Reproduced from Kaufman, D.M., 1995. latitudinal gradients One of the more recent studies on this issue concluded that species turnover is higher in temperate regions. latitudinal diversity Latitudinal gradients The latitudinal diversity gradient describes the phenomenon in which the diversity of species inhabiting biomes is higher near the equator and lower near the poles. Faster speciation and reduced extinction in the tropics contribute to … Bird diversity and environmental gradients in Britain Of course, we now refer to the first part of the pattern as the ‘‘latitudinal diversity gradient,’’ and the second as a ‘‘species–area relationship The latitudinal diversity gradient is the most dramatic & robust pattern of species diversity that has been identified. The ‘evolutionary speed’ hypothesis has thus become the explanation for the biodiversity gradient preferred by many molecular biologists. Latitudinal gradients of biodiversity are biogeographic patterns that quantify the ways in which taxonomic, phylogenetic, functional, genetic, or phenetic biodiversity change with latitudinal position on the surface of the earth (Fig. Best known as the latitudinal diversity gradient (LDG), numerous empiri- What is latitudinal gradient? - AskingLot.com Out of the Tropics: Evolutionary Dynamics of the ... On the origin of latitudinal diversity gradients We make two key assumptions. Read on to learn more about existing hypotheses that attempt to explain why this gradient exists, and how scientists may benefit from considering more than one hypothesis at a… A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. 1. no one compelling (consensual) explanation 2. hypothesis not mutually exclusive. Despite a large body of work investigating both geographic and environmental drivers, biogeographical provinces have not been included in statistical models of diversity patterns. Three kinds of explanations have been proposed for the gradient: ecological hypotheses that focus on mechanisms of species coexistence and the maintenance of species diversity (Fig. using the latitudinal gradient in North American tree diversity Paul V.A. Because of the tilt of the earth on its axis, the tropics receive direct solar energy for a greater proportion of the year compared to higher latitudes (temperate and polar zones). Why Is There A Latitudinal Gradient In Temperature On Earth? Latitudinal gradients in species diversity - Wikipedia Latitudinal gradients Examples of marine reverse latitudinal species diversity gradients have been noted but are relatively uncommon (Kiel & Nielsen, 2010). Assessing latitudinal gradients in speciation rates and biodiversity at the global scale. Given the myriad ways biological diversity can overlap in space, understanding the distribution of range sizes may help use reduce the number of diversity hypotheses we have to test. Processes that can produce latitudinal gradients in the diversity of stream invertebrate assemblages are demonstrated, indicating that flood disturbance varying with latitude may influence abundance and local extinction rates of rare species, consequently affecting … As only three processes (specia-tion, extinction and dispersal) can directly affect species richness in areas, similar factors may be responsible for both classical (high tropical diversity) and inverse (high temperate diversity) gradients. Climate is the most often cited explanation of the latitudinal species diversity gradient. Introducing the LDG. biotic hypotheses contributing to latitudinal diversity gradient. instead seek a general explanation for the slope (b) of the LDG (Log 10 S a b Latitude, where S is the number of taxa from a given clade in a fixed area, and a is the esti-mated number of taxa found at the equator) and test this explanation with a standardized dataset. Latitudinal species diversity gradients (LSDGs) are among the most conspicuous biogeographic patterns on Earth. The latitudinal diversity gradient (LDG) is one of Earth’s most iconic biodiversity patterns and still one of the most debated. Thus, a modified explanation for differential Here we review two major hypotheses for the origin of the latitudinal diversity gradient. Determining the evolutionary causes of this pattern remains a challenging task. The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology. The pattern of having lots of species at the equator with diversity dwindling off towards the poles is known as the Latitudinal Diversity Gradient — “latitudinal” meaning how far north or south of the equator, “diversity” meaning the number of species, and “gradient” meaning the transition between high and low. Observed 2007). Allen, A. P., and Gillooly, J. F. 2006. Species diversity is higher at the equator than at the poles. Chaetoceros castracanei, C. flexuosus, C. criophilus, Porosira mechanisms have been proposed to explain latitudinal pseudodenticulata, Fragilariopsis curta). forming inverse latitudinal biodiversity gradients. to explain this latitudinal diversity gradient [10,11], the number of species in a given clade and region is ultimately explained by four major components: the time since the clade colonized the region, speciation rates, extinction rates, and dispersal events [12]. The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology. 