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In European streams, native brown trout (Salmo trutta) feed primarily on aquatic prey but consume a higher proportion of terrestrial prey in sympatry with non-native brook trout (Salvelinus fontinalis). This is a rare example of diet convergence that may be associated with changes in diel activity or aggregation pattern by brown trout in sympatry. We recorded the activity and positions of brown trout from two origins and in two competition modes (allopatry versus sympatry, four combinations) placed in replicated stream enclosures for 29 days to test these hypotheses. Brown trout originating from or placed in sympatry were more diurnal and aggregated than those originating from or placed in allopatry. Changes in the diel activity of brown trout placed in a novel competition mode occurred progressively throughout the study. Thus, brown trout show strong behavioral flexibility in response to the non-native competitor and can revert to allopatric behavior when brook trout is removed from the system. These behavioral adjustments may have unsuspected effects on food webs and ecosystem functioning, which deserve further attention. Dans les cours d'eau europeens, les truites brunes (Salmo trutta) indigenes se nourrissent principalement de proies aquatiques, mais consomment une plus forte proportion de proies terrestres quand elles sont en sympatrie avec des ombles de fontaine (Salvelinus fontinalis) non indigenes. Il s'agit d'un rare exemple de convergence de regimes alimentaires qui pourrait etre associee a des changements de l'activite nycthemerale et du motif de regroupement par les truites brunes sympatriques. Nous avons enregistre l'activite et les emplacements de truites brunes de deux origines et pour deux modes de concurrence (allopatrie et sympatrie, quatre combinaisons) placees dans des enclos doubles en riviere pendant 29 jours pour verifier ces hypotheses. Les truites brunes d'origine sympatrique ou placees en sympatrie etaient plus diurnes et regroupees que celles d'origine allopatrique ou placees en allopatrie. Des changements de l'activite nycthemerale des truites brunes mises dans un nouveau mode de concurrence se sont produits graduellement au fil de l'etude. Ainsi, les truites brunes presentent une forte souplesse comportementale en reaction au concurrent non indigene et peuvent reprendre un comportement allopatrique quand les ombles de fontaine sont retires du systeme. Ces ajustements comportementaux pourraient avoir des effets insoupconnes sur les reseaux trophiques et le fonctionnement d'ecosystemes, ce qui merite plus d'attention., Introduction Biological invasions have important ecological and evolutionary consequences on native biodiversity (Strayer et al. 2006; Ehrenfeld 2010; Lowry et al. 2013). One of the most common and pervasive effects [...]

We combined habitat mapping, radio tracking of adults, redd mapping, and genetic parentage analysis on juveniles for 2 consecutive years to test eight predictions on the reproductive payoffs and individual features associated with space use tactics of anadromous Atlantic salmon (Salmo salar) in a natural population. Regarding payoffs, we found that (1) males settled in better habitat, visited more redds, and tended to get more mates than males settled in poorer habitat; (2) they also sired more offspring; (3) the latter effect was stronger in the first year, when redds were more aggregated; and (4) female reproductive success increased with habitat quality in their home range, especially in the first year. For individual features, (5) individuals that settled earlier in their home range had better habitat for juvenile production, but only in the first year; (6) females were less mobile than males, especially in the second year; (7) larger males did not settle in better habitats than smaller males; and (8) smaller males were not more mobile than larger males. Nous combinames la cartographie de l'habitat et des frayeres, le suivi radio des geniteurs et l'analyse de parente sur les alevins pendant deux annees pour tester huit predictions sur les gains et les caracteristiques individuelles associes aux tactiques spatiales dans une population de saumons de l'Atlantique (Salmo salar). Concernant les gains, nous trouvames que (1) les males etablis dans les meilleurs habitats visiterent plus de frayeres et eurent plus de partenaires; (2) ils engendrerent plus de descendance; (3) ce dernier effet fut plus marque quand les frayeres etaient plus agregees; et (4) le succes reproducteur des femelles augmentat avec la qualite d'habitat dans leur domaine vital, surtout lors de la premiere annee. Pour les caracteristiques individuelles, (5) les individus s'etablissant en premier dans leur domaine vital occuperent un habitat plus favorable pour la production de juveniles; (6) les femelles furent moins mobiles que les males, surtout lors de la deuxieme annee; (7) les plus grands males ne s'etablirent pas dans de meilleurs habitats que les petits; et (8) qui ne furent pas plus mobiles que les grands., Introduction The spatiotemporal distribution of resources imposes a selective pressure on many aspects of individual behavior: where to settle (Fretwell and Lucas 1969), how long to stay in a given [...]

When, how often and for how long organisms mate can have strong consequences for individual fitness and are crucial aspects of evolutionary ecology. Such determinants are likely to be of even greater importance in monandrous species and species with short adult life stages. Previous work suggests that mobility, a key dispersal‐related trait, may affect the dynamics of copulations, but few studies have investigated the impact of individual mobility on mating latency, copulation duration and oviposition latency simultaneously. In this paper, we monitored the copulation dynamics of 40 males and 40 females, as well as the oviposition dynamics of the females of the Large White butterfly Pieris brassicae, a facultative long‐distance disperser butterfly. Individuals from a breeding were selected to create a uniform distribution of mobility and we recorded the timing, number and duration of all copulations in a semiexperimental system. We showed that mobility, measured as the time spent in flight under stressful conditions (a proxy of dispersal tendency), correlates with all aspects of copulation dynamics: mobile males and females mated earlier and for shorter periods than less mobile individuals. In turn, late mating females increased the time between copulation and oviposition. These results feed the previously described mobility syndrome of P. brassicae, involving morphological and physiological characters, with life‐history traits. We suggest that the reduction of mating latency and copulation duration has an adaptive value in dispersing individuals, as their life expectancy might be shorter than that of sedentary individuals. [ABSTRACT FROM AUTHOR]