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Within-individual Variation (within-individual + variation)
Selected AbstractsRepeatability of dispersal behaviour in a common dwarf spider: evidence for different mechanisms behind short- and long-distance dispersalECOLOGICAL ENTOMOLOGY, Issue 2 2009DRIES BONTE Abstract 1.,The response of dispersal towards evolution largely depends on its heritability for which upper limits are determined by the trait's repeatability. 2.,In the Linyphiid spider E. atra, we were able to separate long- and short-distance dispersal behaviours (respectively ballooning and rappelling) under laboratory conditions. By performing repeated behavioural trials for females, we show that average dispersal trait values decrease with increasing testing days. By comparing mated and unmated individuals during two periods (before and after mating for the mated group, and the same two periods for the unmated group), we show that mating has no effect on the mean displayed dispersal behaviour or its within-individual variation. Repeatabilities were high and consistent for ballooning motivation, but not for rappelling. 3.,Ballooning motivation can be regarded as highly individual-specific behaviour, while general pre-dispersal and rappelling behaviours showed more individual variation. Such difference in repeatability between long- and short-distance dispersal suggests that short- and long-distance dispersal events are triggered by different ecological and evolutionary mechanisms. [source] High within-individual variation in total mercury concentration in seabird feathersENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2008Alexander L. Bond Abstract To our knowledge, no rigorous assessment of the variation in mercury concentrations within individual seabirds has been made using multiple body feathers. We analyzed five feathers from individual Arctic terns (Sterna paradisaea Pontoppidan), common terns (Sterna hirundo L.), and Leach's storm-petrels (Oceanodroma leucorhoa Veillot) and found levels of within-individual variability higher than population or time-series variation. Using a randomization procedure, we found a large range of possible mercury concentrations if only one feather per individual had been sampled. Researchers should report within-individual variability in future studies. [source] Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populationsMOLECULAR ECOLOGY, Issue 24 2009ANDREW D. FOOTE Abstract Ecological divergence has a central role in speciation and is therefore an important source of biodiversity. Studying the micro-evolutionary processes of ecological diversification at its early stages provides an opportunity for investigating the causative mechanisms and ecological conditions promoting divergence. Here we use morphological traits, nitrogen stable isotope ratios and tooth wear to characterize two disparate types of North Atlantic killer whale. We find a highly specialist type, which reaches up to 8.5 m in length and a generalist type which reaches up to 6.6 m in length. There is a single fixed genetic difference in the mtDNA control region between these types, indicating integrity of groupings and a shallow divergence. Phylogenetic analysis indicates this divergence is independent of similar ecological divergences in the Pacific and Antarctic. Niche-width in the generalist type is more strongly influenced by between-individual variation rather than within-individual variation in the composition of the diet. This first step to divergent specialization on different ecological resources provides a rare example of the ecological conditions at the early stages of adaptive radiation. [source] Inter-annual variation and information content of melanin-based coloration in female Eurasian kestrelsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009PABLO VERGARA Competition for resources (e.g. mates or food) is the main evolutionary explanation for conspicuous ornaments in males, although this idea is not generalized in females. Whether or not the expression of melanic coloration is dependent on environmental conditions remains controversial. We studied three different melanin-based female traits in the Eurasian kestrel Falco tinnunculus, a sexually dichromatic species, for a period of 10 years: grey coloration in rump and tail and the width of the black subterminal tail band. We analysed these traits for within-individual variation among years, as well as their possible link with indices of quality, such as age, body size, and breeding performance. The results obtained demonstrate that female melanin-based coloration increased from yearlings to adults. In addition, the expression of female rump coloration covaried positively with the environmental conditions in the previous year (i.e. measured as clutch size at population level). Finally, we found a positive correlation between grey rump coloration and clutch size. These results suggest that the expression of rump coloration, a melanin-based trait, is environmentally constrained, and we propose that this character could function as an indicator of individual quality in female Eurasian kestrels. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 781,790. [source] |