Showing papers in "Biological Journal of The Linnean Society in 2001"
TL;DR: Analysis of patterns of animal dispersal, vicariance and diversification in the Holarctic based on complete phylogenies of 57 extant non-marine taxa shows that trans-Atlantic distributions were common in the Early–Mid Tertiary whereas transBeringian distributions were rare in that period.
Abstract: We analysed patterns of animal dispersal, vicariance and diversification in the Holarctic based on complete phylogenies of 57 extant non-marine taxa, together comprising 770 species, documenting biogeographic events from the Late Mesozoic to the present. Four major areas, each corresponding to a historically persistent landmass, were used in the analyses: eastern Nearctic (EN), western Nearctic (WN), eastern Palaeoarctic (EP) and western Palaeoarctic (WP). Parsimony-based tree fitting showed that there is no significantly supported general area cladogram for the dataset. Yet, distributions are strongly phylogenetically conserved, as revealed by dispersalvicariance analysis (DIVA). DIVA-based permutation tests were used to pinpoint phylogenetically determined biogeographic patterns. Consistent with expectations, continental dispersals (WP↔EP and WN↔EN) are significantly more common than palaeocontinental dispersals (WN↔EP and EN↔WP), which in turn are more common than disjunct dispersals (EN↔EP and WN↔WP). There is significant dispersal asymmetry both within the Nearctic (WN→EN more common than EN→WN) and the Palaeoarctic (EP→WP more common than WP→EP). CrossBeringian faunal connections have traditionally been emphasized but are not more important than cross-Atlantic connections in our data set. To analyse changes over time, we sorted biogeographic events into four major time periods using fossil, biogeographic and molecular evidence combined with a ‘branching clock’. These analyses show that trans-Atlantic distributions (EN–WP) were common in the Early–Mid Tertiary (70–20 Myr), whereas transBeringian distributions (WN–EP) were rare in that period. Most EN–EP disjunctions date back to the Early Tertiary (70–45 Myr), suggesting that they resulted from division of cross-Atlantic rather than cross-Beringian distributions. Diversification in WN and WP increased in the Quaternary (< 3 Myr), whereas in EP and EN it decreased from a maximum in the Early–Mid Tertiary. 2001 The Linnean Society of London
603 citations
TL;DR: An alternative approach is discussed, termed sequence heterochrony, in which a developmental trajectory is conceptualized as a series of discrete events in which the sequence position of an event changes relative to other events in that sequence.
Abstract: The concept of heterochrony is a persistent component of discussions about the way that evolution and development interact. Since the late 1970s heterochrony has been defined largely as developmental changes in the relationship of size and shape. This approach to heterochrony, here termed growth heterochrony, is limited in the way it can analyse change in the relative timing of developmental events in a number of respects. In particular, analytical techniques do not readily allow the study of changes in developmental events not characterized by size and shape parameters, or of many kinds of events in many taxa. I discuss here an alternative approach to heterochrony, termed sequence heterochrony, in which a developmental trajectory is conceptualized as a series of discrete events. Heterochrony is demonstrated when the sequence position of an event changes relative to other events in that sequence. I summarize several analytical techniques that allow the investigation of sequence heterochrony in phylogenetic contexts and also quantitatively. Finally, several examples of how this approach may be used to test hypotheses on the way development evolves are summarized.
262 citations
TL;DR: This investigation suggests that long-term studies evaluating spatial and temporal patterns of species diversity among many sites may be required for a better understanding of tropical communities and how best to conserve them.
Abstract: To test the veracity of previous studies and illuminate major community patterns from an intact community, a guild of nymphalid butterflies was sampled at monthly intervals for five consecutive years by trapping in the canopy and understorey of five contiguous forest plots in the same rainforest Significant numbers of species belonged to either the canopy or understorey fauna, confirming fundamental vertical stratification, and showing that sampling in one vertical position is a poor estimator of diversity Significant monthly variation showed that intermittent or short-term sampling would underestimate diversity, and significant variation among years and areas showed that diversity was strongly influenced by sampling year Even when the underlying communities were the same, temporal interactions strongly affected species diversity in both horizontal and vertical dimensions An unprecedented seasonal inversion of species richness and abundance was detected between the canopy and understorey that occurred at the onset of all rainy seasons This investigation suggests that long-term studies evaluating spatial and temporal patterns of species diversity among many sites may be required for a better understanding of tropical communities and how best to conserve them
240 citations
TL;DR: The most significant variables are those related to altitude, and particularly maximum altitude, whose cubic response reflects the occurrence of the maximum number of species at the highest altitudes.
