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The value of biodiversity is widely appreciated, but we are only beginning to understand the interplay of processes that generate biodiversity and their consequences for coevolutionary interactions. Whereas predator–prey coevolution is most often analyzed in the context of evolutionary arms races, much less has been written about how predators are affected by, and respond to, evolutionary diversification in their prey. We hypothesize here that adaptive radiation of prey may lead to diversification and potentially speciation in predators, a process that we call an upwards adaptive radiation cascade. In this paper we lay out the conceptual basis for upwards adaptive radiation cascades, explore evidence for such cascades, and finally advocate for intensified research. [ABSTRACT FROM AUTHOR]

Abstract: Forging stronger linkages between geomorphology and ecosystem ecology depends, in part, upon developing common conceptualizations of an ecosystem. Because most ecosystem processes are scale dependent, the choice of boundaries is of profound importance to the conceptualization of an ecosystem and to the scope and validity of questions being asked within that ecosystem. Indeed, any conceptualization of an ecosystem requires constraining the spatial and temporal scales of analysis. Thus, it is of particular importance to match the ecosystem boundaries to the question being asked or to the processes being studied and, to facilitate better communication among disciplines, to be explicit in the definitions adopted for an ecosystem. Defining an ecosystem can be problematic when the processes of interest operate at potentially different scales, and little research exists comparing scales of geomorphic processes with those of ecological processes. Here we will discuss the importance of scale in geomorphic and ecological research, and compare and contrast disciplinary biases and inclinations. To highlight the problem of conflicting spatial scales, we will draw on recent attempts to link the structure of food webs to measures of ecosystem size. In particular, problems arise where little or no strong association exists among community membership, resource supply, and physical boundaries. Similar problems arise when trying to link geomorphologic and ecological processes that can operate at different, but variable, temporal scales. [Copyright &y& Elsevier]

Food-chain length is a central characteristic of ecological communities that has attracted considerable attention for over 75 years because it strongly affects community structure, ecosystem processes and contaminant concentrations. Conventional wisdom holds that either resource availability or dynamical stability limit food-chain length; however, new studies and new techniques challenge the conventional wisdom and broaden the discourse on food-chain length. Recent results suggest that resource availability limits food-chain length only in systems with very low resource availability, and call into question the theoretical basis for dynamical stability as a determinant of food-chain length. Evidence currently points towards a complex and contingent framework of interacting constraints that includes the history of community organization, resource availability, the type of predator–prey interactions, disturbance and ecosystem size. Within this framework, the debate has shifted from a search for singular explanations to a search for when and where different constraints operate to determine food-chain length. [Copyright &y& Elsevier]

Highlights: [•] We used live, dead, midden and fossil mollusks to establish an ecological baseline. [•] Ecological change did not increase with pollution toward New York City as expected. [•] Commercial shellfishing had a more significant impact than reduced water quality. [•] Reducing pollution alone may not be an adequate option to restore eutrophied estuaries. [•] Paleoecology studies reveal that ecological baseline information is relevant to restoration. [Copyright &y& Elsevier]

Abstract The Mara River basin is a trans-boundary basin of international importance. It forms the headwaters of the Nile River and serves as the primary dry season water source for an estimated 1.1 million rural people and the largest remaining overland migration of 1.4 million wildebeest in the Serengeti-Mara Ecosystem. Changes throughout the basin are impacting the quantity and quality of the Mara River, yet the historical context of environmental conditions in the basin is not well known. We collected sediment cores throughout the wetland at the mouth of the Mara River, and we used isotopic dating methods and a suite of analyses to examine historical patterns of sediment quantity and source, mercury contamination, and carbon and nutrient loading. Our results show that ecological conditions in the Mara River basin were fairly stable over paleoecological time scales (2000–1000 years before present), but there has been a period of rapid change in the basin over the last 250 years, particularly since the 1960s. A shift in the source and quantity of sediments in the river began in the late 1700s and became much more pronounced in the 1950s and 1960s, coincident with increasing mercury concentrations. The quantity of sediment from the Upper Mara increased, particularly since 1960, but the proportion of total sediment from this region decreased as the Talek and Middle Mara portions of the basin began producing more sediment. The decadal oscillation in sediment accumulation was congruent with known periods of extreme precipitation events. Carbon and nitrogen loading also increased since the 1960s, and the shift in the isotopic ratio of nitrogen provides evidence for increased anthropogenic loading. Altogether, these data likely reflect patterns of change also experienced in other basins throughout East Africa. Graphical abstract Unlabelled Image Highlights • Sediment cores from the Mara River wetland elucidate the basin's historical context. • Most sediment comes from Upper Mara; other catchments have increased since 1960s. • Sediment, mercury and nutrient concentrations started increasing in the 1700s. • Large changes in the 1960s coincident with deforestation and rinderpest eradication • The Mara Wetland is a sink for sediment and mercury coming from upstream. [ABSTRACT FROM AUTHOR]