Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DATE: 12/05/2023
TIME: 08:30
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How the environment drives the evolution of the Brazilian scaled-sardines


genetic diversity; genomics; population connectivity; fisheries management; climate change; niche modelling.

BIG AREA: Ciências Biológicas
AREA: Zoologia
SUBÁREA: Zoologia Aplicada
SPECIALTY: Conservação das Espécies Animais

Biodiversity loss is currently a major concern in conservation and evolutionary biology. In the marine environment, continuous overexploitation of natural resources drives natural populations to collapse, increases species’ extinction risk, compromises ecosystems functioning, and the numerous goods and services provided to human communities, including fisheries. Global warming can aggravate this scenario, as numerous species are already living closer to their thermal limits, especially tropical ones. Understanding the environmental features that drive population dynamics is an important step towards establishing the sustainable use of natural resources, once the environment influence species’ distribution, diversity and, ultimately, their evolution. In the present thesis, divided in two chapters, I used genomic and ecological data to understand how the environment guides the evolution of scaled sardines Harengula sp., a putative undescribed species at the Brazilian coast. In the first chapter, I combined ecological modelling of the Last Glacial Maximum (LGM, ~21 kya) with genomic modelling (DArTseq data) to estimate how past climatic cycles impacted the demographic history of Harengula sp. in the Atlantic Southwest. I found that this lineage is structured by depth and salinity in two populations that reflect the shallow-water habitat expansion following the LGM: a large, more diverse and expanding at the Brazilian coast, (coastal population) and a smaller, more inbred, and stable at the oceanic archipelago of Fernando de Noronha (FNO, island population). The status of the FNO population is more sensible, considering that Harengula sp. is of fundamental commercial and ecologic importance as the only sardine species in the archipelago, where conflicts remain unsolved between park managers and local fishers demanding the exploitation of this fishery in the park’s no-take zone. Asymmetric gene flow from the coastal to the island population, against the flow of main oceanic currents in the region, reinforces the need for different management strategies for these two populations. In the second chapter, I used ecological niche and larval dispersal models to understand the dynamics of habitat occupation in the present climate and estimate habitat change given a future of global warming. Niche modelling indicates southward shift and range contraction of the scaled sardines Harengula sp., a change that increases as the scenarios modelled for the future are aggravated. Larval dispersal models indicate that marine protected areas (MPAs) in islands, such as FNO and Abrolhos, currently act as a biodiversity and fishery spillover to the coastal mainland, potentially minimizing the effects of overfishing at the Brazilian coast and increasing population resilience to cope with habitat change. However, distantly located MPAs (>1,000 km) such as Trindade-Martim Vaz, are not a source of sardines’ larvae to the coast. The larval connection between FNO and the Brazilian coast contradicts the aforementioned genomic data, suggesting that although this species has dispersal potential, the high mortality of early life stages hinders reaching and settling in these areas. Combining methods allowed uncovering cryptic genetic diversity, detecting population dynamics, estimating dispersal ability, habitat change and its impacts on the evolutionary trajectory of an undescribed species in the Atlantic Southwest. For small, abundant species, these methods are also adequate to tackle some demands of fisheries management (taxonomic identity, geographic distribution, number of stocks and population dynamics), which together with fishing statistics can help in the sustainable management of marine resources.

Presidente - 1865104 - SERGIO MAIA QUEIROZ LIMA
Externa ao Programa - 1914239 - MIRIAM PLAZA PINTO - UFRNExterno à Instituição - LARISSA SOUZA ARANTES - IWM
Externo à Instituição - MARCELO COELHO MIGUEL GEHARA - rutgers
Notícia cadastrada em: 12/05/2023 08:07
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