1. ecological/evolutionary time hypothesis Title: Latitudinal Diversity Gradient Hypothesis, the state of knowledge By Schibon. A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. Barton et al., 2010; The latitudinal . Abundance and diversity of birch‐feeding leafminers along ... The time theory Ecology and evolution 2. As early as 1807, von Humboldt provided the first formulation for . that β-diversity of forest soil microbes across a large latitudinal tem - perature gradient, from subalpine Colorado to tropical Panama, was strongly correlated with temperature (Deng et al., 2018). What causes latitudinal gradients in species diversity ... The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. What causes latitudinal gradient? To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering evolutionary processes indirectly. Evolution and the latitudinal diversity gradient ... Patterns in Palaeontology: The latitudinal biodiversity ... biotic hypotheses contributing to latitudinal diversity gradient. Here we review two major hypotheses for the origin of the latitudinal diversity gradient. Therefore, the ecological explanations proffered are usually specific to the group in question. Since the tropics are so much larger than any other extra-tropical biome, one would predict the latitudinal gradient to resemble a step . Keywords:latitudinal diversity gradient; marine bivalves; species^energy hypothesis 1. 1. (1990), and Wilson (1990) and 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. 2003) Source Encyclopedia of biodiversity and Willig et al. Evolution of the latitudinal diversity gradient in the ... In angiosperms, the tropical conservatism hypothesis proposes that most groups originated in the tropics and are adapted t … This pattern is a one of the most and oldest primary trends concerning life's species on earth. Introducing the LDG. Using marine bivalves as a model system and drawing on other systems where possible, we review paleobiologic . Introducing the LDG - Understanding Evolution (PDF) Latitudinal diversity patterns of diatoms in the ... 2 The latitudinal gradient. Here we review two major hypotheses for the origin of the latitudinal diversity gradient. The theory of spatial heterogeneity: Ecology 3. Latitudinal Diversity Gradient, Geographical, Species, Species Richness, Taxa, Hypothesis,Biotic, Historical Perturbation, Climate Stability, Climate Harshness, Mid-Domain, Evolutionary Rate, Evolution. We examined the applicability of three versions of the energy hypothesis, the habitat heterogeneity hypothesis, and historical contingency to the gradient of terrestrial birds. We examined the applicability of three versions of the energy hypothesis, the habitat heterogeneity hypothesis, and historical contingency to the gradient of terrestrial birds. and ecological causes of the latitudinal diversity gradient and to test the major predictions of the tropical conser-vatism hypothesis. Latitudinal gradients in species diversity are generally understood to be increases in the number of species from high (cold-temperate) to low (warm) latitudes (Rohde, 2011). 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 . The time and4 area hypothesis holds that tropical climates are older and historically larger, allowing more (doi:10.1086/507882). the highest numbers of species in the tropics and gradual decrease poleward) is a well-recognized and long established pattern in terrestrial ecology. The time and area hypothesis holds that tropical climates are o … 553-560. A latitudinal gradient in species richness, defined as a decrease in biodiversity away from the equator, is one of the oldest known patterns in ecology and evolutionary biology. Abstract The latitudinal gradient of decreasing richness from tropical to extratropical areas is ecology's longest recognized pattern. Biodivers. area-affect hypothesis, at least for latitudinal gradients in marine systems. As only three processes (specia- Some of the . The predation hypothesis: Ecology 5. microhabitats). Acrididae, grasshopper, latitudinal diversity gradient, spatial heterogeneity hypothesis, species diversity. Introduction. With this notation, it can easily be seen that a latitudinal gradient in richness, with D T 9 D E, The latitudinal diversity gradient Key concepts • The latitudinal diversity gradient • Mid-domain e↵ect • Niche conservatism and niche evolution • Biotic theories Introduction Figure 1: New World birds, including hummingbirds, exhibit higher species richness in tropical latitudes The productivity version of the energy hypothesis, tested using actual . INTRODUCTION One of the most striking of large-scale biotic patterns is the latitudinal gradient in species diversity, peaking in the tropics and tailing o¡ towards the poles. The latitudinal gradient of species diversity among North American grasshoppers (Acrididae) within a single habitat: a test of the spatial heterogeneity hypothesis Goggy Davidowitz Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, U.S.A. We found insect diversity at McAbee to be more similar to La Selva than to Harvard Forest, with high species richness of most groups and decreased diversity of ichneumon wasps, indicating that seasonality is key to the latitudinal diversity gradient. 