Showing papers in "Biological Journal of The Linnean Society in 2009"
TL;DR: Bayesian and maximum likelihood analyses strongly support a principal division of Meliponini into Old and New World groups, with the Afrotropical+Indo-Malay/Australian clades comprising the sister group to the large Neotropical clade.
Abstract: Stingless bees (Meliponini) are one of only two highly eusocial bees, the other being the well studied honey bee (Apini). Unlike Apini, with only 11 species in the single genus Apis, stingless bees are a large and diverse taxon comprising some 60 genera, many of which are poorly known. This is the first attempt to infer a phylogeny of the group that includes the world fauna and extensive molecular data. Understanding the evolutionary relationships of these bees would provide a basis for behavioural studies within an evolutionary framework, illuminating the origins of complex social behaviour, such as the employment of dance and sound to communicate the location of food or shelter. In addition to a global phylogeny, we also provide estimates of divergence times and ancestral biogeograhic distributions of the major groups. Bayesian and maximum likelihood analyses strongly support a principal division of Meliponini into Old and New World groups, with the Afrotropical+Indo-Malay/Australian clades comprising the sister group to the large Neotropical clade. The meliponine crown clade is inferred to be of late Gondwanan origin (approximately 80 Mya), undergoing radiations in the Afrotropical and Indo-Malayan/ Australasian regions, approximately 50‐60 Mya. In the New World, major diversifications occurred approximately 30‐40 Mya. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 206‐232. ADDITIONAL KEYWORDS: Apidae ‐ biogeography ‐ corbiculate bees ‐ fossils ‐ Gondwana ‐ Hymenoptera ‐ molecular phylogenetics.
265 citations
TL;DR: The results obtained show that migration affects the shape of both front and hind wings, and suggest that mate guarding behaviour may also have an effect, especially on the front wing, which is interesting when compared with the geographically widespread and ecologically diverse dipterans Acalyptratae.
Abstract: Although, in some insect taxa, wing shape is remarkably invariant, the wings of Anisopteran dragonflies show considerable variation among genera. Because wing shape largely determines the high energetic costs of flight, it may be expected that interspecific differences are partly due to selection. In the present study, we examined the roles of long-distance migration and high-manoeuvrability mate guarding in shaping dragonfly wings, using a phylogeny-based comparative method, and geometric morphometrics to quantify wing shape. The results obtained show that migration affects the shape of both front and hind wings, and suggest that mate guarding behaviour may also have an effect, especially on the front wing. These effects on front wing shape are at least partly independent. Our findings are interesting when compared with the geographically widespread and ecologically diverse dipterans Acalyptratae (including the genus Drosophila). The wings in that group are similar in function and structure, but show strikingly low levels of interspecific variation.
127 citations
TL;DR: The limited empirical evidence supporting the idea that masquerade functions to cause misidentification of organisms is discussed, a testable definition of masquerade is provided, and how masquerade evolved and under what ecological conditions is suggested.
Abstract: Many organisms appear to mimic inanimate objects such as twigs, leaves, stones, and bird droppings. Such adaptations are considered to have evolved because their bearers are misidentified as either inedible objects by their predators, or as innocuous objects by their prey. In the past, this phenomenon has been classified by some as Batesian mimicry and by others as crypsis, but now is considered to be conceptually different from both, and has been termed 'masquerade'. Despite the debate over how to classify masquerade, this phenomenon has received little attention from evolutionary biologists. Here, we discuss the limited empirical evidence supporting the idea that masquerade functions to cause misidentification of organisms, provide a testable definition of masquerade, and suggest how masquerade evolved and under what ecological conditions.
121 citations
TL;DR: The results obtained depict a complex evolutionary scenario and emphasize the importance of considering multiple traits when disentangling the forces behind allopatric divergence in the Amazonian frog, Allobates femoralis.
Abstract: Evolutionary divergence in behavioural traits related to mating may represent the initial stage of speciation. Direct selective forces are usually invoked to explain divergence in mate-recognition traits, often neglecting a role for neutral processes or concomitant differentiation in ecological traits. We adopted a multi-trait approach to obtain a deeper understanding of the mechanisms behind allopatric divergence in the Amazonian frog, Allobates femoralis. We tested the null hypothesis that geographic distance between populations correlates with genetic and phenotypic divergence, and compared divergence between mate-recognition (acoustic) and ecological (coloration, body-shape) traits. We quantified geographic variation in 39 phenotypic traits and a mitochondrial DNA marker among 125 individuals representing eight populations. Geographic variation in acoustic traits was pronounced and tracked the spatial genetic variation, which appeared to be neutral. Thus, the evolution of acoustic traits tracked the shared history of the populations, which is unexpected for pan-Amazonian taxa or for mate-recognition traits. Divergence in coloration appeared uncorrelated with genetic distance, and might be partly attributed to local selective pressures, and perhaps to Batesian mimicry. Divergence in body-shape traits was low. The results obtained depict a complex evolutionary scenario and emphasize the importance of considering multiple traits when disentangling the forces behind allopatric divergence. ©2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 826-838.
121 citations
TL;DR: In this article, the association between craniodental shape and prey size among 35 species of living felids was explored using linear morphometrics of the crania, mandible and dentition.
