Showing papers in "Biological Journal of The Linnean Society in 2012"

Ecotypes and the controversy over stages in the formation of new species

Abstract: Recent interest in the role of ecology in species formation has led to renewed discussion of the stages in the process of speciation. Although attempts to classify the stages in the process of species formation date back at least as far as Alfred Russel Wallace, one of the most intense debates on the subject occurred among botanists during the mid-20th Century. The present review outlines the progression of the historical debate about stages in the evolution of species, which was instigated by the genecological classification scheme of Gote Turesson in the 1920s, championed in the mid-century by Jens Clausen, and then brought under harsh scrutiny by many in the 1960s and 1970s. At the heart of the controversy is the question of whether speciation occurs rapidly on a local scale or gradually through the formation of geographically widespread ecotypes that evolve as precursors to species. A corollary to this debate is the question of whether speciation is reversible and, if so, how does it become irreversible? A third wave of interest in stages in the process of speciation is currently underway, thus making a modern historical narrative of the debate important. Both contemporary and past evolutionary biologists have argued that viewing speciation as being composed of stages can free researchers from concerns over species definitions and focus attention on the mechanisms involved in the process. How speciation becomes irreversible and whether ecogeographically isolated ecotypes are integral to this process remain as important unresolved issues. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 241–257.

The subspecies concept in butterflies: has its application in taxonomy and conservation biology outlived its usefulness?

Abstract: Subspecies lie at the interface between systematics and population genetics, and represent a unit of biological organization in zoology that is widely used in the disciplines of taxonomy and conservation biology. In this review, we explore the utility of subspecies in relation to their application in systematics and biodiversity conservation, and briefly summarize species concepts and criteria for their diagnosis, particularly from an invertebrate perspective. The subspecies concept was originally conceived as a formal means of documenting geographical variation within species based on morphological characters; however, the utility of subspecies is hampered by inconsistencies by which they are defined conceptually, a lack of objective criteria or properties that serve to delimit their boundaries, and their frequent failure to reflect distinct evolutionary units according to population genetic structure. Moreover, the concept has been applied to populations largely comprising different components of genetic diversity reflecting contrasting evolutionary processes. We recommend that, under the general lineage (unified) species concept, the definition of subspecies be restricted to extant animal groups that comprise evolving populations representing partially isolated lineages of a species that are allopatric, phenotypically distinct, and have at least one fixed diagnosable character state, and that these character differences are (or are assumed to be) correlated with evolutionary independence according to population genetic structure. Phenotypic character types include colour pattern, morphology, and behaviour or ecology. Under these criteria, allopatric subspecies are a type of evolutionarily significant unit within species in that they show both neutral divergence through the effects of genetic drift and adaptive divergence under natural selection, and provide an historical context for identifying biodiversity units for conservation. Conservation of the adaptedness and adaptability of gene pools, however, may require additional approaches. Recent studies of Australian butterflies exemplify these points. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Cultural traditions and the evolution of reproductive isolation: ecological speciation in killer whales?

Abstract: Human evolution has clearly been shaped by gene–culture interactions, and there is growing evidence that similar processes act on populations of non-human animals as well. Recent theoretical studies have shown that culture can be an important evolutionary mechanism due to the ability of cultural traits to spread rapidly both vertically and horizontally, resulting in decreased within-group variance and increased between-group variance. Here, we collate the extensive literature on population divergence in killer whales (Orcinus orca) and argue that they are undergoing ecological speciation as a result of dietary specializations. While we cannot exclude the possibility that cultural divergence predates ecological divergence, we propose that cultural differences in the form of learned behaviors between ecologically-divergent killer whale populations have resulted in sufficient reproductive isolation in sympatry to lead to incipient speciation.

Patterns and processes in the evolutionary history of parrotfishes (Family Labridae)

Abstract: Phylogenetic reconstruction of the evolutionary relationships among 61 of the 70 species of the parrotfish genera Chlorurus and Scarus (Family Labridae) based on mitochondrial and nuclear gene sequences retrieved 15 well-supported clades with mid Pliocene/Pleistocene diversification. Twenty-two reciprocally monophyletic sister-species pairs were identified: 64% were allopatric, and the remainder were sympatric. Age of divergence was similar for allopatric and sympatric species pairs. Sympatric sister pairs displayed greater divergence in morphology, ecology, and sexually dimorphic colour patterns than did allopatric pairs, suggesting that both genetic drift in allopatric species pairs and ecologically adaptive divergence between members of sympatric pairs have played a role in diversification. Basal species typically have small geographical ranges and are restricted to geographically and ecologically peripheral reef habitats. We found little evidence that a single dominant process has driven diversification, nor did we detect a pattern of discrete, sequential stages of diversification in relation to habitat, ecology, and reproductive biology. The evolution of Chlorurus and Scarus has been complex, involving a number of speciation processes.

