Showing papers in "Biological Journal of The Linnean Society in 2006"
TL;DR: The evolutionary lability of sex-determining modes in fishes contrasts strikingly with the evolutionary conservatism of sex determination within both mammals and birds.
Abstract: We compiled information from the literature on the taxonomic distributions in extant teleost fishes of alternative sex-determination systems: male-heterogametic (XY) gonochorism, female-heterogametic (ZW) gonochorism, hermaphroditism, unisexuality, and environmental dependency. Then, using recently published molecular phylogenies based on whole-genomic or partial mitochondrial DNA sequences, we inferred the histories and evolutionary transitions between these reproductive modes by employing maximum parsimony and maximum likelihood methods of phylogenetic character mapping. Across a broad teleost phylogeny involving 25 taxonomic orders, a highly patchy distribution of different sex-determination mechanisms was uncovered, implying numerous transitions between alternative modes, but this heterogeneity also precluded definitive statements about ancestral states for most clades. Closer inspection of family-level and genus-level phylogenies within each of four orders further bolstered the conclusion that shifts in sex-determining modes are evolutionarily frequent and involve a variety of distinct ancestral-descendant pathways. For possible reasons discussed herein, the evolutionary lability of sex-determining modes in fishes contrasts strikingly with the evolutionary conservatism of sex determination within both mammals and birds. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 83–93.
217 citations
TL;DR: Overall, the rDNA molecular phylogeny has remained stable following the incorporation of the additional taxa, with these additions having little impact on the major evolutionary patterns in the tree.
Abstract: We have incorporated an additional 56 species of land snails and slugs in our ribosomal (r) RNA molecular phylogeny The new taxa include representatives of several important groups The molecular tree now includes 160 species of stylommatophoran land snails and slugs in 144 genera in 61 families In the rDNA tree, the Stylommatophora are principally divided into an ‘achatinoid’ and a ‘non-achatinoid’ clade Within these clades, several major land snail groups, including the Orthurethra, Elasmognatha, Limacoidea, and Helicoidea, are supported Overall, the rDNA molecular phylogeny has remained stable following the incorporation of the additional taxa, with these additions having little impact on the major evolutionary patterns in the tree Taxonomic coverage of the Orthurethra, Orthalicidae, Camaenidae, and Bradybaenidae is increased significantly The camaenids and bradybaenids form a complex, and both appear to be paraphyletic Several families of uncertain affinity, such as the Sagdidae and Thyrophorellidae, are included for the first time The Sagdidae are shown to belong to the Helicoidea, and the Thyrophorellidae to the Achatinoidea © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 593–610
173 citations
TL;DR: D dwarf chameleons showed different behavioural responses, including colour change, towards multiple predators that detect and capture prey in different ways, and whether these antipredator responses varied geographically was consistent among populations.
Abstract: Potential prey are often exposed to multiple predators that vary in their foraging tactics and ability to detect prey. For animals that rely on crypsis to avoid predators, one solution is to alter their behaviour or appearance to maximize crypsis in ways that are specific to different types of predator. We tested whether dwarf chameleons (Bradypodion transvaalense) showed different behavioural responses, including colour change, towards multiple predators (bird and snake models) that detect and capture prey in different ways, and whether these antipredator responses varied geographically. Chameleons consistently used the same body postures (lateral compression and flipping to the opposite side of the branch) and displayed similar chromatic (colour) contrast against the natural background in response to both predator types. However, they became significantly more achromatically contrasting (brighter) in the presence of the snake compared to the bird. This relative difference in achromatic contrast towards the two types of predator was consistent among populations. There were also significant differences in both absolute achromatic and chromatic contrast among populations despite very similar light environment, background coloration and habitat structure. Our results highlight facultative crypsis as one type of flexible antipredator tactic and emphasize the importance of visual ecology in understanding prey–predator interactions. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 437–446.
143 citations
TL;DR: The relationship between beak morphology and song features within a bimodal population of Geospiza fortis on Santa Cruz Island, Galapagos is characterized and it is suggested that differences in song between the two modes of the distribution may influence mate recognition and perhaps facilitate assortative mating by beak size and population divergence.
Abstract: Animal mating signals evolve in part through indirect natural selection on anatomical traits that influence signal expression. In songbirds, for example, natural selection on beak form and function can influence the evolution of song features, because of the role of the beak in song production. In this study we characterize the relationship between beak morphology and song features within a bimodal population of Geospiza fortis on Santa Cruz Island, Galapagos. This is the only extant population of Darwin’s finches that is known to possess a bimodal distribution in beak size. We test the hypothesis that birds with larger beaks are constrained to produce songs with lower frequencies and decreased vocal performance. We find that birds with longer, deeper, and wider beaks produce songs with significantly lower minimum frequencies, maximum frequencies and frequency bandwidths. Results from the analysis of the relationship between beak morphology and trill rate are mixed. Measures of beak morphology correlated positively with ‘vocal deviation’, a composite index of vocal performance. Overall these results support a resonance model of vocal tract function, and suggest that beak morphology, a primary target of ecological selection in Darwin’s finches, affects the evolution of mating signals. We suggest that differences in song between the two modes of the distribution may influence mate recognition and perhaps facilitate assortative mating by beak size and population divergence. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 489–498.
142 citations
TL;DR: The diversity and phylogenetic position of photobionts in the widespread saxicolous, crustose lichen-forming asco- mycete Lecanora rupicola s.l. is presented.
