Attempts to explain this lbg have tended to ignore a deeptime perspective. Comparing latitudinal and upstreamdownstream gradients. Latitudinal patterns of species richness in hardbottom. Recent reports that find latitudinal diversity gradients to be reduced or absent in some unicellular organisms and attribute this to their high abundance and. The latitudinal species richness gradient in new world. 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 gradient of increasing species richness with decreasing latitude is one of the most wellestablished patterns in macroecology. An impediment to understanding the origin and dynamics of the latitudinal diversity gradient ldgthe most pervasive large scale biotic pattern on earthhas been the tendency to focus narrowly on a single causal factor when a more synthetic, integrative approach is needed. Turnover in space and time seem to exhibit similar scale dependency along latitudinal gradients.
A distinct latitudinal gradient of diatom diversity is. Gradients of biodiversity university of connecticut. In fungi, conversely, the inverted latitudinal diversity gradient tedersoo et al. It is one of the most venerable, welldocumented, and controversial large scale patterns in macroecology willig et al. The strong correlation between species richness and climate is frequently interpreted as reflecting a causal link via processes linked to energy or evolutionary rates. The belowground soil prokaryotic community plays a cardinal role in sustaining the stability and functions of forest ecosystems. Pdf latitudinal gradients in phylogenetic relatedness of. Broad scale patterns in species diversity and species range size are the primary components of research within this focal area. Here, i discuss recent findings in spatial and temporal turnover along abiotic and biotic gradients at two different extents. This project aims to analyse information on invertebrate biodiversity patterns of the offshore benthos around south africa. Use of demersal bycatch data to determine the distribution. Gaston 2000 18, discussing not just latitudinal gradients but global patterns in biodiversity in general, writes that no single mechanism adequately explains all examples of a given pattern, that the patterns.
A relatively small number of broad scale patterns describe the distribution of biodiversity across the earth. Willig mr, kaufman dm, stevens rd 2003 latitudinal gradients of biodiversity. Here, we report marine synechococcus diversity in the surface. One of the primary interests in repeatedly examining large. Pdf explaining latitudinal patterns in species diversity tom. The gradient is pervasive in time and space, and pertains to all major taxa. Historically, research has focused on gradients of species richness i. The latitudinal gradient in species richness is such that most extant eukaryote, perhaps also prokaryote, species are found in the tropics. The presentday decrease in biological diversity from equatorial to polar regions figure 1 is a pervasive pattern governing the distribution of life on earth 1,2.
The latitudinal gradient in species richness is such that most extant eukaryote, perhaps also prokaryote. All of them explore biodiversity focusing on a mono or bidimensional space. Using a data set consisting of 400,000 records covering 3,000 pyrenean species, it is shown that sampling and scale effects alone can give rise to many conflicting speciesrichness patterns. I tested these predictions to better understand the formation of one of the most ubiquitous patterns of biodiversity the latitudinal gradient in species richness. Declines in both redundant and trace species characterize. The ldg is one of the most widely recognized patterns in ecology. This highlights an issue that has been central to much of the debate about the cause of this and other global patterns in biodiversity, namely the assumption that where a pattern. Biologists have long searched for mechanisms responsible for the increase in species richness with decreasing latitude. The edg states that species richness tends to increase as elevation increases, up to a certain point, creating a diversity bulge at middle elevations. The presentday decrease in biological diversity from equatorial to polar regions figure 1 is a pervasive pattern governing the distribution of life on earth 1, 2.
Hemispheric asymmetries in biodiversitya serious matter. Latitudinal gradients of biodiversity the department of ecology. Amongst the earliest remarked, and best documented, of broad scale spatial patterns of life on earth is a trend for more species to be found towards lower latitudes. Pdf the latitudinal biodiversity gradient through deep time. Latitudinal gradients in species diversity wikimili, the. Spatiotemporal climate change contributes to latitudinal. This latitudinal gradient is earths most prevalent biogeographic pattern, but biologists do not agree about its cause. Latitudinal diversity gradients, however, differ for aboveground and belowground species 4, 5, 6 and, therefore, the number of species interacting aboveground and belowground will change with global position. Even when counted over quite small areas in which it is present, the. Although latitudinal variation of synechococcus assemblage in marine surface waters has been observed, few studies compared synechococcus assemblage composition in surface and subsurface waters at the basin scale. Understanding the mechanisms underlying the latitudinal biodiversity gradient may be one of the most important challenges for biologists.
