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"animal communities"
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Animal groups
\"Lions and bees and meerkats, oh my--these are a few of the many animals that survive and thrive in groups. Discover how group members help each other face life's challenges. From finding food to raising young, some animals are just better off together\"--Back cover.
Book
Animal vigilance : monitoring predators and competitors
Animal Vigilance builds on the author's previous publication with Academic Press (Social Predation: How Group Living Benefits Predators and Prey) by developing several other themes including the development and mechanisms underlying vigilance, as well as developing more fully the evolution and function of vigilance.Animal vigilance has been.
eBook
Animals and African ethics
\"African ethics is primarily concerned with community and harmonious communal relationships. The claim is frequently made on behalf of African moral beliefs and customs that African society does not objectify and exploit nature and natural existents, unlike Western moral attitudes and practices. This book investigates whether this claim is correct by examining religious and philosophical thought, as well as traditional cultural practices in Africa. Through exploration of what kind of status is reserved for other-than-human animals in African ethics, Horsthemke argues that moral perceptions and attitudes on the African continent remain resolutely anthropocentric, or human-centred. Although values like ubuntu (humanness) and ukama (relationality) have been expanded to include nonhuman nature, animals have no rights, and human duties to them are almost exclusively 'indirect'. Animals and African Ethics concludes by asking whether those who, following their own liberation, continue to exploit and oppress other creatures, are not thereby contributing to their own dehumanization. \"-- Provided by publisher.
Book
Relative role of deterministic and stochastic determinants of soil animal community: a spatially explicit analysis of oribatid mites
1. Ecologists are debating the relative role of deterministic and stochastic determinants of community structure. Although the high diversity and strong spatial structure of soil animal assemblages could provide ecologists with an ideal ecological scenario, surprisingly little information is available on these assemblages. 2. We studied species-rich soil oribatid mite assemblages from a Mediterranean beech forest and a grassland. We applied multivariate regression approaches and analysed spatial autocorrelation at multiple spatial scales using Moran's eigenvectors. Results were used to partition community variance in terms of the amount of variation uniquely accounted for by environmental correlates (e.g. organic matter) and geographical position. Estimated neutral diversity and immigration parameters were also applied to a soil animal group for the first time to simulate patterns of community dissimilarity expected under neutrality, thereby testing neutral predictions. 3. After accounting for spatial autocorrelation, the correlation between community structure and key environmental parameters disappeared: about 40% of community variation consisted of spatial patterns independent of measured environmental variables such as organic matter. Environmentally independent spatial patterns encompassed the entire range of scales accounted for by the sampling design (from tens of cm to 100 m). This spatial variation could be due to either unmeasured but spatially structured variables or stochastic drift mediated by dispersal. Observed levels of community dissimilarity were significantly different from those predicted by neutral models. 4. Oribatid mite assemblages are dominated by processes involving both deterministic and stochastic components and operating at multiple scales. Spatial patterns independent of the measured environmental variables are a prominent feature of the targeted assemblages, but patterns of community dissimilarity do not match neutral predictions. This suggests that either niche-mediated competition or environmental filtering or both are contributing to the core structure of the community. This study indicates new lines of investigation for understanding the mechanisms that determine the signature of the deterministic component of animal community assembly.
