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The degree of interdependence and potential for shared coevolutionary history of frugivorous animals and fleshy-fruited plants are contentious topics. Recently, network analyses revealed that mutualistic relationships between fleshy-fruited plants and frugivores are mostly built upon generalized associations. However, little is known about the determinants of network structure, especially from tropical forests where plants' dependence on animal seed dispersal is particularly high. Here, we present an in-depth analysis of specialization and interaction strength in a plant-–frugivore network from a Kenyan rain forest. We recorded fruit removal from 33 plant species in different forest strata (canopy, midstory, understory) and habitats (primary and secondary forest) with a standardized sampling design (3447 interactions in 924 observation hours). We classified the 88 frugivore species into guilds according to dietary specialization (14 obligate, 28 partial, 46 opportunistic frugivores) and forest dependence (50 forest species, 38 visitors). Overall, complementary specialization was similar to that in other plant-–frugivore networks. However, the plant-–frugivore interactions in the canopy stratum were less specialized than in the mid- and understory, whereas primary and secondary forest did not differ. Plant specialization on frugivores decreased with plant height, and obligate and partial frugivores were less specialized than opportunistic frugivores. The overall impact of a frugivore increased with the number of visits and the specialization on specific plants. Moreover, interaction strength of frugivores differed among forest strata. Obligate frugivores foraged in the canopy where fruit resources were abundant, whereas partial and opportunistic frugivores were more common on mid- and understory plants, respectively. We conclude that the vertical stratification of the frugivore community into obligate and opportunistic feeding guilds structures this plant-–frugivore network. The canopy stratum comprises stronger links and generalized associations, whereas the lower strata are composed of weaker links and more specialized interactions. Our results suggest that seed-dispersal relationships of plants in lower forest strata are more prone to disruption than those of canopy trees.

Animals that forage for food via bioturbation can alter their habitat, influencing soil turnover, nutrient cycling and seedling recruitment, effectively acting as ecosystem engineers. Many digging mammals forage for food by digging small pits and creating spoil heaps with the discarded soil. We examined how small‐scale bioturbation, created by the foraging actions of an ecosystem engineer, can alter soil nutrients and subsequently improve growth of plants. We investigated the microbial and chemical properties of soil disturbed by the foraging of an Australian marsupial bandicoot, quenda (Isoodon fusciventer). Soil was collected from the base of 20 recent foraging pits (pit), the associated spoil heaps (spoil) and adjacent undisturbed soil (control) and analysed for nutrients (phosphorus, potassium, sulphur, organic carbon and conductivity) and microbial activity. Soil cores were collected from the same locations and seeds of the dominant canopy species, tuart (Eucalyptus gomphocephala), added to the soil under glasshouse conditions. The growth of seedlings was measured (height, maximum growth, basal stem width, shoot and root biomass) over a 4‐month period and arbuscular mycorrhizae (AM) fungi colonisation rates of seedling roots investigated. Soil from the spoil heaps had the greatest levels of conductivity and potassium. Both the spoil and undisturbed soil had greater amounts of microbial activity and organic carbon. In contrast, the pits had less nutrients and microbial activity. Seedlings grown in spoil soil were taller, heavier, with thicker stems and grew at a faster rate than seedlings in the pit or control soil. Colonisation with AM fungi was greatest for seedlings grown in pit soil. The best predictors of seedling growth were greater amounts of potassium, electrical conductivity and microbial activity. The best predictor of higher colonisation rates of AM fungi was less phosphorus. Bioturbation by ecosystem engineers, like quenda, can alter soil nutrients and microbial activity, facilitating seedling growth. We propose this may be caused by enhanced litter decomposition beneath the discarded spoil heaps. As the majority of Australian digging mammals are threatened, with many suffering substantial population and range contractions, the loss of these species will have long‐term impacts on ecosystem processes. A plain language summary is available for this article. Plain Language Summary

The story of how Africa's mammals have helped shape the continent's landscapes over time to support an amazing diversity of life Africa is home to an amazing array of animals, including the world's most diverse assortment of large mammals. These include the world's largest terrestrial mammal, the African elephant, which still roams great swathes of the continent alongside a host of other well-known large mammals with hooves such as hippopotamuses, giraffes, rhinoceroses, and zebras. African Ark: Mammals, Landscape and the Ecology of a Continent tells the story of where these mammals have come from and how they have interacted to create the richly varied landscape that makes up Africa as we know it today. It gives an equal airing to small mammals, such as rodents and bats, which are often overlooked by both naturalists and zoologists in favor of their larger cousins. African Ark not only describes the diversity of African mammals and the habitats in which they live; it also explains the processes by which species and population groups are formed and how these fluctuate over time. A book on mammals would not be complete without attention placed on the impact of megafauna on the environment and the important roles they play in shaping the landscape. In this way, mammals such as elephants and rhinoceros support countless plant communities and the habitats of many smaller animals. The book brings in a human perspective as well as a conservation angle in its assessment of the interaction of African mammals with the people who live alongside them. African Ark is at once scientifically rigorous and accessible for the layperson and student alike, while drawing on the contributions of numerous zoologists, ecologists and conservationists dedicated to the understanding of Africa and its wildlife.

