Morphological variation of the Oncocyclus irises (Iris: Iridaceae) in the southern Levant

Morphological traits of Iris section Oncocyclus (Siems.) Baker in the southern Levant (Israel, Jordan, The Palestinian Authority and Sinai/Egypt) were analysed in order to clarify taxonomic relationships among taxa and the validity of diagnostic characters. Floral and vegetative characters were measured in 42 populations belonging to nine species during the peak of the flowering season in 1998–2000. Pearson's Coefficient of Racial Likelihood (CRL) was used to calculate morphological distances between populations. Twelve of the measured populations, distributed along the north-south aridity gradient in Israel, were further explored for morphological changes along the gradient. Cluster analysis revealed two major clusters: the first includes most of the dark-coloured Iris populations, with populations of I. petrana Dinsmore and I. mariae W. Barbey forming a subcluster; the second consists of all the light-coloured populations but also some dark-coloured populations. Pearson's CRL and geographical distance were significantly correlated among the dark-coloured populations. Along the geographical gradient, flower, stem and leaf size traits decrease towards the south, probably as an adaptation to aridity. This suggests that natural selection promoted the differences between populations. Almost no discrete phenotypic groups exist within the Oncocyclus species of the southern Levant except for variation in the floral colours. Most of the suggested diagnostic characters proved unreliable in that they varied continuously across populations. The taxonomical difficulties encountered in this study reflect the special evolutionary state of the Oncocyclus irises as a group in the course of speciation.  © 2002 The Linnean Society of London. Botanical Journal of the Linnean Society , 2002, 139 , 369–382.     

Geographical variation in floral traits of the tree tobacco in relation to its hummingbird pollinator fauna

Nicotiana glauca , a hummingbird pollinated plant, exhibits geographical variation in several floral traits. We examined whether geographical differentiation occurred for different flower characters and if this differentiation could be explained, at least in part, by the existence or abundance of different hummingbird species in the respective pollinator assemblages. The comparison between five populations showed significant variation in six floral traits and two female fitness measures. The traits that better discriminated between populations were corolla length and corolla width. There were metric correlations between corolla length and style length in all populations studied and, in four of the five populations, both corolla length and width were also correlated. Among plants in each population, seed weight was correlated positively and significantly with style exertion, suggesting that fruit quality is dependent on the degree of cross pollination. Assemblages of hummingbirds differed between populations in species composition, visitation frequencies, and bill length. Linear regression involving bill length of the more frequent hummingbird pollinators and corolla length yielded positive and significant relationships. Thus, there appears to be an adjustment between pollinators and flowers traits that have high incidence in the among population variation.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 657–667.     

Character divergences and convergences in canopy-dwelling Loranthaceae

The Loranthaceae is the largest plant family with aerial branch parasites termed mistletoes. Three genera of Loranthaceae are terrestrial root parasites and the remaining 72 genera are aerial parasites. Several characters, including habit, haustorial type, germination pattern, pollen morphology, chromosome number, inflorescence morphology and flower merosity, fusion, symmetry and size, are considered to reflect evolutionary relationships within the family. Convergence is a common evolutionary pattern and can confound interpretations of evolution. We investigated character evolution by mapping character states onto a phylogenetic tree based on the nuclear ITS and chloroplast trnL–trnF regions. Convergences in form were found in several characters, including habit, haustorial type, flower symmetry and merosity. These convergences typically correspond to ecological parameters such as pollination syndrome or stresses associated with the canopy habit. Other characters such as chromosome number and germination pattern illustrate divergent evolution among clades.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 101–113.     

Origin of the disjunct distribution of flower colour polymorphism within Limonium wrightii (Plumbaginaceae) in the Ryukyu Archipelago

The sea lavender, Limonium wrightii , has six morphs of flower colour variation. The geographical distribution of flower colour morphs is disjunct; the distribution of the pink flower morph is divided into two subregions, and that of the yellow flower morph intervenes between them. The present study aimed to examine the origin of this apparent distribution pattern of flower colour in L. wrightii . Two main hypotheses (i.e. past dispersal events and phenotypic changes by natural selection and/or stochastic processes) have been proposed to account for the origin of leapfrog distribution patterns. To determine which hypothesis was applicable, we conducted a molecular phylogenetic analysis using sequence variation in chloroplast DNA (three regions of intergenic spacers, trnG - trnfM , trnV - trnM , and psbA-trnH ). We sequenced 58 accessions of L. wrightii frin 28 islands in the Ryukyu Archipelago and the Izu-Ogasawara Islands, located south of the Japanese mainland, and 12 accessions of four congeneric species. Within L. wrightii , we obtained four lineages of ten haplotypes. These lineages and haplotypes did not correlate with the different flower colours. These results indicate that the formation processes of populations are complex. The haplotypes of the pink flower morph did not show a sister relationship between the two disjunct subregions, indicating that the disjunct populations of the pink flower morphs are unlikely to share the pink flower colour as a result of common ancestry. We conclude that the observed leapfrog distribution pattern is caused by natural selection and/or stochastic processes.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 709–717.     