Journal Article
Decoupling the effects of logging and hunting on an Afrotropical animal community
In tropical forests, hunting nearly always accompanies logging. The entangled nature of these disturbances complicates our ability to resolve applied questions, such as whether secondary and degraded forest can sustain populations of tropical animals. With the expansion of logging in central Africa, conservation depends on knowledge of the individual and combined impacts of logging and hunting on animal populations. Our goals were (1) to decouple the effects of selective logging and hunting on densities of animal guilds, including apes, duikers, monkeys, elephant, pigs, squirrels, and large frugivorous and insectivorous birds and (2) to compare the relative importance of these disturbances to the effects of local-scale variation in forest structure and fruit abundance. In northern Republic of Congo, we surveyed animals along 30 transects positioned in forest disturbed by logging and hunting, logging alone, and neither logging nor hunting. While sampling transects twice per month for two years, we observed 47 179 animals of 19 species and eight guilds in 1154 passages (2861 km). Species densities varied by as much as 480%% among forest areas perturbed by logging and/or hunting, demonstrating the strong effects of these disturbances on populations of some species. Densities of animal guilds varied more strongly with disturbance type than with variation in forest structure, canopy cover, and fruit abundance. Independently, logging and hunting decreased density of some guilds and increased density of others: densities varied from 44%% lower (pigs) to 90%% higher (insectivorous birds) between logged and unlogged forest and from 61%% lower (apes) to 77%% higher (frugivorous birds) between hunted and unhunted forest. Their combined impacts exacerbated decreases in populations of some guilds (ape, duiker, monkey, and pig), but counteracted one another for others (squirrels, insectivorous and frugivorous birds). Together, logging and hunting shifted the relative abundance of the animal community away from large mammals toward squirrels and birds. Logged forest, even in the absence of hunting, does not maintain similar densities as unlogged forest for most animal guilds. To balance conservation with the need for economic development and wild meat in tropical countries, landscapes should be spatially managed to include protected areas, community hunting zones, and production forest.
Journal Article
Top-down and bottom-up consequences of unchecked ungulate browsing on plant and animal diversity in temperate forests: lessons from a deer introduction
Debate on the relative importance of competition for resources and trophic interactions in shaping the biological diversity of living communities remains unsettled after almost a century. Recently, dramatic increases in ungulate populations have provided a useful quasi-experiment on the effects of unrestrained ungulates on forest ecology. The islands of Haida Gwaii (Canada) offer a unique situation to investigate the potential of large herbivores to control temperate forest community structure and diversity. Black-tailed deer Odocoileus hemionus Merriam, native to adjacent mainland areas of British Columbia, were introduced in 1878 and spread to all but a few islands. Because deer were not native to the archipelago, islands that still lack deer provide a rare instance of temperate forest vegetation and fauna that developed in the absence of large herbivores. The colonisation of different islands at different times, and the absence of significant predation allow us to assess whether and how a large herbivore can exert “top-down” control on vegetation and its associated fauna. We studied plant communities in forest interior and shoreline, on seven small islands of varying browse history. Three islands were untouched by deer, deer had been resident for about 15 years on two, and on another two deer had been present for more than 50 years. Without deer, vegetation in the understorey and/or shrub layer was dense or very dense. Structure and composition varied markedly within and between shoreline and interior communities. Without deer, shoreline communities were dominated by species absent from islands with deer. Where deer had been present for less than 20 years most plant species characteristic of shorelines on islands without deer were already absent or scarce, but in the forest interior species richness was less affected and extensive shrub thickets remained. On islands where deer had been present for >50 years vegetation below the browse line was extremely simplified, converging in both forest interior and shoreline towards an open assemblage of a few deer-tolerant species, basically two coniferous trees. This top down effect on the plant community reflected up the food chain so that understorey invertebrate and shrub-dependent songbird communities became simplified. In contrast, species densities of litter arthropods (especially weevils and millipedes) were highest where deer were present for >50 years. Canopy birds were unaffected by deer presence. In the absence of predators, major climatic stress or other means to control the herbivore, deer browsing created greatly simplified plant and animal communities.
Journal Article
Interpreting the replacement and richness difference components of beta diversity
AIM: The variation in species composition among sites, or beta diversity, can be decomposed into replacement and richness difference. A debate is ongoing in the literature concerning the best ways of computing and interpreting these indices. This paper first reviews the historical development of the formulae for decomposing dissimilarities into replacement, richness difference and nestedness indices. These formulae are presented for species presence–absence and abundance using a unified algebraic framework. The indices decomposing beta play different roles in ecological analysis than do beta‐diversity indices. INNOVATION: Replacement and richness difference indices can be interpreted and related to ecosystem processes. The pairwise index values can be summed across all pairs of sites; these sums form a valid decomposition of total beta diversity into total replacement and total richness difference components. Different communities and study areas can be compared: some may be dominated by replacement, others by richness/abundance difference processes. Within a region, differences among sites measured by these indices can then be analysed and interpreted using explanatory variables or experimental factors. The paper also shows that local contributions of replacement and richness difference to total beta diversity can be computed and mapped. A case study is presented involving fish communities along a river. MAIN CONCLUSIONS: The different forms of indices are based upon the same functional numerators. These indices are complementary; they can help researchers understand different aspects of ecosystem functioning. The methods of analysis used in this paper apply to any of the indices recently proposed. Further work, based on ecological theory and numerical simulations, is required to clarify the precise meaning and domain of application of the different forms. The forms available for presence–absence and quantitative data are both useful because these different data types allow researchers to answer different types of ecological or biogeographic questions.
