Species–area relationship - Wikipedia
The species-area relationship is one of the oldest known and most documented patterns in ecology. It describes the general pattern of increase. Introduction: The relationship between island area and number of species is well diversity patterns have important implications for conservation of biodiversity. for Biodiversity and Conservation, University of Leeds, Leeds LS2 9JT, UK. Summary. 1. The species–area relationship (SAR) has long been used to describe.
More recently, ecologists have attempted to infer ecological process from the form and parameters of these models.
The impact of habitat heterogeneity and increased risk of extinction in small areas have been explored most often, but other key ecological processes e. In addition, several studies have examined how aspects of sampling design, such as whether observations are nested or scattered across space or are of regular or irregular shapes and sizes, influence the shape and parameters of the species-area relationship through their different sensitivities to species aggregation, habitat heterogeneity, and biogeographic processes.
Furthermore, species-area relationships are often quantified differently, depending on the goals of a study. Despite the fact that most studies of species-area relationships focus on inferring ecological phenomena from the form of the relationship, small-scale trends often reflect spatial processes that limit the number of individuals that can fit in a small area.
In summary, the mathematical functions used to characterize species-area relationships often have different parameters when applied to data from different ranges of area, and these differences in observed species-area functions are often attributed to sampling methodologies and underlying ecological and biogeographical processes.
Looking forward, ecological research is expanding from its past species-centric perspective to a greatly increased focus on traits of organisms and their phylogenetic relationships, which is leading to examination of how these factors also vary with area see Beyond Species-Area Relationships.
Species-Area Relationships - Ecology - Oxford Bibliographies
General Overviews Species-area relationships were first documented and debated among plant ecologists seeking to characterize and compare plant communities.
The subject later gained popularity among animal ecologists with the seminal work of Preston on species abundance distributions and with Robert MacArthur and Edward O. An excellent historical review is provided in McGuinnesswhich connects debates over the form and function of species-area relationships with emerging ecological theory.
Connor and McCoy also reviews the evidence linking species-area relationships to biological and ecological explanations, but the authors focus on the statistical validity of attempts to use the form and parameters of species-area curves to discern ecological causality. Rosenzweig explores in detail several examples of species-area curves and uses them to discuss the many factors that influence the shape of these curves, while Drakare, et al.
Because of the variety of research goals inherent in studies of species-area relationships, sampling and analytical methods, as well as definitions of what constitutes a species-area relationship, often vary among studies. Scheiner defines six types of species-area curves that differ in the spatial arrangement of samples, whether larger samples are constructed in a spatially explicit fashion from adjacent smaller samples, and whether means or single values are used for a given spatial scale.
The statistics and biology of the species-area relationship. Which function describes the species-area relationship best?
The constants C and z are fitted from the data on island area and number of species, and so are specific to a data set. Browne and Peck used long-horned beetles Cerambycidae: Coleoptera to investigate the species-area relationship in the Florida Keys and mainland. Their data are plotted below, using the log10 of the area and species number.
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The two data points furthest to the right represent, from left to right, South Florida the area south of Lake Okeechobee and the entire state of Florida. All other data points are from the Keys. We can also plot the log10 of species number against the log10 of the distance of the islands from the Florida mainland.
The relationship between the log10 of the species number and the log10 of island area clearly shows an increasing trend, and is well-approximated by the linear form of the model. Similarly, a decreasing trend of species number with island distance can be seen from the second graph. Whether or not the number of species is at equilibrium is less clear; interpretation of the data regarding this question is made more difficult by uncertainty about the history of sea-level changes over the past 10, years.
Both island size and distance from the mainland are associated with the number of species present. In general, it has been found that the relationship between island area and number of species present is fairly constant for islands in a given geographic region.