Biology subjects

Narendra, A.

Publications and source records attributed to Narendra, A..

11 recordsLinked to original sources

bioRxiv2026

Deep conservation of head direction circuits in bees, ants and flies

To navigate, animal brains must continuously estimate the bodys heading in space and compare it with internal goals to guide movement. In the fruit fly Drosophila melanogaster a neural circuit in the central complex of the brain serves as an internal compass, exploiting a network architecture called a ring attractor1, 2. While this region is highly conserved and involved in navigation in many insects3, 4, it remains unclear whether the fly circuit represents a general blueprint for head direction computation, or whether different ecologies have driven distinct circuit solutions. Using synaptic-resolution circuit mapping, we identified homologous head direction networks in bees and ants and compared them to the fly circuit. We show that the insect head direction network is conserved across at least 300 million years of evolution. At the level of cell types and projection patterns, all studied species share a nearly identical neural layout, both qualitatively and quantitatively. At the synaptic level, however, the fly and bee circuits differed fundamentally. The distinct wiring principles of homologous neurons expose highly evolvable elements within this otherwise stable circuit. Using these differences in circuit architecture to constrain computational models, we show that both the bee and fly circuits can effectively function as ring attractors with similar, yet distinct, properties. These results demonstrate that complex neural circuits can remain stable over many hundreds of millions of years, while still offering access points for evolution to flexibly adjust neural computations to changing ecological demands, illustrating how evolution balances stability and flexibility in brain circuits.

neuroscience↗

bioRxiv2026

Tracking animal routes in 3D space through reconstructed habitats from dynamic videos

Contextualizing the movements of animals into their three-dimensional (3D) habitat contexts is still a major challenge for fields relying on animal tracking methods. This promises to change as Structure-from-Motion photogrammetry tools and techniques revolutionize image processing into the truly 3D spatial realm, by enabling reconstructions of habitat models from overlapping photographs. Combined with tracking data, these techniques would help elucidate drivers behind animal movements that have been previously masked by two-dimensional approaches. Unfortunately, tracking methods are often still impractical for use with understudied or non-model animals, especially those living underwater. In this paper, we describe a method for tracking the translational movements of animals into a photogrammetric habitat model. Our approach spans three general parts: (1) filming the navigation paths of wild animals by following individuals with small cameras (GoPros) on extendable sticks whilst SCUBA diving, (2) reconstructing a 3D spatial habitat model from separate footage, and (3) manually plotting the 3D trajectories of animals into the habitat model. We used one popular commercial software for photogrammetric reconstruction, trajectory plotting, and measurement of trajectories, after which the plots can be exported in a variety of formats for further analyses. Straightforward and flexible methodologies such as this stand to encourage more fieldwork concerning animals that live in structurally complex habitats, or animals that are underrepresented in movement or navigation research. We expect that this approach can be adapted to study many aquatic or terrestrial animals in different habitats, and at various scales.

ecology↗

bioRxiv2025

Caste- and Sex-Specific Differential Investment in Brain Regions of Australian Ants

Even within a single species, closely related individuals exhibit distinct lifestyles that demand different information processing requirements. Worker ants are ambulatory and handle tasks like colony maintenance and foraging, while winged reproductive castes focus on mating and colony founding. Here, we compare the volumes of functionally distinct brain regions across alate males, alate females, and workers in two species of ants native to Australia, Myrmecia midas and Rhytidoponera metallica, to assess adaptations to behavioural, ecological, and locomotor demands. Female castes in both species had larger brains with pronounced mushroom bodies, supporting their broader behavioural repertoire and navigational tasks. In comparison, males exhibited smaller brains but enlarged optic lobes and central complexes, highlighting the significance of vision and orientation in mate searching. Species-specific patterns were also noted: R. metallica individuals consistently had larger antennal lobes and smaller optic lobes across castes, indicating a reliance on olfactory cues. However, the mushroom bodies remained comparatively similar. These findings demonstrate how caste- and species-specific sensory demands shape neural architecture and serve as a basis for understanding the interplay between brain structure and function.

zoology↗

bioRxiv2024

Visual physiology of Australian stingless bees

Stingless bees engage in a range of visually guided behaviours that require relatively high spatial resolution and contrast sensitivity. Although the eyes of honeybees, bumblebees, carpenter bees, and sweat bees have been studied extensively, there is limited knowledge of stingless bees. Here, we studied two sympatric Australian species, Tetragonula carbonaria and Austroplebeia australis, which are important crop pollinators. The bigger A. australis had more and larger ommatidial facets compared to T. carbonaria. Using pattern electrophysiology, we showed that A. australis had higher contrast sensitivity (13.07) compared to T. carbonaria (5.99), but their spatial resolving power did not differ (0.53 cycles deg-1). We discuss these differences in visual physiology in the context of the distinct foraging behaviours of the two species.

