GULF OF GUINEA ISLANDS' BIODIVERSITY
NETWORK
asymmetry and morphometric patterns in the skull of Myonycteris
brachycephala (Mammalia: Megachiroptera), a fruit bat with an asymmetrical
dental formula.
Celia
López-González,1 Javier Juste,2,3 and R. E. Strauss4
1. CIIDIR Durango, COFAA-Instituto Politécnico Nacional, Sigma s/n,
Fracc. 20 de Noviembre II, Durango, Durango 34220, Mexico (celialg@prodigy.net.mx)
2. Estación Biológica de Doñana (CSIC), Sevilla, 41080, Spain
3. Departamento de Bioquímica y Biología Molecular IV. Facultad de
Veterinaria, Universidad
Complutense de Madrid, Madrid, Spain
4. Department of Biological Sciences, Texas Tech University, Lubbock, TX
79409-3131, USA
Abstract
Univariate and multivariate patterns of asymmetry and morphometric
variation in bilateral measurements were compared for a set of cranial
characters between the São Tomé Island fruit bat Myonycteris brachycephala, the only known mammal with an
asymmetrical dental formula, and two populations of a congener from the African
mainland, M. torquata.
We found no evidence of antisymmetry in any of the 73 characters
examined, neither significant differences in magnitude of multivariate
fluctuating asymmetry (FA) between populations within M.
torquata or between species. However,
directional asymmetry (DA) was more frequent in M.
brachycephala for characters of the rostrum.
Correlation structure of distances and multivariate FA were significantly
concordant within and between species. Correlation
structure for asymmetry and distance data was common to the two species
examined, which also share the same cranial structural pattern.
Results suggest that FA is an expression of phenotypic variation
resulting from the normal developmental processes that give rise to a
morphology. Correlation patterns
seem to be linked to a particular sequence of development rather than related to
phylogenetic affinities. There is
no evidence of developmental or genetic disruptions that may explain the shift
of the fruit bat developmental pathway from four- to three-toothed morphology,
and both patterns seem to be equally canalized.
Unlike FA, changes in development necessary to produce three-toothed
morphology seem to have affected the expression of DA.
Key words: fluctuating asymmetry, Myonycteris brachycephala, fruit bats, multivariate analysis, morphometrics, morphological patterns