Group: biodiversity_conservation - with tag macroecology [16 articles]

Abstract

Modern climate change is producing poleward range shifts of numerous taxa, communities and ecosystems worldwide. The response of species to changing environments is likely to be determined largely by population responses at range margins. In contrast to the expanding edge, the low-latitude limit (rear edge) of species ranges remains understudied, and the critical importance of rear edge populations as long-term stores of species' genetic diversity and foci of speciation has been little acknowledged. We review recent findings from the fossil record, ...

Abstract

The study of patterns in living diversity is driven by the desire to find the universal rules that underlie the organization of ecosystems. The relative abundance distribution, which characterizes the total number and abundance of species in a community, is arguably the most fundamental measure in ecology. Considerable effort has been expended in striving for a general theory that can explain the form of the distribution. Despite this, a mechanistic understanding of the form in terms of physiological and environmental parameters ...

Abstract

We present an explanation for the widely reported power-law species-area relationship (SAR), which relates the area occupied by a biome to the number of species that it supports. We argue that power-law SARs are a robust consequence of a skewed species abundance distribution resembling a lognormal with higher rarity, together with the observation that individuals of a given species tend to cluster. We show that the precise form of the SAR transcends the specific details of organism interactions, enabling us to ...

Abstract

Neutral and functional theories provide rival interpretations of community patterns involving distribution, abundance, and diversity. One group of patterns describes the overall properties of species or sites, and derives principally from the frequency distribution of abundance among species. According to neutral theory, these patterns are determined by the number of individuals of novel type appearing each generation in the community, whereas functional theory relates them to the distribution of the extent of niches. A second group of patterns describes the spatial ...

Abstract

Large-scale patterns of spatial variation in species geographic range size are central to many fundamental questions in macroecology and conservation biology. However, the global nature of these patterns has remained contentious, since previous studies have been geographically restricted and/or based on small taxonomic groups. Here, using a database on the breeding distributions of birds, we report the first (to our knowledge) global maps of variation in species range sizes for an entire taxonomic class. We show that range area does not ...

Abstract

Patterns of ecotypic variation constitute some of the few `rules' known to modern biology. Here, we examine several well-known ecogeographical rules, especially those pertaining to body size in contemporary, historical and fossil taxa. We review the evidence showing that rules of geographical variation in response to variation in the local environment can also apply to morphological changes through time in response to climate change. These rules hold at various time scales, ranging from contemporary to geological time scales. Patterns of body ...

Abstract

The global decline of coral reefs1, 2 highlights the need to understand the mechanisms that regulate community structure and sustain biodiversity in these systems. The neutral theory, which assumes that individuals are demographically identical regardless of species, seeks to explain ubiquitous features of community structure and biodiversity patterns3, 4, 5. Here we present a test of neutral-theory predictions with the use of an extensive species-level data set of Indo-Pacific coral communities. We show that coral assemblages differ markedly from neutral-model predictions ...

Abstract

This book focuses on rarity, its spatial and temporal dynamics, causes, and interaction with conservation. Although they can be viewed from many different perspectives, rare species are of particular concern to conservationists because they tend to have a greater probability of extinction. This book therefore identifies a number of important issues both heuristic and practical. ...

Abstract

Positive relationships between the local abundance and the range size of the species in a taxonomic assemblage are very general. Explanations for these relationships typically focus on two mechanisms, based on differences in the niche breadths of species, or metapopulation dynamics. Others have, however, also been suggested. Here we identify and clarify all the principal mechanisms proposed to explain positive interspecific abundance-range size relationships. We critically assess the assumptions and predictions that they make, and the evidence in support of them. ...

Abstract

The theory of island biogeography[1] asserts that an island or a local community approaches an equilibrium species richness as a result of the interplay between the immigration of species from the much larger metacommunity source area and local extinction of species on the island (local community). Hubbell[2] generalized this neutral theory to explore the expected steady-state distribution of relative species abundance (RSA) in the local community under restricted immigration. Here we present a theoretical framework for the unified neutral theory of biodiversity[2] and an analytical solution for the distribution ...

Abstract

AimTo attack a widespread myth.LocationWorld-wide.MethodsSimple mathematical logical and empirical examples.ResultsAs both species and area are finite and non-negative, the species–area relationship is limited at both ends. The log species–log area relationship is normally effectively linear on scales from about 1 ha to 107 km2. There are no asymptotes. At the intercontinental scale it may get steeper; at small scales it may in different cases get steeper or shallower or maintain its slope.Main conclusionThe species–area relationship does not have an asymptote. ...

Abstract

This document has been prepared on behalf of the United Nations Environment Programme (UNEP) by the World Conservation Monitoring Centre (WCMC). Its purpose is to provide useful information on inland waters and their biodiversity to a wide audience, ranging from those interested in the state of the world environment generally, to those needing an overview of the global and regional context in order to improve planning, management and investment decisions. This report is explicitly preliminary in approach, largely because of the enormous ...

Abstract

We present the first global map of vascular plant species richness by ecoregion and compare these results with the published literature on global priorities for plant conservation. In so doing, we assess the state of floristic knowledge across ecoregions as described in floras, checklists, and other published documents and pinpoint geographical gaps in our understanding of the global vascular plant flora. Finally, we explore the relationships between plant species richness by ecoregion and our knowledge of the flora, and between plant ...

Abstract

To a first approximation, the distribution of biodiversity across the Earth can be described in terms of a relatively small number of broad-scale spatial patterns. Although these patterns are increasingly well documented, understanding why they exist constitutes one of the most significant intellectual challenges to ecologists and biogeographers. Theory is, however, developing rapidly, improving in its internal consistency, and more readily subjected to empirical challenge. ...