evolutionary biology↗

bioRxiv2024

Sexual Dimorphism in Jump Kinematics and Choreography in Peacock Spiders

Jumping requires a rapid release of energy to propel an animal. Terrestrial animals achieve this by relying on the power generated by muscles, or by storing and rapidly releasing elastic energy. Jumping spiders rely on hydraulic pressure and muscular action to propel their jump. Though males and females of jumping spiders vary in size, sex-specific differences in jumping have never been studied. We investigated sexual dimorphism in the jump kinematics of an Australian Peacock spider, Maratus splendens. We recorded locomotory jumps in males and females using high-speed videography (5000 frames per second). We determined the centre of mass of the animals using {micro}CT and tracked its displacement during a jump. We found that although females weighed more than twice as much as males, both had similar accelerations and take-off velocities. Males had shorter jump take-off duration, steeper take-off angle and experienced higher g-force compared to the females. We examine the jump choreography of male and female spiders and explore the factors behind the differences in their jump kinematics.

animal behavior and cognition↗

bioRxiv2024

Before the brink: sublethal impacts of climate change on stingless bee flight performance

AimWe aimed to understand the sublethal impacts of climate change on native bee ecology. We evaluated how flight performance, a key trait for predator escape, dispersal, and pollination, is impacted by temperature. We aimed to understand how species geographic ranges shape species thermal performance curves (TPCs) and determine species vulnerability to further warming. LocationAustralia Time periodPresent Major taxa studiedStingless bees MethodsWe tested the flight speed and acceleration of two species of stingless bees, Austroplebeia australis and Tetragonula carbonaria at seven test temperatures. We examined how the climate experienced by species throughout their ranges shapes their TPCs. Inferences were made on how sublethal increases in temperature will likely impact key ecological activities associated with flight by estimating the proportion of species geographic ranges that experience temperatures that exceed their thermal optima. ResultsSpecies TPCs reflected the thermal environments they inhabit. A. australis, which experiences greater thermal variation and hotter temperatures throughout their range, had a broader TPC and higher thermal optima. However, A. australis also had faster flight performance than T. carbonaria, rejecting the jack-of-all-trades master-of-none hypothesis. Further increases in temperature will reduce flight performance of T. carbonaria at a faster rate (due to their narrower TPCs) than A. australis, however, a larger proportion of the A. australis range is currently exposed to temperatures above their thermal optima. Main conclusionsClimates will impact species ecology before they reach their lethal limits. Our study supports the idea that species fundamental niche breadths are linked to their geographic ranges, but that trade-offs are not associated with flight performance and ability to perform across a broad range of temperatures. When assessing vulnerability to climate change, it is important to consider how temperature impacts species traits, but also the climates that species experience throughout their unique geographic ranges.

physiology↗

bioRxiv2024

A new leaf sensing organ in a predatory insect group, the praying mantises (Mantodea)

Animals sensory systems enable them to navigate and interact with their environments. Adaptive specializations of these systems can generate novel structures or organs that support highly unique niche adaptations. We report the discovery of a novel sensory organ in a group of praying mantises (Insecta, Mantodea, Nanomantoidea), which have an unusual "leaf-planking" ecomorphic life strategy, laying against the undersides of broadleaf vegetation. Histology, scanning electron microscopy, and x-ray computed tomography all support the novelty of this distinct morphology while electrophysiology reveals that the sensory organ, herein designated the gustifolium organ, detects plant volatiles. The location of the gustifolium organon the ventral thoracic surface of these mantises appears to facilitate the chemical detection of the leaves on which it resides. The gustifolium is a novel plant volatile-detecting sensory structure in an obligate predatory insect, directly linked to a newly-identified, highly-adapted life strategy.

zoology↗

bioRxiv2023

Moonlight Polarisation Pattern Guides Nocturnal Bull Ants Home

For the first time in any animal, we show that nocturnal bull ants use the exceedingly dim polarisation pattern produced by the moon for overnight navigation. The sun or moon can provide directional information via their position; however, they can often be obstructed by clouds, canopy or the horizon. Despite being hidden, these bodies can still provide compass information through the polarised light pattern they produce/reflect. Sunlight produces polarised light patterns across the overhead sky as it enters the atmosphere, and solar polarised light is a well-known compass cue for navigating animals. Moonlight produces an analogous pattern, albeit a million times dimmer than sunlight. Here we show evidence that polarised moonlight forms part of the celestial compass of navigating nocturnal ants. Nocturnal bull ants leave their nest at twilight and rely heavily on the overhead solar polarisation pattern to navigate. Yet many foragers return home overnight when the sun cannot guide them. We demonstrate that these bull ants use polarised moonlight to navigate home during the night, by rotating the overhead polarisation pattern above homing ants, who alter their headings in response. Furthermore, these ants can detect this cue throughout the lunar month, even under crescent moons, when polarised light levels are at their lowest. Finally, we show long-term incorporation of this moonlight pattern into the ants path integration system throughout the night for homing, as polarised sunlight is incorporated throughout the day.