A framework for analysing colour pattern geometry: adjacent colours

Abstract: The analysis of colour pattern geometry is not as well advanced as the analysis of colour, although this reflects a lack of an analytical framework. The present study proposes an approach based on a consideration of which colours are adjacent to each other. Both vertebrate and invertebrate eyes do not take static images of the world but move across the field of view. As a consequence, the eye takes transects across the field of view responding to the colours and luminances within patches and to the colour and/or luminance transitions between patches. The framework and methods suggested here are based upon transects across colour patterns and make it possible to estimate colour pattern parameters that capture not only the relative areas of each patch class, but also the relative frequencies of colour/luminance transitions or adjacency. This allows tests of new hypotheses about colour patterns at the same time as including colour, pattern, and texture. Eleven groups of predictions are made with respect to the often conflicting needs of communication with conspecifics, avoiding predation, and finding food. New phenomena may be discovered as a result of these methods and predictions. For example, certain colour transitions may be used for species recognition even though the same colours are used by all species. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Evolutionary and biogeographical history of an ancient and global group of arachnids (Arachnida: Opiliones: Cyphophthalmi) with a new taxonomic arrangement

Abstract: We investigate the phylogeny, biogeography, time of origin and diversification, ancestral area reconstruction and large‐scale distributional patterns of an ancient group of arachnids, the harvestman suborder Cyphophthalmi. Analysis of molecular and morphological data allow us to propose a new classification system for the group; Pettalidae constitutes the infraorder Scopulophthalmi new clade, sister group to all other families, which are divided into the infraorders Sternophthalmi new clade and Boreophthalmi new clade. Sternophthalmi includes the families Troglosironidae, Ogoveidae, and Neogoveidae; Boreophthalmi includes Stylocellidae and Sironidae, the latter family of questionable monophyly. The internal resolution of each family is discussed and traced back to its geological time origin, as well as to its original landmass, using methods for estimating divergence times and ancestral area reconstruction. The origin of Cyphophthalmi can be traced back to the Carboniferous, whereas the diversification time of most families ranges between the Carboniferous and the Jurassic, with the exception of Troglosironidae, whose current diversity originates in the Cretaceous/Tertiary. Ancestral area reconstruction is ambiguous in most cases. Sternophthalmi is traced back to an ancestral land mass that contained New Caledonia and West Africa in the Permian, whereas the ancestral landmass for Neogoveidae included the south‐eastern USA and West Africa, dating back to the Triassic. For Pettalidae, most results include South Africa, or a combination of South Africa with the Australian plate of New Zealand or Sri Lanka, as the most likely ancestral landmass, back in the Jurassic. Stylocellidae is reconstructed to the Thai‐Malay Penisula during the Jurassic. Combination of the molecular and morphological data results in a hypothesis for all the cyphophthalmid genera, although the limited data available for some taxa represented only in the morphological partition negatively affects the phylogenetic reconstruction by decreasing nodal support in most clades. However, it resolves the position of many monotypic genera not available for molecular analysis, such as Iberosiro, Odontosiro, Speleosiro, Managotria or Marwe, although it does not place Shearogovea or Ankaratra within any existing family. The biogeographical data show a strong correlation between relatedness and formerly adjacent landmasses, and oceanic dispersal does not need to be postulated to explain disjunct distributions, especially when considering the time of divergence. The data also allow testing of the hypotheses of the supposed total submersion of New Zealand and New Caledonia, clearly falsifying submersion of the former, although the data cannot reject the latter. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 92–130.

Studying phenotypic plasticity: the advantages of a broad approach

Abstract: Phenotypic plasticity is traditionally defined as the capacity of a given genotype to render alternative phenotypes under different environmental conditions. Some studies focus on the individual genotype to study ‘true’ phenotypic plasticity, regardless of the level of ecological organization involved in each particular study. We argue that, depending on the research question and the scale, there are advantages of looking beyond the genetic identity of each individual phenotype when addressing phenotypic plasticity. This broad approach may simplify experimental designs, increase their statistical power, and allow a more inclusive estimation of the extent of phenotypic plasticity in natural populations. We also posit that when the focus is on the ecological significance of a given phenotype, the final ontogenetic stage and size of the experimental individuals whose plastic responses are compared should not be necessarily considered as confounding factors. A broad approach to the genotypic basis of phenotypic responses, focusing on the representativeness of the genotypic sample, together with the recognition that any environmentally-induced phenotypic change is legitimate plasticity (and potential target of natural selection), may contribute to the understanding of the ecological significance of phenotypic plasticity. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 1–7.

