Showing papers in "Biological Journal of The Linnean Society in 2007"
TL;DR: These guidelines include how to linearize the camera's response to changes in light intensity, equalize the different colour channels to obtain reflectance information, and produce a mapping from camera colour space to that of another colour space (such as photon catches for the cone types of a specific animal species).
Abstract: In understanding how visual signals function, quantifying the components of those patterns is vital. With the ever- increasing power and availability of digital photography, many studies are utilizing this technique to study the con- tent of animal colour signals. Digital photography has many advantages over other techniques, such as spectrometry, for measuring chromatic information, particularly in terms of the speed of data acquisition and its relatively cheap cost. Not only do digital photographs provide a method of quantifying the chromatic and achromatic content of spa- tially complex markings, but also they can be incorporated into powerful models of animal vision. Unfortunately, many studies utilizing digital photography appear to be unaware of several crucial issues involved in the acquisition of images, notably the nonlinearity of many cameras' responses to light intensity, and biases in a camera's processing of the images towards particular wavebands. In the present study, we set out step-by-step guidelines for the use of digital photography to obtain accurate data, either independent of any particular visual system (such as reflection values), or for particular models of nonhuman visual processing (such as that of a passerine bird). These guidelines include how to: (1) linearize the camera's response to changes in light intensity; (2) equalize the different colour channels to obtain reflectance information; and (3) produce a mapping from camera colour space to that of another colour space (such as photon catches for the cone types of a specific animal species). © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 211-237. ADDITIONAL KEYWORDS: camera calibration - colour vision - colour measurement - digital cameras - imaging - radiance - reflection - signals.
585 citations
TL;DR: Using DNA sequence data, this work reports the first nearly complete species phylogeny of bumble bees, including most of the 250 known species from the 38 currently recognized subgenera, and provides a firm foundation for reclassification and for evaluating character evolution in the bumble Bees.
Abstract: Bumble bees (Bombus Latreille) occupy a wide diversity of habitats, from alpine meadows to lowland tropical forest, yet they appear to be similar in morphology throughout their range, suggesting that behavioural adaptations play a more important role in colonizing diverse habitats. Notwithstanding their structural homogeneity, bumble bees exhibit striking inter- and intraspecific variation in colour pattern, purportedly the outcome of mimetic evolution. A robust phylogeny of Bombus would provide the framework for elucidating the history of their wide biogeographical distribution and the evolution of behavioural and morphological adaptations, including colour pattern. However, morphological studies of bumble bees have discovered too few phylogenetically informative characters to reconstruct a robust phylogeny. Using DNA sequence data, we report the first nearly complete species phylogeny of bumble bees, including most of the 250 known species from the 38 currently recognized subgenera. Bayesian analysis of nuclear (opsin, EF-1α, arginine kinase, PEPCK) and mitochondrial (16S) sequences results in a highly resolved and strongly supported phylogeny from base to tips, with clear-cut support for monophyly of most of the conventional morphology-based subgenera. Most subgenera fall into two distinct clades (short-faced and long-faced) associated broadly with differences in head morphology. Within the short-faced clade is a diverse New World clade, which includes nearly one-quarter of the currently recognized subgenera, many of which are restricted to higher elevations of Central and South America. The comprehensive phylogeny provides a firm foundation for reclassification and for evaluating character evolution in the bumble bees. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 161–188.
302 citations
TL;DR: It is shown that there is no particular syndrome of traits predictably associated with polydomy, and the existing theoretical predictions and empirical results on the ecology of polydomys and the impact ofpolydomy on social evolution and investment strategies are detailed.
Abstract: The correct identification of colony boundaries is an essential prerequisite for empirical studies of ant behaviour and evolution. Ant colonies function at various organizational levels, and these boundaries may be difficult to assess. Moreover, new complexity can be generated through the presence of spatially discrete subgroups within a more or less genetically homogeneous colony, a situation called polydomy. A colony is polydomous only if individuals (workers and brood) of its constituent nests function as a social and cooperative unit and are regularly interchanged among nests. This condition was previously called polycalic, and the term polydomy was used in a broader sense for a group of daughter nests of the same mother colony (implying limited female dispersal), without regard to whether these different nests continued to exchange individuals. We think that this distinction between ‘polycaly’ and ‘polydomy’ concerns two disparate concepts. We thus prefer the narrower definition of polydomy, which groups individuals that interact socially. Does this new level of organization affect the way in which natural selection acts on social traits? Here, after examining the history of terms, we review all ant species that have been described as expressing polydomous structures. We show that there is no particular syndrome of traits predictably associated with polydomy. We detail the existing theoretical predictions and empirical results on the ecology of polydomy, and the impact of polydomy on social evolution and investment strategies, while carefully distinguishing monogynous from polygynous species. Finally, we propose a methodology for future studies and offer ideas about what remains to be done. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 319–348.
201 citations
TL;DR: The more consistent the outgroup root is, the more successful the MPR method appears to be, particularly for cases where a proper outgroup is unavailable.
