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Biodiversity in freshwater food webs can be considered in terms of the number of species occupying unique trophic positions or the number of species within a trophic position. Either can affect energy flow or biomass partitioning, and the two aspects of diversity may feed back on one another. This chapter analyses the importance of biodiversity in aquatic food webs on three different levels. First, it asks how varying diversity within trophic groups affects the outcome of trophic interactions. It then presents a conceptual framework and contrasts this model against experimental manipulations of consumer or prey diversity. Second, it asks how consumers and resources affect biodiversity within trophic levels. This question has a long history of experimental and modeling studies, and these are reviewed. The role of biodiversity at local and regional spatial scales for freshwater food webs is examined. Dispersal among local habitats can constrain local species diversity and influence the outcome of food web interactions. The interactive effects of the regional pool versus resident diversity on the outcome of trophic interactions are discussed.

This chapter examines the relationship between species diversity and ecosystem function and stability. This subject is currently one of the most intensely studied topics in ecology. It is also of paramount importance in the study of the ecological consequences of climate change, most probably because of its obvious relevance to ecosystem goods and services. More classically, however, the subject of biodiversity response to climate change relates to what factors set limits to the upper and lower bounds of species diversity and how those factors might be altered by rapid climate change. Of the two processes generating diversity—speciation and immigration—the latter obviously operates at shorter time scales and is likely to respond more immediately to climate change. Of the processes reducing local diversity—extinction and emigration—the latter is, again, likely to operate at shorter time scales, but both processes are likely to be influenced by climate change, although at potentially different timescales.

Ecological communities consist of species that interact to varying degrees within the same geographical area, and so by definition exist within a landscape context. This chapter begins by reviewing the measures and different scales at which species diversity can be assayed, including the use of spatial partitioning to evaluate multiscale patterns of diversity. The chapter then reviews correlates of species diversity, including explanations for latitudinal and elevational diversity gradients, before considering how habitat loss and fragmentation are expected to influence species diversity. The chapter tackles the debate surrounding the relative importance of habitat amount versus fragmentation in predicting species’ responses to landscape change, and highlights the importance of studying these effects at a landscape rather than patch scale. The chapter concludes with a discussion of landscape effects on different types of species interactions, and how interactions among species in different communities can give rise to metacommunity structure and dynamics.

Community ecology and ecosystem ecology provide different perspectives on ecological systems, and have followed increasingly divergent pathways for decades. Recent theoretical and experimental work has begun to integrate these perspectives and provides new light on how species and ecosystems are mutually interdependent. A number of experiments and models have shown that species diversity affects ecosystem functioning through either selection of appropriate dominant species or complementarity among species with different traits. Although particular species may have a large functional impact only at small scales, some hypotheses and experimental evidence suggest that species diversity may also be critical at large temporal and spatial scales. These conclusions, however, have been obtained in relatively simple systems. A major future challenge is to extend this knowledge to full ecosystems with multiple trophic levels and multiple processes, and to determine how biodiversity dynamics, ecosystem processes, and abiotic factors interact.

The chapter focuses on the design and methods of bird survey programmes. It deals with issues such as survey design and selection of study areas, effect of time of day and time of year on counts, how to find and count different kinds of birds, standardizing census efforts in time and space, and problems of bird detectability and survey comparability in different habitats. Mapping or ‘atlas’ methodology, based on grid cells, is also discussed, as well as methods of estimating species richness and diversity, and the storage and accessibility of data. The key points in designing bird surveys are listed. No survey method is perfect; the method chosen should be suited to both purpose and resources, in terms of money, manpower, and skill levels.

Marine conservation priorities have been established mostly on the basis of species and habitat diversity, but little attention has been paid to food web diversity. Ecologists are aware of the dynamic nature of marine food webs, and of the simplification of food web structure by anthropogenic activities, mainly fishing. Transient food web structures along gradients of fishing pressure are an analogue to stages along a successional gradient. This chapter describes regularities in food web structure along these gradients, and explores the global initial conditions (e.g., availability of species, sequence of species additions) needed to ensure that marine food webs will continue to function and adapt to environmental change in a world with increasing anthropogenic disturbance.

This chapter presents a general statistical approach to studying changes in phytoplankton species abundance in relation to climate variability. It then applies this method to an example where changes in phytoplankton species diversity, the dynamics of three phytoplankton species in a Swedish fjord, are related to the North Atlantic Oscillation and other abiotic factors. The chapter concludes with a general outlook underlining the importance of further studies of changes in phytoplankton biovolume.

