Integration of conflict into integrative taxonomy: fitting hybridization in species delimitation of Mesocarabus (Coleoptera: Carabidae)

In species differentiation, characters may not diverge synchronously, and there are also processes that shuffle character states in lineages descendant from a common ancestor. Species are thus expected to show some degree of incongruence among characters; therefore, taxonomic delimitation can benefit from integrative approaches and objective strategies that account for character conflict. We illustrate the potential of exploiting conflict for species delimitation in a study case of ground beetles of the subgenus Carabus (Mesocarabus), where traditional taxonomy does not accurately delimit species. The molecular phylogenies of four mitochondrial and three nuclear genes, cladistic analysis of the aedeagus, ecological niche divergence and morphometry of pronotal shape in more than 500 specimens of Mesocarabus show that these characters are not fully congruent. For these data, a three‐step operational strategy is proposed for species delimitation by (i) delineating candidate species based on the integration of incongruence among conclusive lines of evidence, (ii) corroborating candidate species with inconclusive lines of evidence and (iii) refining a final species proposal based on an integrated characterization of candidate species based on the evolutionary analysis of incongruence. This procedure provided a general understanding of the reticulate process of hybridization and introgression acting on Mesocarabus and generated the hypothesis of seven Mesocarabus species, including two putative hybrid lineages. Our work emphasizes the importance of incorporating critical analyses of character and phylogenetic conflict to infer both the evolutionary history and species boundaries through an integrative taxonomic approach.     

Phylogenetic relationships and ecological niche conservatism in killifish (Profundulidae) in Mesoamerica

The family Profundulidae is a group of small-sized fish species distributed between southern Mexico and Honduras, where they are frequently the only fish representatives at higher elevations in the basins where they occur. We characterized their ecological niche using different methods and metrics drawn from niche modelling and by re-examining phylogenetic relationships of a recently published molecular phylogeny of this family to gain a better understanding of its biogeographic and evolutionary history. We assessed both lines of evidence from the perspective of niche conservatism to set a foundation for discussing hypotheses about the processes underlying the distribution and evolution of the group. In fish clades where the species composition is not clear, we examined whether niche classification could be informative to discriminate groups geographically and ecologically consistent with any of the different hypotheses of valid species. The characterization of the ecological niche was carried out using the Maxent algorithm under different parameterizations and the projection of the presence on the main components of the most relevant environmental coverage, and the niche comparison was calculated with two indices (D and I), both in environmental space and in that projected geographically. With the molecular data, a species tree was generated using the *BEAST method. The comparison of these data was calculated with an age-overlap correlation test. Based on the molecular phylogeny and on niche overlap analyses, we uncovered strong evidence to support the idea that ecologically similar species are not necessarily sister species. The correlation analysis for genetic distance and niche overlap was not significant (P > 0.05). In clades with taxonomic conflicts, we only identified Profundulus oaxacae as a geographically and ecologically distinct group from P. punctatus. All the evidence considered leads us to propose that Profundulidae do not show evidence of niche conservatism and that there are reasons to consider P. oaxacae as a valid species. Our study suggests that niche divergence is a driving evolutionary force that caused the diversification and speciation processes of the Profundulidae, along with the geological and climatic events that promoted the expansion or contraction of suitable environments.     

Ecological niche modelling and nDNA sequencing support a new, morphologically cryptic beetle species unveiled by DNA barcoding

Background

DNA sequencing techniques used to estimate biodiversity, such as DNA barcoding, may reveal cryptic species. However, disagreements between barcoding and morphological data have already led to controversy. Species delimitation should therefore not be based on mtDNA alone. Here, we explore the use of nDNA and bioclimatic modelling in a new species of aquatic beetle revealed by mtDNA sequence data.

