Morphometric and Allozymic Congruence: Evolution in the Prawn Macrobrachium Rosenbergii (Decapoda: Palaemonidae)

Abstract

Morphometric and allozymic data were collected for eight populations of a palaemonid prawn, Macrobrachium rosenbergii (de Man), throughout Asia, north Australia, and parts of the western Pacific. For each data set, Fitch-Margoliash networks were constructed to estimate the patristric and cladistic relationships among these populations. Two measures of taxonomic congruence were calculated for the networks with varying results which are traced to inherent differences in the methods. Both measures indicated that the networks agreed in the divergence of the species into eastern and western subspecific groups along Wallace's Line, a zoogeographic discontinuity in Asia. These networks were correlated with paleogeologic and paleoclimatic theory to infer the species' expansion and evolution. The same paleotectonic factors resulting in the formation of Wallace's Line are thought to have caused the species' subspecific divergence. Climatic differences may promote selective forces which at different levels maintain Wallace's Line and the prawn's subspecific divergence.