Abstract: The diversity and phylogenetic position of photobionts in the widespread saxicolous, crustose lichen-forming asco- mycete Lecanora rupicola s.l. is presented. The algal partners of this lichen species complex belong to diverse and unrelated lineages in the genus Trebouxia . Specimens were sampled from different habitats and geographical ori- gins. Either whole thallus DNA extractions or minute fragments of the algal layer of the lichen thallus were sub- jected to polymerase chain reaction, using primers that specifically amplify internal transcribed spacer rDNA of the photobionts. No correlations between different chemical races of L. rupicola with particular lineages of Trebouxia spp. were found. Irrespective of the different algal partners, all lichen thalli abundantly developed ascomata. L. rupicola apparently maintains full fecundity with a low degree of selectivity for photobionts, which promotes the occurrence of this lichen-forming species in ample ecological situations. © 2006 The Linnean Society of London, Bio- logical Journal of the Linnean Society , 2006, 88 , 283-293. ADDITIONAL KEYWORDS: Lecanora rupicola - lichens - phylogeny - selectivity - symbiosis - Trebouxio- phyceae - Trebouxia .
132 citations
TL;DR: Long-term climatic stability, combined with topoclimatic and edaphic diversity and regular fire occurrence, is likely to be responsible for the remarkable geophyte diversity of the Cape, as compared to other mediterranean-climate regions.
Abstract: The Cape Region (here treated as the winter rainfall region of southern Africa, thus including fynbos, renosterveld and succulent karoo vegetation) is the world's foremost centre of geophyte diversity. Some 2100 species in 20 families have been recorded from this area, 84% of them endemic. The most important families, with more than a hundred geophyte species each, are Iridaceae, Oxalidaceae, Hyacinthaceae, Orchidaceae, Amaryllidaceae and Asphodelaceae. Although southern Africa does not appear to have been the main diversification centre for the plant orders with highest geophyte representation (Asparagales and Liliales), it represents an active centre of transition to geophytism, such transitions having occurred independently in numerous plant groups, often followed by rapid speciation. Several Cape geophyte groups have consequently expanded across Africa to the Mediterranean Basin, and possibly to other winter rainfall regions. Remarkably high local species diversity in renosterveld vegetation, even in relatively homogeneous environments, suggests that pollinator specificity and phenology play an important role in niche partitioning. However, character diversity is also high in storage organs and leaves, and this could account for the high species diversity values recorded at larger spatial scales, especially across environmental gradients. Long-term climatic stability, combined with topoclimatic and edaphic diversity and regular fire occurrence, is likely to be responsible for the remarkable geophyte diversity of the Cape, as compared to other mediterranean-climate regions. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 27–43.
119 citations
TL;DR: The data suggest that body size affects the dietary ecology of animals through its effect on head size and bite force and changes in head morphology independent of changes in overall size also have important effects on performance and diet.
Abstract: It has been documented extensively that body size affects the physiology and musculoskeletal function of organisms. However, less well understood is how body size affects the ecology of organisms through its effects on physiology and performance. We explored the effects of body size on morphology and performance in different ontogenetic classes and sexes of a common Anolis lizard (A. lineatopus). Next, we tested whether these morphological and performance differences may affect functional aspects of the diet such as prey size and prey hardness. Our data showed that males, females and juveniles differ significantly in head size, head shape and bite force. Multiple regression models indicated that head shape and bite force are significantly correlated to prey size and hardness. Yet juveniles had relatively large heads and bit disproportionately hard for their size, allowing them to eat prey as large as those of females. However, for a given prey size, males and females ate more robust prey than did juveniles. Additionally, males ate relatively harder prey than did juveniles. These data suggest that: (1) body size affects the dietary ecology of animals through its effect on head size and bite force; (2) changes in head morphology independent of changes in overall size also have important effects on performance and diet. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 443–454.
118 citations
TL;DR: The genetic relationships between taxa with intermediate levels of divergence were well defined by allozyme data, but showed short internodes and low bootstrap values for mitochondrial data, suggesting a rapid radiation of their lineages during the Messinian Lago Mare phase.
Abstract: Allozymes and sequencing of mitochondrial cytochrome b (cyt b) and 12S genes were used to reconstruct the genetic structure and phylogenetic relationships of all Discoglossus taxa described so far (except the probably extinct D. nigriventer). This is the first time that a comprehensive study on the Discoglossus painted frogs has used nuclear and mitochondrial markers, evidencing a discordant pattern between the two datasets. Comparison of these discrepancies suggests a role of stochastic sorting of ancestral polymorphisms, possibly associated with male-biased dispersal and present or past secondary contact. The genetic relationships between taxa with intermediate levels of divergence were well defined by allozyme data, but showed short internodes and low bootstrap values for mitochondrial data, suggesting a rapid radiation of their lineages during the Messinian Lago Mare phase. The results provide information about the taxonomic status of D. galganoi and D. jeanneae, considered as subspecies, and indicate D. pictus as nonmonophyletic, confirming D. scovazzi as a distinct species. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 515–536.
106 citations
TL;DR: Differences in echolocation call frequency among populations did not reflect phylogenetic relationships, indicating that call frequency is a poor indicator of evolutionary history, and it is proposed that the name Hipposideros khasiana is proposed for bats of the 85-kHz phonic type.
