Stratified activity: Vertical partitioning of the diel cycle by rainforest mammals in Borneo

Animal activity is driven by the environmental conditions and physical structure of a habitat, and the need to interact with, or avoid, other animals. Knowledge of the proportion of the 24-hour cycle spent active (activity level), and the time/s of day in which activity is concentrated (activity pattern), informs our understanding of species' ecology and community dynamics. In multidimensional habitats such as tropical rainforests, arboreal (canopy-dwelling) taxa comprise up to three-quarters of vertebrate assemblages; yet, wildlife surveys are typically limited to ground level. Terrestrial-only sampling can result in activity metrics that do not take account of species' full use of horizontal and vertical habitat space. We paired ground- and canopy-level camera traps to characterize mammal activity across vertical strata in Borneo. Additionally, we sampled unlogged and recovering-logged rainforest to evaluate whether this activity was impacted by logging. Activity across vertical strata varied substantially among 37 species. Arboreal mammals were predominantly nocturnal or diurnal but never cathemeral, terrestrial mammals were mostly nocturnal or cathemeral, and semi-arboreal mammals appeared to fill the temporal niches under-utilized by other groups. Differences in activity between unlogged and recovering-logged forest were minimal, with 92% of species found in both forest types retaining the same activity pattern. Our study demonstrates that the inclusion of canopy-based sampling provides much greater insights into overall rainforest mammal activity than terrestrial sampling alone. Our results suggest that the varying opportunities and constraints of each stratum act in concert to influence the diel patterns of tropical mammals. Abstract in Malay is available with online material.     

Can relaxed time constraints on sperm production eliminate protandry in an ectotherm?

In most temperate-zone reptiles, as in many other ectothermic taxa, males emerge from periods of inactivity (e.g. hibernation) before females, a pattern referred to as protandry. In the large body of theory depicting its evolution it is assumed that as selection pressures on females moderate female emergence time, net sexual selection on males shifts male emergence time accordingly. This is because early-emerging males might (i) benefit from advantages in behavioural interactions (e.g. obtain more matings, better territories, or a higher social status), or (ii) produce and mature more spermatozoa before the mating season. These putative advantages of early emergence occur simultaneously in most temperate-zone reptile species, because sperm production and copulations occur soon after emergence from winter inactivity. Thus, it is difficult to distinguish between the two hypotheses. To do so would require a system in which behavioural interactions occur at one time of year and sperm production at another. The southern snow skink ( Niveoscincus microlepidotum ) provides such an example; adult males fight with each other immediately after emerging from hibernation, but examination of the testes and epididymes of males throughout the year show that males do not produce spermatozoa until around 3 months later. Thus, the 'behavioural interactions' hypothesis predicts protandry in snow skinks, whereas the 'sperm production' hypothesis predicts synchronous spring emergence in males and females. Our field data, collected over 5 years, show that emergence dates in spring are the same for male and female skinks. Hence, when the selection pressure for rapid sperm production is relaxed, we no longer see the protandric emergence pattern characteristic of most temperate-zone reptiles.     

Bergmann's idiosyncratic rule: a role for fecundity selection?

The negative relationship between temperature and geographical variation in body size, or Bergmann's rule, is among the most thoroughly studied ecogeographical rules, yet the pattern and process underlying it remain controversial. Bergmann's original observations were of body size clines among endotherms, but in the last 50 years there has been increasing recognition that both Bergmann's rule and its reverse occur in many ectotherm taxa. A new study of syngnathid fish by Wilson (2009 ) in this issue of Molecular Ecology sheds light on intriguing alternative mechanisms that may explain variation in the direction of body size clines across taxa. Wilson shows that Bergmann's rule is found in pipefish of the genus Syngnathus , but not in seahorses of the genus Hippocampus . His results suggest that polygamy in pipefish allows fecundity selection to favour large size at low temperatures, compensating for increases in brooding time.     

