Carbon budget trends in octocorals: a literature review with data reassessment and a conceptual framework to understand their resilience to environmental changes

Although octocorals are a key component of marine hard-bottom systems, their feeding performance is still poorly understood. Understanding carbon budget trends in octocorals’ feeding ecology seems essential to assess their role in benthic–pelagic coupling and to predict their responses to environmental changes. Herein, we provide a review of the feeding ecology of octocorals and an overall data reassessment of their carbon budgets through a systematic and comprehensive search of peer-reviewed literature published between 1960 and 2020, highlighting knowledge gaps. Overall, the feeding ecology of more than 95% of octocoral species remains unknown. Based on the available data, suspension feeding accounts for 162.8 ± 171.0% of the metabolic requirements in azooxanthellate octocorals and 28.7 ± 32.3% in zooxanthellate octocorals. Autotrophy is responsible for 156.7 ± 113.9% of the acquired carbon in zooxanthellate octocorals. However, this value is significantly lower in gorgonian phenotypes compared to other soft corals. We present a conceptual framework describing and exploring the most relevant hypotheses regarding putative advantages of octocorals over scleractinians against environmental changes, including their ability to decrease energy expenses to overcome stress events, their lower dependency on autotrophy, and the type of interaction (facultative and flexible) with their symbiontsPD was funded by the Coordination for the Improvement of Higher Education Personnel (CAPES) social demand scholarship. AM was supported by a ‘Juan de la Cierva—Formación’ fellowship (FJC2020-044080-I) funded by the Spanish ‘Ministerio de Ciencia y Innovación’. PL was a grantee from the Brazilian National Research Foundation (CNPq)

Island biodiversity in peril: Anticipating a loss of mammals' functional diversity with future species extinctions

Islands are biodiversity hotspots that host unique assemblages. However, a substantial proportion of island species are threatened and their long-term survival is uncertain. Identifying and preserving vulnerable species has become a priority, but it is also essential to combine this information with other facets of biodiversity like functional diversity, to understand how future extinctions might affect ecosystem stability and functioning. Focusing on mammals, we (i) assessed how much functional space would be lost if threatened species go extinct, (ii) determined the minimum number of extinctions that would cause a significant functional loss, (iii) identified the characteristics (e.g., biotic, climatic, geographic, or orographic) of the islands most vulnerable to future changes in the functional space, and (iv) quantified how much of that potential functional loss would be offset by introduced species. Using trait information for 1474 mammal species occurring in 318 islands worldwide, we built trait probability density functions to quantify changes in functional richness and functional redundancy in each island if the mammals categorized by IUCN as threatened disappeared. We found that the extinction of threatened mammals would reduce the functional space in 63% of the assessed islands, although these extinctions in general would cause a reduction of less than 15% of their overall functional space. Also, on most islands, the extinction of just a few species would be sufficient to cause a significant loss of functional diversity. The potential functional loss would be higher on small, isolated, and/or species-rich islands, and, in general, the functional space lost would not be offset by introduced species. Our results show that the preservation of native species and their ecological roles remains crucial for maintaining the current functioning of island ecosystems. Therefore, conservation measures considering functional diversity are imperative to safeguard the unique functional roles of threatened mammal species on island

Landscape dynamics and diversification of the megadiverse South American freshwater fish fauna

Landscape dynamics are widely thought to govern the tempo and mode of continental radiations, yet the effects of river network rearrangements on dispersal and lineage diversification remain poorly understood. We integrated an unprecedented occurrence dataset of 4,967 species with a newly compiled, time-calibrated phylogeny of South American freshwater fishes—the most species-rich continental vertebrate fauna on Earth—to track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and Miocene (between 30 and 7 Ma) in association with major landscape evolution events. Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with Western Amazonia having the highest rates of in situ diversification, which led to it being an important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of the Northern Andes and associated formation of the modern transcontinental Amazon River. The combination of high diversification rates and extensive biotic interchange associated with Western Amazonia yielded its extraordinary contemporary richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics, which shaped the history of drainage basin connections, strongly affected the assembly and diversification of basin-wide fish fauna