Abstract: The outgroup method is widely used to root phylogenetic trees. An accurate root indication, however, strongly depends on the availability of a proper outgroup. An alternate rooting method is the midpoint rooting (MPR). In this case, the root is set at the midpoint between the two most divergent operational taxonomic units. Although the midpoint rooting algorithm has been extensively used, the efficiency of this method in retrieving the correct root remains untested. In the present study, we empirically tested the success rate of the MPR in obtaining the outgroup root for a given phylogenetic tree. This was carried out by eliminating outgroups in 50 selected data sets from 33 papers and rooting the trees with the midpoint method. We were thus able to compare the root position retrieved by each method. Data sets were separated into three categories with different root consistencies: data sets with a single outgroup taxon (54% success rate for MPR), data sets with multiple outgroup taxa that showed inconsistency in root position (82% success rate), and data sets with multiple outgroup taxa in which root position was consistent (94% success rate). Interestingly, the more consistent the outgroup root is, the more successful MPR appears to be. This is a strong indication that the MPR method is valuable, particularly for cases where a proper outgroup is unavailable.
182 citations
TL;DR: The results using data for 632 worker patterns from all of the world’s bumblebee species show that: (1) there are many repeating colour patterns, forming relatively few groups of species with similar patterns; (2) colour-pattern groups can be recognized using simple rules; and (3) species within the 24 largest colour- pattern groups are significantly aggregated in particular areas of the World.
Abstract: Bumblebee colour patterns can be highly variable within species, but are often closely similar among species. The present study takes a quantitative approach to survey bumblebee colour patterns in order to address some of the most basic questions concerning resemblances: (1) do colour-pattern groups exist; (2) are species within colour-pattern groups geographically clumped; and (3) are some colour-pattern groups associated with particular kinds of habitat? The results using data for 632 worker patterns from all of the world’s bumblebee species show that: (1) there are many repeating colour patterns, forming relatively few groups of species with similar patterns; (2) colour-pattern groups can be recognized using simple rules; and (3) species within the 24 largest colour-pattern groups are significantly aggregated in particular areas of the world. Three principal divisions of colour-pattern groups are associated with three likely functions: (1) the darkest bumblebees are associated primarily with the tropics, where a thermoregulatory function is suggested; (2) the palest bumblebees are associated with intermediate northern latitudes, where a cryptic function in drying grasslands is suggested; and (3) the intermediate, strongly banded bumblebees are widespread, although these patterns predominate where banding may have advantages as collective warning signals to predators (Mullerian mimicry). Further studies are needed to test these explanations. © The Natural History Museum, London. Journal compilation © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 97–118.
164 citations
TL;DR: The results corroborate previous hypotheses based on sequence data in showing that Heliconius is paraphyletic, with Laparus doris and Neruda falling within the genus, demonstrating a single origin for pollen feeding but with a loss of the trait in Neruda.
Abstract: Phylogenetic information is useful in understanding the evolutionary history of adaptive traits. Here, we present a well-resolved phylogenetic hypothesis for Heliconius butterflies and related genera. We use this tree to investigate the evolution of three traits, pollen feeding, pupal-mating behaviour and larval gregariousness. Phylogenetic relationships among 60 Heliconiina species (86% of the subtribe) were inferred from partial DNA sequences of the mitochondrial genes cytochrome oxidase I, cytochrome oxidase II and 16S rRNA, and fragments of the nuclear genes elongation factor-1α, apterous, decapentaplegic and wingless (3834 bp in total). The results corroborate previous hypotheses based on sequence data in showing that Heliconius is paraphyletic, with Laparus doris and Neruda falling within the genus, demonstrating a single origin for pollen feeding but with a loss of the trait in Neruda. However, different genes are not congruent in their placement of Neruda; therefore, monophyly of the pollen feeding species cannot be ruled out. There is also a highly supported monophyletic ‘pupal-mating clade’ suggesting that pupal mating behaviour evolved only once in the Heliconiina. Additionally, we observed at least three independent origins for larval gregariousness from a solitary ancestor, showing that gregarious larval behaviour arose after warning coloration. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 221–239.
149 citations
TL;DR: The data did not support the primary influence of geographical barriers or rivers in the intraspecific diversification of X. fuscus in the southern Atlantic forest, but supported the influence of isolation by geographical distance, recent vicariance events, and demographic expansions apparently related to Pleistocene and Holocene forest dynamics.
Abstract: Knowledge of the evolutionary processes that shaped a biota is important for both academic and conservation purposes. The objective of the present study is to analyse the mitochondrial genetic variation of Xiphorhynchus fuscus (Aves: Dendrocolaptidae) from the southern Atlantic forest in Brazil and Argentina, and to discuss whether the results support different hypotheses regarding the local intraspecific diversification of this species. We sequenced 575 bp of the control region of 114 specimens collected in the Brazilian states of Bahia, Minas Gerais, Rio de Janeiro, Sao Paulo, Parana, and Santa Catarina, and in the province of Misiones in Argentina. We studied the population genetic structure with analysis of molecular variance and the demographic history with multiple regression analysis, coalescence simulations, and demographic tests. Xiphorhynchus fuscus presented a significant population genetic structure (Φst = 0.57). Three mitochondrial lineages were described, one associated with Xiphorhynchus fuscus tenuirostris and the others with Xiphorhynchus fuscus fuscus. The data did not support the primary influence of geographical barriers or rivers in the intraspecific diversification of X. fuscus in the southern Atlantic forest. Instead, the data supported the influence of isolation by geographical distance, recent vicariance events, and demographic expansions apparently related to Pleistocene and Holocene forest dynamics. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 73–84.
141 citations
TL;DR: It is suggested that a behavioural syndrome exists in G. integer, in which more aggressive males are also more active in general, and possibly less cautious towards predation risk.
