Comparative geographic variation of selected southern African gerbils

Ramantswana, Tondani Madeleine (2013-03)

Thesis (MSc)--Stellenbosch University, 2013.

Thesis

ENGLISH ABSTRACT: The aims of this study were to describe and compare the geographic variation of D. auricularis and G. paeba, and determine whether the four recognised subspecies of the latter species are validusing traditional morphometrics and molecular data based on partial sequences of the mitochondrial cytochrome b (cyt b) gene.The traditional morphometric analyses were based on 12 cranial variables taken from 89 specimens from 54 localities forD.auricularis and 48 G. paeba specimens from 25 localities. Variables from both males and females were combined since univariate and multivariate analyses revealed there was no sexual dimorphism in the two species(Wilks' lambda, Λ = 0,942; p = 0.78 for D. auricularis and Λ = 0, 81; p = 0.82 for G. paeba). Univariate analysis revealed significant age variation and only age class II and IIIwere used for both species(for D. auricularis,Λ = 0,713; p = 0.035 and for G. paeba, Λ = 0, 748; p = 0.04). Multivariate analyses indicated that there was no intra-population variation which confirms that D. auricularis is a monotypic species. However, multivariate results for G.paebasuggest that two main operational taxonomic units exist.Variables differentiating these operational taxonomic unitsare mandibular length and rostral height.Overall, morphometricsresults suggest that four subspecies of G. paeba can be reduced to two subspecies. This includes G. p. paeba which has the widest distribution and consists of specimens from the South West Arid zone andG. p. coombsi comprises specimens from Southern Savanna Woodland. The molecular aspect of this project was also based onmuseum material, albeit from a reduced sample size: D. auricularis (N= 41 from 25 localities) and G. paeba (N=26 from 12 localities). A fragment of cyt b(216 - 394 bp) was successfully sequenced and analyzed for both species. Five haplotypes was found for the 41 D. auricularis specimens included. The most common haplotype, which characterized 38 of the specimens, was found across the distribution of species. Between six and seven mutational steps separated this common haplotype from the others.Haplotype diversity is low reflecting the large number of specimens sharing the common haplotype.The mantel test of D. auricularisshowed a non-significant (but positive) linear correlation between genetic and geographic distances (r = 0.013;p = 0.41) indicating no isolation by distance. Phylogenetic trees (Mr Bayes, NJ andMP)revealedtwo putative lineages within D. auricularis with sequence divergence values between these two clades ranged between 1.52% and 1.77%. Notwithstanding a lower sample size (N=26) and a shorter fragment analyzed (216 bp), more variation was detected in G. paebawith eleven haplotypes found. The two most divergent haplotypes are separated by 14 mutational step (6.48% uncorrected sequence divergence). Haplotype diversity was 0.4909 ± 0.1754 and nucleotide diversity 0.004714 ± 0.003846.A Mantel test showed non-significant but positive linear correlation (r = 0.13,p = 0.16) between geographic and genetic distance, supporting no isolation by distance. Phylogenetic analyses retrieved two clades with the sequence divergence between these clades ranging between 0.463 – 4.17%.Clade A is comprised of individuals from the Free State,Northern Cape and Limpopo Provinces. Clade B is comprised of individuals from Namibia, the Free State, Northern Cape and Eastern Cape Provinces. Overall, the two datasets are not congruent (for each species). For D. auricularis,morphometrics dataset recognize a single lineage and molecular dataset recognise two lineages. However, morphometric showed two OTUs and DNA data showed two lineages in G. paebawhich does not have sympatric distribution. The habitat preferences were probably responsible for shaping the morphological and geneticalvariation observed in these two sympatrically distributed gerbil species.

AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om te beskryf en die phylogeographic strukture van D. auricularis en G. paeba vergelyk, en bepaal of die vier erkende subspesie is geldig deur gebruik te maak van tradisionele morphometrics en molekulêre data gebaseer op gedeeltelike rye van die mitochondriale sitochroom B (cyt b) geen. Die tradisionele morfometriese ontleding is gebaseer op 12 kraniale veranderlikes wat van 89 monsters van 54 plekke vir D. auricularis en 48 G. paeba monsters van 25 plekke geneem. Veranderlikes van beide mans en vrouens is gekombineer sedert univariate en meerveranderlike ontleding aan die lig gebring dat daar was geen seksuele dimorfisme in die twee spesies (Wilks se lambda, Λ = 0942, p = 0,78 vir D. auricularis en Λ = 0, 81, p = 0,82 vir G. paeba). Eenveranderlike analise het aan die lig gebring beduidende ouderdom variasie en slegs ouderdom klas II en III is wat gebruik word vir beide spesies (vir D. auricularis, Λ = 0713; p = 0,035 en G. paeba, Λ = 0, 748, p = 0.04). Meerveranderlike ontleding het aangedui dat daar nie 'n intra-bevolking variasie wat bevestig dat D. auricularis is' n monotipiese spesie. Maar, meerveranderlike resultate vir G. paeba stel voor dat drie hoof operasionele taksonomiese eenhede bestaan. Veranderlikes die onderskeid van hierdie operasionele taksonomiese eenhede is die breedte van die eerste molêre, skedel lengte en rostrale hoogte. Overall, morphometrics resultate dui daarop dat vier subspesies van G. paeba drie subspesies kan verminder word. Dit sluit G. p. paeba wat die wydste verspreiding en die bestaan van die monsters van die xeric en Mesic spesies [Namibië en Suid-Afrika (Noord-Kaap, Wes-Kaap en Oos-Kaap Provinsie)], G. p. coombsi bestaan uit monsters van die Soutpansberg gebied en G. C. kalaharicus bestaan uit individue uit Botswana, wat binne die Mesic gebied versprei is. Die molekulêre aspek van hierdie projek is ook gebaseer op die museum materiaal van D.auricularis (N = 41 van 25 plekke) en G. paeba (N = 26 van 12 plekke). 'N fragment van cyt b (216 – 394 BP) was suksesvol volgorde en geanaliseer vir beide spesies. Vyf haplotypes was gevind vir die 41 D. auricularis monsters ingesluit. Die mees algemene haplotype, wat gekenmerk word 38 van die monsters, is gevind oor die verspreiding van spesies. Tussen ses en sewe mutasie stappe hierdie gemeenskaplike haplotype van die ander geskei. Haplotype diversiteit laag is dit die groot aantal monsters deel van die gemeenskaplike haplotype. Die mantel toets D. auricularis het 'n nie-beduidende (positiewe) lineêre verband tussen genetiese en geografiese afstande (p = 0,41; r = 0,013) wat aandui dat geen isolasie deur die afstand. Filogenetiese stambome (Mnr Bayes, NJ en LP) het aan die lig gebring twee vermeende afstammelinge binne D. auricularis volgorde divergensie waardes tussen hierdie twee clades gewissel tussen 1,52% en 1,77%. Ten spyte van 'n laer steekproefgrootte (N = 26) en' n korter fragment ontleed (216 bp), is meer variasie bespeur in G. paeba met elf haplotypes word. Die twee mees uiteenlopende haplotypes word geskei deur 14 mutasie stap (6,48% nie-reggestelde volgorde divergensie). Haplotype diversiteit 0,4909 ± 0,1754 en nukleotied diversiteit 0,004714 ± 0,003846. 'N Mantel toets het getoon nie-betekenisvolle maar positiewe lineêre korrelasie (p = 0,16; r = 0,129) tussen die geografiese en genetiese afstand, geen isolasie deur die afstand te ondersteun. Filogenetiese ontleding opgespoor twee clades met die volgorde verskille tussen hierdie clades wissel tussen 0,463 – 4,17%. Clade 'n bestaan uit individue van die Vrystaat, Noord-Kaap en Limpopo provinsies. Clade B bestaan uit individue uit Namibië, die Vrystaat, Noord-Kaap en Oos-Kaap. Overall, die twee datastelle is nie kongruent (vir elke spesie). Vir D. auricularis, morphometrics dataset herken 'n enkele afkoms en molekulêre datastel erken twee geslagte. Maar, morfometriese gewys drie Otus en DNS-data het twee geslagte in die G. paeba. Die habitatvoorkeure was waarskynlik verantwoordelik vir die vorming van die morfologiese en genetische variasie in hierdie twee sympatrically versprei Gerbil spesies waargeneem.

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