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Accueil du site → Doctorat → Allemagne → 2006 → Evolutionary history of Southern Arabian faunal elements with a special focus on habitat fragmentation of two model organisms, Reissita simonyi (REBEL, 1899 ; Lepidoptera : Zygaenidae) and Hyla savignyi (AUDOUIN, 1827 ; Amphibia : Hylidae)

Rheinischen Friedrich-Wihelm-Universität zu Bonn (2006)

Evolutionary history of Southern Arabian faunal elements with a special focus on habitat fragmentation of two model organisms, Reissita simonyi (REBEL, 1899 ; Lepidoptera : Zygaenidae) and Hyla savignyi (AUDOUIN, 1827 ; Amphibia : Hylidae)

Klütsch, Cornelya F. C.

Titre : Evolutionary history of Southern Arabian faunal elements with a special focus on habitat fragmentation of two model organisms, Reissita simonyi (REBEL, 1899 ; Lepidoptera : Zygaenidae) and Hyla savignyi (AUDOUIN, 1827 ; Amphibia : Hylidae)

Auteur : Klütsch, Cornelya F. C.

Université de soutenance : Rheinischen Friedrich-Wihelm-Universität zu Bonn

Grade : Dr. rer. nat. 2006

Résumé
Habitat fragmentation is assumed to be one of the major factors for geneticseparation of populations. Natural fragmentation of habitats may be caused byclimatic changes and their consequences (e. g. desertification), as well asby natural disasters like bush fires or inundations. Recently, habitat fragmentationincreased due to human impact. Only little is known about habitat fragmentationand population differentiation as well as distributional ranges of faunal elementsin Southern Arabia. Therefore, detailed studies for this geographical area werestill lacking. The two faunal elements chosen for this study were Reissita simonyi(Lepidoptera : Zygaenidae) and Hyla savignyi (Amphibia : Hylidae). These speciesshow special ecological features, which make them presumable sensitive to habitatfragmentation. Moreover, both species show different dispersion abilities, whichis a crucial factor to maintain gene flow also over higher distances betweenpopulations. Reissita simonyi is a flying diurnal moth, which is assumed tomigrate longer distances than Hyla savignyi. Amphibians often show high pondfidelity and generally migrate only a few kilometers, although long-distancemigration was found in a closely related species, H. arborea. Results indicated for both species heterozygosity deficiencies and high inbreedingcoefficients. Furthermore, high FST values between population pairs in H. savignyiindicate restricted gene flow between patches. Moreover, in both species a significantcorrelation of genetic differentiation and geographical distance (isolationby distance) was found. Besides, in both species a significant correlation betweenaltitude and genetic differentiation was present. Thus, in Hyla savignyi population structure is strongly formed by geographicaldistance and high genetic differentiation in general (FST), which is consistentwith the assumption of low dispersion ability. However, it is also shown thatnot only the aforementioned effects shaped the genetic structure of H. savignyipopulations, but also by long distance gene flow can be detected. The populationstructure of H. savignyi showed a clear substructure into three major groups,which showed a North to South extension. Within these groups, no isolation bydistance effects could be observed. This indicates a higher connectivity withinthan among groups. In R. simonyi, the division in two subspecies could be confirmed with geneticdata. The genetic analysis revealed a significant separation of two groups,which are identical with the subspecies. This clear pattern was supported bya greater genetic differentiation between groups in comparison to within-groupdifferentiation. Thus, within subspecies, the genetic differentiation was lower,which indicates a higher connectivity within subspecies. In total, the degreeof genetic differentiation was much lower in R. simonyi than in H. savignyi.Hence, it is concluded that populations of R. simonyi are more genetically tiedthan populations of H. savignyi, besides high inbreeding coefficients and heterozygositydeficiencies, which are assumed to be based on null alleles. One explanationfor this low genetic differentiation is surely the higher dispersion abilitycaused by the ability to fly and therefore, the potential to migrate over largergeographical distances. A second possible explanation is that the larval foodplants occur with a sufficient frequency and therefore a strong isolation ofpopulations of R. simonyi is avoided. Finally, the data supported the well knownphenomenon “top-hopping” in Lepidoptera, which is the ability tomigrate from one hill to another very easily. A combination of all three possibilitiesis the most likely explanation for the low genetic differentiation found inR. simonyi.

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