Understanding diversity patterns, speciation, and biogeography of shallow-water marine organisms in the Atlantic realm

Ever since the works of Charles Darwin in the 19th century the formation of species (speciation) in the Ocean has been a topic of debate. The dispersal capacities of marine species resulting from their swimming abilities (e.g., fish) or from the drift of larvae by oceanic currents between distant places, together with the apparent absence of barriers in the oceans poses a serious challenge to the concept of speciation. Under such conditions where isolation seems difficult, marine speciation is expected to be uncommon yet is clearly not rare and for example some groups of animals like snails, crustaceans, or worms depict a remarkable diversity with thousands of species. Most species occurring in the Atlantic Ocean are unique and not found in other places like the Pacific or Indian oceans. The diversity and distinctiveness of the Atlantic is likely the result of tectonic, oceanographic, and climatic events that occurred since the Miocene about 18 million years ago. Yet, how exactly and when in time events have impacted the origin and extinction of species is not well understood. The MarDivA project seeks to understand the processes that resulted in the origin and current diversity of species in the Atlantic and the time these events occurred. To fulfil these goals snails of the genus Haminoea are used as model-organisms and their shells, morphology, DNA, and fossil record will be studied and combined with evolutionary theory. How many species are there and why some regions are more diverse than others? Can speciation occur in the same area or only when populations become isolated? Are there any periods in time when speciation was more common? Is there any relation between speciation and climate change? These are some of the questions that MarDivA will try to answer.

Tectonic, oceanographic, and climatic events that occurred particularly between the Miocene and Pleistocene epochs (e.g., closure of the Tethys Sea, uplift of the Isthmus of Panama, Benguela current, intermittent opening of the Bering Strait, glacial cycles, sea-level oscillations), have contributed to shape the identity of the Atlantic biome. The impact of these events created opportunities for speciation and modified the barriers for species dispersal and consequently the distribution of species, leading to changes in biodiversity composition. Nevertheless, the effectiveness of these barriers and the timing of impacts on the rearrangement of biotic communities are still questioned and not fully understood particularly in soft-bottom shallow water faunas. The main objective of MarDivA is to understand the time and processes underlying the origin and diversification of Atlantic shallow-water species, using Haminoea gastropods as a case-study. A multidisciplinary approach using original morpho-anatomical data, micro-CT scan, phylogenetic inference based on mitogenomes, will be combined with biogeographic models, and oceanographic and historical climatic data, and used as a proxy to answer questions about the diversity and distribution of species, time, mode, and geography of speciation. This project builds, develop, and strengths capacities on areas of major relevance in biodiversity research, natural history museology, and societal concern, such as, the inventorying of global marine biological diversity, the origin and extinction of life in the Ocean and its relation with historical and current climatic events. Collaborative actions between museums (research and non-research institutions) are promoted and research data is used to establish educational programmes aiming to raise understanding and awareness among society.