Abstract: Using an exhaustive data compilation, Iberian vascular plant species richness in 50×50 UTM grid cells was regressed against 24 explanatory variables (spatial, geographical, topographical, geological, climatic, land use and environmental diversity variables) using Generalized Linear Models and partial regression analysis in order to ascertain the relative contribution of primary, heterogeneous and spatially structured variables. The species richness variation accounted for by these variables is reasonably high (65% of total deviance). Little less than half of this variation is accounted for spatially structured variables. A purely spatial component of variation is hardly significant. The most significant variables are those related to altitude, and particularly maximum altitude, whose cubic response reflects the occurrence of the maximum number of species at the highest altitudes. This result highlighted the importance of Iberian mountains as hotspots of diversity and the relevance of large and small scale historical factors in contemporary plant distribution patterns. Climatic or energy-related variables contributed little, whereas geological (calcareous and acid rocks) and, to a lesser extent, environmental heterogeneity variables (land use diversity and altitude range) seem to be more important.
195 citations
TL;DR: It is argued that the persistence of mutualism is best understood by using theories ofspecies coexistence, because each mutualist can be considered a resource for the other, and species coexistence theory explains how multiple taxa can stably partition a resource over multiple generations.
Abstract: Cooperation invites cheating, and nowhere is this more apparent than when different species cooperate, known as mutualism. In almost all mutualisms studied, specialist parasites have been identified that purloin the benefits that one mutualist provides another. Explaining how parasites are kept from driving mutualisms extinct remains an unsolved problem because existing theories explaining the maintenance of cooperation do not apply to parasites of mutualisms. Nonetheless, these theories can be summarized in such a way as to suggest how mutualisms can persist in the face of parasites. (1) For cooperation to occur, the recipient of a benefit must reciprocate, and the recriprocated benefit must be captured by the initial giver or its offspring. (2) For cooperation to persist, the mutualism must be re-assembled each generation. Because most mutualisms are of the “by-product‘ type, broadly defined, the first condition is normally always fulfilled. Thus, the maintenance of mutualism usually requires enforcement of the second condition: reliable re-assembly. Hence, I argue that the persistence of mutualism is best understood by using theories of species coexistence, because each mutualist can be considered a resource for the other, and species coexistence theory explains how multiple taxa (e.g. parasites and mutualists) can stably partition a resource over multiple generations. This approach connects the study of mutualism to theories of population regulation and helps to identify key factors that have promoted the evolution, maintenance and breakdown of mutualism. I discuss how these ideas might apply to and be tested in ant-plant, fig-wasp and yucca-moth mutualisms.
181 citations
TL;DR: Fruit production continued to be a good predictor of primate biomass in the Neotropics, but primate species richness was best predicted by latitudinal gradients and plant species richness.
Abstract: Ecological models predict a positive correlation between fruit production and primate abundance in the Neotropics. To test this relationship, I compiled information on primate abundance and calculated different indexes of fruit production for 30 Neotropical sites. These indexes can be grouped in three categories: (1) Fruit production estimates based on fruit traps, (2) basal area of endozoochorous trees and (3) density of these trees. The first estimate was the best predictor of both primate biomass (r2=0.80) and species richness (r2=0.64). The advantage of using fruit trap estimates is that they take into account production rates (which is not the case for basal area or density estimates), while the advantage of using basal area over density estimates is that it includes some of the expected variation due to tree size. However, using both basal area and density indexes I found a positive correlation between the basal area index and primate biomass for frugivorous monkeys and small platyrhines, but there was no correlation for folivorous and seed predator primates. I also found a positive correlation between pitheciine biomass and the abundance of Eschweilera trees. The analyses gave little support to the importance of suggested keystone resources such as figs and palms. Finally, when including climatic, geographic and plant diversity variables, fruit production continued to be a good predictor of primate biomass in the Neotropics, but primate species richness was best predicted by latitudinal gradients and plant species richness.
172 citations
TL;DR: The total molecular evidence provided a better-resolved hypothesis than did separate analysis of individual partitions, and the PBS analysis indicates congruence among independent partitions for support of some internal nodes.
Abstract: A molecular phylogeny was reconstructed for 26 recognized genera of the Gymnophthalmidae using a total of 2379 bp of mitochondrial (12S, 16S and ND4) and nuclear (18S and c-mos) DNA sequences. We performed maximum parsimony (MP) and maximum likelihood (ML) analyses, and data partitions were analysed separately and in combination under MP. ML analyses were carried out only on the combined sequences for computational simplicity. Robustness for the recovered nodes was assessed with bootstrap and partitioned Bremer support (PBS) analyses. The total molecular evidence provided a better-resolved hypothesis than did separate analysis of individual partitions, and the PBS analysis indicates congruence among independent partitions for support of some internal nodes. Based on this hypothesis, a new classification for the family is proposed. Alopoglossus, the sister group of all the other Gymnophthalmidae was allocated to a new subfamily Alopoglossinae, and Rhachisaurus (a new genus for Anotosaura brachylepis) to the new Rhachisaurinae. Two tribes are recognized within the subfamily Gymnophthalminae: Heterodactylini and Gymnophthalmini, and two others within Cercosaurinae (Ecpleopini and Cercosaurini). Some ecological and evolutionary implications of the phylogenetic hypothesis are considered, including the independent occurrence of limb reduction, body elongation, and other characters associated with fossoriality.
