Temperature and water potential relations of tropical Trametes and other wood-decay fungi from the indigenous forests of Zimbabwe

Three isolates each, of nine different Trametes and five other wood inhabiting basidiomycetes, were collected from the indigenous forests of Zimbabwe, and the impact of temperature (20-60 degrees C), osmotic and matric potential (-0.5 to - 8.0 MPa), and their interactions on in vitro growth compared. Generally, there was no significant difference between growth of isolates of the same species in relation to temperature. Temperature relationships of the species studied correlated well with their geographic distributions. Species occurring in hot, dry regions tolerated a wide temperature range, with some showing unusually high thermotolerance (55 degrees, T. socotrana, T. cingulata and T. cervina). There were significant intra-strain differences for individual species in relation to solute potential on glycerol-modified media. Generally, growth of ail species was better on glycerol- and KCl-modified osmotic media than on a metrically-modified medium (PEG 8000) at 25, 30 and 37 degrees. The limits for growth on the osmotic media were significantly wider than matric medium, being - 4.5 to - 5.0 and - 2.5 to - 4.5 MPa, respectively. An Irpex sp. grew at lower water potentials than all other species, with good growth at - 7.0 MPa. This study suggests that the capacity of these fungi for effective growth over a range of temperatures, osmotic and matric potentials contributes to their rapid wood decay capacities in tropical climates.

Ornithokinin (avian bradykinin) from the skin of the Chinese bamboo odorous frog, Odorrana versabilis

One of the most widespread and abundant families of pharmacologically active peptides in amphibian defensive skin secretions is the bradykinins and related peptides. Despite retaining certain primary structural attributes that assign them to this peptide family, bradykinins and related peptides are unique among amphibian skin peptides in that they exhibit a wide range of primary structural variations, post-translational modifications and/or N-terminal or C-terminal extensions. Initially it was believed that their high degree of primary structural heterogeneity was reflective of random gene mutations within species, but latterly, there is an increasing body of evidence that the spectrum of structural modifications found within this peptide family is reflective of the vertebrate predator spectrum of individual species. Here we report the discovery of ornithokinin (avian bradykinin – Thr6, Leu8-bradykinin) in the skin secretion of the Chinese bamboo odorous frog, Odorrana versabilis. Molecular cloning of its biosynthetic precursor-encoding cDNA from a skin secretion-derived cDNA library revealed a deduced open-reading frame of 86 amino acid residues, encoding a single copy of ornithokinin towards its C-terminus. The domain architecture of this ornithokinin precursor protein was consistent with that of a typical amphibian skin peptide and quite different to that of the ornithokininogen from chicken plasma. Ornithokinin was reported to induce hypotension in the chicken and to contract the chicken oviduct but to have no obvious effect on the rat uterus. However, in this study, synthetic ornithokinin was found to contract the rat ileum (EC50 = 539 nM) and to increase contraction frequency in the rat uterus (EC50 = 1.87 μM).

Effects of environment and an introduced invertebrate species on the structure of benthic macroinvertebrate species at the catchment level

Biotic interactions such as predation and competition can influence aquatic communities at small spatial scales, but they are expected to be overridden by environmental factors at large scales. The continuing threat to freshwater biodiversity of biological invasions indicates that biotic factors do, however, have important structuring roles. In Irish rivers, the native amphipod Gammarus duebeni celticus has become locally extinct, ostensibly through differential predation by the more aggressive and introduced G. pulex. This mechanism explains impacts of G. pulex at within-river spatial scales on native macroinvertebrate community diversity, including declines in ephemeropterans, plecopterans, dipterans and oligochaetes. To determine if these patterns are predictable at larger spatial scales, we assessed patterns in native macroinvertebrate communities across river sites of the Erne catchment in 1998 and 1999, in conjunction with the distribution of G. pulex and G. d. celticus. In both years, G. pulex dominated invaded sites, whereas G. d. celticus occurred at low abundance in uninvaded sites. In both years, invaded sites had lower diversity and fewer pollution sensitive invertebrate species than un-invaded sites. Community ordination in 1998 showed that invaded sites had higher conductivity, smaller substrate particle size and comprised a lower proportion of pollution sensitive taxa including Ephemeroptera and Plecoptera. In contrast, in 1999, conductivity was the only variable explaining site ordination along axis 1, but was unable to separate sites with respect to invasion status. A second explanatory axis separated sites with respect to invasion status, with invaded sites having fewer taxa, including lower abundance of ephemeropterans, dipterans and plecopterans. Laboratory experiments examined the potential role of differential predation between the two Gammarus species in explaining these taxon specific patterns in the field. Survival of the ephemeropterans, Ephemerella ignita and Ecdyonurus venosus and the isopod, Asellus aquaticus, was lower when interacting with G. pulex than with G. d. celticus. This study indicates that G. putex may alter invertebrate community structure at scales beyond those detected within individual rivers. However, effects may be influenced by gradients in physico-chemistry, which may be temporal or depend on catchment characteristics. Invasions by amphipods have increased globally, thus comprehensive assessments of their impacts and of other aquatic invaders, may only be apparent when studies are conducted at a range of spatio-temporal scales.