Given the great differences in productivity between serpentine and nonserpentine habitats, coupled with the heightened presence of endemics and species of conservation concern in the former, it would seem that ecologists interested in studying the factors regulating diversity would gravitate to field and laboratory comparisons across this natural productivity gradient. However, such comparative studies remain rare, even in places where serpentine soils are a common part of the landscape. This chapter reviews ecological studies of disturbance in serpentine vegetation, focusing on general patterns in the responses of plant species diversity to large ungulate herbivory, fire, and soil disturbance.

Endemism is a primary characteristic of the Mediterranean flora. The Mediterranean region contains several zones rich in endemic species. These hotspots of endemism also have a high diversity of total species. The recurrent conjunction of endemism and high species diversity in different parts of the region represents the cornerstone of Mediterranean plant biodiversity. The causes and origins of patterns of diversity and endemism, on both a biogeographic and local scale, are the main subjects of this chapter, which will first invoke the diverse origins of the flora, a premier cause of the patterns we now observe. A major theme this chapter will then develop is the examination of correlated patterns of diversity and endemism in relation to the historical biogeography of islands and mountains that are rich in endemic plants. As the chapter advances it will become more and more apparent that the history of mountain formation is a key element in the high rates of endemic plants both in continental areas and on islands. Finally, the ecological and biological correlates of endemism are treated, in particular the niche in which endemic plants have evolved and persisted.

This chapter uses the species sorting process discussed in Chapter 7 to illuminate several processes of interest to community ecologists. Specifically, it discusses how species composition varies among sites through succession and assembly, and how patterns of diversity respond to important environmental gradients such as disturbance and productivity.

This chapter is a short introduction to the concepts of adaptation to environmental stress, followed by a review of climate change effect son coral reefs, and the environmental factors that cause coral bleaching. The chapter concludes with a discussion of how to prioritize management based on the exposure of reefs to climate change. Climate change is reducing the dominance of calcifying coral species that provide the important reef architecture needed to support fish and fisheries and other ecosystem services, including shoreline protection. Reefs are expected to change towards dominance by either slower growing and stress resistant corals, moderately fast growing calcifying algae, or fast-growing non-calcifying algae, or other groups such as various soft corals, depending on the level of other stress factor. Climate change disturbances are variable in space and time and associated with the spatial heterogeneity suggests that the impacts of climate change will not be simultaneous and uniform and this variability will provide time to implement management and human adaptations that can reduce detrimental consequences for people.

Disturbance alters biodiversity directly by removing species and their functions or by altering their rates of reproduction or mortality. Indirect effects include altering species interactions, modifying the carrying capacity of the habitat, lowering resource abundance and availability, and reducing species vigour. Because each species uses the sum of all resources in its environment in a unique way, alteration of those resources leads to alteration in species diversity. Species diversity can, in turn, alter the characteristics of a disturbance including frequency and severity, resistance, and resilience. Biodiversity is often considered to be positively correlated with the resilience of a community, but this relationship is actually more complex and there is apparently no tight link between biodiversity and resilience. This chapter discusses how disturbance and biodiversity are linked in both space and time, how the addition of invasive species can constitute a disturbance (e.g., through the sudden reduction of native species biomass), and the central role that humans have in altering biodiversity.

Tracing the fieldwork and ideas of Robert H. MacArthur, Howard T. Odum, and Theodosius Dobzhansky, chapter 4 examines the post­World War II rise of efforts to capture the complexity of tropical nature using a simplified quantitative measure: species diversity. The new approaches were abstract but were shaped by U.S. biologists’ experiences in an increasingly wide array of sites within and beyond the circum­Caribbean—facilitated by the U.S. government’s interest in tropical warfare, demand for tropical products, and the growth in air travel. The rise of mathematical and systems approaches in ecology, along with the population perspective of the modern evolutionary synthesis, recast the old question of the biological difference of the tropics. The need for tropical data to solve biology’s core theoretical problems was now unquestionable.