Methodology/Principal Findings

The aquatic beetle fauna of Australia is characterised by high degrees of endemism, including local radiations such as the genus Antiporus. Antiporus femoralis was previously considered to exist in two disjunct, but morphologically indistinguishable populations in south-western and south-eastern Australia. We constructed a phylogeny of Antiporus and detected a deep split between these populations. Diagnostic characters from the highly variable nuclear protein encoding arginine kinase gene confirmed the presence of two isolated populations. We then used ecological niche modelling to examine the climatic niche characteristics of the two populations. All results support the status of the two populations as distinct species. We describe the south-western species as Antiporus occidentalis sp.n.

Conclusion/Significance

In addition to nDNA sequence data and extended use of mitochondrial sequences, ecological niche modelling has great potential for delineating morphologically cryptic species.     

Species delimitation and phylogeography of the Abies chensiensis complex inferred from morphological and molecular data

Species delimitation in the Abies chensiensis complex, consisting of A. chensiensis, A. recurvata, A. ernestii and A. ernestii var. salouenensis, has been the subject of a long‐term dispute, as various taxonomic combinations have been proposed. We combined different lines of evidence, including morphological characters and mitochondrial and plastid DNA sequence data, to assess species delimitation. Plastid DNA sequence variation was highly consistent with the morphological result and separated A. recurvata from the other three taxa, but the mitochondrial DNA genealogy was more strongly related to geographical distribution rather than species delimitation, as proposed in previous studies. On the basis of morphological characters and plastid DNA sequence variation, the current species status of A. recurvata was well supported, and we also accepted A. ernestii and A. ernestii var. salouenensis as varieties of A. chensiensis. Furthermore, the phylogeographical history of A. chensiensis was surveyed by molecular data and ecological niche modelling. On the basis of molecular data, the current phylogeographical pattern of the A. chensiensis complex was probably shaped by recent rapid expansions from multiple refugia in the Hengduan Mountains and habitat contraction after the last glaciation. This hypothesis was supported by the results of ecological niche modelling and previous fossil records. Our findings suggest that these fir taxa might have continued to expand their range after the largest glaciation until the end of the last glaciation, but have contracted since then with the increasing temperature and habitat changes. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 175–188.     

Phylogenetic and ecological structure of Mediterranean caddisfly communities at various spatio‐temporal scales

Aim The evolutionary processes structuring the composition of communities remain unclear due to the complexity of factors active at various spatial and temporal scales. Here, we conducted ecological and evolutionary analyses of communities of caddisflies in the genus Hydropsyche (Insecta: Trichoptera) composed of ecomorphologically differentiated species. Location River ecosystems in the Iberian Peninsula and northern Morocco. Methods Nineteen environmental variables were assessed at 180 local study sites and species presence/absence at these sites was used to determine their ecological niche. The evolutionary framework for all 19 species of Hydropsyche encountered was generated by phylogenetic analysis of the mitochondrial cytochrome c oxidase subunit I gene and three nuclear genes: wingless, elongation factor 1‐alpha and 28S RNA. The phylogenetic tree was used: (1) to assess evolutionary niche conservatism by ecological trait correlation with the tree; and (2) to analyse the phylogenetic relatedness of community member species, at three spatial scales (local stream reaches, drainage basins, biogeographical regions). Results Ecological measurements grouped most species into either headwater, mid‐stream or lowland specialists, and traits presumably relevant to river zonation were found to be phylogenetically conservative. Species assemblages at local stream reaches were mostly mono‐ or dispecific. Species diversity increased at larger spatial scales, by adding species with non‐overlapping ecological niches at the level of river basins and by turnover of anciently differentiated lineages at the level of biogeographical regions. This indicates the effects of competition and niche filtering on community structure locally, and ancient ecological diversification and allopatric speciation, respectively, in building up the species pool at basin and biogeographical scales. Main conclusions The study demonstrates the importance of scale (grain size) in studying what determines community composition. Current ecological factors (i.e. competitive exclusion) in Hydropsyche were evident only when studying narrow local sites, while studies of assemblages at larger spatial scales instead demonstrated the roles of ecological niche differentiation, phylogenetic history of trait diversification and allopatric speciation. Increasing the grain size of investigation reveals different portions of correlated spatial and evolutionary processes.     