Convergence and divergence in the subterranean realm: a reassessment

Abstract: The dominant neo-Darwinian paradigm of the evolution of cave animals is that the severe aphotic, low food environment with little environmental cyclicity imposes strong selective pressures leading to a convergent (troglomorphic) morphology of reduced pigment and eyes, and elaborated extra-optic sensory structures. Challenges to the paradigm come from two fronts. First, troglomorphic animals occur in many aphotic habitats with relatively abundant food and environmental cyclicity. Second, many permanent reproducing populations in caves are not troglomorphic. A review of data on patterns of troglomorphy confirms both of these points. This suggests that the absence of light, rather than resource level and environmental cyclicity, is the important selective factor, and that other forces are at work, including competition and differences in the age of lineages in subterranean environments. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Palaeoclimatic models help to understand current distribution of Caucasian forest species

Abstract: Spatial and temporal constraints on dispersal explain the absence of species from areas with potentially suitable conditions. Previous studies have shown that post-glacial recolonization has shaped the current ranges of many species, yet it is not completely clear to what extent interspecific differences in range size depend on different dispersal rates. The inferred boundaries of glacial refugia are difficult to validate, and may bias spatial distribution models (SDMs) that consider post-glacial dispersal constraints. We predicted the current distribution of 12 Caucasian forest plants and animals, factoring in the effective geographical distance from inferred glacial refugia as an additional predictor. To infer glacial refugia, we tested the transferability of the current SDMs based on the distribution of climatic variables, and projected the most transferable ones onto two climate scenarios simulated for the Last Glacial Maximum (LGM). We then calculated least-cost distances from the inferred refugia, using elevation as a friction surface, and recalculated the current SDMs incorporating the distances as an additional variable. We compared the predictive powers of the initial with the final SDMs. The palaeoclimatic simulation that best matched the distribution of species was assumed to represent the closest fit to the true palaeoclimate. SDMs incorporating refugial distance performed significantly better for all but one studied species, and the Model for Interdisciplinary Research on Climate (MIROC) climatic simulation provided a more convincing pattern of the LGM climate than the Community Climate System Model (CCSM) simulation. Our results suggest that the projection of suitable habitat models onto past climatic conditions may yield realistic boundaries of glacial refugia, and that the current distribution of forest species in the study region is strongly associated with locations of former refugia. We inferred six major forest refugia throughout western Asia: (1) Colchis; (2) western Anatolia; (3) western Taurus; (4) the upper reaches of the Tigris River; (5) the Levant; and (6) the southern Caspian basin. The boundaries of the modelled refugia were substantially broader than the refugia boundaries inferred solely from pollen records. Thus, our method could be used to: (1) improve models of current species distributions by considering the dispersal histories of the species; and (2) validate alternative reconstructions of palaeoclimate with current distribution data. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 231‐248. ADDITIONAL KEYWORDS: forests ‐ fuzzy envelopes ‐ Mahalanobis distance ‐ post-glacial dispersal ‐ range modelling ‐ reconstruction of palaeoclimate ‐ variable selection ‐ western Asia.

Orchestrating the score: complex multimodal courtship in the Habronattus coecatus group of Habronattus jumping spiders (Araneae: Salticidae)

Abstract: Jumping spiders in the genus Habronattus use complex multimodal signals during courtship displays In the present study, we describe multimodal displays from the Habronattus coecatus clade, comprising a diverse group of 23 described species Habronattus coecatus group displays are made up of sex-specific ornamentation and temporally coordinated combinations of motion displays and vibratory songs Vibratory songs are complex, consisting of up to 20 elements organized in functional groupings (motifs) that change as courtship progresses This temporal structuring of displays is analogous to a musical composition Vibratory elements are associated with movement displays involving coloured and patterned ornaments on the male body We describe general patterns of multimodal displays for 11 species including one, Habronattus borealis, which appears to have lost complex display behaviour Habronattus coecatus group courtship is one of the most complex communication systems yet described in arthropods and this group may reveal important factors driving the evolution of complex signals © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 522–547

Testing historical explanations for gradients in species richness in heliconiine butterflies of tropical America

