Aspects of the ecology of the spotted blindsnake,Typhlops punctatus punctatus in Port‐Harcourt,Nigeria

The ecology of the blindsnake, Typhlops punctatus punctatus in five selected study plots in the River Niger Delta (Port Harcourt, Nigeria) was investigated. A total of 207 specimens were collected, 43% occurring under stones, 30% under leaf litter and 15% under logs. The number of snakes found under cover objects was significantly influenced by the number of cover objects lifted up. GLM analysis revealed that there was no difference in terms of number of snakes observed, once the relative effect of the different number of cover objects lifted up was taken into account, either among study plots or among types of cover objects. These snakes appeared to have a strong affinity for loamy soils, with moisture content of 8–18%, high organic matter (1–6%) and slightly acid pH of 5.4–6.9. Stomach content analysis revealed that these snakes fed mainly upon ants and termites. A case of predation by the toad Bufo maculatus on a juvenile blindsnake was also reported.     

Age-Sex Analysis of Activity Budget,Diet, and Positional Behavior in <Emphasis Type="Italic">Alouatta caraya</Emphasis> in an Orchard Forest

Howlers (Alouatta spp.) spend more than half of the daytime resting and their diet consists predominantly of leaves. Associated with a general strategy of energy conservation, their positional behavior is characterized by quadrupedalism as the major locomotor mode, and sitting as the most common resting and feeding posture. However, researchers have sparse information on the degree to which age-sex classes fit the generic trends and the influence of habitat structure on them. We compare the activity budget, dietary composition, and positional behavior by age-sex or age classes in a group of black-and-gold howlers (Alouatta caraya) in a small orchard forest. We collected 26,474 behavioral records via instantaneous scan sampling over 1 yr. The main activity was resting (56%) and the diet comprised mainly leaves (82%); sitting was the most adopted feeding (61%) and resting (52%) posture, and walking was the most prevalent locomotor mode (38%). There are age-sex differences for all major behaviors. Whereas resting tended to increase with body size, moving decreased. We observed no difference in the consumption of major plant parts. There were ontogenetic differences in most positional behaviors. Sitting increased from infants to adults during feeding, whereas the opposite occurred for bridging and hanging. During resting, infants curled more and lay less than the other classes did, whereas adults engaged in more sitting. Adults and subadults walked more than individuals of other ages did; infants climbed and bridged more than others did; and, there were opposing trends in leaping and descending. Habitat structure is a partial explanation of the locomotor behavior of black-and-gold howlers.     

Reliability for detecting composition and changes of microbial communities by T-RFLP genetic profiling

Terminal restriction fragment length polymorphism (T-RFLP) analysis is commonly used for profiling microbial communities in various environments. However, it may suffer from biases during the analytic process. This study addressed the potential of T-RFLP profiles (1) to reflect real community structures and diversities, as well as (2) to reliably detect changing components of microbial community structures. For this purpose, defined artificial communities of 30 SSU rRNA gene clones, derived from nine bacterial phyla, were used. PCR amplification efficiency was one primary bias with a maximum variability factor of 3.5 among clones. PCR downstream analyses such as enzymatic restriction and capillary electrophoresis introduced a maximum bias factor of 4 to terminal restriction fragment (T-RF) signal intensities, resulting in a total maximum bias factor of 14 in the final T-RFLP profiles. In addition, the quotient between amplification efficiency and T-RF size allowed predicting T-RF abundances in the profiles with high accuracy. Although these biases impaired detection of real community structures, the relative changes in structures and diversities were reliably reflected in the T-RFLP profiles. These data support the suitability of T-RFLP profiling for monitoring effects on microbial communities.     

