Species diversity within an ecosystem can be supported by favouring microhabitat specialisation. In complex habitats, like tropical rainforests, spatial and temporal segregation across microhabitats can expose species to distinct sensory realms. For many animals, visual systems serve as the primary conduit for perceiving biologically relevant sensory information, and the structural and functional variety of eyes and sensory brain regions reflects their critical role in diverse animal behaviours. However, little is known of their role in mediating niche segregation across subtle ecological scales, particularly in terrestrial environments. I explore the role of microhabitat partitioning in driving predictable patterns of adaptive visual system evolution within two diverse radiations of mimetic Neotropical butterfly, the Heliconius and Ithomiini. By taking a comparative approach, I investigate whether dual patterns of habitat divergence and convergence is manifested in the visual system at the perceptual, processing, and molecular level. I find extensive evidence of heritable, habitat-associated visual system variation, particularly for neural processing structures, hinting at the evolutionary lability of these systems to rapidly accommodate local adaptations to visual ecologies. My research also empirically demonstrates, for the first time, how variation in forest structure can give rise to distinct photic environments, highlighting the role of spectral variation as a major driver of adaptive community assemblage within a terrestrial forest radiation. In addition, evidence of visual morphological convergence offers a mechanistic insight into the evolvability of visual adaptations when confronted with similar ecological challenges, shedding light on their significance in promoting ecological diversification and speciation.
Patterns of visual adaptation in tropical mimetic butterflies
Wainwright, B. (Author). 5 Dec 2023
Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)