The Roach Brain Lab
for studying biodiversity through molecular systematics
Organismal Biology
Phylogenetics
I approach questions about biological phenomena by focusing them on a specific organism (in my case, Blattodea). In an informal survey of biologists at a large research university (see image at left; N=28) I found that biologists unanimously agreed that organismal biology is worth studying. However, there is a disconnect between certain types of biologists and the conditions under which they believe this kind of research is important. In my opinion, the rapid loss of global biodiversity due to humans puts a huge importance on learning about organisms before they go extinct. My research typically attempts to address broad research questions using an organismal model system. Yet, narrow research questions (i.e. alpha taxonomy) are also important because of impending biodiversity loss. Careful consideration of how to effectively communicate the greater importance of both kinds of research (to all kinds of biologists and to non-biologists) is necessary for the future of organismal biology, and for the future of biodiversity in general.
Phylogeny of Blattodea
Blattodea is a clade of hemimetabolous insects closely related to mantises. The group Blattodea (or Blattaria) was traditionally thought of as synonymous with cockroaches, but recent work has shown confidently that Blattodea also contains termites, who evolved from a cockroach ancestor. Thus, eusociality evolved once within Blattodea and there are multiple independent origins of subsociality, wood feeding, burrowing, and various types of parental care.
Yet, there is much more that we don't know about their relationships. The phylogeny on the left shows our uncertainty in the relationships of the major lineages of Blattodea (unresolved clades are shown in polytomies with dashed lines). Much of my work in molecular systematics aims to resolve this phylogeny. My recent publications infer the deep relationships using transcriptomic data, and discuss support for this phylogeny in studies using only 6 genes.
Phylogeny of Blaberoidea
Blaberoidea is an ancient lineage of cockroaches with 3500 described species. This is very diverse for a Polyneopteran insect (only Orthopterans, grasshoppers and crickets, have more species).
With funding from the NSF and in collaboration with 1KITE, I have collected genomic data from over 100 species of Blaberoidea, with over 200 total species planned.
In collaboration with Frederic Legendre, we hope to resolve the relationships of the major Blaberoidean lineages and discover the biological drivers of their diversification. We will explore how changes in historical biogeographic distribution and novel traits in sexual morphology relate to changes in diversification rate.
In collaboration with both Frederic Legendre and Brian O'Meara, we hope to resolve the phylogeny of Blaberidae. Blaberidae is one particularly troublesome region of the phylogeny because it follows the classical rapid radiation with short inter-nodes and long tips. We are applying novel evolutionary models to resolve this problem.
Traditional Systematics
(morphology based)
Fossil cockroaches
Although cockroaches are ancient survivors in urban myths, in reality they are probably much younger than scientists once thought.
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This is the conclusion we come to in our 2019 publication in Proceedings of the Royal Society B. In this publication we infer divergence dates based on phylogenomic data and a complete revision of the fossil record. My revision of the fossil record started with my 2017 publication that reviewed the oldest described crown-cockroach fossils. In both publications we give extensive evidence showing that most fossil Blattodea (and close relatives) are described based on data that does not hold up when held to high scrutiny. As a result, we find that the oldest (crown) cockroach specimen is 125 million years old and the oldest Blaberoidea specimen is 54 million years old.
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In 2018, colleagues and I redescribed a fossil from France that was originally classified as a praying mantis. In this paper we discuss evidence that this fossil species, Prochaeradodis enigmaticus, is actually more likely to be a cockroach. Although we aren't sure what kind of cockroach it is, there is a possibility it is the same species as the one pictured on the left, "Gyna" obesa.
Taxonomy of Guianan cockroaches
Guyana is known as a region of pristine forests and high diversity. However, the cockroaches of Guyana are poorly studied relative to the other strictly guianan countries (Suriname and French Guiana). In studying the cockroaches from this region we continue to find new records for the country as well as altogether undescribed species.
Given that we estimated 70 species to be present in two small coastal regions of Guyana (Evangelista et al, 2014), the total number of species known from the country is likely a large underestimate.
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However French Guiana is much more well sampled. As a result, it is known as one of the most diverse hotspots of cockroach diversity. Yet, even from this well-sampled region there are many new species, which we are currently describing.
Taxonomy photo collage
If you need cockroaches identified please email me after you look at this photo of common cockroaches.