Academic interests and projects
The systematics of "Canthonina" (Scarabaeinae, Deltochilini)
By "Canthonina", I mean Canthon and the other groups with which it is closely related within Deltochilini. Or, more specifically, the groups that are likely nested within Canthon. My master's thesis, a revision of Sylvicanthon, was the first step toward the modernization of our understanding of the systematics of the group. Over the years, I have gathered material from several museums to start a revision of Glaphyrocanthon and Anisocanthon, and they will likely be the first groups that I will investigate in this project. But, nowadays, I consider that some aspects of Sylvicanthon merit reevaluation (e.g., the validity of S. mayri, S. monnei and S. furvus as independent species; my likely incorrect statement that there would be no differences between the male genitalia of S. edmondsi and S. attenboroughi; etc), so they will also be re-examined.
Systema Scarabaeorum
This is the working title of a project of mine: a catalog of all the literature published on the world scarabaeoids. My idea is something in the same vein as Miguel A. Monné's catalog of the Western Hemisphere Cerambycidae.
Myself at the Ernst Mayr Library, Harvard University, with a copy of the first edition of Carolus Linnaeus' Systema Naturae (1735), written when the author was only 28 years old. Despite its folio size in its first edition, the content of Systema Naturae was still limited, as the book consisted of only 12 pages. But it would eventually grow and, by its 1767 12th edition, the last authored by Linnaeus, it encompassed more than 2,400 pages organized into three volumes. Following the spirit of the Enlightenment, Systema Naturae was the starting point for modern systematics. The working title of my world scarab catalog project, Systema Scarabaeorum, is a homage to Linnaeus and his dream still to be fulfilled of a complete catalog of nature.
The evolutionary biology of the Ateuchus dung beetles:
A model for the study of speciation in Coleoptera
For many years, the systematics of Ateuchus, except for the North American and Costa Rican fauna, was completely unknown. No one knew how many species there are, where they occur, how to identify them, and only fragmentary information about the biology of a handful of the species was available in the literature. Over the past years, however, I have been working to solve all these problems. My studies of over 45 thousand specimens concluded that 132 species of Ateuchus exist distributed all the way from the US state of New York south to northern Argentina. The diversity of forms and ecologies is immense. There are some widespread species, which may be either phenotypically uniform throughout their ranges or show multiple geographical clines and, thereby, be multiform. Other species have a very limited occurrence, being sometimes known from a single locality. Some species form superspecies; i.e., clades of allopatric species. These allospecies may be homomorphic between themselves or highly heteromorphic. Other clades form species flocks, i.e., clades whose constituent species are all sympatric. Most species seem to have a continuous distribution, forming a single metapopulation, whereas a few others are clearly broken into two or more geographical isolates. These isolates may be heteromorphic or homeomorphic. Finally, a few groups show evidence of constituting, instead of a single species, an enogameon; i.e., a group of semispecies. These putative semispecies form population intergradations whose one of the varying characters forms a stepped cline and is, such as the shape of the male genitalia and the secondary sexual characteristics, hypothesized to play a role in the sexual behavior of dung beetles. As such, the different states giving form to the stepped clines may act as biological reproductive barriers that partially isolate semi-independent metapopulations. This is one of the findings that most fascinated me during my PhD investigation and which led me to dive into the speciation literature. Both perplexed to see how little beetles, one of the most speciose groups of animals, have contributed to our understanding of speciation and curious to fully understand the evolution of the Ateuchus, I decided to pursue a goal: to make Ateuchus a model system for speciation studies among Coleoptera. To illustrate what I have in mind, my aim is for Ateuchus to become to Coleoptera what Heliconius represents to Lepidoptera, Drosophila to Diptera, Partula to gastropods, cichlids to fishes, and Darwin's finches and the Melanesian avifauna to birds.
My plans are to study the evolutionary biology of the Ateuchus in the following phases:
1- Foundations: (a) cataloging everything that has ever been published about the group over the past 250 years since the first species was described by Fabricius; (b) museology: the study of all relevant museum collections in search of every specimen available for study; (c) writing a complete history of the systematics of the Ateuchus; (d) nomenclature: solving all nomenclatural issues related to the names of the Ateuchus. Completed.
2- Speciology, phase I: Species delimitation, population structure, geographical variation and speciation patterns based on morphological and distributional data. In progress.