Abstract: The intermediate leaf-nosed bat (Hipposideros larvatus) is a medium-sized bat distributed throughout the Indo-Malay region. In north-east India, bats identified as H. larvatus captured at a single cave emitted echolocation calls with a bimodal distribution of peak frequencies, around either 85 kHz or 98 kHz. Individuals echolocating at 85 kHz had larger ears and longer forearms than those echolocating at 98 kHz, although no differences were detected in either wing morphology or diet, suggesting limited resource partitioning. A comparison of mitochondrial control region haplotypes of the two phonic types with individuals sampled from across the Indo-Malay range supports the hypothesis that, in India, two cryptic species are present. The Indian 98-kHz phonic bats formed a monophyletic clade with bats from all other regional populations sampled, to the exclusion of the Indian 85-kHz bats. In India, the two forms showed 12–13% sequence divergence and we propose that the name Hipposideros khasiana for bats of the 85-kHz phonic type. Bats of the 98-kHz phonic type formed a monophyletic group with bats from Myanmar, and corresponded to Hipposideros grandis, which is suggested to be a species distinct from Hipposideros larvatus. Differences in echolocation call frequency among populations did not reflect phylogenetic relationships, indicating that call frequency is a poor indicator of evolutionary history. Instead, divergence in call frequency probably occurs in allopatry, possibly augmented by character displacement on secondary contact to facilitate intraspecific communication.
104 citations
TL;DR: Sun bears fed on 115 fruit species covering 54 gen- era and 30 families, with Ficus (Moraceae) being the main fallback fruit as discussed by the authors, and the families Moraceae, Burseraceae, and Myrtaceae contributed more than 50% to the sun bear fruit diet.
Abstract: − 1 during the intermast period. Almost 100% of sun bear diet consisted of fruit during mast fruiting period, whereas sun bear diet was predomi- nantly insectivorous during intermast periods. The majority of sun bear fruit trees displayed 'mast-fruiting' and 'supra-annual' fruiting patterns, indicating sporadic productivity. Sun bears fed on 115 fruit species covering 54 gen- era and 30 families, with Ficus (Moraceae) being the main fallback fruit. The families Moraceae, Burseraceae, and Myrtaceae contributed more than 50% to the sun bear fruit diet. Sun bear fruit feeding observations were unevenly distributed over forest types with more observations in high-dry forest type despite fewer fruiting events, possibly due to a side-effect of high insect abundance that causes bears to use these areas more intensively. The possible evo- lutionary pathways of sun bears in relation to the Sundaic environment are discussed. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 489-508. ADDITIONAL KEYWORDS: Borneo - community fruiting - ENSO - fruiting synchrony - lowland dipterocarp forest - mast fruiting - Ursidae.
103 citations
TL;DR: Five of the seven focal species of the present study were paraphyletic for mtDNA genealogies, suggesting that they represent complexes of species, and nested clade phylogeographical analysis (NCPA) analyses suggest that different historical and demographic processes have shaped the observed patterns.
Abstract: In poorly known groups for which data are insufficient to develop biologically plausible model-based approaches to phylogeographical analyses, a ‘first hypotheses’ protocol is suggested as offering the best way to generate hypotheses for subsequent model-based tests. Preliminary hypotheses are formulated about species boundaries and population processes in three species complexes of the Liolaemus boulengeri group in the context of mtDNA ‘congeneric phylogeography’. The temperate South American Liolaemus provides a model with ancient and recent allopatric divergence across ecologically and geologically complex landscapes, incipient speciation, secondary contact, and discordance between molecular and morphological patterns of variation. Moderately dense sampling of widely distributed ‘inertial’ species in the Patagonian Steppe has revealed hidden genetic and probably species diversity, and also hinted at demographic and historical processes that may have shaped the histories of these taxa. Five of the seven focal species of the present study were paraphyletic for mtDNA genealogies, suggesting that they represent complexes of species, and nested clade phylogeographical analysis (NCPA) analyses suggest that different historical and demographic processes have shaped the observed patterns. Introgression and incomplete lineage sorting are hypothesized as being the cause of some of the observed paraphyly. Provisional delimitations of species are proposed and NCPA is used to generate hypotheses of population history, all of which are subject to further testing. Multi-faceted studies, involving phylogenetic assessments of independent molecular markers and morphological variation across codistributed taxa with estimates of niche breadths in a landscape context, will likely yield the most promising returns for cross-validation of hypotheses of population and speciation histories. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 241–275.
TL;DR: It is suggested that some drosophilids migrate to the forests when climatic conditions are too stressful in thesavannas, as species richness in the savanna vegetation clearly decreased in the dry season, increasing again in the wet season.
Abstract: Although natural populations of drosophilid flies have been the subject of ecological studies, the population ecology of these insects in the tropics is still poorly known. This paper discusses aspects of the relationship between drosophilids and their environment, based on 28 monthly collections made in two contrasting vegetations of the Brazilian Cerrado biome: gallery forest and savanna. Exotic species were found in both types of environment; but 14 of the 30 captured Neotropical species occurred exclusively in the gallery forests, probably because of their climatic stability and greater environmental heterogeneity. Even though some endemic species were more abundant in the dry and cold months, most populations exhibited peaks of abundance in the wet season. The species diversity indexes (H′ and D), higher in the dry season, were probably affected by increased evenness at this time of year, when the populations of practically all the species are greatly reduced. As species richness in the savanna vegetation clearly decreased in the dry season, increasing again in the wet season, it is suggested that some drosophilids migrate to the forests when climatic conditions are too stressful in the savannas. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 233–247.
TL;DR: Molecular data, the nucleotide sequences of four protein-coding mitochondrial genes (3806 bp total), are used to provide a well-supported phylogeny for the genus Natrix, in which N. maura is basal with N.-natrix and N-tessellata being sister species and an early Miocene to late Oligocene origin for the three species.