The role of pollinators in floral diversification in a clade of generalist flowers

Pollinator‐mediated evolutionary divergence has seldom been explored in generalist clades because it is assumed that pollinators in those clades exert weak and conflicting selection. We investigate whether pollinators shape floral diversification in a pollination generalist plant genus, Erysimum. Species from this genus have flowers that appeal to broad assemblages of pollinators. Nevertheless, we recently reported that it is possible to sort plant species into pollination niches varying in the quantitative composition of pollinators. We test here whether floral characters of Erysimum have evolved as a consequence of shifts among pollination niches. For this, we quantified the evolutionary lability of the floral traits and their phylogenetic association with pollination niches. As with pollination niches, Erysimum floral traits show weak phylogenetic signal. Moreover, floral shape and color are phylogenetically associated with pollination niche. In particular, plants belonging to a pollination niche dominated by long‐tongued large bees have lilac corollas with parallel petals. Further analyses suggest, however, that changes in color preceded changes in pollination niche. Pollinators seem to have driven the evolution of corolla shape, whereas the association between pollination niche and corolla color has probably arisen by lilac‐flowered Erysimum moving toward certain pollination niches for other adaptive reasons.     

Identification of ecophenotypic trends within three European freshwater mussel species (Bivalvia: Unionoida) using traditional and modern morphometric techniques

Most species of freshwater mussels (Unionoida) show a wide variability in shell form and size but an understanding of which factors determine unionoid morphology is poor. We identified ecophenotypic trends in shell and internal characters within three unionoid species from two habitat types (marinas and river) of the River Thames, UK, using traditional and modern morphometric techniques. In marinas, all species grew to larger maximum sizes than in the river, which might be a result of higher temperatures and phytoplankton densities in marinas. Unio pictorum in marinas was more elongated than in the river and Fourier shape analysis revealed a trend from dorsally arched river specimens to straight dorsal and pointed posterior margins in marina individuals. The degree of shell elongation and shape of dorso‐posterior margin were not associated with sediment composition, but were associated with the different hydrological characters of the two habitat types. Relative shell width was a poor indicator of collection site and influenced by allometric growth. Unlike U. pictorum, a difference in shell elongation of marina and river mussels could not be detected in Unio tumidus and Anodonta anatina. However, all three species showed the same trends regarding the shape of the dorso‐posterior shell margin. This shell character may thus have broad ecological significance and could have considerable utility to palaeontologists, taxonomists, and conservation biologists. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 814–825.     

Using ecological niche modelling to evaluate niche stability in deep time

Aim To investigate relative niche stability in species responses to various types of environmental pressure (biotic and abiotic) on geological time‐scales using the fossil record. Location The case study focuses on Late Ordovician articulate brachiopods of the Cincinnati Arch in eastern North America. Methods Species niches were modelled for a suite of fossil brachiopod species based on five environmental variables inferred from sedimentary parameters using GARP and Maxent . Niche stability was assessed by comparison of (1) the degree of overlap of species distribution models developed for a time‐slice and those generated by projecting niche models of the previous time‐slice onto environmental layers of a second time‐slice using GARP and Maxent , (2) Schoener’s D statistic, and (3) the similarity of the contribution of each environmental parameter within Maxent niche models between adjacent time‐slices. Results Late Ordovician brachiopod species conserved their niches with high fidelity during intervals of gradual environmental change but responded to inter‐basinal species invasions through niche evolution. Both native and invasive species exhibited similar levels of niche evolution in the invasion and post‐invasion intervals. Niche evolution was related mostly to decreased variance within the former ecological niche parameters rather than to shifts to new ecospace. Main conclusions Although the species examined exhibited morphological stasis during the study interval, high levels of niche conservatism were observed only during intervals of gradual environmental change. Rapid environmental change, notably inter‐basinal species invasions, resulted in high levels of niche evolution among the focal taxa. Both native and invasive species responded with similar levels of niche evolution during the invasion interval and subsequent environmental reorganization. The assumption of complete niche conservatism frequently employed in ecological niche modelling (ENM) analyses to forecast or hindcast species geographical distributions is more likely to be accurate for climate change studies than for invasive species analyses over geological time‐scales.     

