Habitat choice of some field-inhabiting carabid beetles (Coleoptera: Carabidae) studied by recapture of marked individuals

ABSTRACT.

• 1 Habitat choice of some field-inhabiting carabid beetles was studied in the field, and included the adult-overwintering Bembidion lampros Herbst, Pterostichus cupreus L. and Agonum dorsale Pontoppidan, and the larval-overwintering Trechus secalis Paykull, Pterostichus melanarius Illiger, P.niger Schaller and Harpalus rufipes De Geer. These were compared to the forest-inhabiting and adult-overwintering species, Carabus nemoralis Müller.
• 2 Marked beetles were released in the centre of a circular enclosure which was placed on the edge between a cereal field and a wood. The direction of movement in this circle was compared with that in a control circle placed entirely in the cereal field.
• 3 In the field/wood circle, adult-overwinterers and the larval-overwin-terer H.rufipes choose to move into the cereal field. The majority of T.secalis. P.melanarius and C.nemoralis, however, moved into the wood, while P.niger exhibited no preference.
• 4 In the field circle, adult-overwinterers moved towards the more sun-exposed parts of the circle, whereas the movements of larval-overwin-terers were random.
• 5 Some species-specific characteristics considered important for habitat choice by these carabid beetles, and the relevance of these characteristics for their dispersal behaviour are discussed.

     

Cladistic analysis of the Cirripedia Thoracica

We present a cladistic analysis of the Cirripedia Thoracica using morphological characters and the Acrothoracica and Ascothoracida as outgroups. The list of characters comprised 32 shell and soft body features. The operational taxonomic units (OTUs) comprised 26 well-studied fossil and extant taxa, principally genera, since uncertainty about monophyly exists for most higher ranking taxonomic units. Parsimony analyses using PAUP 3.1.1 and Hennig86 produced 189 trees of assured minimal length. We also examined character evolution in the consensus trees using MacClade and Clados. The monophyly of the Balanomorpha and the Verrucomorpha sensu stricto is confirmed, and all trees featured a sister group relationship between the ‘living fossil Neoverruca and me Brachylepadomorpha. In the consensus trees the sequential progression of ‘pedunculate‘sister groups up to a node containing Neolepas also conforms to current views, but certain well-established taxa based solely on plesiomorphies stand out as paraphyletic, such as Pedunculata (= Lepadomorpha); Eolepadinae, Scalpellomorpha and Chthamaloidea. The 189 trees differed principally in the position of shell-less pedunculates, Neoverruca, the scalpelloid Capitulum, and the interrelationships within the Balanomorpha, although the 50% majority rule consensus tree almost fully resolved the latter. A monophyletic Sessilia comprising both Verrucomorpha and Balanomorpha appeared among the shortest trees, but not in the consensus. A tree with a monophyletic Verrucomorpha including Neoverruca had a tree length two steps longer than the consensus trees. Deletion of all extinct OTUs produced a radically different tree, which highlights the importance of fossils in estimating cirripede phylogeny. Mapping of our character set onto a manually constructed cladogram reflecting die most recent scenario of cirripede evolution resulted in a tree length five steps longer than any of our shortest trees. Our analysis reveals that several key questions in cirripede phylogeny remain unsolved, notably the position of shell-less forms and the transition from ‘pedunculate‘to ‘sessile‘barnacles. The inclusion of more fossil species at this point in our understanding of cirripede phylogeny will only result in even greater levels of uncertainty. When constructing the character list we also identified numerous uncertainties in the homology of traits commonly used in discussing cirripede evolution. Our study highlights larval ultrastructure, detailed studies of early ontogeny, and molecular data as the most promising areas for future research.     

