Evolution of spermatophore transfer mechanisms in Decapodiformes (Mollusca: Cephalopoda)

• Grant number: 23/09834-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2024
• End date: June 30, 2025
• Field of knowledge: Biological Sciences - Zoology - Morphology of Recent Groups
• Principal Investigator: José Eduardo Amoroso Rodriguez Marian
• Grantee: Dimas Kenji Sakamoto
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/02746-9 - Diving in the Mesozoic Marine Revolution from the perspective of benthic and nektonic mollusks, AP.PNGP.PI

Abstract

Cephalopods are potentially interesting models for studies on evolutionary convergences, as suggested by recent investigations of spermatophore transfer strategies in Decapodiformes (e.g., cuttlefishes and squids). It is hypothesized that the evolution of these strategies were biased by historical transitions between marine habitats, due to the presence of similar strategies in distantly related lineages that occupy the same environment. For instance, the transfer of spermatophores through the hectocotylus to a specialized receptacle in the female is characteristic of coastal and epi/mesopelagic species, while the transfer of externally implanted spermatophores through a "penis" is typical of deep-sea species. This study aims to test this hypothesis by reconstructing ancestral states of these traits (hectocotylus and "penis") and testing their correlation with the historical colonization of pelagic zones by the clade. To do so, we will use data from literature and analyses of specimens from museum collections and those obtained through a collaborative network to create a character matrix of habitats and traits related to spermatophore transfer. The ancestral states of morphological characters and habitat types will then be estimated based on phylogenies inferred through molecular data available in public databases; finally, we will test whether these traits are correlated with the habitat. Moreover, 12 species representative of key lineages of Decapodiformes were selected for detailed analyses using light, electron and confocal microscopy, with the purpose of understanding their functional basis. These efforts will not only deepen our knowledge of cephalopod reproductive behavior, but also shed light on evolutionary convergences in marine organisms, with wider implications that extrapolate the model group.