Conservation Biogeography of the Cheirogaleidae

Abstract

Habitat destruction, anthropogenic disturbance and environmental change are among the primary threats to the forests of Madagascar and the endemic lemurs that inhabit them. The Cheirogaleidae are the smallest of all the lemurs, and are particularly vulnerable to forest fragmentation due to their small body size and inability to travel through the open spaces between isolated forest fragments. However, many cheirogaleid lemurs thrive within highly degraded habitats, and it is now thought that this family of lemurs may be somewhat resilient to habitat degradation and anthropogenic threats. In this thesis, I explored how the demography of the Cheirogaleidae is affected and limited by a range of habitat-related, environmental and anthropogenic factors, and how the distribution of their forest habitat is likely to be affected by future climate change. Due to the COVID-19 pandemic, no new field data could be collected to investigate the specific research questions asked in this thesis, so I used published data to compile a meta-database of cheirogaleid lemur distributions and densities, which I subsequently analysed using meta-analyses, ecological niche modelling and GIS-based approaches. Surprisingly, I found that the distribution of Madagascar’s forest is unlikely to be negatively impacted by future climate change, and forest area-suitability may in fact increase under both mitigated and unmitigated future climate scenarios. The insensitivity of Madagascar’s forests to climate was also mirrored in the Cheirogaleidae themselves. Meta-analysis results revealed that cheirogaleid lemur density is often little affected by forest quality and anthropogenic disturbance, and the Microcebus genus appears
to actually respond positively to degradation and disturbance factors, as also highlighted by their high densities outside Madagascar’s protected area network. However, I also found that habitat, environmental and climatic factors influence the different genera of the Cheirogaleidae interspecifically, and this was also reflected at the species level within the Cheirogaleus and Phaner genera when analysed with ecological niche models. Some species within the Cheirogaleus and Phaner genera are more ecologically-specialized, have more restricted geographic ranges, and are thus more vulnerable to deforestation and anthropogenic threats. Overall, my findings highlight that the Cheirogaleidae are indeed highly resilient and adaptable to deforestation, disturbance and environmental change, which is highly encouraging for their conservation. However, all of the Cheirogaleidae require forest cover to survive, and continued protection of their habitat is required to ensure their survival, especially for the most sparsely-distributed, threatened species.

Date of Award	28 Sept 2021
Original language	English
Awarding Institution	University of Bristol
Supervisor	Grainne Mccabe (Supervisor), Marc W Holderied (Supervisor) & Sam Cotton (Supervisor)