Leaf morphological variation in beech (Fagus sylvatica L.) populations in Greece and its relation to their post‐glacial origin

Diversity in leaf morphological traits was assessed in 38 Greek Fagus sylvatica populations, covering the distribution of the species in the country. The relationship between the post‐glacial origin of these populations and leaf morphology was investigated. The results showed a complex and geographically continuous morphological diversity pattern, influenced mainly by traits expressing leaf size, leaf shape and petiole length. Two simultaneous trends appeared to be responsible for the existing diversity pattern. One was geographical, with leaf types resembling F. sylvatica subsp. sylvatica occurring in the western part of the distribution of beech in Greece and types resembling F. sylvatica subsp. orientalis being dominant in the eastern part. A second trend seemed to be connected with the post‐glacial origin of the populations, as described by previous plastid DNA haplotype studies of the same trees. The genetic background and the possible adaptation of beech populations to different environmental conditions have resulted in a complex morphological pattern, especially in areas in which different post‐glacial lineages appear to meet. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 422–436.     

Effects of the evolution of the Serra do Mar mountains on the shape of the geographically isolated populations of Aegla schmitti Hobbs III, 1979 (Decapoda: Anomura)

The Aeglidae family is a useful model for evaluating the shape variation to present small geographically isolated populations and present a carapace structure that allows precise placement of landmarks. We analysed variations of the size and shape of the carapace of seven populations of A. schmitti. We used 18 bidimensional anatomical landmarks on the carapace of adult males. Size variation between the populations was analysed through a univariate analysis of variance, while the shape variation was analysed through a multivariate analysis of variance using the configurations aligned by the generalized Procrustes analysis. The ordination of the populations was investigated through a canonical variables analysis. Individuals from the populations differed in the carapace size, in this case, we observed the largest individuals in the Iguaçu river basin, followed by Ribeira do Iguape and the Coastal basin. Carapace shape also differed between the populations of A. schmitti, with the exception of the Mato Grande and Piraquara rivers: populations from the Iguaçu River presented a larger and rounder carapace when compared with the slenderer carapace of the Coastal basin, and the Ribeira do Iguape animals presented intermediate shapes. Data from the present study show great congruency with the draining pattern and geological history of the region.     

The geographic structure of morphological variation in eight species of fiddler crabs (Ocypodidae: genus Uca) from the eastern United States and Mexico

Species with larger geographic distributions are more likely to encounter a greater variety of environmental conditions and barriers to gene flow than geographically‐restricted species. Thus, even closely‐related species with similar life‐history strategies might vary in degree and geographic structure of variation if they differ in geographic range size. In the present study, we investigated this using samples collected across the geographic ranges of eight species of fiddler crabs (Crustacea: Uca) from the Atlantic and Gulf coasts of North America. Morphological variation in the carapace was assessed using geometric morphometric analysis of 945 specimens. Although the eight Uca species exhibit different degrees of intraspecific variation, widespread species do not necessarily exhibit more intraspecific or geographic variation in carapace morphology. Instead, species with more intraspecific variation show stronger morphological divergence among populations. This morphological divergence is partly a result of allometric growth coupled with differences in maximum body size among populations. On average, 10% of total within‐species variation is attributable to allometry. Possible drivers of the remaining morphological differences among populations include gene flow mediated by ocean currents and plastic responses to various environmental stimuli, with isolation‐by‐distance playing a less important role. The results obtained indicate that morphological divergence among populations can occur over shorter distances than expected based on dispersal potential. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 248–270.     

