Theories Regarding The Latitudinal Diversity Gradient Biology Essay

Theories Regarding The Latitudinal Diversity Gradient Biology screenAimDifferent publications theories regarding the latitudinal transformation slope were examined and analysed to attempt to indicate how theories apologiseing the latitudinal diversity gradient oblige changed in the period 1980-2010. systemIn total, six main theories were identified from the literature and resources studied by trying abstracts and articles for relevant notice words.Main ConclusionsThe main conclusion pull was that no single speculation can adequately explain the latitudinal diversity gradient. Species diversity is ultimately controlled by a combination of operators and until on that point is conclusive proof or agreement on this subject biogeographers and biologists entrust continue to hypothesize on the matter of the driving factors behind the latitudinal diversity gradient.Key WordsLatitudinal Diversity Gradient, Geographical, Species, Species Richness, Taxa, Hypothesis,Biotic, Historic al Perturbation, humour constancy, mood Harshness, Mid- theater, evolutionary Rate, Evolution.IntroductionThe latitudinal diversity gradient is the terminal used to describe the decrease in species natality as sensation moves away from the equator. 1 Discovered by Alexander von Humboldt in 1799, it has remained i of the key questions in Evolutionary Ecology. Understanding the latitudinal diversity gradient is intrinsic in our understanding of the spread of invasive species, disease and more pertinently, the set up of global temper change (Bradford et al 2006) Hillebrand (2004) identified that this subject has real great attention but the majority of studies have concentrated on only one or a small number of organisms. An simulation of this being Krebs (1985) who examined snake and ant species throughout America. In the past 30 age there have been many different theories that attempt to explain the latitudinal diversity gradient, from further reading into each individual possibleness it became apparent that no individual theory is entirely self supporting, or else a combination of each is perhaps the scoop out way to analyze and answer the question of what is the driving factor behind the latitudinal diversity gradient.TheoriesSpecies-EnergyThe species-energy theorem centres on the hypothesis that it is the amount of available energy that governs the potential species richness of the system. Fraser and Currie examined this hypothesis in their 1995 paper The Species Richness-Energy Hypothesis in a outline Where Historical Factors are Thought to Prevail Coral Reefs. They prove that the best environmental predictors of diversity were temperature and biomass and also that there was little supporting take the stand for other hypotheses such as environmental stability. Turner et al (1987) comprise that the diversity of butterflies, measured as the number of species is highly correlated with cheerfulness and temperature during May to September, wi th these two variables accounting for nearly 80% of the variance in diversity.Mid-Domain EffectOriginally proposed by Colwell and Hurtt, (1994) this hypothesis works on the grounding that it is geographical constraints that contribute to species richness. Colwell et al (2004) state that if species ranges are shuffled randomly deep d protest a bounded geographical domain free of environmental gradients, ranges convergence increasingly toward the centre of the domain, creating a middle domain peak of species richness. on that point is still debate over whether or not the Mid Domain Effect is responsible for the latitudinal diversity gradient as data-based support for it is often weak. Zapata et al (2005) stiff Evolutionary TimeEffective evolutionary time hypothesizes that it is evolutionary time and the factors associated with it, such as environmental energy, mutation, generations and selection that are responsible for the diversity gradient. Rhode (1992) clime Harshness and Cl imate StabilityThe Climate Harshness theory speculates that fewer species are found at high latitudes due to their inability to cope with the pressures that the environment places upon them.Climate Stability proposes that the reason for the diversity gradient is due