Age rank/clade rank metrics--sampling,taxonomy, and the meaning of "stratigraphic consistency"

Paleontologists frequently contrast clade rank (i.e., nodal or patristic distance from the base of a cladogram) with age rank (i.e., relative first known appearances of the analyzed taxa) to measure the degree of congruence between the estimated phylogeny and the fossil record. Although some potential biases of these methods have been examined (e.g., the effect of tree imbalance), other properties of age rank/clade rank (ARCR) comparisons have not been studied in detail. A basic premise of ARCR metrics is that outgroup taxa diverged earlier than ingroups and thus should first appear in older strata. For example, given phylogeny (A,(B,C)), then taxon A should be sampled before either taxon B or taxon C. We examine this premise in the context of (1) phylogenetic theory, (2) taxonomic practice, (3) sampling intensity (R), and (4) factors other than sampling intensity (including cladogram accuracy). Simulations combining clade evolution and sampling over time indicate a poor relationship between ARCR metrics and R when all taxa are apomorphy-based monophyletic groups. However, a good relationship exists when taxa are either stem-based monophyletic groups or if workers include taxa without a priori decisions about monophyly or paraphyly. These results are not surprising because cladograms predict the order in which lineages diverged (which applies to stem-based monophyletic taxa) and the order in which morphologic grades appeared (which applies to paraphyletic taxa relative to derived monophyletic groups). Other factors that increase ARCR metrics when the average R stays the same include high temporal variation in R, budding instead of bifurcating speciation patterns, low extinction rates, cladogram inaccuracy, and (to a much lesser extent) large clade size. These results suggest several plausible explanations for patterned differences in ARCR metrics among clades, thereby compromising their validity as measures of the quality of the fossil record.     

Defining and measuring trophic role similarity in food webs using regular equivalence

We present a graph theoretic model of analysing food web structure called regular equivalence. Regular equivalence is a method for partitioning the species in a food web into "isotrophic classes" that play the same structural roles, even if they are not directly consuming the same prey or if they do not share the same predators. We contrast regular equivalence models, in which two species are members of the same trophic group if they have trophic links to the same set of other trophic groups, with structural equivalence models, in which species are equivalent if they are connected to the exact same other species. Here, the regular equivalence approach is applied to two published food webs: (1) a topological web (Malaysian pitcher plant insect food web) and (2) a carbon-flow web (St. Marks, Florida seagrass ecosystem food web). Regular equivalence produced a more satisfactory set of classes than did the structural approach, grouping basal taxa with other basal taxa and not with top predators. Regular equivalence models provide a way to mathematically formalize trophic position, trophic group and trophic niche. These models are part of a family of models that includes structural models used extensively by ecologists now. Regular equivalence models uncover similarities in trophic roles at a higher level of organization than do the structural models. The approach outlined is useful for measuring the trophic roles of species in food web models, measuring similarity in trophic relations of two or more species, comparing food webs over time and across geographic regions, and aggregating taxa into trophic groups that reduce the complexity of ecosystem feeding relations without obscuring network relationships. In addition, we hope the approach will prove useful in predicting the outcome of predator-prey interactions in experimental studies.     

The ecologry of anchihaline caves

The dark, mostly brackish, aquatic habitats along the coasts are inhabited by a number of phylogenetically and/or biogeographically interesting animal taxa, whose ecology is poorly known. We are especially ignorant about the nature of the deoxygenated strata that occur in most of these habitats. Are these strata anoxic or only dysoxic? And how are their inhabitants adapted to low oxygen tensions?     

On biotas and their names

Biogeographers working under different approaches have proposed several terms to refer to biotas, e.g. the flora and fauna of a region, and to name subsets of taxa within such biotas. It is not clear whether they refer exactly to the same entities and which is the most adequate term to refer to them. Ten concepts refer to the set of taxa that inhabit an area at a single temporal plane (concrete biota, chronofauna, area of endemism, nuclear area, phytocorion, centre of endemism, generalized track, biogeographical assemblage, taxonomic assemblage, and species assemblage), whereas another nine concepts refer to subsets of taxa within a biota (biotic element, historical source, historical component, faunal element, cenocron, dispersal pattern, distributional pattern, lineage, and historical biota). Three concepts can be ascribed to both groups, depending on the author considered (horofauna, chorotype and biotic component). I propose to use the terms ‘biota’ and ‘cenocron’ as general terms, within a framework of integrative pluralism. Biotas can be considered individuals, for which the terms area of endemism, generalized track or chorotype can be preferred for specific analyses. Cenocrons incorporate a temporal dimension when implying explicitly or implicitly a different time of their incorporation to the biota.     

Postembryonic development of the cervicothoracic muscles of Euborellia annulipes (Lucas) (Dermaptera: Labiduridae)

The cervicothoracic muscles of nymphal and adult Euborellia annulipes (Lucas) are described, the former for the first time. In the adult, eight new muscles are identified, while the nymphs possess a further seven muscles that disappear at maturation or before. Otherwise the same muscles occur in nymphs as in adults, though some nymphal muscles are less clearly separated from one another than their adult homologs. The attachment sites of certain muscles show a number of slight differences between nymphs and adults. The work emphasizes the necessity of taking the immature musculature into account in assessing the muscular pattern represented in an insect order.     