Large vertebrates affect fire regimes in several ways: by consuming plant matter that would otherwise accumulate as fuel; by controlling and varying the density of vegetation; and by engineering the soil and litter layer. These processes can regulate the frequency, intensity and extent of fire. The evidence for these effects is strongest in environments with intermediate rainfall, warm temperatures and graminoid-dominated ground vegetation. Probably, extinction of Quaternary megafauna triggered increased biomass burning in many such environments. Recent and continuing declines of large vertebrates are likely to be significant contributors to changes in fire regimes and vegetation that are currently being experienced in many parts of the world. To date, rewilding projects that aim to restore large herbivores have paid little attention to the value of large animals in moderating fire regimes. Rewilding potentially offers a powerful tool for managing the risks of wildfire and its impacts on natural and human values. This article is part of the theme issue ‘Trophic rewilding: consequences for ecosystems under global change’.

1. In order to investigate seed dispersal by animals on a landscape scale, we developed the spatially explicit, individual-based mechanistic model SEED (Simulation of Epi- and Endozoochorous Seed Dispersal). The purpose of the model is to predict patterns and densities of seeds dispersed by animals (especially mammals) within a simulated landscape. 2. The model was parameterized for sheep, cattle and deer as vectors but may be applied to other animals if data for parameterization is available. The model data base currently includes parameter values for about 100 plant species. 3. Seed attachment to and seed detachment from the fur, as well as seed excretion after passage through the gut, are explicitly simulated by drawing randomly from distributions that were determined by standardized experiments. Animal movement is simulated as a correlated random walk, but to increase reality of the model, radio-tracking data of animals can also be used. 4. A sensitivity analysis of SEED was conducted to identify the relative importance of plant and animal traits. The analysis highlighted where the main gaps in our knowledge of seed dispersal processes lie. Even though in our study endozoochorous dispersal had the higher potential for long-distance dispersal compared to epizoochory, there is only scarce knowledge about seed production and especially about the proportion of seeds eaten by an animal, parameters which were shown to be of major importance for dispersal. 5. A comparison of variation in plant and animal traits, respectively, showed that dispersal kernels depend more on changes in the animal vector than on the comparably little variation a particular plant species can exhibit. For this reason, animal movement is, from all the dispersal-relevant parameters, the one for which more exact data is most urgently needed. 6. Synthesis. The newly developed simulation model will help to understand, quantify and predict long-distance seed dispersal by animals. The possibility to incorporate real landscapes and movement data from very different animals makes the model generalizable and possibly applicable to a wide range of scientific and applied questions.

Land use is known to reduce the diversity of species and complexity of biotic interactions. In theory, interaction networks can be used to predict the sensitivity of species against co-extinction, but this has rarely been applied to real ecosystems facing variable land-use impacts. We investigated plant-pollinator networks on 119 grasslands that varied quantitatively in management regime, yielding 25 401 visits by 741 pollinator species on 166 plant species. Species-specific plant and pollinator responses to land use were significantly predicted by the weighted average land-use response of each species' partners. Moreover, more specialized pollinators were more vulnerable than generalists. Both predictions are based on the relative interaction strengths provided by the observed interaction network. Losses in flower and pollinator diversity were linked, and mutual dependence between plants and pollinators accelerates the observed parallel declines in response to land-use intensification. Our findings confirm that ecological networks help to predict natural community responses to disturbance and possible secondary extinctions.

Biodiversity is important for many ecosystem processes. Global declines in pollinator diversity and abundance have been recognized, raising concerns about a pollination crisis of crops and wild plants. However, experimental evidence for effects of pollinator species diversity on plant reproduction is extremely scarce. We established communities with 1-5 bee species to test how seed production of a plant community is determined by bee diversity. Higher bee diversity resulted in higher seed production, but the strongest difference was observed for one compared to more than one bee species. Functional complementarity among bee species had a far higher explanatory power than bee diversity, suggesting that additional bee species only benefit pollination when they increase coverage of functional niches. In our experiment, complementarity was driven by differences in flower and temperature preferences. Interspecific interactions among bee species contributed to realized functional complementarity, as bees reduced interspecific overlap by shifting to alternative flowers in the presence of other species. This increased the number of plant species visited by a bee community and demonstrates a new mechanism for a biodiversity-function relationship (\"interactive complementarity\"). In conclusion, our results highlight both the importance of bee functional diversity for the reproduction of plant communities and the need to identify complementarity traits for accurately predicting pollination services by different bee communities.