Abstract: In the present study, we used linear morphometrics of the crania, mandible and dentition to explore the association between craniodental shape and prey size among 35 species of living felids. To accomplish this, felids were divided into three prey-size groups: (1) large prey specialists; (2) small prey specialists; and (3) mixed prey feeders. From these linear measurements, large prey specialist felids can be distinguished from small and mixed prey feeders by their relatively robust canines and incisors and relatively wide muzzles. These cranial characters are advantageous when dispatching large prey, due to the stranglehold that cats employ during this activity. Robust canines resist the bending and torsional forces applied by struggling prey and a wider muzzle helps to stabilize grip and distribute bite forces more evenly during the killing bite. Small prey specialists had smaller canines, narrower muzzles and slightly longer jaws for a speed advantage when catching small, quick prey. Mixed prey feeders were intermediate between large and small prey specialists, indicating they are adapted to killing both sizes of prey. Given the success of this ecomorphological analysis of living felids that specialize on different prey sizes, we look forward to applying this same approach to extinct species. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 784–799.
116 citations
TL;DR: The evidence better supports the possibility that the two species are older and mtDNA has recently introgressed between them, most likely as a result of a selective sweep, and could have important implications for the fields of phylogeography and taxonomy.
Abstract: 3 In studies of phylogeography and taxonomy, strong emphasis is usually placed on the study of mitochondrial (mt)DNA. In the present study, we present a remarkable case in which highly phenotypically divergent species have almost no divergence in mtDNA. Yellowhammers (Emberiza citrinella Linnaeus) and pine buntings (Emberiza leucocephalos S. G. Gmelin) differ noticeably in appearance and song but hybridize in some areas of contact. They share a variety of closely-related mtDNA haplotypes, with little divergence in frequencies, indicating a mitochon- drial divergence time sometime during or after the last major glacial period. By contrast, nuclear DNA (amplified fragment length polymorphism markers and CHD1Z gene sequences) differs more strongly between the species, and these differences can be used to identify intermediate genetic signatures of hybrids. The combined amount of mitochondrial diversity within yellowhammers and pine buntings is very low compared to other Emberiza species pairs, whereas the level of variation at the nuclear gene CHD1Z is comparable to that within other species pairs. Although it is difficult to completely reject the possibility that the two species split extremely recently and experienced rapid nuclear and phenotypic differentiation, we argue that the evidence better supports another possibility: the two species are older and mtDNA has recently introgressed between them, most likely as a result of a selective sweep. Mismatches between mitochondrial and nuclear phylogeographic patterns may occur more commonly than previously considered, and could have important implications for the fields of phylogeography and taxonomy. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 422-438. ADDITIONAL KEYWORDS: AFLP - CHD1Z - hybridization - mtDNA - phylogeography - Siberia - speciation.
115 citations
TL;DR: Honey bee pollination of Pouteria (Sapotaceae) plausibly augmented the native bees’ primary pollen resource and prevented their decline, but Invasive generalist pollinators may, however, cause specialized competitors to fail, especially in less biodiverse environments.
Abstract: Little is known of the potential coevolution of flowers and bees in changing, biodiverse environments. Female solitary bees, megachilids and Centris, and their nest pollen provisions were monitored with trap nests over a 17-year period in a tropical Mexican biosphere reserve. Invasion by feral Apis (i.e. Africanized honey bees) occurred after the study began, and major droughts and hurricanes occurred throughout. Honey bee competition, and ostensibly pollination of native plants, caused changes in local pollination ecology. Shifts in floral hosts by native bees were common and driven by plant phylogenetics, whereby plants of the same families or higher taxa were substituted for those dominated by honey bees or lost as a result of natural processes. Two important plant families, Anacardiaceae and Euphorbiaceae, were lost to competing honey bees, but compensated for by greater use of Fabaceae, Rubiaceae, and Sapotaceae among native bees. Natural disasters made a large negative impact on native bee populations, but the sustained presence of Africanized honey bees did not. Over 171 plant species comprised the pollen diets of the honey bees, including those most important to Centris and megachilids (72 and 28 species, respectively). Honey bee pollination of Pouteria (Sapotaceae) plausibly augmented the native bees’ primary pollen resource and prevented their decline. Invasive generalist pollinators may, however, cause specialized competitors to fail, especially in less biodiverse environments. No claim to original US government works. Journal compilation © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 152–160.
108 citations
TL;DR: The results obtained indicate that the Old and New World ampullariids are reciprocally monophyletic with probable Gondwanan origins, and that defining the sister group of the Ampullariidae and clarifying relationships among basal caenogastropods will require increased taxon sampling within these four families, and synthesis of both morphological and molecular data.
