As molecular phylogenies improve we will be able to clarify the temporal relationship between cladogenesis and morphological diversification [32] and explore in more detail the evolution of morphological covariance structure during adaptive radiation [33].
Although these studies indicate that mouthbrooding has considerable influence on craniofacial diversification, studies that address the link between mouthbrooding and morphological diversification while considering the effect of shared ancestry are lacking.
In the case of some adaptive radiations where there is repeated morphological diversification, this divergence in morphology may also be convergent (termed "replicate adaptive radiation", [ 5]).
Their bright colours and rampant morphological diversification of geographic races within species and between species have led them being highly prized by collectors, and a good representation of specimens is found in museums and private hands worldwide.
This suggests that morphological diversification is driven by natural selection pushing morphologies toward more diverse and extreme forms (Mayr, 1984).
However, the data we obtained show no distinct correlations (Table 3), suggesting that the morphological diversification might have occurred late after their maternal divergences, especially between the two deep lineages.
HOX genes encode conserved transcription factors that control the morphological diversification along the anteroposterior body axis.
Applying these complimentary analyses to future comparative studies will improve our understanding of the relationship between morphological convergence and non-convergence, and the roles of contingency, chance and determinism in driving morphological diversification.
Patterns of morphological diversification among the shape elements appear to covary similarly in the three assemblages.
