The Importance of Ecological Redundancy for Ecosystems Restoration

Restoration ecology is a multidisciplinary science that exchanges several concepts with other scientific fields to improve its practices. In this article, I discuss the ecological redundancy concept and its implications and applications on ecological restoration. Ecological redundancy was coined in the early 1990s to characterize those species that play similar (equivalent) functions in the ecosystem. The concept made it possible to segregate species into functional groups that operate in maintaining the system. I searched the literature and found that although some restoration models naturally consider this concept, studies in areas undergoing restoration which directly measure and test the ecological redundancy are still rare (n = 14). I provide evidence that distinguishing redundant species and identifying key species is feasible for ecological restoration. Additionally, I suggest that redundancy should also be part of the restoration monitoring, for example, by checking if functional groups have been recovered. Theory predicts that if ecological redundancy is correctly incorporated in restoration, projects with more chances of success will be created because redundancy tends to increase ecosystem resilience. Resilience is a crucial factor for restoration sustainability in a changing environment.

Ecophylogenetics Reveals the Evolutionary Associations between Mammals and their Gut Microbiota

A tantalizing hypothesis posits that mammals coevolved with their gut microbiota. Unfortunately, the limited resolution of microbial taxonomy hinders the exploration of this hypothesis and specifically challenges the discovery of gut microbes that are linked to mammalian evolution. To address this, we developed a novel approach that groups microbes into new, more meaningful taxonomic units based on their common ancestry and ecological redundancy. Treating mammalian lineages as different ecosystems, we quantified the distribution of these microbial taxa across mammals. Our analysis discovered monophyletic clades of gut bacteria that are unexpectedly prevalent, or conserved, across all mammals, as well as conserved clades that are exclusive to particular mammalian lineages. These clades often manifest phylogenetic patterns indicating that they are subject to selection. Lineage - specific changes in clade conservation, including a human-accelerated loss of conserved clades, suggest that mammalian evolution associates with a change in the selective regimes that act on gut microbiota. Collectively, these results point to the existence of microbes that possess traits that facilitate their dispersion or survival in the mammalian gut, possibly because they are subject to host selection. Ultimately, our analysis clarifies the relationship between the diversification of the gut microbiome and mammalian evolutionary history.

Ecological singularity of temperate mesopredatory myliobatoid rays (Chondrichthyes: Myliobatiformes)

Many myliobatoid rays are important mesopredators, having significant effects on coastal benthic communities. In tropical and subtropical high-diversity oligotrophic ecosystems, they partition their trophic resources, which results in high ecological singularity. However, it is unknown whether this is true for temperate low-diversity eutrophic ecosystems. In the present study, we tested, for the first time, the hypothesis that myliobatoid mesopredators are ecologically redundant in a temperate low-diversity eutrophic ecosystem. We quantified diet and measured intra- and interspecific trophic overlap in the three species that regularly occur off Uruguay and northern Argentina, namely Myliobatis goodei, Myliobatis ridens and Dasyatis hypostigma. M. ridens had a typical durophagic diet composed of bivalves and gastropods, M. goodei fed primarily on polychaetes and decapods, diverging from the durophagic diet typical of its genus, and D. hypostigma preyed primarily on amphipods and decapods. There were ontogenetic and seasonal dietary differences in all three species. It is concluded that ecological singularity is present in this temperate myliobatoid assemblage, with each species having a different trophic niche. The practice of pooling together myliobatoid mesopredators in trophic models must be abandoned unless there is evidence of ecological redundancy.

Relationships between taxonomic and functional diversity: insights into assembly processes

Among the potential indicators of biodiversity, those based on the functional traits of species are interesting because they measure the aspects of diversity that potentially affect community assembly and function. However, trait-based approaches are still rarely considered and little is known about the degree to which taxonomic diversity (TD) and functional diversity (FD) are correlated. Yet, this relationship is thought to depend on the extent of ecological redundancy within the assemblage, i.e. the number of taxonomically distinct species that exhibit similar ecological functions. In this study, we characterized taxonomic and functional diversity within and between two marine habitats (rocky shore vs mudflats) under human-induced disturbances. Models were also used to test whether the relationship between TD and FD differed according to the indices used to characterize them. We found little effect of human disturbance on the shape of the TD-FD relationship, whereas communities of the mudflat appeared to be less redundant than those of rocky shore. This could be explained by the assembly rules of ecosystems: biotic filtering (competition and resource partitioning) reduces redundancy by selecting for functionally dissimilar species, whereas abiotic filtering increases redundancy by selecting for similar species sharing adaptations to a particular environment. The rocky shore environment is characterized by heterogeneity that allows the formation of distinct ecological niches that can be colonized by similar species: the abiotic filtering does not limit the redundancy permitted by habitat. Conversely, in the more homogeneous environment of mudflat, the biotic filter mitigates redundancy. Trait-mediated abiotic filtering appears to play an important role in community assembly in complex habitats, whereas the relative importance of competitive exclusion appears to be greater in homogeneous habitats.

Relationships between taxonomic and functional diversity: insights into assembly processes

Among the potential indicators of biodiversity, those based on the functional traits of species are interesting because they measure the aspects of diversity that potentially affect community assembly and function. However, trait-based approaches are still rarely considered and little is known about the degree to which taxonomic diversity (TD) and functional diversity (FD) are correlated. Yet, this relationship is thought to depend on the extent of ecological redundancy within the assemblage, i.e. the number of taxonomically distinct species that exhibit similar ecological functions. In this study, we characterized taxonomic and functional diversity within and between two marine habitats (rocky shore vs mudflats) under human-induced disturbances. Models were also used to test whether the relationship between TD and FD differed according to the indices used to characterize them. We found little effect of human disturbance on the shape of the TD-FD relationship, whereas communities of the mudflat appeared to be less redundant than those of rocky shore. This could be explained by the assembly rules of ecosystems: biotic filtering (competition and resource partitioning) reduces redundancy by selecting for functionally dissimilar species, whereas abiotic filtering increases redundancy by selecting for similar species sharing adaptations to a particular environment. The rocky shore environment is characterized by heterogeneity that allows the formation of distinct ecological niches that can be colonized by similar species: the abiotic filtering does not limit the redundancy permitted by habitat. Conversely, in the more homogeneous environment of mudflat, the biotic filter mitigates redundancy. Trait-mediated abiotic filtering appears to play an important role in community assembly in complex habitats, whereas the relative importance of competitive exclusion appears to be greater in homogeneous habitats.