Body size variation and caste ratios in geographically distinct populations of the invasive big‐headed ant,Pheidole megacephala (Hymenoptera: Formicidae)

Body size is an important life history trait that can evolve rapidly as a result of how species interact with each other and their environment. Invasive species often encounter vastly different ecological conditions throughout their introduced range that can influence relative investment in growth, reproduction and defence among populations. In this study, we quantified variation in worker size, morphology and proportion of majors among five populations of a worldwide invasive species, the big‐headed ant, Pheidole megacephala (Fabricius). The sampled populations differed in ant community composition, allowing us to examine if P. megacephala invests differently in the size and number of majors based on the local ant fauna. We also used genetic data to determine if these populations of P. megacephala represented cryptic species or if morphological differences could be attributed to change following introduction. We found significant variation in worker mass among the populations. Both major and minor workers were largest in Australia, where the ant fauna was most diverse, and minor workers were smallest in Hawaii and Mauritius, where P. megacephala interacted with few to no other ants. We also found differences in major and minor worker morphology among populations. Majors from Mauritius had significantly larger heads (width and length) relative to whole body size than those from Hawaii and Florida. Minors had longer heads and hind tibias in South Africa compared with populations from Australia, Hawaii and Florida. The proportion of majors did not differ among populations, suggesting that these populations may not be subject to trade‐offs in investment in major size versus number. Our molecular data place all samples within the same clade, supporting that these morphologically different populations represent the same species. These results suggest that the variation in shape and morphology of major and minor workers may therefore be the result of rapid adaptation or plastic responses to local conditions. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 423–438.     

Genetic and morphological analyses reveal a complex biogeographic pattern in the endemic barbel populations of the southern Italian peninsula

The Italian peninsula is a biodiversity hotspot, with its freshwater fish fauna characterized by high levels of local endemism. Two endemic fluvio‐lacustrine fishes of the genus Barbus (barbel, family Cyprinidae) have allopatric distributions in the Tyrrhenian and Adriatic basins of Italy. Barbus plebejus inhabits the mid‐ to northern Adriatic basins, while B. tyberinus is widespread in all central‐northern basins draining into the Tyrrhenian Sea. For basins in Southern Italy draining into the southern parts of these seas, there remains a knowledge gap on their barbel populations due to no previous genetic and morphological studies, despite their apparent biogeographic isolation. Correspondingly, this study quantified the presence and distribution of barbels in the Adriatic and Tyrrhenian basins of Southern Italy through genetic and morphological analyses of 197 fish sampled across eight populations. Testing of how local isolation has influenced the evolution and persistence of these populations was completed by examining sequence variation at two mitochondrial loci (cytochrome b and D‐loop) and performing geometric morphometric analyses of body shape, plus measuring 11 morphometric and meristic characters. Phylogenetic and morphological analyses revealed the presence of two genetically distinct lineages that differed significantly from adjacent B. tyberinus and B. plebejus populations. These two new taxa, here described as SI1 and SI2 Barbus lineages, are highly structured and reflect a complex mosaic biogeographic pattern that is strongly associated with the underlying hydrographical scenarios of the basins. The geographic isolation of these basins thus has high evolutionary importance that has to be considered for maintaining endemism.     

Hybridization between genetically and morphologically divergent forms of Rhagada (Gastropoda: Camaenidae) snails at a zone of secondary contact

Congeneric sympatry is rare in Australian camaenid land snails, and the reasons are poorly understood. As the first example of contact between species of the Western Australian genus Rhagada, we examined the parapatric zone between the coastally distributed Rhagada convicta and an undescribed inland species, which differ in size, shape, and banding of their shells and in their reproductive systems. Phylogenetic analysis of sequences of the mitochondrial 16S RNA gene indicated secondary contact between two distinct clades, with an average sequence divergence of 6.5%. Despite these substantial differences, the two forms hybridize in the narrow contact zone, resulting in intermediate phenotypes for shells and reproductive anatomy, and incongruence of the mitochondrial DNA (mtDNA) lineage and morphology. Hybridization appears to be asymmetric, however, as all morphological intermediates possessed the R. convicta mtDNA. Interbreeding between these deeply divergent forms challenges the use of reproductive structures as indicators of reproductive isolation in snail taxonomy. This is the first contact zone detected between mainland species of Rhagada and indicates that the widespread pattern of geographical replacement is not simply a result of allopatric divergence without subsequent contact. Instead, the perspective for understanding the radiation and geographical distributions must include interactions between the species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 348–362.     

