Predicting Ancestral Segmentation Phenotypes from Drosophila to Anopheles Using In Silico Evolution

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Computational Biology

Background:

• Inferring ancestral gene regulatory networks is difficult because regulatory DNA evolves rapidly.
• Gene homology is typically inferred using molecular evolution, but this is often impossible for regulatory DNA.
• The expression patterns of gap genes have changed between Drosophila (fly) and Anopheles (mosquito).

Purpose of the Study:

• To compute the most parsimonious evolutionary path in regulatory space for anterior-posterior patterning between two Dipterian species.
• To investigate the evolutionary trajectory of the eve gene, a target of gap genes, which has remained invariant despite changes in its upstream regulators.

Main Methods:

• Utilized in silico evolution to model the evolutionary changes in gene regulatory networks.
• Compared the expression patterns of gap genes and their target eve gene between Drosophila and Anopheles.
• Mapped the evolutionary pathway of the eve gene, including placing Clogmia within this pathway.

Main Results:

• The study predicts the disappearance of stripe 5 in the fly and the emergence of a new posterior stripe in the mosquito.
• Identified homologous eve stripe modules: modules 3+7 and 4+6 in the fly are homologous to 3+6 and 4+5 in the mosquito.
• Clogmia shares the same homologies as the mosquito, indicating its position on the inferred evolutionary pathway.

Conclusions:

• The evolutionary model successfully traces the regulatory changes of the eve gene between Drosophila and Anopheles.
• The findings suggest a dynamic mechanism was employed by the ancestral Dipterian to regulate pair-rule genes in relation to eve.
• This study provides insights into the evolution of gene regulatory networks and highlights the utility of in silico evolution for studying conserved developmental processes.