170 citations
TL;DR: The recovery of the ectoparasitic-containing proctotrupomorphs (Chalcidoidea and, in some analyses, Ceraphronoidea) as apical lineages argues that these biologies are reversals.
Abstract: Simultaneous analysis of morphological and molecular characters from the 16S rDNA, 28S rDNA and cytochrome oxidase 1 genes was employed to resolve phylogenetic relationships among the apocritan (Insecta: Hymenoptera: Apocrita) wasps Parsimony analyses, employing a broad range of models, consistently recovered the Proctotrupomorpha as a natural group, the Megalyridae and Trigonalidae as sister groups, a clade comprising the Monomachidae, Diapriidae, and Maamingidae, the Vanhorniidae and Proctotrupidae as sister groups, the Proctotrupoidea as polyphyletic, and the Evaniomorpha as a grade (but including the Ichneumonoidea, Aculeata, and Stephanidae) The Proctotrupomorpha, containing virtually all of the wholly endoparasitic lineages, was consistently recovered as an apical clade, with the remaining groups forming a paraphyletic grade below them Although the relative placement of the groups forming this basal grade varied among analyses, the most commonly recovered arrangement is consistent with the ancestral biology being ectoparasitism of coleopteran, wood-boring larvae Furthermore, the recovery of the ectoparasitic-containing proctotrupomorphs (Chalcidoidea and, in some analyses, Ceraphronoidea) as apical lineages argues that these biologies are reversals
143 citations
TL;DR: Evaluating the sexual dimorphism of body proportion of more than 800 wild steppe tortoises in Uzbekistan found males were able to right themselves more quickly than females did in experimental tests, and a number of simple hypotheses can be tested on a wide range of chelonian species.
Abstract: Selective forces shape sexes differently, with male body proportions facing strong selection to enhance mate searching and male-to-male combat traits, and female fitness being influenced by the ability to assimilate large amounts of nutrients necessary for vitellogenesis (and/or gestation), and their ability to carry the eggs or embryos. We evaluated the sexual dimorphism of body proportion of more than 800 wild steppe tortoises ( Testudo horsfieldii ) in Uzbekistan. The thick, well-developed shell offers protection from predators but pronounced digging habits probably also constrain body shape (e.g. a shell that is dorso-ventrally flattened, although round from a dorsal view helps to penetrate into, and move within the soil). Thus, in this species, natural selection might favour a heavy and flat shell that is «closed» with small openings for appendages. In males, these environmental influences appear to be countered by sexual selection. Compared to females, they weigh less (absolutely and relative to shell dimensions), have longer legs, have shell structure allowing wider movements for their legs, and they walk faster. Males were also able to right themselves more quickly than females did in experimental tests. This quick righting ability is critical because intra-sexual combats frequently result in males being flipped onto their backs and becoming prone to hyperthermia or predation. Females are heavily built, with wide shells (relative to male shells), which may provide space for carrying eggs. From our results, a number of simple hypotheses can be tested on a wide range of chelonian species.
138 citations
TL;DR: Diet of unparasitized stickleback was examined, predicting that differences in dietary niche would influence relative parasitism, and showed that female stomach contents had increased frequency of pelagic items, the major habitat for the primary host of S. solidus whereas males exhibited increased Frequency of benthic items,the dominant habitat of C. truncatus and Bunodera.
Abstract: Males and females can differ in levels of parasitism and such differences may be mediated by the costs of sexual selection or by ecological differences between the genders. In threespine stickleback, Gasterosteus aculeatus, males exhibit paternal care and territorial nest defence and the costs of reproduction may be particularly high for males relative to females. We monitored levels of parasitism for 15 years in a population of stickleback infected by four different parasite species. Consistent with general predictions, overall parasite prevalence (total parasitism) was greater in males than in females. However, this excess did not occur for each species of parasite. Males had higher prevalence of a cestode Cyathocephalus truncatus and a trematode Bunodera sp. relative to females, while females had higher prevalence of a cestode Schistocephalus solidus and nematodes. This suggested ecological sources to differences in parasitism rather than reproductive costs and therefore we examined diet of unparasitized stickleback, predicting that differences in dietary niche would influence relative parasitism. This was partially confirmed and showed that female stomach contents had increased frequency of pelagic items, the major habitat for the primary host of S. solidus whereas males exhibited increased frequency of benthic items, the dominant habitat of C. truncatus and Bunodera. Temporal shifts in the extent and direction of differential parasitism among years between the sexes were associated with temporal shifts in dietary differences. Our results, combined with those in the literature, suggest that ecological differences between genders could be a more important component to patterns of parasitic infection in natural populations than currently appreciated.
134 citations
TL;DR: It is indicated that dramatically new feeding modes arose only a few times, that the most derived feeding modes likely arose in the Miocene, and that much of the known diversity of Conus that was generated during Miocene radiations has survived to the present.
