Full text in pdf format

Natural selection, morphologic divergence and phenotypic evolution in Proechimys dimidiatus (Rodentia: Echimyidae)

Leila M. Pessôa^I; Sérgio F. dos Reis^II

^IDepartamento de Zoologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, 21941 Rio de Janeiro, RJ, Brasil
^IIDepartamento de Parasitologia, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, 13081 Campinas, SP, Brasil. Send correspondence to S.F.R.

ABSTRACT

Models of evolutionry quantitative genetics were employed to study cranial morphologic differentiation in two populations of the echimyid rodent Proechimys dimidiatus from Tijuca and Teresópolis in the state of Rio de Janeiro. Under the assumption that the deterministic process of natural selection has acted to differentiate the two populations, the net selection gradient and minimum intensities of selection necessary to account for evolutionary divergence were calculated. The vector of selection coefficients indicated that some cranial traits evolved in the direction contrary to the force of selection. acting to increase mean values for cranial traits in the population from Tijuca. Minimum selective mortality per generation was low (10^-3) suggesting that weak selection can explain the observed

Keywords: Natural selection; Phenotypic evolution; Proechimys dimidiatus; Rodentia.

REFERENCES

Arnold, S.J. (1988). Quantitative genetics and selection in natural populations: Microevolution in vertebral numbers in the garter snakes Thamnophis elegans. Proceedings of the Second International Conference on Quantitative Genetics. (Weir, B.S., Eisen, E.J., Goodman, M.M. and Namkoong, G., eds.). Sinauer, Sunderland, pp. 619-636.

Bryant, E.H. and Meffert, L.M. (1990). Multivariate phenotypic differentiation among bottleneck lines of the housefly. Evolution 44: 660-668.

Bulmer, M.G. (1980). The Mathematical Theory of Quantitative Genetics. Oxford Univ. Press, Oxford. Caswell, H. (1989). Matrix Population Models. Sinauer, Sunderland.

Falconer, D.S. (1989). Introduction to Quantitative Genetics. 3rd Ed. Longman, London.

Grant, P.R (1986). Ecology and Evolution of Darwin's Finches. Princeton Univ. Press, Princeton.

Grant, B.R. and Grant, P.R. (1989). Evolutionary Dynamics of a Natural Population. Chicago Univ. Press, Chicago.

Harris, RJ. (1975). A Primer of Multivariate Statistics. Academic Press, New York.

Hartl, D.L. and Clark, A.G. (1989). Principles of Population Genetics. 2nd Ed. Sinauer, Sunderland.

Lande, R. (1976). Natural selection and random genetic drift in phenotypic evolution. Evolution 30: 314-334.

Lande, R (1979). Quantitative genetic analysis of multivariate evolution, applied to brain: body size allometry. Evolution 33: 402-416.

Lande, R. (1988). Quantitative genetics and evolutionary theory. Proceedings of the Second International Conference on Quantitative Genetics (Weir, B.S., Eisen, J., Goodman, M.M. and Namkoong, G., eds.). Sinauer, Sunderland, pp. 71-84.

Lande, R and Arnold, S.J. (1983). The measurement of selection on correlated characters. Evolution 37: 1210-1226.

Lofsvold, D. (1986). Quantitative genetics of morphological differentiation in Peromyscus. I. Tests of the homogeneity of genetic covariance structure among species and subspecies. Evolution 40: 559-573.

Lofsvold, D. (1988). Quantitative genetics of morphological differentiation in Peromyscus. II. Analysis of selection and drift. Evolution 42: 54-67.

Manly, B.F.J. (1985). The Statistics of Natural Selection. Chapman and Hall, London.

Morrison, D.F. (1976). Multivariate Statistical Methods. 2nd. Ed. McGraw-Hill, New York.

Patton, J.L. and Rogers, MA. (1983). Systematic implications of non-geographic variation in the spiny-rats genus Proechimys (Echimyidae). Z. Saeugetierkunde 48: 363-370.

Pessôa, L.M. and Reis, S.F. Geographic variation in Proechimys dimidiatus (Guenther) (Rodentia: Echimyidae). Zool. Anz. (in press).

Price, T.D., Grant, P.R. and Boag, P.T. (1984). Genetic changes in the morphological differentiation of Darwin's ground finches. In: Population Biology and Evolution (Worhmann, K. and Loeschke, V., eds). Springer Verlag, New York, pp. 49-66.

Reyment, RA. (1983). Phenotypic evolution in microfossils. Evol. Biol. 16: 209-255.

Schluter, D. (1984). Morphological and phylogenetic relations among the Darwin's finches. Evolution 38: 921-930.

Sokal, RR and Rohlf, F.J. (1981). Biometry. 2nd. Ed. W.H. Freeman, New York.