Building on IUCN regional red lists to produce lists of species of conservation priority: a model with Irish bees

A World Conservation Union (IUCN) regional red list is an objective assessment of regional extinction risk and is not the same as a list of conservation priority species. Recent research reveals the widespread, but incorrect, assumption that IUCN Red List categories represent a hierarchical list of priorities for conservation action. We developed a simple eight-step priority-setting process and applied it to the conservation of bees in Ireland. Our model is based on the national red list but also considers the global significance of the national population; the conservation status at global, continental, and regional levels; key biological, economic, and societal factors; and is compatible with existing conservation agreements and legislation. Throughout Ireland, almost one-third of the bee fauna is threatened (30 of 100 species), but our methodology resulted in a reduced list of only 17 priority species. We did not use the priority species list to broadly categorize species to the conservation action required; instead, we indicated the individual action required for all threatened, near-threatened, and data-deficient species on the national red list based on the IUCN's conservation-actions template file. Priority species lists will strongly influence prioritization of conservation actions at national levels, but action should not be exclusive to listed species. In addition, all species on this list will not necessarily require immediate action. Our method is transparent, reproducible, and readily applicable to other taxa and regions.

High levels of genetic structuring as a result of population fragmentation in the tropical tree species Caesalpinia echinata Lam.

We have investigated levels of genetic diversity within and among seven remnant populations of Caesalpinia echinata Lam., an endangered species found as fragmented populations in three major areas around the coastal regions of Brazil. Using amplified fragment length polymorphism (AFLP) genetic markers, we detected levels of within-population genetic diversity ranging from 0.092 to 0.163, with the lowest values generally being found in the smallest populations. Estimates of between-population genetic differentiation were strongly correlated with geographical distance ( r = 0.884, p <0.001), which, along with a neighbour-joining phylogenetic analysis, strongly suggested high levels of genetic isolation by distance. Over half (62%) of the total genetic diversity was partitioned between populations, further highlighting the genetic distinctness of individual populations. Taken together, these results suggest that fragmentation has led to an increase in population differentiation between fragments of C. echinata. These formations will be of great value in the development of conservation plans for species exhibiting high levels of genetic differentiation due to fragmentation, such as indication of conservation unit size, which populations should be chosen as priority in conservation plans and which samples should be introduced in areas with a low number of individuals of brazilwood.

The energetics of huddling in two species of mole-rat (Rodentia: Bathyergidae)

Small rodents with a large surf ace-area-to-volume ratio and a high thermal conductance are likely to experience conditions where they have to expend large: amounts of energy in order to maintain a constant body temperature at low ambient temperatures. The survival of small rodents is thus dependent on their ability to reduce heat loss and increase heat production at low ambient temperatures. Two such animals are the social subterranean rodents Cryptomys damarensis (the Damaraland mole-rat) and Cryptomys hottentotus natalensis (the Natal mole-rat). This study examined the energy savings associated with huddling as a behavioural thermoregulatory mechanism to conserve energy in both these species. Individual oxygen consumption (VO2) was measured in groups ranging in size from one to 15 huddling animals for both species at ambient temperatures of 14, 18, 22, 26 and 30 degrees C. Savings in energy (VO2) were then compared between the two species. Significant differences in VO2 (p

Algal epiphytes of Zostera marina: Variation in assemblage structure from individual leaves to regional scale