Abstract: Behavioural syndromes, or suites of correlated behaviours across different contexts and situations, have recently drawn attention from evolutionary biologists. In the field cricket Gryllus integer, males are aggressive with one another and fight vigorously over females and territories. We examined whether aggressiveness with other males was correlated with activity in a potentially dangerous context (a novel environment) in laboratory-raised virgin males. Aggressiveness was measured as fighting ability against a weight-matched opponent. First, we measured each cricket’s latency to become active in a novel environment and latency to emerge from a refuge within a novel environment. Next, we determined which of two weight-matched males was more aggressive, by pitting the males together in an agonistic contest and counting the number of fights won by each male. More aggressive males, who won more fights, had shorter latencies to become active when placed in a novel environment and shorter latencies to emerge from a safe refuge. These results suggest that a behavioural syndrome exists in G. integer, in which more aggressive males are also more active in general, and possibly less cautious towards predation risk. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 475–482.
136 citations
TL;DR: The present study recorded vertebral counts and measurements of vertebral aspect ratio from museum specimens for 54 species representing seven groups of actinopterygian fishes and found that the number of vertebrae can increase independently in the abdominal and caudal regions of the vertebral column, but changes in aspect ratio occur similarly in both regions.
Abstract: Within the ray-finned fishes, eel-like (extremely elongate) body forms have evolved multiple times from deeper-bodied forms. Previous studies have shown that elongation of the vertebral column may be associated with an increase in the number of vertebrae, an increase in the length of the vertebral centra, or a combination of both. Because the vertebral column of fishes has at least two anatomically distinct regions (i.e. abdominal and caudal), an increase in the number and relative length of the vertebrae could be region-specific or occur globally across the length of the vertebral column. In the present study, we recorded vertebral counts and measurements of vertebral aspect ratio (vertebral length/width) from museum specimens for 54 species representing seven groups of actinopterygian fishes. We also collected, from published literature, vertebral counts for 813 species from 14 orders of actinopterygian and elasmobranch fishes. We found that the number of vertebrae can increase independently in the abdominal and caudal regions of the vertebral column, but changes in aspect ratio occur similarly in both regions. These findings suggest that abdominal vertebral number, caudal vertebral number, and vertebral aspect ratio are controlled by separate developmental modules. Based on these findings, we suggest some candidate developmental mechanisms that may contribute to vertebral column patterning in fishes. Our study is an example of how comparative anatomical studies of adults can generate testable hypotheses of evolutionary changes in developmental mechanisms. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 97‐116.
136 citations
TL;DR: The observed dimorphism in bite force in A. carolinensis is not merely the result of an increase in head size, but involves distinct morphological changes in skull structure and the associated jaw adductor musculature.
Abstract: In many species of lizards, males attain greater body size and have larger heads than female lizards of the same size. Often, the dimorphism in head size is paralleled by a dimorphism in bite force. However, the underlying functional morphological basis for the dimorphism in bite force remains unclear. Here, we test whether males are larger, and have larger heads and bite forces than females for a given body size in a large sample of Anolis carolinensis. Next, we test if overall head shape differs between the sexes, or if instead specific aspects of skull shape can explain differences in bite force. Our results show that A. carolinensis is indeed dimorphic in body and head size and that males bite harder than females. Geometric morphometric analyses show distinct differences in skull shape between males and females, principally reflecting an enlargement of the jaw adductor muscle chamber. Jaw adductor muscle mass data confirm this result and show that males have larger jaw adductors (but not jaw openers) for a given body and head size. Thus, the observed dimorphism in bite force in A. carolinensis is not merely the result of an increase in head size, but involves distinct morphological changes in skull structure and the associated jaw adductor musculature. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 111–119.
119 citations
TL;DR: The results obtained revealed high population and haplotype divergence, suggesting restriction to the specific habitat of granite outcrops over long time frames with genetic drift as the most significant evolutionary force.
Abstract: Granite outcrops represent an isolated island habitat and, in ancient landscapes, may harbour species with complex evolutionary histories. Phylogenetic analysis of these species may reveal the influences of evolutionary processes over long time frames. Phylogenetic relationships from chloroplast and nuclear genome analysis were investigated in Eucalyptus caesia, a bird-pollinated mallee endemic to granite outcrops in the South-western Australian Floristic Region. The results obtained revealed high population and haplotype divergence, suggesting restriction to the specific habitat of granite outcrops over long time frames with genetic drift as the most significant evolutionary force. The hypothesis of derivation of ssp. magna from ssp. caesia was not supported by the pattern of diversity in either the chloroplast or the nuclear genome and the two subspecies were not monophyletic. Eucalyptus caesia displays significant clonality yet little evidence of inbreeding depression, suggesting deleterious mutations causing inbreeding depression have been purged. © 2008 Department of Environment and Conservation. Journal compilation © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 177–188.
TL;DR: Relationships between forms are weakly supported both by population and individual clustering methods, suggesting a scenario of a rapid diversification that contrasts to the clear bifurcating model assumed from previous mtDNA analyses.
