Developmental bias in the evolution and plasticity of beetle horn shape
Creators: name: Rohner, Patrick T.
name: Hu, Yonggang
name: Moczek, Armin
Publisher: name: Zenodo
Year: 2022
Subjects: developmental bias
developmental plasticity
fluctuating asymmetry
Geometric Morphometrics
Integration
Onthophagus

description: The degree to which developmental systems bias the phenotypic effects of environmental and genetic variation, and how these biases affect evolution, is subject to much debate. Here, we assess whether developmental variability in horn shape aligns with the phenotypic effects of plasticity and evolutionary divergence, yielding three salient results. First, we find that most pathways previously shown to regulate horn length also affect shape. Second, we find that the phenotypic effects of manipulating divergent developmental pathways are correlated with each other as well as multivariate fluctuating asymmetry – a measure of developmental variability. Third, these effects further aligned with thermal plasticity, population differences, and macroevolutionary divergence between sister taxa and more distantly related species. Collectively, our results support the hypothesis that changes in horn shape —whether brought about by environmentally plastic responses, functional manipulations, or evolutionary divergences— converge along 'developmental lines of least resistance', i.e., are biased by the developmental system underpinning horn shape.
description: Raw data is supplied as .txt file. Code is supplied as an R script. The packages necessary to run the code and the respecive versions are indicated in the script.Funding provided by: John Templeton Foundation<br>Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000925<br>Award Number: 61369Funding provided by: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung<br>Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100001711<br>Award Number: P2ZHP3_184003Funding provided by: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung<br>Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100001711<br>Award Number: P400PB_199257Funding provided by: National Science Foundation<br>Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000001<br>Award Number: IOS 1256689Funding provided by: National Science Foundation<br>Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000001<br>Award Number: IOS 1901680
description: To investigate the evolution and development of horn shape, we used a two-dimensional geometric morphometric approach. For each of the data sets described below (fluctuating asymmetry, functional genetic manipulations, environmental plasticity, and evolutionary divergence), we took pictures of beetle head horns using a digital camera (Scion) mounted on a Leica MZ-16 stereomicroscope. The final data set included measurements for several wild-caught and laboratory-reared populations of <em>Onthophagus</em> <em>taurus</em>, one wild-caught population of the closely related <em>Onthophagus illyricus</em>, as well as laboratory-reared individuals of the more distantly related <em>Digitonthophagus</em> <em>gazella</em>. TpsDig2 was used to quantify horn shape using 4 landmarks and 26 semi-landmarks. The landmarks of all 1,044 specimens were subjected simultaneously to a Procrustes analysis in the R-package geomorph. The position of semi-landmarks was optimized by minimizing bending energy. Centroid size was extracted as a shape-independent measure of overall structural size. See Rohner et al. (doi: 10.1098/rspb.2022.1441) for furhter information.