Chitnis, S. S. | bioRxiv Science

bioRxiv2022

Maintaining a stable head direction representation in naturalistic visual environments

Many animals rely on a representation of head direction for flexible, goal-directed navigation. In insects, a compass-like head direction representation is maintained in a conserved brain region called the central complex. This head direction representation is updated by self-motion information and by tethering to sensory cues in the surroundings through a plasticity mechanism. However, under natural settings, some of these sensory cues may temporarily disappear--for example, when clouds hide the sun--and prominent landmarks at different distances from the insect may move across the animals field of view during translation, creating potential conflicts for a neural compass. We used two-photon calcium imaging in head-fixed Drosophila behaving in virtual reality to monitor the flys compass during navigation in immersive naturalistic environments with approachable local landmarks. We found that the flys compass remains stable even in these settings by tethering to available global cues, likely preserving the animals ability to perform compass-driven behaviors such as maintaining a constant heading.

neuroscience↗

bioRxiv2019

Sympatric wren-warblers partition acoustic signal space and song perch height

By evolving divergent acoustic signals, sympatric assemblages of animals may minimize potentially costly masking interference. Acoustic signal space may be multidimensional, with coexisting species also vocalizing from different regions of physical space. Here, we demonstrate acoustic signal space partitioning in four sympatric species of wren-warbler (Cisticolidae, Prinia), in an Indian dry deciduous scrub habitat. We find that the breeding songs of wren-warblers are divergent from each other in multivariate parameter space, with only minimal interspecific overlap. Partitioning of signal space exerts constraints on the intraspecific diversity of acoustic signals, and each species exhibits different strategies to overcome these constraints. Two species partition intraspecific signal space into multiple note types, whereas a third exhibits intraspecific variation in repetition rate, thus supporting song diversity within a constrained acoustic space. Finally, we find that the four species also partition song perch heights, thus exhibiting separation along multiple axes of acoustic signal space. We hypothesize that divergent song perch heights may be driven by competition for higher singing perches or other ecological factors rather than signal propagation. Acoustic signal partitioning along multiple axes may therefore, we propose, arise from a combination of diverse ecological processes.

animal behavior and cognition↗