Abstract: Combining different sources of information is essential for a complete understanding of the process of genetic differentiation between species. The Iberian and North African wall lizard (Podarcis) species complex has been the object of several studies regarding morphological and mitochondrial DNA variation but, so far, no large-scale survey of nuclear variation within this group has been accomplished. In this study, ten polymorphic allozyme loci were studied in 569 individuals collected across the Iberian Peninsula and North Africa. The obtained data were analysed using both conventional population genetic tools and recent Bayesian model-based clustering methods. Our results show that there are several well-differentiated entities corroborating the major splits observed in mtDNA analyses. These groups correspond not only to the fully recognized species Podarcis bocagei, Podarcis carbonelli, and Podarcis vaucheri but also to multiple forms within the polytypic Podarcis hispanica, all of which have a similar level of differentiation to that observed between the acknowledged species. However, relationships between forms are weakly supported both by population and individual clustering methods, suggesting a scenario of a rapid diversification that contrasts to the clear bifurcating model assumed from previous mtDNA analyses. Individual multilocus analyses report few individuals misassigned or apparently admixed, some of which are most likely explained by the persistence of high levels of ancestral polymorphism. Other admixed individuals, however, are probably the result of limited levels of gene flow between forms. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 121–133.
TL;DR: The patterns of genetic and phenotypic divergence as well as the types of isolating barriers that are present between two sympatric pairs of threespine sticklebacks in Hokkaido, Japan are characterized.
Abstract: The threespine stickleback (Gasterosteus aculeatus) species complex is well suited for identifying the types of phenotypic divergence and isolating barriers that contribute to reproductive isolation at early stages of speciation. In the present study, we characterize the patterns of genetic and phenotypic divergence as well as the types of isolating barriers that are present between two sympatric pairs of threespine sticklebacks in Hokkaido, Japan. One sympatric pair consists of an anadromous and a resident freshwater form and shows divergence in body size between the forms, despite the lack of genetic differentiation between them. The second sympatric pair consists of two anadromous forms, which originated before the last glacial period and are currently reproductively isolated. These two anadromous forms have diverged in many morphological traits as well as in their reproductive behaviours. Both sexual isolation and hybrid male sterility contribute to reproductive isolation between the anadromous species pair. We discuss the shared and unique aspects of phenotypic divergence and reproductive isolation in the Japanese sympatric pairs compared with postglacial stickleback species pairs. Further studies of these divergent species pairs will provide a deeper understanding of the mechanisms of speciation in sticklebacks. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 671–685.
TL;DR: The bacterial diversity associated with several representatives of three species groups of the arboreal ant genus Tetraponera was examined based on genes encoding 16S rRNA, citrate synthase and a structural protein of the dinitrogenase complex ( nifH).
Abstract: Tropical arboreal ants mainly feed as 'secondary herbivores', relying mostly on nitrogen-poor homopteran exudates as food. It has been speculated that this nitrogen-limitation of their diet may be overcome by nutritional upgrading with the help of symbiotic bacteria. We examined the bacterial diversity associated with several representatives of three species groups of the arboreal ant genus Tetraponera based on genes encoding 16S rRNA, citrate synthase and a structural protein of the dinitrogenase complex ( nifH ). The bacterial microflora showed group-specificity, suggest- ing long-term association between ants and bacteria. In all specimens of four species of the nigra group, we detected bacteria closely related to Bartonella (order Rhizobiales). Ants of the allaborans group harboured bacteria belonging to the enterobacteria. In Tetraponera pilosa of the third species group, we found the enterobacterium Pantoea agglo- merans . In spite of the different phylogenetic affiliation of the bacteria identified in the three species groups, the presence of nifH in most species suggests a role in nitrogen metabolism of the bacterial microbiota. We also detected a high infection rate with the intracellular bacterium Wolbachia in all Tetraponera species groups. Besides the widespread bacteria found in Tetraponera , we discovered a diverse group of bacteria represented by single sequences. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 399-412. ADDITIONAL KEYWORDS: 16S rRNA - gut flora - Formicidae - nitrogen fixation - Rhizobiales - symbiosis - TGGE.
TL;DR: In this article, two modes of selection were tested, directional and stabilizing, and wing condition was compared between these two groups, and the results do not support the action of stabilizing selection: there was no significant variance between migrant and resident monarchs in their wing size or shape.
Abstract: The majority of migrant monarchs (Danaus plexippus) from the eastern USA and south-eastern Canada migrate to Mexico; however, some of them migrate to Cuba. Cuban migrants hatch in south-east Canada and eastern USA, and then engage in a southern trip of 4000 km to this Caribbean island. In Cuba, these migrants encounter resident monarchs, which do not migrate, and instead move between plant patches looking for nectar, mating partners and host plants. These differences in flight behaviour between migrant and resident Cuban monarchs may have resulted in different selective pressures in the wing size and shape. Two modes of selection were tested, directional and stabilizing. In addition, wing condition was compared between these two groups. Monarchs were collected for 4 years in Cuba and classified as resident or migrant using two independent techniques: Thin-layer chromatography and stable hydrogen and stable carbon isotope measurements. Wing size was measured and wing condition was rated in the butterflies. Fourier analysis and wing angular measurements were used to assess wing shape differences. Migrants have significantly longer wings than residents, thus supporting the action of directional selection on wing size. In addition, directional selection acts on wing shape; that is, migrant females differ significantly from resident females in their wing angles. However, the results do not support the action of stabilizing selection: there was no significant variance between migrant and resident monarchs in their wing size or shape. Also, migrant females and males differed in wing condition as a result of differences in flight behaviour. In conclusion, eastern North American monarchs offer a good opportunity to study the selective pressures of migration on wing morphology and how different migratory routes and behaviours are linked to wing morphology and condition. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 605–616.
TL;DR: It is shown that taxonomy has been integrative for most of its history although, in this sense, integrative does not mean the indiscriminate pooling of any source of data.