Abstract: We compiled a large database of 58 059 point locality records for 70 species and 434 subspecies of heliconiine butterflies and used these data to test evolutionary hypotheses for their diversification. To study geographical patterns of diversity and contact zones, we mapped: (1) species richness; (2) mean molecular phylogenetic terminal branch length; (3) subspecies richness and the proportion of specimens that were subspecific hybrids, and (4) museum sampling effort. Heliconiine species richness is high throughout the Amazon region and peaks near the equator in the foothills and middle elevations of the eastern Andes. Mean phylogenetic terminal branch length is lowest in the eastern Andes and tends to be low in species-rich areas. By contrast, areas of high subspecies richness, where subspecies overlap in range and/or hybridize, are concentrated along the course of the Amazon River, with the eastern Andes slopes and foothills relatively depauperate in terms of local intraspecific phenotypic diversity. Spatial gradients in heliconiine species richness in the Neotropics are consistent with the hypothesis that species richness gradients are driven at least in part by variation in speciation and/or extinction rates, resulting in observed gradients in mean phylogenetic branch length, rather than via evolutionary age or niche conservatism alone. The data obtained in the present study, coupled with individual case studies of recently evolved Heliconius species, suggest that the radiation of heliconiine butterflies occurred predominantly on the eastern slopes of the Andes in Colombia, Ecuador, and Peru, as well as in the upper/middle Amazon basin. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 479–497.

Morphological and thermal properties of mammalian insulation: the evolutionary transition to blubber in pinnipeds

Abstract: Carnivora includes three independent evolutionary transitions to the marine environment: pinnipeds (seals, sea lions, and walruses), sea otters, and polar bears. Among these, only the pinnipeds have retained two forms of insulation, an external fur layer and an internal blubber layer for keeping warm in water. In this study we investigated key factors associated with the transition to the use of blubber, by comparing blubber characteristics among the pinnipeds. Characteristics included gross morphology (blubber thickness), fat composition (fatty acid profiles, percentage lipid, and water), and thermal conductivity. Sea lions, phocids, and walrus, which have lower fur densities than fur seals, have thicker blubber layers than fur seals (P < 0.001). Comparisons of lipid content, water content, and fatty acid composition indicated significant differences in the composition of the inner and outer regions of the blubber between groups (P < 0.001), consistent with the hypothesis that phocids and sea lions utilize the outer layer of their blubber primarily for thermal insulation, and the inner layer for energy storage. Fur seals, by contrast, rely more on their fur for thermal insulation, and utilize their blubber layer primarily for energy storage. Comparing across carnivore species, differences in total insulation (fur and/or blubber) are influenced substantially by body size and habitat, and to a lesser extent by latitudinal climate. Overall, these results indicate consistent evolutionary trends in the transition to blubber and evidence for convergent evolution of thermal traits across lineages. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Genetic diversity and multiple origins of polyploid Atriplex nummularia Lindl. (Chenopodiaceae)

Abstract: Few studies have described the genetic diversity within and between populations of polyploid plant species despite the general acceptance of the importance of polyploidy in plant diversification and speciation. The genus Atriplex has a complex evolutionary history in Australia that has included polyploidy and hybridization among perennial forms. The octoploid, dioecious species Atriplex nummularia is proposed to have evolved from an octoploid ancestor in the coastal semi-arid fringe of south-western Australia, and to have spread east and diversified into taxa which occupy edaphically different habitats. Despite interest in the diversification of the genus, and the ecological and economic importance of A. nummularia, there are no descriptions of the genetic structure of the species. Nuclear microsatellite markers and principal coordinate analysis, analysis of molecular variance, Bayesian and phenetic analyses were used to investigate the diversity and taxonomic relationships of two common subspecies of A. nummularia. Genetic diversity was high overall (A = 509, A′ = 42.4, Ho = 0.824, H′ = 2.8), but values were significantly lower in the western subspecies, A. nummularia ssp. spathulata. As in other outbreeding, perennial species, most of the genetic diversity was within populations (FST = 0.125). Clear divergence of subspecies was evident in principal coordinate analysis, neighbor-joining and Bayesian clustering analyses and the differentiation of populations was very low within subspecies (FSC = 0.048). These findings support the taxonomic separation of the two subspecies. Clustering patterns based on Bayesian analyses suggested that the polyploid subspecies of A. nummularia have multiple origins. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 218–230.

Ancestral plasticity and allometry in threespine stickleback reveal phenotypes associated with derived, freshwater ecotypes

