Predicting insect phenology across space and time

Many species appear to be undergoing shifts in phenology, arising from climate change. To predict the direction and magnitude of future changes requires an understanding of how phenology depends on climatic variation. Species show large‐scale spatial variation in phenology (affected by differentiation among populations) as well as variation in phenology from year‐to‐year at the same site (affected predominantly by local plasticity). Teasing apart spatial and temporal variation in phenology should allow improved predictions of phenology under climate change. This study is the first to quantify large‐scale spatial and temporal variation in the entire emergence pattern of species, and to test the relationships found by predicting future data. We use data from up to 33 years of permanent transect records of butterflies in the United Kingdom to fit and test models for 15 butterfly species. We use generalized additive models to model spatial and temporal variation in the distribution of adult butterflies over the season, allowing us to capture changes in the timing of emergence peaks, relative sizes of peaks and/or number of peaks in a single analysis. We develop these models using data for 1973–2000, and then use them to predict phenologies from 2001 to 2006. For six of our study species, a model with only spatial variation in phenology is the best predictor of the future, implying that these species have limited plasticity. For the remaining nine species, the best predictions come from a model with both spatial and temporal variation in phenology; for four of these, growing degree‐days have similar effects over space and time, implying high levels of plasticity. The results show that statistical phenology models can be used to predict phenology shifts in a second time period, suggesting that it should be feasible to project phenologies under climate change scenarios, at least over modest time scales.     

Body size‐dependent responses of a marine fish assemblage to climate change and fishing over a century‐long scale

Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long‐term changes in species abundance and body‐size distributions. In this study, we investigated long‐term (1911–2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger‐growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller‐growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size‐dependent responses of species to long‐term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size‐selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna.     

Toward a synthetic understanding of the role of phenology in ecology and evolution

Phenology affects nearly all aspects of ecology and evolution. Virtually all biological phenomena—from individual physiology to interspecific relationships to global nutrient fluxes—have annual cycles and are influenced by the timing of abiotic events. Recent years have seen a surge of interest in this topic, as an increasing number of studies document phenological responses to climate change. Much recent research has addressed the genetic controls on phenology, modelling techniques and ecosystem-level and evolutionary consequences of phenological change. To date, however, these efforts have tended to proceed independently. Here, we bring together some of these disparate lines of inquiry to clarify vocabulary, facilitate comparisons among habitat types and promote the integration of ideas and methodologies across different disciplines and scales. We discuss the relationship between phenology and life history, the distinction between organismal- and population-level perspectives on phenology and the influence of phenology on evolutionary processes, communities and ecosystems. Future work should focus on linking ecological and physiological aspects of phenology, understanding the demographic effects of phenological change and explicitly accounting for seasonality and phenology in forecasts of ecological and evolutionary responses to climate change.     

'Back to the future': how archaeological remains can describe salmon adaptation to climate change

A strategy for species to survive climate change will be to change adaptively their way of life. Understanding rapid adaptation to climate change is therefore a priority for current research. In this issue, Turrero et al. (2012) use an original approach to unravel life history trait responses to climate change in two fish species (Salmo trutta and S. salar). Going against the flow, the authors adopt the strategy of going back to the future by investigating the responses of fish to the warming periods that followed the Last Glacial Period (approximately 30-20,000 years BP). To do this, they analysed Salmo vertebrae from well-dated archaeological sites in northern Spain in order to uncover key life history traits, which they then compared to those of contemporary specimens. They found that, as the climate got warmer, Salmo species tended to reduce the time spent in growing areas and reached spawning areas at a younger age; this tendency began approximately 15,000 years BP and accelerated in contemporary periods. The implication is a lower age at maturity and a lower reproductive success, which they tentatively related to recent declines in population growth rate. This innovative study demonstrates how changes in life history traits are linked both to the population growth rate and to the evolutionary rate under climatic constraints, which may serve as a basis for future conservation research.     

Prehistorical climate change increased diversification of a group of butterflies

Satyrinae butterflies (Lepidoptera: Nymphalidae) and grasses (Poaceae) are very diverse and distributed worldwide. Most Satyrinae use grasses as host plants, but the temporal scale of this tight association is not known. Here, we present a phylogenetic study of Satyrinae butterflies and related groups, based on 5.1 kilobases from six gene regions and 238 morphological characters for all major lineages in the 'satyrine clade'. Estimates of divergence times calibrated using a fossil from the Late Oligocene indicate that the species-rich tribe Satyrini diversified to its current 2200 species simultaneously with the expansion and radiation of grasses during the dramatic cooling and drying up of the Earth in the Oligocene. We suggest that the adaptive radiation of grass feeders in Satyrini has been facilitated by the ubiquitousness of grasses since 25Myr ago, which was triggered by a change in global climate.     

短时高温胁迫对斑痣悬茧蜂发育指标的影响

全球气候变化不仅包括平均气温上升,而且诸如热浪的极端天气事件出现的频率和程度也增大。寄生蜂虽在寄主体内完成生长发育,也会受到极端气温的影响。为探究短时高温对寄生性天敌斑痣悬茧蜂(Meteorus pulchricornis)幼虫发育表现的影响,以斜纹夜蛾(Spodoptera litura)幼虫为寄主,分别对1—6日龄子代蜂进行39℃、持续4h的高温胁迫处理,以发育全程进行适温(昼29℃、夜26℃)处理为对照,观察子代存活、发育历期、羽化和成虫寿命等发育指标。高温胁迫处理1日和5日龄子代蜂幼虫使幼虫存活率下降,与对照相比分别降低36.1%和28.6%;高温胁迫可延长子代蜂幼虫发育历期,与对照相比,高温处理2、3、5日和6日龄子代蜂幼虫使幼虫发育历期分别延长了5.0%,5.2%,7.0%和12.1%;高温胁迫处理5、6日龄子代蜂幼虫使羽化出的成虫体型(用后足胫节长度表示)比对照分别减小1.8%和2.6%。高温胁迫处理对子代蜂蛹发育历期、羽化率以及成虫寿命等均没有显著影响。研究结果说明,短时高温胁迫对斑痣悬茧蜂高龄幼虫的负面影响比对低龄幼虫大。