1993). the decrease in species richness as one moves away from the equator. The latitudinal diversity gradient (LDG) is one of the most widely studied patterns in ecology, yet no consensus has been reached about its underlying causes. Nature 405: 220-227. A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. In ecology, r/K selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The latitudinal gradient in species diversity is one of the most striking biogeographic patterns in nature, with species richness peaking in equatorial regions for nearly all groups. Latitudinal diversity gradients are among the most striking patterns in nature. The latitudinal diversity gradient (LDG) is one of Earth’s most iconic biodiversity patterns and still one of the most debated. Biotic interactions are believed to play a role in the origin and maintenance of species diversity, and multiple hypotheses link the latitudinal diversity gradient to a presumed gradient in the importance of biotic interactions. 4 Differential contribution of mammalian orders to the latitudinal gradient of species richness in the New World based on data from 5 degree latitudinal bands. ers on time as an explanation for the latitudinal diversity gradient has waxed and waned over the years (Stephens & Wiens, 2003), re-cent studies that have inferred colonization and diversification his-tory simultaneously have found a strong role for time in explaining richness patterns (Economo et al., 2018; Jansson et al., 2013; Li & in diversity and that may enhance latitudinal gradients secondarily, but on the primary cause(s) of the lat-itudinal gradients, if such causes do indeed exist. In biological terms, this is referred to as the latitudinal diversity gradient (LDG), in which the number of species increases from the poles to the Equator. In 2008, we measured richness and … Hence, … All find some support, but also some counterexamples. Latitudinal gradients in regional species richness are a commonly observed pattern in diverse taxonomic groups in a range of habitats (e.g., Rosenzweig 1995; Gaston & Blackburn 2000; Hillebrand 2004a).In general, although latitudinal gradients in species richness are clear and their slope is steep at very large spatial scales (e.g., a regional community: Cornell & … probably the first documented geographical pattern in ecology, as well as an explanation for it that differs from some modern explanations only by lacking an evolutionary component. We examined the applicability of three versions of the energy hypothesis, the habitat heterogeneity hypothesis, and historical contingency to the gradient of terrestrial birds. There have been multiple hypotheses proposed for explaining the EDG, none of which accurately describe the phenomenon in full. The latitudinal gradient in diversity (LDG) remains one of the most well-known but least-understood patterns in ecology and evolution (Willig et al., 2003; Hillebrand, 2004).A phylogenetic perspective is increasingly recognized as crucial for a mechanis-tic explanation (Wiens & … Here we address whether biotic interactions are more important at low latitudes, finding support for this hypothesis from a wide range of interactions. We tested an environmental stress model (ESM) that predicts a unimodal pattern for total richness and diversity in local communities across the full stress gradient where a regional biota can occur. But our documentation of a latitudinal gradient in bacteria suggests otherwise. Latitudinal diversity gradients are among the most striking patterns in nature. The study of biological processes across latitudinal gradients has uncovered one of the most robust natural clines from which ecological and biogeographic patterns can be deduced. Keywords Climate change, evolutionary time, extinction, latitudinal gradient, mean root distance, New World birds, palaeoclimate, species diversity, species. Despite lack of consensus on the issue, some evolutionary ecologists including Brown & Lomolino 1998, Farrell et al. la), evolutionary hypotheses that focus on rates of The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology. Running head: Metabolic theory explains fish diversity Title: The metabolic theory of ecology convincingly explains the latitudinal diversity gradient of Neotropical freshwater fish DAYANI BAILLY1, FERNANDA A. S. CASSEMIRO2, CARLOS S. AGOSTINHO3, ELINEIDE