Wing shape variation in the medium ground finch (Geospiza fortis): an ecomorphological approach

Wing design in birds is subject to a suite of interacting selective pressures. As different performance traits are favoured in different ecological settings, a tight link is generally expected between variation in wing morphology and variation in ecological parameters. In the present study, we document aspects of variation in wing morphology in the medium ground finch ( Geospiza fortis ) on Isla Santa Cruz in the Galápagos. We compare variation in body size, simple morphometric traits (body mass, last primary length, wing length, wing chord, and wing area) and functional traits (wing loading, aspect ratio and wing pointedness) across years, among populations, and between sexes. Functional traits are found to covary across years with differences in climatic conditions, and to covary among populations with differences in habitat structure. In dry years and arid locations, wing aspect ratios are highest and wings are more pointed, consistent with a need for a low cost of transport. In wet years and cluttered habitats, wing loading is lowest and wings are more rounded, suggesting enhanced capabilities for manoeuvrability. Sexes differ in wing loading, with males having lower wing loadings than females. Superior manoeverability might be favoured in males for efficient territory maintenance. Lastly, in contrast to functional traits, we found little consistent inter-annual or inter-site variation in simple morphometric traits.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 129–138.     

Differences in environmental predictability underlie divergent competitive abilities in three congeneric hydroids

Species in which individuals experience predictable and uniform environments should be most finely adapted to their environment. Many hydrozoan species in the genus Hydractinia simultaneously occupy similar microhabitats (gastropod shells inhabited by hermit crabs) but experience considerable differences in their immediate environment (size and species of shells and hosts). In the present study, hydroid species experience differences in environmental predictability and traits that mediate competitive ability (growth form and growth rate). The inferred competitive ability was directly proportional to the extent to which the gastropod environment promotes interactions between small, juvenile colonies, which always end in competitive elimination. Extensive intraspecific variation in competitive ability was explained primarily by crab host species or site. Dense host populations impose more severe disturbance regimes that favour competitively inferior, but disturbance-resistant, phenotypes. Interplay between different types of variation (gastropods and hermit crabs) provides a possible mechanism for the maintenance of intraspecific growth form variation.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 322–338.     

Labile ecotypes accompany rapid cladogenesis in an adaptive radiation of Mandarina (Bradybaenidae) land snails

The endemic land snail genus Mandarina of the oceanic Bonin Islands shows exceptionally diverse morphological and ecological traits. Previous studies have already provided evidence that speciation on different islands of the three main archipelagos was such that similar ecotypes evolved independently in different lineages and islands. Here we present data to show that the same species can have different ecotypes. As most of the characters involved are inherited, then variation between ecotypes must represent genetic differences between populations. We then show that the radiation on the Bonin Islands is derived from a single colonization event, and use a mitochondrial phylogeny to provide evidence for a burst of cladogenesis soon after colonization. As divergent selection has previously been implicated in causing differences between Mandarina species, and theory predicts that most of the speciation should have taken place early in their history, then the study adds to the evidence for an adaptive radiation by ecological speciation in Mandarina . However, while the diversity of ecotypes present at each site is dependent on the regime of natural selection and competition, geography still must have an important role.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 269–282.     

The evolution of locomotor morphology, performance, and anti-predator behaviour among populations of Leiocephalus lizards from the Dominican Republic

Most ecomorphological studies use a comparative approach to examine adaptation by studying variation among species. A question of considerable interest is whether ecomorphological patterns observed among species also exist at the population level. We studied variation in morphology, performance, and behaviour in four populations of Leiocephalus personatus and two populations of Leiocephalus barahonensis in the Dominican Republic. We combined these data with measurements of predation intensity and habitat structure to test for convergence at the population level. We predicted that predation intensity would be higher in open habitats and that lizards in these habitats would have traits conferring higher predator evasion capacity (increased wariness, faster sprint speeds, and longer limbs). Principal components analysis suggests that sites tend to differ with respect to the abundance and spacing of low-lying vegetation (i.e. percentage of shrub cover and distance to nearest vegetation), but we did not detect any striking differences among sites in tail-break frequencies or attacks on clay lizard models. Consistent with predictions we find that in open habitats, lizards tend to have longer limbs, faster sprint speeds (relative to body size), and longer approach distances. These patterns corroborate findings in other ground-dwelling lizard species and indicate that they have evolved at least twice among populations of Leiocephalus lizards. The results of this study also suggest that these traits have evolved rapidly despite recent or ongoing gene flow.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 445–456.     

