Question

Read the following article in the link below and answer the following questions

ARTICLE (BELOW): Changes to the elevational limits and extent of species ranges associated with climate change

www.uam.es/personal_pdi/ciencias/jspinill/BIBLIOGRAFIA_CASO/ECOL_2005_8_1138_1146.pdf

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1. What is the larger ecological issue that the authors would like to address (found in the first paragraph of the introduction)?

2. What is the specific study question and/or hypothesis (or hypotheses) addressed in the paper?

3. What did the authors do? Briefly (in 2 sentences max) describe the methods or approach of the study.

4. What did the authors find? Briefly (2 sentences max) describe the most important result/finding and indicate which figure or table shows this result. This should be the answer to the specific study question or an evaluation of whether the hypothesis was supported.

Answer 1

ANSWER:

1) Climate change is expected to force species distributions towards higher elevations and latitudes, leading to extinctions of species whose future habitable climate space becomes too small or too isolated from their current geographical ranges. However, whilst many species distributions have expanded at their cool, upper elevational and latitudinal margins in conjunction with recent warming , surprisingly few range contractions have been documented at warm, lower elevational and latitudinal limits, perhaps because the locations of warm margins are determined by biotic interactions rather than climate per se , or because the mechanisms that cause extinctions are not instantaneous e.g. sporadic extreme climatic events.

2) Change in elevational associations Over 30 years of regional warming there were pronounced upward shifts in the elevational ranges of the butterflies of the Sierra de Guadarrama. For most of the 23 species of grassland butterfly studied, the optimum elevation (with the highest modelled probability of occupancy) increased from 1967–1973 to 2004, with average increases of 120–200 m, depending on the type of model used to relate occupancy to elevation, and the number of species for which the models detected an elevation with a peak probability of occupancy. Increases in optimum elevation appeared to result from extinctions at low elevations rather than colonizations at high elevations. The lowest elevation at which species were observed increased between the surveys for 17 of the 23 species. For the 16 species that were restricted to high elevations in both surveys (i.e. species at their warm range margins), the increase in lower elevational limits appeared to be independent of overall changes in occupancy: a regression of change in lower elevational limit against change in occupancy between the surveys suggested that lower elevational limits for these species had increased by 212 m .

3) Even though levels of occupancy for the study species did not change significantly between 1967–1973 and 2004, the elevational shifts in species distributions signify a substantial reduction in potentially suitable area for the 16 highelevation species. When species elevational associations were used to model regional habitat availability in the two time periods, habitable area had declined on average by 22%. The intercept of )0.34 from the regression of change in habitable area against change in occupancy implied that species that still occupied the same proportion of sample locations had suffered a reduction of 34% in habitable area, simply because of the smaller area of the landscape at progressively higher elevations.

4) The magnitude of these declines in available habitat may be typical for species that are restricted to high elevations at their warm range margins , or for endemic taxa that are entirely restricted to mountainous regions . Given the spatial isolation of suitable high elevations for these taxa, and their consequent inability to colonize new areas as the climate warms , the results forewarn of widespread extinctions unless climate change and habitat loss can be arrested.