Abstract: Specialized predators on polychaetes, fishes, hemichordates or other molluscs, members of the predominantly tropical gastropod genus Conus diversified rapidly during the Miocene to constitute the most species-rich modern marine genus. We used DNA sequence data from mitochondrial and nuclear loci of 76 Conus species to generate species-level phylogenetic hypotheses for this genus and then mapped known diets onto the phylogenies to elucidate the origins and evolutionary histories of different feeding specializations. The results indicate that dramatically new feeding modes arose only a few times, that the most derived feeding modes likely arose in the Miocene, and that much of the known diversity of Conus that was generated during Miocene radiations has survived to the present.
TL;DR: The pollination syndrome appears to be a generalized form of Batesian mimicry, in which similarity to rewarding plants determines reproductive success.
Abstract: We studied the pollination of Orchis boryi at five different locations on the Greek mainland. Orchis boryi is food deceptive and obligatorily insect pollinated. Primary pollinators were Apis mellifera and Bombus spp., which foraged on rewarding plant species nearby and visited O. boryi in between. To analyse floral colour similarity among rewarding plants and O. boryi as perceived by bees, a model of bee colour vision was employed. For each food plant an index was calculated that described the probability of a bee foraging on it to subsequently choose an orchid flower. This choice probability correlated to colour distance according to the model of bee colour vision, indicating that bees chose the deceptive orchid more frequently if they foraged on more similarly coloured species. At different sites different plant species served as models. Bees foraging on food plants from which a high choice rate to the orchid was observed visited the orchid less often after approaching it than other bees, which is likely to reflect avoidance learning. In general, the pollination syndrome appears to be a generalized form of Batesian mimicry, in which similarity to rewarding plants determines reproductive success. As expected by negative density-dependent selection, individual fruit set and pollinia export rate correlated negatively with orchid density, but were unaffected by food plant density, orchid frequency, individual variation of labellum colour, labellum size, or mouth width of the flowers.
TL;DR: The abundance, activity and species richness of arthropods, particularly of insect herbivores, were investigated in the upper canopy and understorey of a lowland rainforest at La Makande, Gabon and it was confirmed that the fauna of theupper canopy was different, diverse and very poorly known in comparison to that of theUnderstorey.
Abstract: The abundance, activity and species richness of arthropods, particularly of insect herbivores, were investigated in the upper canopy and understorey of a lowland rainforest at La Makande, Gabon. In total 14 161 arthropods were collected with beating, flight interception and sticky traps, from six canopy sites, during the day and at night, from mid-January to mid-March 1999. The effects of stratum were most important, representing between 40 and 70% of the explained variance in arthropod distribution. Site effects represented between 20 and 40% of the variance and emphasized the need for replication of sampling among canopy sites. Time effects (diel activity) explained a much lower percentage of variance (6–9%). The density and abundance of many arthropod taxa and species were significantly higher in the upper canopy than in the understorey. Arthropod activity was also higher during the day than at night. In particular, insect herbivores were 2.5 times more abundant and twice as speciose in the upper canopy than in the understorey, a probable response to the greater and more diverse food resources in the former stratum. Faunal overlap between the upper canopy and understorey was low. The most dissimilar herbivore communities foraged in the understorey at night and the upper canopy during the day. Further, a taxonomic study of a species-rich genus of herbivore collected there Agrilus , Coleoptera Buprestidae) confirmed that the fauna of the upper canopy was different, diverse and very poorly known in comparison to that of the understorey. Herbivore turnover between day and night was rather high in the upper canopy and no strong influx of insect herbivores from lower foliage to the upper canopy was detected at night. This suggests that insect herbivores of the upper canopy may be resident and well adapted to environmental conditions there.
TL;DR: This study represents one of the first conclusively documented examples of Bergmann's Rule in a tropical mammal and confirms that latitudinal clines in body size are not exclusively restricted to temperate zone homeotherms.
Abstract: Geographic variation in body size and sexual dimorphism of the short-nosed fruit bat (Cynopterus sphinx) was investigated in peninsular India. Bats were sampled at 12 localities along a 1200 km latitudinal transect that paralleled the eastern flanks of the Western Ghats. The geographic pattern of variation in external morphology of C. sphinx conforms to the predictions of Bergmann's Rule, as indicated by a steep, monotonic cline of increasing body size from south to north. This study represents one of the first conclusively documented examples of Bergmann's Rule in a tropical mammal and confirms that latitudinal clines in body size are not exclusively restricted to temperate zone homeotherms. Body size was indexed by a multivariate axis derived from principal components analysis of linear measurements that summarize body and wing dimensions. Additionally, length of forearm was used as a univariate index of structural size to examine geographic variation in a more inclusive sample of bats across the latitudinal transect. Multivariate and univariate size metrics were strongly and positively correlated with body mass, and exhibited highly concordant patterns of clinal variation. Stepwise multiple regression on climatological variables revealed that increasing size of male and female C. sphinx was associated with decreasing minimum temperature, increasing relative humidity, and increasing seasonality. Although patterns of geographic size variation were highly concordant between the sexes, C. sphinx also exhibited a latitudinal cline in the magnitude and direction of sexual size dimorphism. The size differential reversed direction across the latitudinal gradient, as males averaged larger in the north, and females averaged larger in the south. The degree of female-biased size dimorphism across the transect was negatively correlated with body size of both sexes. Canonical discriminant analysis revealed that male- and female-biased size dimorphism were based on contrasting sets of external characters. Available data on geographic variation in the degree of polygyny in C. sphinx suggests that sexual selection on male size may play a role in determining the geographic pattern of sexual size dimorphism.
