Abstract
Semelparity and iteroparity are unevenly distributed among the families of the Paludicola and this implies that there have been taxonomic restrictions on life-history evolution. Species differ in their investments in reproduction and high levels can be related, causally, to reduced life-spans; i.e. semelparous species invest more in reproduction than iteroparous species. However, there does not appear to be any fundamental reason why the extent and timing of these investments should not be open to modification by natural selection.
A major morphological difference between the predominantly semelparous Dendrocoelidae and the predominantly iteroparous Dugesiidae and Planariidae is the presence of an anterior adhesive organ; dendrocoelids have one, but members of the other families do not. A plausible scenario can be formulated relating this structure, causally, to enhanced juvenile survivorship which, in turn, favors the semelparous life history.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Baguña, J., 1976a. Mitosis in the intact and regenerating planarian Dugesia mediterranea n.sp. I. Mitotic studies during growth, feeding and starvation. J. exp. Zool. 195: 53–55.
Baguña, J., 1967b. Mitosis in the intact and regenerating planarian Dugesia mediterranea n.sp. II. Mitotic studies during regeneration and a possible mechanism of blastema formation. J. exp. Zool. 195: 65–80.
Ball, I. R., 1974. A contribution to the phylogeny and biogeography of the freshwater triclads (Platyhelminthes: Turbellaria). In N. W. Riser & M. P. Morse (eds), Biology of the Turbellaria. McGraw-Hill, New York: 339–401.
Ball, I. R., 1981. The phyletic status of the Paludicola. Hydrobiologia 84: 7–12.
Beveridge, M., 1982. Taxonomy, environment and reproduction in freshwater triclads (Turbellaria: Tricladida). Int. J. Invert. Repr. 5: 107–113.
Brøndsted, H. V., 1969. Planarian regeneration. Pergamon Press, Oxford, New York, 276 pp.
Calow, P., 1978. Life cycles. Chapman & Hall, London, 164 pp.
Calow, P., 1979. The cost of reproduction — a physiological approach. Biol. Rev. 54: 23–40.
Calow, P., M. Beveridge & R. Sibly, 1979. Heads and Tails: adaptational aspects of asexual reproduction in freshwater triclads. Am. Zool. 19: 715–727.
Calow, P., A. W. Davidson & A. S. Woollhead, 1981. Life-cycle and feeding strategies of freshwater triclads: a synthesis. J. Zool., Lond. 193: 215–237.
Calow, P. & D. A. Read, 1981. Transepidermal uptake of the amino acid leucine by freshwater triclads. Comp. Biochem. Physiol. 69A: 443–448.
Calow, P. & R. Silby, 1983. Physiological trade-offs and the evolution of life cycles. Sci. Prog., Oxf. 68: 177–188.
Calow, P. & A. S. Woollhead, 1977. The relationship between ration, reproductive effort and the evolution of life-history strategies — some observations on freshwater triclads. J. Anim. Ecol. 46: 765–781.
Herrmann, J., 1982. Food, reproduction and population ecology of Dendrocoelum lacteum (Turbellaria) in South Sweden. Ph.D. thesis, University of Lund.
Jennings, J. B. & P. Calow, 1975. The relationship between high fecundity and the evolution of entoparasitism. Oecologia 21: 109–115.
Kirkwood, T. B. L., 1981. Repair and its evolution: survival versus reproduction. In C. R. Townsend & P. Calow (eds), Physiological ecology. Blackwell Scientific Publs. Oxford: 165–189.
Lange, C. S., 1968. A possible explanation in cellular terms of the physiological ageing of a planarian. Exp. Gerontol. 3: 219–229.
Lange, C. S., 1983. Stem cells in planarians. In C. S. Potten (ed.), Stem Cells. Churchill Livingstone, London: 28–66.
Martelly, I., C. Rey & A. Le Moigne, 1981. Planarian regeneration: DNA metabolism in adults. Int. J. Invert. Reproduct. 4: 107–121.
McCullagh, P. & J. A. Nelder, 1983. Generalised linear models. Chapman and Hall, London, 261 pp.
Mitchison, J. M., 1971. The biology of the cell cycle. Cambridge University Press, Cambridge, 313 pp.
Read, D. A. & P. Calow, 1984. Uptake and distribution of the amino acid leucine by freshwater triclads in different reproductive states. Comp. Biochem. Physiol. 77A: 231–234.
Reynoldson, T. B., 1979. A key to the British species of freshwater triclads (Turbellaria, Paludicola). F.B.A. (U.K.) Sci. Publ. No. 23, 2nd (revised) edition, 31 pp.
Reynoldson, T. B., 1983. The population biology of the Turbellaria with special reference to the freshwater triclads of the British Isles. Adv. Ecol. Res. 13: 235–326.
Ridley, M., 1983. The explanation of organic diversity. Clarendon Press, Oxford. 272 pp.
Sibly, R. & P. Calow, 1983. An integrated approach to life-cycle evolution using selective landscapes. J. theor. Biol., 102: 527–547.
Sibly, R. & P. Calow, 1984. Direct and absorption costing in the evolution of life cycles. J. theor. Biol. 111: 463–473.
Sokal, R. R. & F. J. Rohlf, 1969. Biometry. W. H. Freeman & Co., San Francisco, 776 pp.
Stearns, S. C., 1976. Life-history tactics: a review of the ideas. Q. Rev. Biol. 51: 3–47.
Stearns, S. C., 1984. The tension between adaptation and constraint in the evolution of reproductive patterns. Adv. Invert. Reprod. 3: 387–398.
Woollhead, A. S., 1983. Energy partitioning in semelparous and iteroparous triclads. J. Anim. Ecol. 52: 603–620.
Woollhead, A. S. & P. Calow, 1979. Energy-partitioning strategies during egg production in semelparous and iteroparous triclads. J. Anim. Ecol. 48: 491–499.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Calow, P., Read, D.A. Ontogenetic patterns and phylogenetic trends in freshwater flatworms (Tricladida); constraint or selection?. Hydrobiologia 132, 263–272 (1986). https://doi.org/10.1007/BF00046259
Issue Date:
DOI: https://doi.org/10.1007/BF00046259