Stylar polymorphism on the edge: unusual flower traits in Moroccan Narcissus broussonetii (Amaryllidaceae)

Heterostyly and related polymorphisms (e.g. stigma‐height dimorphism) have been used as model systems for studying the origin and maintenance of plant population variability. Stigma‐height dimorphism frequently occurs in Narcissus and is associated with a particular flower shape. In the present study, we describe a new, peculiar case of stigma‐height dimorphism in Narcissus broussonetii, a species on the margin of the geographical distribution of the genus. We determined the stylar condition of N. broussonetii and its variation across populations, analyzed perianth morphology and its relationship with stylar variation, and compared this species with other stylar dimorphic species of the genus. We also studied the incompatibility system and pollination ecology of the species. Narcissus broussonetii is a style‐dimorphic species, as suggested in early studies that were subsequently neglected, and displays unusual flower morphology, with a long floral tube and a virtual absence of a corona. The species shows a late‐ (ovarian) acting incompatibility system and crosses within and between morphs are fertile. We observed short‐tongued diurnal and long‐tongued nocturnal pollinators. Our findings confirm that the presence of the observed dimorphism across populations is most probably the result of the joint action of a nonheteromorphic incompatibility system, extremely long and narrow floral tubes, and a combined role of short‐ and long‐tongued pollinators. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 644–656.     

A new species of Dianthus (Caryophyllaceae) from Mount Erciyes,central Anatolia,Turkey

Dianthus aytachii C.Vural from Mount Erciyes, central Anatolia (Turkey) is described and illustrated. It is considered to be endemic to Mount Erciyes. The morphological differences from the closely related species Dianthus zederbaueri Vierh. are discussed. The World Conservation Union (IUCN) threat category and observations on the ecology of the populations are noted. The pollen and seed morphology of D. aytachii and D. zederbaueri were examined by light microscopy and scanning electron microscopy. The geographical distribution of the new species is mapped. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 55–61.     

Clinal variation or validation of a subspecies? A case study of the Graptemys nigrinoda complex (Testudines: Emydidae)

Widely distributed species often display intraspecific morphological variation due to the abiotic and biotic gradients experienced across their ranges. Historically, in many vertebrate taxa, such as birds and reptiles, these morphological differences within a species were used to delimit subspecies. Graptemys nigrinoda is an aquatic turtle species endemic to the Mobile Bay Basin. Colour pattern and morphological variability were used to describe a subspecies (G. n. delticola) from the lower reaches of the system, although it and the nominate subspecies also reportedly intergrade over a large portion of the range. Other researchers have suggested that these morphological differences merely reflect clinal variation. Our molecular data (mtDNA) did not support the existence of the subspecies, as the haplotypes were differentiated by only a few base pairs and one haplotype was shared between the putative subspecies. While there were significant morphological and pattern differences among putative specimens of G. n. nigrinoda, G. n. delticola and G. n. nigrinoda × delticola, these differences probably represent clinal variation as they were also related to environmental variables [i.e. cumulative drainage area and drainage (categorical)]. Specimens occupying slow‐current, high‐turbidity river reaches (e.g. the Tensaw River) exhibited greater relative carapace heights and more dark pigmentation, while specimens occupying fast‐current, clearer rivers (e.g. the upper Alabama, Cahaba and Tallapoosa rivers) exhibited lower carapace heights and more yellow pigmentation. Given the absence of clear molecular and morphological differences that are related to drainage characteristics, we suggest that there is not sufficient evidence for the recognition of G. n. delticola as a distinct subspecies. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 810–822.     

