Molecular phylogeny and evolution of the Ectemnorhinus group of weevils in the Prince Edward Islands

• Main Author: Grobler, Gert Cornelius
• Other Authors: Bastos, Armanda D.S., Chown, Steven Loudon, Chimimba, Christian Timothy
• Format: Thesis
• Language: unknown
• Published: University of Pretoria 2013
• Subjects: Phylogeny; Marion Island; Curculionidae; Evolution; Ectemnorhinus group of weevils; Invasion biology; Speciation; Dispersal; Biogeography; MTDNA; Conservation; Sub-antarctic; Prince Edward Island; Coi gene; Phylogeography; Coleoptera; Southern Ocean Islands; UCTD; Antarctic; Southern Ocean; Indian; Antarc*; Prince Edward Islands
• Online Access: http://hdl.handle.net/2263/27617; http://upetd.up.ac.za/thesis/available/etd-08282012-092251/

All previous taxonomic studies on the Ectemnorhinus group of weevils have been based primarily on morphological data. While these studies are invaluable, some questions can only be addressed adequately through molecular studies. This is especially true when studying the genetic relationships and phylogeograpic patterns of taxa endemic to the South Indian Ocean Province (SIP) biotas that have long been controversial. The Ectemnorhinus group of genera is a monophyletic unit of weevils endemic to the region. The present study focused mainly on the Ectemnorhinus group of weevils found on the Prince Edward Islands archipelago (PEIA). The mitochondrial cytochrome oxidase I gene was targeted when investigating relationships among members of this weevil group. On the PEIA, it is important to note that Marion Island (MI) and Prince Edward Island (PEI) differ in terms of alien invasive species, such as the introduced house mouse Mus musculus and in conservation management strategies. Since emergence, a series of volcanic and glaciation events have occurred on Marion Island, whilst Prince Edward Island has remained largely unaffected by glaciation. Phylogenetic analyses revealed the presence of two genetically and morphometrically distinct species of Ectemnorhinus weevils on PEI, whilst evidence for a single species, comprising diverse genetically discrete populations was found on MI. Based on these results, the species unique to PEI has been designated E. kuscheli n. sp., whilst the present study confirmed the synonymy between E. similis and E. marioni, the two species originally described from MI. Ectemnorhinus kucheli appears to be restricted to PEI, whereas E. similis occurs on both MI and PEI. When investigating the population dynamics of the Ectemnorhinus weevils on the PEIA, the data indicated that PEI was the first of the two islands of the PEIA to be colonized by Ectemnorhinus weevils, at an estimated time of coalescence of approximately 0.3116 million years ago (MYA). The PEI population then acted as the source ...