Abstract: For over a century, evolutionary biologists have debated whether and how phenotypic plasticity impacts the processes of adaptation and diversification. The empirical tests required to resolve these issues have proven elusive, mainly because it requires documentation of ancestral reaction norms, a difficult prospect where many ancestors are either extinct or have evolved. The threespine stickleback radiation is not limited in this regard, making it an ideal system in which to address general questions regarding the role of plasticity in adaptive evolution. As retreating ice sheets have exposed new habitats, oceanic stickleback founded innumerable freshwater populations, many of which have evolved parallel adaptations to their new environments. Because the founding oceanic population is extant, we can directly evaluate whether specific patterns of ancestral phenotypic expression in the context of novel environments (plasticity), or over ontogeny, predisposed the repeated evolution of “benthic” and “limnetic” ecotypes in shallow and deep lakes, respectively. Consistent with this hypothesis, we found that oceanic stickleback raised in a complex habitat and fed a macroinvertebrate diet expressed traits resembling derived, benthic fish. Alternatively, when reared in a simple environment on a diet of zooplankton, oceanic stickleback developed phenotypes resembling derived, limnetic fish. As fish in both treatments grew, their body depths increased allometrically, as did the size of their mouths, while their eyes became relatively smaller. Allometric trajectories were subtly but significantly impacted by rearing environment. Thus, both environmental and allometric influences on development, along with their interactive effects, produced variation in phenotypes consistent with derived benthic and limnetic fish, which may have predisposed the repeated genetic accommodation of this specific suite of traits. We also found significant shape differences between marine and anadromous stickleback, which has implications for evaluating the ancestral state of stickleback traits.

Twenty years of body shape evolution in a threespine stickleback population adapting to a lake environment

Abstract: Analysis of contemporary evolution can provide important insights into the pattern and rate of phenotypic evolution. The threespine stickleback population in Loberg Lake was exterminated in 1982, and a new population was founded between 1983 and 1989 by anadromous stickleback. The body shape of the Loberg Lake population resembled that of anadromous populations in 1990, although it had diverged markedly by 1992. Between 1992 and 2009, the population evolved more slowly to resemble typical lake populations in the region, diverging approximately 68% of the distance separating its putative ancestor and the original native population by 2009. Temporal evolution is the main source of variation, although spatial heterogeneity, armour phenotype, and allometry contribute significant variation. There was no significant effect of ancestral phenotypic shape covariance on the evolutionary trajectory of this population. Temporal variation in the Loberg Lake population provides a rare glimpse into the evolutionary response of a complex trait to natural selection after a major habitat shift. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 817–831.

Why are birds' eggs colourful? Eggshell pigments co‐vary with life‐history and nesting ecology among British breeding non‐passerine birds

Abstract: 657..672 The colourful appearance of bird eggshells has long fascinated biologists and considerable research effort has focused on the structure and biochemistry of the avian eggshell matrix. The presence of tetrapyrrole pigments was identified nearly a century ago. Surprisingly, how the concentrations of avian eggshell pigments vary among related species, and whether this variability is associated with either eggshell appearance and/or species life-history traits, remains poorly understood. We quantified the concentrations of the two key eggshell pigments, protoporphyrin IX and biliverdin, from a diverse sample of eggshells stored at the Natural History Museum, Tring, UK. We explicitly tested how these two pigments are associated with physical measures of eggshell coloration and whether the pigment concentrations and colour diversity co-vary with phylogenetic affiliations among species. We also tested a series of comparative hypotheses regarding the association between the concentrations of the two pigments and specific life-history and breeding ecology traits. Across species, the average concentrations of protoporphyrin and biliverdin were positively correlated, and both strongly co-varied with phylogenetic relatedness. Controlling for phylogeny, protoporphyrin concentration was associated with a higher likelihood of cavity nesting and ground nesting, whereas biliverdin concentration was associated with a higher likelihood of non-cavity nesting habit and bi-parental provisioning. Although unlikely to be explained by a single function, the breeding ecology and life history-dependence of eggshell pigment concentrations in these comparative analyses implies that related species share pigment strategies, and that those strategies relate to broad adaptive roles in the evolution of variation in avian eggshell coloration and its underlying mechanisms. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 657-672.

Miocene divergence, phenotypically cryptic lineages, and contrasting distribution patterns in common lichen-forming fungi (Ascomycota: Parmeliaceae)

Abstract: Despite the recent advancements in recognizing diversity in lichen-forming fungi, assessing the timing of diversification remains largely unexplored in these important fungal symbionts. To better understand the evolutionary processes driving diversification in common lichen-forming fungi, we investigated the phylogeny and biogeography of the broadly distributed Melanelixia fuliginosa/M. glabratula group, using molecular data from six nuclear markers. Phylogenetic analyses of individual gene alignments and combined data provide strong evidence for five species-level lineages within this species complex. Three of these lineages correspond to the previously described species M. fuliginosa, M. glabratula, and M. subaurifera. The remaining two lineages, ‘M. sp. 1’ and ‘M. sp. 2’, merit species recognition based on genealogical concordance. Both M. glabratula and M. subaurifera had broad intercontinental distributions, sharing identical haplotypes among intercontinental populations. Based on the current sampling, M. fuliginosa s.s. was represented exclusively by European material and was not collected in North America. ‘M. sp. 1’ was represented by collections from Scotland and Spain; and ‘M. sp. 2’ was represented by collections in California, USA. Environmental factors driving the contrasting distribution patterns in this group remain unknown. Divergence times estimated using a coalescence-based multilocus species-tree approach suggest that diversification within the M. fuliginosa/M. glabratula group occurred exclusively during the Miocene. The results of the present study indicate that phenotypically cryptic lichen-forming fungal species-level lineages may be relatively ancient and do not necessarily reflect recent divergence events. Furthermore, diagnosable phenotypic differences may be absent even millions of years after the initial divergence. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●●, ●●–●●.