Understorey versus canopy: patterns of vertical stratification and diversity among Lepidoptera in a Bornean rain forest

We studied the vertical distribution of Lepidoptera from a canopy walkway within a dipterocarp rain forest at Kinabalu Park (Borneo) using three different methods: (1) Bait traps to survey fruit-feeding nymphalid butterflies, (2) standardized counts for predominantly flower-visiting butterflies and their potential predators, aerial-hawking birds, and (3) attraction by blacklight for hawk- and tiger moths. There was a distinct decrease in the abundance of fruit-feeding nymphalids towards the canopy, probably due to a reduced and less predictable availability of rotting fruits in higher strata. These constraints might also be responsible for a higher abundance variation in the canopy, and a significant shift in size from larger species in the understorey to smaller ones in the canopy. Changes of microclimate and the conspicuous increase of insectivorous aerial-hawking birds from ground to canopy layer may be responsible for the prominent change in species composition of fruit-feeding nymphalids between 20 and 30 m. Nectar-feeding Lepidoptera showed a reversed abundance pattern. One main factor contributing to the much higher abundance of flower-visiting butterflies and moth taxa in the canopy, such as Sphingidae and some Arctiinae, might be the increase of nectar resources available in upper vegetation layers. A distinctly higher diversity in hawkmoths was also found in the canopy. A higher abundance of insectivorous aerial-hawking birds in the canopy might contribute to the shift in body design of fruit-feeding nymphalids from more slender bodies at lower vegetation layers to stouter ones (i.e. species which are stronger on the wing) in the canopy. Larval resources could play an additional role in specialisation on but a small part of the vertical gradient. This may explain stratification pattern of the nymphalid subfamilies Morphinae and Satyrinae. Monocotyledoneous larval food plants of both taxa, whose flight activity is largely restricted to the understorey, occur mostly in lower vegetation layers. Our observations on a wide taxonomic and ecological range of butterflies and moths indicate that tropical forest canopies hold a distinct and unique Lepidoptera fauna, whose species richness and abundance patterns differ from lower strata. However, the notion of tropical forest canopies as peaks of terrestrial diversity does not hold uniformly for all taxa or guilds.     

Linnean ranks,temporal banding,and time‐clipping: why not slaughter the sacred cow?

In a recent study, Avise & Liu (2011) (Biological Journal of the Linnean Society 102: 707–714) presented evidence indicating that Linnean ranks are not temporally standardized (i.e. taxa of the same rank differ greatly in age). This is one more argument that ranks veil rather than convey biological comparability. The authors also discuss recent suggestions as to how these shortcomings should be overcome, in particular temporal banding (by which the same rank is assigned to taxa of the same geological age) and time‐clipping (adding a code to each taxon denoting the geological episode when it originated). In this short comment, it is argued that both temporal banding and time‐clipping may be deleterious in taxonomic practice and that the abandonment of the Linnean ranks is long overdue. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 732–734.     

Functional morphology of synostosial articulations in the crinoid column

The rarest articulation found in the crinoid column is the synostosis, in which adjacent articular facets are essentially planar. 'Synostoses' in the columns of post-Palaeozoic isocrinids are more correctly termed cryptosymplexies. comprising symplectial articulations which have become infilled by secondary calcite. Cryptosymplexial joints are totally inflexible and are the preferred sites of stem autotomy. Synostoses sensu stricto appear to have been limited to early Palaeozoic taxa, but this form of articulation was soon succeeded by the symplexy. Synostoses were probably commonest in meric columns which evolved from hohlwurzels and in which the main flexibility was along meric sutures, rather than between columnals. With the evolution of the holomeric columnal. a more flexible articulation between columnals was a functional necessity in order that the stem did not develop into a stiffened rod. The solution was the evolution of the symplexy. *** Crinoids, columnals. synostosis, functional morphology evolution.     

