A parallel trend has been found with elevation (elevational diversity . Determining the evolutionary causes of this pattern remains a challenging task. To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering . The decline of biodiversity with latitude has received great attention, but both the concise pattern and the causes of the gradient are under strong debate. 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 taxon richness and taxon diversity. 1993). The fact that many of the species-rich tropical marine environments are high in temperature but relatively low in productivity suggests that kinetic mechanisms play a primary . The extent of latitude influences the outcome. It has been >200 years since the latitudinal diversity gradient was first described (Humboldt and Bonpland 1807), but its causes remain poorly understood (Mittelbach et al . As noted above, origination rates are highest in the more diverse regions and taxa variables that have often been cited as influencing the latitudinal diversity gradient directly or as being associated with factors that have direct effects on physiology related to survival and reproduction (such as potential evapotransporation 5,27). (1990), and Wilson (1990) and The LDG has been observed to varying degrees in Earth's past. 1. doesn't explain why more species coexist in tropics in first place. To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering . All find some support, but also some counterexamples. 1. doesn't explain why more species coexist in tropics in first place. Ecology Letters (2012) The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. Herbaceous species evolved in younger vegetation types at . Additionally, many habitats with high species diversity do experience seasonal climates, including many tropical regions that have highly . As gradients of species richness were often explained by ambient temperature (15, 16), and mean temperature decreases with elevation , it followed that the elevational species richness gradient should merely be a mirror of the latitudinal gradient, with decreasing richness from lowlands toward high elevations mirroring the decrease in richness . To address this issue, previous LDG studies have usually relied on correlations between environmental variables and … The latitudinal diverseness gradient is the term used to depict the lessening in species richness as one moves off from the equator. Data resources used via GBIF : 356 taxa. Latitudinal gradients in species diversity Species richness, or biodiversity, increases from the poles to the tropics for a wide variety of terrestrial and marine organisms, often referred to as the latitudinal diversity gradient (LDG) [1].The LDG is one of the most widely recognized patterns in ecology [1].The LDG has been observed to varying degrees in Earth's past. cannot be proximate cause of the latitudinal diversity gradient as they beg the question of why species interactions might be stronger in the tropics. Accordingly, what causes latitudinal gradient? Some groups of organisms, however, show an opposite trend: a strong latitudinal decline in species diversity towards the tropics. Our study shows that the shape of marine LDGs changed substantially and rapidly during the Permian-Triassic mass extinction from a modern-like steep LDG . 3. with fewer species there is more generalized niche use. This method was called the midpoint method. Over-exploitation, pollution and habitat conversion are the main threats to species diversity. An example of one such hypothesis is the greater intensity of predation and more specialized predators in the tropics has contributed to the increase of diversity in the tropics (Pianka 1966). Another major problem with Rapoport's rule con-cerns the relationships between the latitudinal diversity gradient, latitudinal trends in potential range extents, and observed patterns (Kolasa et al. Understanding . the latitudinal gradient in species diversity in a variety of taxa. LETTER Direct and indirect effects of climate on richness drive the latitudinal diversity gradient in forest trees Chengjin Chu,1,* James A. Lutz,2 Kamil Kral, 3Tom asVrska, Xue Yin,1 Jonathan A. Myers,4 Iveren Abiem,5,6,7 Alfonso Alonso,8 Norm Bourg,9,10 David F.R.P. Recent studies have shown that latitudinal differences in speciation and extinction rates give rise to high tropical diversity. 2. habitat breadth decreases as the number of species increases. Determining the evolutionary causes of this pattern remains a . 1998). The 'latitudinal diversity gradient' is the name given to the upsurge in species richness from the poles to the equator. Assignment of causes to past latitudinal gradient changes is problematic due to uncertainties concerning CO 2 and ocean heat transports, but tentative conclusions based on this analysis support the likelihood of a future, higher-CO 2 climate exhibiting a large low-latitude gradient and ample precipitation at middle latitudes. Various hypotheses seek to explain the latitudinal diversity gradient. The influence of other drivers on the latitudinal gradient cannot, therefore, be excluded. A deep-time perspective on the latitudinal diversity gradient. The latitudinal diversity gradient (LDG) is one of the largest scale and longest known patterns in ecology (e.g. [1] Discovered by Alexander von Humboldt in 1799, it has remained one of the key questions in Evolutionary Ecology. Climate stability hypothesis Similarly to the climate harshness hypothesis, climate stability is suggested to be the reason for the latitudinal diversity gradient. Finally, the model results, in conjunction with the results of existingempirical studies, suggest that the nature of macroevolutionary and