Taxonomy of Mechanitis (F.) (Lepidoptera: Nymphalidae) from the West Colombian Andes: an Integrative Approach

Species identification in the butterfly genus Mechanitis (F.) (Lepidoptera: Nymphalidae) becomes difficult when it is based only on wing color patterns, a common practice in butterfly taxonomy. Difficulties in Mechanitis taxonomy are related to the widespread mimicry and polymorphism among species belonging to this genus. Species recognition and inventories of Mechanitis genus in geographic areas as the Andean region of Colombia are of particular interest and the use of more than one character for taxonomic identification is desirable. In this study, we included morphological, ecological, and mitochondrial DNA data to identify the occurring species in this region. Species of Mechanitis were studied from ecological, morphological, and molecular perspectives considering host plant identification, oviposition behavior, and life cycles under laboratory conditions. Immature morphology, patterns of wing color, and genital structures of adults were also studied. The genetic barcoding region of the cytochrome oxidase I mitochondrial gene was sequenced and used to verify the limits between species previously defined by the other characters and to validate its usefulness for species delimitation in this particular genus. The integrative approach combining independent datasets successfully allowed species identification as compared to the approach based on a single dataset. Three well-differentiated species were found in the studied region, Mechanitis menapis (Hewitson), Mechanitis polymnia (Linnaeus), and Mechanitis lysimnia (Fabricius). New valuable characters that could improve taxonomic identification in this genus are considered.     

Divergence in the shell morphology of the land snail genus Aegista (Pulmonata: Bradybaenidae) under phylogenetic constraints

The role of natural selection in phenotypic evolution is central to evolutionary biology. Phenotypic evolution is affected by various factors other than adaptation, and recent focus has been placed on the effects of phylogenetic constraints and niche conservatism on phenotypic evolution. Here, we investigate the relationship between the shell morphology and habitat use of bradybaenid land snails of the genus Aegista and clarify the causes of the divergence in shell morphology among phylogenetically related species. The results of ancestral state reconstruction showed that arboreal species have evolved independently from ground‐dwelling species at least four times. A significant association was found between shell shape and habitat use, despite the existence of a certain degree of phylogenetic constraint between these traits. A principal component analysis showed that arboreal species tend to have a relatively high‐spired shell with a narrow umbilicus. By contrast, ground‐dwelling species have a low‐spired shell with a wide umbilicus. Although the latitude and elevation of the sampling locations showed no relationship with shell morphology, the geology of the sampling locations affected the shell size of arboreal species. The development of a well‐balanced shell shape is one effective method for reducing the cost of locomotion under the force of gravity in each life habitat, resulting in the divergence in shell morphology and the independent evolution of morphologically similar species among different lineages. The present study suggests that ecological divergence is probably the cause of shell morphology divergence in land snails. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 229–241.     

Niches within a niche: ecological differentiation of subterranean amphipods across Europe's interstitial waters

