hypothesis for the bird latitudinal diversity gradient derived from the effects of niche conservatism in the face of global climate change over evolutionary time. 2003) Source Encyclopedia of biodiversity and Willig et al.
One of the oldest and most fundamental patterns concerning life on earth (Willig et al.
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. 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. 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 . Some of the .
This pattern is a one of the most and oldest primary trends concerning life's species on earth. A variety of hypotheses have been proposed to explain the latitudinal gradients of biodiversity, among which the diversification rate hypothesis argues that generational turnover and speciation . Using a spatially explicit approach that incorporates not only origination and extinction but immigration, a global analysis of genera and subgenera of marine bivalves over the past 11 million years supports an "out of the tropics" model, in which taxa preferentially . tropical conservatism hypothesis). Moreover, the main focus has been on vertebrate taxa and higher plants, and a ma-jority of studies originated from the Americas. However, most existing studies make no distinction between direct and indirect effects of climate . In the second hypothesis, known as the "tropical niche conservatism" hypothesis, lineages originate in the tropics and have difficulties to disperse and adapt into temperate regions, thus accumulating in . The competition hypothesis . The latitudinal diversity gradient is the term used to describe the decrease in species richness as one moves away from the equator. 25, No.
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. Support for this hypothesis Abstract An impediment to understanding the origin and dynamics of the latitudinal diversity gradient (LDG)—the most pervasive large-scale biotic pattern on Earth—has been the tendency to focus narrowly on a single causal factor when a more synthetic, integrative approach is needed. The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology. The theory of spatial heterogeneity Ecology 3. Latitudinal Gradients in Species Diversity 000 Table 1: Pianka's (1966) six hypotheses and Fine's (2015) five hypotheses for the latitu-dinal diversity gradient Hypothesis Our interpretation of the main focus Pianka 1966: 1. The latitudinal diversity gradient is among the most well-known patterns in ecology (Hillebrand, 2004; Jocque et al., 2010).While general patterns of increasing richness from the poles to the equator are common, there are many exceptions (Gaston & Blackburn, 2000; Hillebrand, 2004; Heino, 2011).The potential mechanisms behind this gradient are broad, whether non-biological (e.g . (doi:10.1086/507882). Acrididae, grasshopper, latitudinal diversity gradient, spatial heterogeneity hypothesis, species diversity. 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.
We conducted an extensive survey of the literature and provide a synthetic . Keywords:latitudinal diversity gradient; marine bivalves; species^energy hypothesis 1. The latitudinal diverseness gradient is the term used to depict the lessening in species richness as one moves off from the equator. The predation hypothesis: Ecology 5. 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. abiotic hypotheses contributing to latitudinal diversity gradient. 2006 Evolutionary and ecological causes of the latitudinal diversity gradient in hylid frogs: treefrog trees unearth the roots of high tropical diversity. In angiosperms, the tropical conservatism hypothesis proposes that most groups originated in the tropics and are adapted t … 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. We then used molecular 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). Nat. Latitudinal Gradients in Species Diversity 000 Table 1: Pianka's (1966) six hypotheses and Fine's (2015) five hypotheses for the latitu-dinal diversity gradient Hypothesis Our interpretation of the main focus Pianka 1966: 1. 3. pp. Chaetoceros castracanei, C. flexuosus, C. criophilus, Porosira mechanisms have been proposed to explain latitudinal pseudodenticulata, Fragilariopsis curta). Crossref, PubMed, ISI, Google Scholar A similar pattern has been postulated for marine biota. 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 . We examined the applicability of three versions of the energy hypothesis, the habitat heterogeneity hypothesis, and historical contingency to the gradient of terrestrial birds. However, there are also many known cases of increasing poleward diversity, forming inverse latitudinal biodiversity gradients. For example, low species diversity is known to occur often in stable environments such as tropical mountaintops. The latitudinal species richness gradient in New World woody angiosperms is consistent with the tropical conservatism hypothesis Andrew J. Kerkhoffa,1, Pamela E. Moriartya,b, and Michael D. Weiserc aDepartments of Biology and Mathematics and Statistics, Kenyon College, Gambier, OH 43050; bSchool of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98105; and cDepartment of . Title: Latitudinal Diversity Gradient Hypothesis, the state of knowledge By Schibon. 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. 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.
microhabitats). If particular higher taxa are monophyletic and of tropical origin and diversify along latitudinal gradients according to a historical process such as the one presented, then the five aforementioned predictions should hold with respect to distance from As early as 1807, von Humboldt provided the first formulation for .
To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering evolutionary processes indirectly. The hypothesis that the Tropics are either a diversity source or sink can be tested by comparing FAD and LAD latitudes. 1996, 3, 10-13. A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. It was documented e.g. Pianka's (1966) six hypotheses and Fine's (2015) five hypotheses for the latitudinal diversity gradient. The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology.
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