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The numerous explanations for why Earth's biodiversity is concentrated at low latitudes fail to explain variation in the strength and even direction of the gradient through deep time. Consequently, we do not know if today's gradient is representative of what might be expected on other planets or is merely an idiosyncrasy of Earth's history. We propose a hierarchy of factors driving the latitudinal distribution of diversity: (i) over geologically long time spans, diversity is largely predicted by climate; (ii) when climatic gradients are shallow, diversity tracks habitat area; and (iii) historical contingencies linked to niche conservatism have geologically short-term, transient influence at most. Thus, latitudinal diversity gradients, although variable in strength and direction, are largely predictable on our planet and possibly others. Myriad hypotheses try to explain the current latitudinal diversity gradient (LDG), with biodiversity concentrated in the tropics during a colder climate today than has been present for most of the history of complex life. When Earth was hotter, however, LDGs were often flat or temperate-peaked. Variation in the strength and direction of LDGs through deep time can be explained by the direct effects of climate, with habitat area becoming important when climatic gradients are shallow; less predictable factors such as organismal evolution to past climatic conditions – tropical conservatism – have short-term, transient influence at most. Enhanced collaboration between ecologists and paleobiologists, bringing together data from both fields, is critical to better understand fundamental processes on our planet and possibly others. [ABSTRACT FROM AUTHOR]

Effective conservation strategies must ensure that species remain not just extant, but able to maintain key roles in species interactions and in the maintenance of communities and ecosystems. Such ecological functions, however, have not been well incorporated into management or policy. We present a framework for quantifying ecological function that is complementary to population viability analysis (PVA) and that allows function to be integrated into strategic planning processes. Ecological function analysis (EFA) focuses on preventing secondary extinctions and maintaining ecosystem structure, biogeochemical processes, and resiliency. EFA can use a range of modeling approaches and, because most species interactions are relatively weak, EFA needs to be performed for relatively few species or functions, making it a realistic way to improve conservation management. Highlights Most current conservation strategies focus on preventing extinctions, but without explicit regard for the maintenance of sufficient abundance so that species can continue to interact with other species or impact the structure and function of their ecosystems. We develop the concepts and tools for ecological function analysis (EFA), to measure and quantify the roles that species play. EFA focuses on preventing cascading extinctions as well as maintaining ecosystem resiliency and critical biogeochemical processes. Because relatively few species have such strong ecosystem roles, EFA needs to be considered for manageable numbers of species and functions. EFA is flexible and adaptive, making it a critical complement to species-based approaches in improving conservation management. [ABSTRACT FROM AUTHOR]

Extinctions beget further extinctions when species lose obligate mutualists, predators, prey, or hosts. Here, we develop a conceptual model of species and community attributes affecting secondary extinction likelihood, incorporating mechanisms that buffer organisms against partner loss. Specialized interactors, including ‘cryptic specialists’ with diverse but nonredundant partner assemblages, incur elevated risk. Risk is also higher for species that cannot either evolve new traits following partner loss or obtain novel partners in communities reorganizing under changing environmental conditions. Partner loss occurs alongside other anthropogenic impacts; multiple stressors can circumvent ecological buffers, enhancing secondary extinction risk. Stressors can also offset each other, reducing secondary extinction risk, a hitherto unappreciated phenomenon. This synthesis suggests improved conservation planning tactics and critical directions for research on secondary extinctions. [ABSTRACT FROM AUTHOR]

Abstract: When humans reduce top carnivore abundance in insular systems, herbivore populations may increase, with cascading impacts on the community. But the prevalence of such “trophic release” effects in non-insular ecosystems remains little known, particularly in tropical ecosystems. We assessed whether areas with low top carnivore abundance were associated with greater abundance of herbivores across seven rainforest study areas in Malaysian Borneo. We deployed 134 camera-trap stations and analyzed the resulting photographic detections from 16,608 trap-days using multi-species occupancy models that estimate abundance while accounting for imperfect detectability. Estimated local abundance of Sunda clouded leopards (Neofelis diardi), the apex mammalian predator, varied from 0.0 to 3.5 individuals per camera location. Clouded leopard abundance was not negatively correlated with the abundance of any of the four prey species that we analyzed. Rather, sites with few or no clouded leopards also had the lowest estimated abundance of pig-tailed macaques (Macaca nemestrina). Estimated abundance of muntjac (Muntiacus spp.) and mousedeer (Tragulus spp.) was statistically unrelated to estimated clouded leopard abundance. Bearded pig (Sus barbatus) abundance was likewise unaffected by predator abundance, but pigs appear to live in larger groups when clouded leopards are common, possibly to better defend their young. We found no evidence of trophic release, an important conservation threat in other areas, in this ecosystem, particularly relative to the massive impacts of agricultural conversion, habitat degradation, and unsustainable wildlife exploitation. [Copyright &y& Elsevier]

Unsustainable hunting does more than threaten wildlife populations and human livelihood – Carlos Peres and colleagues recently showed that it can also reduce how much carbon the forest stores. Maintaining primates and other important seed dispersing animals in tropical forests could be an important piece of the climate change mitigation puzzle. [ABSTRACT FROM AUTHOR]

Abstract: A growing understanding of the ecology of seed dispersal has so far had little influence on conservation practice, while the needs of conservation practice have had little influence on seed dispersal research. Yet seed dispersal interacts decisively with the major drivers of biodiversity change in the 21st century: habitat fragmentation, overharvesting, biological invasions, and climate change. We synthesize current knowledge of the effects these drivers have on seed dispersal to identify research gaps and to show how this information can be used to improve conservation management. The drivers, either individually, or in combination, have changed the quantity, species composition, and spatial pattern of dispersed seeds in the majority of ecosystems worldwide, with inevitable consequences for species survival in a rapidly changing world. The natural history of seed dispersal is now well-understood in a range of landscapes worldwide. Only a few generalizations that have emerged are directly applicable to conservation management, however, because they are frequently confounded by site-specific and species-specific variation. Potentially synergistic interactions between disturbances are likely to exacerbate the negative impacts, but these are rarely investigated. We recommend that the conservation status of functionally unique dispersers be revised and that the conservation target for key seed dispersers should be a population size that maintains their ecological function, rather than merely the minimum viable population. Based on our analysis of conservation needs, seed dispersal research should be carried out at larger spatial scales in heterogenous landscapes, examining the simultaneous impacts of multiple drivers on community-wide seed dispersal networks. [Copyright &y& Elsevier]