should be taken in management and conservation of tamarins.

Multi-locus phylogeny of southern African Acontias aurantiacus (Peters) subspecies (Scincidae: Acontinae) confirms the presence of three genetically, geographically and morphologically discrete taxa.

Acontias aurantiacus (Peters) presently consists of five subspecies that are largely restricted to the coastal regions and offshore islands of Mozambique and northern South Africa, with subspecies being defined on the basis of morphological differences and/or parapatric distributions. In this study one nuclear (RAG1) and two mitochondrial (cyt b and 16S) genes of 30 individuals sampled from four Mozambican and five South African localities were used to assess the taxonomic relationships of three mainland A. aurantiacus subspecies. Our analyses suggest that A. aurantiacus is a species complex that is sister to A. bicolor (Hewitt), A. cregoi (Boulenger) and A. rieppeli (Sternfeld). Our molecular results support other lines of evidence (consistent morphological differences and parapatric distributions between the subspecies) in suggesting that each of these subspecies are taxonomically distinct. In light of this, and supported by the genetic distances between these subspecies which exceed those of other recognised Acontias species, we propose elevating A. fitzsimonsi (Broadley) and A. parietalis (Broadley) to specific status. Our results further suggest that the melanistic and typically-coloured forms of each taxon are nested within the same clades, supporting previous contentions that melanistic individuals are not cryptic taxa.

Thick-billed grasswren (Amytornis modestus) songs differ across subspecies and elicit different subspecific behavioural responses

ABSTRACTPasserine song has many functions including mate attraction and territory defence. When songs across populations diverge, this can lead to changes in conspecific recognition and barriers to gene flow, which affect evolutionary processes that could lead to speciation. Two subspecies of thick-billed grasswren (Amytornis modestus) have a parapatric distribution characterised as a narrow region of high genetic admixture where the two subspecies meet. Outside the region of parapatry, the subspecies are genetically and morphologically diverged and weak inter-subspecific gene flow is asymmetric from A. m. indulkanna to A. m. raglessi. We examined the differences between song of A. m. indulkanna and A. m. raglessi and experimentally broadcast each subspecies song to compare territory-holder response in relation to intruder subspecies type. Our aim was to determine if territory owners have a different response to intruders based on the subspecific song type. The song of each subspecies contained unique vocal elements that were absent in the other subspecies. A. m. raglessi responded similarly to con-subspecific and hetero-subspecific intruder song, and A. m. indulkanna responded more often and with greater intensity to hetero- compared to con-subspecific intruder song. The stronger response by A. m. indulkanna towards hetero-subspecific intruders provides a plausible behavioural explanation for the observed patterns of asymmetrical gene flow.

In quest of contact: phylogeography of helmeted terrapins (Pelomedusa galeata, P. subrufa sensu stricto).

Based on rangewide sampling and three mitochondrial and two nuclear markers (together up to 1,850 bp and 1,840 bp, respectively), we examine the phylogeography of two helmeted terrapin species (Pelomedusa galeata and P. subrufa sensu stricto) and infer shifts of climatically suitable spaces since the Last Glacial Maximum using a modeling approach. Whilst P. galeata displays significant phylogeographic structuring across its range and consists of two deeply divergent lineages that could represent distinct species, P. subrufa shows no obvious phylogeographic differentiation. This seems to be related to historically stable or fluctuating ranges. One of the lineages within P. galeata appears to be confined to the westernmost, winter-rainfall region of South Africa and deserves special conservational attention due to the scarcity of surface water. The other lineage is distributed further east and is differentiated in three weakly supported subclades with parapatric distribution; one occurring inland, and two along the south and east coasts, respectively. As far as is known, P. subrufa occurs in South Africa only in the northeast of the country (Limpopo, Mpumalanga) and we report the species for the first time from the Lapalala Wilderness Area in the Waterberg region (Limpopo), approximately 350 km further west than previously recorded. We confirmed the occurrence of P. galeata only 80 km south of Lapalala. Thus, a sympatric occurrence of P. galeata and P. subrufa is possible. Another putative contact zone, for the two lineages within P. galeata, must be located in the Western Cape region, and further contact zones are likely for the eastern subclades within P. galeata. The nuclear loci provided no evidence for gene flow across taxa or genetic clusters within taxa. Future investigations should use denser sampling from putative contact zones and more nuclear markers to re-examine this situation. Despite few phylogeographic studies published for southern African biota, it seems likely that differentiation follows general rules, and that climate and physiographic barriers (e.g., the Great Escarpment) have shaped phylogeographic patterns.