biogeo- criticisms of competition hypothesis. The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. The latitudinal diversity gradient is the term used to describe the decrease in species richness as one moves away from the equator. Furthermore, intraspecific and interspecies diversity may interact in complex ways. The results are consistent with tropical conservatism explaining the diversity gradient, while providing no evidence that diversification rate varies systematically with latitude, and there is evidence of ecological regulation on continental scales through the pattern of diversification after colonization. PDF. We combine a diversity of analytical approaches (e.g., phylogenetics, ancestral area reconstruc-tion, divergence date estimation, analysis of diversification rates, ecological niche modeling) and focus on New . what causes latitudinal gradient? Here we review two major hypotheses for the origin of the latitudinal diversity gradient. The deep-time dynamics of the latitudinal diversity gradient (LDG), especially through dramatic events like mass extinctions, can provide invaluable insights into the biotic responses to global changes, yet they remain largely underexplored. This latitudinal diversity gradient (LDG) was first recognized by . [1-7]).Modern biodiversity (i.e. The latitudinal diversity gradient (LDG) is the most pernicious of problems. Possible Causes of Latitudinal Diversity Dynamics The genus-level diversity gradient must be explained by some combination oforigination, extinction, and dispersal rates, and recent models have explored interactions among these parameters (see Roy and Goldberg 2007). Differences in measured rates of speciation and extinction among living species are commonly used to explain latitudinal diversity gradients. A meta-analysis by Hillebrand (2004) surveyed more than 600 latitudinal diversity gradient studies and found a small number of exceptions (4.3%) to the general negative relationship. [Google Scholar] Lett. 1996, 3, 10-13. 6 Why does the gradient exist, and is it relevant to conservation biology? To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering evolutionary processes indirectly . Latitudinal diversity gradients (LDG) and their explanatory factors are among the most challenging topics in macroecology and biogeography. 1. local diversity increases. But to understand the ultimate causes of diversity patterns, we must also examine the evolutionary and biogeographic processes that directly change species numbers (i.e., speciation, extinction, and dispersal). 2. habitat breadth decreases as the number of species increases. What caused the latitudinal diversity gradient? (A) β diversity (distance from centroid) and (B) latitudinal turnover gradients (LTG) strength of extant North American mammals under incomplete taxonomic sampling (removal of 25, 50, and 75% of species in sample) and body mass bias (removal of 25, 50, 75% of species smaller than 5 kg) and (C) β diversity (distance from centroid) and (D . The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. Determining the evolutionary causes of this pattern remains a challenging task. [2] 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. These trends have been almost neglected in the literature and little is known about their underlying ecological and evolutionary causes. The time and area hypothesis holds that tropical climates are older and historically larger, allowing more For example, low species diversity is known to occur often in stable environments such as tropical mountaintops. The fact that it is so obvious and so general - the overabundance of species in the tropics was recognized long before there were even ecologists around to describe it - strongly suggests that the explanation should be a simple one; yet distinguishing between alternative simple explanations has proven, well . For this reason, papers and books dealing exclusively with local diversity, such as Tilman (1982, 1988), Janzen (1987), Hubbell et al. what causes latitudinal gradient? Instead, we use a . 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. What causes species diversity? Observed Although there are exceptions, this pattern is pervasive within both the terrestrial and marine realm and across taxonomic groups ( 1 ). Introduction. This idea is also referred to as the latitudinal diversity gradient, meaning that as you move from the equator towards the poles, diversity lessens. The decline of biodiversity with latitude has received great attention, but both the concise pattern and the causes of the gradient are under strong debate. The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. The logic is straightforward: the higher the net diversification rate (the difference between the speciation and extinction rate), the greater the number of species. The questions are ; What causes the latitudinal gradient? criticisms of competition hypothesis. high number of closely-related woody species in rain forests. Most studies of the latitudinal gradient comprise only one or few organism types and are often restricted to certain region or habitat types. What caused the latitudinal diversity gradient? To differentiate seasonality between the forests, we used the summed coefficients of variation Expand. Of the many notable contributions by the Washington group, Eric Pianka's 1966 article "Latitudinal Gradients in Species Diversity: A Review of Concepts" is emblematic of the creative energy at work during this era to address big problems in ecology and evolution. Burslem,11 Min Cao,12 Hazel Chapman,6,7 Richard Condit,13 Suqin Fang,1 Gunter A. Fischer,14 Lianming Furthermore, intraspecific and interspecies diversity may interact in complex