Male Seychelles warblers use territory budding to maximize lifetime fitness in a saturated environment

In cooperatively breeding species, helping at the nest and budding off part of the natal territory have been advanced as strategies to increase fitness in an environment that is saturated with territories. The importance of helping or territory budding as a determinant of lifetime reproductive success (LRS) has been debated because the potential benefits of both strategies could not be separated. Here we test the causes and the immediate and future fitness consequences of single dispersal decisions taken by male Seychelles warblers (Acrocephalus sechellensis). Males breeding in high-quality territories (high food abundance) have significantly higher LRS than similar-aged males budding off part of the parental territory. Initially, budders have a low reproductive success (because of limited food resources or absence of a breeding partner). However, they have a long life span and inherit high-quality territories through site dominance, by which they gain higher LRS than breeders on low-quality territories, helpers, or floaters. Experimental creation of male breeding territory vacancies showed that most young males became budders because of intense competition for high-quality territories. The translocation of warblers to the previously unoccupied Aride Island shows that males behave according to the expected fitness benefits of each dispersal strategy. In the absence of competition for territories on Aride, all young males bred in high-quality territories. However, after saturation of high-quality habitat with territories, most males became budders rather than breeders on low-quality habitat, helpers, or floaters

Retained non-adaptive plasticity:gene flow or small inherent costs of plasticity?

Question: Do clams from populations not exposed to a predator retain the ability to respond to that predator??Motivation: If maintaining the potential for phenotypic plasticity involves a significant cost. plasticity should be selected against in constant environments.Background: Clams of the species Macoma balthica (a burrowing bivalve) respond to shore crabs by burrowing deeper in the sediment. Norwegian M. balthica are not exposed to crabs naturally whereas Dutch M. balthica are naturally exposed to variable crab densities.Sites: Collection: the Balsfjord near Tromso, Norway, and the Wadden Sea near Harlingen, The Netherlands. Holding tanks: outdoor basins with a continuous flow of unfiltered water from the Wadden Sea.Method: We introduced a mixture of clams from both sites into experimental aquaria with a thick layer of sandy sediment. Twelve aquaria contained one shore crab; twelve had none. We measured burrowing depth 7 days after the start of each experiment.Result: Clams from the two sites show similar burrowing responses after exposure to predatory crabs, supporting the hypothesis that maintaining the potential for plasticity costs very little.</p

Interference between the sexes in foraging bar-tailed godwits Limosa lapponica

Sexual size dimorphism is common in many bird species. A consequence of sexual size dimorphism is that the larger sex has larger food requirements, and also that it might be dominant over the smaller sex. We studied the foraging behaviour of Bar-tailed Godwits Limosa lapponica, a highly sexually size dimorphic species. Our interest is in intersexual competition and its consequences for habitat use. Male and female Bar-tailed Godwits were distributed non-randomly over the intertidal foraging areas. Males were concentrated on exposed mud flats, while females occurred more along the waterline. Also within these habitat types, the sexes associated with same-sex individuals. Males were more susceptible to intraspecific kleptoparasitism than females, which we suggest is the cause of the unequal spatial distribution of male and female Bar-tailed Godwits. Females seem to monopolise the better quality foraging areas, leaving males the rest

Interference between the sexes in foraging bar-tailed godwits Limosa lapponica

Sexual size dimorphism is common in many bird species. A consequence of sexual size dimorphism is that the larger sex has larger food requirements, and also that it might be dominant over the smaller sex. We studied the foraging behaviour of Bar-tailed Godwits Limosa lapponica, a highly sexually size dimorphic species. Our interest is in intersexual competition and its consequences for habitat use. Male and female Bar-tailed Godwits were distributed non-randomly over the intertidal foraging areas. Males were concentrated on exposed mud flats, while females occurred more along the waterline. Also within these habitat types, the sexes associated with same-sex individuals. Males were more susceptible to intraspecific kleptoparasitism than females, which we suggest is the cause of the unequal spatial distribution of male and female Bar-tailed Godwits. Females seem to monopolise the better quality foraging areas, leaving males the rest

Interference between the sexes in foraging bar-tailed godwits Limosa lapponica

Sexual size dimorphism is common in many bird species. A consequence of sexual size dimorphism is that the larger sex has larger food requirements, and also that it might be dominant over the smaller sex. We studied the foraging behaviour of Bar-tailed Godwits Limosa lapponica, a highly sexually size dimorphic species. Our interest is in intersexual competition and its consequences for habitat use. Male and female Bar-tailed Godwits were distributed non-randomly over the intertidal foraging areas. Males were concentrated on exposed mud flats, while females occurred more along the waterline. Also within these habitat types, the sexes associated with same-sex individuals. Males were more susceptible to intraspecific kleptoparasitism than females, which we suggest is the cause of the unequal spatial distribution of male and female Bar-tailed Godwits. Females seem to monopolise the better quality foraging areas, leaving males the rest

Adaptive and maladaptive consequences of “matching habitat choice:” lessons from a rapidly-evolving butterfly metapopulation

Relationships between biased dispersal and local adaptation are currently debated. Here, I show how prior work on wild butterflies casts a novel light on this topic. “Preference” is defined as the set of likelihoods of accepting particular resources after encountering them. So defined, butterfly oviposition preferences are heritable habitat adaptations distinct from both habitat preference and biased dispersal, but influencing both processes. When a butterfly emigrates after its oviposition preference begins to reduce realized fecundity, the resulting biased dispersal is analogous to that occurring when a fish emigrates after its morphological habitat adaptations reduce its feeding rate. I illustrate preference-biased dispersal with examples from metapopulations of Melitaea cinxia and Euphydryas editha. E. editha were feeding on a well-defended host, Pedicularis, when humans created patches in which Pedicularis was killed and a less-defended host, Collinsia, was rendered phenologically available. Patch-specific natural selection favoured oviposition on Collinsia in logged (“clearing”) patches and on Pedicularis in undisturbed open forest. Quantitative variation in post-alighting oviposition preference was heritable, and evolved to be consistently different between patch types. This difference was driven more by biased dispersal than by spatial variation of natural selection. Insects developing on Collinsia in clearings retained adaptations to Pedicularis in clutch size, geotaxis and oviposition preference, forcing them to choose between emigrating in search of forest habitats with Pedicularis or staying and failing to find their preferred host. Insects that stayed suffered reduction of realized fecundity after delayed oviposition on Collinsia. Those that emigrated suffered even greater fitness penalty from consistently low offspring survival on Pedicularis. Paradoxically, most emigrants reduced both their own fitness and that of the recipient populations by dispersing from a benign natal habitat to which they were maladapted into a more demanding habitat to which they were well-adapted. “Matching habitat choice” reduced fitness when evolutionary lag rendered traditional cues unreliable in a changing environment