My research interests are centered on the evolution of one of the most diverse and ecologically important groups of organisms on Earth: the ichneumonid parasitic wasps (Hymenoptera, Ichneumonidae). I am particularly interested in the processes that generated the impressive diversity of life history strategies, morphological adaptations and ecological traits seen in these wasps. My work to elucidate these questions combines a robust phylogenetic framework with statistical tools such as phylogenetic comparative methods and geometric morphometrics. In the process of investigating these issues, I also invest in unraveling the largely unexplored wasp biodiversity, conducting projects of revisionary systematics and describing new species.
Integrating genomics and geometric morphometrics to unravel the diversification of parasitic wasps
My main research project aims at unraveling the impact of convergent life strategies on the phenotypic evolution in a hyperdiverse lineage of parasitic wasps. Genomic data from ultraconserved elements (UCEs) are combined with phenotypic data collected and analyzed with geometric morphometrics to study evolutionary pathways in the morphospace and elucidate the constraints in morphology posed by convergent evolution.
In my current research, I integrate molecular and phenotypic data to reconstruct changes in host use across lineages of parasitic wasps; to identify correlation between phenotypes and particular life strategies (the use of a specific host taxon or the timing of parasitization, for example); and to quantify the overlap in the morphospace among lineages with similar life history. The goal is to lead to a better understanding of the role of parasitism life strategies in shaping phenotypes and of the constraints in morphology posed by convergent evolution.
Systematics of cryptine wasps (Hymenoptera, Ichneumonidae, Cryptini)
This is my primary and most basic line of research. Since the beginning of my career, I have been dedicated to understand the evolutionary history of Cryptini and describe and classify the biodiversity of this hyperdiverse group of wasps. Since 2008, I have described 115 new species and three new genera, and many more new species are identified and waiting to be described! I also use molecular and morphological data to investigate the evolutionary history of cryptines and other ichneumonid groups, a line of work that serves as a basis to the broader evolutionary and ecological aspects of my research.
Morphological diversification
One of my main research interests is the study of phenotypic adaptations, particularly convergent evolution. In the past, I have focused on the evolutionary pathway of adaptations related to finding and assessing deeply concealed hosts by cryptine wasps. I used comparative methods and geometric morphometrics in a phylomorphospace approach to advance the idea that these adaptations are part of a complex morpho-functional system, and to show how that affects the evolution of body shape in the associated lineages. I have now expanded this investigation to other ichneumonid lineages and other types of life strategies, such as the developmental stage of the host attacked by different groups of wasps.
Ichneumonid phylogenomics
Thanks to funding granted by the Global Genome Initiative, I am currently leading a project aiming at reconstructing the phylogeny of the whole family Ichneumonidae using data from genomic ultraconserved elements (UCEs; http://ultraconserved.org/). Ichneumonid parasitic wasps comprise one of the largest insect lineages, but the lack of a comprehensive phylogeny currently hinders our understanding of their diversification process. Our project combines the efforts and expertise of multiple researchers throughout the world with an unprecedented genomic dataset to generate a powerful phylogenetic framework. UCE data is currently being harnessed to generate a phylogeny of 800+ species. Total-evidence dating with a rich fossil sampling will be used to date the tree, putting ichneumonid diversification into temporal context, and the evolution of biological traits will be assessed through ancestral state reconstructions.
Sequencing and annotating whole genomes
The most recent expansion of my research program involves using functional genomics to elucidate key aspects of the diversification of parasitic wasps. I have been investigating the relationship between some groups of parasitic wasps and viral symbionts that help to disable the immune system of their hosts. These viruses, called polydnaviruses, have been “domesticated” independently by two diferente groups of parasitic wasps, the Braconidae and the Ichneumonidae. Previous research has shown that the whole viral genomes are incorporated into the wasp’s DNA, and I have been working on mapping these viral insertions in a comparative framework. To that end, I have sequenced the whole genome of the ichneumonid wasp Campoletis sonorensis. I have been collaborating with researchers from the Institut National de la Recherche Agronomique in France to compare the distribution of viral segments between C. sonorensis and another wasp species, Hyposoter didymator. We have found that sequences from the viral genome are scattered across the wasp genome, in contrast with the viruses found in Braconidae, which are clustered in large blocks. We have also found that elements of the viral genome that are functionally different also show different degrees of conservation between the two ichneumonid wasps. The proviral genes that help to destroy the host immune response are species-specific, as they need to be fine-tuned to host physiology. Meanwhile, the viral elements related to particle production and replication are conserved, likely reflecting the genomic architecture of the ancestral vírus. The results have recently been published at BMC Biology!
Upcoming: more genomes!
Thanks to a grant from the Smithsonian, we were recently able to sequence whole genome data for 100+ ichneumonid species. We now plan to look at the diversity in genes associated with key biological processes and test if these are correlated with life strategy traits such as endo- versus ectoparasitism, host specificity and developmental stage. We will also test if independent lineages with the same hosts convergently evolve similar peptide profiles. The results will be used to test current hypotheses about ichneumonid diversification; they will also make the Ichneumonidae one of the best-characterized groups of insects from a genomic perspective!
Other ongoing projects and interests include:
- Color patterns: Cryptines display an impressive variety of color patterns, which seem to show a pattern of convergence across lineages. I am investigating the phylogenetic and geographic signals shown in color patterns in a group of cryptine wasps and what these patterns can tell us about evolutionary processes.
- Surveys and inventories: Only by continuously documenting species occurrence we can draw a truly informative picture of Earth’s biodiversity and understand which environmental factors help to shape communities and ecosystems. In partnership with colleagues, I am involved in several surveys and community ecology studies throughout the Neotropics.
Fieldwork
Working in the field is a fundamental component of my research and my life. I have extensive field experience in environments throughout South America, from the lush Amazonian Forest to the arid habitats of Central Chile. I am continuously seeking opportunities for fieldwork and the external funding to support these initiatives.
Bernardo F. Santos 