Abstract: Deep misunderstandings still besiege taxonomy after more than 200 years of fruitful output. It has been asserted in this journal that taxonomy should be integrative and conform to a series of restrictive guidelines. We show that taxonomy has been integrative for most of its history although, in our sense, integrative does not mean the indiscriminate pooling of any source of data. The guidelines proposed are not founded in good scientific rationale and can have, if followed, a detrimental effect not only on taxonomy, but also on biology as a whole. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 211–216.
TL;DR: There is not one single species but four separate species in the Mediterranean or sub Mediterranean areas of the world, conclusively revealing that Parmelina quercina are not cryptic species but morphologically recognizable taxa.
Abstract: Morphological and phylogenetic relationships of the worldwide Mediterranean lichen forming fungus, Parmelina quercina, have been studied. Specimens from western Europe, western North America and southern Australia were analysed using molecular data (nuITS rDNA, nuLSU rDNA and mtSSU rDNA) and selected morphological features (upper cortex maculae, scanning electron microscopy examination of the epicortex, ascospores and conidia shape and size, and amphithecial retrorse rhizines). The results conclusively reveal that: (1) there is not one single species but four separate species in the Mediterranean or sub Mediterranean areas of the world. Parmelina quercina and Parmelina carporrhizans (Euroasiatic species), Parmelina coleae sp. nov. (North America) and Parmelina elixia sp. nov. (Australia); (2) largely debated P. carporrhizans is not a synonym of P. quercina but supported as a valid species circumscribed to Macaronesic relict sites; (3) the geographical isolation of the Australian population is correlated with a large genetic distance; (4) morphological characters (ascospores and conidial variability and thallus epicortex) correlate with the phylogenetic hypothesis; (5) the new or revalidated species within Parmelina quercina are not cryptic species but morphologically recognizable taxa. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 455–467.
TL;DR: Adult sexual dimorphism for head characters in these species is the result of both shape differences in the immature stage and hypermetric growth of the head in relation to body size in males.
Abstract: Podarcis bocagei and Podarcis carbonelli are two lacertid species endemic to the western Iberian Peninsula, and both show head size and shape sexual dimorphism. We studied immature and adult head sexual dimorphism and analysed ontogenetic trajectories of head traits with body and head size, aiming to shed light on the proximate mechanisms involved. Immatures were much less dimorphic than adults, but geometric morphometric techniques revealed that head shape sexual differences are already present at this stage. Males and females differed in allometry of all head characters with body size, with males showing a disproportionate increase of head size and dimensions. On the other hand, head dimensions and head shape changed with increasing head size following similar trends in both sexes, possibly indicating developmental restrictions. Consequently, adult sexual dimorphism for head characters in these species is the result of both shape differences in the immature stage and hypermetric growth of the head in relation to body size in males. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 111–124.
TL;DR: A revision of the trilobed uncus Ostrinia spp.
Abstract: We reconsider the taxonomy of a group of closely related Ostrinia spp., illustrating how useful Mayr's biological spe- cies concept remains for studying speciation patterns and processes. We review and re-analyse recent data on Ostrinia scapulalis , Ostrinia nubilalis , Ostrinia narynensis and Ostrinia orientalis , along with those obtained over > 45 years in the former Soviet Union. The ten species of the 'trilobed uncus' group in the Ostrinia genus are clas- sified into subgroups according to male mid-tibia morphology. However, none of the characters that further discrim- inate between them (female sex pheromones, male genitalia and calling time) varies together with male mid-tibia morphology, and neither do molecular markers. Moreover, male mid-tibia morphology appears to depend on only two diallelic loci and seems to be unrelated to reproductive isolation between Ostrinia taxa. By contrast, reproductive iso- lation is strongly related to host-plant type. In accordance with Mayr's species concept, we thus propose a revision of the trilobed uncus Ostrinia spp. based primarily on host-plant type. We propose that O. narynensis Mutuura & Munroe, 1970 ( syn. nov. ) and O. orientalis Mutuura & Munroe, 1970 ( syn. nov. ) be synonymized with O. scapulalis (Walker, 1859). We further demonstrate that O. nubilalis auctt. pro parte feeding on mugwort, hop, and several other dicotyledons (previously called the ' O. nubilalis mugwort-race' in France) also belongs to O. scapulalis . Consequently, we propose that only O. nubilalis specimens feeding on maize (the former French ' O. nubilalis maize- race') belong to O. nubilalis (Hubner, 1796). The implications of this revision are discussed. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 49-72. ADDITIONAL KEYWORDS: biological species concept - host-races - Ostrinia furnacalis - Ostrinia narynensis - Ostrinia nubilalis - Ostrinia orientalis - Ostrinia scapulalis - speciation - taxonomy.
TL;DR: These findings are consistent with the idea that vocal divergence arising in small populations at the edge of Amazonia may result in partial reproductive isolation when contact is resumed, and suggest the possibility that song divergence in peripatry may act as a barrier to gene flow in suboscines.
