Population structure and genetic connectivity of the freshwater shrimp Potimirim brasiliana Villalobos, 1959 inhabiting a continental island

ABSTRACT

Insular regions present peculiar characteristics, including small populations resulting from prolonged evolutionary isolation. Such conditions make these areas sensitive to anthropogenic changes. By consequence, these areas are interesting for studying genetic and adaptative processes. This study had two main goals: to evaluate the demographic structure (distribution, frequency of individuals in size classes, and sex ratio) and to assess the genetic diversity of a freshwater shrimp population of Potimirim brasiliana on the continental São Sebastião Island. Subsequently, population structure (size, abundance, and sex ratio) and genetic analyses (network haplotype and genetic distance of the mitochondrial marker cytochrome oxidase subunit 1 – COI) were analysed to compare the spatial distribution and connectivity of individuals along separated areas exposed to different conditions of dispersal. Three different areas were defined along the island (sheltered area – SA, exposed area – EA, and south extremity – SE). We found males and females in all areas except SE. The percentage of males was greater in the EA, that of non-ovigerous females was greater in the SE and that of ovigerous females was greater in the SA. Females were larger than males in all areas. No genetic structural difference was found between the studied areas and no genetic differences were detected in relation to the inland population. The strategy developed by P. brasiliana in the areas of the São Sebastião Island involves a differential occupation among the demographic groups in and maintaining connectivity between different and separated areas of the island by larval dispersal.

KEYWORDS:

• Atyidae
• Brazil
• freshwater decapods
• genetic structure
• São Sebastião Island

Acknowledgements

We express our gratitude to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for support during the development of this study (Temáticos Biota 2010/50188-8 and INTERCRUSTA 2018/13685-5). The collection of specimens conducted in this study complied with current applicable state and federal laws of Brazil (DIFAP/IBAMA/123/05) and the permanent license to FLM for collection of Zoological Material (No. 11777-1 MMA/IBAMA/SISBIO). We also thank IBAMA and the Instituto Florestal for supplied collecting permits (# 02027.000101/2006-10). JNT and NFCF thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), for PhD fellowships (respectively, 140957/2020-0 and PROEX DS – 88887.369727/2019-00 Financing code 001). FLM also thanks CNPq for a research fellowship (PQ 332253/2019-0). This study forms part of a postdoctoral project by ECM, supported by a fellowship from CAPES (# 563934/2005-0). We thank the anonymous reviewers for their suggestions to improve the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the CAPES [PROEX DS – Financing code 001]; CNPQ [PQ 332253/2019-0,PhD 140957/2020-0]; São Paulo Research Foundation (FAPESP) [Temático Biota 2010/50188-8, Temático Biota INTERCRUSTA 2018/13685-5; PROTAX 2021/08075-6].