TL;DR: The likelihood of genetic drift in natural populations of three endemic species of Lepanthes (Orchidaceae) from Puerto Rico is investigated to suggest restricted gene flow among populations in the range of one or less successful migrant per generation.
Abstract: Genetic drift can play an important role in population differentiation, particularly when effective population sizes are small and gene flow is limited Such conditions are suspected to be common in the species-rich Orchidaceae We investigated the likelihood of genetic drift in natural populations of three endemic species of Lepanthes (Orchidaceae) from Puerto Rico We estimated effective population size, Ne, using three ecologically based methods Two of the three estimates were based on variance in reproductive potential and the third was based on coalescence time All estimates of Ne were usually <40% of the standing population size, resulting in values of <20 individuals per population Based on starch gel electrophoresis of isozymes, Nm estimates suggest restricted gene flow among populations in the range of one or less successful migrant per generation Genetic differentiation among populations is expected under such conditions from random genetic drift Indeed we observed high genetic differentiation among populations (L rubripetala, FST,GST , θ; 0248, 0266, 0293 L rupestris, 0148, 0169, 0138 L eltoroensis, 0251, 0219, 0218, respectively) Genetic drift is likely to be important for population differentiation in Lepanthes as a result of small effective population sizes and restricted gene flow
TL;DR: The results suggest that the differences have a genetic basis, and they are likely to indicate adaptation to local environmental conditions in the native habitat of the trout.
Abstract: The trout (Salmo trutta) has been divided into three forms: sea-run trout, lake-run brown trout, and resident brown trout. They differ in their living environment, migratory behaviour, growth and appearance. As local trout populations are often isolated, and gene flow between them is minimal, differentiation between populations can be expected. The morphology of 1-year-old trout from ten populations representing all three forms was studied in a common-garden experiment. The fish were reared under similar environmental conditions, and 20 morphometric characters were measured from each individual fish. Marked morphological differentiation was found, and differences between populations were greater than differences between forms. The results suggest that the differences have a genetic basis, and they are likely to indicate adaptation to local environmental conditions in the native habitat of the trout.
TL;DR: Intraspecific variation and intersexual correlation in secondary sexual characters of three diving-beetles (Coleoptera: Dytiscidae) are studied.
Abstract: Intraspecific variation and intersexual correlation in secondary sexual characters of three diving-beetles (Coleoptera: Dytiscidae)
TL;DR: Allozyme analysis of Erebia medusa over large regions of Europe revealed a significant population differentiation and it is likely for the western lineage that its ice-age distribution showed at least one disjunction in late Wurm with the consequence of further genetic differentiation.
Abstract: Allozyme analysis of Erebia medusa over large regions of Europe revealed a significant population differentiation (FST: 0.149±0.016). A UPGMA-analysis showed a division into four major lineages with mean inter-group genetic distances ranging from 0.051 (±0.010) to 0.117 (±0.024). An AMOVA revealed that rather more than two-thirds of the variance between samples was being between these lineages and less than one-third within lineages. An eastern group included the samples from the Czech Republic, Slovakia and north-eastern Hungary. This genetic lineage expressed significantly higher genetic diversity than the other three. A second lineage was formed by the samples from France and Germany. The two samples from western Hungary represent a third delimited lineage and the sample from northern Italy a fourth. We suppose that this genetic differentiation took place during the last ice-age in four disjunct refugia. The genetically more diverse eastern genetic lineage might have evolved in a relatively large refugium in south-eastern Europe. We assume that the other three lineages developed in relatively small relict areas around the Alps. It is likely for the western lineage that its ice-age distribution showed at least one disjunction in late Wurm with the consequence of further genetic differentiation. Most probably, the eastern lineage colonized postglacial Central Europe using two alternative routes: one north and one south of the Carpathians. Up to now, neither similar glacial refugia, nor comparable secondary disjunctions in late Wurm, are reported for any other animal or plant species.
TL;DR: Small-scale vegetational patterns of Georgian lowland and montane forests and wetlands are documented by species per vegetation unit, function of species in particular vegetation units and vegetational sketches, which find four different niching strategies for Tertiary relict plant taxa in western Georgia.