Morphological and thermal properties of mammalian insulation: the evolution of fur for aquatic living

Abstract: Carnivora includes three independent evolutionary transitions to the marine environment: pinnipeds (seals, sea lions, and walruses), sea otters, and polar bears. All three lineages must contend with the thermal challenges of submersion in the marine environment. In the present study, we investigated changes in the fur associated with the transition from a terrestrial to an aquatic lifestyle, comparing fur characteristics among these lineages with those of semi-aquatic and strictly terrestrial carnivores. Characteristics included gross morphology (hair cuticle shape, circularity, length, and density) and thermal conductivity. We found consistent trends in hair morphology associated with aquatic living, such that marine carnivores have significantly flatter (P < 0.001), shorter (P < 0.001), and denser hairs (P < 0.001) than terrestrial carnivores. However, sea lions, phocids, and walrus, which have thicker blubber layers than fur seals, have lower fur densities than fur seals (P < 0.001). Species utilizing fur for insulation in water also showed an elongation of hair cuticle scales compared to terrestrial species and marine species relying on blubber for insulation (P < 0.001). By testing pelts under hydrostatic pressure, we determined that flattening of the hairs, cuticular scale elongation, and increased fur density are critical characteristics for maintaining an insulating air layer within the fur during submersion. Overall, these results indicate consistent evolutionary modifications to the fur associated with the transition to aquatic living, as well as a decrease in fur function associated with a greater reliance on blubber in some groups. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 926‐939. ADDITIONAL KEYWORDS: adaptation ‐ carnivora ‐ conductivity ‐ cuticle ‐ density ‐ guard hair ‐ hydrostatic pressure ‐ marine mammal ‐ morphology ‐ underhair.

Bacterial degradability of an intrafeather unmelanized ornament: a role for feather‐degrading bacteria in sexual selection?

Abstract: The impact of feather-degrading bacilli on feathers depends on the presence or absence of melanin. In vitro studies have demonstrated that unmelanized (white) feathers are more degradable by bacteria than melanized (dark) ones. However, no previous study has looked at the possible effect of feather-degrading bacilli on the occurrence of patterns of unmelanized patches on otherwise melanized feathers. The pied flycatcher Ficedula hypoleuca Pallas, 1764 is a sexually dimorphic passerine with white wing bands consisting of unmelanized patches on dark flight feathers. These patches are considered to be a sexually selected trait in Ficedula flycatchers, especially in males, where the patches are more conspicuous (larger and possibly whiter) than in females. Using in vitro tests of feather bacterial degradation, we compared the degradability of unmelanized and melanized areas of the same feather for 127 primaries collected from the same number of individuals in a population breeding in central Spain (58 males and 69 females). In addition, we also looked for sex differences in feather degradability. Based on honest signalling theory and on the fact that there is stronger sexual selection for males to signal feather quality than in females, we predicted that unmelanized areas should be more degradable by bacteria than melanized ones within the same feather, and that these unmelanized areas should also be more degradable in males than in females. We confirmed both predictions. Microstructural differences between cross-section dimensions of unmelanized and melanized barbs, but not differences in the density of barbs within unmelanized and melanized areas of feathers in males and females, could partly explain differences in degradability. This is the first study to show differences in bacterial degradability among markings on the same feather and among unmelanized feather patches between males and females as predicted by sexual selection theory. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 409–419.

Evolutionary geographic relationships among orthocladine chironomid midges from maritime Antarctic and sub‐Antarctic islands