Abstract: Apple snails (Ampullariidae) are a diverse family of pantropical freshwater snails and an important evolutionary link to the common ancestor of the largest group of living gastropods, the Caenogastropoda. A clear understanding of relationships within the Ampullariidae, and identification of their sister taxon, is therefore important for interpreting gastropod evolution in general. Unfortunately, the overall pattern has been clouded by confused systematics within the family and equivocal results regarding the family's sister group relationships. To clarify the relationships among ampullariid genera and to evaluate the influence of including or excluding possible sister taxa, we used data from five genes, three nuclear and two mitochondrial, from representatives of all nine extant ampullariid genera, and species of Viviparidae, Cyclophoridae, and Campanilidae, to reconstruct the phylogeny of apple snails, and determine their affinities to these possible sister groups. The results obtained indicate that the Old and New World ampullariids are reciprocally monophyletic with probable Gondwanan origins. All four Old World genera, Afropomus, Saulea, Pila, and Lanistes, were recovered as monophyletic, but only Asolene, Felipponea, and Pomella were monophyletic among the five New World genera, with Marisa paraphyletic and Pomacea polyphyletic. Estimates of divergence times among New World taxa suggest that diversification began shortly after the separation of Africa and South America and has probably been influenced by hydrogeological events over the last 90 Myr. The sister group of the Ampullariidae remains unresolved, but analyses omitting certain outgroup taxa suggest the need for dense taxonomic sampling to increase phylogenetic accuracy within the ingroup. The results obtained also indicate that defining the sister group of the Ampullariidae and clarifying relationships among basal caenogastropods will require increased taxon sampling within these four families, and synthesis of both morphological and molecular data. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 61–76.
105 citations
TL;DR: The hypothesis that hosts shifts have led to speciation in the Enchenopa binotata species complex of treehoppers in part through their influence on divergence in mate communication systems is supported.
Abstract: A combination of divergent natural and sexual selection is a powerful cause of speciation. This conjunction of evolutionary forces may often occur when divergence is initiated by ecological differences between populations because local adaptation to new resources can lead to changes in sexual selection. The hypothesis that differences in resource use contribute to the evolution of reproductive isolation by altering the nature of sexual selection predicts that: (1) differences in sexual traits, such as signals and preferences, are an important source of reproductive isolation between species using different resources; (2) there are identifiable sources of selection on sexual traits that differ between species using different resources; and (3) signals vary between populations using different resources to a larger extent than between populations using the same resource at different localities. Testing these predictions requires a group of closely-related species or populations that specialize on different resources and for which the traits involved in mate choice are known. The Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae) are host plant specialists in which speciation is associated with shifts to novel host plants. Mating in this complex is preceded by an exchange of vibrational signals transmitted through host plant stems, and the signal traits important for mate choice have been identified. In the E. binotata complex, previous work has supported the first two predictions: (1) signal differences between species are important in mate recognition and (2) host shifts can alter both the trait values favoured by sexual selection and the evolutionary response to that selection. In the present study, we tested the last prediction by conducting a large-scale study of mating signal variation within and between the 11 species in the complex. We find that differences in host use are strongly associated with differences in signal traits important for mate recognition. This result supports the hypothesis that hosts shifts have led to speciation in this group in part through their influence on divergence in mate communication systems. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 60–72.
99 citations
TL;DR: The combined results of the present study indicate that these two strains belong to different biological entities within the proposed A. fraterculus complex.
Abstract: It has long been proposed that the nominal species Anastrepha fraterculus is a species complex and earlier studies showed high levels of pre-zygotic isolation between two laboratory strains from Argentina and Peru. Further experiments were carried out on the same populations and on their reciprocal hybrids, including pre- and post-zygotic isolation studies, pheromone analysis, and mitotic and polytene chromosome analysis. A high level of pre-zygotic isolation had been maintained between the parental strains despite 3 years of laboratory rearing under identical conditions. The level of pre-zygotic isolation was reduced in matings with hybrids. There were also differences in other components of mating behaviour. There were quantitative and qualitative differences in the sex pheromone of the two strains with the hybrids producing a mixture. The pre-zygotic isolation barriers were complemented by high levels of post-zygotic inviability and sex ratio distortion, most likely not due to Wolbachia, although there was evidence of some cytoplasmic factor involved in sex ratio distortion. Analysis of polytene chromosomes revealed a high level of asynapsis in the hybrids, together with karyotypic differences between the parental strains. The combined results of the present study indicate that these two strains belong to different biological entities within the proposed A. fraterculus complex.
99 citations
TL;DR: The study shows that the cryptic diversity uncovered among bats continues to increase as more regions are studied, and that the general pattern in the degree of permeability of the Straits of Gibraltar for bats is not found.
Abstract: Genetic divergence in bat communities was assessed on both sides of the Straits of Gibraltar and cryptic diversity was examined. Screening was carried out using partial sequences of the mitochondrial (mt)DNA cytochrome b gene on 399 individual bats belonging to the 18 species found on both sides of the Straits of Gibraltar. For those bats that showed important genetic discontinuities, molecular markers (ND1 and nuclear RAG2 genes) were added to expand the sampling process. Phylogenetic reconstructions were obtained using maximum parsinomy, genetic distances, maximum likelihood, and Bayesian criteria. As an estimate of bats’ flight performance, we measured for each species the wing aspect ratio and wing loading indexes, and correlated them with the maximum pairwise genetic distances obtained between southern Iberian and northern Moroccan populations. Genetic mtDNA distances between populations on both continents exceed 5% in seven out of 18 bat species analysed and unknown lineages were uncovered within the species complexes Myotis nattereri and Myotis mystacinus. We did not find a general pattern in the degree of permeability of the Straits of Gibraltar for bats. Genetic distances were not correlated with the ability to cross the Straits. Our study shows that the cryptic diversity uncovered among bats continues to increase as more regions are studied. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 434–450. ADDITIONAL KEYWORDS: community – cryptic diversity – cytochrome b – dispersal – genetic differentiation – mitochondrial DNA – ND1 – RAG2 – phylogeography – Pleistocene.
