Skip to main content
SpringerLink
Log in

Geometric craniometric analysis of sexual dimorphism and ontogenetic variation: A case study based on two geographically disparate species, Aethomys ineptus from southern Africa and Arvicanthis niloticus from Sudan (Rodentia: Muridae)

  • Original Investigation
  • Published:
Mammalian Biology Aims and scope Submit manuscript

Abstract

Non-geographic morphometric variation, particularly at the level of sexual dimorphism and ontogenetic (age-related) variation, has been documented in rodents, and useful for establishing whether to analyse sexes separately or together, and for selecting adult specimens for subsequent data recording and analysis. However, such studies have largely been based on traditional morphometric analyses of linear measurements that mainly focus on overall size, rather than shape-related morphometric variation. Unit-free, landmark/outline-based geometric morphometric analyses are considered to offer a more appropriate tool for assessing shape-related morphometric variation. In this study, we used geometric cranial morphometric analysis to assess the nature and extent of sexual dimorphism and age variation within the Tete veld rat, Aethomys ineptus (Thomas and Wroughton, 1908) from southern Africa and the African Nile rat, Arvicanthis niloticus (Desmarest, 1822) from Sudan. The results obtained were in turn compared with previously published results based on independent geometric and traditional cranial morphometric data from the same sampled populations examined in the present study. While our geometric morphometric results detected statistically significant sexual dimorphism in cranial shape within Ar. niloticus only, previously published results based on traditional morphometric data failed to detect significant sexual dimorphism within this species. However, similar to previously published traditional morphometric data, our geometric morphometric results detected statistically significant age-related variation in cranial shape and size within both Ae. ineptus and Ar. niloticus, with individuals of age classes 5 and 6 being considered to represent adult specimens. Our results highlight the importance of carefully evaluating both size- and shape-related non-geographic morphometric variation prior to the analysis of geographic variation and the delineation of species. Erroneous conclusions of non-geographic variation may have implications in the interpretation of geographic and evolutionary processes that may be responsible for morphological differences at both the inter- and intra-specific levels.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Abdel-Rahman, E.H. 2005. Taxonomic status of Arvicanthis Lesson, 1842 from Sudan. Ph.D. Thesis, University of Kwa-Zulu Natal, Durban, South Africa.

    Google Scholar 

  • Atchley, W.R., Cowley, D.E., Vogl, C., Mclellan, T. 1992. Evolutionary divergence, shape change and genetic correlation structure in the rodent mandible. Syst. Biol. 41, 196–221.

    Article  Google Scholar 

  • Bailey, R.C., Byrnes, J. 1990. A new, old method for assessing measurement error in both univariate and multivariate morphometric studies. Syst. Zool. 39, 124–130.

    Article  Google Scholar 

  • Bookstein, F.L. 1986. Size and shape spaces for landmark data in two dimensions. Stat. Sci. 1, 181–222.

    Article  Google Scholar 

  • Bronson, F.H. 1989. Mammalian Reproductive Biology. University of Chicago Press, Chicago and London.

    Google Scholar 

  • Cesaroni, D., Matarazzo, P., Allegrucci, G., Sbordoni, V. 1997. Comparing patterns of geographic variation in cave crickets by combining geostatistic methods and Mantel tests. J. Biogeo 24, 419–431.

    Article  Google Scholar 

  • Chimimba, C.T., Dippenaar, N.J. 1994. Non-geographic variations in Aethomys chrysophilus (De Winton, 1897) and A. namaquensis (A. Smith, 1834) (Rodentia: Muridae) from Southern Africa. S. Afr. J. Zool. 29, 107–117.

    Google Scholar 

  • Clutton-Brock, T.H., Iason, G.R., Guinness, F.E. 1987. Sexual segregation and density-related changes in habitat use in male and female red deer (Cervus elaphus). J. Zool. (London) 211, 275–289.

    Article  Google Scholar 

  • Darwin, C.R. 1859. The Origins of Species by Means of Natural Selection. Murray, London.

    Google Scholar 

  • Darwin, C.R. 1874. The Descent of Man, and Selection in Relation to Sex, second ed. J. Murray, London.

    Book  Google Scholar 

  • Delany, M.J. 1975. The Rodents of Uganda. Trustees of the British Museum (Natural History), London.

    Google Scholar 

  • Fadda, C., Corti, M. 1998. Geographic variation of Arvicanthis (Rodentia, Muridae) in the Nile Valley. Z. Säugetierkd. 63, 104–113.