A PORTABLE DIGITAL SOUND EMITTER FOR INTERACTIVE PLAYBACK OF ANIMAL VOCALISATIONS

ABSTRACT

A new portable digital sound emitter (DSE) for normal and interactive playback of sound signals in the field and in the laboratory is described together with two examples of applications of the DSE in interactive field experiments. The DSE may be loaded with a broad spectrum of digitised sounds, e.g. artificial signals or natural animal vocalisations, and it is controlled via the keyboard of a portable PC running a dedicated program. This program, which can be tailored to support a vast number of different demands, enables the experimenter to start and stop the analog output from the DSE at any time and to choose freely between the available sounds and playback modes. The use of the DSE for interactive playback experiments therefore is only limited by the ability of the operator to perceive the vocalisations of the participating animal and to operate the keyboard of the PC.     

Modeling Harvest Intensity of Sooty Shearwater Chicks by Rakiura Māori in New Zealand

Abstract: Cultural evidence suggests that sooty shearwater (Puffinus griseus) chicks have been harvested by Rakiura Māori on islands in southern New Zealand since prehistoric times. Concerns exist that modern harvests may be impacting sooty shearwater abundance. We modeled human-related and ecological determinants of harvest (total no. of individuals harvested) of sooty shearwater chicks on 11 islands and examined the relationship between shearwater abundance and harvesting rates (chicks/hr) and harvester behavior throughout the harvesting season. Models best explaining variation in harvest between harvesting areas (manu), for both the early and late parts of the harvesting season, included harvester-days (included in all models with change in deviance information criteria [ΔDIC], ΔDIC < 8.36 and ΔDIC < 11.5, for the early and late periods, respectively). Other harvest determinants included shearwater density, size of the manu, and number of people helping harvesters (all included in the top 5 models within ΔDIC = 2.25 for the late period). Areas harvested by several families under a common-property harvesting system had higher harvest intensity for their size (24% points higher, 95% credible interval 11–36%) than those managed as an exclusive resource for one family. The slowest harvesters spent more time harvesting but on average only harvested 36% (95% credible interval 15–65%) and 34% (95% credible interval 12–63%) of the harvest taken by the fastest harvesters during the early and late periods, respectively. Our results highlight the possibility of elevated harvest intensity as the population of harvesters increases. However, our models suggested that a corresponding reduction in harvesting rate at low prey densities during the most productive period could potentially regulate harvest intensity. Future research will integrate these results into prospective shearwater demographic models to assess the utility of a range of harvesting strategies in ensuring harvest sustainability.     

Wolf Movement Patterns: a Key to Estimation of Kill Rate?

Abstract: To estimate wolf (Canis lupus) kill rates from fine-scale movement patterns, we followed adult wolves in 3 territories of the Scandinavian wolf population using Global Positioning Systems (GPS) during the winters of 2001–2003. The resulting 6 datasets of 62–84 study days gave a total of 8,747 hourly GPS positions. We visited clusters of positions in the field on average 8.8 days after positioning and found moose (Alces alces) killed by wolves during the study period on 74 (8%) of the 953 clusters. The number of positions and visits to a cluster, their interaction, and the proportion of afternoon positions were significant fixed effects in mixed logistic-regression models predicting the probability of a cluster containing a wolf-killed moose. The models, however, displayed a poor goodness-of-fit and were not a suitable tool for estimating kill rates from positioning data alone. They might be used to reduce fieldwork by excluding unlikely clusters, although the reduction was not substantial. We discuss proximate factors (i.e., human disturbance and access to prey) as well as ultimate factors (i.e., social organization, intra-guild dominance, and litter size) as potential causes of the observed high temporal and spatial variation in prey-handling. For similar future kill-rate studies, we recommend increasing field efforts and shortening positioning intervals.     

Multistage,Long-Range Natal Dispersal by a Global Positioning System-Collared Scandinavian Wolf

Abstract: We document a new record dispersal for wolves worldwide. The natal straight-line dispersal distance of a Global Positioning System-collared female wolf from the Scandinavian population was 1,092 km from southeast Norway to northeast Finland, with a multistage actual travel distance of >10,000 km. Natural gene flow to the isolated, inbred Scandinavian wolf population may occur if survival of dispersers is improved.     

