Integrative Approaches to the Systematics and Conservation of the Reptiles of the Cape Verde Islands.

PhD Thesis. Departamento de Biologia Faculdade de Ciências da Universidade do Porto

Volltext: http://www.scvz.org/pdf/TeseRVLowRes_ii.pdf


Two of the main sensitivities of Conservation Biogeography are the inadequacies in taxonomic and chorological data, the so-called Linnean and Wallacean shortfalls, respectively. These shortfalls increase in the more remote areas such as oceanic islands. This thesis contributed to dilute those shortfalls in one of those remote areas, the Cape Verde Islands, for one of its least studied group, the reptiles.The specific goals of this thesis were related to answering to what diversity occurs there and to address putative biogeographic factors that explain why diversity is unevenly distributed. Then, it is aimed to answer where this biodiversity can be found and, based on all the gathered data, to plan how to better protect it at different levels.

First, the phylogeographic patterns of terrestrial reptiles were studied to identify an introduced agamid and cryptic endemic taxa of the three genera (Hemidactylus, Tarentola and Chioninia) and to clarify their systematics. The new introduced taxon in Cape Verde was identified as Agama agama. Also, some endemic subspecies were upgraded to the specific status and three new cryptic species (Hemidactylus lopezjuradoi, Tarentola bocageiand T. fogoensis) and subspecies (Chioninia vaillanti xanthotis, C. spinalis boavistensis and C. s. santiagoensis) were described using an integrative approach combining morphological, genetic and population analyses. These studies highlighted the usefulness of integrative datasets in the fields of Taxonomy and Phylogeography and how they can improve the performance of taxa estimations. In addition, the origin of the introduced Agama and the colonisation patterns of the endemic taxa were inferred and several historical and environmental factors, such as the Pleistocene sea-level falls and altitude, were related with the uneven distribution of diversity at intraspecific level. Low intraspecific divergence between reptile lineages of the same island has been explained by the recent volcanic activity and high ecological stress that could lead to population extinctions, and the low habitat diversity within some islands that could restrain opportunities for allopatric diversification.

Secondly, extensive sampling and bibliographic chorological data were compiled to produce and updated distribution atlas for all taxa addressing doubtful or erroneous records and to develop predictive maps of occurrence based on ecological niche-based models for most of the endemic taxa. This data also allowed the detection of the wide-spreading of the introduced H. angulatus in Santiago and Boavista and the colonisation of two new islands by the exotic H. mabouia. In addition, it allowed updating the conservation status for the endemic taxa showing that around half of them are threatened under the IUCN criteria and that the most frequent classifying criterion was related to restricted geographic range. The most pervasive threats identified are related to natural disasters, as droughts and volcanic activity, intrinsic factors, such as low population densities and restricted range, and introduced species.

Finally, this work also demonstrated how ecological niche-based models are useful tools to infer ranges on relatively under-sampled and remote areas with high accuracies and how they can be applied to conservation, maximizing efficiency of reserve designs. Results depicted that in Santa Luzia, Branco, Raso, Sal, Boavista, Maio and Rombos designation of new protected areas is not a priority since the ones that are going to be implemented will reach the conservation targets for all identified evolutionary significant units of those islands and islets. On the other hand, new or modified reserves should be implemented on the remaining islands to cover all identified lineages of Cape Verdean reptiles. This measure is especially important in Fogo and Brava, where no planning unit selected by the area prioritisation scenarios is within the protected areas limits and no protected area is planned, respectively.
Altogether, this work exemplifies the usefulness of integrating different disciplines to more effectively allowing systematic conservation planning of biodiversity.

Gelesen 1055 mal Letzte Änderung am Samstag, 11 November 2017 16:43
© Peter Dollinger, Zoo Office Bern hyperworx