Abstract: Some aspects of the natural history of snakes of the colubrid genus Natrix have been well studied. With their extensive European distribution and relative abundance, their ecology, reproduction and behaviour are well known. Yet other facets of their biology remain poorly understood. These include knowledge of Natrix phylogeny, hypotheses explaining the current distribution of the three extant members of the genus, and their evolution and relationships. In this study we used molecular data, the nucleotide sequences of four protein-coding mitochondrial genes (3806 bp total), to provide a well-supported phylogeny for the genus Natrix. With these molecular data, evidence from the fossil record, and knowledge of palaeogeological events, we used two approaches in designing a time scale which we used to date the major events in Natrix speciation and intraspecific variation. Our data strongly support a phylogeny for the genus in which N. maura is basal with N. natrix and N. tessellata being sister species. The calibrated molecular clock suggests that N. maura diverged from the common ancestor of the three species 18–27 mya and that N. natrix and N. tessellata diverged 13–22 mya. Although the ranges of these estimates are large they support an early Miocene to late Oligocene origin for the three species. Intraspecific divergence is estimated to have commenced 5.3, 6.0 and 6.7 mya with evolutionary rates of 1 : 1.25 : 1.35% per million years for N. maura, N. natrix and N. tessellata, respectively. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 127–143.
TL;DR: The hypothesis that head shape in males is under antagonistic selective pressures, which may partly explain the pattern of head shape dimorphism, is consistent with the notion of sexual selection for high bite force in males.
Abstract: The Common Chuckwalla [Sauromalus ater (= obesus)] is a large, sexually dimorphic lizard with a flattened head that takes refuge from predators in rock crevices. Males use their relatively large heads to bite competing males during territorial fights and to restrain females during copulation. Flattened heads with an antipredator function (i.e. seeking refuge in crevices) and enlarged heads with intrasexual competition and reproductive functions suggest possible antagonism between selective pressures on head morphology in males. To examine this hypothesis, we performed a morphometric analysis and measured the bite-force performance of 49 adult chuckwallas. Males had disproportionately wider heads than females, but did not have deeper heads. Males bit with nearly four times the force of females, consistent with the notion of sexual selection for high bite force in males. Although constrained by crevice-wedging behaviour, head depth was a good predictor of bite force in both sexes. In males, however, osteological head width also was a good predictor of bite force. These results are consistent with the hypothesis that head shape in males is under antagonistic selective pressures, which may partly explain the pattern of head shape dimorphism. The disproportionately wide head of males may reflect anatomical modifications to enhance bite force in response to sexual selection in spite of presumed constraints on head shape for crevice-wedging behaviour © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 215–222.
TL;DR: The genetic differences at large spatial scales counteracted the expected effects of temperature differences in the wild, suggesting countergradient variation in morphology among these populations of Atlantic cod.
Abstract: A common-garden experiment was conducted on larvae to test for genetic differences in body shape among populations of Atlantic cod (Gadus morhua). Offspring from four north-west Atlantic regions were reared from hatching to postmetamorphosis at two temperatures (7 ± 1 °C and 11 ± 1 °C) and two food levels (1500 and 4500 prey L−1). Body shape differed between populations and treatments. Population differences were greatest between south-west Scotian Shelf cod and those further north; the former were characterized by a deeper body, larger head, and longer caudal peduncle than cod from the other populations. Significant differences were also observed between two putative populations on the south-west Scotian Shelf, suggesting genetic divergence between spawning aggregations at small spatial scales ( 1000 km) and small (< 100 km) spatial scales. The genetic differences at large spatial scales counteracted the expected effects of temperature differences in the wild, suggesting countergradient variation in morphology among these populations. © 2006 Her Majesty the Queen in Right of Canada. Journal compilation © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 351–365.
TL;DR: The results show that a specific colour is essential for the birds to recognize the specific aposematic prey; the melanin pattern is not sufficient.
Abstract: Persistent questions concerning the warning coloration of unpalatable insects address whether the bright aposematic colour itself or its combination with a species-specific dark pattern is the key factor in their protection against insectivorous birds, and how chromatic polymorphism originates and is maintained in aposematics In the present study, these questions were tested experimentally, using the birds Parus major, Parus caeruleus, Erithacus rubecula, and Sylvia atricapilla as predators, and chromatically polymorphic firebug Pyrrhocoris apterus: red wild form, white, yellow, and orange mutants (all four of them with the same black melanin pattern, the mutants differing in colour of pteridine pigments only) and the nonaposematic brown-painted wild form as prey The results show that a specific colour is essential for the birds to recognize the specific aposematic prey; the melanin pattern is not sufficient White mutants were no better protected than nonaposematic firebugs; red wild-type and orange mutants were equally well protected against all bird species; and the reaction of birds to yellow mutants was species-specific An evolutionary scenario of ’recurrent recessive mutations’ is formulated to explain the origin of colour polymorphism in some aposematics © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 143–153
TL;DR: The results obtained suggest that carotenoids strengthen parasite resistance at low levels but either benefit parasites or suppress host immunity at high levels, and emphasize the importance of evaluating the effects of diet on multiple aspects of immune system function.