An ensemble model for predicting Rhopalosiphum padi abundance

A novel modeling method is proposed to predict the abundance of the main vector of barley yellow dwarf virus in autumn sown cereal crops. An ensemble model based on artificial neural networks (ANN) was developed to predict the number of Rhopalosiphum padi (L.) (Homoptera: Aphididae) caught in traps during the autumn flight period at Lincoln, Canterbury, New Zealand, over the period 1982–2003. Artificial neural networks were trained using historical weather data and aphid data collected from a suction trap. Model results were compared with those obtained using multiple regression (MR) models using the same independent variables. Both ANN and MR models were validated by leave‐one‐out validation, in other words, by sequentially jackknifing each year out of the data set, fitting a model to the remaining data, then using that model to predict the number of aphids for each jackknifed year. A linear ensemble of ANN models further improved the predictions and represented the trends in the number of aphids over the 22‐year period very well. The r² between the predicted and observed numbers of aphids for the ANN models changed from 0.68 to 0.83 using the linear ensemble model, but the ensemble approach did not change the prediction for the MR models. The absolute mean error (ABSME) of prediction was much lower for the ANN ensemble predictions compared to that for the MR models. The ABMSE for the ANN models dropped from 109 to 86 aphids compared to an ABMSE reduction from 245 to 220 aphids for the MR models. We discuss the potential for ensemble models for predicting insect abundance when long‐term historical data are available.     

Fine-scale adaptation in a clonal sea anemone

Local adaptation in response to fine-scale spatial heterogeneity is well documented in terrestrial ecosystems. In contrast, in marine environments local adaptation has rarely been documented or rigorously explored. This may reflect real or anticipated effects of genetic homogenization, resulting from widespread dispersal in the sea. However, evolutionary theory predicts that for the many benthic species with complex life histories that include both sexual and asexual phases, each parental habitat patch should become dominated by the fittest and most competitive clones. In this study we used genotypic mapping to show that within headlands, clones of the sea anemone Actinia tenebrosa show restricted distributions to specific habitats despite the potential for more widespread dispersal. On these same shores we used reciprocal transplant experiments that revealed strikingly better performance of clones within their natal rather than foreign habitats as judged by survivorship, asexual fecundity, and growth. These findings highlight the importance of selection for fine-scale environmental adaptation in marine taxa and imply that the genotypic structure of populations reflects extensive periods of interclonal competition and site-specific selection.     

Habitat factors affecting site occupancy and relative abundance of four-horned antelope

The four-horned antelope is endemic to the Indian sub-continent. It was formerly distributed widely in deciduous forests throughout its range, but the current distributional patterns of this low-density species are largely unknown and conservation efforts are hampered by the lack of information on species–habitat relationships. We investigated the habitat factors influencing four-horned antelope occurrence and abundance in Bandipur National Park, an important four-horned antelope conservation site in India. Detection/non-detection data, collected under a systematic sampling framework, were used to test a priori hypotheses incorporating covariates believed to influence occurrence and abundance. The best fitting models for four-horned antelope occurrence and relative abundance reveal that the tree-savanna deciduous habitat sub-type, characterized by relatively open habitats with a lower tree density and a high degree of deciduousness, is most preferred by the species. Four-horned antelope conservation efforts in Bandipur National Park and other reserves should be focused on areas typified by tree-savanna habitats. Four-horned antelope occurrence was negatively related to the alien weed Lantana camara . The prolific spread of this weed in Indian deciduous forests is a likely threat.     

Crossability relationships between Korean firs Abies koreana , A. nephrolepis and A. holophylla and some other representatives of the genus Abies

Artificial crossing experiments involving 3 Abies species native to Korean peninsula and 5 other representatives of Abies revealed a high hybridological affinity between Abies koreana and A. nephrolepis. Both these species are reproductively isolated from A. holophylla. All the three Korean species were found to exhibit incompatible relationships with the North American species A. concolor. The species A. holophylla and A. koreana differ also in their abilities to intercross with the Mediterranean firs. The former has been successfully crossed with A. nordmanniana, A. alba and A. cilicica exhibiting 19.1–55.3% crossability, whereas the latter produced filled seeds only with A. nordmanniana reaching 46.4% crossability. A considerable differentiation is postulated to exist between the pair of species A. koreana and A. nephrolepis on the one side and A. holophylla on the other side.     

