Topic
Otomyini
About: Otomyini is a research topic. Over the lifetime, 3 publications have been published within this topic receiving 76 citations.
Papers
1 Jan 2004
TL;DR: Significant correlations were obtained between centroid size and both affine and non-affine components of skull shape in dorsal and ventral (but not mandibular) views and species from arid, semi-arid and Mountain Fynbos habitats were significantly smaller in size than remaining mesic-adapted species.
Abstract: Taylor, P.J., Kumirai, A., Contrafatto, G.-C. 2004. Geometric morphometric analysis of adaptive cranial evolution in southern African laminate-toothed rats (Family: Muridae, Tribe: Otomyini). Durban Museum Novitates 29: 110-122. Geometric morphometric analysis of cranial shape and size variation was carried out on laminate-toothed rats (Rodentia: Muridae: Otomyini) from southern Africa, to investigate adaptive evolution and morphometric relationships in eight species, and in cytotype-specific populations within one species, Otomys irroratus. Cranial size and shape variation between species could be explained by climate, habitat, phylogeny and burrowing behaviour. In dorsal shape, Otomys sloggetti (from montane and alpine habitats) and O. unisulcatus (from semi-arid habitats) were morphologically intermediate between arid-adapted (Paromys spp.) and mesic-adapted (O. irroratus, O. angoniensis, O. laminatus, O. tropicalis) lineages, consistent with an independently derived phylogeny. However, in ventral cranial shape and mandibular shape, Parotomys and Otomys were distinct from each other, and O. sloggetti (but not O. unisulcatus) was distinct from its congeners. Species from arid, semi-arid and Mountain Fynbos habitats were significantly smaller in size than remaining mesic-adapted species. Significant correlations were obtained between centroid size and both affine and non-affine components of skull shape in dorsal and ventral (but not mandibular) views. Subtle, but significant shape (but not size) differences were shown to distinguish the South African O. irroratus cytotypes (A, A1, A2, B and C) from the allopatric eastern Zimbabwe B cytotype population of O. irroratus.
19 citations
TL;DR: New cytogenetic, DNA sequence, and geometric morphometric data demonstrate the synonymy of O. saundersiae from Grahamstown (Eastern Cape, South Africa) under O. irroratus, and the validity of Otomys karoensis from the Fynbos Biome of the Western Cape.
Abstract: Chromosomal polytypy, morphological conservatism and absence of data have frustrated the taxonomic revision of two species of southern African-endemic laminate-toothed rats (Otomys irroratus and Otomys saundersiae s.l.). New cytogenetic (G-banding and fluorescence in situ hybridization), DNA sequence [cytochrome b (cyt b) gene] and geometric morphometric data demonstrate the synonymy of O. saundersiae from Grahamstown (Eastern Cape, South Africa) under O. irroratus, and the validity of Otomys karoensis from the Fynbos Biome of the Western Cape. Phenotypic dimorphism in pelage colour and cranial morphology in O. irroratus from the climatically unpredictable Albany Thicket (=Savanna) Biome of the Eastern Cape results from the retention of allometric paedomorphic traits in some adults (saundersiae morph) but not others. The same paedomorphic traits are associated with speciation and karyotypic and genetic differentiation in O. karoensis. Within O. irroratus, two phenotypically and genotypically (cyt b divergence=6.4%) divergent lineages correspond with the Fynbos/Albany Thicket and Grassland biomes. Incipient speciation in O. irroratus seems to be associated with ecology rather than karyotype.
TL;DR: A strict cladistic interpretation of the present data did not support the existence of two genera in the Otomyini, and the two species of Parotomys (whistling rats) should be transferred to Otomys, but poor statistical support was obtained for terminal relationships.
Abstract: Based on a cladistic analysis of 45 morphological (craniodental) and 46 binary allozyme characters, previous systematic treatments of the African murid tribe, Otomyini (laminate-toothed rats), are reviewed. Cladistic analysis of the craniodental data, involving eight outgroup taxa, confirmed the monophyly of the Otomyini, and suggested Pelomys to represent the sister genus of the Otomyini. Craniodental synapomorphies provided strong support for certain basal relationships among Otomyini rodents, reinforcing available palaeontological evidence. However, poor statistical (Bremer decay index) support was obtained for terminal relationships. The data presented revealed a ‘mesic clade’ of southern and eastern African species, with Otomys sloggetti basal to this group. The arid-adapted, southern Africa-endemic species, Parotomys littledalei, P. brantsii and O. unisulcatus, were all placed basal to the ‘mesic clade’, but did not form a separate ‘arid clade’, as suggested by earlier biochemical studies. Two allozyme synapomorphies supported the existence of the ‘mesic clade’, separate from arid-adapted southern African species. A strict cladistic interpretation of the present data did not support the existence of two genera in the tribe, and the two species of Parotomys (whistling rats) should be transferred to Otomys. At the species level, specific identity of O. lacustris and O. barbouri, distinct from O. anchietae, was supported by several autapomorphies, and O. tropicalis burtoni was shown to be included in O. angoniensis rather than O. tropicalis, extending the range of the former species into West Africa.
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Performance Metrics
| Year | Papers |
|---|---|
| 2009 | 1 |
| 2004 | 2 |