TL;DR: The hypothesis that geological events may play important roles in driving biological diversification through continental radiation in the past is supported.
Abstract: Increasing evidence suggests that geological or climatic events in the past triggered the radiative diversification of both animals and plants on islands as well as continents. The Qinghai-Tibetan Plateau (QTP) has been extensively uplifted since the Miocene, but there is little information on possible links between these events and biological diversification in this and adjacent regions. Partly to explore such links, we have examined the diversification of Saussurea (Asteraceae: Cardueae), a species-rich genus that is mostly endemic to QTP, but also occurs in arid highlands elsewhere in the Northern Hemisphere. The phylogenetic analyses were conducted on the basis of the nuclear (internal transcribed spacer, ITS) and plastid (trnL-F and psbA-trnH) sequences from 55 species, representing 19 sections from all six subgenera of Saussurea, and species from 15 genera of the Cardueae. The results suggest that the currently circumscribed genus Saussurea (s.l.) is a polyphyletic group and that five sections should be excluded from the genus. Samples from the other 14 sections (representing five subgenera) clustered as a monophyletic group (here designated the Saussurea s.s. lineage, SSSL) with high statistical support. However, none of the analyses (nuclear, plastid or combined) resolved SSSL's infrageneric phylogeny, and the parallel clades of the lineage indicate that island-like adaptive radiation occurred. Furthermore, this radiation appears to have occurred 14-7 Mya, during the period of the major uplift events of QTP. Thus, our results support the hypothesis that geological events may play important roles in driving biological diversification through continental radiation. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 893-903.
TL;DR: The reef building vermetid gastropod Dendropoma petraeum inhabits the warmest waters of the Mediterranean Sea and is considered a threatened marine species, and its genetic structure throughout its whole distribution range is characterized using mitochondrial and nuclear sequence data.
Abstract: The reef building vermetid gastropod Dendropoma petraeum inhabits the warmest waters of the Mediterranean Sea and is considered a threatened marine species. The aim of this study was to characterize its genetic structure throughout its whole distribution range using mitochondrial and nuclear sequence data. Because of its sessile adult lifestyle and lack of a pelagic larval stage, we expected a markedly subdivided population structure with limited levels of gene flow. Fragments of the mitochondrial genes cytochrome c oxidase subunit I (COI) and 16S rRNA (16S), were sequenced, along with the nuclear ribosomal cluster (internal transcribed spacer; ITS) in specimens from 18 localities. Our analyses identified four highly distinct phylogroups separated by a mean divergence of > 14% according to the COI sequence data or > 9% according to 16S, but differing only slightly in morphology. The nuclear data (ITS) indicated a lower substitution rate (divergence among groups of around 1%). These large genetic distances among the four lineages clearly point to the existence of a cryptic species complex within D. petraeum comprising at least four species. Differences in the characteristics of intracapsular larval development and protoconch were also detected among these lineages. The allopatric distribution of these cryptic species supports a predominantly vicariant-based cladogenetic pattern for the genus Dendropoma in the Mediterranean. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 898–912.
TL;DR: There have been many transitions in the number of mating types, and the requirement of nuclear reorganization may be a more important factor than genetic exchange in determining the optimum number of mate types in a species.
Abstract: Ciliates are a diverse group of microbial eukaryotes that exhibit tremendous variety in several aspects of their mating systems. To understand the evolutionary forces driving mating system diversification in ciliates, we use a comparative approach synthesizing data from many ciliate species in light of recent phylogenetic analyses. Specifically, we investigate the evolution of number of mating types, mode of mating type inheritance, and the molecular determinants of mating types across the taxonomic diversity of ciliates, with an emphasis on three well-studied genera: Tetrahymena, Paramecium, and Euplotes. We find that there have been many transitions in the number of mating types, and that the requirement of nuclear reorganization may be a more important factor than genetic exchange in determining the optimum number of mating types in a species. We also find that the molecular determinants of mating types and mode of inheritance are evolving under different constraints in different lineages of ciliates. Our results emphasize the need for further detailed examination of mating systems in understudied ciliate lineages. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 187‐197.
TL;DR: Analysis of the pattern of genetic variation in the great tit in 12 parks in central Barcelona and in an adjacent forest population using microsatellites found a significant genetic differentiation among the parks, with a structure that only partly reflected the geographic position of the parks.
Abstract: The increase of urban areas has led to a fragmentation of habitats for many forest-living species. Man-made parks might be a solution, but they can also act as sinks that are unable to maintain themselves without immigration from natural areas. Alternatively, parks might act as true metapopulations with extinctions and colonizations. In both cases, we can expect genetic variation to be reduced in the parks compared to the natural habitat. A third alternative is that the parks have sufficient reproduction to maintain themselves. To test these hypotheses, we analysed the pattern of genetic variation in the great tit (Parus major) in 12 parks in central Barcelona, and in an adjacent forest population using microsatellites. Genetic variation was not lower in the parks compared to the forest population, but larger, and gene flow was higher from the town to the forest compared to vice versa. We found a significant genetic differentiation among the parks, with a structure that only partly reflected the geographic position of the parks. Relatedness among individuals within parks was higher than expected by chance, although we found no evidence of kin groups. Assignment tests suggest that some parks are acting as net donors of individuals to other parks.
