There is accumulating evidence that individuals leave their natal area and select a breeding habitat non-randomly by relying upon information about their natal and future breeding environments. This variation in dispersal is not only based on external information (condition dependence) but also depends upon the internal state of individuals (phenotype dependence). As a consequence, not all dispersers are of the same quality or search for the same habitats. In addition, the individual's state is characterized by morphological, physiological or behavioural attributes that might themselves serve as a cue altering the habitat choice of conspecifics. These combined effects of internal and external information have the potential to generate complex movement patterns and could influence population dynamics and colonization processes. Here, we highlight three particular processes that link condition-dependent dispersal, phenotype-dependent dispersal and habitat choice strategies: (1) the relationship between the cause of departure and the dispersers' phenotype; (2) the relationship between the cause of departure and the settlement behaviour and (3) the concept of informed dispersal, where individuals gather and transfer information before and during their movements through the landscape. We review the empirical evidence for these processes with a special emphasis on vertebrate and arthropod model systems, and present case studies that have quantified the impacts of these processes on spatially structured population dynamics. We also discuss recent literature providing strong evidence that individual variation in dispersal has an important impact on both reinforcement and colonization success and therefore must be taken into account when predicting ecological responses to global warming and habitat fragmentation.

Summary1. There is growing evidence that dispersal is highly phenotypically plastic, i.e. that dispersal is condition-dependent. In the common lizard, dispersal has even been shown to be in¯uenced by the maternal environment during pregnancy. Juveniles in good condition or issued from mothers in good condition disperse earlier or in higher numbers. 2. We hypothesized that plasma corticosterone was the proximate mechanism by which condition and dispersal are linked, and tested this by manipulating the level of circulating corticosterone in pregnant females of the common lizard. 3. After parturition, we measured juvenile attractiveness towards the mother and juvenile dispersal of corticosterone (B) and placebo (P) implanted females. 4. Ospring of B females did disperse in lower number than those of P females. B ospring were also more attracted by the mother's odour than P ospring. 5. In quite a few cases, the behavioural response of juveniles was dependent on the interaction between the hormonal treatment and the mother snout±vent length or condition (body weight corrected for snout±vent length). 6. Corticosterone constitutes therefore one of the proximate mechanisms involved in the prenatal control of juvenile dispersal in this species. Along with other results, it is proposed that prenatal control of dispersal has evolved in order to avoid competition between mothers and their ospring.

Summary 1.Integrative studies on ageing patterns in multiple traits of organisms are challenging and rare in free-living populations. However, developing integrative approaches could prove useful to understanding ageing patterns as causes of age variations are diverse, with conflicting or related actions. Accordingly, we investigated age variation of multiple aspects in the common lizard Lacerta (Zootoca) vivipara. 2. In a wild population of common lizards, we studied five fitness components, three physiological traits (cell-mediated immunity, corticosterone level, resting metabolic rate), and controlled for individual and environmental heterogeneities. To quantify ageing patterns in fitness, we used individual-based data collected over 14 years (18 684 captures, 892 reproductive events). 3. Ageing patterns were found in multiple aspects. They provided evidence for female maturation early in adulthood (access to reproduction, litter size), followed by senescence in female reproduction (litter success) and survival. In parallel to senescence, a pattern of terminal investment enhanced offspring quality (offspring body size, offspring corpulence, litter success). Ageing patterns involved physiology with higher metabolic rate and T cell-mediated immune response in old females. 4. Several ageing patterns were dependent on environmental and individual characteristics (habitat, year, sex, body size). Interestingly, senescence occurred only in females with a high reproductive effort early in life. Rarely showed, this trade-off between early and late-life performances is expected under the antagonistic pleiotropy and disposable soma theories of senescence. 5. Overall, this study emphasizes the interest of integrative studies to investigate the multifaceted process of ageing.

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