1. spatial heterogeneity hypothesis 2. competition hypothesis 3. predation hypothesis 4. mutualism and coevolution hypothesis. 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 . The existing hypotheses explaining this phenomenon are summarized and the evidence that tends to favor one of these is presented. The latitudinal diversity gradient (LDG) is the most pernicious of problems. One of the oldest and most fundamental patterns concerning life on earth (Willig et al. The pre-dominance of single-gradient studies counteracted the no-tion of generality within the latitudinal diversity debate. Oikos 1992, 65, 514-527. Figure 1 — An example of the modern latitudinal biodiversity gradient, showing the distribution of living terrestrial vertebrate species, with the highest concentration of diversity found in equatorial regions (red end of the colour spectrum) and declining polewards (blue end) to form the modern pattern. In: Journal of Biogeography . A similar pattern has been postulated for marine biota. A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. gradients in species richness (e.g. Determining the evolutionary causes of this pattern remains a challenging task. An abundance of microhabitats allows taxa to partition each On the local scale, the spatial heterogeneity hypothesis suggests that the tropics contain more habitat subdivisions (i.e. The latitudinal gradient in global diversity, in which the number of species decreases away from the tropics, is widely recognized and well-studied but no consensus exists as to its cause. The time theory: Ecology and evolution 2. Moreover, the main focus has been on vertebrate taxa and higher plants, and a ma-jority of studies originated from the Americas. This hypothesis posits that the size of a biome has considerable influence on its species diversity. Chaetoceros castracanei, C. flexuosus, C. criophilus, Porosira mechanisms have been proposed to explain latitudinal pseudodenticulata, Fragilariopsis curta). Methods We used digitized range maps of breeding birds to estimate the species richness at two grain sizes, 756 and 12,100 km2. for plants, bats, mammalian quadrupeds, reptiles or termites . and ecological causes of the latitudinal diversity gradient and to test the major predictions of the tropical conser-vatism hypothesis. tropical conservatism hypothesis). Another climate-related hypothesis is the climate harshness hypothesis, which states the latitudinal diversity gradient may exist simply because fewer species can physiologically tolerate conditions at higher latitudes than at low latitudes because higher latitudes are often colder and drier than tropical latitudes. @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 of . Hypothesis Our interpretation of the main focus; Pianka 1966: 1. The pattern is . 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 . 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 . It is evident that an increase in biological It was documented e.g. Our study was designed to verify this hypothesis by exploring latitudinal patterns in abundance and diversity of birch-feeding insect herbivores belonging to the leafminer guild in northern Europe, from 59° to 69°N. The hypothesis that the Tropics are either a diversity source or sink can be tested by comparing FAD and LAD latitudes. The global increase in species richness toward the tropics across continents and taxonomic groups, referred to as the latitudinal diversity gradient, stimulated the formulation of many hypotheses . hypothesis for the bird latitudinal diversity gradient derived from the effects of niche conservatism in the face of global climate change over evolutionary time. There is rather weak knowledge of how ecological and Support for this hypothesis 5. Contrary to the anti-tropical diversity pattern of modern articulated brachiopods, Paleozoic terebratulides show a latitudinal diversity gradient that peaks in the Tropics. In fact, well over 30 hypotheses / environmental, evolutionary, and stochastic / have been advanced to account for empirical patterns in the latitudinal gradient of diversity (Willig et al. [Google Scholar] the latitudinal gradient of species richness (Rohde 1992, Rosenzweig 1995, Brown and Lomolino 1998, Willig 2000, Schemske 2002). For example, low species diversity is known to occur often in stable environments such as tropical mountaintops. Climate is widely recognised as an important determinant of the latitudinal diversity gradient. Additionally, many habitats with high species diversity do experience seasonal climates, including many tropical regions that have highly seasonal rainfall (Brown and Lomolino 1998). 168, 579-596. Here we address whether biotic interactions are more important at low latitudes, finding support for this hypothesis from a wide range of interactions. 36 The latitudinal diversity gradient is the dominant pattern of life on Earth, but a consensus 37 understanding of its origins has remained elusive. The time and area hypothesis holds that tropical climates are older and historically larger, allowing more
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