Opportunities and challenges in marine macroecology

Submitted by Luciana Ferreira ([email protected]) on 2019-04-24T13:03:35Z No. of bitstreams: 2 Tese - André Menegotto Domingos - 2019.pdf: 10109411 bytes, checksum: 317c91b55d05dce4a699a7a1bf31ce66 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2019-04-24T14:05:56Z (GMT) No. of bitstreams: 2 Tese - André Menegotto Domingos - 2019.pdf: 10109411 bytes, checksum: 317c91b55d05dce4a699a7a1bf31ce66 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2019-04-24T14:05:56Z (GMT). No. of bitstreams: 2 Tese - André Menegotto Domingos - 2019.pdf: 10109411 bytes, checksum: 317c91b55d05dce4a699a7a1bf31ce66 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2019-02-27Macroecology, like other fields of ecology, has been historically a terrestrial discipline. However, marine biodiversity may contain key features for our understanding of global diversity patterns. Here, I explored this possibility by integrating knowledge about the marine environment with hypotheses and verbal models used to explain geographic variations in species diversity. Initially, I used marine productivity data to evaluate the effect of spatial subsidies on island plant diversity (Chapter 1). This study showed that, contrary to the proposed hypothesis, there is no evidence that allochthonous resources influence the diversity of small islands. Subsequently, I realized a conceptual review of the main mechanisms proposed to explain the latitudinal gradient of speciation under a marine perspective (chapter 2). In this review I show that, unlike the terrestrial system, each mechanism generates predictions totally different in the oceans. Nevertheless, it is also necessary to recognize and highlight the limitations that are inherent to marine biodiversity data, especially sample bias. Therefore, I evaluated here the state of our knowledge about the latitudinal distribution of different taxonomic groups (Chapter 3). In this study I reveal the existence of a species absence gradient that is strongly associated with low sampling effort in the tropics. Finally, I tested through a simulation model the efficiency of the empirical sample effort to accurately detect diversity patterns generated in a virtual ocean (Chapter 4). The result showed that the diversity gradient currently observed in the oceans does not differ from what is recorded after applying the same sampling effort in a simple null model. Therefore, I conclude that marine biodiversity may, indeed, be of great importance to understand macroecological patterns. However, there are still some geographic and taxonomic gaps that need to be addressed in order to explore this knowledge to its full potential.A macroecologia, assim como outros campos da ecologia, tem sido historicamente uma disciplina terrestre. No entanto, a biodiversidade marinha pode conter características fundamentais para a nossa compreensão dos padrões globais de diversidade. Aqui, eu explorei essa possibilidade integrando conhecimento sobre o ambiente marinho com hipóteses e modelos verbais utlilizados para explicar variações geográficas na diversidade de espécies. Inicialmente, eu utilizei dados de produtividade marinha para avaliar o efeito de subsídios espaciais na diversidade de plantas insulares (capítulo 1). Esse estudo mostrou que, ao contrário da hipótese proposta, não existem evidências de que recursos alóctones influenciam a diversidade de ilhas pequenas. Posteriormente, eu realizei uma revisão conceitual dos principais mecanismos propostos para explicar o gradiente latitudinal de especiação sob uma perspectiva marinha (capítulo 2). Nessa revisão eu mostro que, ao contrário do sistema terrestre, cada mecanismo gera uma predição totalmente diferente para os oceanos. No entanto, é preciso também reconhecer e destacar as limitações que são inerentes aos dados de biodiversidade marinha, principalmente o viés amostral. Por isso, eu avaliei aqui nosso grau de conhecimento sobre a distribuição latitudinal de diferentes grupos taxonômicos (capítulo 3). Nesse estudo eu revelo a existência de um gradiente de ausência de espécies que é fortemente associado com baixo esforço amostral nos trópicos. Por fim, eu testei através de um modelo de simulação a eficiêcia do esforço amostral empírico em detectar acuradamente padrões de diversidade gerados em um oceano virtual (capítulo 4). O resultado mostrou que o gradiente de diversidade atualmente observado nos oceanos não difere do que é registrado ao aplicar a mesma amostragem em um simples modelo nulo. Com isso, eu concluo que a biodiversidade marinha apresenta, de fato, um potencial enorme para a compreensão de fenômenos macroecológicos. No entanto, existem ainda algumas lacunas geográficas e taxonômicas que precisam ser preenchidas para que esse conhecimento possa ser explorado em todo seu potencial