animal behavior and cognition↗

bioRxiv2023

Parallel and divergent morphological adaptations underlying the evolution of jumping ability in ants

Jumping is a rapid locomotory mode widespread in terrestrial organisms. However, it is a rare specialization in ants. Forward jumping has been reported within four distantly related ant genera: Gigantiops, Harpegnathos, Myrmecia, and Odontomachus. The temporal engagement of legs/body parts during jump, however, varies across these genera. It is unknown what morphological adaptations underlie such behaviors, and whether jumping in ants is solely driven directly by muscle contraction or additionally relies on elastic recoil mechanism. We investigate the morphological adaptations for jumping behavior by comparing differences in the locomotory musculature between jumping and non-jumping relatives using x-ray micro- CT and 3D morphometrics. We found that the size-specific volumes of the trochanter depressor muscle (scm6) of the middle and hind legs are 3-5 times larger in jumping ants, and that one coxal remotor muscle (scm2) is reduced in volume in the middle and/or hind legs. Notably, the enlargement in the volume of other muscle groups is directly linked to the legs or body parts engaged during the jump. Furthermore, a direct comparison of the muscle architecture revealed two significant differences between in jumping versus non-jumping ants: First, the relative Physiological Cross-Sectional Area (PCSA) of the trochanter depressor muscles of all three legs were larger in jumping ants, except in the front legs of O. rixosus and M. nigrocincta; second, the relative muscle fiber length was shorter in jumping ants compared to non-jumping counterparts, except in the front legs of O. rixosus and M. nigrocincta. This suggests that the difference in relative muscle volume in jumping ants is largely invested in the area (PCSA), and not in fiber length. There was no clear difference in the pennation angle between jumping and non-jumping ants. However, the length of hind legs relative to body length was longer in jumping ants. Based on direct comparison of the observed vs. possible work and power output during jumps, we surmise that direct muscle contractions suffice to explain jumping performance, in two species, but elastic recoil is likely important in one. We suggest that increased investment in jumping-relevant musculature is a primary morphological adaptation that separates jumping from non-jumping ants. These results elucidate the common and idiosyncratic morphological changes underlying this rare adaptation in ants.

evolutionary biology↗

bioRxiv2022

Deconstructing a visual signal: the role of motion and colour in predator deterrence

Visual animal communication, whether to the same species or to other species, is largely conducted through dynamic and colourful signals. For a signal to be effective, the signaller must capture and retain the attention of the receiver. Signal efficacy is also dependent on the sensory limitations of the receiver. However, most signalling studies consider movement and colour separately, resulting in a partial understanding of the signal in question. We explored the structure and function of predator-prey signalling in the jumping spider-tephritid fly system, where the prey performs a wing waving display that deters an attack from the predator. Using a custom-built spider retinal tracker combined with visual modelling, and behavioural assays, we studied the effect of fly wing movement and colour on the jumping spiders visual system. We show that jumping spiders track their prey less effectively during wing display and this can be attributed to a series of fluctuations in chromatic and achromatic contrasts arising from the wing movements. These results suggest that displaying flies deter spider attacks by manipulating the movement biases of the spiders visual system. Our results emphasise the importance of receiver attention on the evolution of interspecific communication.

animal behavior and cognition↗

bioRxiv2021

Ocellar spatial vision in Myrmecia ants

In addition to the compound eyes insects possess simple eyes known as ocelli. Input from the ocelli modulates optomotor responses, flight-time initiation and phototactic responses, behaviours that are predominantly mediated by the compound eyes. In this study, using pattern electroretinography (pERG), we investigated the contribution of the compound eyes to ocellar spatial vision in the diurnal Australian bull ant, Myrmecia tarsata by measuring the contrast sensitivity and spatial resolving power of the ocellar second-order neurons under various occlusion conditions. Furthermore, in four species of Myrmecia ants active at different times of the day and in European honeybee, Apis mellifera, we characterized the ocellar visual properties when both visual systems were available. Among the ants, we found that the time of activity had no significant effect on ocellar spatial vision. Comparing day-active ants and the honeybee we did not find any significant effect of locomotion on ocellar spatial vision. In M. tarsata, when the compound eyes were occluded, the amplitude of the pERG signal from the ocelli reduced by three times compared to conditions when the compound eyes were available. The signals from the compound eyes maintained the maximum contrast sensitivity of the ocelli as 13 (7.7%), and the spatial resolving power as 0.29 cpd. We conclude that ocellar spatial vison improves significantly with input from the compound eyes, with a noticeably larger improvement in contrast sensitivity than in spatial resolving power.

evolutionary biology↗