Species that successfully colonized subterranean environments are subject to two opposing selection processes. Stringent abiotic factors select for convergent adaptations, such as loss of eyes and pigments, while interspecific competition drives between‐species divergence. Subterranean species can resolve opposing selection by adaptation to physically different microhabitats. Yet, species frequently co‐occur in physically homogeneous subterranean habitats, like interstitial. These co‐occurrences in such a narrow ecological context can be explained either by equalizing mechanisms, in which neither of the co‐occurring species has a competitive advantage, or by more complex niche models that include species’ differentiation along a trophic niche axis. We tested these hypotheses using the amphipod genus Niphargus. We analysed Europe‐wide co‐occurrence records of Niphargus species from interstitial habitats, split into six independent large‐scale regions. Firstly, we addressed whether species’ pairwise co‐occurrences are random using a probabilistic model. Secondly, we tested whether species cluster into distinct functional–morphological groups and whether ecologically or phylogenetically distinct species are more likely to co‐occur. We found that 68% of species co‐occurrences were not different from random expectation, indicating that most species had access to most sites within each region. The remaining 32% co‐occurred either significantly more or less often than expected by chance. Cluster analysis of functional morphological characters showed that interstitial species belong to two feeding types, micro‐ and macrofeeders, likely representing two peaks of the interstitial adaptive landscape, and hinting that niche divergence, as a mechanism allowing coexistence, is favoured. Finally, we found that the number of co‐occurrences increases with increasing differentiation of functional morphology, but not phylogenetic differences. We conclude that ecological differentiation may be important in shaping such interstitial communities.     

The use of geostatistics and GIS for evolutionary history studies: the case of the nose‐horned viper (Vipera ammodytes) in the Balkan Peninsula

Geostatistics and geographical information system (GIS) procedures are novel techniques helpful for the identification of environmental correlates sustaining contact zones among subspecies or closely related species. In this paper, we tried to infer evolutionary scenarios for Vipera ammodytes across the European part of its distribution area using geostatistics and ecological niche‐based models, hence trying to solve several biogeographical questions that remained unclear after the application of classical morphological tools and genetic analyses. Eleven morphological traits from 871 vipers were analysed with geostatistics and ecological niche‐based modelling. Interpolation by kriging was used to generate surfaces of morphological variation, which were combined with spatial principal components analysis (SPCA). SPCA maps were used to test putative morphological differentiated groups with discriminant function analysis (DFA). Maximum entropy modelling and seven environmental variables were used to identify factors limiting the distribution of groups and areas for the potential occurrence of such groups. Three patterns of morphological variation were observed: a north‐west/south‐west cline, transition zones with steep clines of variation in a west–east arc, and particular character traits that disturbed the general cline. SPCA identified between three and nine putative population groups, of which three were supported by DFA. Areas of potential occurrence of these groups were coherent with the range of the three subspecies of V. ammodytes currently recognized. The distribution of all subspecies was mostly related to precipitation in the driest month. Areas of probable sympatry between subspecies are generally small and restricted. The main patterns of geographic variation of morphological characters for V. ammodytes were similar to the patterns obtained for Vipera latastei and Vipera monticola; the same environmental factors limit the distribution of differentiated groups of vipers in the Balkans and the Iberian Peninsula. The influence of humidity on the variation of morphological traits in spatially separated viper taxa from the two European peninsulas coincides with their phylogenetic relatedness. Geostatistics and GIS procedures were successful in the identification of environmental correlates sustaining contact zones among V. ammodytes subspecies in the Balkans. The same techniques should be applied for studying other parapatric forms and refugia regions. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 651–666.     

