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Geographical Variation

Authors:
Timothy A Mousseau at University of South Carolina
Timothy A Mousseau
Alexander E Olvido
Alexander E Olvido
Alexander E Olvido
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Abstract

Geographical variation refers to differences among populations in genetically based traits across the natural geographic range of a species. Understanding the factors that give rise to and maintain geographical variation helps elucidate the causes and consequences of evolution. In the simplest case, we divide these factors into purely genetic versus environmental components to tease apart their relative contributions to observed phenotypic variation. Subsequent experiments allow us to partition further the genetic components of phenotypic variation towards a molecular understanding, hopefully to reveal the actual deoxyribonucleic acid (DNA)‐scale changes giving rise to adaptations we see at the population level. Studies of a select number of organisms – all of which begin with geographic variation – demonstrate this highly productive strategy. Given its relevance to differentiation among populations, geographic variation also has direct bearing on the question of species origins.
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... Geographical variation denotes dissimilarities between species in inherently founded characters through the habitat's natural topography. Studies on geographic variation of a number of organisms highlight clarity on causes and significance of microevolution (Olvido 2012;Wu et al. 2015). At the global level, geographic variation in phenotypic plasticity is in part due to genetic differences acquired via long-term natural selection to produce adaptation to different environments (Niskanen et al. 2017). ...
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  • Apr 2021
Saura EBD, Falcasantos GC, Andante RJM, Munda LC, Alimorong MM, Hernando BJ. 2021. Evaluation of fluctuating asymmetry and sexual dimorphism of Channa striata using landmark-based geometric morphometric analysis from Agusan Marsh and Lake Mainit in Caraga Region, Philippines. Nusantara Bioscience 13: 100-110. Evaluation was conducted to determine the impact of ecological condition to Channa striata using fluctuating asymmetry (FA) employing the landmark-based geometric morphometric analysis, using TPS software, SAGE, PAST-Hotellings Test, including Physico-chemical analysis, cyanide and four base metals. Results of Physico-chemical analysis of the two habitats showed Agusan marsh with low oxygen level (3.37-4.55) and high in Iron and TDS as compared to DENR Standards. The statistical results showed high variations (p < 0.0001) on left and right-side having percentage of 79.22% in Agusan Marsh and 72.35% in Lake Mainit which is relatively high Fluctuating Asymmetry. In terms of sex, Agusan marsh had 84.27% and 85.41% FA in males and females while Lake Mainit having 85.12% and 80.89% in males and females. The fairly similar percentage of Fluctuating Asymmetry confirms no sexual dimorphism and no shape differences between male and female, and no peculiar characters to distinguished between sexes based on the 17 landmark points. Present study concluded that FA observed in the snout tip was due to breeding behavior, the landmark points in cephalic, pectoral, and caudal region were associated with burrowing and mobility factors within the lateral line system in these fishes which thrive in high turbid habitat and low oxygen. Furthermore, it was found that the level of FA tends to increase in disturbed environs.
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... The study of geographical variation is important for elucidating the causes and consequences of evolution (Olvido and Mousseau 2012). Geographic variation among populations of the same species in phenotypic characteristics such as colouration, size and even behaviour (mating calls or displays) is common (Schäuble 2004;Bernal et al. 2005;Pröhl et al. 2007;Buckley et al. 2010;Rodríguez-Tejeda et al. 2014; Baranquet et al. 2015;Shen et al. 2015). ...
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Article
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A New Aspect of Warfarin Resistance in Wild Rats: Benefits in the Absence of Poison
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  • Jan 1993
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Two of the great mysteries of biology yet to be explored concern the distribution and abundance of genetic variation in natural populations and the genetic architecture of complex traits. These are tied together by their relationship to natural selection and evolutionary history, and some of the keys to disclosing these secrets lie in the study of wild organisms in their natural environments. This book, featuring a superb selection of papers from leading authors, summarizes the state of current understanding about the extent of genetic variation within wild populations and the ways to monitor such variation. It proposes the idea that a fundamental objective of evolutionary ecology is necessary to predict organism, population, community, and ecosystem response to environmental change. In fact, the overall theme of the papers centers around the expression of genetic variation and how it is shaped by the action of natural selection in the natural environment. Patterns of adaptation in the past and the genetic basis of traits likely to be under selection in a dynamically changing environment is discussed along with a wide variety of techniques to test for genetic variation and its consequences, ranging from classical demography to the use of molecular markers. This book is perfect for professionals and graduate students in genetics, biology, ecology, conservation biology, and evolution.
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Some genetic consequences of ice ages, and their role in divergence and speciation
Article
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