Sponsor
Portland State University. Department of Biology
First Advisor
Daniel Ballhorn
Term of Graduation
Winter 2025
Date of Publication
3-12-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (Ph.D.) in Biology
Department
Biology
Language
English
Subjects
Afrotropical, Bat, Cameroon, Chiroptera, Diversity, Sky islands
Physical Description
1 online resource (xi, 234 pages)
Abstract
Humans are altering biological communities on local to global scales, driving profound changes in biodiversity and ecosystem functioning. However, significant gaps and biases in biodiversity data hinder our understanding of ecosystem interactions, making it challenging to develop effective, data-driven policies to protect remaining biodiversity. Bats, the second most species-rich groups of mammals, have a global distribution, and perform a broad array of vital ecosystem functions. Their diversity peaks in the tropics, where they often constitute more than 50% of mammal species diversity. The Afrotropics host substantial bat diversity, yet have historically been perceived as having lower species richness compared to other tropical regions. Recent studies, however, reveal that this perception has been influenced by sampling biases and cryptic diversity, masking the true extent of Afrotropical bat diversity. An important yet understudied component of Afrotropical landscapes are inselbergs, or isolated rock outcrops forming discrete ecosystems. The unique habitats play a vital role in shaping local and regional bat diversity by providing varied niche space, supporting hydrological networks, and contributing to ecosystem stability.
In the first study (Chapter 2), we examined the morphological and molecular (mitochondrial Cytochrome b) variation within the Tropical African vespertilionid bat genus Pseudoromicia. This analysis revealed the existence of a new species Pseudoromicia mbamminkom, from the Mbam Minkom Massif in the Centre Region of Cameroon. Phylogenetic analysis placed this species within a clade alongside P. roseveari and P. kityoi. Pseudoromicia mbamminkom was diagnosed through sequence data, as well as craniodental characters although it is morphologically similar to its sister taxon, P. kityoi, from Uganda. We proposed assigning the species to the IUCN Data Deficient category, as the description is based on the capture of a single specimen. However, its conservation status might warrant concern, given the threats to the Mbam Minkom Massif ecosystem from insufficient legal protection and increasing human pressure.
In the second study (Chapter 3), we reported findings from two expeditions (2019 and 2022) to the Mbam Minkom Massif and describe the bat fauna of this tropical inselberg. Over the two expeditions, 36 bat species from 21 genera and six families were recorded. Notably, our findings include two new species records for Cameroon, additional records of Pseudoromicia mbamminkom, and the presence of several threatened species. Detailed species accounts are provided, including locality records, capture sites, taxonomic notes, and echolocation call data. Sampling curves indicated a species richness of 42 with adequate coverage but suggested the potential for undetected species, emphasizing the need for further surveys to develop a comprehensive species checklist. This study highlighted the remarkable diversity and ecological importance of the Mbam Minkom Massif and its surrounding forest, an ecosystem under threat from deforestation and increasing human activity.
In the final study (Chapter 4), we investigated the influence of the Mbam Minkom Massif on bat diversity by comparing the forest near the inselberg to a forest distant to the inselberg in homogenous lowlands. Using a multifaceted approach, we examined alpha and beta taxonomic, functional, and phylogenetic diversity. Results showed significantly higher taxonomic and functional diversity near the inselberg, likely due to increased habitat complexity and rocky terrain suitable for roosting. Notably, three cave-roosting species (R. landeri, Hipposideros curtus, and Rousettus aegyptiacus) were detected exclusively near the inselberg. Phylogenetic alpha diversity showed similar patterns but with less pronounced differences and no significant variation in richness or diversity. The observed patterns of taxonomic, functional, and phylogenetic diversity near the inselberg reflect the interplay of localized ecological factors and broader biogeographic processes shaping bat communities near the inselberg and in the distant, homogenous lowland landscape. These findings highlight the critical role of Mbam Minkom Massif in promoting taxonomic and functional diversity while enhancing the ecological resilience of the local bat community.
In closing (Chapter 5), we discuss the implications of our findings, highlighting the role of inselbergs as drivers of bat taxonomic and functional diversity, and facilitators of ecosystem resilience in the Afrotropics. These findings enhance our understanding of bat diversity and the mechanisms shaping it in a highly biodiverse region, currently facing increased pressure from anthropogenic changes. This body of work contributes to the limited research on how inselbergs influence faunal diversity, particularly in the Afrotropics. As biodiversity loss continues to accelerate, studies such as this provide critical insights into the factors that shape and sustain biodiversity. This research can be used to inform strategies to protect inselberg ecosystems, which not only contribute to local and regional biodiversity, but also serve as refuges and microrefugia for species.
Rights
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Persistent Identifier
https://archives.pdx.edu/ds/psu/43193
Recommended Citation
Grunwald, Amanda Lee, "Influence of Inselbergs on Bat Diversity in Afrotropical Ecosystems" (2025). Dissertations and Theses. Paper 6799.