Habitat Structure Affects Reproductive Success of the Rare Endemic Tree Syzygium mamillatum (Myrtaceae) in Restored and Unrestored Sites in Mauritius

Invasive alien plants affect the functioning of ecosystems by altering plant–animal interactions, such as pollination, which may impede natural regeneration of native plant species. In Mauritius, we studied the reproductive traits and pollination ecology of the rare endemic cauliflorous tree Syzygium mamillatum in a restored forest (all alien plant species removed) and an adjacent unrestored area (degraded by alien plants). Flowers of S. mamillatum were only visited by generalist bird species. Although the initial number of flower buds per tree in the restored forest tended to be higher than that of trees in the unrestored area, final fruit set and the number of seeds per fruit were lower in the restored forest. This corresponded with lower bird visitation rates in the restored area. Additionally, during budding stage, most trees were severely attacked by lepidopteran larvae, and bud loss through herbivory was higher in the restored forest. Thus, the difference in reproductive performance of S. mamillatum between the two localities was caused by contrasting herbivore attack and bird visitation behavior in restored and unrestored areas. Our findings illustrate the importance of restoration efforts in mimicking the original physical structure of habitats and interaction structure of interspecific relationships, and the difficulty of doing so given the imperfect knowledge and the reality that many native species have become locally extinct and replaced by exotic species.     

Integrating ecology with biogeography using landscape characteristics: a case study of subtidal habitat across continental Australia

Aim We aimed to redress a current limitation of local ecological studies (i.e. piecemeal information on specific taxa) by integrating existing ecological knowledge with quantifiable patterns in primary habitat (i.e. composition, distribution and cover) from local to continental scales. By achieving this aim, we sought to provide a biogeographical framework for the interpretation of variation in the ecology of, and threats to, subtidal rocky landscapes. Location The subtidal rocky coast of continental Australia, with longitudinal comparisons spanning > 4000 km of southern coast (115°03′ E–153°60′ E) between latitudes of 33°05′ S and 35°36′ S, and latitudinal comparisons across 26°40′ S to 37°08′ S of eastern Australia. Methods The frequency and size of patches of major benthic habitat were quantified to indicate contemporary function (ecology) and to establish patterns that may result from contrasting regional‐scale processes (biogeography). This was achieved by quantifying the composition and patchiness of key subtidal habitats across the continent and relating them to the known ecology of subsets of locations in each region. A nested design of several spatial scales (1000s, 100s, 10–1 km) was adopted to distinguish patterns at local through to biogeographical scales. Results We show biogeography (in terms of longitude and latitude) to have a fundamental influence on the patterns of abundance and composition of subtidal habitats across regional (1000s of kilometres) to local (10s of kilometres to metres) scales. Across the continent, the most fundamental patterns related to (1) the proportion of rock covered by kelp forests, as related to particular functional groups of herbivores, and (2) the small‐scale heterogeneity (metres) that characterizes these forests. Main conclusions We interpret these results within a framework of alternative processes known to maintain habitat heterogeneity across these regions (e.g. productivity versus consumption as shapers of habitat structure). These interpretations illustrate how regional differences in ecological patterns and processes can create contradictory outcomes for the management of natural resources. We suggest that researchers and managers of natural resources alike may benefit from understanding local issues (e.g. the effects of fishing and its synergies with water pollution) in their biogeographical contexts.     

Plant attributes determining the regional abundance of weeds on central European arable land

Aim Several recent studies have aimed to identify the biological, ecological and distributional attributes that determine the regional abundance of plant species. Here we aim to assess the relationships between regional abundance and species attributes in weeds on arable land. Location Czech Republic, central Europe. Methods The relationships between regional abundance and species attributes were studied with a data set of 381 weed species occurring on arable land in the Czech Republic. Regional species abundances were estimated from their occurrence frequency in vegetation plots distributed across the country. Using regression tree models, abundance was related to the biological traits, ecological indicator values, geographical distribution and habitat range of species. The models were calculated for the entire country and separately for weeds in cereals, root crops, lowlands and uplands. The effects of phylogenetic relatedness among species on their regional abundance were quantified and compared with the effects of species attributes. Results The results were similar for the whole data set and its particular subsets. Phylogeny explained 11.2–14.9% and species attributes 16.1–56.9% of the variation in regional abundance of weed species. Removal of the phylogenetic signal did not result in important changes in the effects of particular attributes. The most abundant species were those flowering in pre‐spring and early spring, adapted to low temperatures, relatively shade tolerant and with high nutrient requirements. The high regional abundance of these species positively correlated with their broad geographical (often circumpolar) distribution and broad habitat ranges. Main conclusions The regional abundance of weeds can, to some extent, be explained by their attributes. The most important attributes are those that enable weeds to grow and reproduce in the cool season when there is limited competition with crop plants, and those that are adaptations to growth in dense vegetation stands and highly productive habitats.