Morphological divergence of North‐European nine‐spined sticklebacks (Pungitius pungitius): signatures of parallel evolution

Parallel evolution is characterised by repeated, independent occurrences of similar phenotypes in a given habitat type, in different parts of the species distribution area. We studied body shape and body armour divergence between five marine, four lake, and ten pond populations of nine‐spined sticklebacks [Pungitius pungitius (Linnaeus, 1758)] in Fennoscandia. We hypothesized that marine and lake populations (large water bodies, diverse fish fauna) would be similar, whereas sticklebacks in isolated ponds (small water bodies, simple fish fauna) would be divergent. We found that pond fish had deeper bodies, shorter caudal peduncles, and less body armour (viz. shorter/absent pelvic spines, reduced/absent pelvic girdle, and reduced number of lateral plates) than marine fish. Lake fish were intermediate, but more similar to marine than to pond fish. Results of our common garden experiment concurred with these patterns, suggesting a genetic basis for the observed divergence. We also found large variation among populations within habitat types, indicating that environmental variables other than those related to gross habitat characteristics might also influence nine‐spined stickleback morphology. Apart from suggesting parallel evolution of morphological characteristics of nine‐spined sticklebacks in different habitats, the results also show a number of similarities to the evolution of three‐spined stickleback (Gasterosteus aculeatus Linnaeus, 1758) morphology. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 403–416.     

Geographical differentiation of Aphanius dispar (Teleostei: Cyprinodontidae) from Southern Iran

The Arabian cyprinodontid Aphanius dispar (Rüppell, 1829) is known to show considerable morphological variation. It has remained unknown, however, whether this variation is a result of environmental differences or allopatric divergence owing to geographical isolation. In this study, 11 populations of A. dispar from three geographically separated basins were analysed, that is, the Makran Basin (I, one river system), the Hormuzgan Basin (II, five rivers and three hot springs) and the Helleh Basin (III, two hot springs) in southern Iran. Statistical analyses do not indicate significant differences between the fishes from river and hot spring habitats (T‐test, p < 0.05), which is also supported by the Canonical Discriminant Analysis (CDA). Nevertheless, morphometric and meristic characters of the fishes, as well as otolith morphology and morphometry, demonstrate that six phenotypic characters discriminate the A. dispar populations of the three basins, that is, (1) predorsal distance (Prdd.SL), (2) head length (HL.SL), (3) pelvic fin length (Lplf.SL), (4) number of pelvic fin rays, as well as relative length of both the (5) medial part and (6) rostrum of the otolith. In addition, these characters display a consistent pattern of variation, thus providing support for the assumption that the phenotypically different A. dispar populations are a result of geographical isolation and not related to environmental differences. It is likely that the geological history of the drainage systems caused isolation event(s) that may date back to the Pleistocene (1.8 million years before present). The high phenotypic differences might suggest that the A. dispar populations from the three studied basins represent separate subspecies or even species.     

Past climatic fluctuations are associated with morphological differentiation in the cloud forest endemic tree <Emphasis Type="Italic">Ocotea psychotrioides</Emphasis> (Lauraceae)

Pleistocene glacial periods have had a major influence on the geographical patterns of genetic structure of species in tropical montane regions. However, their effect on morphological differentiation among populations of cloud forest plants remains virtually unexplored. Here, we address this question by testing whether geographical patterns of morphological variation in Ocotea psychotrioides can be explained by the intensity of climate change occurring during 130,000 years. For this, we measured vegetative and reproductive traits for 96 individuals from 36 localities registered across the species’ distribution range. Species distribution models and multivariate statistics were used to investigate geographical patterns of morphological variation and test their association with current and past climatic conditions. Leaf size and pubescence in O. psychotrioides showed a latitudinal pattern of clinal variation that does not fit the geographical gradient of increasing leaf size towards lower latitudes observed globally among plants. Instead, the observed clinal variation conforms to a pattern of increasing leaf size towards higher latitudes. However, our analyses showed weak to non-significant association between morphology and current climate. Interestingly, our analyses showed that predicted shifts in the distribution range of O. psychotrioides during the last 130,000 years were accompanied by significant changes in climatic conditions, particularly temperature seasonality and precipitation. Accordingly, climatic instability showed a better fit to the observed patterns of leaf size and pubescence variation than current climate conditions. These results suggest that climatic instability during the Pleistocene glacial periods might play a key role in promoting morphological differentiation among populations of cloud forest plants.     