ways. To test for significant variation in the gradient between organisms, habitats, A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. Thus, it is critical to include the effects of dispersal when formulating and testing hy-potheses about the causes of large-scale gradients in diversity. The increase in species diversity from the poles to the equator, commonly referred to as the latitudinal diversity gradient (LDG), is one of the most pervasive 1, 2 and widely debated biological patterns, with at least 26 listed hypotheses associated with it 3, 4, 5.These hypotheses can be classified into three higher-level categories related to latitudinal variation in ecological limits (see . Evolution and the latitudinal diversity gradient: speciation, extinction and biogeography Abstract A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. The first is from 197 locations along a latitudinal gradient spanning more than 100° (12, 13), and the second is a similar set of eight locations spanning a 2250-m elevational gradientinCarchi,Ecuador( 14,15).We define a diversity as the species richness of a single .01-ha For example, high species richness can increase intraspecific diversity as a result of increased competition for similar resources . Herbaceous species evolved in younger vegetation types at . Many studies have documented a latitudinal gradient in diversity of marine organisms, including both fish and invertebrates, benthic and planktonic forms (e.g., 15 -18). Understanding the patterns and . However, it is unclear if this gradient is the product of population-level, species-level, or clade-level processes. For example, high species richness can increase intraspecific diversity as a result of increased competition for similar resources . Modeling causes of the latitudinal gradient in species richness}, author = {Taylor, P H and Gaines, S D}, abstractNote = {The latitudinal gradient in species richness, wherein species richness peaks near the equator and declines toward the poles, is a widely recognized phenomenon that holds true for many taxa in all habitat types. The influence of other drivers on the latitudinal gradient cannot, therefore, be excluded. Data resources used via GBIF : 356 taxa. In this vein, J. T. Weir and D. Schluter conclude from their recent study of birds and . 24. 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. Aim The latitudinal diversity gradient is the dominant pattern of life on Earth, but a . Biodivers. One of the more recent studies on this issue concluded that species turnover is higher in temperate regions. Determining the evolutionary causes of this pattern remains a challenging task. 2. not well tested in most groups (hard to test competition) Species richness, or biodiversity, increases from the poles to the tropics for a wide variety of terrestrial and marine organisms, often referred to as the latitudinal diversity gradient (LDG). [Google Scholar] Rohde, K. Rapoport's rule is a local phenomenon and cannot explain latitudinal gradients in species diversity. This study examines stony corals (order Scleractinia), as they have one of the clearest and most exemplary gradients of all clades. 1. Latitudinal Diversity Gradient, Geographical, Species, Species Richness, Taxa, Hypothesis,Biotic, Historical Perturbation, Climate Stability, Climate Harshness, Mid-Domain, Evolutionary Rate, Evolution. changes in a and g diversity, we use two data sets of woody plants. 2. not well tested in most groups (hard to test competition) 1. local diversity increases. Some of the cases (sawflies and bryophytes) were . The latitudinal diversity gradient is the most dramatic & robust pattern of species diversity that has been identified. With this perspective, we dissect the latitudinal diversity gradient in hylid frogs. Climate stability hypothesis Similarly to the climate harshness hypothesis, climate stability is suggested to be the reason for the latitudinal diversity gradient.For example, low species diversity is known to occur often in stable environments such as tropical mountaintops. Oikos 1992, 65, 514-527. Climate stability hypothesis Similarly to the climate harshness hypothesis, climate stability is suggested to be the reason for the latitudinal diversity gradient. richness) gradients are broadly defined as unimodal, with high biodiversity near the equator and low biodiversity at the poles [4,6].The specifics of these gradients differ among taxonomic and ecological groups [2-4,6], and . The latitudinal diversity gradient (LDG) — the decline in species richness from the equator to the poles — is classically considered as the most pervasive macroecological pattern on Earth, but . Click to read in-depth answer. They cause a gradual loss of species on local, regional and global levels. In this way, what causes latitudinal gradients in species diversity? (2003) found that nearly 71% of 135 analyses that had tested latitudinal diversity gradients showed that diversity was higher in the tropics. Introducing the LDG. Although there are exceptions, this pattern is pervasive within both the terrestrial and marine realm and across taxonomic groups ( 1 ). Similarly to the climate harshness hypothesis, climate stability is suggested to be the reason for the latitudinal diversity gradient. This latitudinal diversity gradient (LDG) was first recognized by . 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. This study examines stony corals (order Scleractinia), as they have one of the clearest and most exemplary gradients of all clades. and ecological causes of the latitudinal diversity gradient and to test the major predictions of the tropical conser-vatism hypothesis.

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