Papers by David Gutierrez
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Oecologia, 1999
Two general approaches have usually been taken towards understanding the distributions and dynami... more Two general approaches have usually been taken towards understanding the distributions and dynamics of localised species in heterogeneous landscapes, namely habitat characterisation and metapopulation dynamics. We show how habitat and metapopulation dynamics interact to generate a highly localised distribution of a butterfly, despite the extremely widespread nature of the butterfly’s host plant. Egg placement, macro-habitat requirements and dispersal were studied for the butterfly Erynnis tages, in North Wales, where it shows a restricted distribution relative to that of its host plant, Lotus corniculatus. Females laid eggs disproportionately on large plants growing in hollows, with intermediate cover of bare ground and high cover of L. corniculatus. Ideal macro-habitat, studied at 100-m grid resolution, consisted of areas with high host plant densities, sheltered from wind, with light or no grazing or cutting. These specialised conditions are represented as localised patches in the landscape, and define the potential habitat network, within which metapopulation dynamics take place. Although there was a moderate (22%) level of exchange of individual E. tages among local populations, the total number of potential colonists in the whole system was low because source population sizes were small (≤200 individuals at peak in any site in 1997 and 1998). Four unoccupied but apparently suitable 500-m grid squares were colonised between 1997 and 1998, and isolated habitat was less likely to be occupied. Overall, our study suggests that long-term regional persistence of E. tages is very likely to depend on metapopulation processes within the restricted patch network, rather than on the long-term survival of local populations.
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Journal of Biogeography, 1997
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Journal of Applied Ecology, 2000
1. Most species’ surveys and biodiversity inventories are limited by time and money. Therefore, i... more 1. Most species’ surveys and biodiversity inventories are limited by time and money. Therefore, it would be extremely useful to develop predictive models of animal distributions based on habitat, and to use these models to estimate species' densities and range sizes in poorly sampled regions.2. In this study, two sets of data were collected. The first set consisted of over 2000 butterfly transect counts, which were used to determine the relative density of each species in 16 major habitat types in a 35-km2 area of fragmented landscape in north-west Wales. For the second set of data, the area was divided into 140 cells using a 500-m grid, and the extent of each habitat and the presence or absence of each butterfly and moth species was determined for each cell.3. Logistic regression was used to model the relationship between species’ distribution and predicted density, based on habitat extent, in each grid square. The resultant models were used to predict butterfly distributions and occupancy at a range of spatial scales.4. Using a jack-knife procedure, our models successfully reclassified the presence or absence of species in a high percentage of grid squares (mean 83% agreement). There were highly significant relationships between the modelled probability of species occurring at regional and local scales and the number of grid squares occupied at those scales.5. We conclude that basic habitat data can be used to predict insect distributions and relative densities reasonably well within a fragmented landscape. It remains to be seen how accurate these predictions will be over a wider area.
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Ecological Entomology, 2002
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Journal of Animal Ecology, 2008
1The ranges of many species have expanded in cool regions but contracted at warm margins in respo... more 1The ranges of many species have expanded in cool regions but contracted at warm margins in response to recent climate warming, but the mechanisms behind such changes remain unclear. Particular debate concerns the roles of direct climatic limitation vs. the effects of interacting species in explaining the location of low latitude or low elevation range margins.2The mountains of the Sierra de Guadarrama (central Spain) include both cool and warm range margins for the black-veined white butterfly, Aporia crataegi, which has disappeared from low elevations since the 1970s without colonizing the highest elevations.3We found that the current upper elevation limit to A. crataegi's distribution coincided closely with that of its host plants, but that the species was absent from elevations below 900 m, even where host plants were present. The density of A. crataegi per host plant increased with elevation, but overall abundance of the species declined at high elevations where host plants were rare.4The flight period of A. crataegi was later at higher elevations, meaning that butterflies in higher populations flew at hotter times of year; nevertheless, daytime temperatures for the month of peak flight decreased by 6·2 °C per 1 km increase in elevation.5At higher elevations A. crataegi eggs were laid on the south side of host plants (expected to correspond to hotter microclimates), whereas at lower sites the (cooler) north side of plants was selected. Field transplant experiments showed that egg survival increased with elevation.6Climatic limitation is the most likely explanation for the low elevation range margin of A. crataegi, whereas the absence of host plants from high elevations sets the upper limit. This contrasts with the frequent assumption that biotic interactions typically determine warm range margins, and thermal limitation cool margins.7Studies that have modelled distribution changes in response to climate change may have underestimated declines for many specialist