Abstract: Two species of chironomid midges are currently described in the genus Belgica Jacobs, 1900. Belgica antarctica Jacobs, 1900 is endemic to parts of the maritime Antarctic, and Belgica albipes (Seguy, 1965) is endemic to Iles Crozet, a sub-Antarctic archipelago in the southern Indian Ocean. The relationships between these species, and their closest known relative (Eretmoptera murphyi Schaeffer, 1914, endemic to sub-Antarctic South Georgia), were examined by sequencing DNA fragments for domains 1 and 3–5 of 28S ribosomal DNA and the mitochondrial gene cytochrome c oxidase 1 (cox1). The resulting molecular relationships between the three species were unclear, although their position within the subfamily Orthocladiinae of the Chironomidae, as generated by classical taxonomy, was confirmed. Our data reinforce earlier doubts, based on classical morphological approaches, that the generic placement of E. murphyi may be incorrect. Further analyses may indeed confirm that the species represents a third member of the genus Belgica. Genetic distance analysis, limited to the barcode region of cox1, indicated high differentiation between the two populations of B. albipes sampled (one obtained from the type location), suggesting the likely presence of cryptic species within this taxon, and that the taxonomic status of this species should be revised. Analysis of cox1 sequences in B. antarctica highlighted a strong genetic structure between populations obtained from 12 locations along the Antarctic Peninsula and the South Shetland Islands archipelago, with a number of distinctive mtDNA lineages inhabiting geographically distinct areas. In particular, we found four different haplogroups constituting geographically close but genetically distinct populations, a pattern likely to have been encouraged by the brachyptery of the members of this genus. We suggest that the different genetic patterns shown by each haplogroup have probably been determined by historical dispersal and colonization events during the Pleistocene, and are consistent with their survival in refuges in situ during successive glacial maxima over this period.

Are the liverworts really that old? Cretaceous origins and Cenozoic diversifications in Lepidoziaceae reflect a recurrent theme in liverwort evolution

Abstract: Estimating the temporal origins of lineage diversity adds an important dimension to understanding diversity generating processes. In lineages with a sparse fossil record, molecular phylogenetic methods provide a means for estimating divergence times. In the present study, we use publicly available sequence data from the chloroplast genome of liverworts to simultaneously estimate significant divergence dates across all classes and orders of liverworts (Marchantiophyta). We show that, although there is great potential in synthetic dating analyses of sequence data, missing sequences can reduce the reliability of estimates, and that calibration priors should be interpreted with caution. Using the liverwort dataset as a broad outgroup, we obtain the first divergence time estimates for a large family of leafy liverworts; the Lepidoziaceae (Jungermanniidae). The Lepidoziaceae originated in the early Cretaceous with subsequent establishment of main lineages in the late Cretaceous. Divergence time estimates are consistent with Cenozoic diversification in Lepidozia, Telaranea, and Bazzania. Evidence was found for similar patterns of ancient origins followed by Cenozoic diversification in Ricciaceae (Marchantiopsida), Pelliaceae and Fossombroniaceae (Pelliidae), and Metzgeriaceae (Metzgeriidae), and adds to reports of similar patterns in Lejeuneaceae (Jungermanniidae, Porellales), and Plagiochilaceae (Jungermaniidae, Jungermanniales). The liverworts might be the living relatives of one of the earliest groups of land plants, but much of the extant diversity has evolved in the Cenozoic. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••‐••.

Testing the ‘Pleistocene species pump’ in alpine habitats: lineage diversification of flightless ground beetles (Coleoptera: Carabidae: Nebria) in relation to altitudinal zonation

Abstract: 95..111 Alpine species often have similar demographic responses to Pleistocene climate changes, but exhibit different spatial patterns of genetic diversity. Using a comparative phylogeographical approach, we examined the factors influencing lineage formation in three alpine carabid beetles of the genus Nebria Latreille inhabiting the California Sierra Nevada. These flightless beetles differ in altitudinal zonation and habitat preferences, but overlap spatially, have limited dispersal capacities and share life history characteristics. Species distribution modelling predicted decreasing population connectivity in relation to increasing altitudinal preferences. Diversity patterns at the cytochrome oxidase subunit I gene revealed north–south genetic structure and recent population growth in all three species. The high-elevation-restricted species, Nebria ingens Horn, exhibited a deep phylogeographical split, morphological divergence and evidence of limited, unidirectional gene flow towards the south. This was supported by additional data from three nuclear genes and isolation with migration analysis. Nebria spatulata Van Dyke, inhabiting an intermediate altitudinal range, exhibited fixed morphological differences between northern and southern populations, but showed limited structure. The broadly distributed Nebria ovipennis LeConte showed less structure and lacked morphological variation. Diversification of these Nebria species supports the role of altitudinal zonation in lineage formation and is consistent with the Pleistocene species pump model. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 107, 95–111.