This chapter deals with the geographical distribution of plants and animals within the region. Tropical East Asia is defined as the eastern half of the Oriental Region and the other biogeographical regions are briefly described. The transitions between Tropical East Asia and the adjacent Australian and Palearctic Regions are described and discussed, as well as the less clearly defined transition with the rest of India. Patterns of diversity within Tropical East Asia are considered and four major subregions (Wallacea, the Philippines, Sundaland, and Indochina) are recognized. The remainder of the chapter deals with the biogeography of the numerous islands in the region, including the islands on the Sunda Shelf, Hainan and Taiwan, the Ryukyu and Ogasawara Islands of Japan, the Andaman and Nicobar Islands of India, the Mentawai Islands and others off the west coast of Sumatra, Krakatau, the Philippines, Sulawesi, and the islands of Wallacea.

This chapter initiates a multiyear survey of bats in the reserve and the adjacent Refugio de Vida Silvestre Cueva Los Murciélagos to quantify species diversity, abundances, habitat use, seasonality, and reproduction. It addresses the following questions in surveying bats during five rainy seasons and four dry seasons from July 1999 through February 2006: Which species of bats are present in the area? Are the bat communities the same in three different habitats—coastal/inland forest, and limestone caves? Are the species diversity and abundances of bats in the rainy season similar to those in the dry season? Can seasonal patterns of reproduction be discerned? Are the species diversity and abundances of bats at Cabo Blanco (a tropical moist forest in the Holdridge Life Zone classification) similar to those in the nearly tropical dry forest at Parque Nacional Palo Verde? What are the conservation implications of the bat assemblages found in the regenerating forest?

This chapter takes a look at the energetically based food web processes that can explain the observed relationship between net primary productivity and species diversity. It looks first at independent models of trophic dynamics, and next presents both theory and empirical evidence that the number of consumer species increases as the number of food chains within a community increases. This brings forth the conclusion that species diversity is influenced by both the rate and diversity of production. Through the study of productivity, the energetic efficiencies of consumers, habitat heterogeneity, and the frequency of disturbance, certain hypotheses have been derived to explain patterns in trophic structure and species richness at local, regional, and global scales. The chapter argues, then, that this richness of species is a function of how the rate of production and the diversity of production affect trophic structure, community organization, and patterns of energy utilization in species.

Productivity–diversity relationships have been well studied in some deserts and have helped us to understand the factors controlling ecosystem function at a large spatial scale. Studies of convergence of desert communities and consideration of their similarity with neighbouring mesic communities are some of the best elucidated of this genre. One of the main differences between floras and faunas of the world, particularly in deserts, occurred because of the break-up of Pangaea and the later split between the southern Gondwanan continent and the northern Laurasian continent. Although there is clear derivation of many desert organisms from their mesic adjacent taxa, cases of convergent evolution of desert forms abound, presumably because of the similarities in selection pressures placed on these organisms. There are also some interesting cases of ecological character displacement in deserts that may occur when any two or more species overlap in a crucial aspect of their niches.

Costa Rica’s situation on the Central American Isthmus between the Atlantic and Pacific oceans produces a great deal of species diversity within and between the various ecosystems. This chapter presents a description the main coastal and marine ecosystems of the Pacific coast of Costa Rica, and a discussion of the relationship between these ecosystems and human activity. The first section is a brief history of marine research, followed by an overview of the state of scientific knowledge regarding the coast and descriptions of its physical conditions. The coastal and marine ecosystems are described and the main natural and anthropogenic impacts on those ecosystems are discussed. This information is leveraged to present several conservation initiatives, and propositions for the future in terms of research, management, and conservation, ultimately arguing that protection and conservation of the marine and coastal ecosystems is not only an obligation of the government, but a need and responsibility of everyone.

This chapter examines the phylogeny of the three gastropod clades of Patellogastropoda, Cocculinoidea, and Neritimorpha. It explains that all three taxa are low in species diversity and their placement on the gastropod class, and therefore their relationships to each other and to other gastropod groups remain problematic. It describes the key features of the members of these three clades and highlights the need for further phylogenetic studies.

It is asserted that biodiversity can be understood only when it is set as a collection of continuous social processes. As such, this chapter draws attention to sites that account for cultural habitat, genetic, and species diversity that comprise the world's biodiversity. This chapter calls to mind how complex relationships between seeds, agricultural practices, time, landscapes, farmers, and social communities make up the world's agricultural biodiversity. This chapter attempts to illustrate how both temporal and spatial practices that are exercised by farmers have both resulted and caused various aspects of inter-species and intra-species diversity that are still evident across fields located in various rural populations. The chapter also looks into how certain challenges are posed by the fact that farmers' practices have to adapt to certain changes and networks within the multilateral trading system.