Abstract: The evolutionary divergence of mating signals provides a powerful basis for animal speciation. Divergence in sympatry strengthens reproductive isolation, and divergence in allopatry can reduce or eliminate gene flow between populations on secondary contact. In birds, the first of these processes has empirical support, but the second remains largely hypothetical. This is perhaps because most studies have focused on oscine passerines, whose song learning ability may reduce the influence of vocalizations in reproductive isolation. In suboscine passerines, the role of learning in song development is thought to be minimal, and the resultant signals are relatively fixed. To investigate the role of song in the early stages of peripatric speciation, we therefore studied a suboscine, the chestnut-tailed antbird Myrmeciza hemimelaena. We recorded male songs in a natural forest island (isolated for < 3000 years) at the southern fringe of Amazonia, and at two nearby sites in continuous forest. A previous study found the isolated population to be weakly differentiated genetically from the ancestral population suggesting that peripatric speciation was underway. In support of this, although we detected minor but significant differences in song structure between each site, the most divergent songs were those of island birds. On simulating secondary contact using playback, we found that pairs from the forest island responded more strongly to island (i.e. local) songs than to those from both non-island sites, and vice versa. This pattern was not observed in pairs from one non-island site, which responded with equal strength to local songs and songs from the other non-island site. Island females were more likely to approach and sing after hearing local male songs, rather than songs from the non-island populations, and vice versa; non-island females did not appear to discriminate between local songs and those from the other non-island site. These findings are consistent with the idea that vocal divergence arising in small populations at the edge of Amazonia may result in partial reproductive isolation when contact is resumed. They also suggest the possibility that song divergence in peripatry may, after much longer time-frames, act as a barrier to gene flow in suboscines, perhaps because of an inability to learn or recognize divergent songs on secondary contact. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 173–188.
TL;DR: The validity of the righting response as a good candidate for a fitness index in aquatic turtles is supported and individual variability that is probably heritable and is indirectly correlated with survival is shown.
Abstract: Theoretical evolutionary ecology assumes the existence of fitness variability in natural populations. As realistic mea- sures of fitness are usually difficult to perform directly, integrating fitness indices are proposed in all taxa. In sauropsids, locomotor performances have been proposed as a good integrating index of fitness in natural populations. Concerning aquatic turtles, a performance trait that may be important for the survival of juveniles is the righting response of individuals when they are placed on their carapace. In the present study, we examined the righting response in juveniles of the red-eared slider turtle, Trachemys scripta elegans . We tested two different measures of the righting response for 170 juveniles from constant incubation temperature and for 86 juveniles from three sinu- soidal fluctuating incubation temperatures that are considered as more representative of natural conditions in the nest. We compared the effects of offspring sex, maternal identity, juvenile growth rate, and juvenile survival (i.e. indi- vidual characteristics), as well as the nutritional status of juveniles (i.e. experimental conditions), on the two dif- ferent measures of righting response and for each thermal incubation treatments of the eggs (i.e. experimental treatments). We observed that the effects of the individual characteristics were markedly different between the two measures of the righting response and between experimental treatments. These results highlight the importance of the choice of the measure and of the experimental conditions and treatments in the study of a phenotypic trait. Results obtained for only one performance measure under constant laboratory conditions must therefore be extrap- olated to the field with caution. Our results also show that the righting response presents individual variability that is probably heritable and is indirectly correlated with survival. These findings support the validity of the righting response as a good candidate for a fitness index in aquatic turtles. © 2007 The Linnean Society of London, Bio- logical Journal of the Linnean Society , 2007, 91 , 99-109.
TL;DR: This is the first detailed study showing that different colour perception by the birds can affect their responses towards the parasitic egg, and suggests that the combination of UV and visible ranges of the spectra plays a major role in the evolution of discrimination processes, as well as in the development of the mimicry of the parasitic Egg.
Abstract: Much attention has been devoted to understanding the evolution of egg mimicry in avian brood parasites. The majority of studies have been based on human perception when scoring the mimicry of the parasitic egg. Surprisingly, there has been no detailed study on the recognition and sensitivity towards differently coloured parasitic eggs. We investigated effect of different colours of the experimental eggs measured by ultraviolet (UV)-visible reflectance spectrophotometry on rejection behaviour in the song thrush (Turdus philomelos). We carried out a set of experiments with four blue model eggs representing mimetic eggs, whereas six other colours represented nonmimetic eggs. Our results revealed that two colours originally designed as a mimetic were rejected at a high rate, whereas one group of the nonmimetic was accepted. A multiple regression model of absolute differences between song thrush and experimental eggs on rejection rate showed that the level of mimicry in the UV and green parts of the colour spectrum significantly influenced egg rejection in the song thrush. To our knowledge, this is the first detailed study showing that different colour perception by the birds can affect their responses towards the parasitic egg. These findings suggest that the combination of UV and visible ranges of the spectra plays a major role in the evolution of discrimination processes, as well as in the evolution of the mimicry of the parasitic egg. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 269–276.
TL;DR: Stable isotope analysis provides a novel opportunity to integrate ecological and selective landscapes in order to identify underlying ecological mechanisms of selection and provide insight into the maintenance of variability in a free-living native black-tailed deer population.
Abstract: Interindividual variation in niche presents a potentially central object on which natural selection can act. This may have important evolutionary implications because habitat use governs a suite of selective forces encountered by foragers. In a free-living native black-tailed deer, Odocoileus hemionus , population from coastal British Columbia, we used stable isotope analysis to identify individual variation in foraging niche and investigated its relationship to fitness. Using an intragenerational comparison of surviving and nonsurviving O. hemionus over 2 years of predation by wolves, Canis lupus, we detected resource-specific fitness. Individuals with isotopic signatures that suggested they foraged primarily in cedar ( Thuja plicata )-dominated and low-elevation hemlock ( Tsuga heterophylla )dominated forest stands were more likely to be killed by C. lupus . High-quality forage in T. plicata stands, as indexed by protein content, may be involved in maintaining this foraging phenotype. Moreover, nonsurvivors diverged more than survivors from median isotopic signatures, suggesting selection against foraging specialization. Stable isotope analysis provides a novel opportunity to integrate ecological and selective landscapes in order to identify underlying ecological mechanisms of selection and provide insight into the maintenance of variability. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 125‐137.
