Signatures of convergence in Neotropical cichlid fish

Area of Science:

• Evolutionary biology
• Genetics
• Ecology

Background:

• Convergent evolution leads to similar phenotypes, suggesting predictable evolutionary paths.
• Cichlid fish radiations commonly exhibit convergent phenotypes and repeated morphological diversification axes.
• Adaptations in body patterns and trophic structures are key to cichlid diversification.

Purpose of the Study:

• To compare the morphological and genetic adaptations of two independently evolved Neotropical cichlid assemblages: the Mexican desert cichlid and the Nicaraguan Midas cichlid.
• To investigate shared and distinct axes of morphological differentiation in trophic structures and body shape.
• To explore the genetic underpinnings of convergent phenotypic adaptations.

Main Methods:

• Morphological and genetic analyses of Mexican desert cichlids and Nicaraguan Midas cichlids.
• Comparative analysis of trophic structures and body shape differentiation.
• Investigation of gene regulation associated with limnetic habitat adaptation.

Main Results:

• A common morphological axis of differentiation was identified in the trophic structures of both cichlid radiations.
• Two distinct axes of body shape differentiation were observed, resulting in alternative limnetic body patterns.
• Adaptation to limnetic habitats involved regulation of immune functions in Midas cichlids and morphogenesis/metabolic functions in desert cichlids.

Conclusions:

• Convergent phenotypic adaptations in cichlids can arise from independent evolutionary trajectories.
• Shared selective pressures and developmental constraints may drive similar morphological outcomes.
• Divergent gene regulation likely underlies convergent phenotypic adaptations in these cichlid radiations.