TL;DR: It is shown that territorial male collared lizards with greater bite-force capacity sire more offspring than weaker biting rivals but exhibit no survival advantage, and sexual selection on weapon performance appears to be a force driving the evolution and maintenance of sexual dimorphism in head shape.
Abstract: Weapons used in combat between males are usually attributed to sexual selection, which operates via a fitness advantage for males with weapons of better ‘quality’ Because the performance capacity of morphological traits is typically considered the direct target of selection, Darwin’s intrasexual selection hypothesis can be modified to predict that variation in reproductive success should be explained by variation in performance traits relevant to combat Despite such a straightforward prediction, tests of this hypothesis are conspicuously lacking We show that territorial male collared lizards with greater bite-force capacity sire more offspring than weaker biting rivals but exhibit no survival advantage We did not detect stabilizing or disruptive selection on bite-force capacity Taken together, these results support the hypothesis that superior weapon performance provides a fitness advantage through increased success in male contests Sexual selection on weapon performance therefore appears to be a force driving the evolution and maintenance of sexual dimorphism in head shape © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 840‐845
TL;DR: This study begins to tackle the thorny issue of species delimitation in a complicated group of Neotropical passerine birds in which sets of characters vary substantially across space, but do not obviously vary in a concerted fashion.
Abstract: The acceptance of the generalized or unified concept of species (i.e. that species are segments of population lineages) implies that an important task for systematists is to focus on identifying lineages and on testing hypotheses about the acquisition of properties such as phenotypic diagnosability, reciprocal monophyly, or mechanisms of reproductive isolation. However, delimiting species objectively remains one of the most challenging problems faced by biologists. In the present study, we begin to tackle the thorny issue of species delimitation in a complicated group of Neotropical passerine birds (the Arremon torquatus complex, Emberizidae) in which sets of characters vary substantially across space, but do not obviously vary in a concerted fashion. To earlier discussions of species limits in the group, we add a historical perspective offered by a recent molecular phylogeny, present quantitative analyses of morphological and vocal variation, and incorporate ecological niche models as a new tool that aids species delimitation by highlighting cases of ecological distinctiveness and cases where populations appear to be in independent evolutionary trajectories, despite being connected by environments unlikely to represent barriers to gene flow. We demonstrate that at least one pair of taxa (and likely another) currently treated as conspecific are, in fact, distinct lineages that merit species status under essentially any species criterion. However, other pairwise comparisons are not as straightforward owing to nonconcordant patterns of variation in different traits and to the impossibility of distinguishing which characters are causes and which are consequences of reproductive (and evolutionary) isolation. After considering several alternatives, we propose a provisional classification of the complex recognizing eight tentative species-level taxa. Although this classification is likely to change as more detailed work is conducted, it provides a better foundation for studying the biology of these birds and helps to better describe their diversity, which is obscured when all taxa are subsumed into a single species name. The present study highlights several outstanding challenges, both practical and conceptual, for future studies. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 152–176.
TL;DR: Analysis of mitochondrial and nuclear DNA sequences and morphological characters from exotic Great Lakes as well as introduced and native Eurasian populations of Proterorhinus marmoratus (Pallas) sensu lato shows marked genetic and Morphological divergence that indicates species-level separation between fresh water and marine/brackish lineages.
Abstract: Cryptic taxa present unique difficulties in the description of biological diversity, which DNA sequencing approaches often readily resolve. The tubenose goby Proterorhinus, along with other Ponto-Caspian fauna, has undergone recent Eurasian range expansion, as well as colonized the North American Great Lakes in 1990. We analysed mitochondrial (cytochrome b and cytochrome c oxidase subunit I) and nuclear (recombination activating gene 1; RAG1) DNA sequences and morphological characters from exotic Great Lakes as well as introduced and native Eurasian populations of Proterorhinus marmoratus (Pallas) sensu lato to assess their species identity and biogeographic patterns. The results obtained show marked genetic and morphological divergence that indicates species-level separation between fresh water and marine/brackish lineages, dating back approximately 3.82–4.30 million years. In addition, freshwater lineages within the Black and Caspian Sea basins show significant genetic and morphological differentiation, corresponding to an estimated 0.92–1.03 million years. We describe new evidence to support at least three separate species: the original P. marmoratus in marine and estuarine habitats within the Black Sea, a freshwater species in the Black Sea basin that was introduced to the North American Great Lakes, and another freshwater species inhabiting the Caspian Sea/Volga River basin. The freshwater tubenose goby in the Black Sea basin originally was described as Proterorhinus semilunaris (Heckel), and this is confirmed to be a valid taxon. The Caspian basin taxon may correspond with Proterorhinus semipellucidus (Kessler), a putative freshwater species in the Caspian basin that was originally described from a single specimen. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 664–684. ADDITIONAL KEYWORDS: Black Sea – Caspian Sea – cytochrome b – COI – exotic species – phylogeography – Ponto-Caspian – RAG1 – systematics.
TL;DR: The idea that feather growth rate and feather quality are traded against each other in blackcaps is supported, apparently caused by different selection associated to migratory and sedentary life styles, which opens new insights into the diversification of moult patterns in birds.
