Research output

Article in Journal ()

Tracing ancient evolutionary divergence in parasites

Citation
Tinsley RC & Tinsley MC (2016) Tracing ancient evolutionary divergence in parasites, Parasitology, 143 (14), pp. 1902-1916.

Abstract
For parasitic platyhelminths that generally lack a fossil record, there is little information on the pathways of morphological change during evolution. Polystomatid monogeneans are notable for their evolutionary diversification, having originated from ancestors on fish and radiated in parallel with tetrapod vertebrates over more than 425 million years. This study focuses on the genus Polystomoides that occurs almost worldwide on freshwater chelonian reptiles. Morphometric data show a major divergence in structural adaptations for attachment; this correlates with a dichotomy in micro-environmental conditions in habitats within the hosts. Species infecting the urinary tract have attachment organs with large hamuli and small suckers; species in the oro-nasal tract differ fundamentally, having small hamuli and large suckers. Zoogeographical and molecular evidence supports ancient separation of these site-specific clades: a new genus is proposed – Uropolystomoides – containing urinary tract species distinct from Polystomoides sensu stricto in oro-nasal sites. Aside from differences in attachment adaptations, body plans have probably changed little over perhaps 150 million years. This case contrasts markedly with polystomatids in other vertebrate groups where major morphological changes have evolved over much shorter timescales; the chelonian parasites show highly stable morphology across their global distribution over a long period of evolution, exemplifying ‘living fossils’.

Keywords
Monogenea; Polystomatidae; Polystomoides; Uropolystomoides; living fossils; site-specific attachment adaptations

StatusPublished
AuthorsTinsley Richard C, Tinsley M C
Publication date12/2016
Publication date online31/08/2016
Date accepted by journal13/06/2016
PublisherCambridge University Press
ISSN 0031-1820
LanguageEnglish

Journal
Parasitology: Volume 143, Issue 14

© University of Stirling FK9 4LA Scotland UK • Telephone +44 1786 473171 • Scottish Charity No SC011159
My Portal