How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
- Stanford University, United States
- Eindhoven University of Technology, Netherlands
- Sorama, Netherlands
Abstract
How hummingbirds hum is not fully understood, but its biophysical origin is encoded in the acoustic nearfield. Hence, we studied six freely hovering Anna's hummingbirds, performing acoustic nearfield holography using a 2176 microphone array in vivo, while also directly measuring the 3D aerodynamic forces using a new aerodynamic force platform. We corroborate the acoustic measurements by developing an idealized acoustic model that integrates the aerodynamic forces with wing kinematics, which shows how the timbre of the hummingbird's hum arises from the oscillating lift and drag forces on each wing. Comparing birds and insects, we find that the characteristic humming timbre and radiated power of their flapping wings originates from the higher harmonics in the aerodynamic forces that support their bodyweight. Our model analysis across insects and birds shows that allometric deviation makes larger birds quieter and elongated flies louder, while also clarifying complex bioacoustic behavior.
Data availability
All data needed to evaluate the conclusions presented in the paper are available on Dryad, https://doi.org/10.5061/dryad.73n5tb2vs.
-
Data from: How Oscillating Aerodynamic Forces Explain the Timbre of the Hummingbird's Hum and Other Animals in Flapping FlightDryad Digital Repository, 10.5061/dryad.73n5tb2vs.
Article and author information
Author details
Funding
National Science Foundation (Faculty Early Career Development (CAREER) Award,1552419)
- David Lentink
National Science Foundation (Graduate Research Fellowship)
- Ben J Hightower
Stanford University (Stanford Graduate Fellowship)
- Ben J Hightower
Netherlands Organisation for Scientific Research (Research Program ZERO (P15-06))
- Patrick W A Wijnings
Stanford University (Stanford Graduate Fellowship)
- Diana D Chin
National Defense Science and Engineering Graduate (Graduate Fellowship)
- Diana D Chin
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All bird training and experimental procedures were approved by Stanford's Administrative Panel on Laboratory Animal Care (APLAC-31426).
Copyright
© 2021, Hightower et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 3,706
- views
-
- 386
- downloads
-
- 6
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
eLife 10:e63107.
https://doi.org/10.7554/eLife.63107
Further reading
-
Specific aerodynamic forces created by its wings explain the hum of the Hummingbird
-
- Evolutionary Biology
- Genetics and Genomics
Expression quantitative trait loci (eQTLs) provide a key bridge between noncoding DNA sequence variants and organismal traits. The effects of eQTLs can differ among tissues, cell types, and cellular states, but these differences are obscured by gene expression measurements in bulk populations. We developed a one-pot approach to map eQTLs in Saccharomyces cerevisiae by single-cell RNA sequencing (scRNA-seq) and applied it to over 100,000 single cells from three crosses. We used scRNA-seq data to genotype each cell, measure gene expression, and classify the cells by cell-cycle stage. We mapped thousands of local and distant eQTLs and identified interactions between eQTL effects and cell-cycle stages. We took advantage of single-cell expression information to identify hundreds of genes with allele-specific effects on expression noise. We used cell-cycle stage classification to map 20 loci that influence cell-cycle progression. One of these loci influenced the expression of genes involved in the mating response. We showed that the effects of this locus arise from a common variant (W82R) in the gene GPA1, which encodes a signaling protein that negatively regulates the mating pathway. The 82R allele increases mating efficiency at the cost of slower cell-cycle progression and is associated with a higher rate of outcrossing in nature. Our results provide a more granular picture of the effects of genetic variants on gene expression and downstream traits.