TL;DR: The reconstructions suggest that the ancestral Maoricicada may have been preadapted to the alpine environment because it existed before the origin of high mountainous habitats, dwelt at mid-to-low altitudes, and yet possessed the classic alpine insect adaptations of heavy pubescence and dark coloration.
Abstract: We have used ancestral character state reconstruction and molecular dating to test hypotheses on the evolution of New Zealand alpine cicadas of the genus Maoricicada Dugdale. Gene trees were estimated from mitochondrial DNA and the nuclear loci elongation factor 1- α , period, and calmodulin and species-level relationships were reconstructed using gene tree parsimony. These analyses suggest that the alpine habitat character state had a single origin and that the ancestral Maoricicada lived in low to mid-elevation habitats. Our reconstructions also strongly support the hypothesis that this ancestor was darkly coloured and had increased pubescence, classic adaptations of alpine insects. Using relaxed-clock Bayesian dating methods, we estimated that the radiation of the alpine Maoricicada species was coincident with the late Miocene acceleration in the rate of uplift of the Southern Alps rather than uplift in the early Miocene. These dates are very similar to those of other alpine taxa, indicating that the New Zealand alpine biota is very young. Our reconstructions suggest that the ancestral Maoricicada may have been preadapted to the alpine environment because it existed before the origin of high mountainous habitats, dwelt at mid-to-low altitudes, and yet possessed the classic alpine insect adaptations of heavy pubescence and dark coloration. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 419‐435.
TL;DR: The role of innate and acquired resistance, and the findings in the context of natural gyrodactylid infections, are discussed.
Abstract: Resource availability, predation, and sexual selection have all been shown to play an important role in the ecology and evolution of guppies, Poecilia reticulata, but the role of parasitism has received comparatively little attention. In the present study, we examined natural infection levels of wild-caught guppies from the Upper and Lower Aripo River in Trinidad (UA and LA, respectively) and experimentally infected a subsample of fish with an isogenic line of the ectoparasite Gyrodactylus turnbulli. LA fish showed a superior resistance compared to UA guppies during the primary, but not secondary infection 53 days later. Resistance of LA individuals was consistent across experiments, suggesting immunocompetence has a heritable genetic basis. The efficiency of the immune response of UA fish was not correlated across infections. During primary infections, UA fish were highly susceptible, but their resistance was significantly improved during a secondary infection, highlighting the importance of acquired resistance. We discuss the role of innate and acquired resistance, and place our findings in the context of natural gyrodactylid infections.
TL;DR: There is better resolution and support for the more slowly evolving nuclear introns including a New World clade, indicating a single origin of emballonurid bats in the Neotropics, and one novel subtribe has a hard basal polytomy that is unresolved for all of the nuclear partitions, suggesting a rapid burst of evolution during the diversification of genera.
Abstract: Multiple unlinked loci are surveyed in a methodological approach for mammalian systematics that uses genes from the four pathways of genetic transmission: mitochondrial, autosomal, and X and Y sex chromosomes. Each of these components has different properties, such as effective population size, mutation rate, and recombination, that result in a robust hypothesis of evolutionary history. The utility of this experimental design is tested with bats in the family Emballonuridae and the hypothesis that the New World taxa are monophyletic. Parsimony and Bayesian analyses of the individual data sets give generally congruent topologies with high bootstrap proportions and posterior probabilities for monophyletic clades representing species and genera. The mitochondrial gene has significantly faster rates of substitution, higher levels of homoplasy, and a greater degree of saturation than the nuclear genes that contributed to the loss of phylogenetic signal at deeper branches of the tree. However, there is better resolution and support for the more slowly evolving nuclear introns including a New World clade, indicating a single origin of emballonurid bats in the Neotropics (tribe Diclidurini). One novel subtribe has a hard basal polytomy that is unresolved for all of the nuclear partitions, suggesting a rapid burst of evolution during the diversification of genera. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 189–209.
TL;DR: The results suggest that environmental conditions are the primary force structuring the seasonal activity of the ant assemblages studied here, especially at low-elevation sites.
Abstract: In this study, we use 12 months of data from 11 ant assemblages to test whether seasonal variation in ant diversity is governed by either the structuring influences of interspecific competition or environmental conditions. Because the importance of competition might vary along environmental gradients, we also test whether the signature of competition depends on elevation. We find little evidence that competition structures the seasonal patterns of activity in the ant assemblages considered, but find support for the effects of temperature on seasonal patterns of diversity, especially at low-elevation sites. Although, in general, both competition and the environment interact to structure ant assemblages, our results suggest that environmental conditions are the primary force structuring the seasonal activity of the ant assemblages studied here.
TL;DR: The combination of the phylogeny with the fossil evidence suggests that present day diversity in IWP Turbo is the result of the evolutionary persistence within the IWP of several, morphologically distinct lineages, some of which were more widespread in the Oligocene.
