The "Age of the Tropics" hypothesis argues that the tropics have more species because young, ecologically dominant, tropical clades have not had sufficient time to disperse and adapt to colder climates . As early as 1807, von Humboldt provided the first formulation for . 4) , latitudinal gradients in shell costs are less clear . While there are latitudinal trends in proportional shell size (inorganic content; Fig. 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. As early as 1807, von Humboldt provided the first formulation for . Introduction.
Additionally, many habitats with high species diversity do experience seasonal climates, including many tropical regions that have highly seasonal rainfall (Brown and Lomolino 1998). 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… The Latitudinal Gradient in Niche Breadth: . Title: Latitudinal Diversity Gradient Hypothesis, the state of knowledge By Schibon. Instead, the probability of a bird being infected with Leucocytozoon . A third proposed explanation for the latitudinal diversity gradient holds that the pattern depends upon total or average amount of available energy (often taken as a function of solar radiation at the surface) (4, 21, 22). Climate is widely recognised as an important determinant of the latitudinal diversity gradient.
Testing the hypothesis of loss of defenses on islands across a wide latitudinal gradient of Periploca laevigata populations Pedro Monroy1 and Carlos García-Verdugo1,2,3 RESEARCH ARTICLE Manuscript received 25 August 2018; revision accepted 19 November 2018. - Oikos 65: 514-527. The time and area hypothesis holds that tropical climates are o … Keywords: biogeography, latitude, biodiversity, kinetics, ARISA. EMS is an approach used to explore and characterise emergent properties in a site-by-species matrix, using three metrics: (1) coherence, or the degree to which . By modulating interactions between species, latitudinal gradients may also shape food-web structure. This idea has been influential and long standing, yet no studies have evaluated its generality or the validity of its . Introduction. Pianka's (1966) six hypotheses and Fine's (2015) five hypotheses for the latitudinal diversity gradient. 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. Seasonality, the latitudinal gradient of diversity, and Eocene insects - Volume 36 Issue 3 area-affect hypothesis, at least for latitudinal gradients in marine systems. Here, we use geographic and evolutionary data for over 12,500 species of woody flowering plants to test the "tropical conservatism hypothesis," which attributes the . [2] 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. 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. Latitudinal Diversity Gradient, Geographical, Species, Species Richness, Taxa, Hypothesis,Biotic, Historical Perturbation, Climate Stability, Climate Harshness, Mid-Domain, Evolutionary Rate, Evolution. Here we review two major hypotheses for the origin of the latitudinal diversity gradient. (4) Finally, the tropical stability hypothesis argues that climatic fluctuations and glacial cycles in extratropical regions have led to greater extinction rates and less opportunity for specialization relative to the tropics. ABSTRACT Birds display a latitudinal gradient in clutch size. [1] Discovered by Alexander von Humboldt in 1799, it has remained one of the key questions in Evolutionary Ecology. 1).Historically, research has focused on gradients of species richness (i.e., the number of species in an assemblage) because that was the only information . Our findings are consistent with a latitudinal gradient in primate dispersal limitation and support the hypothesis that there are trade-offs in dispersal ability and ecological specialization, which in turn offers an explanation for the Rapoport effect, which is the pattern observed when geographic range sizes increase with distance from the . 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). 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. This would be a fruitful area for research, given the diversity of physical defences (e.g. 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 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 . The empty niches hypothesis makes no clear prediction about latitudinal gradients 76 in the strength of competition between close relatives. Geographic area hypothesis One of the most basic ideas that have been offered to account for the latitudinal gradient of species richness is embodied in the geographic area hypothesis. Because shell cost is a fairly small component of the energy budget, it may be expected to play a smaller role in explaining latitudinal gradients in proportional shell size compared with other . An evaluation of the geographic area hypothesis using the latitudinal gradient in North American tree diversity Paul V.A. 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. Expert Answer. The evolutionary dynamics underlying the latitudinal gradient in biodiversity have been controversial for over a century. The Latitudinal Biotic Interaction Hypothesis (LBIH) states that the intensity of biotic interactions increases from high to low latitudes. spines, thorns, hairs, trichomes, sclerites and silica), their importance in deterring herbivores . The time theory: Ecology and evolution 2. We . 