Search results for "81"
showing 10 items of 2468 documents
Ecological Stoichiometry of Bumblebee Castes, Sexes, and Age Groups
2021
Ecological stoichiometry is important for revealing how the composition of chemical elements of organisms is influenced by their physiological functions and ecology. In this study, we investigated the elemental body composition of queens, workers, and males of the bumblebee Bombus terrestris, an important pollinator throughout Eurasia, North America, and northern Africa. Our results showed that body elemental content differs among B. terrestris castes. Young queens and workers had higher body nitrogen concentration than ovipositing queens and males, while castes did not differ significantly in their body carbon concentration. Furthermore, the carbon-to-nitrogen ratio was higher in ovipositi…
Politically-Built Floods. The Chone Water Megaproject in Ecuador
2018
La construcción e implementación del megaproyecto hídrico Chone (Costa ecuatoriana) ha sido legitimada como medio para promover el desarrollo de la ciudad, pero ha inundado y transformado territorios rurales campesinos de manera permanente. El discurso utilitario en torno al ‘beneficio de las mayorías’ urbanas ha justificado el proyecto, en desmedro de la presumida ‘minoría subdesarrollada’ en el área rural. Durante la implementación del megaproyecto, los campesinos han sido presentados como ‘atrasados’ y ‘pre-modernos’; alejados de los imaginarios urbanos modernos acordes con la noción oficial de progreso y desarrollo. Los hacedores de política presentan el riesgo de inundaciones sólo como…
Socioeconomic differences in selected dietary habits among Norwegian 13-14 year-olds : a cross-sectional study
2014
Background: Social inequalities in health are a major and even growing problem in all European countries.; Objective: The aim of the present study was to describe 1) differences in dietary habits among Norwegian adolescents by gender and socioeconomic status; 2) differences in self-reported knowledge of dietary guidelines among their parents according to socioeconomic status. Design: In 2012, a cross-sectional study where students filled in a web-based food frequency questionnaire at school was conducted in nine lower secondary schools in Vest-Agder County, Norway. Socioeconomic status (SES) and knowledge of dietary guidelines were obtained from the parents using a web-based questionnaire. …
The natural history of Echinorhynchus bothniensis Zdzitowiecki and Valtonen, 1987 (Acanthocephala) in a high Arctic lake.
2015
The acanthocephalan Echinorhynchus bothniensis Zdzitowiecki and Valtonen, 1987 differs from most other species in the genus Echinorhynchus Zoega in Muller, 1776 by infecting mysids (order Mysida) instead of amphipods (order Amphipoda) as intermediate hosts. Here we report on the occurrence of E. bothniensis in mysids (Mysis segerstralei Audzijonytė et Vainola) and in its fish definitive hosts in a high Arctic lake. Out of 15 907 sampled mysids, 4.8% were infected with a mean intensity of 1.05 worms (range 1-5), although there was notable variation between samples taken in different years and sites. Larger mysids appear more likely to be infected. Of five fish species sampled, charr,Salvelin…
Can a snow structure model estimate snow characteristics relevant to reindeer husbandry?
2014
Snow affects foraging conditions of reindeer e.g. by increasing the energy expenditures for moving and digging work or, in contrast, by making access of arboreal lichen easier. Still the studies concentrating on the role of the snow pack structure on reindeer population dynamics and reindeer management are few. We aim to find out which of the snow characteristics are relevant for reindeer in the northern boreal zone according to the experiences of reindeer herders and is this relevance seen also in reproduction rate of reindeer in this area. We also aim to validate the ability of the snow model SNOWPACK to reliably estimate the relevant snow structure characteristics. We combined meteorolog…
Curvilinear interspecific density-range size relationship in small mammals in Finland
2013
ABSTRACTAim Macroecological patterns have mainly been depicted as atemporal, withexisting research covering only short time periods. One fundamental pattern inmacroecology is the interspecific relationship between local abundance andregional range size, which is generally considered to be positively linear. Here,we examine structural details of the relationship between abundance and rangesize in cyclic populations of small mammals and its long-term temporal varia-tion.Location Finland.Methods We analysed 39 years of trapping data of Rodentia and Soricomor-pha collected in field and forest habitats across Finland. Abundance was mea-sured as the mean population density of individuals, and range…
Monitoring fungal biodiversity – towards an integrated approach
2012
Biodiversity information databases and platforms have seen considerable progress in recent years. They have a high potential in conservation science in general, but may be even more revolutionary in relation to poorly known species groups such as fungi, whose practical conservation work has been jeopardised by scattered and poorly controlled information. We review the tradition of collecting information on species occurrences in mycology and discuss the characteristics of the present fungal biodiversity information databases. With a special focus on population trend monitoring of fruit body producing macrofungi, we emphasise several unrealised opportunities of these databases and point out …
Population-level consequences of risky dispersal
2014
Achieving sufficient connectivity between populations is essential for persistence, but costs of dispersal may select against individual traits or behaviours that, if present, would improve connectivity. Existing dispersal models tend to ignore the multitude of risks to individuals: while many assess the effect of mortality costs, there is also a risk of failing to find new habitat, especially when the entire inhabitable area remains both small and fragmented. There are few known rules governing whether individuals evolve to disperse more, or less, than what is ideal for population connectivity and persistence. Here we aim to fill this gap, while also noting that evolution might not only pr…
The joint emergence of group competition and within-group cooperation
2015
Abstract Between-group conflict and within-group cooperation can be seen as two sides of the same coin, coevolving in a group-structured population. There is strong support for between-group competition facilitating the evolution of human cooperative tendencies, yet our understanding of how competition arises is less clear. We show that groups of randomly assembled individuals spontaneously engage in costly group competition, and that decisions promoting between-group conflict are associated with high levels of within-group cooperation. Remarkably, when groups were given the possibility to compete against other groups, net earnings for individuals were higher than when groups were not allow…
Natural recruitment contributes to high densities of grass carp Ctenopharyngodon idella (Valenciennes, 1844) in Western Europe
2015
Introductions of grass carp, well known for their potentially negative ecosystem effects, have been performed in several countries around the world. As the species was considered unable to reproduce naturally under non-native environmental conditions, little attention was initially given to its invasive potential. We studied an area in northern-Italy where, contrary to expectations, introductions that were performed in the early 80s still exert a considerable pressure on aquatic macrophytes. In order to reveal whether the observed population dynamics are the result of natural events or stocking we analysed the density, age- and size-structure of the grass carp population and the migration p…