Climate causes shifts in grey seal phenology by modifying age structure.

There are numerous examples of phenological shifts that are recognized both as indicators of climate change and drivers of ecosystem change. A pressing challenge is to understand the causal mechanisms by which climate affects phenology. We combined annual population census data and individual longitudinal data (1992-2018) on grey seals, Halicheorus grypus, to quantify the relationship between pupping season phenology and sea surface temperature. A temperature increase of 2°C was associated with a pupping season advance of approximately seven days at the population level. However, we found that maternal age, rather than sea temperature, accounted for changes in pupping date by individuals. Warmer years were associated with an older average age of mothers, allowing us to explain phenological observations in terms of a changing population age structure. Finally, we developed a matrix population model to test whether our observations were consistent with changes to the stable age distribution. This could not fully account for observed phenological shift, strongly suggesting transient modification of population age structure, for example owing to immigration. We demonstrate a novel mechanism for phenological shifts under climate change in long-lived, age- or stage-structured species with broad implications for dynamics and resilience, as well as population management.

Census data aggregation decisions can affect population-level inference in heterogeneous populations.

Conservation and population management decisions often rely on population models parameterized using census data. However, the sampling regime, precision, sample size, and methods used to collect census data are usually heterogeneous in time and space. Decisions about how to derive population-wide estimates from this patchwork of data are complicated and may bias estimated population dynamics, with important implications for subsequent management decisions.Here, we explore the impact of site selection and data aggregation decisions on pup survival estimates, and downstream estimates derived from parameterized matrix population models (MPMs), using a long-term dataset on grey seal (Halichoerus grypus) pup survival from southwestern Wales. The spatiotemporal and methodological heterogeneity of the data are fairly typical for ecological census data and it is, therefore, a good model to address this topic.Data were collected from 46 sampling locations (sites) over 25 years, and we explore the impact of data handling decisions by varying how years and sampling locations are combined to parameterize pup survival in population-level MPMs. We focus on pup survival because abundant high-quality data are available on this developmental stage.We found that survival probability was highly variable with most variation being at the site level, and poorly correlated among sampling sites. This variation could generate marked differences in predicted population dynamics depending on sampling strategy. The sample size required for a confident survival estimate also varied markedly geographically.We conclude that for populations with highly variable vital rates among sub-populations, site selection and data aggregation methods are important. In particular, including peripheral or less frequently used areas can introduce substantial variation into population estimates. This is likely to be context-dependent, but these choices, including the use of appropriate weights when summarizing across sampling areas, should be explored to ensure that management actions are successful.

Descriptive survey of non-commercial randomised controlled trials in the United Kingdom, 1980-2002.

OBJECTIVES: To describe the characteristics of randomised controlled trials supported by the main non-commercial sources of funding in the United Kingdom between 1980 and 2002. DESIGN: Descriptive survey. SETTING: Randomised controlled trials funded by the Medical Research Council, NHS research and development programme, Department of Health, Chief Scientist Office in Scotland, and medical research charities. PARTICIPANTS: 1464 randomised controlled trials supported by the main non-commercial sources of funding. RESULTS: Support for randomised controlled trials by the main sources of non-commercial funding in the United Kingdom has fallen in recent years, without any concomitant increase in the sample sizes of these studies. Drug trials in a limited range of health problems have dominated among the studies supported by the Medical Research Council and medical research charities. Until recently, the NHS research and development programme supported randomised controlled trials of various healthcare interventions, in a wide range of health problems, but between 1999 and 2002 many of the subprogrammes that had commissioned trials were discontinued. CONCLUSIONS: The future of non-commercial randomised controlled trials in the United Kingdom has been threatened by the discontinuation or demise of national and regional NHS research and development programmes. Support also seems to be declining from the Medical Research Council and the medical research charities. It is unclear what the future holds for randomised controlled trials that address issues of no interest to industry but are of great importance to patients and practitioners.