title: Tooth wear patterns in black rats (Rattus rattus) of Madagascar differ more in relation to human impact than to differences in natural habitats.
abstract: Dietary characteristics and environmental variables are important selective factors directing ecological diversification in rodents. On Madagascar, the introductions and spread of the commensal black rat (Rattus rattus) can be seen as example cases to study dietary niche occupation and dietary adaptation in an insular environment. We investigate how tooth wear as a measure of dietary adaptation of black rats differs between four distinct habitats (village, manioc fields, spiny forest, and rainforest) with different dietary resources. We use the 3D surface texture analysis (3DST, using 30 parameters according to ISO 25178) as a measure of dietary abrasiveness. 3DST is applied on the occlusal surface of the upper first molar of 37 black rat specimens. The rainforest sample displays less rough and less voluminous surface textures compared to the village samples as indicated by smaller values for height parameters (Sa, Sp, Sq), inverse areal material ratio (Smc), and volume parameters (Vm, Vmc, Vmp, Vv, and Vvc). We therefore rank sampling areas from highest to lowest abrasiveness (village>manioc fields/spiny forest>rainforest). The rats from villages and rainforest differ to such an extent that one could have interpreted them to belong to different species. This indicates a high degree of variability in terms of ingesta abrasiveness. Furthermore, the pronounced difference between rats from human habitations compared to rats from associated fields or natural vegetation is interpreted to clearly indicate shifts in dietary niche occupation in relation to human impact.
authors.affiliation: Center of Natural History (CeNak) University of Hamburg Hamburg Germany.
authors.forename: Daniela E
authors.initials: DE
authors.lastname: Winkler
authors.affiliation: Biocenter Grindel and Zoological Institute University of Hamburg Hamburg Germany; Département Biologie Animale Université d'Antananarivo Antananarivo Madagascar.
authors.forename: Tolona H
authors.initials: TH
authors.lastname: Andrianasolo
authors.affiliation: QIT Madagascar Minerals Fort Dauphin Madagascar.
authors.forename: Laza
authors.initials: L
authors.lastname: Andriamandimbiarisoa
authors.affiliation: Biocenter Grindel and Zoological Institute University of Hamburg Hamburg Germany.
authors.forename: Jörg U
authors.initials: JU
authors.lastname: Ganzhorn
authors.affiliation: Biocenter Grindel and Zoological Institute University of Hamburg Hamburg Germany.
authors.forename: S Jacques
authors.initials: SJ
authors.lastname: Rakotondranary
authors.affiliation: Center of Natural History (CeNak) University of Hamburg Hamburg Germany.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Kaiser
authors.affiliation: Center of Natural History (CeNak) University of Hamburg Hamburg Germany; Max Planck Weizmann Center for Integrative Archaeology and Anthropology Max Planck Institute for Evolutionary Anthropology Leipzig Germany.
authors.forename: Ellen
authors.initials: E
authors.lastname: Schulz-Kornas
keywords: Anthropogenic; Black rat; Madagascar; diet; surface texture; tooth wear