Late Ordovician and early Silurian Proetida (Trilobita) from north-western and central Europe

Species belonging to genera of three families of the Proetida (Proetidae, Rorringtoniidae and Toernquistiidae) are described from the upper Ashgill of southern Sweden, and the same or related species noted from the adjacent parts of northern and central Europe. Proetidae are represented by Paraproetus brevifrons (Angelin), Ogmocnemis irregularis Kielan, Ogmocnemis jaanussoni sp. nov. and Parvigena putealis sp. nov.; it is argued that all belong to the Cornuproetinae, not Tropidocoryphinae where they were previously classified. Ogmocnemis is resurrected for some Upper Ordovician species included previously in Decoroproetus . The rorringtoniid genera Rorringtonia and Madygenia are recognised for the first time in southern Sweden, and it is argued that these are probably closely related, and both are included in the same family; both are recorded for the first time from Silurian (Llandovery) strata. Zetaproetus is claimed to be a junior subjective synonym of Rorringtonia. Solariproetus , first described from north-west China, is assigned to the Toernquistiidae as a late, derived member, and S. prosthemesos sp. nov. is described from late Rawtheyan strata in the Holy Cross Mountains, Skåne and the English Lake District. Comments are given on the stratigraphical and palaeogeographical distribution of these taxa.     

庭藤种综内分类群间变异式样的相关性

在种子植物中,种内的分化类型之呈连续的数量性状变异式样者屡见不鲜。毛叶石楠Photinia villosa(Thunb.)DC^[1]、短葶山麦冬Liri-ope muscari (Decne.)Bailey^[2]和胡枝子Lespedeza bicolor Turcz.^[3]就是很好的例证。     

Iterative evolution of Middle Jurassic ammonite faunas

The phenomenon of iterative evolution of homeomorphs in identical temporal sequences is exhibited by Aalenian and Bajocian ammonite faunas in the south German depositional basin. Within each evolutionary cycle, inflated, evolute, and ornamented shells with complex suture lines are successively replaced with discoidal, involute, smooth shells with simpler sutures. Three distinct and identical cycles of morphological change occur, and involve ammonites belonging to four different familial/subfamilial groups: the Leioceratinae, Graphoceratinae, Hammatoceratidae, and Sonniniidae. Geometric and statistical analyses of morphological change within each of these higher taxa reveal remarkable iteration in both the pattern and proportion of change with time. The iterative morphological cycles were not driven by orthogenesis or anagenetic transformation within lineages, as has been previously suggested. A clear correlation exists between the successive ammonite faunas and repeated cyclical changes in the physical marine environment of the depositional basin. D Ammonoidea, Aalenian, Bajocian, south Germany, iterative evolution.     

The structure of hepadnaviral core antigens. Identification of free thiols and determination of the disulfide bonding pattern.

A set of wild-type and mutant human, woodchuck, and duck hepatitis viral core proteins have been prepared and used to study the free thiol groups and the disulfide bonding pattern present within the core particle. Human (HBcAg) and woodchuck (WHcAg) core proteins contain 4 cysteine residues, whereas duck (DHcAg) core protein contains a single cysteine residue. Each of the cysteines of HBcAg has been eliminated, either singly or in combinations, by a two-step mutagenesis procedure. All of the proteins were shown to have very similar physical and immunochemical properties. All assemble into essentially identical core particle structures. Therefore disulfide bonds are not essential for core particle formation. No intra-chain disulfide bonds occur. Cys107 is a free thiol buried within the particle structure, whereas Cys48 is present partly as a free sulfhydryl which is exposed at the surface of the particle. Cys61 is always and Cys48 is partly involved in interchain disulfide bonds with the identical residues of another monomer, whereas Cys183 is always involved in a disulfide bond with the Cys183 of a different monomer. WHcAg has the same pattern of bonding, whereas DHcAg lacks any disulfide bonds, and the single free sulfhydryl, Cys153 which is equivalent to Cys107 of HBcAg, is buried.     

Wood‐Associated Macroinvertebrate Fauna in Central European Streams

An overview of macroinvertebrates associated with wood debris is given, with the main focus on Central European fauna. In general, three categories of macroinvertebrate wood relations are distinguished: taxa frequently associated with wood but not xylophagous, facultative xylophagous taxa and obligate xylophagous taxa. The adaptations in the life history, ethology and physiology of species representing these three groups are reviewed. From literature and our own investigations, 15 taxa inhabiting Central European freshwater ecosystems are known to be obligate xylophagous, 22 taxa are facultatively xylophagous. From field observations another 41 taxa presumably feed on wood although no gut content analyses and laboratory experiments have yet been carried out. From 25 taxa other forms of close association to CWD are known (feeding on epixylic biofilm, use as a refuge, or as an attachment point). Possible pathways of xylophagy evolution are discussed and unresolved aspects of aquatic invertebrate wood relations are listed.     