Ecological opportunity and levels of morphological variance within freshwater stickleback populations

The 'ecological opportunity' hypothesis predicts that when interspecific competition or predation is reduced, populations will exhibit increases in phenotypic variance as a result of colonization and adaptation to vacant or underutilized ecological niches (i.e. character release). We assessed this hypothesis by examining morphological diversity within stickleback populations in 40 undisturbed lakes from six islands off the mid-coast of British Columbia, Canada. Because larger lakes with well-developed littoral and limnetic zones will have greater trophic niche diversity than smaller lakes with only littoral zones, we predicted a positive association between lake size and variation in trophic morphology. Conversely, reduced vertebrate predation in small bog lakes allows increased variance in defensive structures without costs to fitness. Consistent with both predictions, we observed that phenotypic variance in two traits that are involved in feeding (gape width and pectoral fin length) increased with lake size while variability in defence structures (lateral plate number and dorsal spine length) was inversely related to lake size. Moreover, increased variance in defence morphology was accentuated in populations with severe armour reduction (spine loss, decreased plate overlap), another strong indicator of reduced vertebrate predation. In the majority of cases, these patterns were repeatable among islands, independent from the geographical distance between lakes, and arose from a combination of high variance within each of the sexes and increases in sexual dimorphism. These findings suggest that character release can be trait-specific and reflect the combined effects of competition, predation and habitat heterogeneity.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 86 , 297–308.     

Historical DNA from museum type specimens clarifies diversity of Asian leaf turtles (Cyclemys)

Species boundaries in Asian leaf turtles of the genus Cyclemys are difficult to define on the basis of morphology, primarily because many populations exhibit considerable ontogenetic variation in shell and head coloration. Two recent molecular phylogenetic hypotheses of Cyclemys species relationships, based largely on market and pet-trade samples of uncertain provenance, were highly incongruent. We used historical DNA methods to sequence fragments of the mitochondrial cytochrome  b gene from eight type specimens of Cyclemys (including one collected by Alfred Russel Wallace), and phylogenetically placed these type sequences into the context of published cytochrome  b variation. Our phylogenetic hypothesis supports the recognition of four named species ( Cyclemys atripons , Cyclemys dentata , Cyclemys oldhamii , and C. pulchristriata ), as well as a fifth species of unknown geographical provenance obtained from the Hong Kong pet trade. The type sequences show that previous molecular phylogenetic studies were hampered by misidentifications, supporting the notion that Cyclemys of unknown provenance are not reliably identified to species solely on the basis of morphology.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 131–141.     

The relationship between limb morphology, kinematics, and force during running: the evolution of locomotor dynamics in lizards

Terrestrial locomotion occurs via the hierarchical links between morphology, kinematics, force, and center-of-mass mechanics. In a phylogenetically broad sample of seven lizard species, we show that morphological variation drives kinematic variation, which, in turn, drives force variation. Species with short limbs use a short stride–high frequency strategy when running at steady-speed and to change speeds. This link between morphology and kinematics results in relatively small vertical forces during the support phase of the stride cycle. Conversely, species with long limbs use a long stride–low frequency strategy, resulting in large vertical forces during the support phase. In view of these findings, we suggest that limb length may predict locomotor energetics in lizards because energetics are largely determined by vertical forces and stride frequency. Additionally, we propose an energetic trade-off with both long- and short-limbed species paying the most energy to move, whereas intermediate-limbed species move using less energy. Finally, when these traits are mapped onto a lizard phylogeny, we show that locomotor functional morphology exhibits both deep phylogenetic effects and contemporary patterns of evolutionary convergence. Overall, the present study provides a foundation for testing hypotheses regarding the integration and evolution of functional traits in lizards and animals in general.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 634–651.     

