Amy E. Hinks

Cognitive Ability Influences Reproductive Life History Variation in the Wild

Cognition has been studied intensively for several decades, but the evolutionary processes that shape individual variation in cognitive traits remain elusive [1-3]. For instance, the strength of selection on a cognitive trait has never been estimated in a natural population, and the possibility that positive links with life history variation [1-5] are mitigated by costs [6] or confounded by ecological factors remains unexplored in the wild. We assessed novel problem-solving performance in 468 wild great tits Parus major temporarily taken into captivity and subsequently followed up their reproductive performance in the wild. Problem-solver females produced larger clutches than nonsolvers. This benefit did not arise because solvers timed their breeding better, occupied better habitats, or compromised offspring quality or their own survival. Instead, foraging range size and day length were relatively small and short, respectively, for solvers, suggesting that they were more efficient at exploiting their environment. In contrast to the positive effect on clutch size, problem solvers deserted their nests more often, leading to little or no overall selection on problem-solving performance. Our results are consistent with the idea that variation in cognitive ability is shaped by contrasting effects on different life history traits directly linked to fitness [1, 3].

Mhc supertypes confer both qualitative and quantitative resistance to avian malaria infections in a wild bird population.

Major histocompatibility complex (Mhc) genes are believed to play a key role in the genetic basis of disease control. Although numerous studies have sought links between Mhc and disease prevalence, many have ignored the ecological and epidemiological aspects of the host–parasite interaction. Consequently, interpreting associations between prevalence and Mhc has been difficult, whereas discriminating alleles for qualitative resistance, quantitative resistance and susceptibility remains challenging. Moreover, most studies to date have quantified associations between genotypes and disease status, overlooking the complex relationship between genotype and the properties of the Mhc molecule that interacts with parasites. Here, we address these problems and demonstrate avian malaria (Plasmodium) parasite species-specific associations with functional properties of Mhc molecules (Mhc supertypes) in a wild great tit (Parus major) population. We further show that correctly interpreting these associations depends crucially on understanding the spatial variation in risk of infection and the fitness effects of infection. We report that a single Mhc supertype confers qualitative resistance to Plasmodium relictum, whereas a different Mhc supertype confers quantitative resistance to Plasmodium circumflexum infections. Furthermore, we demonstrate common functional properties of Plasmodium-resistance alleles in passerine birds, suggesting this is a model system for parasite–Mhc associations in the wild.

A Problem Shared Is a Problem Reduced: Seeking Efficiency in the Conservation of Felids and Primates

Threats faced by mammalian species can be grouped into one of a handful of categories, such as habitat loss, unsustainable hunting and persecution. Insofar as they face common threats, diverse species may benefit from the same conservation intervention, thereby offering efficiencies in conservation action. We explore this proposition for primates and felids by examining coarse scale overlaps in geographical distributions, using IUCN Red List assessments of the primary threats posed to each species. A global analysis of primates and felids that face common threats reveals the greatest overlap is in Central and South Asia, where up to 14 primates and felids co-occur. More than 80% of the land where at least 1 threatened species of either primate or felid occurs also contains at least one threatened species of the other taxon, yet over 60% of these grid cells containing both threatened primates and felids lie outside Conservation International’s hot spots. A review of IUCN Action Plans of the threats to felids and primates strongly supports the hypothesis that they are often the same and occur in the same place. In principle, steps to conserve big cats have the potential to benefit several species of threatened primates, and vice versa.

Scale-dependent phenological synchrony between songbirds and their caterpillar food source.

In seasonal environments, the timing of reproduction has important fitness consequences. Our current understanding of the determinants of reproductive phenology in natural systems is limited because studies often ignore the spatial scale on which animals interact with their environment. When animals use a restricted amount of space and the phenology of resources is spatially variable, selection may favor sensitivity to small-scale environmental variation. Population-level studies of how songbirds track the changing phenology of their food source have been influential in explaining how populations adjust to changing climates but have largely ignored the spatial scale at which phenology varies. We explored whether individual great tits (Parus major) synchronize their breeding with phenological events in their local environment and investigated the spatial scale at which this occurs. We demonstrate marked variation in the timing of food availability, at a spatial scale relevant to individual birds, and that such local variation predicts the breeding phenology of individuals. Using a 45-year data set, we show that measures of vegetation phenology at very local scales are the most important predictors of timing of breeding within years, suggesting that birds can fine-tune their phenology to that of other trophic levels. Knowledge of the determinants of variation in reproductive behavior at different spatial scales is likely to be critical in understanding how selection operates on breeding phenology in natural populations.

Life and Dinner under the Shared Umbrella: Patterns in Felid and Primate Communities

Sympatry between primates and felids is potentially relevant to both their behavioural ecology and their conservation. This paper briefly introduces felids and primates, for the purposes of assessing their interrelationships and the patterns in their spatial congruence using IUCN spatial data. First, we review evidence and opportunity for predator-prey interactions between the felids and primates. Second, we analyse the overlap between species of the two taxa to reveal the potential of particular felid species or guilds (unique combinations of 2 or more felids) to act as umbrellas for the conservation of co-occurring primates. Felid guilds vary in terms of their geographical ranges and numbers of members. Some felid species overlap the ranges of many primate species, and the most speciose felid guilds, while geographically limited in distribution, have the potential to act as protective umbrellas to large numbers of primate species. This prompts the hypothesis that threatened primates and felids are facing similar threats and might thus benefit from similar interventions, which is evaluated in a sister paper by Macdonald et al. in this special issue.

Learning from the past to prepare for the future: felids face continued threat from declining prey

Many contemporary species of large-felids (>15 kg) feed upon prey that are endangered, raising concern that prey population declines (defaunation) will further threaten felids. We assess the threat that defaunation presents by investigating a late Quaternary (LQ), ‘present-natural’ counterfactual scenario. Our present-natural counterfactual is based on predicted ranges of mammals today in the absence of any impacts of modern humans (Homo sapiens) through time. Data from our present-natural counterfactual are used to understand firstly how megafauna extinction has impacted felid communities to date and secondly to quantify the threat to large-felid communities posed by further declines in prey richness in the future. Our purpose is to identify imminent risks to biodiversity conservation and their cascading consequences and, specifically, to indicate the importance of preserving prey diversity. We pursue two lines of enquiry; first, we test whether the loss of prey species richness is a potential cause of large-felid extinction and range loss. Second, we explore what can be learnt from the large-scale large-mammal LQ losses, particularly in the Americas and Europe, to assess the threat any further decline in prey species presents to large-felids today, particularly in Africa and Asia. Large-felid species richness was considerably greater under our present-natural counterfactual scenario compared to the current reality. In total, 86% of cells recorded at least one additional felid in our present-natural counterfactual, and up to 4-5 more large-felids in 10% of the cells. A significant positive correlation was recorded between the number of prey species lost and the number of large-felids lost from a cell. Extant felids most at risk include lion and Sunda clouded leopard, as well as leopard and cheetah in parts of their range. Our results draw attention to the continuation of a trend of megafauna decline that began with the emergence of hominins in the Pleistocene.