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This chapter discusses the ecological characteristics of animals as an excellent dispersal agent of plant seeds. Plants are fundamentally sessile with their only chance of dispersal being as seeds. Seeds rely on animals, as well as other abiotic agents such as air and water current for transportation. The chapter also explains the scattering of seeds by terrestrial vertebrate frugivores (endozoochory), seed transportation outside of mammals and birds (epizoochory), invertebrates (myrmecochory), fish (ichthochory), reptiles, and the combination of different forms of dispersal (diplochory) as well as the advantages of animal-based dispersal.

Seed dispersal by frugivorous birds is a globally important ecosystem service. Nearly 4000 bird species have been observed eating fruit and collectively these species likely disperse seeds of at least 68,000 plants. The types of fruits eaten by birds are structurally diverse but fall into three functional groups, multi-seeded berries, few-seeded drupes, and single-seeded arils in dehiscent structures. Birds disperse primarily tree and shrub seeds, but also disperse the seeds of lianas, herbaceous plants, epiphytes, and hemiparasites. Through seed dispersal, birds are important drivers of plant community dynamics and therefore are essential in supporting many of the ecosystem services that those habitats and their constituent species provide. While much research on seed dispersal by birds has focused on the more frugivorous species, most of the bird species that eat fruit do so seasonally or only occasionally and the seed dispersal roles of most of these species are not well understood. Through their sheer numbers, opportunistic, generalist and/or occasional frugivores may be ecologically important in some ecosystems, but their influence has been little studied. Current trends in habitat loss and other human impacts, especially in the tropics, are threatening larger species of frugivores and the large-seeded plants only these birds disperse.

Ducks, shorebirds, rails, gulls and other waterbirds act as vectors of seeds, spores and other plant diaspores carried internally in their guts, externally on their feathers, feet or bills, or used as nesting material. Darwin was the first to understand the significance of dispersal by migratory waterbirds in plant evolution, biogeography and ecology. Countless aquatic and terrestrial plants are dependent on dispersal by waterbirds for long-distance dispersal, and this has probably been the case since the Cretaceous. However, plant ecologists and waterfowl biologists alike have been slow to recognize the importance of this dispersal mode as an ecosystem service. Seed dispersal by waterbirds plays a vital role in plant population dynamics, population genetics and changes in species distributions in response to habitat change and climate warming. On the other hand, waterbirds also spread alien species, and their role as vectors should be taken into account when considering how to prevent and manage biological invasions.

This chapter deals with the ecology of Tropical East Asia from a plant perspective. The life cycle of forest trees is covered in detail, including their vegetative and reproductive phenology, pollination, seed dispersal, seed predation, and the seedling, sapling, and adult stages. Other life forms, including lianas, ground herbs, epiphytes, hemi-epiphytes, and parasites are considered in less detail. Recent advances in plant community ecology are discussed, including the mechanisms responsible for the maintenance of species diversity in tropical forests (niche differentiation, growth–survival trade-offs, conspecific negative density-dependent mortality, neutral theory), and the influence of functional traits and phylogeny on community assembly. Forest succession is discussed in a regional context.

Desert animals and plants interact in ways that have strongly influenced their respective evolutionary trajectories. This chapter begins with herbivory because of its widespread impacts, many of which are presumed to be negative. It then moves on to some other important aspects of desert plant—animal interactions, with a focus on pollination and seed dispersal. Of the various forms of pollination, the chapter will explore the yucca moth-yucca and senita moth-senita cactus mutualisms. With regard to the role of animals in seed predation and seed dispersal, it will consider the effects of small mammals and ants on seed abundance, and the role of large mammals in dispersing the seeds of keystone Acacia species. This selection of examples illustrates how the relatively simple nature of the desert environment has given biologists unique insights into the importance of plant—animal interactions for ecosystem function.

