Heads up-Four Giraffa species have distinct cranial morphology

Giraffe (Giraffa spp.) are among the most unique extant mammals in terms of anatomy, phylogeny, and ecology. However, aspects of their evolution, ontogeny, and taxonomy are unresolved, retaining lingering questions that are pivotal for their conservation. We assembled the largest known dataset of Giraffa skulls (n = 515) to investigate patterns of cranial variability using 3D geometric morphometrics. The results show distinct sexual dimorphism and divergent ontogenetic trajectories of skull shape for the north clade (G. camelopardalis antiquorum, G. c. camelopardalis, G. c. peralta, and G. reticulata) and the south clade (G. giraffa angolensis, G. g. giraffa, G. tippelskirchi tippelskirchi, and G. t. thornicrofti) which was further supported statistically. Discriminant functions found statistically significant cranial shape differences between all four Giraffa species, and in some cases also between subspecies of the same species. Our 3D morphometric analysis shows that the four genetically distinct Giraffa spp. also have distinct cranial morphologies, largely addressable to features of display (ossicones). Our results highlight the importance of focusing future giraffe conservation efforts on each taxon to maintain their unique characteristics and biodiversity in the wild. Giraffe (Giraffa spp.) are among the most unique extant mammals in terms of anatomy, phylogeny, and ecology. However, aspects of their evolution, ontogeny, and taxonomy are unresolved, retaining lingering questions that are pivotal for their conservation. We assembled the largest known dataset of Giraffa skulls (n = 515) to investigate patterns of cranial variability using 3D geometric morphometrics. The results show distinct sexual dimorphism and divergent ontogenetic trajectories of skull shape for the north clade (G. camelopardalis antiquorum, G. c. camelopardalis, G. c. peralta, and G. reticulata) and the south clade (G. giraffa angolensis, G. g. giraffa, G. tippelskirchi tippelskirchi, and G. t. thornicrofti) which was further supported statistically. Discriminant functions found statistically significant cranial shape differences between all four Giraffa species, and in some cases also between subspecies of the same species. Our 3D morphometric analysis shows that the four genetically distinct Giraffa spp. also have distinct cranial morphologies, largely addressable to features of display (ossicones). Our results highlight the importance of focusing future giraffe conservation efforts on each taxon to maintain their unique characteristics and biodiversity in the wild.Copyright: © 2024 Kargopoulos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Giraffe Conservat Fdn
Leibniz Inst Evolut & Biodiversitatsforsch
Natl Museums Kenya
Wildlife Res & Training Inst
Senckenberg Biodivers & Climate Res Ctr
Universität Potsdam
Universität Kapstadt
Universidad Autonoma de Madrid
University College Dublin, National University of Ireland
Veterinärmedizinische Universität Wien
Czech University of Life Sciences Prague
University of Potsdam
Autonomous University of Madrid
Senckenberg Biodiversitat & Klima- Forschungszentrum (BiK-F)
University College Dublin
University of Cape Town
Leibniz Institut fur Evolutions und Biodiversitatsforschung