Data from a hierarchical study of four Zostera marina beds in Wales were used to identify the spatial scales of variation in epiphyte assemblages. There were significant within and among bed differences in assemblage structure. The differences in assemblage structure with spatial scale generally persisted when species identifications were aggregated into functional groups. There was also significant within and among bed variability in Zostera density and average length. Local variations in Zostera canopy variables at the quadrat scale (total leaf length, average leaf length and leaf density per quadrat) were not related to epiphyte species richness nor to the structure of the assemblage. In contrast, individual leaf length was significantly related to species richness in two of the beds and the structure of epiphyte assemblages was always related to individual leaf lengths. The absence of links between quadrat scale measurements of canopy variables and assemblage structure may reflect the high turnover of individual Zostera leaves. Experimental work is required to discriminate further between the potential causes of epiphyte assemblage variation within and between beds. No bed represented a refuge where a rare species was abundant. If a species was uncommon at the bed scale, it was also uncommon in beds where it occurred. The heterogeneous assemblages found in this study suggest that a precautionary approach to conservation is advisable.

cpDNA-RFLP in Ceramium (Rhodophyta): Intraspecific polymorphism and species-level phylogeny

Restriction fragment length polymorphism (RFLP) analysis of chloroplast (cp) DNA is a powerful tool for the study of microevolutionary processes in land plants, yet has not previously been applied to seaweed populations. We used cpDNA-RFLP, detected on Southern blots using labeled total plastid DNA, to search for intraspecific and intrapopulational cpDNA RFLP polymorphism in two species of the common red algal genus Ceramium in Ireland and Britain. In C. botryocarpum one polymorphism was detected in one individual among 18 from two populations. Twenty-six individuals of C. virgatum from five populations at three locations exhibited a total of four haplotypes. One was frequent (80.8% of individuals); the others were rare (7.7, 7.7 and 4.2%) and were private to particular populations. Polymorphism was observed in two populations. The corrected mean was 2.26 +/- 0.36 haplotypes per population, which was within the typical range determined for higher plants using similar techniques. The spatial distribution of haplotypes was heterogeneous, with highly significant population differentiation (P = 0.00018; Fisher's exact test). Intraspecific polymorphism in C. virgatum had no impact on species-level phylogenetic reconstruction. This is the first unequivocal report of both intraspecific and intrapopulational cpDNA-RFLP polymorphism in algae.

Size-selective fishing drives species composition in the Celtic Sea

Fishing alters community size structure by selectively removing larger individual fish and by changing the relative abundance of different-sized species. To assess the relative importance of individual-and species-level effects, two indices of fish community structure were compared, the relative abundance of large fish individuals (large fish indicator, LFI) and the relative abundance of large fish species (large species indicator, LSI). The two indices were strongly correlated for empirical data from the Celtic Sea and for data from simulated model communities, suggesting that much of the variability in the LFI is caused by shifts in the relative abundance of species (LSI). This correlation is explained by the observation that most of the biomass of a given species is spread over few length classes, a range spanning the factor 2 of individual length, such that most species contributed predominantly to either the small or the large component of the LFI. The results suggest that the effects of size-selective fishing in the Celtic Sea are mediated mainly through changes in community composition.

Animal foraging from an individual perspective: an object orientated model

A model system, HOOFS (Hierarchical Object Orientated Foraging Simulator), has been developed to study foraging by animals in a complex environment. The model is implemented using an individual-based object-orientated structure. Different species of animals inherit their general properties from a generic animal object which inherits from the basic dynamic object class. Each dynamic object is a separate program thread under the control of a central scheduler. The environment is described as a map of small hexagonal patches, each with their own level of resources and a patch-specific rate of resource replenishment. Each group of seven patches (0th order) is grouped into a Ist order super-patch with seven nth order super-patches making up a n + 1th order super-patch for n up to a specified value. At any time each animal is associated with a single patch. Patch choice is made by combining the information on the resources available within different order patches and super-patches along with information on the spatial location of other animals. The degree of sociality of an animal is defined in terms of optimal spacing from other animals and by the weighting of patch choice based on social factors relative to that based on food availability. Information, available to each animal, about patch resources diminishes with distance from that patch. The model has been used to demonstrate that social interactions can constrain patch choice and result in a short-term reduction of intake and a greater degree of variability in the level of resources in patches. We used the model to show that the effect of this variability on the animal's intake depends on the pattern of patch replenishment. (C) 1998 Elsevier Science B.V. All rights reserved.</p>

Freshwater pearl mussels show plasticity of responses to different predation risks but also show consistent individual differences in responsiveness