Abstract: Dietary carotenoids have been shown to confer immunological benefits to some species of animals in which males also use these pigments to attract mates. Thus, the potential exists for an allocation trade-off between the sexual and immunological functions of carotenoids. Food availability may also influence immune system function. The present study examined the effects of carotenoid and food availability on the resistance of male guppies (Poecilia reticulata Peters) from four wild populations to the parasite Gyrodactylus turnbulli Harris. Intermediate levels of carotenoid ingestion resulted in the lowest parasite loads, which suggests that carotenoids strengthen parasite resistance at low levels but either benefit parasites or suppress host immunity at high levels. Males raised on the high-food level initially had fewer parasites, suggesting heightened innate immunity relative to males raised on the low-food level. Over the course of the experiment, however, the high-food males supported higher parasite population growth rates than the low-food males. The results obtained emphasize the importance of evaluating the effects of diet on multiple aspects of immune system function, and caution against assuming that positive effects of carotenoids on immunity in one context will automatically translate to other contexts.
TL;DR: This is the first study with a strongly supported phylogenetic framework supporting a transition from viviparity to oviparity, and shows that v Viviparous populations are not monophyletic, and that several evolutionary transitions in parity mode have occurred.
Abstract: The evolution of viviparity in squamates has been the focus of much scientific attention in previous years. In particular, the possibility of the transition from viviparity back to oviparity has been the subject of a vigorous debate. Some studies have suggested this reversal is more frequent than previously thought. However, none of them provide conclusive evidence. We investigated this problem by studying the phylogenetic relationships between oviparous and viviparous lineages of the reproductively bimodal lizard species Zootoca vivipara. Our results show that viviparous populations are not monophyletic, and that several evolutionary transitions in parity mode have occurred. The most parsimonious scenario involves a single origin of viviparity followed by a reversal back to oviparity. This is the first study with a strongly supported phylogenetic framework supporting a transition from viviparity to oviparity. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 1–11.
TL;DR: The definition in the present study displays the huge diversity of the scales (time-scale and population size) involved in actual species, thus explaining away the classical problems raised by previous attempts at defining the species concept.
Abstract: To enrich the Hennigian internodal conception of species, a new formalization of the definition of the species concept is proposed This rigorous definition allows for considerable unification of the various, and sometimes conflicting, techniques of species delimitation used in practice First, the domain of such a definition is set out, namely, the set of all organisms on Earth, past, present, and future Next, the focus is on the genealogical relationship among organisms, which provides the key to analysing the giant or global genealogical network (GGN) connecting all these organisms This leads to the construction of an algorithm revealing the topological structure of the GGN, from families to lineages, ending up with a definition of species as equivalence classes of organisms corresponding to branches of the 'tree of life' Such a theoretical definition of the species concept must be accompanied by various recognition criteria to be operational These criteria are, for example, the ill-named 'biological species concepts', 'phylogenetic species concepts', etc, usually, but wrongly, presented as definitions of the species concept Besides clarifying this disputed point, the definition in the present study displays the huge diversity of the scales (time-scale and population size) involved in actual species, thus explaining away the classical problems raised by previous attempts at defining the species concept (uniparental reproduction, temporal depth of species, and hybridization)
TL;DR: Phylogenetic analysis of newly obtained data from the complete small subunit rDNA (18S) nuclear gene of a wide range of copepods placed the enigmatic Pectenophilus ornatus firmly in the Cyclopoida and revealed an unexpected but strongly supported relationship between the Chondracanthidae and Pseudanthessiidae.
Abstract: Phylogenetic analysis of newly obtained data from the complete small subunit rDNA (18S) nuclear gene of a wide range of copepods placed the enigmatic Pectenophilus ornatus firmly in the Cyclopoida. Both maximum parsimony tree reconstruction, and Bayesian analysis operating under the GTR + I + Γ model of nucleotide substitution, gave identical solutions and placed P. ornatus at the base of the poecilostome families, in apposition to the mytilicolid taxa. The recently suggested assignment to the Siphonostomatoida on the basis of a tubular mouth cone in the pygmy male was rejected not only by the molecular data but also by new morphological observations. Scanning electron microscopy revealed that the appendage previously interpreted as the mandible was in reality the maxilla, the presumptive ‘labium’ only an intermaxillary outgrowth of the ventral cephalic sclerite bearing the widely separated paragnaths, and that there was no basal fusion between the labrum and the ‘posterior lip’ as in genuine siphonostomatoids. Absence of mandibles and their functional replacement by the anteriorly displaced maxillae is a unique and robust apomorphy for the Mytilicolidae and placed unequivocally P. ornatus in that family. The morphology of male Pectenophilus probably evolved as a result of global progenesis, involving early sexual maturation at the metanauplius stage and the complete cessation of somite and limb development. The molecular data were also employed to examine the relationships of two other highly modified parasitic families, the Xarifiidae (inhabiting hard corals) and the Chondracanthidae (parasitic on marine demersal fishes). Our analyses rejected the previously proposed relationship between Xarifiidae and Vahiniidae and strongly supported an Anchimolgidae + (Rhynchomolgidae + Xarifiidae) clade as sister group to the Sabelliphilidae within a monophyletic Lichomolgoidea. The obtained topology suggests that the common ancestor of this clade had already established a symbiotic relationship with scleractinian corals and that host switching occurred only secondarily in the Rhynchomolgidae, involving predominantly other cnidarian and occasionally noncnidarian hosts. Reassessment of the morphology of Parangium provided new evidence for a relationship with the xarifiids, rendering its current position in the Serpulidicolidae extremely unlikely. Both parsimony and Bayesian analyses revealed an unexpected but strongly supported relationship between the Chondracanthidae and Pseudanthessiidae. This result contrasts with earlier views advocating affinity to the Synapticolidae or Lichomolgidae, but was congruent with the previously unnoticed morphological similarity in antennary armature patterns in the first copepodid stage. The morphological grounds used to establish the Lernaeosoleidae were shown to be secondarily derived characters shared with one or several chondracanthid genera. Particularly the similarity between the Lernaeosoleidae and Markevitchielinus demonstrated that the former evolved from a mesoparasitic ancestor within the Chondracanthidae and consequently should sink as a synonym of the latter. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 403–425.
