Search results for "Trade-offs"
showing 10 items of 38 documents
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…
Environmental stress affects the expression of a carotenoid-based sexual trait in male zebra finches.
2007
SUMMARY Abiotic factors including thermal stress are suggested to exert constrains on sexual ornaments through trade-offs between sexual displays and physiological functions related to self-maintenance. Given the health properties of carotenoid pigments, carotenoid-based ornaments offer a relevant context in which to investigate the effect of environmental stress, such as ambient temperature, on the production and maintenance of secondary sexual traits and, also, to explore the proximate mechanisms shaping their expression. In this study, we exposed male zebra finches (Taeniopygia guttata) to environmental stress by exposing them to two temperature regimes (6 and 26°C) over a 4 week period.…
The evolution and ecology of multiple antipredator defences
2023
Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such “defence portfolios” that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of speci…
Matters of scale: positive allometry and the evolution of male dimorphisms
2005
J.L.T. was funded by a Biotechnology and Biological Sciences Research Council research fellowship, J.S.K. by the Academy of Finland, and N.R.L. by a Natural Environment Research Council research fellowship. The developmental independence of alternative phenotypes is key to evolutionary theories of phenotypic plasticity and the origins of diversity. Male dimorphisms associated with alternative reproductive tactics are widely cited examples of such facultative expression of divergent fitness optima. Current models for the evolution of male dimorphisms invoke a size-dependent threshold at which the phenotype is reprogrammed. We use predictions derived from allometric modeling to test for the e…
Managing boreal forests for the simultaneous production of collectable goods and timber revenues
2016
Timber Production is an economically important provisioning ecosystem service in forests, but is often in conflict with the provision of other ecosystem services. In multifunctional forestry, the production of timber and non-timber ecosystem services should coexist in the same landscape. To this end, we explored the capacity of a boreal landscape to simultaneously produce collectable goods − bilberry (Vaccimium myrtillus L.), cowberry (Vaccinium vitis-idaea L.) and cep (Boletus edulis Bull.) − alongside timber revenues. We also identified optimal forest management plans to achieve this. Furthermore, we analyzed trade-offs between collectable good yields and timber production, as well as bet…
A Multi-Criteria Decision Support System for Strategic Planning at the Swiss Forest Enterprise Level: Coping With Climate Change and Shifting Demands…
2021
Sustainable forest management plays a key role for forest biodiversity and the provisioning of ecosystem services (BES), including the important service of carbon sequestration for climate change mitigation. Forest managers, however, find themselves in the increasingly complex planning situation to balance the often conflicting demands in BES. To cope with this situation, a prototype of a decision support system (DSS) for strategic (long-term) planning at the forest enterprise level was developed in the present project. The DSS was applied at three case study enterprises (CSEs) in Northern Switzerland, two lowland and one higher-elevation enterprise, for a 50-year time horizon (2010 to 2060…
Multiple aspects of plasticity in clutch size vary among populations of a globally-distributed songbird.
2013
Plasticity in life-history characteristics can influence many ecological and evolutionary phenomena, including how invading organisms cope with novel conditions in new locations or how environmental change affects organisms in native locations. Variation in reaction norm attributes is a critical element to understanding plasticity in life history, yet we know relatively little about the ways in which reaction norms vary within and among populations. We amassed data on clutch size from marked females in eight populations of house sparrows (Passer domesticus) from North America and Europe. We exploited repeated measures of clutch size to assess both the extent of within-individual phenotypic …
Prenatal androgen exposure modulates cellular and humoral immune function of black-headed gull chicks
2005
Avian eggs contain considerable amounts of maternal yolk androgens, which have been shown to beneficially influence the physiology and behaviour of the chick. As androgens may suppress immune functions, they may also entail costs for the chick. This is particularly relevant for colonial species, such as the black-headed gull (Larus ridibundus), in which the aggregation of large numbers of birds during the breeding season enhances the risk of infectious diseases for the hatching chick.To test the effect of maternal yolk androgens on the chick's immune function, we experimentally manipulated, in a field study, yolk androgen levels within the physiological range by in ovo injection of either a…
Increased susceptibility to oxidative damage as a cost of accelerated somatic growth in zebra finches.
2007
1. Most animals do not grow at their maximal rate. This might appear puzzling because the early attainment of a large body size incurs several selective benefits, such as reduced risk of predation and earlier reproductive output. Several hypotheses have been suggested to explain this paradox. Among them, the cost due to high levels of oxidative stress, as the consequence of sustained metabolic activity during growth, has been put forward.
Senescence and longevity : from physiological mechanisms to evolutionary processes : studies in birds and mammals
2012
There is an incredible diversity of lifespan in the animal kingdom ranging from a few days for small gastrotrichs worms to several hundred of years for some bivalves or tortoises. This amazing diversity has long questioned biology researchers. The growing interest in the phenomenon of aging, mainly due to the increase in life expectancy in humans, has questioned researchers on processes that determine patterns of longevity and ageing. On the one hand, biomedical and biogerontological studies helped describe numerous cellular and physiological mechanisms related to aging. Among these mechanisms, oxidative stress has been identified as playing a major role, through life-time accumulation of d…