The biogeochemical boomerang: Site fidelity creates nutritional hotspots that may promote recurrent calving site reuse.

Animals interact with nutrient cycles by consuming and depositing nutrients, interactions studied separately in nutritional ecology and zoogeochemistry. Recent theoretical work bridges these disciplines, highlighting that animal-driven nutrient recycling could be crucial in helping animals meet their nutritional needs. When animals exhibit site fidelity, they consistently deposit nutrients, potentially improving vegetation quality. We investigated this potential feedback by analysing changes in forage nitrogen stocks following simulated caribou calving. We found that forage nitrogen stocks increased after 2 weeks and remained elevated after 1 year, a change due to increased forage quality, not quantity. We also developed a nutrient budget within calving grounds, demonstrating that natal fluid and calf carcasses contribute substantial nitrogen subsidies. We, thus, highlight a positive zoogeochemical feedback whereby nutrients deposited during calving become bioavailable during lactation and provide evidence that site fidelity creates a biogeochemical boomerang in which animals deposit nutrients that can be reused later.

Assembly, Persistence, and Disassembly Dynamics of Quaternary Caribbean Frugivore Communities.

AbstractHow communities assemble and restructure is of critical importance to ecological theory, evolutionary theory, and conservation, but long-term perspectives on the patterns and processes of community assembly are rarely integrated into traditional community ecology, and the utility of communities as an ecological concept has been repeatedly questioned in part because of a lack of temporal perspective. Through a synthesis of paleontological and neontological data, I reconstruct Caribbean frugivore communities over the Quaternary (2.58 million years ago to present). Numerous Caribbean frugivore lineages arise during periods coincident with the global origins of plant-frugivore mutualisms. The persistence of many of these lineages into the Quaternary is indicative of long-term community stability, but an analysis of Quaternary extinctions reveals a nonrandom loss of large-bodied mammalian and reptilian frugivores. Anthropogenic impacts, including human niche construction, underlie the recent reorganization of frugivore communities, setting the stage for continued declines and evolutionary responses in plants that have lost mutualistic partners. These impacts also support ongoing and future introductions of invader complexes: introduced plants and frugivores that further exacerbate native biodiversity loss by interacting more strongly with one another than with native plants or frugivores. This work illustrates the importance of paleontological data and perspectives in conceptualizing ecological communities, which are dynamic and important entities.

Vertically inherited microbiota and environment modifying behaviours conceal genetic variation in dung beetle life history.

Diverse organisms actively manipulate their (sym)biotic and physical environment in ways that feed back on their own development. However, the degree to which these processes affect microevolution remains poorly understood. The gazelle dung beetle both physically modifies its ontogenetic environment and structures its biotic interactions through vertical symbiont transmission. By experimentally eliminating (i) physical environmental modifications and (ii) the vertical inheritance of microbes, we assess how environment modifying behaviour and microbiome transmission shape heritable variation and evolutionary potential. We found that depriving larvae of symbionts and environment modifying behaviours increased additive genetic variance and heritability for development time but not body size. This suggests that larvae's ability to manipulate their environment has the potential to modify heritable variation and to facilitate the accumulation of cryptic genetic variation. This cryptic variation may become released and selectable when organisms encounter environments that are less amenable to organismal manipulation or restructuring. Our findings also suggest that intact microbiomes, which are commonly thought to increase genetic variation of their hosts, may instead reduce and conceal heritable variation. More broadly, our findings highlight that the ability of organisms to actively manipulate their environment may affect the potential of populations to evolve when encountering novel, stressful conditions.

Can plants build their niche through modulation of soil microbial activities linked with nitrogen cycling? A test with Arabidopsis thaliana.

In natural systems, different plant species have been shown to modulate specific nitrogen (N) cycling processes so as to meet their N demand, thereby potentially influencing their own niche. This phenomenon might go beyond plant interactions with symbiotic microorganisms and affect the much less explored plant interactions with free-living microorganisms involved in soil N cycling, such as nitrifiers and denitrifiers. Here, we investigated variability in the modulation of soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively), and their ratio (NEA : DEA), across 193 Arabidopsis thaliana accessions. We studied the genetic and environmental determinants of such plant-soil interactions, and effects on plant biomass production in the next generation. We found that NEA, DEA, and NEA : DEA varied c. 30-, 15- and 60-fold, respectively, among A. thaliana genotypes and were related to genes linked with stress response, flowering, and nitrate nutrition, as well as to soil parameters at the geographic origin of the analysed genotypes. Moreover, plant-mediated N cycling activities correlated with the aboveground biomass of next-generation plants in home vs away nonautoclaved soil, suggesting a transgenerational impact of soil biotic conditioning on plant performance. Altogether, these findings suggest that nutrient-based plant niche construction may be much more widespread than previously thought.

The self-in-the-world map emerged in the primate brain as a basis for Homo sapiens abilities.

The brain in the genus Homo expanded rapidly during evolution, accelerated by a reciprocated interaction between neural, cognitive, and ecological niches (triadic niche construction, or TNC). This biologically costly expansion incubated latent cognitive capabilities that, with a quick and inexpensive rewiring of brain areas in a second phase of TNC, provided the basis for Homo sapiens specific abilities. The neural demands for perception of the human body in interaction with tools and the environment required highly integrated sensorimotor domains, inducing the parietal lobe expansion seen in humans. These newly expanded brain areas allowed connecting the sensations felt in the body to the actions in the world through the cognitive function of "projection". In this opinion article, we suggest that as a relationship of equivalence between body parts, tools and their external effects was established, mental mechanisms of self-objectification might have emerged as described previously, grounding notions of spatial organization, idealized objects, and their transformations, as well as socio-emotional states in the sensing agent through a self-in-the-world map. Therefore, human intelligence and its features such as symbolic thought, language, mentalizing, and complex technical and social behaviors could have stemmed from the explicit awareness of the causal relationship between the self and intentional modifications to the environment.