pH optima for Danish forest species compared with Ellenberg reaction values

Species distribution depends on the physiological and ecological niche where a species can exist and regenerate in resource competition with other species (niche limitation). The realized niche is influenced by local biotic processes that influence species behaviour and the shape of the response curves relative to environmental gradients. Processes on larger scales also influence the species niche through source-sink mechanisms (dispersal limitation) and the species richness of an area (pool limitation). Despite the growing evidence of skewed or irregular species response curves along gradients, many ecologists still assume symmetric, unimodal response curves along gradients in ecological interpretation. Ellenberg’s indicator system is probably the most common example. However, the assumption is not ecologically or statistically valid, due to the many different processes affecting the distribution of plant species. Here I present the results of Huisman-Olff-Fresco (HOF) regressions for 209 Danish forest species. HOF modelling is chosen to avoid the classical drawbacks of assuming symmetric, unimodal response patterns. I calculate the optima for all species with unimodal responses to soil pH and compare these with the Ellenberg indicator values for reaction (R), which are often used as a substitute for soil pH measurements. I demonstrate that the assumption of symmetric, unimodal species behaviour is violated in 54% of the cases and that pH optima and R indicator values for species are not always compatible. Ellenberg reaction scale has been used byEwald (Folia Geobot. 38: 357–366, 2003) as an indicator of which species are calcicole, i.e., whether they can grow and reproduce on calcareous soils. Such affinities of species, however, are related to both local niche properties and processes on large scales and cannot be generalized from a single empirical variable such as pH, nor from Ellenberg semi-ordinal indicator scale. I conclude that while the determination of whether species are calcicole or calcifuge requires more research, it is evident that Denmark contains a fairly balanced number of calciphytic and acidophytic species. This is probably due to the nearly equal areas with acidic and alkaline soils in Denmark, which also contribute to the high species richness of more than 500 vascular plant species in Danish forests.     

Geographic distribution and phenetic skull variation in two close species of Graomys (Rodentia, Cricetidae, Sigmodontinae)

The interspecific differentiation of South American rodents of the genus Graomys was assayed at ecological and morphometric levels in two species. At the ecological level, niche modelling was used. At the morphometric level, the hypothesis that the size and shape of the skull vary with the geographic location was tested using geometric morphometrics by assessing the extent and spatial distribution of phenotypic skull variation within and among two species, Graomys griseoflavus and Graomys chacoensis. Our results of niche modelling indicate the spatial differentiation between the two species, with G. chacoensis inhabiting preferably the Chaco ecoregion and G. griseoflavus inhabiting mainly the Monte ecoregion. In multiple linear regressions, approximately 20% of the skull size variation is explained by latitude, altitude, and temperature seasonality. The partial least square analysis reveals strong correlation between shape and environmental variables, mainly with latitude, annual mean temperature, and annual precipitation. Discrimination between G. griseoflavus and G. chacoensis was highly reliable when using geometric morphometric tools. These results permit us to elucidate some evolutionary processes that have occurred in these species.     

Otolith shape lends support to the sensory drive hypothesis in rockfishes

The sensory drive hypothesis proposes that environmental factors affect both signalling dynamics and the evolution of signals and receivers. Sound detection and equilibrium in marine fishes are senses dependent on the sagittae otoliths, whose morphological variability appears intrinsically linked to the environment. The aim of this study was to understand if and which environmental factors could be conditioning the evolution of this sensory structure, therefore lending support to the sensory drive hypothesis. Thus, we analysed the otolith shape of 42 rockfish species (Sebastes spp.) to test the potential associations with the phylogeny, biological (age), ecological (feeding habit and depth distribution) and biogeographical factors. The results showed strong differences in the otolith shapes of some species, noticeably influenced by ecological and biogeographical factors. Moreover, otolith shape was clearly conditioned by phylogeny, but with a strong environmental effect, cautioning about the use of this structure for the systematics of rockfishes or other marine fishes. However, our most relevant finding is that the data supported the sensory drive hypothesis as a force promoting the radiation of the genus Sebastes. This hypothesis holds that adaptive divergence in communication has significant influence relative to other life history traits. It has already been established in Sebastes for visual characters and organs; our results showed that it applies to otolith transformations as well (despite the clear influence of feeding and depth), expanding the scope of the hypothesis to other sensory structures.     