Population divergence in the amphicarpic species Amphicarpaea edgeworthii Benth. (Fabaceae): microsatellite markers and leaf morphology

Comparative analyses of the genetic differentiation in microsatellite markers ( F _ST) and leaf morphology characters ( Q _ST) of Amphicarpaea edgeworthii Benth. were conducted to gain insight into the roles of random processes and natural selection in the population divergence. Simple sequence repeat analyses on 498 individuals of 19 natural populations demonstrate that a significant genetic differentiation occurs among populations (mean F _ST = 0.578), and A. edgeworthii is a highly self-fertilized species (mean selfing rate s  = 0.989). The distribution pattern of genetic diversity in this species shows that central populations possess high genetic diversity (e.g. population WL with H _E = 0.673 and population JG with H _E = 0.663), whereas peripheral ones have a low H _E as in population JD (0.011). The morphological divergence of leaf shape was estimated by the elliptical Fourier analysis on the data from 11 natural and four common garden populations. Leaf morphology analyses indicate the morphological divergence does not show strong correlation with the genetic differentiation ( R  = 0.260, P  = 0.069). By comparing the 95% confidence interval of Q _ST with that of F _ST, Q _ST values for five out of 12 quantitative traits are significantly higher than the average F _ST value over eight microsatellite loci. The comparison of F _ST and Q _ST suggests that two kinds of traits can be driven by different evolutionary forces, and the population divergence in leaf morphology is shaped by local selections.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 505–516.     

Adaptive modifications of carapace outlines in the Cytheroidea (Ostracoda: Crustacea)

Shell outlines of 202 extant cytheroidean ostracods were analysed in dorsal, lateral, and posterior views by elliptic Fourier analysis. The results obtained confirm that the exterior morphology is related to ecological factors as well as phylogenetic constraints. Phytal species living on tall seagrass and benthic species burrowing in sediments are characterized and differentiated from the species crawling on sediments by the presence of slender shells with tapered venters. With reference to reconstruction of ancestral state of outline traits on the molecular phylogeny, the hypothetical ancestor of cytheroidean ostracods is presumed to have had an average-shaped shell. Morphological plasticity of the shell outline was observed in many families. The phytal species living on tall seagrass appear to have evolved convergently with species from other habitats, acquiring slim shell outlines during the Cenozoic period. The present analysis also reveals the phylogenetic constraints on the morphological evolution of the Trachyleberididae in their adaptation to a burrowing habit.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 810–821.     

Ecomorphology of Anolis lizards of the Choco' region in Colombia and comparisons with Greater Antillean ecomorphs

We analysed the ecomorphological relationships in four species of Anolis lizard that occur in the Choco' region in Colombia. The region is one of the most diverse of the Neotropical lowlands. The species were assigned to traditionally recognized Greater Antillean ecomorph categories based on habitat use data. Principal component analyses were carried out to examine correlations between the morphological traits, body size, and habitat use. We found that species are separated in morphological space principally by body size and lamella number. Upon removal of the effect of body size, correlations between morphology and habitat use became apparent. However, when compared with Greater Antillean ecomorphs, we found little evidence of morphological convergence in species occupying similar habitats. The species of the Choco' region are, however, clearly separated in the multidimensional morphological space from the Antillean taxa, and appear to form a separate cluster differentiating principally in body size and the number of lamellae. Mainland species clearly constitute an ecomorphological radiation but apparently this is independent of that of the West Indian fauna. More studies are needed to understand the causes for the independence of evolutionary trajectories on the mainland and the Greater Antilles, and to obtain a better understanding of the ecological and evolutionary processes underlying the radiation of these faunas.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 29–39.     

Exploring the causes of variation in phenology and morphology in Mediterranean geophytes: a genus-wide study of Cyclamen

The phenology and morphology of Mediterranean plants are constrained by drought in summer and cold temperatures in winter. In this study we examine how climatic factors and phylogenetic constraints have shaped variation in the phenology and morphology of 17 species of the genus Cyclamen cultivated in uniform garden conditions. We quantify the extent to which traits differ among subgenera and thus represent conserved traits within evolutionary lineages. We also explore whether leaf, flowering and seed-release phenology are correlated among species, and thus whether variation in flowering phenology results from selection on dispersal phenology. Our results show a significant influence of subgenus membership on leaf and flowering phenology but not on morphological traits or the timing of seed release. Among-species variation in foliage height, leaf size and seed mass (but not in floral traits) is correlated with chromosome number. Leaf traits show that species with a shorter vegetative period have a higher capacity for resource acquisition. Major phenological shifts, i.e. spring vs. autumn flowering and a decoupling of leaf and flower phenology in autumnal flowering species, thus occurred prior to the diversification of species in each subgenus and not as a response to selection on dispersal timing. Leaf and flowering phenology illustrate a gradient of strategies from autumn flowering in the absence of leaves (hysteranthous species) to spring flowering with fully developed foliage (synanthous species). In the former, flowering is uncoupled from resource acquisition by simultaneous photosynthesis, indicative that hysteranthy is a response to temporal unpredictability in the onset of rain after the summer drought. Our results support the idea that whereas leaf development is controlled primarily by moisture availability and secondarily by temperature, flowering is temperature dependent, above a minimum moisture threshold. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 145 , 469–484.     