DEVELOPMENT AND DIVERSIFICATION OF TRUNK PLATES OF THE LOWER CAMBRIAN LOBOPODIANS

Abstract:  Isolated lobopodian plates are reported from Early Cambrian strata at five localities in southern China. A wide variety of morphologies is represented, reflecting a considerable diversification within the phylum at this time. The new taxon Microdictyon jinshaense is erected and new observations are recorded on established taxa, based on examination of more than 600 well-preserved plates; irregular patterns of node distribution and the presence of large spines are documented on some taxa for the first time. Rare specimens in which two plates are conjoined, with a larger plate underlying a smaller one, are interpreted as showing a new sclerite emerging underneath its predecessor, which has not yet been moulted. These specimens confirm the process of ecdysis in the lobopodians and contribute to a fuller understanding of the ontogeny of these organisms. A functional hypothesis that suggests that the plates were complex visual structures is refuted; it is possible that they were sites of muscle attachment, but a protective role is regarded as more plausible.     

Billingen (Lower Arenig/Lower Ordovician) acritarchs from the East European Platform and their palaeobiogeographic significance

Billingen (Lower Arenig/Lower Ordovician) sediments of the St. Petersburg region, northwest Russia and the Leba area, northern Poland of the East European Craton yield acritarch assemblages, which are largely homogenous though displaying minor compositional differences that probably reflect a gradient from inner to outer shelf environments. Comparison with coeval acritarch microflora from the Yangtze Platform, South China, shows an overall similarity between Baltoscandian and South Chinese phytoplankton. The widespread uniformity in the fossil microphytoplankton may be related to the extensive global 'evae' sea-level transgression, which characterized the Billingen time. This suggests that during the Tremadoc through early Arenig times, acritarch assemblages displayed essentially an undifferentiated cold-water and oceanic character along the whole margin of Perigondwana in the South, as well as on the South Chinese and Baltic platforms, at middle latitudes (Mediterranean oceanic Realm). Despite this overall similarity, however, some typical taxa of the high-latitude Mediterranean Province (Arbusculidium, Coryphidium and Striatotheca) occur in South China, but are absent in Baltica. This discrepancy is explained as caused by differences in climatic and physiographic conditions that prevailed at the two palaeocontinents at this time. The inferred pattern of oceanic circulation during the Lower Ordovician is consistent with the palynological evidence of a prevailing warmer climate in Baltica than in South China, although the two palaeocontinents occupied the same palaeolatitudinal position.     

Essentialism, history, and biological taxa

de Queiroz (1995), Griffiths (1999) and LaPorte (2004) offer a new version of essentialism called "historical essentialism". According to this version of essentialism, relations of common ancestry are essential features of biological taxa. The main type of argument for this essentialism proposed by Griffiths (1999) and LaPorte (2004) is that the dominant school of classification, cladism, defines biological taxa in terms of common ancestry. The goal of this paper is to show that this argument for historical essentialism is unsatisfactory: cladism does not assume that relations of common ancestry are essential attributes of biological taxa. Therefore, historical essentialism is not justified by cladism.     

Isolation-by-time population structure in potamodromous Dourado <Emphasis Type="Italic">Salminus brasiliensis</Emphasis> in southern Brazil

Isolation-by-distance is recognized as a useful model for describing the spatial distribution of gene frequencies depending on dispersal characteristics of the species under study. However, some species may have populations that occupy the same geographic distribution during the breeding season yet reproduce at different time periods resulting in isolation-by-time (IBT). IBT may complicate investigations of spatial population structure if samples are obtained from multiple discrete time periods or may remain undiscovered if surveys are conducted with limited temporal scope. IBT has been observed in several studies of anadromous fishes (primarily salmon) as well as a few examples in taxa such as frogs, plants, birds and insects, but has not been rigorously tested in freshwater fishes. In this study, we assessed spatial and temporal genetic variation and tested for IBT in Dourado (Salminus brasiliensis), a large and commercially-important potamodromous fish species found in multiple river basins of South America. Using 11 polymorphic microsatellite loci, we estimated genetic differentiation of 317 adult Dourado collected monthly during the breeding season at three locations along the Uruguay River in southern Brazil. Analyses identified three populations that were clustered in time (i.e. early, middle and late), suggesting an IBT pattern of population structure with no significant spatial structure. Our results contribute to the mounting evidence across a wide range of taxa that suggests IBT may be more common that currently considered, even for species with very high dispersal capabilities such as potamodromous fishes.