Climate Change and the Population Extinction - Essay Example

Literature review The purpose of this study was to evaluate the impact of climate change on the population extinction of two species of checkerspot butterfly. This study evolved from the fact that population abundance, population migration; geographic range shifts and precipitation variability are the definite consequences of climate change. The study has evaluated two different sources against the population simulations in two different times. The results clearly indicated that the precipitation variability hindered the overlap of larvae and plants, increasing larval mortality. The study concluded that climate change accelerated the extinction of the butterfly species. Topic of the study: Climate change hastens population extinctions. Literature review: The climate system is a complex, interactive system consisting of the atmosphere, land surface, snow and ice, oceans and other bodies of water, and living things. Climate is usually described in terms of the mean and variability of temperature, precipitation and wind over a period, ranging from months to millions of years (the classical period is 30 years). Global warming the most visible aspect of climate change affects our whole climate system including humans worldwide. In the past three decades the EL Nino effect in the Southern hemisphere has become more intense, causing greater variation in rainfall. . North America and Central Asia will warm more than the oceans or coastal regions. Precipitation will increase overall, but there will be sharp regional variations, with some areas that now receive adequate rainfall becoming arid. The consequences for non-human animals and bio-diversity will also be severe. In some regions plant and animal communities will gradually move further from the equator, or to higher altitudes, following climate patterns. Australia's unique alpine plants and animals already survive only on the country's highest alpine plains and peaks. If snow ceases to fall on their territory, they will become extinct. Similarly, many species are also shifting towards favorable climatic zones or facing threats of extinction. One such species is Checkerspot butterfly. Recent studies are pointing out that climate change may be one of the factors for extinction of species but not the sole reason. Therefore, the detection and attribution of climate change in natural system has been a challenge for climate change biologists. Assigning climate change as the cause of the observed biotic changes has often had a deeper basis, such as a known mechanistic link between climate variables and biology of the study of species (Parmesan et al. 2000). On a continental scale, movements of the entire species ranges have been found in butterflies in both north America and Europe, where two thirds of the 58 species studied have shifted their ranges northward (Parmesan, 1996; Parmesan et al. 1999). Seventy years of published studies document the limiting effects of temperature on butterfly population dynamics, particularly at northern range edges (Parmesan, 2003). The northern boundaries of many European butterflies are correlated with summertime isotherms (Thomas, 1993). Montane studies are lesser in numbers and less documented but these shows upward movement of species in general. In one of the studies, Parmesan (1996) found that Edith's Checkerspot butterfly has shifted upwards by 105m in the Sieara Nevada Mountains of California. Now apart from warming impacts, the difference in rainfall has some impact on movement/extinction of species/plants. In one of the study, at sites in Alaska, more recent decades have been relatively dry, which is believed to have prevented trees from responding to current warming as they did before (Barber et al., 2000) Precipitation changes may also be the reason for shifting/extinction. Recent trends toward increased precipitation have seen to be driving vegetation compositions to be altering the relative abundances of species within Rodent, reptile and ant communities (Brown et al. 1997). Theory indicates that a highly dispersive species would be better able to exploit small isolated patches of habitat (Thomas, 2000). In a study, looking at the average movement over all butterflies, the mean change in geographic location of the range is of same order as the regional mean change in temperature isolated about 100 km for both over 100 years (Permesan,1996; Parmesan et al.,1999). Similarly, In Northern Europe, some species that specialize in hot microclimates may actually be experiencing cooling trends due to changes in human land management (Thomas 1993). For example; Lysandra bellargus (Lycaenid butterfly) requires extremely short turf where the soil and host plants are especially warm. In northern Europe, this requirement has long restricted the insects to chalk downs. However, vegetation height has recently increased in these habitats as sheep and rabbit grazing has declined, resulting in local microclimate cooling and thereby necessitating active management of the few remaining butterfly population. Similarly, the Nymphalid butterfly requires open woodlands so that sun may penetrate to the forest floor where its larvae feed on violets. Closing of the forest canopy due to changes in woodland management has shaded the host plants and cooled the microclimate in Great Britain (Thomas, 1993). A Paphia is only showing signs of northward expansion, a response lag to the warming trends of more than 20 years (Thomas, 2000). Recent northern ranges expansion however has coincided with colonization of non-southern slopes (Thomas et al. 2001). Parmesan et al. (1999) in their