Abstract: The present study aimed to assess the consequences of tectonic events and temperature regime on the diversification of Indo-West Pacific (IWP) turban shell species. Bayesian and parsimony methods were used to construct a phylogenetic hypothesis using sequence data from three genes for the turban shell genus Turbo and for a larger data set including representatives of all known genera in the subfamily Turbininae. Phylogenetic analyses indicate that all IWP Turbo species form a single clade approximately 68 Myr in age, predating the closure of the Tethys Sea and therefore predating the physical separation of the IWP from other biogeographical regions. All but one of the IWP subgenera tested in Turbo also predate the closure of the Tethys Sea. Fossil evidence for Marmarostoma, the largest subgenus, confirms that at least some Turbo lineages currently restricted to the IWP were previously more widespread. The combination of the phylogeny with the fossil evidence suggests that present day diversity in IWP Turbo is the result of the evolutionary persistence within the IWP of several, morphologically distinct lineages, some of which were more widespread in the Oligocene. Some IWP lineages show significant increases in diversification in the early Miocene, probably as a result of the increased availability of both shallow-water habitats due to tectonic plate movements and increased carbonate platforms in the central IWP resulting from coincident diversification of zooxanthellate corals. The IWP is therefore behaving as both a cradle of diversity (with new species originating in situ) and a museum of diversity (with lineages that predate its isolation also being maintained). Bayesian and parsimony analyses of the subfamily recovered five clades and mapping the temperature regime (tropical or temperate) of each species onto the molecular tree using parsimony suggested that temperate habitat is an ancestral character in at least four of the clades. This result was also supported by Bayesian reconstruction of ancestral states. Astralium (the fifth clade) may also prove to have a temperate origin, but this could not be determined with certainty given the available data. The origin of diversity in tropical regions is of particular interest because it has been suggested that the tropics are the source of many evolutionary novelties and have provided a species pool, from which temperate regions were populated. The present study suggests that Turbininae may be an exception to this rule. The tree shape also suggests that temperature has had an effect on speciation rates; temperate Turbininae are apparently evolving more slowly or suffering more extinction than their tropical sister clades, which show greater diversity. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 573–592.
TL;DR: Results strongly support the monophyly of the superfamily and one of the two families, Platygastridae, but the Scelionidae are most likely polyphyletic, while illustrating the problems associated with the current classification is the nonmonophyle of a number of genera, namely Opisthacantha Caloteleia, Telenomus, Trimorus, Teleas and Idris.
Abstract: The Platygastroidea are a diverse group of mostly small to tiny wasps, the common biology for which is endoparasitism of insect and spider eggs. No analytically-based phylogeny exists for the superfamily, and the current suprageneric classification is flawed in part because of its reliance on homoplasious and pleisiomorphic morphological characters. To determine platygastroid relationships as a basis for investigating host and ovipositor evolution, phylogenies of > 70 in-group species (representing 55 genera) were reconstructed by parsimony and Bayesian methods using three molecular markers; the mitochondrial cytochrome oxidase I and the nuclear genes 28S and 18S rRNA. The results strongly support the monophyly of the superfamily and one of the two families, Platygastridae, but the Scelionidae are most likely polyphyletic. However, within the Scelionidae, there is a well supported ‘main scelionid clade’ that contains the majority of genera assigned to the family. At the subfamilial level, both putative subfamilies of Platygastridae, the Platygastrinae, and Sceliotrachelinae, are likely to be polyphyletic. Within the Scelionidae, both the Teleasinae and Telenominae are monophyletic, but the Scelioninae is clearly not so. The current tribal classification for the Scelionidae is in need of major reassessment because no tribes, with the exception of the Scelionini s.s., were found to be monophyletic. Further illustrating the problems associated with the current classification is the nonmonophyly of a number of genera, namely Opisthacantha Caloteleia, Telenomus, Trimorus, Teleas and Idris. Analysis of ovipositor evolution in the superfamily revealed that the Ceratobaeus-type ovipositor system is ancestral; however, this trait was lost prior to the evolution of the main scelionid clade, for which the Scelio-type ovipositor system is ancestral and defines a mostly paraphyletic assemblage. Ancestral state analysis indicates that the Ceratobaeus-type ovipositor was subsequently re-evolved in the main scelionid clade, representing a possible contradiction of Dollo’s law. Previously, the tribal placement has been used to predict the host associations of genera for which host data were unavailable. However, the fact that most tribes are not monophyletic throws into doubt any such speculation based on the current classification. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 653–669.
TL;DR: These estimates would be especially interesting for Mesozoic non-avian theropod dinosaurs and Permian and Triassic therapsids to investigate, respectively, the origin of avian and mammalian endothermy.
Abstract: We explored the factors that explain the variation in resting metabolic rates (RMR) in growing amniotes by using the phylogenetic comparative method. For this, we measured raw RMR (mL O2 h−1), body mass, body mass growth rate, and periosteal bone growth rate in a sample of 44 growing individuals belonging to 13 species of amniotes. We performed variation partitioning analyses, which showed that phylogeny explains a significant fraction of the variation of mass-specific RMR (mL O2 h−1 g−1), and that the cost of growth is much higher than the cost of maintenance. Moreover, we tested the hypothesis of the independence of energy allocation, and found that maintenance metabolism and growth rates are not significantly related. Finally, we calculated the statistical parameters of the relationship between geometry-corrected RMR (mL O2 h−1 g−0.67) and bone growth rate. This relationship could potentially be used in palaeobiology to infer RMR from bone tissue samples of fossil species by assuming Amprino’s rule (according to which bone tissue types reflect bone growth rates). These estimates would be especially interesting for Mesozoic non-avian theropod dinosaurs and Permian and Triassic therapsids to investigate, respectively, the origin of avian and mammalian endothermy. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 63–76.