The role of growth stop as a morphogenetic factor in Mastomys natalensis (Rodentia: Muridae)

The present study investigated growth patterns under three different environmental conditions in a single population of the rodent Mastomys natalensis (Rodentia, Muridae) in Morogoro, Tanzania. The study aimed to test whether and how post-weaning ontogenetic processes are affected by different environmental conditions. Morogoro is characterized by a bimodal rainfall pattern, with unreliable peaks occurring in November/December of some years and reliable ones in February to May. We recognized three different generation types. In the first one, the alpha generation, growth occurred during the dry second half of the year in years when the November/December rains were very poor. The second group (beta generation) grew under conditions when these rains were abundant. Finally, the gamma generation, consisted of animals that were born in the middle of the rainy season in years when there was a continuity between both rainfall peaks. Analyses of size and shape following both Huxley-Jolicoeur and Gould-Mosimann approaches revealed that the three groups differ significantly both in size and shape. In both cases, the importance of the environment in assessing growth trajectories during post-natal ontogenetic processes is apparent. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 791-800.