Ecological diversity and adaptive tendencies in the tropical fern Trichomanes L. (Hymenophyllaceae) with special reference to climbing and epiphytic habits

Among the basal fern families, the Hymenophyllaceae, with more than 600 species, display a high diversity in terms of their morphology and the habitats that they occupy. We have chosen to focus on Trichomanes L., a clearly defined genus for which a phylogeny is presently being developed, to investigate the appearance of the climbing and epiphytic habits, as well as the related supposed adaptive characters. In this study we present the first review of the different ecological types within the genus: terrestrial, climbing (divided into hemi-epiphytic forms and true lianas), and epiphytic types. The study of several features concerning stem morphology and leaf size allows a proposal on relationships between ecology and plant morphology. Terrestrial species display a thick monocaulous rhizome with robust roots and short internodes. Climbing species are characterized by a branched, thick, creeping rhizome with long internodes. Epiphytic species also exhibit long, creeping and branching stems with long internodes but the rhizome is fine to filiform. Under these circumstances, there is a reduction of root system and frond size leading to dwarfism in numerous instances. This may be related to an extreme hygrophilous epiphytic strategy. Finally, hypotheses on the evolution of these habits and hence on the evolutionary relationships between ecology and characters are presented and discussed.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 41–63.     

Volatile leaf oil diversity in the narrow range endemic Eucalyptus argutifolia (Myrtaceae) and its widespread congener Eucalyptus obtusiflora

Variation in the qualitative composition of volatile leaf oil was examined in the rare Eucalyptus argutifolia and its widespread congener Eucalyptus obtusiflora . The results revealed that, consistent with the pattern seen with allozymes, E. argutifolia had less variation within populations than E. obtusiflora . Total leaf oil diversity was also significantly lower in the rare species. As found with allozymes, most leaf oil diversity was within populations, but there was also a significant proportion of the variation between populations (25.2% and 27.3% for E. argutifolia and E. obtusiflora , respectively). There were significant associations between phenotypic distance based on leaf oils and geographical distance and between phenotypic and genetic distance across all populations, but these associations were not evident within species. Factors leading to reduced variation in E. argutifolia appear to affect all types of variation, but the relationships between different types of variation within the species are less apparent.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 738–745.     

Morphological correlates of life‐history variation: is lizard clutch size related to the number of germinal beds in the ovary?

Clutch size varies widely in reptiles, both intraspecifically and interspecifically. The mechanisms that generate this variation have attracted detailed study, focusing primarily on ecological factors (e.g. food availability), trade‐offs with other traits (e.g. offspring size), and physical constraints (e.g. maternal body shape). Does ovarian morphology, specifically the number of germinal beds from which ova are produced, also correlate with clutch size? Our review of published data on 58 lizard species reveals that clutch size is correlated with the number of germinal beds per ovary (more fecund species have more germinal beds), and that phylogenetic changes in germinal beds have been consistently associated with concurrent phylogenetic changes in fecundity. These correlations imply a causal connection: either clutch size is constrained by ovarian morphology, and/or ovarian morphology evolves to allow adaptive shifts in clutch size. The latter hypothesis is more consistent with available data. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94 , 81–88.     

Phylogenetic and ecological effects on interspecific variation in structurally simple avian vocalizations

Flight calls are structurally simple avian vocalizations largely associated with sustained migratory flight. We used a multilocus phylogeny of 47 North American wood warblers (Aves: Parulidae) to quantify the extent of phylogenetic signal in flight-call spectrographic characteristics and to remove phylogenetic effects when testing for associations among flight-call attributes, behavioural characters related to migration strategies and ecological habitat variables. We also employed a quantile regression and null model approach to compare a matrix of interspecific phylogenetic divergence with indices of the corresponding acoustic differences derived from spectrographic measurements of flight calls. Nearly half of the measurements of flight-call properties exhibited significant associations with phylogeny. Controlling for phylogenetic effects, high-frequency flight calls were associated with species occupying taller and more open forest canopies. Ecological properties associated with migratory and winter distributions did not correlate with flight-call characteristics. Differences among the evolutionary histories of structural vs. signal properties of flightcalls suggest that phylogenetic and ecological effects are present. The evolution of flight-call syllable structure may involve selection for species recognition, whereas adaptation to the acoustic environment likely has influenced evolution of their spectral and temporal properties. More generally, the historical contribution to variation in behavioural characters is a long-standing source of debate; these results suggest that substantial phylogenetic effects may be present even in vocal traits that may be highly labile. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 155–173.