3- Phylogenetics and evolutionary morphology. The phylogenetic relationships between the Ateuchus species and the evolution of their morphology based on morphological and molecular evidence. In progress.
4- Biogeography. The aim here is to understand three main points: (a) the participation of Ateuchus in the Great American Biotic Interchange sensu lato. When did the Ateuchus move northwards from South America, and how many different lineages did so? (b) the interconnections between the Amazonian and the Atlantic Forest faunas of Ateuchus through the South American Dry Diagonal; (c) the biogeographical history of the Ateuchus populations in the Lesser Antilles. In progress.
5- Speciology, phase II: Species delimitation and phylogeography based on molecular and more detailed morphometric data. Here, I'm referring particularly to the "difficult" cases involving possible semispecies and hybrid zones as cited above.
6- Speciology, phase III: The direct, functional study of the biological reproductive barriers, especially: (a) the anatomy of the male genitalia and female cryptic choice; (b) the role (if any) of secondary sexual characteristics in courtship and in promoving reproductive isolation; (c) the role (if any) of sex pheromones as reproductive barriers in Ateuchus (as suggested by details of their anatomy and by the biology of other, better-known dung beetles); (d) the role (if any) of the microsculpture and punctation of the integument as reproductive barriers.
7- Ethology: (a) the feeding habits of the Ateuchus; (b) their nesting behavior; (c) the ecological relationships between the Ateuchus and other organisms (e.g., myrmecophily, commensalism in mammal burrows, etc).
8- Functional morphology: Do the taxonomic characters of the Ateuchus contribute to their fitness? Do they have any function in the life of the Ateuchus? In essence, do the taxonomic characters evolve through natural selection or are they functionless and evolve solely by drift?
9- Macroecology: Why does the richness of Ateuchus species apparently peak in the tension zones between the southern Amazon and the Cerrado and between the Cerrado and the central Atlantic Forest?
10- Synthesis.
An Ateuchus tona, a species from the Colombian Andes recently described by me and colleagues. Another 54 new species from the entire Neotropical region are under description for my PhD thesis.
The spatial distribution of species richness of Ateuchus.
The Danish entomologist Johan Christian Fabricius (1745-1808), a student of Linnaeus and the describer of the first Ateuchus: A. squalidus (Fabricius, 1775), from material collected in 1868 by Sir Joseph Banks in Rio de Janeiro. The specimen still survives in the London museum, where I studied it in 2019. Fabricius would later describe another Ateuchus, A. capistratus Fabricius, 1801, from the United States. This latter name is involved in two nomenclatural problems, to which I propose solutions in my thesis.
One of the scenarios for the colonization of the Lesser Antilles by Ateuchus calcaratus. Particularly intriguing about these populations is the fact that St. Lucia, even though lying at the center of the island chain, has the most divergent of the populations in terms of its phenotype. How can this be explained? I elaborated four alternative hypotheses to explain this pattern, one of them, the Founder Effect Hypothesis, is shown above. This discussion is part of my PhD thesis, but a future molecular approach will be necessary in order to test these alternative scenarios.
Relative abundance between four species composing an Amazonian clade of Ateuchus. Note that while one of the species is allopatric in relation to its sisters, the other three form, at least in part of their distribution, a species flock.
The terminology, theory, history and philosophy of the species problem
This is more general than the three previous projects on scarabs. While working and reading for the Ateuchus project, I've been developing a set of terms to refer to population entities and processes related to speciation from the point of view of a practicing zoological systematist (e.g., hologameon for an entity composed of two or more semispecies, as mentioned above; a syngameon is a kind of a hologameon, an eikogameon being another). Some of them appeared in my PhD thesis, but others will need more reading and knowledge on my part.