Abstract: Small-scale vegetational patterns of Georgian lowland and montane forests and wetlands are documented by species per vegetation unit, function of species in particular vegetation units and vegetational sketches. The humid warm-temperate climate of western Georgia contributes to a different spatial pattern than known for most of Europe. One characteristic feature of western Georgian relict vegetation is the co-occurrence of «Mediterranean», «Submediterranean», temperate, and Tertiary relict species, as well as of species normally confined to either zonal or azonal vegetation, in the same or closely related vegetation units. The extant distribution of Tertiary relict taxa strongly depends on how they are niching into changing environments. Niching strategies are assumed crucial for extinction or survival in times of rapid climatic/environmental changes. For Tertiary relict plant taxa in western Georgia we found four different niching strategies which also hold true of other northern hemispheric Tertiary relict plant taxa. Some amphibians and reptiles display similar distribution patterns and niching strategies as do relict plant taxa. A number of relict taxa in the warm humid regions of western Georgia occupy niches in swamp forests which might represent «primeval» environments of species which are at present also elements of meso-Mediterranean vegetation and of thermophilous forest edges and hedges in Central Europe.
TL;DR: Two independent methods are used to predict the global species richness of the subfamilies of the parasitic wasp family Braconidae, and there is a significant correlation between the proportions of undescribed species predicted by each method.
Abstract: The need to estimate the magnitude of undescribed species richness arises from the limited resources available to the description and conservation of biodiversity, the continuous loss of diversity that we are currently experiencing, and the sheer scale of the task of accurate measurement. Several estimation methods have previously been described and discussed in some detail, but the reliability of these methods is difficult to assess. In this study, we use two independent methods to predict the global species richness of the subfamilies of the parasitic wasp family Braconidae. The first is to extrapolate from the decreasing rate of species descriptions to the point at which this rate reaches zero. The second method uses the geographical distribution of species in two well-studied taxa (butterflies and mammals) to extrapolate from our knowledge of braconid diversity in the Palaearctic. For the subfamilies which currently contain at least 50 species, there is a significant correlation between the proportions of undescribed species predicted by each method. Each method predicts an average increase of between 100% and 200% for the Braconidae as a whole. Applying the figures we obtain to the class Insecta yields an estimate of 2.05–3.4 million global insect species.
TL;DR: It is more probable that cichlids arose less than 65 million years ago, in the Early Tertiary, and crossed marine waters to attain their current distribution.
Abstract: The family Cichlidae is a large group of tropical fishes in the order Perciformes, with an estimated number of living species exceeding 1400. The modern distribution of the family Cichlidae is predominantly in fresh waters of Central and South America, Africa, Madagascar, India and the Middle East, with fossil members known from Africa, Saudi Arabia, the Levant, Europe, South America and Haiti. Many authors have referred to the distribution as being Gondwanan and have postulated that cichlids originated over 130 million years ago, in the Early Cretaceous. However, the suggested evidence for an Early Cretaceous origin of cichlids is equally or more compatible with a much younger age of origin. Based on the biology and distribution of modern and fossil cichlids, it is more probable that they arose less than 65 million years ago, in the Early Tertiary, and crossed marine waters to attain their current distribution.
TL;DR: In this article, the authors compared body, head and limb shape between four populations of Urosaurus ornatus living in structurally distinct habitats (cliffs, rocks, trees and boulders).
Abstract: Recent ecomorphological studies have shown that the predicted correlations between morphology and ecology on broad taxonomic levels are often obscured when comparing more closely related groups. Among species, comparisons of lizards often indicate very little support for adaptive radiations into novel habitats. As few population level studies have been performed, we compared body, head and limb shape between four populations of Urosaurus ornatus living in structurally distinct habitats (cliffs, rocks, trees and boulders). Surprisingly, clear correlations between habitat use and body shape among populations were found, most of which were in good accordance with a priori biomechanical predictions (e.g. flat body and head for extreme climbers; long distal hindlimb segments for jumpers and runners; narrow body and long tail for tree dwelling lizards). This indicates that populations of Urosaurus ornatus are seemingly «adapted» to the habitat they live in. However, quantification of performance and behaviour are needed to determine the adaptive nature of these observations.
TL;DR: Bayesian estimation of divergence times indicates that the divergence between the Australian and the South American Araucaria -feeding taxa occurred at the very latest in the Cretaceous/Paleocene border and that the age of the first Scolytinae–Araucaria association would then be during the later stages of the Late Cretsaceous, while other known beetle/ARAucaria associations are Jurassic.