In this chapter, Cagan H. Sekercioglu recapitulates natural ecosystem functions and services. Ecosystem services are the set of ecosystem functions that are useful to humans. These services make the planet inhabitable by supplying and purifying the air we breathe and the water we drink. Water, carbon, nitrogen, phosphorus, and sulfur are the major global biogeochemical cycles. Disruptions of these cycles can lead to floods, droughts, climate change, pollution, acid rain, and many other environmental problems. Soils provide critical ecosystem services, especially for sustaining ecosystems and growing food crops, but soil erosion and degradation are serious problems worldwide. Higher biodiversity usually increases ecosystem efficiency and productivity, stabilizes overall ecosystem functioning, and makes ecosystems more resistant to perturbations. Mobile linked animal species provide critical ecosystem functions and increase ecosystem resilience by connecting habitats and ecosystems through their movements. Their services include pollination, seed dispersal, nutrient deposition, pest control, and scavenging. Thousands of species that are the components of ecosystems harbor unique chemicals and pharmaceuticals that can save people's lives, but traditional knowledge of medicinal plants is disappearing and many potentially valuable species are threatened with extinction. Increasing habitat loss, climate change, settlement of wild areas, and wildlife consumption facilitate the transition of diseases of animals to humans, and other ecosystem alterations are increasing the prevalence of other diseases. Valuation of ecosystem services and tradeoffs helps integrate these services into public decision‐making and can ensure the continuity of ecosystems that provide the services.

Interspecific interactions are based on an entirely selfish cost–benefit system, which depends on the relative gain as compared to loss in fitness produced by the interaction. Antagonistic and mutualistic interactions are related in many ways. Over evolutionary time, certain antagonistic interactions can exhibit a shift in outcome so that the interacting species benefit from the interaction. A change in outcome from antagonism to mutualism is most likely in interactions that are inevitable within the lifetimes of individuals and may have their evolutionary origin in the defense reactions of species. Ants and plants are involved in seed and fruit dispersal as well as pollination. This chapter describes the general characteristics of the reward offered by the plants to the ants (elaiosomes). It offers some general concepts on the selective advantage to plants of seed dispersal by ants that have been associated with a variety of major benefits or hypotheses, followed by examples provided by research done in different regions of the world. The chapter also examines the distribution and significance of myrmecochory worldwide.

Dispersal is a term used for the dissemination of detached reproductive structures from parent plants to a new site. Disseminules include spores, seeds, fruits, whole inflorescences, whole plants, fragments of the parent plant, bulbs and bulbils. Fruit attributes related to a particular dispersal agent or dispersal syndromes are complex and have resulted from millions of years of evolution. In practice, dispersal is mainly local, although some species of sea coasts are well adapted for long-distance dispersal. Knowledge of the modes of plant dispersal is vital to the study of coastal dune ecology because of the clear correlation between diversity and dispersal mechanisms. From the evolutionary point of view, dispersal improves fitness of species: the progeny is able to colonize a new site and extend the range of the species. The fitness here will be defined as getting to a coastal site by using any vector for dispersal, colonization of the new site (germination, establishment and reproduction) and dispersal of the propagules of the immigrant from the new site. Dispersal confers many benefits to the populations of plant species. It reduces competition for limited space and resources in the parental location and the more widely dispersed the propagules, the greater are the chances for the offspring to colonize elsewhere. Dispersal increases the chances of survival and evolution of more fit strains of a species by occupying more diverse habitats than the parents, and speciation may eventually occur in response to new selective pressures. For species adapted to live along sea coasts, dispersal by sea is primarily directed for dissemination to another site by the sea coast. During dispersal several physiological changes may occur in the disseminules that facilitate colonization of the species at the new habitat. For example, Barbour (1972) reported that immersion of upper fruits of Cakile maritima in seawater stimulated their subsequent germination under controlled conditions. Seed coat dormancy may also be broken by abrasion of seeds in sand while being rolled along the sand surface. Considering the large number of species along coasts and on islands, only a very few species may be successfully disseminated in seawater.

This chapter shows that dispersal models only describe some processes deterministically and summarize the effects of the remaining processes in stochastic terms. It discusses the variation in distance and direction of seed dispersal and how it arises from the fact that seeds are dispersed by multiple vectors, that one and the same vector behaves differently under different circumstances, and that some variation in plant and seed traits are relevant for dispersal. Despite this variation, it should be possible in principle to predict almost exactly the dispersal of a given seed. This would, however, require perfect knowledge about how traits and environmental conditions determine dispersal, and about the dynamics and initial conditions of these determinants.

This chapter deals with the ecology of Tropical East Asia from a plant perspective. The life cycle of forest trees is covered in detail, including pollination, seed dispersal, seed predation, and the seedling, sapling, and adult stages. Other life forms, including lianas, ground herbs, epiphytes, and hemi-epiphytes, are considered in less detail. Recent advances in plant community ecology are discussed, including the mechanisms responsible for the maintenance of species diversity in tropical forests (growth–survival trade-offs, negative density dependence, Janzen–Connell effects, neutral theory), and the influence of functional traits and phylogeny on community assembly. Forest succession is discussed in a regional context.