Chloroplast genome analyses and genomic resource development for epilithic sister genera Oresitrophe and Mukdenia (Saxifragaceae), using genome skimming data

BackgroundEpilithic sister genera Oresitrophe and Mukdenia (Saxifragaceae) have an epilithic habitat (rocky slopes) and a parapatric distribution in East Asia, which makes them an ideal model for a more comprehensive understanding of the demographic and divergence history and the influence of climate changes in East Asia. However, the genetic background and resources for these two genera are scarce.ResultsThe complete chloroplast (cp) genomes of two Oresitrophe rupifraga and one Mukdenia rossii individuals were reconstructed and comparative analyses were conducted to examine the evolutionary pattern of chloroplast genomes in Saxifragaceae. The cp genomes ranged from 156,738 bp to 156,960 bp in length and had a typical quadripartite structure with a conserved genome arrangement. Comparative analysis revealed the intron of rpl2 has been lost in Heuchera parviflora, Tiarella polyphylla, M. rossii and O. rupifraga but presents in the reference genome of Penthorum chinense. Seven cp hotspot regions (trnH-psbA, trnR-atpA, atpI-rps2, rps2-rpoC2, petN-psbM, rps4-trnT and rpl33-rps18) were identified between Oresitrophe and Mukdenia, while four hotspots (trnQ-psbK, trnR-atpA, trnS-psbZ and rpl33-rps18) were identified within Oresitrophe. In addition, 24 polymorphic cpSSR loci were found between Oresitrophe and Mukdenia. Most importantly, we successfully developed 126 intergeneric polymorphic gSSR markers between Oresitrophe and Mukdenia, as well as 452 intrageneric ones within Oresitrophe. Twelve randomly selected intergeneric gSSRs have shown that these two genera exhibit a significant genetic structure.ConclusionsIn this study, we conducted genome skimming for Oresitrophe rupifraga and Mukdenia rossii. Using these data, we were able to not only assemble their complete chloroplast genomes, but also develop abundant genetic resources (cp hotspots, cpSSRs, polymorphic gSSRs). The genomic patterns and genetic resources presented here will contribute to further studies on population genetics, phylogeny and conservation biology in Saxifragaceae.

Habitat‐driven diversification, hybridization and cryptic diversity in the Fork‐tailed Drongo (Passeriformes: Dicruridae: Dicrurus adsimilis)

Species complexes of widespread African vertebrates that include taxa distributed across different habitats are poorly understood in terms of their phylogenetic relationships, levels of genetic differentiation and diversification dynamics. The Fork‐tailed Drongo (Dicrurus adsimilis) species complex includes seven Afrotropical taxa with parapatric distributions, each inhabiting a particular bioregion. Various taxonomic hypotheses concerning the species limits of the Fork‐tailed Drongo have been suggested, based largely on mantle and upperpart coloration, but our understanding of diversity and diversification patterns remains incomplete. Especially given our lack of knowledge about how well these characters reflect taxonomy in a morphologically conservative group. Using a thorough sampling across Afrotropical bioregions, we suggest that the number of recognized species within the D. adsimilis superspecies complex has likely been underestimated and that mantle and upperpart coloration reflects local adaptation to different habitat structure, rather than phylogenetic relationships. Our results are consistent with recent phylogeographic studies of sub‐Saharan African vertebrates, indicating that widespread and often morphologically uniform species comprise several paraphyletic lineages, often with one or more of the lineages being closely related to phenotypically distinct forms inhabiting a different, yet geographically close, biome.

Research Article Parapatric speciation found in Limnonectes (Dicroglossidae) species in Thailand

Biodiversity stems from speciation, and species identification allows scientists to measure species biodiversity. However, some closely related species, particularly amphibians that choose to inhabit the same environment, are difficult to identify. Juvenile specimens of Limnonectes gyldenstolpei (Lg) and L. taylori (Lt) were used as models to study the speciation process in populations with a parapatric distribution. Samples of the two species were collected from six provinces in the north and northeast of Thailand. Inter-simple sequence repeat (ISSR) data of five loci showed 96 polymorphic bands and species-specific bands of the primers UBC811 (Lg) and UBC824 (Lt). There was limited genetic variation within the same population, 8% in Lg and 2% in Lt, whereas a high genetic variation was observed between populations from different provinces 90% and 97% in Lg and Lt, respectively. An unweighted pair-group method using arithmetic averages (UPGMA) tree was constructed for each population using Jaccard’s similarity efficient. The tree demonstrated genetic differentiation between the two species. Principal coordinates analysis also supported the UPGMA diagram by showing no clear clusters with close genetic distances. The results of the molecular variance analysis within the population were high, indicating that they were genetically similar, and that microhabitat is an important factor influencing genetic distribution. Overall, the present study proves the hypothesis that the distribution of the two species is in a Parapatric form and that the ISSR technique is inappropriate tool to study the differentiation of a species complex.

Polyploidy and genome size variation in Phlox nana (Polemoniaceae) from the Pecos plains of New Mexico and the Davis Mountains of West Texas

Polyploidy is conspicuous in the genus Phlox, and some species exhibit variation in ploidy levels, or cytotypic variation. Diploid, tetraploid and hexaploid popula-tions of P. nana occur across parts of the species distribution in the southwestern United States and northern Mexico. A recent study highlighted two areas for which ploidy level inferences were challenging: a population on the Pecos Plains of New Mexico (“Caprock”) and the Davis Mountains region of West Texas. Plants in these areas were sampled and chromosome counts and flow cytometry methods were used to assess ploidy levels and genome sizes. Homoploid variation in ge-nome size was unambiguously documented: the genome size of tetraploid plants from the Davis Mountains was significantly larger than that of plants from Caprock. The general condition of larger genome sizes for plants in the Davis Mountains explains previous difficulty in determining ploidy levels within the region. Most plants at the Caprock population appeared to be tetraploid (2n=28), but chromosome counts revealed variants, including some putative pentaploids. Within the Davis Mountains region, both diploid (2n=14) and tetraploid (2n=28) cytotypes were documented, with a parapatric distribution. Overall, this study clarifies patterns of cytotypic diversity in P. nana, highlights an example of infraspecific, homoploid genome size variation, and contributes to a framework for ongoing evolutionary investigation in this study system.