Abstract: Migratory birds have less time for moulting than sedentary birds, which may force them to produce their feathers faster at the expense of reducing feather quality. However, the effects of migration on the trade-off between moult speed and plumage quality remain to be studied in natural populations. We analysed the relationship between growth rate and quality of individual feathers, taking advantage of natural variation between migratory and sedentary populations of blackcaps Sylvia atricapilla. As predicted by life-history theory, individual blackcaps showed variable individual quality, which was revealed by positive correlations between feather growth rate and feather mass within populations. However, migrants grew up their feathers faster, producing lighter feathers than sedentary blackcaps. These results support the idea that feather growth rate and feather quality are traded against each other in blackcaps. Such a trade-off is apparently caused by different selection associated to migratory and sedentary life styles, which opens new insights into the diversification of moult patterns in birds.
TL;DR: It is emphasized that, when employed with caveats, major palaeoenvironmental events could represent very powerful tools for the calibration of the dating of divergences using molecular data.
Abstract: The influence of Quarternary glacial cycles on the extant diversity of Holarctic species has been intensively studied. It has been hypothesized that palaeoclimatic changes are responsible for divergence events in lineages. A constant improvement in DNA sequencing and modeling methods, as well as palaeoclimatic reconstruction, permit a deeper exploration of general causes of speciation in geological time. In the present study, we sampled, as exhaustively as possible, the butterflies belonging to the genus Melitaea (Lepidoptera: Nymphalidae), which are widely spread in the Palaearctic region. We conducted analyses to assess the phylogeny of the genus and estimated the timing of divergence and the most likely distribution of ancestral populations. The results obtained indicate that the systematics of the genus is in need of revision and that the diversity of the genus has been profoundly shaped by palaeoenvironmental changes during its evolutionary history. The present study also emphasizes that, when employed with caveats, major palaeoenvironmental events could represent very powerful tools for the calibration of the dating of divergences using molecular data.
TL;DR: The present study documents for the first time embryo development in the order Verongida, which is a shared trait that has encouraged placement of these orders together within Demospongiae, although their relationships remain uncer-tain.
Abstract: Approximately 85% of extant sponges (phylum Porifera) belong to the class Demospongiae, which contains 14taxonomic orders. In the orders Verongida, Dictyoceratida, and Dendroceratida, jointly referred to as ‘keratosedemosponges’, the skeleton does not contain siliceous spicules but only spongin fibres. This shared trait hasencouraged placement of these orders together within Demospongiae, although their relationships remain uncer-tain. The present study documents for the first time embryo development in the order Verongida (
TL;DR: This shell character may have broad ecological significance and could have considerable utility to palaeontologists, taxonomists, and conservation biologists, and could be a result of higher temperatures and phytoplankton densities in marinas.
Abstract: Most species of freshwater mussels (Unionoida) show a wide variability in shell form and size but an understanding of which factors determine unionoid morphology is poor. We identified ecophenotypic trends in shell and internal characters within three unionoid species from two habitat types (marinas and river) of the River Thames, UK, using traditional and modern morphometric techniques. In marinas, all species grew to larger maximum sizes than in the river, which might be a result of higher temperatures and phytoplankton densities in marinas. Unio pictorum in marinas was more elongated than in the river and Fourier shape analysis revealed a trend from dorsally arched river specimens to straight dorsal and pointed posterior margins in marina individuals. The degree of shell elongation and shape of dorso-posterior margin were not associated with sediment composition, but were associated with the different hydrological characters of the two habitat types. Relative shell width was a poor indicator of collection site and influenced by allometric growth. Unlike U. pictorum, a difference in shell elongation of marina and river mussels could not be detected in Unio tumidus and Anodonta anatina. However, all three species showed the same trends regarding the shape of the dorso-posterior shell margin. This shell character may thus have broad ecological significance and could have considerable utility to palaeontologists, taxonomists, and conservation biologists. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 814‐825. ADDITIONAL KEYWORDS: fourier shape analysis ‐ intraspecific variability ‐ palaeontological reconstruction ‐ Unionidae.
TL;DR: The present study shows that monogamous pair-living is restricted to one monophyletic group of shrimps and therefore probably evolved only once, and indicates that the genus Lysmata is paraphyletic and includes the genus Exhippolysmata.
Abstract: Shrimps from the genus Lysmata are known because of their wide diversity of lifestyles, mating systems, symbiotic partnerships, and conspicuous coloration. They can occur in crowds (large aggregations), in small groups, or as socially monogamous pairs. Shrimps from this genus are rare, if not unique among crustaceans, because of their unusual sexual system. To date, the sexual system of all species investigated comprises a protandric simultaneous hermaphroditism: shrimps initially mature and reproduce as males and later in life turn into functional simultaneous hermaphrodites. The evolutionary relationships of the species within the genus are unsettled. A molecular phylogeny of the group may shed light on the evolutionary origins of the peculiar sexual and social systems of these shrimps and help resolve standing taxonomic questions long overdue. Using a 647-bp alignment of the 16S rRNA mitochondrial DNA, we examined the phylogenetic relationship of 21 species of shrimps from the genus Lysmata from several biogeographical regions; the Atlantic, Pacific, and Indo-Pacific. The resulting phylogeny indicates that the genus is paraphyletic and includes the genus Exhippolysmata. The constituent species are subdivided into three well supported clades: one group exclusively composed of neotropical species; a second clade comprising the Indo-Pacific and Atlantic symbiotic fish cleaner shrimps; and a third clade including tropical and temperate species from the Atlantic and Pacific. The molecular phylogeny presented here does not support a historical contingency hypothesis, previously proposed to explain the origins of protandric simultaneous hermaphroditism within the genus. Furthermore, the present study shows that monogamous pair-living is restricted to one monophyletic group of shrimps and therefore probably evolved only once. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 415–424.