This chapter focuses on changes in animal diversity and composition during forest regeneration and how these changes are linked to interactions between plants and animals. Recovery of animal communities is closely linked to the recovery of plant diversity. Species composition of animal taxa recovers slowly due to the gradual influx of old-growth specialists. Non-flying taxa, rare species, endemic species, and taxa with specialized dietary or nesting requirements are less likely to colonize isolated and small areas of regenerating forests during early stages. Early successional plant species support higher densities of herbivores and sustain greater amounts of herbivory than late successional species. Seed dispersal by frugivores increases during forest regeneration, along with increases in seed size and the proportion of shade-tolerant species. Dispersal limitation and seed predation decrease rates of succession, particularly in isolated pasture sites. Over 90% of the flowering plant species in tropical forests rely on animals for pollination.

This chapter assesses forms of dispersal and describes some indications of potential dispersal limitation on island incidence in Barkley Sound. Ferns appear to be the classic plant taxon in which there are no dispersal limitations. The chapter analyzes fern distribution and the influence of habitat and suitable conditions for persistence, and also discusses various means of seed dispersal, including zoochory (dispersal via fruits or berries by vertebrates); hydrochory (dispersal by sea currents); and anemochory (dispersal by drifting in wind currents).

Frugivory is a hallmark of the Phyllostomidae, and frugivorous species in subfamilies Carolliinae and Stenodermatinae are among the most common mammals throughout the Neotropics. In this chapter we discuss the coevolution of fruits and phyllostomid frugivores; the morphological and other traits that these bats use to detect and process fruit; their foraging behavior and its consequences for seed dispersal; and the network structure of this coevolved mutualism and its conservation implications. Frugivorous phyllostomids have been interacting with fleshy-fruited angiosperms for about 20 Ma and currently disperse the seeds of hundreds of species of plants found throughout angiosperm phylogeny. They are especially important dispersers of early successional plants. Collectively, the feeding and foraging behavior of these bats creates strongly leptokurtic seed dispersal curves, but whose long tails can sometimes lead to the colonization of new habitats. Two foraging guilds (or modules in network parlance) have evolved: an understory guild of carolliines and Sturnira bats and a canopy guild of mostly stenodermatine bats. Ecological redundancy likely exists within these two guilds, but it is threatened whenever bat diversity is reduced by natural or anthropogenic factors. Climate change is one such factor, and its effects warrant careful monitoring.

This chapter discusses the evolutionary histories and geographic distributions of tropical plants and their vertebrate mutualists. It addresses the following questions: how widespread are vertebrate pollination and seed dispersal mutualisms in the phylogenies of angiosperms, birds, and mammals? How many times have these mutualisms evolved independently in these groups? To what extent is the evolution of pollination and seed dispersal mutualisms congruent or noncongruent in these phylogenies? Where have these mutualisms evolved? Are there evolutionary “hotspots” for these mutualisms and are these hotspots congruent for both mutualisms? And what are the temporal patterns of the evolution of these mutualisms and are these patterns congruent for both mutualisms? How long have specific groups of plants and their vertebrate mutualists been interacting?

The ecology of a planet is influenced by historical processes. At any stage in its development, the current conditions of life on a planet form the starting point from which new conditions develop. This means that over time, an ever increasing number of historical accidents will be incorporated into the system and so the role of past history will become increasingly important. This happens across a range of scales, from the chance long distance dispersal of seeds, to the survival of mass extinction events. Gould's interpretation of the Burgess Shale is discussed as a well-known example of the potential importance of historical contingency. The idea of historical contingency is a simple one and yet it is crucially important in understanding much of ecology. This constrained the possible subsequent trajectories of ecological development on Earth.

All who work on dipterocarps will be aware of the almost unique supra-annual reproduction of dipterocarps in the aseasonal tropics, associated with El Niño climatic events. This ‘masting’ reproductive behaviour gives rise to long periods of resource scarcity punctuated by short-lived periods of resource abundance. This is thought to drive many ecological processes in the aseasonal Asian tropics, including those affecting seedling survival, plant distributions, and population genetics. Reproductive patterns are, however, more complex than has been hitherto thought, and there is much yet to learn much about what drives reproductive patterns among dipterocarp species. The evolutionary drivers for masting behaviour among dipterocarps in insular Southeast Asia are described, as are the proximate cues that initiate masting. In the more climatically seasonal region masting gives way to more predictable annual or biannual reproductive phenologies. Pollination processes, which differ in masting and non-masting regions, are described. The chapter continues to describe fruit production and dispersal. The implications of pollination and seed dispersal processes for population genetics are evaluated, as is evidence for hybridization, apomixes, and selfing. Finally, predation of seed can be very substantial among dipterocarps, and has been proposed as a driver of masting behaviour.

