Allopatric speciation in the littoral gastropod genus Osilinus Philippi, 1847 (Gastropoda: Trochidae) at the Atlantic/Mediterranean interface

• Main Author: Preston, Joanne
• Format: Thesis
• Language: English
• Published: University of Southampton 2003
• Subjects: Northeast Atlantic
• Online Access: https://eprints.soton.ac.uk/465235/; https://eprints.soton.ac.uk/465235/1/932467.pdf

This thesis addresses the problem of speciation in marine ecosystems using a phylogeographic approach. The overall aim was to present a model of speciation in the intertidal gastropod Osilinus Philippi, 1847 in the Northeast Atlantic and Mediterranean. The study of speciation in the natural environment is essentially the observation of patterns, such as geographic distribution, evolutionary relationships and taxonomic diversity. Hypotheses to explain these patterns are based largely on the allopatric model of speciation, and the process of vicariance and dispersal. Chapter 1 presents an overview of the taxonomic status and biogeography of Osilinus at the outset of the work to demonstrate the value of using this genus as a model organism for understanding speciation in the marine environment. The challenges faced by studying speciation in the marine environment are summarized. A case is made for using the Northeast Atlantic and Mediterranean as an ideal model system for furthering our understanding of this subject. Current models of speciation are reviewed and placed in the context of marine ecosystems in chapter 2. Palaeoceanography can be used to contextualise temporal patterns of evolution, and infer processes that have resulted in the biogeography of a marine species. An overview of the palaeoceanography of the Northeast Atlantic and Mediterranean within timescales relevant to the speciation of Osilinus is also given. A description of species and the geographic distribution of each species are presented in chapter 3 in light of taxonomic clarity (in part based on Chapter 6). Hypotheses are presented on the mechanisms (palaeoceanographic events) that may have caused the observed radiation of Osilinus, as suggested by their present distribution.