Eye development influences horn size but not patterning in horned beetles

Area of Science:

• Evolutionary Developmental Biology
• Genetics of Morphological Novelties
• Insect Morphology

Background:

• The origin of evolutionary novelties, such as beetle cephalic horns, is a key question in evolutionary developmental biology.
• Previous research suggests a link between gene regulatory networks of compound eye development and the formation and size of beetle horns.

Purpose of the Study:

• To investigate the role of genes involved in visual system development in the initiation, patterning, and size determination of cephalic horns.
• To understand the functional significance of eye patterning genes in the development of these evolutionary novelties across three horned beetle species.

Main Methods:

• Downregulation of canonical eye patterning genes in horned beetle species.
• Observation and analysis of the effects on compound eye formation, horn position, shape, and relative horn length.

Main Results:

• Downregulating eye patterning genes significantly reduced or eliminated compound eye formation.
• Horn position and shape remained unaltered despite the absence of compound eyes.
• A notable increase in relative horn length was observed when eye development genes were downregulated.

Conclusions:

• Genes central to compound eye development are not essential for the initiation or patterning of beetle cephalic horns.
• The visual system and cephalic horns exhibit a complex, potentially antagonistic, relationship in terms of size regulation.
• These findings provide new insights into the developmental mechanisms underlying the evolution of cephalic horns and other evolutionary novelties.