species, because range contractions will be exacerbated by mismatch between the future distribution of suitable climate space and the availability of resources such as host plants.The ranges of many species have expanded in cool regions but contracted at warm margins in response to recent climate warming, but the mechanisms behind such changes remain unclear. Particular debate concerns the roles of direct climatic limitation vs. the effects of interacting species in explaining the location of low latitude or low elevation range margins.The mountains of the Sierra de Guadarrama (central Spain) include both cool and warm range margins for the black-veined white butterfly, Aporia crataegi, which has disappeared from low elevations since the 1970s without colonizing the highest elevations.We found that the current upper elevation limit to A. crataegi's distribution coincided closely with that of its host plants, but that the species was absent from elevations below 900 m, even where host plants were present. The density of A. crataegi per host plant increased with elevation, but overall abundance of the species declined at high elevations where host plants were rare.The flight period of A. crataegi was later at higher elevations, meaning that butterflies in higher populations flew at hotter times of year; nevertheless, daytime temperatures for the month of peak flight decreased by 6·2 °C per 1 km increase in elevation.At higher elevations A. crataegi eggs were laid on the south side of host plants (expected to correspond to hotter microclimates), whereas at lower sites the (cooler) north side of plants was selected. Field transplant experiments showed that egg survival increased with elevation.Climatic limitation is the most likely explanation for the low elevation range margin of A. crataegi, whereas the absence of host plants from high elevations sets the upper limit. This contrasts with the frequent assumption that biotic interactions typically determine warm range margins, and thermal limitation cool margins.Studies that have modelled distribution changes in response to climate change may have underestimated declines for many specialist species, because range contractions will be exacerbated by mismatch between the future distribution of suitable climate space and the availability of resources such as host plants.
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Journal of Animal Ecology, 2001
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Journal of Animal Ecology, 2001
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Ecology, 2001
... Gutiérrez, David, Jorge L. León-Cortés, Rosa Menéndez, Robert J. Wilson, Matthew JR Cowley, a... more ... Gutiérrez, David, Jorge L. León-Cortés, Rosa Menéndez, Robert J. Wilson, Matthew JR Cowley, and Chris D. Thomas. 2001. ... David Gutiérrez 1 , Jorge L. León-Cortés 2 , Rosa Menéndez 1 , Robert J. Wilson, Matthew JR Cowley, and Chris D. Thomas ...
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Ecology Letters, 2005
The first expected symptoms of a climate change-generated biodiversity crisis are range contracti... more The first expected symptoms of a climate change-generated biodiversity crisis are range contractions and extinctions at lower elevational and latitudinal limits to species distributions. However, whilst range expansions at high elevations and latitudes have been widely documented, there has been surprisingly little evidence for contractions at warm margins. We show that lower elevational limits for 16 butterfly species in central Spain have risen on average by 212 m (± SE 60) in 30 years, accompanying a 1.3 °C rise (equivalent to c. 225 m) in mean annual temperature. These elevational shifts signify an average reduction in habitable area by one-third, with losses of 50–80% projected for the coming century, given maintenance of the species thermal associations. The results suggest that many species have already suffered climate-mediated habitat losses that may threaten their long-term chances of survival.
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Global Change Biology, 2007
The geographic ranges of many species have shifted polewards and uphill in elevation associated w... more The geographic ranges of many species have shifted polewards and uphill in elevation associated with climate warming, leading to increases in species richness at high latitudes and elevations. However, few studies have addressed community-level responses to climate change across the entire elevational gradients of mountain ranges, or at warm lower latitudes where ecological diversity is expected to decline. Here, we show uphill shifts in butterfly species richness and composition in the Sierra de Guadarrama (central Spain) between 1967–1973 and 2004–2005. Butterfly communities with comparable species compositions shifted uphill by 293 m (± SE 26), consistent with an upward shift of approximately 225 m in mean annual isotherms. Species richness had a humped relationship with elevation, but declined between surveys, particularly at low elevations. Changes to species richness and composition primarily reflect the loss from lower elevations of species whose regional distributions are restricted to the mountains. The few colonizations by specialist low-elevation species failed to compensate for the loss of high-elevation species, because there are few low-elevation species in the region and the habitat requirements of some of these prevent them from colonizing the mountain range. As a result, we estimated a net decline in species richness in approximately 90% of the region, and increasing community domination by widespread species. The results suggest that climate warming, combined with habitat loss and other drivers of biological change, could lead to significant losses in ecological diversity in mountains and other regions where species encounter their lower latitudinal-range margins.
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BMC Medical Education, 2006
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Papers by David Gutierrez