Plant–animal interactions are as important in deserts as they are in any other ecosystem. Although it is likely that abiotic factors have greater influence in deserts than in other ecosystems, biotic factors are nonetheless very important. Desert plants and animals interact in ways that have strongly influenced their respective evolutionary trajectories. Interesting forms of these interactions include herbivory, pollination, seed dispersal, and seed predation. There is considerable evidence that many coevolved interactions occur in deserts, some of the most unique being between pollinators and their flowers. As with all mutualisms, there is a cost involved—if either of the species, for any reason, cannot be found at the right place at the right time, each of the species suffers reproductive failure. Regarding seed dispersal and seed predation, myrmecochory (seed dispersal by ants) is often regarded as a diffuse mutualism between a guild of plants and a guild of ants.

Studies on seed dispersal of tropical species have traditionally focused on fruit consumption and seed deposition patterns created by primary seed dispersers. More recently, however, the relevance of postdispersal events for seed fate and demography of plant species has been repeatedly emphasized for a number of dispersal systems. Indeed, recent studies have demonstrated that postdispersal events, some of them involving ants as seed vectors, can markedly affect seed fate in numerous plant species from different regions. Although myrmecochory can be an important dispersal strategy for some plant taxa in neotropical forests, typical myrmecochores are especially common in arid Australia and South Africa, and in Mediterranean and temperate areas. This chapter summarizes recent findings showing that the use of fallen fleshy diaspores by opportunistic ground-dwelling ants can have relevant effects on seed and seedling biology of primarily vertebrate-dispersed plant species. It characterizes the plant and ant species involved in these interactions, addresses the particular attributes of ants and diaspores that mediate the interaction, and discusses the possible consequences of the interaction for the plants.

The anomalously high plant diversity in the Cape has never been satisfactorily explained. However diversification in the Cape is often hypothesized to be linked to specialization on different biotic and abiotic niches. In particular, the biotic community provides an overwhelming number of niches for plants to exploit and specialize on. This chapter asks whether the high plant species diversity in the Cape can be explained by idiosyncrasies in the ways in which plants from the region interact, adapt to, or co-evolve with other organisms. The chapter reviews literature on pollination, seed dispersal, nutrient acquisition by plants (mycorrhizas, parasitic plants, insectivorous plants), and nutrient acquisition of plants (herbivory). In most respects, interactions between Cape plants and other organisms do not appear to be particularly unusual. However, pollination mutualisms do appear to be more specialized in the Cape than in other parts of the world. One end product of specialization onto a diverse array of functionally different pollinators is the presence of particularly well-developed pollination guilds (plants with convergently evolved floral morphologies adapted to the morphology or behaviour of certain pollinator groups). High levels of specialization may be due to the general long-term climatic stability of the region, allowing complex interactions to evolve and allowing time for the speciation process to be completed. Cape plants are also unusually reliant on seed dispersal vectors, e.g. ants which typically disperse seeds over very short distances. This may prevent gene flow from swamping local adaptation, thus allowing divergent selection to translate into diversification.

In antagonistic interactions, the fitness of individuals of one of the interacting species increases, while that of individuals of other interacting species decreases as a result of the interaction. Basically, antagonistic interactions occur between species because living organisms are concentrated packages of energy and nutrients (trophic interactions) and because resources are limited (competition). Antagonistic interactions can be divided into four basic types: parasitism, grazing, predation, and competition. Ants and plants are associated basically in two categories of antagonistic interaction: grazing (leaf-cutting ants) and predation (seed-harvesting ants). Due to the large numbers of seeds removed by ants and the often intense interspecific competition for seeds among ants, granivory and seed harvesting have been considered to be important interactions structuring plant communities. The relationship between antagonism (seed predation) and mutualism (seed dispersal) may be based on the availability of unspecialized seed-collecting ants that contribute to the prevalence of myrmecochory. This chapter reviews leaf-cutter and seed-harvesting ant systems, focusing on the interactions and their effects on the plant community.