Speciation as an active force in promoting genetic evolution

There is a growing appreciation among evolutionary biologists that the rate and tempo of molecular evolution might often be altered at or near the time of speciation, i.e. that speciation is in some way a special time for genes. Molecular phylogenies frequently reveal increased rates of genetic evolution associated with speciation and other lines of investigation suggest that various types of abrupt genomic disruption can play an important role in promoting speciation via reproductive isolation. These phenomena are in conflict with the gradual view of molecular evolution that is implicit in much of our thinking about speciation and in the tools of modern biology. This raises the prospect of studying the molecular evolutionary consequences of speciation per se and studying the footprint of speciation as an active force in promoting genetic divergence. Here we discuss the reasons to believe that speciation can play such a role and elaborate on possible mechanisms for accelerated rates of evolution following speciation. We provide an example of how it is possible detect whether accelerated bursts of evolution occur in neutral and/or adaptive regions of genes and discuss the implications of rapid episodes of change for conventional models of molecular evolution. Speciation might often owe more to ephemeral and essentially arbitrary events that cause reproductive isolation than to the gradual and regular tug of natural selection that draws a species into a new niche.

Rooting theories of plant community ecology in microbial interactions

Predominant frameworks for understanding plant ecology have an aboveground bias that neglects soil micro-organisms. This is inconsistent with recent work illustrating the importance of soil microbes in terrestrial ecology. Microbial effects have been incorporated into plant community dynamics using ideas of niche modification and plant–soil community feedbacks. Here, we expand and integrate qualitative conceptual models of plant niche and feedback to explore implications of microbial interactions for understanding plant community ecology. At the same time we review the empirical evidence for these processes. We also consider common mycorrhizal networks, and propose that these are best interpreted within the feedback framework. Finally, we apply our integrated model of niche and feedback to understanding plant coexistence, monodominance and invasion ecology.

Bridging the gaps between agricultural policy, land-use and biodiversity

The fate of biodiversity is intimately linked to agricultural development. Policy reform is an important driver of changes in agricultural land-use, but there is considerable spatial variation in response to policy and its potential impact on biodiversity. We review the links between policy, land-use and biodiversity and advocate a more integrated approach. Ecologists need to recognize that wildlife-friendly farming is not the only land-use strategy that can be used to conserve biodiversity and to research alternative options such as land sparing. There is also a need for social scientists and ecologists to bring their approaches together, so that land-use change and its consequences can be investigated in a more holistic way.

Adaptation and speciation: what can F-st tell us?

A useful way of summarizing genetic variability among different populations is through estimates of the inbreeding coefficient, F-st. Several recent studies have tried to use the distribution of estimates of F-st from individual genetic loci to detect the effects of natural selection. However, the promise of this approach has yet to be fully realized owing to the pervasive dogma that this distribution is highly dependent on demographic history. Here, I review recent theoretical results that indicate that the distribution of estimates of F-st is generally expected to be robust to the vagaries of demographic history. I suggest that analyses based on it provide a useful first step for identifying candidate genes that might be under selection, and explore the ways in which this information can be used in ecological and evolutionary studies.

Limpets break Dollo's law

A new molecular phylogeny of the limpet molluscs (Calyptraeidae) reveals that coiled shells have independently re-evolved at least once in this family, which is a violation of Dollo's Law that complex ancestral states, once lost, are never reacquired. Reacquisition of the coiled ancestral state is remarkable in that uncoiled shells have been the most recent ancestral state for 20 million-100 million years. Adult coiling might have reevolved by the mechanism of prolonging the period during which genes for coiling are expressed in larvae. This and other developmental mechanisms could provide general routes for maintaining the potential to produce traits lost in distant ancestors.

Orphan worms and, homeless parasites enhance bilaterian diversity

Microscopic endoparasites belonging to the Phylum Myxozoa provide a striking example of how much there is still to be learned about the diversity of the Metazoa. Recent research on myxozoans has provided new insights into evolution within the Bilateria, revealing unparalleled levels of morphological simplification associated with parasitism, a home for an orphan worm, and a hypothesis of the endosymbiotic origin(s) for extrusible intracellular organelles in myxozoans and cnidarians. In addition, discovery of the source of a devastating disease of salmonid fish has enabled researchers to identify two ancient clades within the Myxozoa, and has exposed new mysteries concerning myxozoan life-cycle evolution and evolutionary diversification. This plethora of new insights exemplifies the fundamental value of studying obscure organisms.

Global pollinator declines: trends, impacts and drivers

Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect themaintenance of wild plant diversity, wider ecosystemstability, crop production, food security and human welfare.