    Google Scholar 

  • Gould, S.J. 1966. Allometry and size in ontogeny and phylogeny. Biol. Rev. 41, 587–640.

    Article  CAS  PubMed  Google Scholar 

  • Hingst-Zaher, E., Marcus, L.F., Cerqueira, R. 2000. Morpholoigcal integration during ontogeny in Calomys tener (Sigmodontinae: Rodentia). Hystrix 11, 99–113.

    Google Scholar 

  • Hood, C.S. 2000. Geometric morphometric approaches to the sexual size dimorphism in mammals. Hystrix 11, 77–90.

    Google Scholar 

  • Krzanowski, W.J. 1988. Principles of Multivariate Analysis. Oxford University Press, Oxford.

    Google Scholar 

  • Lieberman, D.E., Krovitz, G.E., Yates, F.W., Devlin, M., St. Claire, M. 2004. Effects of food processing on masticatory strain and craniofacial growth in a retrognathic face. J. Hum. Evol. 46, 655–677.

    Article  PubMed  Google Scholar 

  • Linzey, A.V., Kesner, M.H., Chimimba, C.T., Newbery, C. 2003. Distribution of veld rat sibling species Aethomys chrysophilus and Aethomys ineptus (Rodentia: Muridae) in southern Africa. Afr. Zool. 38, 169–174.

    Article  Google Scholar 

  • Marcus, L.F. 1990. Traditional morphometrics. In: Rohlf, F.J., Bookstein, F.L. (Eds.), Proceedings of the Michigan Morphometric Workshop. University Michigan Museums, Ann Arbor, pp. 77–122.

    Google Scholar 

  • Mayr, E., Ashlock, P.D. 1991. Principles of Systematic Zoology, second ed. McGraw-Hill Inc., New York.

    Google Scholar 

  • Monteiro, L.R., Lessa, L.G., Abe, A.S. 1999. Ontogenic variation in skull shape of Trichomys apereoides (Rodentia: Echimyidae). J. Mammal. 80, 102–111.

    Article  Google Scholar 

  • Monteiro, L.R., Duarte, L.C., Dos Reis, S.F. 2003. Environmental correlates of geographical variation in skull and mandible shape of the punare rat Trichomys apereoides. J. Zool. (London) 261, 47–57.

    Article  Google Scholar 

  • Morris, P. 1972. A review of mammalian age determination methods. Mammal Rev. 2, 69–104.

    Article  Google Scholar 

  • Musser, G.D., Carleton, M.D. 2005. Family Muridae. In: Wilson, D.E., Reeder, D.M. (Eds.), Mammals Species of the World. A Taxonomic and Geographic Reference. Smithsonian Institution Press, Washington, DC, pp. 501–755.

    Google Scholar 

  • Olson, E.C., Miller, R.J. 1958. Morphological Integration. University of Chicago Press, Chicago.

    Google Scholar 

  • Patton, J.L., Rogers, M.A. 1983. Systematic implications of non-geographic variation in the spiny rat genus Proechimys (Echimyidae). Z. Säugetierkd. 48, 363–370.

    Google Scholar 

  • Piersma, T., Drent, J. 2003. Phenotypic flexibility and the evolution of organism design. Trends Ecol. Evol. 18, 228–233.

    Article  Google Scholar 

  • Polly, P.D. 2001. On morphological clocks and paleophylogeography: towards a timescale for Sorex hybrid zones. Genetica 112/113, 339–357.

    Article  PubMed  Google Scholar 

  • Pucek, Z., Lowe, V.P. 1975. Age criteria in small mammals. In: Golley, F.B., Petrusewicz, K., Ryszkowski, L. (Eds.), Small Mammals: Their Productivity and Population Dynamics. Cambridge University Press, Cambridge, pp. 55–72 (Chapter 3).

    Google Scholar 

  • Ricklefs, R.E., Finch, C.E. 1995. Patterns of aging. In: Aging: A Nature History. Scientific American Library, New York, pp. 1–17.

    Google Scholar 

  • Rohlf, F.J. 1996. NTSYS-pc. Numerical Taxonomy and Multivariate Analysis System. Exeter, Setaukel, New York.

    Google Scholar 

  • Rohlf, F.J. 2003. TpsSmall: Is Shape Variation Small. Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, New York.

    Google Scholar 

  • Rohlf, F.J., 2004. TPS Series. Department of Ecology and Evolution, State University of New York, Stony Brook, New York.