study of 57 species of European butterflies collected data from both the northern and southern range boundaries of 35 species (Parmesan et al., 1999). Trends at the Northern Boundary were mimicked at the southern boundary for only half (17 Species) causing possible problems of interpretation. However, it has been found that most of the species and discrepancies between edges consisted of one boundary being stable while the other shifted as expected from warming trends. Even in a study conducted in Finland found that the type of roads (habitats) plays an important factors regarding species richness. Butterfly diversity increased on verge of narrow roads of wider high ways. Results indicate that road verges should be considered an important reserve for species dependent on semi-natural grassland in Finland (Saarinen et al. 2005). In another study in Czech Republic, a study found that altitude shift in distribution of Czech butterflies is already detectable on the coarse scale of standard distribution map (Konvicka et al., 2005). In one of the famous and long time study Rosa Manendez et al. (2006) find that it may be decades or centuries before the species richness and composition of biological communities adjusts to the current climate. The study, investigated that whether changes in species richness using the well-monitored British butterfly fauna can be taken as a model system. During the study, it has been observed that average species richness of resident butterfly species has increased in recent decades. These changes are as great as would be expected given the amount of warming that has taken place (Roy & Sparus, 2000). The composition of butterflies' communities is changing towards dominance by generalist species (Warren et al. 2001). Finally, study concluded that species are lagging behind climate and that generalist butterflies are primarily limited by climate whereas specialists are also limited by other factors. Most individuals of specialist species would fail to find suitable habitats, either retarding the rate of range expansion or halting it entirely. Biodiversity researchers frequently adopt the term extinction debt to devote the time delay between environmental change and the extinctions that eventually take place as result of those environmental changes (Tilman et al., 1994). Many empirical studies have been carried out understand the complex relationship between climate changes and survivals of Edith Checkerspot butterfly. The relationship cannot be attributed to be direct effects to temperature or precipitation but indirect effects due to timing of butterfly life cycles relative to that of their host and nectar plants. At low to moderate elevation sites it is routine that majority of larvae starve because they are not large enough to enter their summer resting stage (diapauses) when their annual host plants senesce in late spring time (Singer 1971,72). The degree of mortality at this level depends on the phase relationship is strongly affected by temperature and precipitation, both year to year variation and systematic trends in climate will effects this synchrony (Boughton 1999). Hotter temperature results in shortening of larval duration by several days over a 10-14 day period (Boughton, 1999). The ultimate population response to systematic climatic trends depends on the interplay between 1) host - plant distribution across the micro and micro-topographic landscape 2) Larval & adult dispersal & 3) Female choice of oviposition sites (Parmesan, 2005). Direct observation of population extinctions over the years indicate that many of them were caused by extreme climate years and unusual whether events (Mclaughlin et al., 2002). In the case study conducted by Parmesan (2005) it has been concluded that a general link between these apparently disparate population extinctions and human mediated climate change can be sought by scaling up from that population level and looking for patterns across multiple extinctions events and over a large geographical area across which regional climate change has been documented. Modern censuses of the historical sites several an asymmetrical patterns of the population extinctions on a continental scale (Parmesan, 1996). While climate change could caused suitable responses, or responses idiosyncratic fro each habitat type actual patterns of extinction in checkerspot butterfly was quite simple; population extinctions were four times as high along the southern range boundary than among the northern range boundary and nearly three times as high at lower elevation than higher elevations (Parmesan, 1996). Habitat suitability has been assessed by parmesan. It has been assessed based on previously determined criteria of host and nectar plant quality and density analysis has shown that other anthropogenic factors (such as proximity to large urban areas) were not associated with observed extinctions pattern. Regional climate warming is, by default, the most likely cause of the observed distributional shift. The trends towards heavier snow pack at the highest, elevation delays flight season until season until the most climatically suitable (warm & sunny) months of July & August, assisting rapid, in impeded growth of off spring up to diapauses. In the southern most population, a gradual warming or drying trends (Karl et al. 1996) has likely to lead to a steady shortening of the window of time in which the host is edible, causing increased larval morality and hence increased population extinction. Conclusion: Thus systematic climate trends are highly plausible drivers of northward and upward range shift of Checkerspot butterfly. In short term, these butterflies, which