I've also been developing what I consider to be a new way to look at the species problem. Instead of focusing on species "concepts", I propose discussing the matter in terms of species theories. For instance, although Mayr himself used the term "concept" to refer to his view of species, I believe it is more accurate to say that he had a theory (or, even better, a set of theories) about the nature and origin of biological diversity and of the process of diversification. The proposal is akin to what Mayr himself did in relation to the so-called Darwin's "theory": Mayr showed that Darwin did not elaborate a single theory, but a full set of them to explain the history of life. The current theory of species, the continuation of the synthesis theory (which I call the "myxiological species theory", after Dubois' term, or the theory of the reproductive grades), involves several independent elements, such as (1) the fact that species are reprocutive communities, (2) that they are the product of an evolutionary process, (3) that they constitute populations, not types, (4) that the multiplication of species (speciation) proceeds by the development of biological reproductive isolation usually in a population, gradual way instead of by "hopeful monsters", so much so that populations can be found at all levels of reproductive compatibility and independence (i.e., they can be at any place of the speciation continuum), (5) that allopatric speciation is likely the main mode of speciation, but that sympatric and parapatric speciation are conceivable, (6) that there are several ways through which gene flow can be prevented between populations and that, therefore, there is no single form of biological reproductive isolation that is more "legitimate" than others, etc. In sum, instead of trying to classify different species views into narrow "concepts" (i.e., instead of looking for one or two traits to classify ideas into types, like the "typological concept", that, in reality, is just a wastebasket class for all sorts of theories on species with typological elements), I believe it is more productive to think of species theories, which are made up of sets of independent concepts that may be shared through homology, introgression or homoplasy with other theories. For example, Lamarck's theory shared non-fixism with the modern species theory, but, unlike the modern theory, he was a species nominalist; on the other hand, John Ray was a species realist, but a fixist. So, the modern theory shares some elements with Lamarck's, but others with Ray's.
These ideas are, of course, all premature and someone more knowledgeable than me on the subject may find a great number of problems with them. But my point here is just to tell you that I'm thinking about these topics and that I plan to continue doing so.
I beside a portrait of English evolutionary biologist Sir Edward Bagnall Poulton (1856-1943), at the Oxford University Museum of Natural History, where Poulton worked for decades. Poulton was one of the early developers of the modern view of species as evolving reproductive communities.
One of the illustrations that I prepared for the chapter of my PhD thesis dealing with the theory and terminology of speciology as applied in my study of the evolution of Ateuchus.
The life of scarabs
This will be a kind of textual synthesis of everything known about scarabs. My models are Gonzalo Halffter's books The Natural History of Dung Beetles of the Subfamily Scarabaeinae (with Eric Matthews) and The Nesting Behavior of Dung Beetles (with W.D. Edmonds), Clark Scholtz and colleagues' Evolutionary Biology and Conservation of Dung Beetles, and Bert Hölldobler and E.O. Wilson's The Ants. I've been giving classes since 2013 on the evolutionary biology of Scarabaeoidea and my plan is, over the years, and while I conduct the research for Systema Scarabaeorum, to expand my knowledge and the content of my classes into this book.
A male Megasoma anubis (Scarabaeoidea: Dynastinae) eating the sap of some rotten bananas. This beetle was caught by me at Itatiaia National Park in late 2010. I decided to keep it alive for as long as I could and see if I would learn anything interesting about its behavior.
The history of the subspecies concept
Unlike the species concept, whose history has been written and debated at least since the very early 20th century, little has been said about the history of the subspecies concept. I'm interested particularly in understanding the evolution of Ernst Mayr's changing ideas on subspecies. I have developed some hypotheses to explain this, but I would need first to read more of Mayr's writings, his correspondence and manuscripts, and the rest of the literature on the subject published during Mayr's lifetime. This is necessary not only to confirm my present conclusion that his views did change over time, but also to refine my hypotheses as to why. This is something that I plan to do in the future. The last time I was at Harvard, I contacted the general library, where Mayr's archives are housed, but, unfortunately, did not have time to actually work on this project. In the future, I'll return there to carry out this work.
The German-American ornithologist, evolutionary biologist, and historian and philosopher of biology Ernst Mayr (1904-2005). I first read a book by Mayr while in high school, and since then he has become an intellectual hero of mine. His views and writings shaped our understanding of evolution and the origin of species and will, I think, continue to do so for many more decades to come. Since I unfortunately never had the chance of meeting him (I was born too late for my career to overlap with Mayr's), here I'm photographed in 2018 beside a portrait of him hanging on a wall of the Ernst Mayr Library, at the Museum of Comparative Zoology, Harvard University.
General interests
My interests in evolutionary biology are vast. They span through as diverse fields as the systematics of Scarabaeoidea, all biological aspects of Coleoptera, the theory, philosophy, and history of systematics, zoological nomenclature, speciology, sexual selection, biogeography, sociobiology, paleoanthropology, the evolution of the body plan of the great animal groups, and the history of the evolutionary thought.
