Search results for " Systematics."
showing 10 items of 4820 documents
Sex-specific effects of natural and sexual selection on the evolution of life span and ageing in Drosophila simulans
2014
Summary Variation in the strength of age-dependent natural selection shapes differences in ageing rates across species and populations. Likewise, sexual selection can promote divergent patterns of senescence across the sexes. However, the effects of these processes on the evolution of ageing have largely been considered independently, and interactions between them are poorly understood. We use experimental evolution to investigate how natural and sexual selection affect life span and ageing in Drosophila simulans. Replicate populations were evolved under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and at one of two temperatures, 25 °C (rela…
Urban forest soils harbour distinct and more diverse communities of bacteria and fungi compared to less disturbed forest soils.
2022
Anthropogenic changes to land use drive concomitant changes in biodiversity, including that of the soil microbiota. However, it is not clear how increasing intensity of human disturbance is reflected in the soil microbial communities. To address this issue, we used amplicon sequencing to quantify the microbiota (bacteria and fungi) in the soil of forests (n=312) experiencing four different land uses, national parks (set aside for nature conservation), managed (for forestry purposes), suburban (on the border of an urban area) and urban (fully within a town or city), which broadly represent a gradient of anthropogenic disturbance. Alpha diversity of bacteria and fungi increased with increasin…
Bedrock and soil geochemistry influence the content of chemical elements in wild edible mushrooms (Morchella group) from South Italy (Sicily)
2019
Chemical elements in the samples of wild edible mushrooms of the <em>Morchella</em> group collected from different unpolluted Sicilian sites was analyzed by the ICP-MS (method) to detect the content of their minerals and determine whether soil geology and geochemistry can influence the chemical composition in fungi. Results showed that the mushroom samples mainly contained a high concentration of K and P and a wide variety of minor and trace elements (V, Mo, Pb, Ce, Cs, Zr), including heavy metals. Statistical analysis showed that the mushrooms differed in their content of minor and trace elements based on the geological/geographic site of origin. Comparison with other studies s…
Ecologists overestimate the importance of predictor variables in model averaging: a plea for cautious interpretations.
2014
Abstract: Information-theory procedures are powerful tools for multimodel inference and are now standard methods in ecology. When performing model averaging on a given set of models, the importance of a predictor variable is commonly estimated by summing the weights of models where the variable appears, the so-called sum of weights (SW). However, SWs have received little methodological attention and are frequently misinterpreted. We assessed the reliability of SW by performing model selection and averaging on simulated data sets including variables strongly and weakly correlated to the response variable and a variable unrelated to the response. Our aim was to investigate how useful SWs are …
Variation in the Sizes of Chthamalid Barnacle Post-Settlement Cyprids on European Shores
2001
As part of a wider study on the settlement and recruitment of Chthamalus spp. in Europe, this study investigated whether chthamalid cyprids can be separated by length on a European scale. Variation in cyprid length with latitude and temporal variation at selected localities were also examined. The lengths of cyprids collected between 1996-1999 on nine rocky shores in Europe are reported. Elminius modestus cyprids were found only at Roscoff, NW France and could be distinguished due to their Carapace shape and length. They showed a unimodal length distribution, measuring between 450 and 625 mum, with no variation in length between the two sampling dates (1997 and 1998). Based on carapace shap…
Phylogeography of a Palaearctic sedentary passerine, the willow tit (Parus montanus)
2001
We analysed variation of the mitochondrial control region from willow tits through its Palaearctic distribution range. Although we found high amount of genetic variation (π=1.114%), there was almost no differentiation between subspecies or geographical localities. This may be because of a combination of several ecological and genetic factors, including a relatively homogenic habitat through the distribution range, lack of geographical barriers, high gene flow and a large long-term effective population size. On the contrary, in the songar tit, which is sometimes considered to be conspecific with the willow tit, the mitochondrial lineages seem to correlate with the geographical locality and a…
Conceptualizing ecosystem tipping points within a physiological framework
2017
Connecting the nonlinear and often counterintuitive physiological effects of multiple environmental drivers to the emergent impacts on ecosystems is a fundamental challenge. Unfortunately, the disconnect between the way “stressors” (e.g., warming) is considered in organismal (physiological) and ecological (community) contexts continues to hamper progress. Environmental drivers typically elicit biphasic physiological responses, where performance declines at levels above and below some optimum. It is also well understood that species exhibit highly variable response surfaces to these changes so that the optimum level of any environmental driver can vary among interacting species. Thus, specie…
Lymphatic vessels of the dura mater: a new discovery?
2015
Aspelund et al. discover the presence of a lymphatic vessel network in the dura mater of the mouse brain and show that these dural lymphatic vessels are important for the clearance of macromolecules from the brain.
Phylogenetic diversity and affiliation of tropical African ectomycorrhizal fungi
2022
Ectomycorrhizal fungi form a mutualistic symbiosis with plant roots, and are key for nutrient cycling in many ecosystems. Here we study the ectomycorrhizal fungal communities in the Oueme Superieur reserve forest in Benin (West Africa). We use phylogenetic methods to test if the species from the study site are closer to other tropical African species than to species from other regions. The Oueme Superieur community was represented by nine Operational Taxonomic Units in Amanitaceae, one in Boletaceae, one in Cantharellaceae, one in Cortinariaceae, two in Inocybaceae, fourteen in Russulaceae and three in Sclerodermataceae. Of these thirty-one Operational Taxonomic Units, twenty had no record …
Description and phylogenetic relationships of a new species of treefrog of theOsteocephalus buckleyispecies group (Anura: Hylidae)
2020
The Osteocephalus buckleyi species group is widely distributed in primary and secondary forests of the Amazon Basin and Guiana Region. Based on integrative analysis, including morphological and genetic data, we estimate the phylogenetic relationships and species boundaries among populations of the Osteocephalus buckleyi group from the Ecuadorian Amazon, focusing on the O. verruciger-O. cannatellai species complex. Our results uncovered the existence of one confirmed candidate species from Sangay National Park and one unconfirmed candidate species. Here, we describe the new species which is morphologically and ecologically distinct from other Osteocephalus species. The new species is unusual…