Search results for "adaptation"
showing 10 items of 1775 documents
Body shape differentiation at global and local geographic scales in the invasive cichlid Oreochromis mossambicus
2012
The Mozambique tilapia Oreochromis mossambicus (Teleostei, Cichlidae) has been transplanted worldwide during the 20th century, and now belongs to the list of the most invasive species. Using a geometric morphometric approach, we describe body shape differentiation among 15 populations from native (Mozambique) and invaded (New Caledonia and Guadeloupe) ranges. A dominant phylogeographic signal is detected, despite the broad range of environmental conditions at the local scale. This result suggests that phylogeographic background rather than phenotypic plasticity responding to environmental variation constitutes the main factor correlated with shape divergence. This could result from successi…
Transparency reduces predator detection in chemically protected clearwing butterflies
2018
Abstract1. Predation is an important selective pressure and some prey have evolved warning colour signals advertising unpalatability (i.e. aposematism) as an antipredator strategy. Unexpectedly, some butterfly species from the unpalatable tribe Ithomiini possess transparent wings, an adaptation rare on land but common in water where it helps avoiding predator detection.2. We tested if transparency of butterfly wings was associated with decreased detectability by predators, by comparing four butterfly species exhibiting different degrees of transparency, ranging from fully opaque to largely transparent. We tested our prediction using using both wild birds and humans in behavioural experiment…
VARIATION BETWEEN POPULATIONS AND LOCAL ADAPTATION IN ACANTHOCEPHALAN-INDUCED PARASITE MANIPULATION
2010
Many trophically transmitted parasites manipulate their intermediate host phenotype, resulting in higher transmission to the final host. However, it is not known if manipulation is a fixed adaptation of the parasite or a dynamic process upon which selection still acts. In particular, local adaptation has never been tested in manipulating parasites. In this study, using experimental infections between six populations of the acanthocephalan parasite Pomphorhynchus laevis and its amphipod host Gammarus pulex, we investigated whether a manipulative parasite may be locally adapted to its host. We compared adaptation patterns for infectivity and manipulative ability. We first found a negative eff…
Variability and cryptic heteromorphism of Ambrosia artemisiifolia seeds: What consequences for its invasion in France
2007
International audience; Background and Aims:Ambrosia artemisiifolia is a ruderal weed introduced from North America to Europe. It produces large amount of achenes which are highly heterogeneous in size. Due to the preponderant role of propagules in invasive plant processes, the achene mass variability related to germination, dispersal strategy and life history traits of offspring were investigated within this species. Methods:The variability in achene mass was quantified among six populations sampled in different habitats. The effects of achene mass variation on germination were studied. The percentages of floating and non-floating achenes were evaluated in the studied populations. The cons…
Long-term changes in autumn migration dates at the Strait of Gibraltar reflect population trends of soaring birds
2016
A growing body of work shows that climate change is the cause of a number of directional shifts in the spring phenology of migratory birds. However, changes in autumn phenology are well studied and their consistency across species, as well as their link with population trends, remains uncertain. We investigate changes in the autumn migration dates of 11 species of soaring birds over the Strait of Gibraltar over a 16-year period. Using models corrected for phylogeny, we assessed whether ecological and morphological characteristics, as well as population trends, account for interspecific shifts in migration times. We recorded different phenological changes in different periods of the migratio…
Condition-dependent ecdysis and immunocompetence in the amphipod crustacean, Gammarus pulex.
2010
The exoskeleton of arthropods forms an efficient protection against pathogens, but this first line of defence is periodically weakened during ecdysis, increasing the opportunity for surrounding pathogens to invade the body cavity. Since the richness of pathogens in the environment can be spatially and temporally variable, arthropods may have a fitness advantage in moulting in a place and time of low infection risk. Consistent with this hypothesis, we found that the amphipod crustacean, Gammarus pulex , exhibits temporal adjustment of the moult cycle in response to elevated risks of infection. Interestingly, this phenomenon is variable between two populations and independent of levels of im…
Responses of a native plant species from invaded and uninvaded areas to allelopathic effects of an invader
2019
Invaders exert new selection pressures on the resident species, for example, through competition for resources or by using novel weapons. It has been shown that novel weapons aid invasion but it is unclear whether native species co‐occurring with in‐ vaders have adapted to tolerate these novel weapons. Those resident species which are able to adapt to new selective agents can co‐occur with an invader while others face a risk of local extinction. We ran a factorial common garden experiment to study whether a native plant species, Anthriscus sylvestris, has been able to evolve a greater tolerance to the allelochemicals exerted by the invader, Lupinus polyphyllus. Lupinus polyphyllus produces …
Evolution of life-history traits and mating strategy in males: a case study on two populations of a Drosophila parasitoid.
2016
10 pages; International audience; Abiotic and biotic factors affect life-history traits and lead populations to exhibit different behavioural strategies. Due to the direct link between their behaviour and fitness, parasitoid females have often been used to test the theories explaining these differences. In male parasitoids, however, such investigations are vastly understudied, although their mating strategy directly determines their fitness. In this study, we compared the pattern of life history traits and the mating strategy of males in two populations of the Drosophila parasitoid Asobara tabida, exposed to different biotic and abiotic conditions, with the major difference being that one o…
Habitat associations drive species vulnerability to climate change in boreal forests
2016
Species climate change vulnerability, their predisposition to be adversely affected, has been assessed for a limited portion of biodiversity. Our knowledge of climate change impacts is often based only on exposure, the magnitude of climatic variation in the area occupied by the species, even if species sensitivity, the species ability to tolerate climatic variations determined by traits, plays a key role in determining vulnerability. We analyse the role of species’ habitat associations, a proxy for sensitivity, in explaining vulnerability for two poorly-known but species-rich taxa in boreal forest, saproxylic beetles and fungi, using three IPCC emissions scenarios. Towards the end of the 21…
Social process of adaptation to environmental changes: How eastern african societies intervene between crops and climate
2014
Abstract Studies on climate change can only be conducted on a long time scale, and observing how societies adapt their sowing practices to climate variability is challenging and costly. As an alternative, a space and time substitution design was used, changes in space corresponding to that induced in time by environmental change. On the eastern slope of Mount Kenya, the Tharaka community, originating from the lowlands (750 m), moved up to the midlands (950 m) with their lowland-adapted resources, whereas the Mwimbi, originating from wetter upland (1100 m), moved down to the midlands with their highland-adapted genetic resources. A weather station was installed at 950 and 1100 m, and a logis…