Search results for " Systematics."
showing 10 items of 4820 documents
Density‐dependent influence of male characters on mate‐locating efficiency and pairing success in the waterlouse Asellus aquaticus: an experimental s…
2005
Population density is likely to determine the form of competition in which males are engaged for access to females. At low density, scramble competition should be of paramount importance because of the low probability of encounter between males and females. Consequently, sexual selection should favour characters that allow rapid detection of females. Conversely, at high population density, sexual selection should favour attributes that raise the fighting ability of males because of the more frequent contacts between males. These general predictions were tested in this study for the precopulatory mate-guarding isopod, Asellus aquaticus. In this species, male-biased sexual dimorphisms are rep…
Behaviour of cyclic bank voles under risk of mustelid predation: do females avoid copulations?
1993
Mustelid odours have been shown to suppress breeding in captive bank voles (Clethrionomys glareolus) from cyclic populations (Ylonen 1989; Ylonen and Ronkainen 1994). The mechanism behind the suppression is unknown. Based on a series of behavioural trials and breeding experiments with pairs of bank voles in breeding condition, we suggest that the primary cause for breeding suppression is a change in female mating behaviour. Experimental female-male pairs (n=34) exposed to mustelid odour decreased their general activity compared to control pairs (n=34). When encountering males in behavioural trials, females exposed to stoat odour were more aggressive and actively avoided precopulatory behavi…
Sex ratio and spatial distribution of male and female Antennaria dioica (Asteraceae) plants
2011
Sex ratio, sex spatial distribution and sexual dimorphism in reproduction and arbuscular mycorrhizal colonisation were investigated in the dioecious clonal plant Antennaria dioica (Asteraceae). Plants were monitored for five consecutive years in six study plots in Oulanka, northern Finland. Sex ratio, spatial distribution of sexes, flowering frequency, number of floral shoots and the number and weight of inflorescences were recorded. In addition, intensity of mycorrhizal fungi in the roots was assessed. Both sexes flowered each year with a similar frequency, but the overall genet sex ratio was strongly female-biased. The bivariate Ripley’s analysis of the sex distribution showed that within…
Breeding system and conservation strategy of the extremely endangered Cistus carthaginensis Pau (Cistaceae) of Spain
2001
Cistus carthaginensis is one of the most endangered plants in Europe: at present there exist only a few individuals in Murcia and one in Valencia (SE and E Spain). To design an adequate conservation strategy able to avoid the extinction of this species, various aspects of its reproductive biology were studied. The extreme rarity of C. carthaginensis is not related to problems of development and/or fertility of pollen or ovules produced by the few existing specimens. Meiosis in the pollen mother cells is always regular and chromosome segregation is completely equilibrated in the male gametes. Pollen and ovule production is high and similar to that reported for other related species of Cistus…
Developmental speed affects ecological stoichiometry and adult fat reserves in Drosophila melanogaster
2020
Abstract The elemental composition of organisms belongs to a suite of functional traits that change during development in response to environmental conditions. However, associations between adaptive variations in developmental speed and elemental body composition are not well understood. We compared body mass, elemental body composition, food uptake and fat metabolism of Drosophila melanogaster male fruit flies in relation to their larval development speed. Slowly developing flies had higher body carbon concentration than rapidly developing and intermediate flies. Rapidly developing flies had the highest body nitrogen concentration, while slowly developing flies had higher body nitrogen lev…
Otter Lutra lutra predation on farmed and free‐living salmonids in boreal freshwater habitats
2002
In this paper we aim to define whether fish farms or stocked trout streams substantially contribute to the diet of otters Lutra lutra living in freshwater habitats of Mid-Finland. Diet was assessed using spraint analysis. We especially focused on areas with fish farms and stocked trout Salmo trutta streams (salmonid-rich habitat) and used ‘normal’ (salmonid-poor) habitats as control. Frequency of salmonid remains in spraints was significantly higher in salmonid-rich habitats than elsewhere in all seasons, the difference increasing from summer to winter. In salmonid-rich habitats, however, salmonid consumption was not strongly seasonal. Data from spraint collection indicated a shift in activ…
Food availability and the male's role in parental care in double-brooded TreecreepersCerthia familiaris
1996
The aim of this work was to examine differences in paternal and maternal care in a double-brooded, monogamous species, the Treecreeper Certhia familiaris, in relation to food availability. As a measure of parental care, we recorded the hourly feeding activity of parents when the nestlings from their first and second breeding attempts were 7 and 12 days old. Feeding frequency of the first brood increased with the age of the nestlings and also with the brood size when 12 days old. While the feeding activities of the females were similar with respect to the first and second broods, the males were less active and failed to provide any food to their nestlings in 15 cases out of 28 second broods.…
Biotechnological control methods against phytopathogenic bacteria in tomatoes
2019
THREE NEW SPECIES OF CHOREBUS FROM SPAIN (HYMENOPTERA: BRACONIDAE: ALYSIINAE)
2002
Chorebus affiniformis, C. dentisignatus and C. granulosus, three species of Dacnusini from Spain, are described as new and are compared with allied species of the genus. Keys for their discrimination are provided.
First record of the genus Syncrasis in Spain, with а redescription of Syncrasis (Eusyncrasis) talitzkii Tobias, 1986 (Hymenoptera: Braconidae: Alysii…
2011
The genus Syncrasis Foerster, 1862 as subgenus Eusyncrasis Tobias, 1986 is recorded for the first time in the fauna of Spain. A key to subgenera, and a detailed redescription of Syncrasis (Eusyncrasis) talitzkii Tobias, 1986 on the basis of Spanish material collected by а Malaise trap in the Alicante Province, are provided.