Will a 385 million year‐struggle for light become a struggle for water and for carbon? – How trees may cope with more frequent climate change‐type drought events

Trees are exceptional organisms that have evolved over some 385 million years and have overtaken other plants in order to harvest light first. However, this advantage comes with a cost: trees must transport water all the way up to their crowns and inherent physical limitations make them vulnerable to water deficits. Because climate change scenarios predict more frequent extreme drought events, trees will increasingly need to cope with water stress. Recent occurrences of climate change‐type droughts have had severe impacts on several forest ecosystems. Initial experimental studies have been undertaken and show that stomatal control of water loss hinders carbon assimilation and could lead to starvation during droughts. Other mechanisms of drought‐induced mortality are catastrophic xylem dysfunction, impeded long‐distance transport of carbohydrates (translocation) and also symplastic failure (cellular breakdown). However, direct empirical support is absent for either hypothesis. More experimental studies are necessary to increase our understanding of these processes and to resolve the mystery of drought‐related tree mortality. Instead of testing the validity of particular hypothesis as mechanisms of drought‐induced tree mortality, future research should aim at revealing the temporal dynamics of these mechanisms in different species and over a gradient of environmental conditions. Only such studies will reveal whether the struggle for light will become a struggle for water and/or for carbon in drought‐affected areas.     

Streamlining of plant patches in streams

1. Plants in shallow streams often grow in well‐defined monospecific patches experiencing a predictable unidirectional flow, though of temporally variable velocity. During maximum patch development in summer we studied: (i) the shape and streamlining of 59 patches of Callitriche cophocarpa, (ii) allometric relationships between canopy size and sediment area colonized by roots (root area) and (iii) fine‐scale flow gradients for a representative patch exposed to a range of velocities to evaluate relationships between patch shape and physical impact. 2. Canopy and root area viewed from above were elongated and streamlined in the flow direction, while uniform vegetative growth in all directions from a single colonizing shoot would have generated a circular form. Canopies were slightly wider in the upstream part than in the gradually tapering part downstream and the maximum height to length ratio averaged 0.25. The canopy and root area of the patches were more elongate and slender in sites with shallow water, where currents accelerate alongside patches and restrict lateral expansion, compared to deeper sites where currents can pass above the canopy. Similarly, the frontal area relative to planform area or root area was significantly lower in shallow water . Canopy shape and indices of streamlining did not change significantly with approach velocity (0.02–0.40 m s^?1), either because canopy shape is not sensitive to approach velocity or summer velocities were too low to induce such changes. 3. Sediment elevation within patches (avg. 4.1 cm) increased significantly with patch length, but did not differ between unstable sand or more stable coarse sediment for the same patch length. Shape of canopy and root area did not change significantly with sediment type. 4. Pressure drag on the canopy as a whole is probably reduced by its rounded front, restricted height and overall slender form with a low frontal area, while the downstream overhanging canopy increases drag compared to an ideal streamlined object. Across a 100‐fold range of root areas from 0.01 to 1 m², the frontal area of the canopy increased 29 times, planform area increased 38 times and volume increased 76 times, suggesting a trade‐off between physical impact of flow, light interception and anchoring strength. 5. The canopy was compressed at high approach velocities, with low current velocity within the canopy while steep velocity gradients developed across the exposed outer surfaces as the diverted flow accelerated. Because drag processes are additive, and exist at different spatial scales and Reynolds numbers on the surface and inside of plant canopies, direct measurements on entire canopies under controlled conditions are needed to test the functional importance of their shape, size and porosity to flow.     

matesoft: a program for deducing parental genotypes and estimating mating system statistics in haplodiploid species

With the advent of sophisticated genetic markers, studies on mating systems and reproductive apportionment have become increasingly feasible. In particular, paternity analyses in haplodiploid species have gained in power as hemizygous paternal genotypes allow maternal and paternal genotypes to be directly inferred from offspring genotypes. The computer program matesoft offers both newly developed algorithms for inferring maternal and paternal genotypes, and integrated estimation and correction procedures for calculating mating frequency statistics. Standard data are offspring genotypes of male‐haplodiploid organisms, including social Hymenoptera.