Geographic pattern of cranial differentiation in the Asian Midday Jird Meriones meridianus (Rodentia: Muridae: Gerbillinae) and its taxonomic implications

The existence of cryptic species in the midday jird (Meriones meridianus) has been suggested in literature, although based on little empirical data to support this hypothesis. In this study, a two‐dimensional landmark‐based geometric morphometric approach was used to investigate whether patterns in intraspecific variation in skull shape and size exist, using 110 skull specimens from more than 20 different localities along the distribution range of M. meridianus. This is the first study of morphological differences on such a big sample size and geographical range, and it tries to find whether skull shape variation in this species is best described as being clinal or rather reflecting cryptic diversity. The latter seems to be the case, as a dimorphic skull phenotype was found, reflecting a geographic disparity between the Middle East and the Far East specimens both in shape and in size. Distinct cranial differences were found in the overall cranial size and, also at the level of the inflation of the bulla, the elongation of the nasal, the length of the teeth row and the incisive foramen, as well as the distance in between the latter two. It thus seems that M. meridianus from Middle East is morphologically distinct from that of the Far East. Furthermore, our results also demonstrate that clinal variation could explain variation within Middle East populations, whereas a more heterogenous pattern is found for those of the Far East. The hypothesis that the observed phenotypic variation may reflect cryptic species is discussed, with the recommendation for a thorough taxonomical revision of the genus in the region.     

Morphometric analysis of floral variation in the Pyrola picta species complex (Ericaceae): interpretation and implications for ecological and phylogenetic differentiation

The Pyrola picta species complex of western North America comprises four species (P. picta, P. dentata, P. aphylla and P. crypta) that grow sympatrically in some parts of their collective ranges, have remarkably similar flowers and share pollinators. These species do not exhibit the genetic signatures typical of random or heterospecific mating, but instead show genetic divergence patterns indicating that they maintain surprising levels of reproductive isolation. To better understand how species boundaries are maintained, the current study uses statistical ordination analyses to determine whether species isolation across shared geographical ranges might be achieved through subtle differences in floral characters among species. The possible contribution of differences in flowering phenology (e.g. temporal reproductive isolation) to reproductive isolation was also evaluated for the small subset of populations in which two or more species occur in direct sympatry. Among species in the P. picta complex, there are both phylogenetic and geographical trends in some floral characteristics, whereas other characters do not covary with either geography or species identity. In several sympatric populations, differences in flowering phenology among species suggest that timing plays a major role in non‐random (i.e. mainly conspecific) mating. The conclusions of this study are that reproductive isolation in the P. picta species complex is reinforced by differences in the timing of floral maturation and the morphologies of androecium and floral display characters. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 00 , 000–000.     

Evolution of shape in oligocene and mioceneNotocarinovalva (Ostracoda, Crustacea): A multivariate statistical study

Largely due to L. F. Bookstein, geometric morphometrics has been developed as an amalgamation of techniques drawn from mathematical statistics, non-Euclidean geometry and computer graphics, applied to labelled points (landmarks) and the biological images upon which they are registered. A tool of fundamental importance is the method of interpolation known as the thin-plate spline. Bookstein's sample-oriented procedure of relative warps, applied to data composed of coordinate pairs observed on eight landmarks on three samples of two species of fossil marine ostracods (bivalved microcrustacean),Notocarinovalva airella andN. yulecartensis, separated in time, is used to obtain weight matrices, which, when appropriately partitioned, constitute the familiar data matrices of multivariate statistical analysis. Standard multivariate statistical analysis of samples may be carried out in the tangent space to shape space at the Procrustes average shape. Linear discriminant function scores were used for assessing, approximately, the evolutionary relevance of shape change and change in size (based on standard distance measures) in the species from the upper and lower Oligocene and lower middle Miocene of Victoria, Australia. The findings indicate that a small, though consistent, change in non-uniform shape of the carapace has taken place. The analysis indicates that the evolution in shape of the carapace could have been caused by random genetic drift in moderately large populations, tempered by weak selection.     