TL;DR: A case is illustrated in which lineage splitting during the speciation process took place without divergence in reproductive isolation mechanisms (e.g. advertisement call in frogs), contrary to expectations predicted using a biological species framework.
Abstract: Leptodactylus fuscus is a neotropical frog ranging from Panama to Argentina, to the east of the Andes mountains, and also inhabiting Margarita, Trinidad, and the Tobago islands. We performed phylogenetic analyses of 12S rRNA, 16S rRNA, tRNA-Leu, and ND1 mitochondrial (mt) DNA sequences from specimens collected across the geographic distribution of L. fuscus to examine two alternative hypotheses: (i) L. fuscus is a single, widely distributed species, or (ii) L. fuscus is a species complex. We tested statistically for geographic association and partitioning of genetic variation among mtDNA clades. The mtDNA data supported the hypothesis of several cryptic species within L. fuscus. Unlinked mtDNA and nuclear markers supported independently the distinctness of a ‘northern’ phylogenetic unit. In addition, the mtDNA data divided the southern populations into two clades that showed no sister relationship to each other, consistent with high differentiation and lack of gene flow among southern populations as suggested by allozyme data. Concordance between mtDNA and allozyme patterns suggests that cryptic speciation has occurred in L. fuscus without morphological or call differentiation. This study illustrates a case in which lineage splitting during the speciation process took place without divergence in reproductive isolation mechanisms (e.g. advertisement call in frogs), contrary to expectations predicted using a biological species framework. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 325‐341. No claim to original US government works.
TL;DR: Molecular phylogenetic analyses of 26 of the 28 species of Ourisia, including eight of ten subspecies and two purported natural hybrids, are presented and used to examine the biogeography of the genus, which is distributed in subalpine to alpine habitats of South America, New Zealand and Tasmania.
Abstract: Molecular phylogenetic analyses of 26 of the 28 species of Ourisia, including eight of ten subspecies and two purported natural hybrids, are presented and used to examine the biogeography of the genus, which is distributed in subalpine to alpine habitats of South America, New Zealand and Tasmania. Gondwanan vicariance, often cited as the cause of this classic austral biogeographical pattern, was rejected by parametric bootstrapping of our combined dataset. Alternatively, various lines of evidence are presented in favour of a South American origin of Ourisia and subsequent dispersal to Australasia. Specifically, the genus likely arose in the Andes of central Chile and spread to southern Chile and Argentina, to the north-central Andes, and finally to Tasmania and New Zealand. The ancestor of the New Zealand species probably first arrived on the South Island, where the New Zealand species of Ourisia are most diverse, and migrated to the North and Stewart Islands. Because the Tasmanian and New Zealand species are sister to one another, the direction of dispersal between these two areas is equivocal. These results agree with other molecular phylogenetic studies that show that past dispersal between southern hemisphere continents has played an important role in the evolutionary history of many high-elevation austral plants. Our data also show that within South America, many of the geographical barriers (with the exception of the Atacama Desert) that have played a role in the evolution of other plant groups have not affected Ourisia species. Within New Zealand, the phylogeny and biogeography of species of Ourisia coincide with the geological history of the country and patterns of other alpine plants. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 479–513.
TL;DR: The topology of the phylogenetic hypothesis, combined with the levels of genetic divergence relative to morphological diversity, demonstrate that the Hydrophis lineage represents a rapidly diverged adaptive radiation.
Abstract: Evolutionary relationships within and between the marine hydrophiine sea snake groups have been inferred primarily using morphological characters, and two major groups traditionally are recognized. The Aipysurus group comprises nine species in two genera, and the taxonomically chaotic Hydrophis group comprises as many as 40 species, of which 27 are generally allocated to the genus Hydrophis and 13 to ten additional genera. In addition to these two major groups are three putatively 'primitive' monotypic genera, Hydrelaps darwiniensis, Ephalophis greyi and Parahydrophis mertoni. The present study investigated the evolutionary relationships of 23 representative species of marine hydrophiines, comprising 15 species from the Hydrophis group, six species from the Aipysurus group, and H. darwiniensis and P. mertoni, to address two broad aims. First, the aim was to provide a robust phylogeny for sea snakes to test previous phylogenetic hypotheses based on morphology, and thus provide some taxonomic stability to the group. Second, there was interest in evaluating the hypothesis that the Hydrophis group might represent a rapidly diverged adaptive radiation. A large mitochondrial DNA data set based on the cytochrome b gene (1080 bp, 401 parsimony informative) and the 16S rRNA gene (510 bp, 57 parsimony informative) was assembled and these data were analysed using parsimony, maximum-likelihood and Bayesian approaches. All analyses yielded virtually the same optimal tree, confirming that hydrophiine sea snakes comprise at least three lineages. The Aipysurus group formed a strongly supported and well-resolved monophyletic clade. The Hydrophis group also formed a strongly supported clade; however, resolution among the genera and species was very poor. Hydrelaps darwiniensis and P. mertoni formed a sister clade to the Hydrophis lineage. Our phylogeny was used to test the validity of previous taxonomic and phylogenetic hypotheses, and to demonstrate that the genus Hydrophis is not monophyletic. Genetic diversity relative to phenotypic diversity is four to seven times greater in the Hydrophis lineage compared with the Aipysurus lineage. The topology of our phylogenetic hypothesis, combined with the levels of genetic divergence relative to morphological diversity, demonstrate that the Hydrophis lineage represents a rapidly diverged adaptive radiation. The data are consistent with the hypothesis that this adaptive radiation may be due to historical sea level fluctuations that have isolated populations and promoted speciation.
