RESUMEN
Individual specialisations in behaviour are predicted to arise where divergence benefits fitness. Such specialisations are more likely in heterogeneous environments where there is both greater ecological opportunity and competition-driven frequency dependent selection. Such an effect could explain observed differences in rates of individual specialisation in habitat selection, as it offers individuals an opportunity to select for habitat types that maximise resource gain while minimising competition; however, this mechanism has not been tested before. Here, we use habitat selection functions to quantify individual specialisations while foraging by black-legged kittiwakes Rissa tridactyla, a marine top predator, at 15 colonies around the United Kingdom and Ireland, along a gradient of environmental heterogeneity. We find support for the hypothesis that individual specialisations in habitat selection while foraging are more prevalent in heterogeneous environments. This trend was significant across multiple dynamic habitat variables that change over short time-scales and did not arise through site fidelity, which highlights the importance of environmental processes in facilitating behavioural adaptation by predators. Individual differences may drive evolutionary processes, and therefore these results suggest that there is broad scope for the degree of environmental heterogeneity to determine current and future population, species and community dynamics.
Asunto(s)
Charadriiformes , Ecosistema , Animales , Reino UnidoRESUMEN
Environmental heterogeneity shapes the uneven distribution of resources available to foragers, and is ubiquitous in nature. Optimal foraging theory predicts that an animal's ability to exploit resource patches is key to foraging success. However, the potential fitness costs and benefits of foraging in a heterogeneous environment are difficult to measure empirically. Heterogeneity may provide higher-quality foraging opportunities, or alternatively could increase the cost of resource acquisition because of reduced patch density or increased competition. Here, we study the influence of physical environmental heterogeneity on behaviour and reproductive success of black-legged kittiwakes, Rissa tridactyla. From GPS tracking data at 15 colonies throughout their British and Irish range, we found that environments that were physically more heterogeneous were associated with longer trip duration, more time spent foraging while away from the colony, increased overlap of foraging areas between individuals and lower breeding success. These results suggest that there is greater competition between individuals for finite resources in more heterogeneous environments, which comes at a cost to reproduction. Resource hotspots are often considered beneficial, as individuals can learn to exploit them if sufficiently predictable. However, we demonstrate here that such fitness gains can be countered by greater competition in more heterogeneous environments.
Asunto(s)
Conducta Animal , Charadriiformes/fisiología , Ecosistema , Animales , Cruzamiento , Conducta Alimentaria , Irlanda , Reproducción , Factores de Tiempo , Reino UnidoRESUMEN
Highly connected networks generally improve resilience in complex systems. We present a novel application of this paradigm and investigated the potential for anthropogenic structures in the ocean to enhance connectivity of a protected species threatened by human pressures and climate change. Biophysical dispersal models of a protected coral species simulated potential connectivity between oil and gas installations across the North Sea but also metapopulation outcomes for naturally occurring corals downstream. Network analyses illustrated how just a single generation of virtual larvae released from these installations could create a highly connected anthropogenic system, with larvae becoming competent to settle over a range of natural deep-sea, shelf and fjord coral ecosystems including a marine protected area. These results provide the first study showing that a system of anthropogenic structures can have international conservation significance by creating ecologically connected networks and by acting as stepping stones for cross-border interconnection to natural populations.