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Assessing the effects of habitat fragmentation on amphibian populations in Madagascar’s Central Highlands

Mullin, Katherine 2023. Assessing the effects of habitat fragmentation on amphibian populations in Madagascar’s Central Highlands. PhD Thesis, Cardiff University.
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Habitat loss, degradation, and fragmentation present significant threats to biodiversity globally. Amphibians are among the most threatened vertebrates, yet the available conservation literature covering the effects of habitat fragmentation on amphibians, especially using genetic methods, is not comprehensive. Within this thesis, a combination of field data, mitochondrial DNA barcoding and next generation sequencing were integrated to evaluate ecological and evolutionary mechanisms that influence current patterns of amphibian diversity across a fragmented landscape in Madagascar’s Central Highlands. Amphibian diversity and community composition differed in forest fragments, both influenced by fragment size and isolation. Species and phylogenetic diversity were diminished and communities in fragments were subsets of those in more continuous forest. Diversity was lost across the phylogeny, as opposed to losing entire clades of closely related species, with the naturally rare and terrestrial species most commonly lost. Our results suggest that local forest fragmentation is recent, with evidence of extinction debt, but that the Central Highlands has long been a matrix of savannah grasslands and forest. Consequently, this recent habitat loss timeline may not have been sufficient to negatively influence genetic diversity, and I conclude that the absence of some species in the smaller fragments is likely due to ecological factors as opposed to genetic erosion. My results add knowledge of the cryptic diversity remaining in forest fragments in this region and demonstrate the importance of conserving and re-connecting the remnant forest fragments. This thesis expands the understanding of the effects of habitat fragmentation on amphibian diversity and provides the first use of phylodiversity and population genetics to examine the impacts of habitat fragmentation on amphibians in Madagascar. The results of this thesis can directly be used as a baseline for future conservation and management of the amphibians studied, and our results can guide reforestation efforts in the region.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > Q Science (General)
Date of First Compliant Deposit: 9 May 2023
Last Modified: 10 May 2023 10:51

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