Ecological intensification: harnessing ecosystem services for food security

Rising demands for agricultural products will increase pressure to further intensify crop production, while negative environmental impacts have to be minimized. Ecological intensification entails the environmentally friendly replacement of anthropogenic inputs and/or enhancement of crop productivity, by including regulating and supporting ecosystem services management in agricultural practices. Effective ecological intensification requires an understanding of the relations between land use at different scales and the community composition of ecosystem service-providing organisms above and below ground, and the flow, stability, contribution to yield, and management costs of the multiple services delivered by these organisms. Research efforts and investments are particularly needed to reduce existing yield gaps by integrating context-appropriate bundles of ecosystem services into crop production systems.

Combined effects of global change pressures on animal-mediated pollination

Pollination is an essential process in the sexual reproduction of seed plants and a key ecosystem service to human welfare. Animal pollinators decline as a consequence of five major global change pressures: climate change, landscape alteration, agricultural intensification, non-native species, and spread of pathogens. These pressures, which differ in their biotic or abiotic nature and their spatiotemporal scales, can interact in nonadditive ways (synergistically or antagonistically), but are rarely considered together in studies of pollinator and/or pollination decline. Management actions aimed at buffering the impacts of a particular pressure could thereby prove ineffective if another pressure is present. Here, we focus on empirical evidence of the combined effects of global change pressures on pollination, highlighting gaps in current knowledge and future research needs.

Biodiversity, cultural pathways, and human health: a framework

Direct contact with biodiversity is culturally important in a range of contexts. Many people even join conservation organisations to protect biodiversity that they will never encounter first-hand. Despite this, we have little idea how biodiversity affects people's well-being and health through these cultural pathways. Human health is sensitive to apparently trivial psychological stimuli, negatively affected by the risk of environmental degradation, and positively affected by contact with natural spaces. This suggests that well-being and health should be affected by biodiversity change, but few studies have begun to explore these relationships. Here, we develop a framework for linking biodiversity change with human cultural values, well-being, and health. We argue that better understanding these relations might be profoundly important for biodiversity conservation and public health.

Biodiversity and resilience of ecosystem functions

Accelerating rates of environmental change and the continued loss of global biodiversity threaten functions and services delivered by ecosystems. Much ecosystem monitoring and management is focused on the provision of ecosystem functions and services under current environmental conditions, yet this could lead to inappropriate management guidance and undervaluation of the importance of biodiversity. The maintenance of ecosystem functions and services under substantial predicted future environmental change (i.e., their ‘resilience’) is crucial. Here we identify a range of mechanisms underpinning the resilience of ecosystem functions across three ecological scales. Although potentially less important in the short term, biodiversity, encompassing variation from within species to across landscapes, may be crucial for the longer-term resilience of ecosystem functions and the services that they underpin.

Human evolution, nutritional ecology and prebiotics in ancient diet

Modern studies of prebiotic non digestible carbohydrates continue to expand and demonstrate their colonic and systemic benefits. However, virtually nothing is known of their use among ancient populations. In this paper we discuss evidence for prebiotic use in the archaeological record from select areas of the world. It is suggested that members of our genus Homo would have had sufficient ecological opportunity to include prebiotic-bearing plants in diet as early as ~ 2 million years ago, but that significant dietary intake would not have taken place until the advent of technological advances that characterized the Upper Paleolithic of ~40,000 years ago. Throughout human evolution, hominid populations that diversified their diet to include prebiotic-bearing plants would have had a selective advantage over competitors.

Sperm competition and the evolution of testes size in terrestrial mammalian carnivores

Summary Understanding the factors influencing variation in the degree of sperm competition is a key question underlying the mechanisms driving sexual conflict. Previous behavioural and comparative studies have indicated that carnivores appear to have evolved under sperm competition but an analysis of the predictors of the level of sperm competition is missing. In this study, we use phylogenetic comparative methods to investigate life-history parameters predicted to affect the degree of sperm competition in terrestrial carnivores using variation in relative testes size (RTS, after controlling for body size allometry) as a measure of the level of sperm competition. Due to a paucity of consistent data across taxa, we used three measures of RTS: testes mass (n = 40 species), testes and epididymes mass combined (n = 38), and testes volume (n = 48). We also created a derived data set (n = 79) with testes mass estimated from regression analyses on the other measures of testes size. Carnivores with shorter mating seasons had relatively larger testes, consistent with the hypothesis that sperm competition is greater when the degree of female oestrous synchrony is high. This relationship was stronger in spontaneous versus induced ovulators, suggesting higher sperm competition levels in spontaneous ovulators. This is the first comparative study to show this within mammalian taxa. Neither social mating system nor reproductive lifespan were significantly associated with variation in RTS and hence are poor predictors of sperm competition levels. None of the above relationships were found to be significant for the testes and epididymes mass combined data set, but our understanding of the role of the epididymis in sperm competition is too limited to draw any conclusions. Finally, we consistently found a significant phylogenetic signal in all analyses, indicating that phylogeny has played a significant role in the evolution of carnivore testes size and, therefore, in shaping levels of sperm competition. Our results shed new light into the factors affecting levels of sperm competition in terrestrial carnivores by showing that the degree of oestrous synchrony and ovulation type interact to predict variation in RTS.