E. MARQUES4 AND ANGELO A. AGOSTINHO State University of Mato Grosso do Sul ­ … The latitudinal diversity gradient (LDG) is the most pernicious of problems. The intermediate disturbance hypothesis (IDH) suggests that local species diversity is maximized when ecological disturbance is neither too rare nor too frequent. The pattern of increasing biological diversity from high latitudes to the equator [latitudinal diversity gradient (LDG)] has been recognized for > 200 years. Gaston, K .J. @article{osti_1357327, title = {A latitudinal diversity gradient in terrestrial bacteria of the genus Streptomyces}, author = {Andam, Cheryl P. and Doroghazi, James R. and Campbell, Ashley N. and Kelly, Peter J. and Choudoir, Mallory J. and Buckley, Daniel H.}, abstractNote = {We show that Streptomyces biogeography in soils across North America is influenced by the regional diversification … Thus, Fischer’s (1960) explanation for the latitudinal 2007 Blackwell Publishing Ltd/CNRS Review and Synthesis Evolution and the latitudinal gradient 317 Table 1 Evolutionary hypotheses for the latitudinal diversity unnecessary in generating the latitudinal diversity gradient, if gradient. We examined the applicability of three versions of the energy hypothesis, the habitat heterogeneity hypothesis, and historical contingency to the gradient of terrestrial birds. Diversity of New World mammals: Universality of the latitudinal gradients of species and bauplans. For this reason, papers and books dealing exclusively with local diversity, such as Tilman (1982, 1988), Janzen (1987), Hubbell et al. igin and maintenance of the latitudinal diversity gradient (Jablonski et al. According to Charles J. Krebs (1994), there are three main groups of proposed hypotheses that Elevational diversity gradient (EDG) is an ecological pattern where biodiversity changes with elevation.The EDG states that species richness tends to increase as elevation increases, up to a certain point, creating a "diversity bulge" at middle elevations. Abstract. Fish were collected from intertidal pools and subtidal habitats (<35 m). Latitudinal diversity gradients (LDG) and their explanatory factors are among the most challenging topics in macroecology and biogeography. This pattern is known as the latitudinal diversity gradient, or LDG. The pattern of having lots of species at the equator with diversity dwindling off towards the poles is known as the Latitudinal Diversity Gradient — "latitudinal" meaning how far north or south of the equator, "diversity" meaning the number of species, and "gradient" meaning the transition between high and low. The pattern of having lots of species at the equator with diversity dwindling off towards the poles is known as the Latitudinal Diversity Gradient — “latitudinal” meaning how far north or south of the equator, “diversity” meaning the number of species, and “gradient” meaning the transition between high and low. Empirical studies have documented this pattern across many different organisms and locations. latitudinal diversity gradients among taxa is great, requiring explanation (MacPherson, 2002). Three kinds of explanations have been proposed for the gradient: ecological hypotheses that focus on mechanisms of species coexistence and the maintenance of species diversity (Fig. The tropical conservatism hypothesis has been proposed as a general explanation for the latitudinal diversity gradient that links the ecological factors correlated with species richness patterns (e.g., climate) to the evolutionary and biogeographic processes that ultimately cause these patterns (e.g., speciation, continental‐scale dispersal). Environmental stress affects species richness and diversity in communities, but the precise form of the relationship is unclear. The increase in species diversity with decreasing latitude, or high tropical species richness, is an ecological pattern that has long intrigued naturalists1. 1a), evolutionary hypotheses that focus on rates of A review is given of recent work on latitudinal gradients in species diversity and their explanations, including Rapoport's rule. A recent attempt to explain latitudinal diversity patterns (Stevens, 1989;Ruggiero, 1994; but note exceptions and problems in Rohde et al., 1993;Rohde, 1996;Lyons and Willig, 1997) invokes a correlation between geographical range of species and the environmental variability within that range. depth diversity gradient The increase in species richness with increasing water depth until about 2000 meters below the surface, where species richness begins to decline. We examined the applicability of three versions of the energy hypothesis, ... developed for plant diversity gradients, offers a parsimonious explanation for bird diversity patterns as well, presumably operating via plant productivity. IntroductionOne of the grand