Search results for "Time"
showing 10 items of 12336 documents
Pairing context determines condition-dependence of song rate in a monogamous passerine bird.
2013
Condition-dependence of male ornaments is thought to provide honest signals on which females can base their sexual choice for genetic quality. Recent studies show that condition-dependence patterns can vary within populations. Although long-term association is thought to promote honest signalling, no study has explored the influence of pairing context on the condition-dependence of male ornaments. In this study, we assessed the influence of natural variation in body condition on song rate in zebra finches ( Taeniopygia guttata ) in three different situations: during short and long encounters with an unfamiliar female, and within heterosexual mated pairs. We found consistent individual diff…
Northward invasion of the parasitic deer ked ( Lipoptena cervi), is there geographical variation in pupal size and development duration?
2010
SUMMARYThe deer ked (Lipoptena cervi) is a common ectoparasite of cervids. During the last decades the species has rapidly invaded in northern Europe, especially in Finland, towards the north and increased its prevalence on the moose population. Consequently, during this rapid invasion the deer ked has faced more severe climatic conditions. We studied whether pupal size (measured as pupal weight) and pupal development duration of the deer ked varies along historical invasion zones and temperature zones towards north in Finland. Moreover, we explored possible size- and gender-dependent variation in pupal development duration. We divided wild-collected pupae in respect to their origin in two …
Avoiding perceived past resource use of potential competitors affects niche dynamics in a bird community
2014
Abstract. Background: Social information use is usually considered to lead to ecological convergence among involved con- or heterospecific individuals. However, recent results demonstrate that observers can also actively avoid behaving as those individuals being observed, leading to ecological divergence. This phenomenon has been little explored so far, yet it can have significant impact on resource use, realized niches and species co-existence. In particular, the time-scale and the ecological context over which such shifts can occur are unknown. We examined with a long-term (four years) field experiment whether experimentally manipulated, species-specific, nest-site feature preferences (sy…
Endocrine correlates of the breeding asynchrony between two Corsican populations of Blue tits (Parus caeruleus)
2004
International audience; Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the Wrst results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy diVerent oak habitats and are separated by only 25km. Despite their close proximity, they show a one-month diVerence in onset of egg laying, even after controlling for altitude. This micro-geographic diVerence in breeding date appears adaptive because both study populations raise chicks when food is most plentiful. In our study, males reached their maximum …
Co-variation between the intensity of behavioural manipulation and parasite development time in an acanthocephalan-amphipod system.
2010
8 pages; International audience; Pomphorhynchus laevis, a fish acanthocephalan parasite, manipulates the behaviour of its gammarid intermediate host to increase its trophic transmission to the definitive host. However, the intensity of behavioural manipulation is variable between individual gammarids and between parasite populations. To elucidate causes of this variability, we compared the level of phototaxis alteration induced by different parasite sibships from one population, using experimental infections of Gammarus pulex by P. laevis. We used a naive gammarid population, and we carried out our experiments in two steps, during spring and winter. Moreover, we also investigated co-variati…
The critical period of weed control in faba bean and chickpea in Mediterranean areas
2013
Weeds are often the major biological constraint to growing legume crops successfully, and an understanding of the critical period of weed control (CPWC) is important for developing environmentally sustainable weed management practices to prevent unacceptable yield loss. Therefore, we carried out two field experiments to identify the CPWC for two grain legume crops traditionally grown in Mediterranean areas: chickpea and faba bean. The experiments were conducted at two sites both located in the Sicilian inland (Italy). In chickpea, when weeds were left to compete with the crop for the whole cycle, the grain yield reduction was on average about 85% of the weed-free yield, whereas in faba bean…
Heat requirements for loquat fruit development may be assessed with a Beta model approach
2018
In Mediterranean areas, loquat trees (Eriobotrya japonica Lindl.) typically bloom in fall and fruits develop during the winter period, reaching their ripening in spring. So far, little interest has been driven towards models capable of estimating heat requirements for the accomplishment of fruit development in the winter period. In this work, we verified whether in Mediterranean areas the heat accumulation (GDH) needed for loquat fruit growth, may be precisely described using a Beta model, a flexible mathematical function which, in the past, has been successfully used in peach. BBCH phenological stages of ‘Algerie’ trees were recorded in two experimental sites: Palermo, Italy (38°04’N, 13°2…
Encapsulation of black mulberry microcuttings: studies on capsules and synthetic seeds
2017
The encapsulation technology for plant tissue culture can be an efficient tool to optimize the plant management systems and to preserve valuable plant germplasm. In this paper, two experiments were carried out to evaluate the encapsulation efficiency in mulberry (Morus nigra L.). In the first experiment, gel capsules were stored at 4°C for different times (0, 30, 90, 180 and 360 days). The highest percentage of shoot viability (82.5%) and regrowth (72.5%) was scored after 180 days of storage, with an average development of 2.5 shoots/capsule. The second experiment was aimed to point out an efficient protocol to turn the capsules of black mulberry in synthetic seeds ready to develop into who…
Going underground: short- and long-term movements may reveal the fossorial spatial ecology of an amphisbaenian
2021
[Background]: The movement and spatial ecology of an animal depends on its morphological and functional adaptations to its environment. In fossorial animals, adaptations to the underground life help to face peculiar ecological challenges, very different from those of epigeal species, but may constrain their movement ability.
Natural Selection Fails to Optimize Mutation Rates for Long-Term Adaptation on Rugged Fitness Landscapes
2008
The rate of mutation is central to evolution. Mutations are required for adaptation, yet most mutations with phenotypic effects are deleterious. As a consequence, the mutation rate that maximizes adaptation will be some intermediate value. Here, we used digital organisms to investigate the ability of natural selection to adjust and optimize mutation rates. We assessed the optimal mutation rate by empirically determining what mutation rate produced the highest rate of adaptation. Then, we allowed mutation rates to evolve, and we evaluated the proximity to the optimum. Although we chose conditions favorable for mutation rate optimization, the evolved rates were invariably far below the optimu…