TL;DR: It is suggested that mantises have an innate aversion to attacking ants and that this aversion is generalized to myrmecomorphic salticids even in the absence of prior experience with ants.
Abstract: Field data suggest that ants may be important predators of mantises which, in turn, may be important predators of jumping spiders (Salticidae). Using a tropical fauna from the Philippines as a case study, the reactions of mantises to ants, myrmecomorphic salticids (i.e. jumping spiders that resemble ants) and ordinary salticids (i.e. jumping spiders that do not resemble ants) were investigated in the laboratory. Three mantis species (Loxomantis sp., Orthodera sp., and Statilia sp.) were tested with ten ant species, five species of Myrmarachne (i.e. myrmecomorphic salticids), and 23 ordinary salticid species. Two categories of the myrmecomorphic salticids were recognized: (1) ‘typical Myrmarachne’ (four species with a strong resemblance to ants) and (2) Myrmarachne bakeri (a species with less strong resemblance to ants). Ants readily killed mantises in the laboratory, confirming that, for the mantises studied, ants are dangerous. In alternate-day testing, the mantises routinely preyed on the ordinary salticids, but avoided ants. The mantises reacted to myrmecomorphic salticids similarly to how they reacted to ants (i.e. myrmecomorphic salticids appear to be, for mantises, Batesian mimics of ants). Although myrmecomorphic salticids were rarely eaten, M. bakeri was eaten more often than typical Myrmarachne. Because the mantises had no prior experience with ants, ant mimics or ordinary salticids, our findings suggest that mantises have an innate aversion to attacking ants and that this aversion is generalized to myrmecomorphic salticids even in the absence of prior experience with ants. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 23–32.
TL;DR: An evolutionary scenario is proposed to account for the historical diversification of floodplain specialist species in Amazonia, with tentatively dated as occurring over the last 18 000 years BP, following a period of increased river stages throughout the basin.
Abstract: Phylogeographical and population genetics methods are used to reconstruct the diversification history of two species of the genus Xiphorhynchus (Aves: Dendrocolaptidae) associated with seasonally flooded forest types in Amazonia. Sequences of the mitochondrial gene cytochrome b were assessed for 21 and 30 individuals, belonging to eight and ten populations, of Xiphorhynchus kienerii and Xiphorhynchus obsoletus , respectively. Uncorrected genetic distances among unique haplotypes recovered ranged only from 0.01% to 0.4% for both species. Over 90% of the genetic variation detected in both species was partitioned within populations, and therefore was not structured geographically. Mismatch distributions and values of Tajima’s D -tests indicate that both X. kienerii and X. obsoletus have had small evolutionary effective population sizes, but experienced a recent demographic expansion. These demographic expansions are tentatively dated as occurring over the last 18 000 years BP, a time frame which coincides with the establishment of the early and mid-Holocene age floodplain forest in most of central and eastern Amazonia, following a period of increased river stages throughout the basin. Based on phylogenetic, phylogeographical, and populations genetics data obtained for X. kienerii and X. obsoletus , an evolutionary scenario is proposed to account for the historical diversification of floodplain specialist species in Amazonia. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 383‐395.
TL;DR: Flight performance and wing kinematics and flight morphology andFlight morphology in the butterfly Pararge aegeria (L.) using a tethered tarsal reflex induced flight set-up under laboratory conditions were experimentally quantified and the relationship between aspect ratio and wing stroke amplitude was sex-specific.
Abstract: Many evolutionary ecological studies have documented sexual dimorphism in morphology or behaviour. However, to what extent a sex-specific morphology is used differently to realize a certain level of behavioural performance is only rarely tested. We experimentally quantified flight performance and wing kinematics (wing beat frequency and wing stroke amplitude) and flight morphology (thorax mass, body mass, forewing aspect ratio, and distance to centre of forewing area) in the butterfly Pararge aegeria (L.) using a tethered tarsal reflex induced flight set-up under laboratory conditions. On average, females showed higher flight performance than males, but frequency and amplitude did not differ. In both sexes, higher flight performance was partly determined by wing beat frequency but not by wing stroke amplitude. Dry body mass, thorax mass, and distance to centre of forewing area were negatively related to wing beat frequency. The relationship between aspect ratio and wing stroke amplitude was sex-specific: females with narrower wings produced higher amplitude whereas males show the opposite pattern. The results are discussed in relation to sexual differences in flight behaviour. (c) 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 675-687.
TL;DR: Microsatellite DNA from museum specimens over 100 years old of the adonis blue butterfly, Polyommatus bellargus, are amplified to reinforce the enormous potential of museum specimens in well represented taxa such as butterflies for examining the effects of demographic events spanning many years.