to species specializing into narrower and narrower niches due to steadfast climate conditions, resulting in change magnitude speciation and therefore resulting in temperate areas at high latitude having a low diversity as they encounter more changeable weather reddents throughout the year. Climate stability is even observed in marine environments with strong latitudinal gradients being observed. Kaustuv et al (1999) as well as in terrestrial environments. Lima-Ribeiro et al (2009).Evolutionary RateCardillo et al (2005) argue that the increased diversity observed at lower latitudes is due to high evolutionary rates resulting in increased speciation. Mettelbach et al (2007) found that there was evidence for higher rate s of variegation in the tropics, with studies of latitudinal variation suggesting greater speciation at lower latitudes. The results from these studies extract that there is indeed a link between low latitudes and evolutionary rate resulting in increased speciation.DiscussionSince the 1980s there have been suggestions of new theories and re examinations of others, for example Zapata et al (2005) re examine the mid domain effect and address its criticisms. Each of the individual theories discussed earlier proposes its own explanation for the latitudinal diversity gradient. Some hypotheses are circular and about are founded on insufficient evidence, Rhode (1992). In the past 30 years theories purporting to explain the latitudinal diversity gradient have changed from supporting one viewpoint as the sole cause of the latitudinal diversity gradient to being more inclusive of other hypotheses, the Evolutionary time theory is the most inclusive of other theories as it recognises that no single factor can be the cause of such a complex system.References and belles-lettres Cited1. On-Line Biology Book, L, Latitudinal diversity gradienthttp//mac122.icu.ac.jp/biobk/BioBookglossL.htmlAccessed on 17-08-2010Hawkins, B.A, Diniz-Filho, J.A.F, Jaramillo, C.A., Soeller, S.A., 2006. Post-Eocene climate change, niche conservatism, and the latitudinal diversity gradient of New World birds. daybook of Biogeography.Cardillo, M. Orme, C. D. L., Owens, I.P.F. 2005. Testing for Latitudinal Bias in Diversification Rates An case Using New World Birds. Ecology.Colwell, R.K. Hurtt, G.C 1994. Nonbiological Gradients in Species Richness and a inauthentic Rapoport Effect. The American naturalist, Vol. 144, No. 4 October 1994Colwell, R,K. Rahbeck,C. Gotelli, N,J. 2004 The Mid-Domain Effect and Species Richness Patters What have we in condition(p) so far? Vol. 163. No.3 March 2004Fraser, R.H, Currie, D.J. 1995. The Species Richness-Energy Hypothesis in a dodging Where Historical Factor s are Thought to Prevail Coral Reefs. The American Naturalist Vol.148, No. 1 July 1996Hillebrand, H. 2004. On the Generality of the Latitudinal Diversity Gradient. The American Naturalist, Vol 163, No. 2. 2004.Kaustuv, R., Jablonski, D., Valentine, J. W. 1999. Dissecting Latitudinal Diversity Gradients functional groups and clades of marine bivalves. The Royal troupeKrebs, C.J.1985. Ecology. The Experimental Analysis of Distribution and Abundance. Third edition. HarperRow, New York.Lima-Ribeiro, M., Diniz-Filho, J. A. F., Barberi, M. 2010. Climate Stability and the Current Patterns of Terrestrial Vertebrate Species Richness on the Brazilian Cerrado. tetrad International, Volume 222, Issue 1-2. August 2010Mittelbach, G. G., Schemske, D. W., Cornell, H. V., Allen, A. P., Brown, J. M., Bush, M. B., Harrison, S. P., Hurlbert, A. H., Knowlton, N., Lessios, H. A., McCain, C. M., McCune, A. R., McDade, L. A., McPeek, M. A., Near, T. J., Price, T. D., Ricklefs, R. E., Roy, K., Sax, D. F., Schluter, D., Sobel, J. M. and Turelli, M. 2007. Evolution and the latitudinal diversity gradient speciation, extinction and biogeography. Ecology LettersRhode, K. 1992. Latitudinal Gradients in Species Diversity The search for the primary cause. Oikos. Vol. 65, No. 3. December 1992Turner, J.R.G. Gatehouse, C.M and Corey, C.A. 1987. Does Solar Energy Control total Diversity? Butterflies, Moths and the British Climate. Oikos, Vol. 48. No.2Zapata, F.A., Gaston, K. J., Chown, S. L. 2005 The Mid-Domain Effect Revisited. The American Naturalist, Vol. 166, No. 5 November 2005.