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. The gradient of increasing species richness with decreasing latitude is one of the most well-established patterns in macroecology and is pervasive in time and space, and pertains to all major taxa. Incidence and prevalence of ulcerative colitis follow a north-south (latitudinal) gradient and increases northwards at the northern hemisphere or southwards at the southern hemisphere. Abstract The latitudinal gradient of decreasing richness from tropical to extratropical areas is ecology's longest recognized pattern. the latitudinal gradient in human language richness and mean language range size. The latitudinal diverseness gradient is the term used to depict the lessening in species richness as one moves off from the equator. Latitudinal diversity gradients in bryophytes and woody plants: Roles of temperature and water availability Sheng-Bin Chen 1,2 , J. W. Ferry Slik 2 , Jie Gao 3 , Ling-Feng Mao 4 , Meng-Jie Bi 5 , Meng-Wei Shen 6 , and Ke-Xin Zhou 1 * 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. Under this hypothesis, dispersal is higher out of than into the tropics, thus acting "against" the latitudinal diversity gradient. Fine* Department of Biology, University of Utah, 257 S. 1400 East, Room 201, Salt Lake City, UT 84112, USA ABSTRACT One hypothesis to explain the latitudinal gradient in species diversity is the geographic area hypothesis. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Accordingly, what causes latitudinal gradient? Latitudinal diversity gradients (LDG) and their explanatory factors are among the most challenging topics in macroecology and biogeography. Here we address whether biotic interactions are more important at low latitudes, finding support for this hypothesis from a wide range of interactions. Support for this hypothesis Evidence for and against the latitudinal herbivory-defence hypothesis. Introduction. 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 . A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. The literature on latitudinal gradients in physical defences is much sparser than the literature on latitudinal gradients in herbivory or chemical defences. The latitudinal diverseness gradient is the term used to depict the lessening in species richness as one moves off from the equator. Geographic area hypothesis One of the most basic ideas that have been offered to account for the latitudinal gradient of species richness is embodied in the geographic area hypothesis. spines, thorns, hairs, trichomes, sclerites and silica), their importance in deterring herbivores . Here an account of the most important cases of inverse latitudinal gradients is given. The disease has increased during the last decades. Some of the . The theory of spatial heterogeneity: Ecology 3. Fine* Department of Biology, University of Utah, 257 S. 1400 East, Room 201, Salt Lake City, UT 84112, USA ABSTRACT One hypothesis to explain the latitudinal gradient in species diversity is the geographic area hypothesis. pose an alternative hypothesis leading to a latitudinal gra-dient in niche breadth, which we believe is more com-patible with our current understanding of community assembly and of general latitudinal patterns of biodiversity. (3) The speciation rates hypothesis suggests that the latitudinal gradient arises from a gradient in speciation rates. This would be a fruitful area for research, given the diversity of physical defences (e.g. This hypothesis, which may partly explain latitudinal gradients in biodiversity, remains hotly debated, largely due to variable outcomes of published studies. This hypothesis, which may partly explain latitudinal gradients in biodiversity, remains hotly debated, largely due to variable outcomes of published studies. The fundamental proposition is that tropical zones Introduction. The impressive diversity of species in the tropics, contrasted against comparatively depauperate temperate and arctic ecosystems, is among nature's most striking biogeographic patterns (Dobzhansky, 1950).It is hypothesized that this gradient in diversity is in part explained by the ecological and evolutionary consequences . This idea has been influential and long standing, yet no studies have evaluated its generality or the validity of its assumptions. 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. The diversity of living things generally peaks in the tropics and declines toward the poles. Indeed, these latitudinal environmental gradients have been put forward as potential drivers for the latitudinal gradient in species richness, one of the most general and robust patterns in ecology [16,19,20]. However, there are also many known cases of increasing poleward diversity, forming inverse latitudinal biodiversity gradients. One hypothesis to explain the latitudinal gradient in species diversity is the geographic area hypothesis. The literature on latitudinal gradients in physical defences is much sparser than the literature on latitudinal gradients in herbivory or chemical defences. Title: Latitudinal Diversity Gradient Hypothesis, the state of knowledge By Schibon. Burslem,11 Min Cao,12 Hazel Chapman,6,7 Richard Condit,13 Suqin Fang,1 Gunter A. Fischer,14 Lianming The fundamental proposition is that tropical zones We review their content and use your feedback to keep the quality high. A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features Press Copyright Contact us Creators . 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. This hypothesis posits that the size of a biome has considerable influence on its species diversity. Latitudinal gradients in abiotic factors strongly determine species distributions. The existing hypotheses explaining this phenomenon are summarized and the evidence that tends to favor one of these is presented. 