Abstract: Studies of a variety of phenomena, ranging from rates of molecular substitution to rates of diversification, draw on estimates of geological age. Studies incorporating estimates of timing from fossils or other geological evidence are largely of relatively young, Tertiary divergences, to which older systems may provide useful comparisons. One apparently old assemblage comprises the beetle groups associated with the ancient genus Araucaria that share comparable, ostensibly Gondwanan distributions with their host. Our previous studies suggested a possibly Cretaceous age for Araucaria associations in bark beetles. However, the absence of confirmed bark beetle fossils earlier than the Tertiary has been taken as evidence of Cretaceous absence, and their confirmed phylogenetic position within the primitively angiosperm-feeding weevil family rules out pre-angiosperm, Jurassic origins. Nevertheless, an early shift from angiosperms to Araucaria seemed plausible in the light of Araucaria fossil history which spans the Mesozoic since the Jurassic. To resolve the phylogenetic affinities and to estimate divergence times of the Australian and South American bark beetle genera affiliated with Araucaria we analysed DNA sequences of nuclear and mitochondrial genes: protein coding elongation factor alpha, enolase and cytochrome oxidase I. The most parsimonious reconstruction of the host relationships of Tomicini from the combined dataset corroborates the ancestral association with the genus Araucaria of both South American and Australian Tomicini. Bayesian estimation of divergence times indicates that the divergence between the Australian and the South American Araucaria -feeding taxa occurred at the very latest in the Cretaceous/Paleocene border and that the age of the first Scolytinae–Araucaria association would then be during the later stages of the Late Cretaceous, while other known beetle/Araucaria associations are Jurassic.
TL;DR: The results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.
Abstract: In species with reduced locomotory abilities, camouflage seems to be far more important than other behavioural tactics (e.g. running) to elude predatory attacks. In this study, we examined the effects of camouflage on escape decisions in the common chameleon Chamaeleo chamaeleon. The effectiveness of camouflage was assessed by the ability of humans to detect different sized chameleons placed on different backgrounds (vegetation of high and low density, defined here as open and dense bushes), both in the field and in photographs. Escape behaviour was analysed by simulating a predator attack (in our case, approach by a human). As expected, the probability of detection by a potential predator was size- and background dependent. In the field, detection time (but not distance) was significantly higher for chameleons of a given size perched on dense (Myoporum) than open (Retama) bushes. When using photographs, the probability of detection was higher for large (adult) chameleons perched on open (Retama or Nerium) bushes and lower for hatchlings perched on dense (Myoporum or Cupressus) bushes. Conspicuousness greatly influenced the escape tactics of individuals. Chameleons perched on more protected Myoporum allowed closest approach distances than those perched on less protectedRetama . In general, antipredatory responses (defined here as «first movement», «fleeing», «mouth opening» or «free falling») occurred significantly earlier in the trial sequence in chameleons perched on clear Retama than those perched in Myoporum. Two antipredatory responses were size-dependent: juveniles and adults exhibited «mouth opening» more frequently than hatchlings whereas «free falling» was more frequently recorded for hatchlings. Our results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.
TL;DR: Data do not support the generalization that water availability during embryogenesis is more important than temperature in determining the phenotypes of hatchling reptiles, and suggest that hatchling lizards react less plastically to variation in moisture levels than they do to thermal conditions.
Abstract: Recent studies have shown that incubation temperatures can profoundly affect the phenotypes of hatchling lizards, but the effects of hydric incubation environments remain controversial. We examined incubation-induced phenotypic variation in Bassiana duperreyi (Gray, 1938; Sauria: Scincidae), an oviparous montane lizard from south-eastern Australia. We incubated eggs from this species in four laboratory treatments, mimicking cool and moist, cool and dry, warm and moist, and warm and dry natural nest-sites, and assessed several morphological and behavioural traits of lizards after hatching. Incubation temperature influenced a lizard's hatching success, incubation period, tail length and antipredator behaviour, whereas variation in hydric conditions did not engender significant phenotypic variation for most traits. However, moisture affected incubation period slightly differently in males and females, and for a given snout-vent length moisture interacted weakly with temperature to affect lizard body mass. Although incubation conditions can substantially affect phenotypic variation among hatchling lizards, the absence of strong hydric effects suggests that hatchling lizards react less plastically to variation in moisture levels than they do to thermal conditions. Thus, our data do not support the generalization that water availability during embryogenesis is more important than temperature in determining the phenotypes of hatchling reptiles.
TL;DR: Galapagos colonization by an eastern Pacific biota between late Cretaceous and mid-Tertiary has significant implications for understanding the tempo and mode for both the origins of island biota and general models of evolutionary differentiation.
Abstract: Biogeographic tracks are mapped for Galapagos endemics representing 25 plant and animal taxa and including organisms with good and poor means of dispersal. These patterns confirm standard biogeographic tracks linking Galapagos with Central America, western North and South America, the Caribbean, Asia and Australasia. Discovery of the Galapagos Gore in the 1970s corroborates the biogeographic prediction for a major tectonic centre associated with the Galapagos. The biogeographic model developed by Croizat in 1958 of Galapagos colonization involving an ancestral biota inhabiting eastern Pacific geosynclinal forelands is congruent with plate tectonic models supporting a Pacific island arc origin for western American terranes. American relatives of Galapagos endemics may have originated within an eastern Pacific paleogeography rather than representing centres of origin for dispersal to the Galapagos. Galapagos colonization by an eastern Pacific biota between late Cretaceous and mid-Tertiary has significant implications for understanding the tempo and mode for both the origins of island biota and general models of evolutionary differentiation. Popular assertions that overwater dispersal represents the only viable origin for the entire Galapagos biota is no longer biogeographically or geologically tenable.
