The macroevolution of size and complexity in insect male genitalia
- Published
- Accepted
- Subject Areas
- Biodiversity, Entomology, Evolutionary Studies, Zoology
- Keywords
- aedeagus, Coleoptera, directional selection, rates of evolution
- Copyright
- © 2016 Rudoy et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. The macroevolution of size and complexity in insect male genitalia. PeerJ Preprints 4:e1826v1 https://doi.org/10.7287/peerj.preprints.1826v1
Abstract
The evolution of insect male genitalia has received much attention, but there is still a lack of data on the macroevolutionary origin of its extraordinary variation. We used a calibrated molecular phylogeny of 71 of the 150 known species of the beetle genus Limnebius to study the evolution of the size and complexity of the male genitalia in its two subgenera, Bilimneus, with small species with simple genitalia, and Limnebius s.str., with a much larger variation in size and complexity. We reconstructed ancestral values of complexity (perimeter and fractal dimension of the aedeagus) and genital and body size with Bayesian methods. Complexity evolved more in agreement with a Brownian model, although with evidence of weak directional selection to a decrease or increase in complexity in the two subgenera respectively, as measured with an excess of branches with negative or positive change. On the contrary, aedeagus size, the variable with the highest rates of evolution, had a lower phylogenetic signal, without significant differences between the two subgenera in the average change of the individual branches of the tree. Aedeagus size also had a lower correlation with time and no evidence of directional selection. Rather than to directional selection, it thus seems that the higher diversity of the male genitalia in Limnebius s.str. is mostly due to the larger variance of the phenotypic change in the individual branches of the tree for all measured variables.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Specimens used
Specimens used, with locality, collector, voucher, species group according to Rudoy et al. (in press) and genbank accession numbers. Nf and Nm, number of females and males measured respectively; Ng, number of male genitalias measured; lf and lm, length of females and males respectively; stv.lf and stv.lm, standard deviation of lf and lm (for less than seven specimens the total range is given); lg, length of the male genitalia; stv.lg, standard deviation of lg.
Reconstructed values of the measured variables in all branches of the phylogeny
Reconstructed values of the measured variables in all branches of the phylogeny (see Figure S2 for the location of the branch numbers). The raw values of the initial and final nodes of each branch are given, together with the amount of phenotypic change, the absolute phenotypic change, and the change measured in darwins (x10^6). In pink, composite branch after deleting terminals with missing males. In yellow, reconstructed values.