have the high extinctions rate of southern population implies a light adaptation to local conditions, with little adaptation to local conditions with little evidence for flexibility in its behavior or life history strategies (Singer, 1994). However, Checkersopt butterflies have also demonstrated a remarkable ability for rapid evolution under novel conditions (Singer et al. 1993) which makes long-term response to climate change more difficult to predict. Finally, we can say that climate change may have some impact on butterflies but human population growth patterns, changes in communities' compositions, land use practices are other reasons to look at for population shift/extinction. References: 1. Barber V. A., G. P. Juday and B. P. Finney 2000. Reduced growth of Alaskan white spruce in the twentieth century from temperature induced drought stress, nature, 405: 668-673. 2. Boughton, D. A., 1999, Empirical evidence for source sink dynamics in a butterfly: Temporal barriers and alternative states. Ecology 80:2727-2739. 3. Brown J. H., T. T. Valone and C. G. Curtin, 1997 Reorganization of an arid ecosystem in response to recent climate change, Proceeding national academy science USA 94: 9729-9733. 4. Karl, T. R., R. W. Knight, D. R. Easterling and R. G. Quayle, 1996 Indices of climate change for the United States, Bulletin American meteorological society 77: 279-292. 5. Konvicka, Martin Monika Maradova, Jiri Benes, Zdenek Fric and Pavel Kepka 2005, Uphill shifts in distribution of butterflies in the Czech Republic: effects of changing climate etected on a regional scale, Global ecology and Biogeography, Volume 12 Issue 5,'Pages'403'-'410 (http://www3.interscience.wiley.com/journal/118854125/abstract). 6. McLaughlin, J. F., J. J. Hellmann, C. L. Boggs and P. R. Ehrlich, 2002, Climate change hastens population extinctions. Proceeding National Academy Science USA 99(9): 6070-6074. 7. Mene'ndez, R., Gonza'lez-Meg''as, A., Collingham, Y., Fox, R., Roy, D. B. & Thomas, C. D., 2006 Species richness changes lag behind climate change, Proc. R. Soc. B, 273, 1465-1470 http://journals.royalsociety.org/content/e0x3g307758q9w08/fulltext.pdf. 8. Parmesan C. 2005 Detection of multiple levels euphydryas editha and climate change in Climate Change and Biodiversity edited by Thomas E. Lovejoy and Lee Hannah, Yale university press, pp. 56-60 (http://books.google.com/books'id=efP4ZWQXgdMC&pg=PA56&lpg=PA56&dq=climate+change+and+butterfly&source=web&ots=LcxaWBV9S6&sig=X_VAHHyBpzHqlQqObE5r5fpebZs&hl=en&sa=X&oi=book_result&resnum=10&ct=result#PPA42,M1). 9. Parmesan, C. & Yohe, G. 2003 A globally coherent fingerprint of climate change impacts across natural systems. Nature 421, 37-42. (http://www.nature.com/nature/journal/v421/n6918/abs/nature01286.html,doi:10.1038/nature01286). 10. Parmesan, C. 1996, Climate and species range, Nature 382: 765-766. 11. Parmesan, C. 2003, Butterflies as bio-indicators of climate change impacts. In evolution and ecology taking flight: butterflies and model systems, C. L. Blogs, W. B. Watt and P. R. Ehrlich, eds. Chicago, University of Chicago Press. 12. Parmesan, C. et al. 1999 Poleward shifts in geographical ranges of butterfly species associated with regional warming. Nature 399, 579-583. (doi:10.1038/21181). 13. Parmesan, C., T. L. Root, M. Willing, 2000, Impacts of extreme weather and climate on terrestrial biota, Bulletin American Meteorological Society, 81:443-450. 14. Roy, D. B. & Sparks, T. H. 2000 Phenology of British butterflies and climate change. Global Change Biol. 6, 407-416. (doi:10.1046/j.1365-2486.2000.00322.x). 15. Saarinen, Kimmo, Anu Valtonen, Juha Jantunen, and Sanna Saarnio, 2005, Butterflies and diurnal moths along road verges: Does road type affect diversity and abundance' Biological conservation, volume 123, issue 3, June 2005, Pages 403-412 (doi:10.1016/j.biocon.2004.12.012''''http://www.sciencedirect.com/science'_ob=ArticleURL&_udi=B6V5X-4F97G5C-1&_user=10&_coverDate=06%2F01%2F2005&_rdoc=15&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235798%232005%23998769996%23563277%23FLA%23display%23Volume)&_cdi=5798&_sort=d&_docanchor=&view=c&_ct=15&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=5513e042acbc81e01f95b87bdb395e4d). 16. Singer M. C. 1971 Population dynamics and host relations of the butterfly eupbydryas editha Ph.d. Dissertation, Stanford University. 17. Singer M. C. 1972 Determinants of multiple hosts use by a phytophagous insect population. Evolution 37: 389-403. 18. Singer M. C. 1994 Behavioral constraints on the evolutionary expansion of insect diet: a case history from Chekerspot butterflies, In behavioral mechanisms in evolutionary ecology L. Realed. Pp. 279-296. Chicago: University of Chicago press. 19. Singer, M. C., C. D. Thomas and C. Parmesan 1993, Rapid human-induced evolution of insect host associations, Nature 366:681-683. 20. Thomas C.D. 2000 Dispersal and extinction in fragmented landscapes proc. Royal society of London, B. 267:139-145. 21. Thomas, C. D., Bodsworth, E. J., Wilson, R. J., Simmons, A. D., Davies, Z. G., Musche, M. & Conradt, L. 2001 Ecological and evolutionary processes at expanding range margins. Nature 411, 577-581. (doi:10.1038/35079066). 22. Thomas, J. A. 1993, Holocene climate changes and warm man-made refugia may explain why a sixth butterfly possess early succession habitats, Ecology 16:278-284. 23. Tilman, D., May, R. M., Lehman, C. L. & Nowak, M. A. 1994 Habitat destruction and the extinction debt. Nature 371, 65-66. (doi:10.1038/371065a0). 24. Warren, M. S. et al. 2001 Rapid responses of British butterflies to opposing forces of climate and habitat change. Nature 414, 65-69. (doi:10.1038/35102054). Read More