Biology subjects

Davis Rabosky, A. R.

Publications and source records attributed to Davis Rabosky, A. R..

3 recordsLinked to original sources

bioRxiv2021

Batch-Mask: An automated Mask R-CNN workflow to isolate non-standard biological specimens for color pattern analysis

O_LIEfficient comparisons of biological color patterns are critical for understanding the mechanisms by which organisms evolve in ecosystems, including sexual selection, predator-prey interactions, and thermoregulation. However, elongate or spiral-shaped organisms do not conform to the standard orientation and photographic techniques required for automated analysis. Currently, large-scale color analysis of elongate animals requires time-consuming manual landmarking, which reduces their representation in coloration research despite their ecological importance. C_LIO_LIWe present Batch-Mask: an automated and customizable workflow to facilitate the analysis of large photographic data sets of non-standard biological subjects. First, we present a user guide to run an open-source region-based convolutional neural network with fine-tuned weights for identifying and isolating a biological subject from a background (masking). Then, we demonstrate how to combine masking with existing manual visual analysis tools into a single streamlined, automated workflow for comparing color patterns across images. C_LIO_LIBatch-Mask was 60x faster than manual landmarking, produced masks that correctly identified 96% of all snake pixels, and produced pattern energy results that were not significantly different from the manually landmarked data set. C_LIO_LIThe fine-tuned weights for the masking neural network, user guide, and automated workflow substantially decrease the amount of time and attention required to quantitatively analyze non-standard biological subjects. By using these tools, biologists will be able to compare color, pattern, and shape differences in large data sets that include significant morphological variation in elongate body forms. This advance will be especially valuable for comparative analyses of natural history collections, and through automation can greatly expand the scale of space, time, or taxonomic breadth across which color variation can be quantitatively examined. C_LI

zoology↗

bioRxiv2019

Convergence and divergence in anti-predator displays: A novel approach to quantitative behavioural comparison in Neotropical snakes

Animals in nature use diverse strategies to evade or deter their predators, including many vivid behavioural displays only qualitatively described from field encounters with natural predators or humans. Within venomous snake mimicry, stereotyped anti-predator displays are suggested to be a critical component of the warning signal given by toxic models and thus under strong selection for independent convergence in mimetic species. However, no studies have systematically quantified variation in snake anti-predator displays across taxonomically broad clades to test how these behaviours evolve across species within a phylogenetic comparative methods framework. Here we describe a new, high-throughput approach for collecting and scoring snake anti-predator displays in the field that demonstrates both low observer bias and infinite extension across any species. Then, we show our methods utility in quantitatively comparing the behaviour of 20 highly-divergent snake species from the Amazonian lowlands of Peru. We found that a simple experimental setup varying simulated predator cues was very successful in eliciting anti-predator displays across species and that high-speed videography captured a greater diversity of behavioural responses than described in the literature. We also found that although different display components evolve at different rates with complicated patterns of covariance, there is clear evidence of evolutionary convergence in anti-predator displays among distantly related elapid coral snakes and their colubrid mimics. We conclude that our approach provides new opportunity for analyses of snake behaviour, kinematics, and the evolution of anti-predator signals more generally, especially macroevolutionary analyses across clades with similarly intractable behavioural diversity.

animal behavior and cognition↗

bioRxiv2019

A kinematic analysis of Micrurus coral snakes reveals unexpected variation in stereotyped anti-predator displays within a mimicry system

O_LIWarning signals in chemically defended organisms are critical components of predator-prey interactions, often requiring multiple coordinated display components for a signal to be effective. When threatened by a predator, venomous coral snakes (genus Micrurus) display a vigorous, non-locomotory thrashing behaviour that has been only qualitatively described. Given the high-contrast and often colourful banding patterns of these snakes, this thrashing display is hypothesized to be a key component of a complex aposematic signal under strong stabilizing selection across species in a mimicry system.\nC_LIO_LIBy experimentally testing snake response across simulated predator cues, we analysed variation in the presence and expression of a thrashing display across five species of South American coral snakes.\nC_LIO_LIAlthough the major features of the thrash display were conserved across species, we found significant variation in the propensity to perform a display at all, the duration of thrashing, and the curvature of snake bodies that was mediated by predator cue type, snake body size, and species identity. We also found an interaction between curve magnitude and body location that clearly shows which parts of the display vary most across individuals and species.\nC_LIO_LIOur results suggest that contrary to the assumption in the literature that all species and individuals perform the same display, a high degree of variation persists in thrashing behaviour exhibited by Micrurus coral snakes despite presumably strong selection to converge on a common signal. This quantitative behavioural characterization presents a new framework for analysing the non-locomotory motions displayed by snakes in a broader ecological context, especially for signalling systems with complex interaction across multiple modalities.\nC_LI

animal behavior and cognition↗