Journal Article
Differential post-dispersal seed predation drives chaparral seed bank dynamics
Animal community structure influences plant community structure in many ways, one of which is varying post-dispersal seed predation rates by different, sometimes distantly related animal taxa. In fire-prone mediterranean-climate vegetation, such as California chaparral, rodents are commonly assumed to be the most effective post-dispersal seed predators, which would render them the main driver for soil seed bank dynamics. This is a critical issue because the most dominant species of the chaparral rely on dormant, persistent soil seed banks to recruit after wildfires. Here, we used a series of exclusion experiments in combination with close video observation to show that granivorous birds are more effective than rodents in removing seeds of Ceanothus papillosus, a fire-dependent obligate seeder shrub of the California chaparral. We furthermore used seed traps and germination experiments to show that C. papillosus can have extremely high seed production and expresses strong intra and inter-annual seed bank dynamics. We conclude in contrast to other studies, that granivorous birds, in addition to rodents, are major determinants of C. papillosus seed bank densities. We also found that seed bank density increased between years, despite high seed predation rates. We conclude that high seed production in combination with small and dark seed design may help some seeds to stay undetected, thus allowing C. papillosus to build a sufficiently dense enough seed bank to regenerate after wildfire. Our results indicate that the ratio of granivorous birds to rodents has the potential to play a major role in shaping chaparral community structure by differentially impacting soil seed bank densities.
Journal Article
Effects of dispersal and environmental heterogeneity on the replacement and nestedness components of β-diversity
Traditionally metacommunity studies have quantified the relative importance of dispersal and environmental processes on observed β-diversity. Separating β-diversity into its replacement and nestedness components and linking such patterns to metacommunity drivers can provide richer insights into biodiversity organization across spatial scales. It is often very difficult to measure actual dispersal rates in the field and to define the boundaries of natural metacommunities. To overcome those limitations, we revisited an experimental metacommunity dataset to test the independent and interacting effects of environmental heterogeneity and dispersal on each component of β-diversity. We show that the balance between the replacement and nestedness components of β-diversity resulting from eutrophication changes completely depending on dispersal rates. Nutrient enrichment negatively affected local Zooplankton diversity and generated a pattern of β-diversity derived from nestedness in unconnected, environmentally heterogeneous landscapes. Increasing dispersal erased the pattern of nestedness, whereas the replacement component gained importance. In environmentally homogeneous metacommunities, dispersal limitation created community dissimilarity via species replacement whereas the nestedness component remained low and unchanged across dispersal levels. Our study provides novel insights into how environmental heterogeneity and dispersal interact and shape metacommunity structure.
Journal Article
What Are Species Pools and When Are They Important?
A regional species pool comprises all species available to colonize a focal site. The roots of the concept are imbedded in island biogeography theory, supply-side ecology, and early propagule addition experiments. The pool concept allows ecologists to examine large-scale effects-including geographic area, evolutionary age, and immigration and diversification-on the diversity, composition, and phylogenetic structure of local communities. Both theory and evidence show that pool influences are greatest when local communities are not strongly and predictably structured by species interactions (e.g., under frequent disturbance or if many species are rare). Practical and conceptual issues to consider when delineating species pools include choosing an appropriate spatial scale, whether to account for environmental filtering, whether to include the species within a fixed geographic area versus those whose geographic ranges overlap with a site, or whether to use databases or geographic data sources. Each issue is discussed in the context of 63 studies using the species pool approach. We conclude that the species pool concept has contributed greatly to our understanding of community dynamics by bridging the gap between large and small spatial scales. Future studies must compare pool characteristics with community structure across multiple regions for a more complete understanding of community assembly.
Journal Article