Hidden species diversity of Australian burrowing snakes (Ramphotyphlops)

The worm‐like snakes (Scolecophidia; approximately 400 nominal extant species) have a conservative morphology and are among the most poorly‐known terrestrial vertebrates. Although molecular evidence has helped determine their higher‐level relationships, such data have rarely been used to discriminate among species. We generated a molecular data set for the continental Australian blindsnakes (genus Ramphotyphlops) to determine the concordance of molecular and morphological information in the taxonomic recognition of species. Our dataset included 741 specimens morphologically attributed to 27 nominal Ramphotyphlops species. We proposed species hypotheses (SHs) after analysis of sequences from a variable mitochondrial gene (cytochrome b) and examined these SHs with additional evidence from a nuclear gene (prolactin receptor) and geographical data. Although the nuclear marker was not as fast‐evolving and discriminating as the mitochondrial marker, there was congruence among the mitochondrial, nuclear, and geographical data, suggesting that the actual number of species is at least two times the current number of recognized, nominal species. Several biogeographical barriers and complex phytogeographical and geological patterns appeared to be involved in the division of some burrowing snake populations and, by consequence, in their diversification and speciation through isolation. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 427–441.     

Morphological and cytotype variation of wild kiwifruit (Actinidia chinensis complex) along an altitudinal and longitudinal gradient in central‐west China

The Actinidia chinensis complex, a group of commercially important fruits (kiwifruit), is a complex of functionally dioecious lianas of variable ploidy. To understand the cytogeography better and to facilitate breeding in this complex, we examined the ploidy and morphological variations in 16 natural populations of A. chinensis var. chinensis and A. chinensis var. deliciosa across an ecogeographical gradient. Four ploidy levels were found, var. chinensis consisting of diploids and tetraploids and var. deliciosa consisting of tetraploids, pentaploids and hexaploids. Hexaploids were centred in the western Yun‐Gui plateau, tetraploids coexisted with hexaploids or diploids in the middle Yun‐Gui plateau and the Wuling‐Xuefeng mountains, and diploids occurred in the eastern Wuling‐Xuefeng mountains and the Hunan foothills. These findings indicate a gradual, clinal transition from hexaploid to diploid across the elevational and longitudinal gradient. The clear geographical segregation of diploids and hexaploids may have arisen from their differential ecological adaptation in response to altitude and climate, whereas the coexistence of cytotypes (2x–4x, 4x–6x and 4x–5x–6x) might be a result of reproductive barriers, with a particular contribution from the postzygotic reproductive isolation between ploidy races. The geographical pattern and morphological variation of cytotypes suggest a hybrid zone between the varieties in the Wuling‐Xuefeng mountains. The differences in cytotypes which have arisen as a result of ecological adaptation, distribution and morphological characteristics will provide important baseline data for the selection of germplasm and the breeding of kiwifruit. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 72–83.     

Ring Clinal Variation in Morphology of the Green Odorous Frog(Odorrana margaretae)

The green odorous f rog(Odorrana margaretae) has an interesting ring-shaped divergence pattern around the Sichuan Basin and documenting its morphological variations is essential in understanding its evolutionary history. Using curvilinear models,we detected significant geographical clinal variations in morphological traits, particularly sizes, of female O. margaretae. Males had significantly smaller sizes than females, and also had smaller variation ranges than females. One major trend of morphological variations was clinal: populations f rom the west tended to have a larger size with wider head and longer posterior limbs than populations from the east.Species history, with an early extended isolation and two subsequent secondary contacts, may explain most of the geographical clinal variations of O. margaretae.Bioclimatic factors may also contribute in explaining the variance of morphology.