Individualized social niches in animals: Theoretical clarifications and processes of niche change.

What are social niches, and how do they arise and change? Our first goal in the present article is to clarify the concept of an individualized social niche and to distinguish it from related concepts, such as a social environment and a social role. We argue that focal individuals are integral parts of individualized social niches and that social interactions with conspecifics are further core elements of social niches. Our second goal in the present article is to characterize three types of processes-social niche construction, conformance, and choice (social NC3 processes)-that explain how individualized social niches originate and change. Our approach brings together studies of behavior, ecology, and evolution and integrates social niches into the broader concept of an individualized ecological niche. We show how clarifying the concept of a social niche and recognizing the differences between the three social NC3 processes enhance and stimulate empirical research.

Human behaviors driving disease emergence.

Interactions between humans, animals, and the environment facilitate zoonotic spillover-the transmission of pathogens from animals to humans. Narratives that cast modern humans as exogenous and disruptive forces that encroach upon "natural" disease systems limit our understanding of human drivers of disease. This review leverages theory from evolutionary anthropology that situates humans as functional components of disease ecologies, to argue that human adaptive strategies to resource acquisition shape predictable patterns of high-risk human-animal interactions, (2) humans construct ecological processes that facilitate spillover, and (3) contemporary patterns of epidemiological risk are emergent properties of interactions between human foraging ecology and niche construction. In turn, disease ecology serves as an important vehicle to link what some cast as opposing bodies of theory in human ecology. Disease control measures should consider human drivers of disease as rational, adaptive, and dynamic and capitalize on our capacity to influence ecological processes to mitigate risk.

Bridging the explanatory gaps: What can we learn from a biological agency perspective?

We begin this article by delineating the explanatory gaps left by prevailing gene-focused approaches in our understanding of phenotype determination, inheritance, and the origin of novel traits. We aim not to diminish the value of these approaches but to highlight where their implementation, despite best efforts, has encountered persistent limitations. We then discuss how each of these explanatory gaps can be addressed by expanding research foci to take into account biological agency-the capacity of living systems at various levels to participate in their own development, maintenance, and function by regulating their structures and activities in response to conditions they encounter. Here we aim to define formally what agency and agents are and-just as importantly-what they are not, emphasizing that agency is an empirical property connoting neither intention nor consciousness. Lastly, we discuss how incorporating agency helps to bridge explanatory gaps left by conventional approaches, highlight scientific fields in which implicit agency approaches are already proving valuable, and assess the opportunities and challenges of more systematically incorporating biological agency into research programs.

Building behavior does not drive rates of phenotypic evolution in spiders.

Do animals set the course for the evolution of their lineage when manipulating their environment? This heavily disputed question is empirically unexplored but critical to interpret phenotypic diversity. Here, we tested whether the macroevolutionary rates of body morphology correlate with the use of built artifacts in a megadiverse clade comprising builders and nonbuilders-spiders. By separating the inferred building-dependent rates from background effects, we found that variation in the evolution of morphology is poorly explained by artifact use. Thus natural selection acting directly on body morphology rather than indirectly via construction behavior is the dominant driver of phenotypic diversity.

Egg-laying by female Aedes aegypti shapes the bacterial communities of breeding sites.

BACKGROUND: Aedes aegypti, the main arboviral mosquito vector, is attracted to human dwellings and makes use of human-generated breeding sites. Past research has shown that bacterial communities associated with such sites undergo compositional shifts as larvae develop and that exposure to different bacteria during larval stages can have an impact on mosquito development and life-history traits. Based on these facts, we hypothesized that female Ae. aegypti shape the bacteria communities of breeding sites during oviposition as a form of niche construction to favor offspring fitness. RESULTS: To test this hypothesis, we first verified that gravid females can act as mechanical vectors of bacteria. We then elaborated an experimental scheme to test the impact of oviposition on breeding site microbiota. Five different groups of experimental breeding sites were set up with a sterile aqueous solution of larval food, and subsequently exposed to (1) the environment alone, (2) surface-sterilized eggs, (3) unsterilized eggs, (4) a non-egg laying female, or (5) oviposition by a gravid female. The microbiota of these differently treated sites was assessed by amplicon-oriented DNA sequencing once the larvae from the sites with eggs had completed development and formed pupae. Microbial ecology analyses revealed significant differences between the five treatments in terms of diversity. In particular, between-treatment shifts in abundance profiles were detected, showing that females induce a significant decrease in microbial alpha diversity through oviposition. In addition, indicator species analysis pinpointed bacterial taxa with significant predicting values and fidelity coefficients for the samples in which single females laid eggs. Furthermore, we provide evidence regarding how one of these indicator taxa, Elizabethkingia, exerts a positive effect on the development and fitness of mosquito larvae. CONCLUSIONS: Ovipositing females impact the composition of the microbial community associated with a breeding site, promoting certain bacterial taxa over those prevailing in the environment. Among these bacteria, we found known mosquito symbionts and showed that they can improve offspring fitness if present in the water where eggs are laid. We deem this oviposition-mediated bacterial community shaping as a form of niche construction initiated by the gravid female.