Animals often show behavioural plasticity with respect to predation risk but also show behavioural syndromes in terms of consistency of responses to different stimuli. We examine these features in the freshwater pearl mussel. These bivalves often aggregate presumably to reduce predation risk to each individual. Predation risk, however, will be higher in the presence of predator cues. Here we use dimming light, vibration and touch as novel stimuli to examine the trade-off between motivation to feed and motivation to avoid predation. We present two experiments that each use three sequential novel stimuli to cause the mussels to close their valves and hence cease feeding. We find that mussels within a group showed shorter closure times than solitary mussels, consistent with decreased vulnerability to predation in group-living individuals. Mussels exposed to the odour of a predatory crayfish showed longer closures than control mussels, highlighting the predator assessment abilities of this species. However, individuals showed significant consistency in their closure responses across the trial series, in line with behavioural syndrome theory. Our results show that bivalves trade-off feeding and predator avoidance according to predation risk but the degree to which this is achieved is constrained by behavioural consistency. © 2011 Elsevier B.V.

Resonant Rayleigh light scattering response of individual Au nanoparticles to antigen--antibody interaction

A proof-of-concept study was reported on analysis of antigen–antibody recognition based on resonant Rayleigh scattering response of single Au nanoparticles in an imaging chamber. As benefited by a traditional dark-field microscope and a spectrograph, individual Au nanoparticles (30 nm) were observed with high signal-to-noise ratio and they were effectively utilized to monitor changes in refractive index induced by specific binding of the adsorbates. Using PSA antigen as a model, a LSPR ?max shift of about 2.85 nm was recorded for a molecular binding corresponding to 0.1 pg ml-1 of the protein biomarker. This result successfully demonstrates a non-labeling detection system for proteins as well as thousands of different chemical or biological species, and it possesses a great potential as a sensitive, on-chip and multiplexing detection.

Emerging asymmetric interactions between forage and predator fisheries impose management trade-offs

A size and trait-based marine community model was used to investigate interactions, with potential implications for yields, when a fishery targeting forage fish species (whose main adult diet is zooplankton) co-occurs with a fishery targeting larger-sized predator species. Predicted effects on the size structure of the fish community, growth and recruitment of fishes, and yield from the fisheries were used to identify management trade-offs among the different fisheries. Results showed that moderate fishing on forage fishes imposed only small effects on predator fisheries, whereas predator fisheries could enhance yield from forage fisheries under some circumstances.

Are there species smaller than 1 mm?

The rapid advance in genetic sequencing technologies has provided an unprecedented amount of data on the biodiversity of meiofauna. It was hoped that these data would allow the identification and counting of species, distinguished as tight clusters of similar genomes. Surprisingly, this appears not to be the case. Here, we begin a theoretical discussion of this phenomenon, drawing on an individual-based ecological model to inform our arguments. The determining factor in the emergence (or not) of distinguishable genetic clusters in the model is the product of population size with mutation rate—a measure of the adaptability of the population as a whole. This result suggests that indeed one should not expect to observe clearly distinguishable species groupings in data gathered from ultrasequencing of meiofauna.

Behavioural context of multi-scale species distribution models assessed by radio-tracking

Incorporating ecological processes and animal behaviour into Species Distribution Models (SDMs) is difficult. In species with a central resting or breeding place, there can be conflict between the environmental requirements of the 'central place' and foraging habitat. We apply a multi-scale SDM to examine habitat trade-offs between the central place, roost sites, and foraging habitat in . Myotis nattereri. We validate these derived associations using habitat selection from behavioural observations of radio-tracked bats. A Generalised Linear Model (GLM) of roost occurrence using land cover variables with mixed spatial scales indicated roost occurrence was positively associated with woodland on a fine scale and pasture on a broad scale. Habitat selection of radio-tracked bats mirrored the SDM with bats selecting for woodland in the immediate vicinity of individual roosts but avoiding this habitat in foraging areas, whilst pasture was significantly positively selected for in foraging areas. Using habitat selection derived from radio-tracking enables a multi-scale SDM to be interpreted in a behavioural context. We suggest that the multi-scale SDM of . M. nattereri describes a trade-off between the central place and foraging habitat. Multi-scale methods provide a greater understanding of the ecological processes which determine where species occur and allow integration of behavioural processes into SDMs. The findings have implications when assessing the resource use of a species at a single point in time. Doing so could lead to misinterpretation of habitat requirements as these can change within a short time period depending on specific behaviour, particularly if detectability changes depending on behaviour. © 2011 Gesellschaft für ökologie.