Biomechanics of the release of sex pheromone in moths: effects of body posture on local airflow

ABSTRACT. The calling posture of Spilosoma congrua Walker (Lepidoptera: Arctiidae) affects local airflow in ways that may impact on the release of chemical signals. Dried specimens of S. congrua imitating resting moths, calling moths, and moths with intermediate postures were placed in a wind tunnel. The wind speed was measured near the abdomenal tip where sex pheromone emission occurs. The calling posture, wings-up, gave significantly greater mean wind speeds near the surface of the sex pheromone gland, effectively eliminating the dead air space that surrounds a non-calling moth. The calling posture also decreased the relative intensity of turbulence near the pheromone gland surface.     

Feeding Behavior, Aggression, and the Conservation Biology of Flamingos: Integrating Studies of Captive and Free-ranging Birds

SYNOPSIS. Flamingos (Aves, Phoenicopteridae) represent an ancientlineage of long-legged, microphagous, colonial wading birds.Although often perceived as tropical, flamingo distributionis more closely tied to the great deserts of the world, andto hypersaline sites, than it is to equatorial regions. Manyaspects of flamingo behavior and ecology can be studied in captivity.Experimental studies involving captive birds, when combinedwith observational studies of free-ranging birds, offer researchersopportunities to address questions that are unanswerable withfield work alone. Zoo populations of flamingos are prime candidatesfor such studies. Here, we use samples of our own work to illustrate the synergisticeffects of combining zoo and field research. Our first exampledescribes how studies of salt tolerance in captive birds areplaying a key role in assessing the impact of salt as an ecologicaldeterminant of flamingo distribution. Our second example describeshow aggression and dominance interactions affect the feedingbehavior of flamingos. We assess the implications of this researchin terms of both avicultural practices and the fundamental ecologyof the birds. We believe that similar collaborations involvingother zoo animals would yield comparatively productive results.     

Detection Dogs: An Effective Technique for Bush Dog Surveys

ABSTRACT Detailed ecological data on the bush dog (Speothos venaticus) have been lacking, since standard field techniques, such as camera traps, have had little success recording their presence. This study eliminates dependence on visitation rate and switches the focus to locating evidence (e.g., olfactory) associated with the species’ natural behavior and movement patterns. Over a 3-month period, a detection dog located multiple (n = 11, 4 confirmed and 7 potential) bush dog areas in Upper Paraná Atlantic Forest of Misiones Argentina. These positive results demonstrate that detection dogs can provide species-specific data on the bush dog despite the rugged terrain and dense forest vegetation they may occupy. The ecological data collected using this technique allow effective conservation strategies to be developed, wildlife corridors and biological crossings to be designed, and species distributions to be examined.     

Gray whale Eschrichtius robustus population and stock identity

• 1 In response to conservation and management concerns about gray whale Eschrichtius robustus population and stock structure, we provide an overview of the life history and ecology of gray whales as a context for discussion of population and stock structure within the species. Historically eastern and western North Pacific gray whales were managed separately because: (i) their ranges do not overlap; (ii) genetic analyses indicate that the two populations are significantly different; and (iii) eastern gray whales have increased in abundance over the past century while western gray whales have not.
• 2 Here, we review gray whale migration timing and segregation, feeding and prey species, and reproduction and reproductive behaviour. For the eastern and western gray whale, we review their distribution, history of exploitation, abundance and current status, although most of what is known is founded on the better studied eastern gray whale and only implied for the lesser known western gray whale. Methods to investigate population and stock identity are reviewed including genetics, morphology, chemical signatures, carbon isotopes, parasites, photographic identification and trends in abundance.
• 3 While the evidence indicates that there is at least some degree of mixing within each of the gray whale populations, no stocks or sub‐stocks can be defined. Population structure is not evident in nuclear data, and because selection occurs primarily on the nuclear genome, it is unlikely that there is structuring within each population that could result in evolutionary differences. For western gray whales, there are insufficient data to assess the plausibility of stock structure within the population, owing to its extremely depleted state. Research on eastern gray whales has focused mostly on documenting changes in abundance, feeding biology and behaviour, and suggests separate breeding groups to be unlikely. Both males and females are promiscuous breeders lending little opportunity for the nuclear genome to be anything other than well mixed as is suggested by the high haplotypic diversity of the eastern population.
• 4 The available data strongly indicate that western gray whales represent a population geographically isolated from eastern gray whales and therefore that the western and eastern populations should be treated as separate management units.