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 . 1. In opposition to the latitudinal gradient hypothesis, both the diversity and prevalence of Leucocytozoon parasites decreased towards the equator. 73 interactions hypothesis, then evolutionary rates for sympatric sister pairs (relative to 74 baseline rates for allopatric sister pairs) should be faster in the tropics than the temperate 75 zone. I re-analyze a previously published latitudinal gradient dataset and show that species number is a linear function of the predicted area and that species number is more fully explained by predicted area than by a quadratic function of latitude. This "latitudinal gradient" is Earth's most prevalent biogeographic pattern, but biologists do not agree about its cause. Introduction. Who are the experts? Similarly to the climate harshness hypothesis, climate stability is suggested to be the reason for the latitudinal diversity gradient. Latitudinal gradients in functional, phenetic, and phylogenetic biodiversity are strong, but are not wholly a product of variation in species richness. This trend in species richness (which we will refer to as diversity) Some of the . Here we address whether biotic interactions are more important at low latitudes, finding support for this hypothesis from a wide range of interactions. In fact, if the LH hypothesis is indeed important, there should be a general latitudinal gradient in herbivory at the community level, regardless of the differences in species composition. The geographic area hypothesis advances area as the primary cause of latitudinal gradients in diversity. We review the theoretical arguments suggesting a positive relationship between niche breadth and latitude. foundation species across a latitudinal gradient in china xiujuan qiao, 1,2 jiaxin zhang,1,2,3 zhong wang,4 yaozhan xu,1,2 tianyang zhou,1,2,3 xiangcheng mi,5 min cao, 6 wanhui ye,7 guangze jin,8 zhanqing hao,9 xugao wang,10 xihuawang,11 songyan tian,12 xiankun li, 13 wusheng xiang,13 yankun liu,14 yingnan shao,12 kun xu,15 weiguo sang,5,16 fuping zeng, 17 haibao ren,5 mingxi jiang,1,2 and . 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. Host relatedness and traits known to promote vector exposure neither predicted infection probability nor parasite diversity. Abstract: We examine Robert MacArthur's hypothesis that niche breadth is positively associated with latitude (the latitude-niche breadth hypothesis). Latitudinal gradients in species diversity: the search for the primary cause. Latitudinal gradients in species diversity: the search for the primary cause Klaus Rohde Rohde, K. 1992. discuss latitudinal gradients and mechanistic hypothesis that govern the biological diversity and results in increase in species richness, abundance and diversity in insects.
PDF The latitudinal species richness gradient in New World ... Title: Latitudinal Diversity Gradient Hypothesis, the ...
Therefore, the ecological explanations proffered are usually specific to the group in question. The latitudinal gradient in marine bacteria supports the hypothesis that the kinetics of metabolism, setting the pace for life, has strong influence on diversity.
The hypothesis, in contrast to most other hypotheses attempting to explain latitudinal or other gradients in diversity, does not rely on the assumption that different latitudes or habitats generally have different "ceilings" for species numbers, which are higher in the tropics than in cold environments. Seasonality, the latitudinal gradient of diversity, and ... 1. An evaluation of the geographic area hypothesis using the latitudinal gradient in North American tree diversity Paul V.A. title = "The latitudinal gradient in niche breadth: concepts and evidence.", abstract = "We examine Robert MacArthur's hypothesis that niche breadth is positively associated with latitude (the latitude-niche breadth hypothesis). PDF Latitudinal gradients in species diversity PDF Elevational Gradient Resembles Latitudinal Gradient of ... Thoughts about the Latitudinal Diversity Gradient | elena ... Here we review two major hypotheses for the origin of the latitudinal diversity gradient. Keywords:latitudinal diversity gradient; marine bivalves; species^energy hypothesis 1. As only three processes (specia- 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. PDF The Latitudinal Gradient in Niche Breadth: Concepts and ... Of these factors, temperature is arguably the most important, as its effects are pervasive across all levels of biological organization, from biochemistry of molecular processes to physiology of the whole organism [1-3].As such, it is expected that organisms adapt to latitudinal gradients by . Hypothesis Our interpretation of the main focus; Pianka 1966: 1. What causes latitudinal gradient? - AskingLot.com The predation hypothesis: Ecology 5. 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. 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. A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. 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. The hypothesis is most associated with Rosenzweig (1992, 1995), although its genesis derives from Terborgh (1973). The analysis of recently diverged, hyper-38 rich invertebrate groups provides an opportunity to investigate latitudinal patterns with the hypothesis of species richness along latitude and altitude gradients. Above: Japonica lutea is a butterfly species widely distributed in Japan.
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