Publication Date


Document Type


First Advisor

Samonds, Karen E.

Second Advisor

Irwin, Mitchell T.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Biological Sciences


The accelerated transformation of Madagascar’s ecosystems is a direct result of habitat destruction which has devastating consequences for the viability of the island’s animals. This dissertation focuses on the critically endangered diademed sifaka, Propithecus diadema, living in the rainforests of Tsinjoarivo, Madagascar. Tsinjoarivo has been heavily impacted by slash and burn agriculture and transformed into isolated forest fragments. Previous research by Irwin and colleagues has demonstrated that the diet and group dynamics of Propithecus diadema differ between continuous and degraded forests, but whether fragmented landscapes provide tougher foods and lead to behavioral changes through increased tooth wear has not been comprehensively investigated, particularly with regards to reproductive success.

This research uses tooth wear as a means to interpret dental changes across age, sex, and habitat. Tooth molds from known-age individuals collected over a 15-year time span were laser scanned, and three-dimensional images were constructed for analysis using GIS software. Relief index, slope, and angularity were examined, and fragmented forest sifakas were found to possess increased dental wear.

Chewing efficiency was examined through leaf toughness, ingestion rate, and fecal particle size. Leaves in the fragmented forests show higher toughness, rates of food ingestion did not reveal an overall change in chewing to compensate for tooth wear, and feces from sifakas in fragmented forests had larger particle sizes in feces compared to their pristine forest counterparts. As for whether dental macrowear has an effect on reproductive success, infant deaths were compared to yearly rainfall totals, and the mother’s dental relief index, slope, and angularity; these factors did not appear to influence infant survival.

Although forest fragmentation has caused an accelerated loss of tooth wear in sifakas at Tsinjoarivo, they are still able to reproduce and wean infants into independent juveniles. This study indicates that the long-term viability of Propithecus diadema at Tsinjoarivo is stable and positive. However, continued monitoring of this population is critical; while they may be able adapt to current habitat modifications, the continuation of forest destruction could still severely impact their viability.


130 pages




Northern Illinois University

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