Fruit traits have historically been interpreted as plant adaptations to their seed dispersers. On the other hand, different environmental factors, which vary spatially and temporally, can shape fruit-trait variation. The mistletoe Tristerix corymbosus has a latitudinal distribution along the South American Pacific rim that encompasses two different biomes, the matorral of central Chile and the temperate forest that extends south of the matorral. This mistletoe shows contrasting fruiting phenology (spring vs summer), fruit color (yellow vs green), and seed dispersers (birds vs marsupial) in these two biomes. We characterized geographic variation of morphological and nutritional fruit traits of T. corymbosus to evaluate which macroecological factor, biome or latitude, better explains spatial variation in these variables. For each of 22 populations, we obtained environmental data (temperature, precipitation, and canopy cover), measured fruit and seed morphology traits (size, shape, and weight), and pulp moisture and nutritional content (fiber, protein, fat, carbohydrates, ash, and caloric content). Patterns of variation for each variable were described by fitting and comparing five different simple models varying in slope, intercept or both. Fruit morphology showed a clear biome-related disruptive pattern, seed morphological traits were unrelated to either biome or latitude, whereas nutritional variables showed diverse patterns. Different environmental factors seem to affect fruit development and phenology, determining the observed fruit characteristics, with seed dispersers playing a minor role in shaping these patterns. More generally, the contrasting plant-seed disperser associations we addressed can be interpreted as the outcome of an ecological-fitting rather than of a coevolutionary process.

Dabbling ducks (Anatinae) are omnivorous birds that are widespread, numerous, highly mobile and often migratory, and therefore have great potential for (long distance) dispersal of other organisms, including plants. However, their ability to act as plant dispersal vectors has received little attention compared to frugivores and is often assumed to be relevant only for wetland species. To evaluate the potential for plant dispersal by dabbling ducks, we collated and analysed existing data. We identified all plant species whose seeds have been recorded in the diets of the seven dabbling duck (Anas) species in the Western Palaearctic, as reported from gut content analyses. We then analysed the habitats and traits of these plant species to identify general patterns, and related these to data on gut passage survival and duck movements. A large number of plant species (> 445 species of 189 genera and 57 families) have been recorded in the diet of dabbling ducks. These plant species represent a very wide range of habitats, including almost the full range of site fertility, moisture and light conditions, excluding only very dry and deeply shaded habitats. The ducks prefer seeds of intermediate sizes (1–10 mm³), which have good chances to survive gut passage, but also ingest smaller and larger seeds. Ingested seeds represent a wide range of dispersal syndromes, including fleshy fruits. Many species (62%) were not previously considered animal‐dispersed in plant data bases, and 66% were not identified as bird‐dispersed. Rarefaction analyses suggest that our analysis still greatly underestimates the total number of plant species ingested. Synthesis. Dabbling ducks do not exclusively ingest seeds of wetland plants, which make up only 40% of the ingested species. Rather, they feed opportunistically on a wide cross‐section of plant species available across the landscapes they inhabit. Given the millions of ducks, the hundreds to thousands of seeds ingested per individual on a daily basis, and known gut passage survival rates, this results in vast numbers of seeds dispersed by ducks per day. Internal seed dispersal by dabbling ducks appears to be a major dispersal pathway for a far broader spectrum of plant species than previously considered.

Fruit traits evolve in response to an evolutionary triad between plants, seed dispersers, and antagonists that consume fruits but do not disperse seeds. The defense trade-off hypothesis predicts that the composition of nutrients and of secondary compounds in fruit pulp is shaped by a trade-off between defense against antagonists and attraction to seed dispersers. The removal rate model of this hypothesis predicts a negative relationship between nutrients and secondary compounds, whereas the toxin-titration model predicts a positive relationship. To test these alternative models, we evaluated whether the contents of nutrients and secondary compounds can be used to predict fruit removal by mutualists and pathogens in 14 bird-dispersed plants on a subtropical island in São Paulo state, southeastern Brazil. We selected eight to ten individuals of each species and prevented fruit removal by covering four branches with a net and left fruits on four other branches available to both, vertebrate fruit consumers and pathogens. The persistence of ripe fruits was drastically different among species for bagged and open fruits, and all fruit species persisted longer when protected against seed dispersers. We found that those fruits that are quickly removed by vertebrates are nutrient-rich, but although the attack rate of pathogens is also high, these fruits have low contents of quantitative defenses such as tannins and phenols. Thus, we suggest that the fruit removal rate by seed dispersers is the primary factor selecting the levels of fruit defense. Likewise, nutrient-poor fruits have low removal of seed dispersers and low probability of attack by pathogens. These species retain ripe fruits in an intact condition for a prolonged period because they are highly defended by secondary compounds, which reduce overall attractiveness. However, this strategy might be advantageous for plants that depend on rare or unreliable dispersers.