Biology subjects

MacIver, M. A.

Publications and source records attributed to MacIver, M. A..

4 recordsLinked to original sources

bioRxiv2026

Can a Tiny Brain Plan? Reconstructing a Predatory Detour inthe Jumping Spider Portia labiata

Planning is the process of evaluating alternative futures to predict outcomes and guide action. Evidence for this process exists in several vertebrates, but remains contested in in-vertebrates. Jumping spiders in the genus Portia show planning-like behavior in lab studies, but how this translates to the wild is unclear, where hunts of potentially lethal spider prey occur over durations of more than an hour in dense foliage. We present the first fully video-recorded wild hunt of any Portia species, with a 3D reconstruction of its forty-two minute long route to attack an orb-weaving spider. The reconstruction suggests P. labiata may have planned its approach, avoiding a route half as long but potentially more conspicuous to the prey's sensory systems.

animal behavior and cognition↗

bioRxiv2019

Sense organ control in moths to moles is a gamble on information

While animals track or search for targets, sensory organs make small unexplained movements on top of the primary task-related motions. While multiple theories for these movements exist--in that they support infotaxis, gain adaptation, spectral whitening, and high-pass filtering--predicted trajectories show poor fit to measured trajectories. We propose a new theory for these movements called energy-constrained proportional betting, where the probability of moving to a location is proportional to an expectation of how informative it will be balanced against the movements predicted energetic cost. Trajectories generated in this way show good agreement with measured target tracking trajectories of electric fish. Similarly good agreement was found across three published datasets on visual and olfactory tracking tasks in insects and mammals. Our theory unifies the metabolic cost of motion with information theory. It predicts sense organ movements in animals and can prescribe sensor motion for robots to enhance performance.

bioinformatics↗

bioRxiv2019

Intersection of motor volumes predicts the outcome of predator-prey interactions

The escape maneuvers of animals are key determinants of their survival. Consequently these maneuvers are under intense selection pressure. Current work indicates that a number of escape maneuver parameters contribute to survival including response latency, escape speed, and direction. This work has found that the relative importance of these parameters is context dependent, suggesting that interactions between escape maneuver parameters and the predatory context together determine the likelihood of escape success. However, it is unclear how escape maneuver parameters interact to contribute to escape success across different predatory contexts. To clarify these issues, we investigated the determinants of successful escape maneuvers by analyzing the responses of larval zebrafish to the attacks of dragonfly nymphs. We found that the strongest predictor of the outcome was the time needed for the nymph to reach the fishs initial position at the onset of the attack, measured from the time that the fish initiates its escape response. We show how this result is related to the intersection of the swept volume of the nymphs grasping organs with the volume containing all possible escape trajectories of the fish. By analyzing the intersection of these volumes, we compute the survival benefit of recruiting the Mauthner cell, a neuron in anamniotes devoted to producing escapes. We discuss how escape maneuver parameters interact in determining escape response. The intersection of motor volume approach provides a framework that unifies the influence of many escape maneuver parameters on the likelihood of survival.

animal behavior and cognition↗

bioRxiv2019

The shift to life on land selected for planning

Other than formerly land-based mammals such as whales and dolphins that have returned to an aquatic existence, it is uncontroversial that land animals have developed more elaborated cognitive abilities than aquatic animals. Yet there is no apparent a-priori reason for this to be the case. A key cognitive faculty is the ability to plan. Here we provide evidence that in a dynamic visually-guided behavior of crucial evolutionary importance, prey evading a predator, planning provides a significant advantage over habit-based action selection, but only on land. This advantage is dependent on the massive increase in visual range and spatial complexity that greeted the first vertebrates to view the world above the waterline 380 million years ago. Our results have implications for understanding the evolutionary basis of the limited ability of animals, including humans, to think ahead to meet slowly looming and distant threats, toward a neuroscience of sustainability.

neuroscience↗