TL;DR: This study highlights the importance of ecological heterogeneity over small geographical scales for evolutionary diversification during the early stages of adaptive radiation, and lays the foundation for future research on this ecologically diverse, postglacial system of threespine stickleback in Cook Inlet, Alaska.
Abstract: Adaptive radiations are a major source of evolutionary diversity in nature, and understanding how they originate and how organisms diversify during the early stages of adaptive radiation is a major problem in evolutionary biology. The relationship between habitat type and body shape variation was investigated in a postglacial radiation of threespine stickleback in the upper Fish Creek drainage of Cook Inlet, Alaska. Although small, the upper Fish Creek drainage includes ecologically diverse lakes and streams in close proximity to one another that harbour abundant stickleback. Specimens from ancestral anadromous and derived resident freshwater populations differed substantially and could be distinguished by body shape alone, suggesting that the initial stages of adaptation contribute disproportionately to evolutionary divergence. Body shape divergence among resident freshwater populations was also considerable, and phenotypic distances among samples from freshwater populations were associated with habitat type but not geographical distance. As expected, stream stickleback from slow-moving, structurally complex environments tended to have the deepest bodies, stickleback from lakes with a mostly benthic habitat were similar but less extreme, and stickleback from lakes with a mostly limnetic habitat were the most shallow-bodied, elongate fish. Beyond adapting rapidly to conditions in freshwater environments, stickleback can diversify rapidly over small geographical scales in freshwater systems despite opportunities for gene flow. This study highlights the importance of ecological heterogeneity over small geographical scales for evolutionary diversification during the early stages of adaptive radiation, and lays the foundation for future research on this ecologically diverse, postglacial system. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 139‐151.
TL;DR: The results show that environmental conditions are probably important for the distribution of the genus Cephalidiosus, in conjunction with other factors such as resource (host plant) distribution, but suggest that the same environmental conditions have not influenced the speciation processes and diversification in the genus.
Abstract: The patterns of local endemism in New Caledonia were analysed in two endemic genera of Tingidae (Insecta, Heteroptera), Cephalidiosus and Nobarnus, through a phylogenetic analysis and species' distribution modelling. The aim was to determine the possible causes of diversification and endemism in New Caledonia. Our results show that environmental conditions are probably important for the distribution of the genus Cephalidiosus, in conjunction with other factors such as resource (host plant) distribution, but suggest that the same environmental conditions have not influenced the speciation processes and diversification in the genus. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 177–184.
TL;DR: The extent of variation of life-history traits among sympatric populations of the pea aphid Acyrthosiphon pisum, which shows several host races that are specialised on various plants of the family Fabaceae plants and is an established model for ecological speciation, is investigated.
Abstract: Variation in traits affecting preference for, and performance on, new habitats is a key factor in the initiation of ecological specialisation and adaptive speciation. However, habitat and resource use also involves other traits whose influence on ecological and genetic divergence remains poorly understood. In the present study, we investigated the extent of variation of life-history traits among sympatric populations of the pea aphid Acyrthosiphon pisum, which shows several host races that are specialised on various plants of the family Fabaceae plants and is an established model for ecological speciation. First, we assessed the community structure of microbial partners within host populations of the pea aphid. The effect of these microbes on host fitness is uncertain, although there is growing evidence that they may modulate various important adaptive traits of their host such as plant utilisation and resistance against natural enemies. Second, we performed a multivariate analysis on several ecologically relevant features of host populations recorded in the present and previous studies (including microbial composition, colour morph, reproductive mode, and male dispersal phenotype), enabling the identification of correlations between phenotypic traits. We discuss the ecological significance of these associations of traits in relation to the habitat characteristics of pea aphid populations, and their consequences for the evolution of ecological specialisation and sympatric speciation
TL;DR: It is demonstrated that macropters are of high significance for the range expansion of wing-dimorphic insects because a single-year climatic anomaly can induce strong dispersal processes.
Abstract: During recent decades, many species have responded to global warming by poleward range expansions. We require a better mechanistic understanding of the nature and extent of such processes to assess how climate change might affect biodiversity. Wing-dimorphic bush-crickets are excellent objects to study dispersal and colonization processes at the range margin because the long-winged morphs (macropters) represent dispersal units of otherwise flightless species. Moreover, these insects produce noisy songs and can easily be mapped. The present study comprised a detailed investigation of the population dynamics and genetics at the edge of the range of Roesel’s bush-cricket, Metrioptera roeselii. We mapped the distribution of this insect in a previously unoccupied area of 185 km 2 and examined the genetic structure at the range margin using four polymorphic microsatellite loci. The results obtained demonstrate that the European heat wave in 2003 induced a strong immigration of macropters in the area stemming from multiple sources, whereas only few immigrants were recorded in the two subsequent years. Macropters were genotyped in a distance of up to 19.1 km from their origin, considerably exceeding the known dispersal distances for this species. Moreover, the data show that strong local founder effects are equalized on a large scale by the high number of immigrants from multiple sources. The present study demonstrates that macropters are of high significance for the range expansion of wing-dimorphic insects because a single-year climatic anomaly can induce strong dispersal processes. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 118‐127.
