Tejangkura, T (2012) Hybrid zone genetics and within-island diversity of the gecko Tarentola boettgeri. Doctoral thesis, Liverpool John Moores University.

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Abstract

This study builds on a previous study that demonstrates the existence of deep mitochondrial lineages in the gecko Tarentola boettgeri within Gran Canaria (Gubitz et al. 2005). Here, I identified and analyzed the area where the two most divergent mitochondrial •lineages meet. The primary aim was to examine how geographical structuring of mtDNA has been maintained after secondary contact. MtDNA analyses used a 608 basepair fragment of the cytochrome b (cyt b) gene from 389 individuals sampled from 14 populations along a 32 km southeast (SE) transect across Gran Canaria. It revealed a low degree of mtDNA admixture and negligible gene flow across the contact zone. This led to the hypothesis that reproductive barriers may have formed between populations from different mtDNA lineages. Analyses of seven body dimension and scalation characters revealed that spatial patterns of morphological changes were not associated with the transition in mtDNA lineage frequency across the transect. This contrasted with another lizard species on the same island, Chalcides sexlineatus, in which phylogeography and morphology are highly correlated. This study identified ten unique microsatellite markers in T. boettgeri. Like morphology, analyses of these microsatellites did not reveal a pronounced spatial pattern of differentiation in the nuclear genome. These results appear to reject the hypothesis of a physical or genetic barrier to reproduction. Studies of micro satellites also suggested that T. boettgeri is a low dispersal species and this might explain the persistence of mtDNA contact zone. However, evidence of concordant spatial patterns between divergence in the nuclear genome and morphology was detected. The discordant spatial patterns of mitochondrial and nuclear genotype frequencies do not appear to be explained by sex-biased gene flow, and are difficult to understand because of expected interactions between the two genomes. Thus, further investigation is suggested to allow clarification of the causes of mito-nuclear discordance in T. boettgeri.

Item Type:	Thesis (Doctoral)
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QH Natural history > QH426 Genetics Q Science > QL Zoology
Divisions:	Natural Sciences & Psychology (closed 31 Aug 19)
Date Deposited:	31 Mar 2017 10:42
Last Modified:	03 Sep 2021 23:31
URI:	https://researchonline.ljmu.ac.uk/id/eprint/6162

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