scale ecological patterns is a latitudinal gradient in species richness. Nonetheless, notable exceptions to the general pattern exist, and it is well recognized that patterns may be dependent on characteristics of spatial scale and taxonomic hierarchy. We note that one group of marine protists, planktonic foraminiferans, have long been known to have a global latitudinal gradient of diversity , with 90% of the variability explained by temperature . (1990), and Wilson (1990) and turris) and the northern limit of several cold-water species Several historical, evolutionary and ecological (e.g. But our documentation of a latitudinal gradient in bacteria suggests otherwise. A latitudinal diversity gradient in planktonic marine bacteria Jed A. Fuhrman, Joshua A. Steele, Ian Hewson, Michael S. Schwalbach, Mark V. Brown, ... consensus explanation (1-6). We analyzed latitudinal ranges of 2838 eastern Pacific marine molluscan species, a subset of which figured in the original formulation of Rapoport's rule, and failed to find the predicted trends. Surprisingly though, after decades of study, a universally accepted explanation for the latitudinal diversity gradient remains elusive. Hypotheses have 8 ultimately invoked either faster rates of diversification in the tropics, or more time for The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. A latitudinal diversity gradient in planktonic marine bacteria Jed A. Fuhrman*†, Joshua A. Steele*, Ian Hewson*, Michael S. Schwalbach*, Mark V. Brown*, Jessica L. Green†‡, and James H. Brown†§ *Wrigley Institute for Environmental Studies and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0371; generate and/or maintain inverse latitudinal diversity gradients. Despite of its apparent generality, a growing body of evidence shows that ‘anomalous’ LDG (i.e., inverse or hump-shaped trends) are common among marine organisms along the Southeastern Pacific (SEP) coast. 1. spatial heterogeneity hypothesis 2. competition hypothesis 3. predation hypothesis 4. mutualism and coevolution hypothesis. According to Charles J. Krebs (1994), there are three main groups of proposed hypotheses that latitudinal gradient in species richness, the latitudinal gradient in species geographical range size (Rapoport’s rule), species geographical range boundaries and patterns of invasion in the tropics. The latitudinal gradient in species richness is perhaps the most fundamental pattern of biodiversity, yet a satisfactory explanation for its existence remains elusive. There are multiple theories as to why this is the case. While, just as with the latitudinal diversity gradients, the explanations are typically empirical data to assess whether the diversity patterns of fish fauna along 4000 km of the Chilean coast (20°â€“55° S) can be explained in relation to the environmental latitudinal gradient. Surprisingly though, after decades of study, a universally accepted explanation for the latitudinal diversity gradient remains elusive. We note that one group of marine protists, planktonic foraminiferans, have long been known to have a global latitudinal gradient of diversity , with 90% of the variability explained by temperature . This method was called the midpoint method. Although many of the hypotheses exploring the latitudinal diversity gradient are closely related and interdependent, most of the major hypotheses can be split into three general hypotheses. Research on global patterns of diversity has been dominated by studies seeking explanations for the equator-to-poles decline in richness of most groups of organisms, namely the latitudinal diversity gradient. However, summer temperature is the best overall explanation for bird diversity ... the latitudinal diversity gradient shown by most taxonomic groups. Academia.edu is a platform for academics to share research papers. … Latitudinal gradients in species diversity: the search for the primary cause. Oikos 65 514–527 10.2307/3545569 [Google Scholar] Rolland J., Condamine F. L., Jiguet F., Morlon H. (2014). Adapted from Roy et al 1998 Figure 2616 Latitudinal patterns of species richness from ECOLOGY SC260.1.1 at Ashworth College Because γ diversity varies along both latitudinal and elevational gradients, its influence on α and β diversity must be accounted for before any ecological explanations are offered. 2000. 2006; Mittelbach et al. Rohde, K. 1999. At low levels of disturbance, more competitive organisms will push subordinate species to extinction and dominate the ecosystem. The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology. explanation for the latitudinal diversity gradient remains elusive. gradients in species richness (e.g. Despite lack of consensus on the issue, some evolutionary ecologists including Brown & Lomolino 1998, Farrell et al.

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