TL;DR: The results imply that the narrow continental shelf coupled with sea level changes had a strong influence on the obligate freshwater fishes in Chile, suggesting that faunal breaks have only limited utility in explaining phylogeographic patterns.
Abstract: We examined the role of several earth history events on the phylogeographic distribution of the catfish Tricho- mycterus areolatus in Chile using the cytochrome b gene. We explored three biogeographic hypotheses: that sea level changes have resulted in the isolation of populations by drainages; that glaciation has impacted genetic diversity; and that ichthyological subprovince boundaries correspond to phylogeographic breaks in our focal species. We found seven well-supported clades within T. areolatus with high levels of genetic divergence. The strongest signal in our data was for an important role of sea level changes structuring populations. Five of the seven clades mapped cleanly to the geographic landscape and breaks corresponded closely to areas of narrowest continental shelf. In addition, few haplotypes were shared between rivers within clades, suggesting that only limited local movement of individuals has occurred. There was no relationship between the levels of genetic diversity and the proportion of individual drainages covered by glaciers during the last glacial maximum. Two phylogeographic breaks within T. areolatus did match the two previously identified faunal boundaries, but we found three additional breaks, which suggests that faunal breaks have only limited utility in explaining phylogeographic patterns. These results imply that the narrow continental shelf coupled with sea level changes had a strong influence on the obligate freshwater fishes in Chile. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 876-892.
TL;DR: Genealogical exclusivity at both mtDNA and nuclear DNA among the geographically coherent groups coupled with pronounced sequence divergence suggested a two-fold increase in the number of species within Peripatopsis.
Abstract: The endemic South African velvet worm genus Peripatopsis currently contains eight recognized species described from variable morphological characters and the current taxonomy is unsatisfactory. In an attempt to investigate evolutionary relationships within Peripatopsis, we collected 137 individuals from 34 sample localities for six of the eight species. Sequence data derived from two partial mitochondrial (mt)DNA gene loci (COI and 12S rRNA), as well as partial sequence data from the ribosomal nuclear 18S rDNA locus in combination with gross morphological characters and scanning electron microscopy (SEM), was used to examine evolutionary relationships. Phylogenetic relationships were investigated using minimum evolution (ME) and Bayesian inferences (BI). Additionally, we also undertook a maximum likelihood (ML) analyses on the combined DNA sequence data set. The combined DNA evidence topologies derived from the ME, BI, and ML was highly congruent and was characterized by the presence of multiple lineages within recognized taxa. Peripatopsis clavigera, Peripatopsis moseleyi, and Peripatopsis sedgwicki each comprised two evolutionary lineages; Peripatopsis capensis comprised three; and Peripatopsis balfouri comprised six operational taxonomic units respectively. Genealogical exclusivity at both mtDNA and nuclear DNA among the geographically coherent groups coupled with pronounced sequence divergence suggested a two-fold increase in the number of species within Peripatopsis. Previously used gross morphological characters (such as the number of leg pairs and colour) were either highly variable within operational taxonomic units, or were invariant, suggesting that alternative morphological characters are necessary for species discrimination. SEM results revealed potentially useful diagnostic characters that can discriminate between at least discriminate some of the newly-identified lineages. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society 2009, 97, 200–216.
TL;DR: The presence of multiple unique haplotypes among SFPW from South Japan, together with previously documented morphological and ecological differences, suggests that the southern form represents a distinct subspecies and/or evolutionary significant unit.
Abstract: Pilot whales (Globicephala spp.) provide an interesting example of recently diverged oceanic species with a complex evolutionary history. The two species have wide but largely non-overlapping ranges. Globicephala melas (long-finned pilot whale; LFPW) has an antitropical distribution and is found in the cold-temperate waters of the North Atlantic and Southern Hemisphere, whereas Globicephala macrorhynchus (short-finned pilot whale; SFPW) has a circumglobal distribution and is found mainly in the tropics and subtropics. To investigate pilot whale evolution and biogeography, we analysed worldwide population structure using mitochondrial DNA (mtDNA) control region sequences (up to 620 bp) from a variety of sources (LFPW = 643; SFPW = 150), including strandings in New Zealand and Tasmania, and whale-meat products purchased on the markets of Japan and Korea. Phylogenetic reconstructions failed to support a reciprocal monophyly of the two species, despite six diagnostic substitutions, possibly because of incomplete lineage sorting or inadequate phylogenetic information. Both species had low haplotype and nucleotide diversity compared to other abundant widespread cetaceans (LFPW, π = 0.35%; SFPW, π = 0.87%) but showed strong mtDNA differentiation between oceanic basins. Strong levels of structuring were also found at the regional level. In LFPW, phylogeographic patterns were suggestive either of a recent demographic expansion or selective sweep acting on the mtDNA. For SFPW, the waters around Japan appear to represent a centre of diversity, with two genetically-distinct forms, as well as a third population of unknown origin. The presence of multiple unique haplotypes among SFPW from South Japan, together with previously documented morphological and ecological differences, suggests that the southern form represents a distinct subspecies and/or evolutionary significant unit. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 729–744.