Discussion 3 synopsis
Shamra Byrne, Jeff Jewell, Ben Garner, Huy Tran and Lisa Chen
The first section of this synopsis talks about the paper by Michael Whiting discussing the
reevolution of wings in stick insects and was led by Shamra Byrne and Jeff Jewell.
It had previously been hypothesized that, due to its unlikely nature, stick insects could not revert
from a flightless to a volant form.
It was said that because current stick insects are winged, their common
ancestor must have had wing function because otherwise, in order to accommodate flight, the
contemporaries would have had to have developed incredibly complex interactions between multiple
In addition, if throughout evolution stick insects reverted from a flightless to volant form and
back again, the genes for wing function, when not in use, would have accumulated so many mutations
that the ability to regain wing function would be lost.
However, in this article, Whiting, Bradler, and
Maxwell attempt to illustrate through the construction of a stick insect molecular phylogeny and
maximum parsimony that it was indeed possible that ancestral stick insects were wingless and that wings
They suggest that the basic framework for the wing has been conserved from
ancestral stick insects and is simply re-expressed upon the recovery of wings.
Because of this
conservation, it is possible for stick insects to gain wings, lose them, and even gain them again through
the course of evolution.
Because it is difficult to classify stick insects into distinct phylogenetic groups, current
classification is based mainly off of morphological traits.
For instance, most stick insects are either large
terrestrial or arboreal insects that exhibit extreme morphological and behavioral crypsis, meaning that
they have an uncanny ability to blend in with their surroundings.
In addition, they are characterized by
several distinctive traits such as prothoracic repellant glands, male vomer, and the absence of
mitochondria in spermatozoa.
Whiting et al had a tough task ahead of them.
The classification of Family Phasmotodea into
phylogenetic groups was by no means a small task due to the reasons listed above.
In order to try and
accurately classify these insects his lab had to use genetic markers to help link groups phylogenetically.
They chose to use ribosomal DNA as a genetic marker because it is found in all cells, has relatively easy
access due a conserved flanking region which allows use of universal primers and has a repetitive
arrangement allowing for PCR.
Historically only a portion of the ribosomal DNA was used; the 18s
However, contrary to initial high expectations, it was found that the 18s region cannot resolve
nodes at all taxonomic levels therefore multi gene analysis is required in order to more accurately place
So, the lab also used the 28s region of ribosomal DNA and a portion of histone 3.
Once the genetic data was collected it was entered into a computer program to try and create a