Abstract the latitudinal gradient of decreasing richness from tropical to extratropical areas is ecologys longest recognized pattern. The diversity of living things generally peaks in the tropics and declines toward the poles. Latitudinal gradients of biodiversity are biogeographic patterns that define the ways in. The latitudinal biodiversity gradient through deep time. Exploring the relationship between canopy height and. Latitudinal and vertical variation of synechococcus. The ubiquity of latitudinal gradients in species diversity has led to a search for biological mechanisms that have universal applicability i. Latitudinal gradients in phylogenetic relatedness of angiosperm trees in north america. Some of the most frequently proposed mechanisms include.
We conclude with a forwardlooking synthesis and list of fertile areas for. Phylogenetic diversity by c region and d latitudinal band, where the gray area reflects the distribution of 95% null values while the blue area reflects 95% of observed values across 100 trees in the posterior distribution. The latitudinal gradient of species diversity is a nearly universal pattern brown 1995 and latitude has been said to have the boldest signature with respect to the spatial distribution of biodiversity lewin 1989, gaston 1996. Coupling of soil prokaryotic diversity and plant diversity. The latitudinal biodiversity gradient through deep time ubc zoology. Latitudinal and altitudinal patterns of soil nematode. Consequently, patterns can be evaluated at a variety of scale, ranging from. Pdf patterns and determinants of species richness in.
Scale effects and human impact on the elevational species. On a global scale, climatic conditions constrain aboveground and belowground biodiversity. Some of the most frequently proposed mechanisms include geographic area, net productivity, species. Latitudinal gradients in species diversity pdf file. Through the integration of latitudinal and altitudinal gradients, our results show that latitudinal patterns of soil nematode community structure are mainly quadratic low nematode abundance at midlatitude, whereas altitudinal patterns are mainly linear low nematode abundance at. Macroecology and macroevolution of the latitudinal.
However, rarely considered is how a cline in species richness may be reflected in. Conversely, the volume of the forests is rarely considered. Latitudinal gradient an overview sciencedirect topics. The latitudinal diversity gradient ldg, where the number of species increases from the poles to the equator, ranks among the broadest and most notable biodiversity patterns on earth. The understanding of spatial variation in biological traits, including abundance and life history traits from the intra. 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. Latitudinal gradients in species richness are ecologys longest and most studied pattern. Species turnover along abiotic and biotic gradients. Synechococcus is one of the most widely distributed and abundant picocyanobacteria in the global oceans. Put another way, in the present day localities at lower latitudes generally have more species than localities at higher latitudes. The geographic area hypothesis advances area as the primary cause of latitudinal gradients in. For two centuries, biologists have documented a gradient of animal and plant biodiversity from the tropics to the poles but have been unable to agree whether it is controlled primarily by productivity, temperature, or historical factors.
Geographical gradients in argentinean terrestrial mammal. Thus, differences among studies in the form or parameterization of the latitudinal gradient could be a consequence of inherent differences among them with respect to characteristics of scale i. Latitudinal variation in nematode diversity and ecological. Microbes do not follow the elevational diversity patterns. My work has increasingly emphasized the scale dependence of both pattern and process. Latitudinal gradients in species diversity klaus rohde. Results indicate wellsupported predictions for new world leafnosed bats and that diversification has had strong influences on latitudinal gradients of species richness. Main conclusions the results of this study support two of the major predictions. The latitudinal gradient of decreasing richness from tropical to extratropical areas is ecologys longest recognized pattern. The increase in species richness or biodiversity that occurs from the poles to the tropics, often referred to as the latitudinal diversity gradient ldg, is one of the most widely recognized patterns in ecology. In the present work, we tested a global correlation between vascular plant species richness s and average forest canopy height h, the. 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. 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. Linking aboveground and belowground diversity sciencedirect.
Yet, the nature of how soil prokaryotic diversity covaries with aboveground plant diversity along a latitudinal gradient remains elusive. Elevational diversity gradient edg is an ecological pattern where biodiversity changes with elevation. The latitudinal diversity gradient is a wellknown biogeographic pattern. Here, we redress this balance by bringing together data on the past distribution of biodiversity and examine what this reveals about the underlying.
Latitudinal gradients in species diversity wikipedia. This more conventional spatial pattern is conveniently known as the latitudinal diversity gradient because of the strong covariance of richness and other measures of biodiversity that it describes. Dozens of mechanisms have been proposed to explain the pattern of increasing species richness toward low latitudes gaston, 2000. As a consequence, i have been involved with the development of theory as well as with its empirical. Historical processes enhance patterns of diversity along. Abstract the latitudinal gradient of decreasing richness from tropical to. This gradient is linked unequivocally to corresponding trends in basin and stream properties with impact on resource supply.
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