     

The regional variation of aboveground live biomass in old-growth Amazonian forests

The biomass of tropical forests plays an important role in the global carbon cycle, both as a dynamic reservoir of carbon, and as a source of carbon dioxide to the atmosphere in areas undergoing deforestation. However, the absolute magnitude and environmental determinants of tropical forest biomass are still poorly understood. Here, we present a new synthesis and interpolation of the basal area and aboveground live biomass of old‐growth lowland tropical forests across South America, based on data from 227 forest plots, many previously unpublished. Forest biomass was analyzed in terms of two uncorrelated factors: basal area and mean wood density. Basal area is strongly affected by local landscape factors, but is relatively invariant at regional scale in moist tropical forests, and declines significantly at the dry periphery of the forest zone. Mean wood density is inversely correlated with forest dynamics, being lower in the dynamic forests of western Amazonia and high in the slow‐growing forests of eastern Amazonia. The combination of these two factors results in biomass being highest in the moderately seasonal, slow growing forests of central Amazonia and the Guyanas (up to 350 Mg dry weight ha^?1) and declining to 200–250 Mg dry weight ha^?1 at the western, southern and eastern margins. Overall, we estimate the total aboveground live biomass of intact Amazonian rainforests (area 5.76 × 10⁶ km² in 2000) to be 93±23 Pg C, taking into account lianas and small trees. Including dead biomass and belowground biomass would increase this value by approximately 10% and 21%, respectively, but the spatial variation of these additional terms still needs to be quantified.     

Comparative vegetative anatomy and systematics of the angraecoids (Vandeae, Orchidaceae) with an emphasis on the leafless habit

The vegetative anatomy and morphology of 142 species of the angraecoid orchids (Angraecinae + Aerangidinae) and 18 species of Aeridinae were examined using light and scanning electron microscopy. Leafless members of Vandeae were of particular interest because of their unique growth habit. Leafy and leafless members of Angraecinae and Aerangidinae were examined and compared with specimens of Aeridinae. Vandeae were homogeneous in both leaf and root anatomy. A foliar hypodermis and fibre bundles were generally absent. Stegmata with spherical silica bodies were found associated with sclerenchyma and restricted to leaves in almost all specimens examined. Distinct inner tangential wall thickenings of the endovelamen occurred in several vandaceous genera. Exodermal proliferations and aeration units commonly occurred in both leafy and leafless Vandeae. Cladistic analyses of Angraecinae and Aerangidinae with members of Aeridinae and Polystachyinae as outgroups using 26 structural characters resulted in 20 000+ equally parsimonious trees. Vandeae formed the only well-supported clade in bootstrap analyses and were characterized by having a monopodial growth habit, spherical stegmata, loss of mucilage, and loss of tilosomes.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 165–218.     

Connectivity counts: disentangling effects of vegetation structure elements on the searching movement of a parasitoid

1. A heterogeneous habitat structure can have a profound impact on foraging carnivorous arthropods. In the present study, we examined which elements of complex vegetation structure influence the searching movement of a parasitoid model organism. 2. Previous field work showed that tall and dense vegetation reduces the parasitism success of the eulophid egg parasitoid Oomyzus galerucivorus while the probability of host egg deposition increased close to plant tips. 3. In laboratory bioassays, dried grass stems were arranged according to the natural situation in different setups. The wasps' walking time on stems increased with increasing stem height and density. High stem density decreased the walking time of the parasitoids on the ground and an increased stem height reduced the propensity to fly to the ground. Connectivity had a minor positive effect on the number of stem contacts, but considerably reduced the number of wasps reaching the upper part of grass stems by two‐thirds. 4. Thus, although enhanced vegetation complexity enhances walking activity of the parasitoids in the vegetation, laying eggs at the tip of long grass stems in dense vegetation can be an adaptive strategy for the host, as it maximises the number of connections between plant parts to cross by parasitoids before reaching the host. The connection points disorient the wasps, which lose time, reverse their direction or fly away.     

Soil heterogeneity buffers community response to climate change in species‐rich grassland

Climate change impacts on vegetation are mediated by soil processes that regulate rhizosphere water balance, nutrient dynamics, and ground‐level temperatures. For ecosystems characterized by high fine‐scale substrate heterogeneity such as grasslands on poorly developed soils, effects of climate change on plant communities may depend on substrate properties that vary at the scale of individuals (<m²), leading to fine‐scale shifts in community structure that may go undetected at larger scales. Here, we show in a long‐running climate experiment in species‐rich limestone grassland in Buxton, England (UK), that the resistance of the community to 15‐year manipulations of temperature and rainfall at the plot scale (9 m²) belies considerable community reorganization at the microsite (100 cm²) scale. In individual models of the abundance of the 25 most common species with respect to climate treatment and microsite soil depth, 13 species exhibited significant soil depth affinities, and nine of these have shifted their position along the depth gradient in response to one or more climate treatments. Estimates of species turnover across the depth gradient reviewed in relation to measurements of water potential, nitrogen supply, pH, and community biomass suggest that communities of shallow microsites are responding directly to microenvironmental changes induced by climate manipulation, while those of the deepest microsites are shifting in response to changes in competitive interference from more nutrient‐demanding species. Moreover, for several species in summer drought and winter heated treatments, climate response in deep microsites was opposite that of shallow microsites, suggesting microsite variation is contributing to community stability at the whole‐plot level. Our study thus demonstrates a strong link between community dynamics and substrate properties, and suggests ecosystems typified by fine‐scale substrate heterogeneity may possess a natural buffering capacity in the face of climate change.