Can Niche Modeling and Geometric Morphometrics Document Competitive Exclusion in a Pair of Subterranean Rodents (Genus Ctenomys) with Tiny Parapatric Distributions?

Species with similar ecological requirements coexisting in the same geographic region are prone to competitively exclude each other. Alternatively, they may coexist if character displacement acts to change the niche requirements of one or both species. We used two methodological approaches (ecological niche modeling [ENM] and geometric morphometrics) to test two hypotheses: given their behavioral, morphological, and ecological similarities, one species competitively excludes the other; and, character displacement enables their coexistence at two sites in which the species are known to occur in sympatry. The results from the ENM-based approach did not provide evidence for competitive exclusion; however, the morphometric analyses documented displacement in size of C. minutus. This result, suggests that C. minutus might exclude C. flamarioni from areas with softer soils and higher food availability. We stress the importance of using multiple methodological approaches when testing prediction of competitive exclusion. However, both methods had limited explanatory power given that the focal species possess truly peculiar distributions, being largely parapatric and restricted to narrow, small geographic areas with a strange distribution and there is a need to search for additional methods. We discuss the idiosyncrasy of the ENM-based approach when applied to organisms with subterranean habits.

Community dynamics of stabilized dune xerophytic shrubs

To conciliate the individualistic and holistic paradigms dominating community ecology, I analysed the main factors driving the distribution of xerophytic shrub communities at different scales. I found that the patchy distribution of xerophytic shrubs in southwestern Portugal mainly responds to both local (i.e., soil organic matter) and regional (i.e., climate) factors, confirming the importance of processes acting at different scales. I propose a conceptual model including the ecological dynamics of these communities supported by the analyses of both kinds of drivers and changes in functional diversity. The ecological dynamics between the communities dominated by Stauracanthus genistoides and Ulex australis throughout their co-occurrence area were significantly consistent, despite the factors driving this successional gradient changing regionally. An integrative approach for linking species diversification and distribution assessed the role of edaphic and climatic requirements in the current parapatric distribution of the three species of the genus Stauracanthus.

Exceptional Chromosomal Evolution and Cryptic Speciation of Blind Mole Rats Nannospalax leucodon (Spalacinae, Rodentia) from South-Eastern Europe.

Mole rats are exclusively subterranean and highly specialized rodents. Their long lifespans, remarkable anti-cancer mechanisms, and various distinctive adaptive features make them a useful research model. Moreover, opposing convergence of morphological traits, they have developed extremely high karyotype variability. Thus, 74 chromosomal forms have been described so far and new ones are being revealed continuously. These evolved during the process of rapid radiation and occur in different biogeographical regions. During research into their reproductive biology we have already provided substantial evidence for species-level separation of these taxa. Here, we review diverse chromosomal forms of the lesser blind mole rat, Mediterranean Nannospalax leucodon, distributed in South-eastern Europe, their karyotype records, biogeography, origin, and phylogeny from our extensive research. In the light of new data from molecular genetic studies, we question some former valuations and propose a cryptospecies rank for seven reproductively isolated chromosomal forms with sympatric and parapatric distribution and clear ecogeographical discrepances in their habitats, as well as new experimental and theoretical methods for understanding the courses of speciation of these unique fossorial mammals.

Molecular taxonomy of the Sympetrum vulgatum (Odonata: Libellulidae) complex in the West Palaearctic

The Sympetrum vulgatum (Linnaeus, 1758) complex is composed of the subspecies S. vulgatum vulgatum, S. vulgatum decoloratum (Selys, 1884) and S. vulgatum ibericum Ocharan, 1985 in the West Palaearctic. These taxa have parapatric distributions and noticeable morphological differences in colour and body size, and their taxonomic status is debated. Here we revise the systematics of this group using molecular taxonomy, including molecular analyses of mitochondrial (cytochrome c oxidase subunit I, COI) and nuclear (internal transcribed spacer, ITS1) DNA taking into account known morphological differences. Each subspecies has a unique and differentiated COI haplotype, although divergences among them are low (0.4% maximum uncorrected p-distance). The subspecies are not differentiated by the nuclear marker ITS1. The genetic results for these taxa contrast with the deep divergence of the sister species S. striolatum (Charpentier, 1840). Given current evidence, we propose to maintain the subspecific status of the S. vulgatum complex and hypothesize their biogeographical history. It is likely that the three subspecies became isolated during one of the latest glacial periods, each in a different refugium: S. vulgatum ibericum possibly occupied the Iberian Peninsula, S. vulgatum vulgatum the Balkan Peninsula or territories further east and S. vulgatum decoloratum Anatolia.