Population demography influences climatic niche evolution: evidence from diploid American Hordeum species (Poaceae)

In this study, we explore the interplay of population demography with the evolution of ecological niches during or after speciation in Hordeum. While large populations maintain a high level of standing genetic diversity, gene flow and recombination buffers against fast alterations in ecological adaptation. Small populations harbour lower allele diversity but can more easily shift to new niches if they initially survive under changed conditions. Thus, large populations should be more conservative regarding niche changes in comparison to small populations. We used environmental niche modelling together with phylogenetic, phylogeographic and population genetic analyses to infer the correlation of population demography with changes in ecological niche dimensions in 12 diploid Hordeum species from the New World, forming four monophyletic groups. Our analyses found both shifts and conservatism in distinct niche dimensions within and among clades. Speciation due to vicariance resulted in three species with no pronounced climate niche differences, while species originating due to long‐distance dispersals or otherwise encountering genetic bottlenecks mostly revealed climate niche shifts. Niche convergence among clades indicates a niche‐filling pattern during the last 2 million years in South American Hordeum. We provide evidence that species, which did not encounter population reductions mainly showed ecoclimatic niche conservatism, while major niche shifts occurred in species which have undergone population bottlenecks. Our data allow the conclusion that population demography influences adaptation and niche shifts or conservatism in South American Hordeum species.     

Inferring evolutionary scenarios with geostatistics and geographical information systems for the viperid snakes Vipera latastei and Vipera monticola

The present study aimed to infer evolutionary scenarios for Vipera latastei and Vipera monticola in the Iberian Peninsula and the Maghreb through the identification of spatial patterns in morphological character variation and biogeographic patterns in morphological variability distribution. Ten morphological traits from 630 vipers were analysed with geostatistic and ecological niche modelling in a geographical information system. Interpolation by Kriging was used to generate surfaces of morphological variation, which were combined with spatial principal components analysis (SPCA). Putative morphological differentiated groups generated by SPCA maps were tested with discriminant function analysis (DFA). Maximum entropy modelling and nine environmental variables were used to identify factors limiting the distribution of groups and areas for their potential occurrence. Groups supported by DFA were: Western Iberia, Eastern Iberia, Rif plus Middle Atlas, Algeria, and High Atlas. Their distribution is influenced by common environmental factors such as precipitation. Areas of probable sympatry between Iberian groups matched the morphological clines observed by geostatistics tools. Geographic variation patterns in V. latastei‐monticola are probably due to vicariant separation of Iberian and African populations during the opening of the Strait of Gibraltar, and population refugia during the Quaternary glaciations with secondary contact. The taxonomic status of northern Morocco and Algerian groups should be further investigated. We conclude that geostatistics and niche‐modelling tools are adequate to infer morphological variability across wide geographic ranges of species. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 790–806.     

How cold‐adapted flightless flies dispersed over the northern hemisphere: phylogeny and biogeography of the snow fly genus Chionea Dalman (Diptera: Limoniidae)

A phylogeny of the 37 known species and subspecies of the micropterous snow fly genus Chionea Dalman is presented using adult morphological characters. The genus contains two major clades: a strictly Palaearctic clade, and a combined Nearctic‐Palaearctic clade with representatives in the Nearctic and Western Palaearctic regions. As there is little congruence between the recovered phylogeny of Chionea and the currently used subgeneric division in Chionea s.s. and Sphaeconophilus Becker, we propose to abandon the use of subgeneric taxa in Chionea. A strictly morphological analysis appears to be insufficient to fully resolve the phylogeny of the genus at the species level, and future molecular work should provide additional evidence for the establishment of relationships among the members of Chionea. The large‐scale historical biogeography of Chionea was analysed using dispersal‐vicariance analysis. The initial distribution area of the genus probably extended in the Eastern Palaearctic, and the Nearctic and the origin of Chionea could be dated in the Late Cretaceous. The various dispersal and vicariance events that led to the major speciation events in the genus are set against major paleogeographic developments. The ancestor of the Western Palaearctic group in the second major clade originated from the Nearctic. The presence of the cold‐adapted Chionea in currently temperate to warm climatic zones in the southern parts of its distribution was analysed using ecological niche modelling. It appears that prolonged periods of climate cooling, as occurred during the Last Glacial Maximum, enabled Chionea to cover large parts of central and southern Europe and reach the southern distribution areas where the genus is present today. A similar biogeographic pattern was less evident in the Nearctic region.