Dimensionality-Reduction in the Drosophila Wing as Revealed by Landmark-Free Measure-ments of Phenotype

TL;DR

This study introduces a mathematical method to analyze complex phenotypic variation in Drosophila wings, revealing a highly constrained, low-dimensional structure that simplifies understanding genotype-phenotype relationships.

Contribution

The paper presents a novel landmark-free, mathematical approach for describing phenotypic variation, demonstrating a single mode of variation in Drosophila wings.

Findings

Phenotypic variation is highly constrained in Drosophila wings.

A single integrated mode of variation explains most phenotypic differences.

The approach may be applicable to other genotype-phenotype studies.

Abstract

Organismal phenotypes emerge from a complex set of genotypic interactions. While technological advances in sequencing provide a quantitative description of an organism's genotype, characterization of an organism's physical phenotype lags far behind. Here, we relate genotype to the complex and multi-dimensional phenotype of an anatomical structure using the Drosophila wing as a model system. We develop a mathematical approach that enables a robust description of biologically salient phenotypic variation. Analysing natural phenotypic variation, and variation generated by weak perturbations in genetic and environmental conditions during development, we observe a highly constrained set of wing phenotypes. In a striking ex-ample of dimensionality reduction, the nature of varieties produced by the Drosophila developmental pro-gram is constrained to a single integrated mode of variation in the wing. Our strategy demonstrates the emergent simplicity manifest in the genotype-to-phenotype map in the Drosophila wing and may represent a general approach for interrogating a variety of genotype-phenotype relationships.