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Buckley L.B.,University of North Carolina at Chapel Hill | Waaser S.A.,University of North Carolina at Chapel Hill | MacLean H.J.,University of North Carolina at Chapel Hill | Fox R.,Butterfly Conservation
Ecology | Year: 2011

Thermal constraints on development are often invoked to predict insect distributions. These constraints tend to be characterized in species distribution models (SDMs) by calculating development time based on a constant lower development temperature (LDT). Here, we assessed whether species-specific estimates of LDT based on laboratory experiments can improve the ability of SDMs to predict the distribution shifts of six U.K. butterflies in response to recent climate warming. We find that species-specific and constant (58C) LDT degree-day models perform similarly at predicting distributions during the period of 1970- 1982. However, when the models for the 1970-1982 period are projected to predict distributions in 1995-1999 and 2000-2004, species-specific LDT degree-day models modestly outperform constant LDT degree-day models. Our results suggest that, while including species-specific physiology in correlative models may enhance predictions of species' distribution responses to climate change, more detailed models may be needed to adequately account for interspecific physiological differences. © 2011 by the Ecological Society of America. Source

Oliver T.H.,UK Center for Ecology and Hydrology | Roy D.B.,UK Center for Ecology and Hydrology | Brereton T.,Butterfly Conservation | Thomas J.A.,University of Oxford
Global Change Biology | Year: 2012

Populations at the high latitude edge of species' geographical ranges are thought to show larger interannual population fluctuations, with subsequent higher local extinction risk, than those within the 'core' climatic range. As climate envelopes shift northward under climate warming, however, we would expect populations to show dampened variability. We test this hypothesis using annual abundance indices from 19 butterfly species across 79 British monitoring sites between 1976 and 2009, a period of climatic warming. We found that populations in the latter (warmer) half of the recording period show reduced interannual population variability. Species with more southerly European distributions showed the greatest dampening in population variability over time. Our results suggest that increases in population variability occur towards climatic range boundaries. British sites, previously existing at the margins of suitable climate space, now appear to fall closer to the core climatic range for many butterfly species. © 2012 Blackwell Publishing Ltd. Source

Fox R.,Butterfly Conservation
Insect Conservation and Diversity | Year: 2013

1.Population declines among insects are inadequately quantified, yet of vital importance to national and global biodiversity assessments and have significant implications for ecosystem services. 2.Substantial declines in abundance and distribution have been reported recently within a species-rich insect taxon, macro-moths, in Great Britain and other European countries. These declines are of concern because moths are important primary consumers and prey items for a wide range of other taxa, as well as contributing to ecosystem services such as pollination. 3.I summarise these declines and review potential drivers of change. Direct evidence for causes of moth declines is extremely limited, but correlative studies and extrapolation from closely related taxa suggest that habitat degradation (particularly because of agricultural intensification and changing silviculture) and climate change are likely to be major drivers. There is currently little evidence of negative population-level effects on moths caused by chemical or light pollution, non-native species or direct exploitation. 4.I make suggestions for future research with a focus on quantifying impacts of land management practices, light pollution and climate change on moth population dynamics and developing evidence-based measures that can be incorporated into agri-environment schemes and other policy initiatives to help reverse the widespread decline of moths in Great Britain and beyond. © 2012 The Author. Insect Conservation and Diversity © 2012 The Royal Entomological Society. Source

Oliver T.H.,UK Center for Ecology and Hydrology | Brereton T.,Butterfly Conservation | Roy D.B.,UK Center for Ecology and Hydrology
Ecography | Year: 2013

Most studies on the biological impact of climate change have focussed on incremental climate warming, rather than extreme events. Yet responses of species' populations to climatic extremes may be one of the primary drivers of ecological change. We assess the resilience of individual populations in terms of their sensitivity to- and ability to recover from- environmental perturbation. We demonstrate the method using a model species, the ringlet butterfly Aphantopus hyperantus, and analyse the effects of an extreme drought event using data from 79 British sites over 10 yr. We find that populations crashed most severely in drier regions but, additionally, the landscape structure around sites influenced population responses. Larger and more connected patches of woodland habitat reduced population sensitivity to the drought event and also facilitated faster recovery. Having enough, sufficiently connected habitat appears essential for species' populations to be resilient to the increased climatic variability predicted under future scenarios. © 2012 The Authors. Ecography © 2012 Nordic Society Oikos. Source

Hodgson J.A.,University of York | Thomas C.D.,University of York | Oliver T.H.,UK Center for Ecology and Hydrology | Anderson B.J.,University of York | And 2 more authors.
Global Change Biology | Year: 2011

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. © 2010 Blackwell Publishing Ltd. Source

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