Foraging shifts and visual preadaptation in ecologically diverse bats

Area of Science:

• Evolutionary Biology
• Genomics
• Sensory Ecology

Background:

• Behavioral shifts often precede physical adaptations, with genetic factors like new mutations, standing diversity, or gene loss driving evolutionary change.
• Bats (superfamily Noctilionoidea) exhibit diverse ecological strategies, including varied echolocation, flight, and diets, with many possessing well-developed eyes despite echolocation capabilities.

Purpose of the Study:

• To investigate the role of molecular adaptations in eye-expressed genes during ecological niche shifts in Noctilionoidea bats.
• To determine whether positive selection on vision genes occurred before or after dietary specialization.

Main Methods:

• Analysis of positive and relaxed selection on eye-expressed genes.
• Comparative genomics across diverse bat lineages within Noctilionoidea.
• Tracing evolutionary timelines of selection pressures in relation to dietary shifts.

Main Results:

• Contrasting levels of positive selection were observed in vision genes, predating dietary shifts and linked to the origins of Noctilionoidea and Phyllostomidae.
• General plant-visiting did not correlate with significant molecular adaptation in vision genes.
• Subsequent shifts to nectarivory and frugivory showed evidence of positive selection in vision genes, particularly in nectar-feeding lineages and Stenodermatinae bats.

Conclusions:

• Noctilionoid bats were preadapted for exploiting new niches using visual cues due to ancestral genetic diversity in vision.
• Molecular adaptations in vision genes fine-tuned pre-existing visual capabilities for specialized nectarivory and frugivory.
• Sensory evolution, leveraging standing genetic variation, plays a crucial role in adaptive radiation alongside mutation-driven changes.