Scientia Marina, 71(2): 383-394


Relative growth of the semi-terrestrial crab Pachygrapsus marmoratus: an information-theory approach


Nikos Protopapas, Stelios Katsanevakis, Maria Thessalou-Legaki, George Verriopoulos

Department of Zoology-Marine Biology, School of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens 15784, Greece



SUMMARY:  The patterns of allometric growth of the grapsid crab Pachygrapsus marmoratus were investigated with an information-theoretic approach. Such an approach is beneficial, more robust, and may reveal more information than the classical approaches (e.g. hypothesis testing). No differentiation in allometric growth was detected between right and left chelar propods, in both sexes. Significant sexual differentiation in the allometric growth of chelar propods, abdominal somites and telson was found.  It was shown that the allometry of chelar propodus width may be used to identify puberty in males, as there is a marked breakpoint at a carapace width of ~16.0 mm. For females, puberty was identified by the breakpoint in the allometry of third and fourth abdominal somites at a carapace width of ~ 16.5 mm. In many cases (e.g. in chelar propods of males, or in most abdominal somites and the telson in females) the classic allometric equation logY = loga + blogX had essentially no support and non-linear allometric models between the log-transformed morphometric characters should be used.



Keywords: AIC, allometry, breakpoint, crab, growth, information-theory