Climatic oscillations shape the phylogeographical structure of Atlantic Forest fire‐eye antbirds (Aves: Thamnophilidae)

Abstract: In the present study, mitochondrial (mt)DNA sequence data were used to examine the genetic structure of fire-eye antbirds (genus Pyriglena) along the Atlantic Forest and the predictions derived from the river hypothesis and from a Last Glacial Maximum Pleistocene refuge paleomodel were compared to explain the patterns of genetic variation observed in these populations. A total of 266 individuals from 45 populations were sampled over a latitudinal transect and a number of phylogeographical and population genetics analytical approaches were employed to address these questions. The pattern of mtDNA variation observed in fire-eye antbirds provides little support for the view that populations were isolated by the modern course of major Atlantic Forest rivers. Instead, the data provide stronger support for the predictions of the refuge model. These results add to the mounting evidence that climatic oscillations appear to have played a substantial role in shaping the phylogeographical structure and possibly the diversification of many taxa in this region. However, the results also illustrate the potential for more complex climatic history and historical changes in the geographical distribution of Atlantic Forest than envisioned by the refuge model. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 900–824.

Climate and refugial origin influence the mitochondrial lineage distribution of weasels (Mustela nivalis) in a phylogeographic suture zone

Abstract: Overarching trends can be seen in European mammalian phylogeography, yet it is clear that species responded differently depending on adaptations to past environments. We built upon previous work on the phylogeography of weasels (Mustela nivalis) in Europe by using well-preserved museum specimens from a proposed phylogeographic suture zone. The complete cytochrome b gene was amplified from 49 individuals from present-day Poland and analyzed with previously published data on a European scale to identify glacial refugia and infer recolonization processes. Bayesian coalescent analysis revealed the importance of the Last Glacial Maximum and the Younger Dryas in the diversification of, and demographic changes in, identified mitochondrial lineages. Our analysis, in conjunction with the available fossil data, strongly points to a Carpathian origin for one of the lineages, and further highlights the importance of this region as a refugium for European mammals. Mustela nivalis originating from this refugium appear to have a selective advantage over M. nivalis from other lineages in certain environments in the suture zone in central Europe, with climate clearly influencing the distribution of mitochondrial DNA lineages. This has important implications not only for our understanding of how past climatic events shaped the genetic architecture of species, but also how they will respond to current and future climatic changes. (c) 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 5769.

Tracing the origins of widespread highland species: a case of Neogene diversification across the Mexican sierras in an endemic lizard

Abstract: The evolutionary history of the Mexican sierras has been shaped by various geological and climatic events over the past several million years. The relative impacts of these historical events on diversification in highland taxa, however, remain largely uncertain owing to a paucity of studies on broadly-distributed montane species. We investigated the origins of genetic diversification in widely-distributed endemic alligator lizards in the genus Barisia to help develop a better understanding of the complex processes structuring biological diversity in the Mexican highlands. We estimated lineage divergence dates and the diversification rate from mitochondrial DNA sequences, and combined divergence dates with reconstructions of ancestral geographical ranges to track lineage diversification across geography through time. Based on our results, we inferred ten geographically structured, well supported mitochondrial lineages within Barisia. Diversification of a widely-distributed ancestor appears tied to the formation of the Trans-Mexican Volcanic Belt across central Mexico during the Miocene and Pliocene. The formation of filter barriers such as major river drainages may have later subdivided lineages. The results of the present study provide additional support for the increasing number of studies that suggest Neogene events heavily impacted genetic diversification in widespread montane taxa. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 382‐394.

Cranial distinctiveness in the Apennine brown bear: genetic drift effect or ecophenotypic adaptation?

Abstract: Molecular studies highlighted a strong genetic affinity between the remnant and isolated population of theApennine brown bear and other southern European populations. Despite this genetic closeness a recent morpho-metric study revealed a marked phenotypic distinctiveness of the Apennine population, supporting the reinstate-ment of a distinct taxon (

The effect of coloration and temperature on sprint performance in male and female wall lizards

Abstract: Phenotypic coloration in animals is often expected to have a signalling function, but it may also evolve as a correlated trait that reflects life-history strategy, social strategy, or ecological divergence. Wall lizards (Podarcis muralis) exhibit substantial colour variation, with both males and females being red, white, yellow, or a mixture of these colours. However, the biological significance of these colour morphs remains unknown. Here we investigate the relationship between coloration and temperature-dependent locomotor performance in an attempt to identify the adaptive significance of colour variation in this species. We investigate the maximum sprint speed of males and females of each of these colour morphs across seven different temperatures, using general additive mixed models (GAMMs). We predicted that the different sexes and colour phenotypes would exhibit differences in sprint speed performance, potentially indicating a correlation between coloration and adaptation into different ecological niches. We found no difference in performance of the discrete colour morphs, but amongst individuals that exhibited red coloration, those with a greater percentage of red were slower than those with less red coloration. This suggests a trade-off between red coloration and high sprint performance in this species. Furthermore, larger animals performed better, independent of colour and sex. Finally, we found no relative or absolute difference between males and females in their sprint performance. Taken together, our results suggest that there is no sex-specific or colour morph-specific differentiation in the use of microhabitats in this species. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 107, 573–582.