TL;DR: Phylogenetic analysis of mitochondrial DNA sequence data using maximum parsimony, minimum evolution (of log-determinant distances), and maximum-likelihood optimality criteria provided a robust estimate of Draco phylogenetic relationships.
Abstract: Phylogenetic analysis of mitochondrial DNA sequence data using maximum parsimony, minimum evolution (of log-determinant distances), and maximum-likelihood optimality criteria provided a robust estimate of Draco phylogenetic relationships. Although the analyses based on alternative optimality criteria were not entirely congruent, nonparametric bootstrap analyses identified many well-supported clades that were common to the analyses under the three altrenative criteria. Relationships within the major clades are generally well resolved and strongly supported, although this is not the case for the Philippinevolans subclade. The hypothesis that a clade composed primarily of Philippine species represents a rapid radiation could not be rejected. A revised taxonomy for Draco is provided.
TL;DR: In this paper, the authors show that exposure to warmer-than-usual temperatures for 2 weeks during the 9- to 16-week incubation period doubled hatching success, and significantly modified hatchling phenotypes (hatching dates, offspring size and locomotor performance).
Abstract: Can short-term stochastic variation in local weather conditions modify the thermal conditions inside lizard nests, and thus (potentially) the developmental rates, hatching success, and phenotypic traits of hatchlings from these nests? This hypothesis requires that (i) natural nests are poorly buffered thermally, such that ambient regimes affect temperatures inside the nest, and (ii) short-term thermal variations modify attributes of the offspring. Field data on natural nests of the sub-alpine skink Bassiana duperreyi confirm the existence of this first effect, and laboratory experiments substantiate the latter. Exposure to warmer-than-usual temperatures for 2 weeks during the 9- to 16-week incubation period doubled hatching success, and significantly modified hatchling phenotypes (hatching dates, offspring size and locomotor performance). The proportion of development completed prior to this exposure influenced the degree of response. Exposure to a brief «window» of higher-than-usual temperatures soon after oviposition had more effect on hatching time, egg survival and hatchling phenotypes than if the exposure occurred later in development. Thus, minor variations in weather conditions during incubation may have substantial effects on reptile populations.
TL;DR: Evidence is presented to show how geological, ecological, and physiological factors could have interacted to select for a short wavelength-reflective dewlap from a long wavelength- reflective precursor following the colonization of Grand Cayman from Jamaica by A. grahami between 2 and 3 Mya.
Abstract: Data from a diversity of sources are consistent with the hypothesis that the Grand Cayman anole, Anolis conspersus, is descended directly from Anolis grahami of Jamaica. Although the two species have remained morphologically similar, coloration in A. conspersus has changed considerably from that of its ancestor. The most dramatic difference is seen in dewlap colour, where A. conspersus has evolved a blue and highly UV-reflective dewlap from the ancestral orange-and-yellow colour state. In addition, variation in normal (non-metachrosis) dorsum coloration in A. grahami populations is limited to shades of green (olive, emerald, teal), whereas in A. conspersus dorsum coloration varies from green to blue and to brown. This increased colour variation occurs despite Grand Cayman being a small, relatively featureless island only 35 km in length. Results of this study suggest that ambient light differences associated with precipitation-related vegetation structure may have played an important role in the evolution of A. conspersus body colour variation. Evidence is presented to show how geological, ecological, and physiological factors could have interacted to select for a short wavelength-reflective dewlap from a long wavelength-reflective precursor following the colonization of Grand Cayman from Jamaica by A. grahami between 2 and 3 Mya.
TL;DR: It is concluded that phylogeographies of open forest frogs are complex and more difficult to predict than for rainforest taxa, mainly due to an absence of palaeomodels for historical distributions of non-rainforest habitats.
Abstract: We investigated the phylogeography of two closely related Australian frog species from open forest habitats, Limnodynastes tasmaniensis and L. peronii, using mitochondrial ND4 sequence data. Comparison of our results with previous work on Litoria fallax allowed us to test the generality of phylogeographic patterns among non-rainforest anurans along the east coast of Australia. In general, there was no strong evidence for congruence between overall patterns of genetic structure in the three species. However, phylogenetic breaks congruent with the position of the Burdekin Gap were detected at some level in all species. As previously noted for closed forest taxa, this area of dry habitat appears to have been an important influence on the evolution of several open forest taxa. There were broad geographic similarities in the phylogenetic structuring of southern populations of L. peronii and L. tasmaniensis. Contrarily, although the McPherson Range has previously been noted to coincide geographically with a major mtDNA phylogenetic break in Litoria fallax this pattern is not apparent in L. peronii or L. tasmaniensis. It appears that major phylogeographic splits within L. peronii and L. tasmaniensis may predate the Quaternary. We conclude that phylogeographies of open forest frogs are complex and more difficult to predict than for rainforest taxa, mainly due to an absence of palaeomodels for historical distributions of non-rainforest habitats.