Abstract: We amplified microsatellite DNA from museum specimens over 100 years old of the adonis blue butterfly, Polyommatus bellargus. These results were compared with butterfly samples taken from the same site near Folkestone in southern UK in 1998/9, 200 generations later, and with samples from other extant UK populations. Dramatic changes in allele frequencies have occurred over time, which is indicative of substantial genetic drift or extinction/recolonization. Patterns of heterozygosity in the 1998/9 sample are indicative of a past bottleneck, and one was known to have occurred in the late 1970s in this and many other UK populations. One allele present at high frequency in 1896 was not detected in any extant UK population, suggesting that it may have been lost from the UK (a 'ghost' allele), although the allele may well persist elsewhere within the range of the species. Although the present study is relatively small in scale (20 museum specimens from one site), it serves to reinforce the enormous potential of museum specimens in well represented taxa such as butterflies for examining the effects of demographic events spanning many years. (c) 2006 The Linnean Society of London.
TL;DR: Analysis of sequence data from the mitochondrial 12S, tRNAval, 16S, and cytochrome b, and the nuclear Rag2, to evaluate species boundaries and infer relationships among extant taxa suggests that mormoopids diversified in northern Neotropics before entering South America.
Abstract: The traditional explanation of the distribution of the Mormoopidae is that this family originated in southern Central America or northern South America, later expanding its range north to Mexico and the West Indies, and differentiating into eight species. An alternative fossil-based hypothesis argues that the family originated in the northern Neotropics, reached the Caribbean early in its history, and dispersed to South America after the completion of the Isthmus of Panama. The present study analyses new and previously published sequence data from the mitochondrial 12S, tRNAval, 16S, and cytochrome b, and the nuclear Rag2, to evaluate species boundaries and infer relationships among extant taxa. Fixed differences in cytochrome b often coincide with published morphological characters and show that the family contains at least 13 species. Two additional, morphologically indistinct, lineages are restricted to Suriname and French Guiana. Phylogeny-based inferences of ancestral area are equivocal on the geographical origin of mormoopids, in part because several internal nodes are not resolved with the available data. Divergences between Middle American and Antillean populations are greater than those between Mexico/Central America and South America. This suggests that mormoopids diversified in northern Neotropics before entering South America. A northern neotropical origin for mormoopids is congruent with both the Tertiary fossil record and recent phylogenetic hypotheses for the sister family to the Mormoopidae, the Phyllostomidae.
TL;DR: A priority-effect model is developed to reconcile the general lack of contemporary sympatry between closely related OTUs with the substantial historical connectivity among Mesoamerican drainages demonstrated by the rapid expansion of Brycon, Bryconamericus, and Cyphocharax.
Abstract: We present a phylogeographical analysis of four genera of Mesoamerican primary freshwater fish ( Brycon , Bryconamericus , Eretmobrycon , and Cyphocharax ). Three hundred and thirty-nine individuals were genotyped into one of 31 operational taxonomic units (OTUs) based on the nucleotide sequence of their mitochondrial ATPase 6 & 8 genes (842‐839 bp). Contrary to inference based on the species-level taxonomy of these genera, molecular data identified only a single case of sympatry between closely related OTUs, despite extensive parapatry. Polytomies dominate the mtDNA-based phylogenies and demonstrate multiple, noncontemporaneous waves of rapid expansion across Mesoamerica from South American sources. Analyses based on genetic distances observed among congeneric species of Mesoamerican primary freshwater fishes in comparison to divergence between transisthmian marine fishes permit the strong inference that the Pliocene rise of the Panama land bridge provided the first opportunity for the colonization of Mesoamerica by Characiform fishes. We develop a priority-effect model, based on the assumption that genetically closely related OTUs share similar ecological niches, to reconcile the general lack of contemporary sympatry between closely related OTUs with the substantial historical connectivity among Mesoamerican drainages demonstrated by the rapid expansion of Brycon , Bryconamericus , and Cyphocharax . Finally, in most cases, we infer that the westerly limits of freshwater fish distributions in Mesoamerica are more consistent with being defined by ecological factors rather than by dispersal limitation. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 235‐255.
TL;DR: In this paper, a 521-bp sequence of mtDNA cytochrome b indicates a late Miocene or Pliocene dispersal from the north-eastern Pacific (California-Mexico) to the northwestern Pacific (Japan), followed by a Pleistocene migration from the North-western Pacific to Europe.
Abstract: Historical changes in the distributions of temperate species in response to Milankovitch climate cycles have been well documented in palaeontological studies and recently evaluated with phylogeographical methods. How these cycles influence biological diversity remains a matter of debate. Molecular surveys of terrestrial and freshwater fauna demonstrate glacial refugia in low latitudes and range expansions into high latitudes, but few genetic studies have assessed the corresponding impact on marine fauna. In the present study, mtDNA sequences (N = 84) are surveyed to understand the impact of long-term climate oscillations on ‘Old World’ anchovies (genus Engraulis), a monophyletic group occurring in north and south temperate zones of the eastern Atlantic and the western Pacific. The analysis of a 521-bp sequence of mtDNA cytochrome b indicates a late Miocene or Pliocene dispersal from the north-eastern Pacific (California–Mexico) to the north-western Pacific (Japan), followed by Pleistocene dispersal from the north-western Pacific to Europe. Geography mandates that populations in southern Africa and Australia were stepping-stones for this dispersal. However, neither population occupies an intermediate position in the mtDNA genealogy; both populations are more recently derived from their northern neighbours. Haplotype diversity is high (h = 0.93–0.97) in European, Australian, and Japanese anchovies, but low (h = 0.22) in the southern African population, where all haplotypes are more closely related to European specimens than to each other. These southern populations occupy a precarious position, lacking north–south coastlines that allow range shifts during climatic extremes. Recurring extinctions and episodic recolonizations from northern hemisphere populations are the likely results. In this case, ocean-climatic changes retard rather than enhance opportunities for evolutionary radiations. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 673–689.