    Google Scholar 

  • Rohlf, F.J., Slice, D.E. 1990. Extensions of the Procrustes method for the optimal superimposition of landmarks. Syst. Zool. 39, 40–59.

    Article  Google Scholar 

  • Satoh, K., Iwaku, F. 2004. Internal architecture, origininsertion site, and mass of jaw muscles in Old World hamsters. J. Morphol. 260, 101–116.

    Article  PubMed  Google Scholar 

  • Schoener, T.W. 1967. The ecological significance of sexual dimorphism in size in the lizard Anolis conspersus. Sci. Stanford 155, 474–477.

    CAS  Google Scholar 

  • Schulte-Hostedde, A.I., Millar, J.S., Hickling, G.J. 2001. Sexual dimorphism in body composition of small mammals. Can. J. Zool. 79, 1016–1020.

    Article  Google Scholar 

  • Sneath, P.H., Sokal, R.R. 1973. Numerical Taxonomy. Freeman, San Francisco.

    Google Scholar 

  • Sokal, R.R., Rohlf, F.J. 1981. Biometry. W.H Freeman, New York.

    Google Scholar 

  • Taylor, P.J., Kumirai, A., Contrafatto, G. 2005. Species with fuzzy borders: the taxonomic status and species limits of saunders’vlei rat, Otomys saundersiae Roberts, 1929 (Rodentia: Muridae: Otomyini). Mammalia 69, 297–322.

    Article  Google Scholar 

  • Thorpe, R.S. 1976. Biometric analysis of geographic variation and racial affinities. Biol. Rev. 51, 407–452.

    Article  CAS  PubMed  Google Scholar 

  • Weckerly, F.W. 1998. Sexual-size dimorphism: influence of mass and mating system in the most dimorphic mammals. J. Mammal. 79, 33–52.

    Article  Google Scholar 

  • Wickens, A.P. 1998. The Causes of Aging. Harwood Academic Publishers, Amsterdam.

    Google Scholar 

  • Yamada, K., Kimmel, D.B. 1991. The effect of dietary consistency on bone mass and turnover in the growing rat mandible. Arch. Oral Biol. 36, 129–138.

    Article  CAS  PubMed  Google Scholar 

  • Yu, H.-T., Lin, Y.-S. 1999. Age, reproduction, and demography of the spiny rat (Muridae: Niviventer coxingi)in subtropical Central Taiwan. Zool. Stud. 38, 153–163.

    Google Scholar 

  • Zar, J.H. 1996. Biostatistical Analysis, fourth ed. Prentice-Hall Inc., Englewood Cliffs, NJ.

    Google Scholar 

  • Zelditch, M.L., Carmichael, A.C. 1989. Ontogenetic variation in patterns of developmental and functional integration in skulls of Sigmodon fulviventer. Evolution 43, 814–824.

    Article  PubMed  Google Scholar 

  • Zelditch, M.L., Bookstien, F.L., Lundrigan, B.L. 1992. Ontogeny of integrated skull growth in the cotton rat Sigmodon fulviventer. Evolution 46, 1164–1180.

    Article  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Mammal Research Institute (MRI), Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa

    Eitimad H. Abdel-Rahman & Christian T. Chimimba

  2. Durban Natural Science Museum, P.O. Box 4085, Durban, 4000, South Africa

    Peter J. Taylor

  3. School of Biological and Conservation Sciences, University of KwaZulu-Natal, P.O. Box 18091, Dalbridge, 4014, South Africa

    Giancarlo Contrafatto & Jennifer M. Lamb

  4. Department of Genetics, University of Pretoria, Pretoria, 0002, South Africa

    Paulette Bloomer

  5. DST-NRF Centre of Excellence for Invasion Biology (CIB), Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa

    Christian T. Chimimba

Authors
  1. Eitimad H. Abdel-Rahman
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Peter J. Taylor
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Giancarlo Contrafatto
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jennifer M. Lamb
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Paulette Bloomer
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Christian T. Chimimba
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Eitimad H. Abdel-Rahman.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Abdel-Rahman, E.H., Taylor, P.J., Contrafatto, G. et al. Geometric craniometric analysis of sexual dimorphism and ontogenetic variation: A case study based on two geographically disparate species, Aethomys ineptus from southern Africa and Arvicanthis niloticus from Sudan (Rodentia: Muridae). Mamm Biol 74, 361–373 (2009). https://doi.org/10.1016/j.mambio.2008.06.002

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1016/j.mambio.2008.06.002

Keywords

Search

Navigation