Research
Research in my lab focuses on the evolution of mating preferences and mate choices. By transcending boundaries of field-based behavioral ecology and lab-based quantitative genetics and genomics, we aim to answer fundamental questions about evolution and genomics of mating preferences that will eventually help us causally link selective forces in real natural populations to variation in mating preferences to the underlying genetic, epigenetic, and genomic mechanisms.
Study system
We use crickets as our model system in studying mating preferences. One group of crickets we work on are the Laupala crickets endemic to the Hawaiian islands. In this genus, both male song and female acoustic preference have diverged repeatedly among lineages but remained coordinated within a lineage, resulting in species-specific mating signals. Sexual selection is thought to be the primary driver of rapid speciation in this genus. With a reference genome available and the ability to be maintained and hybridized in the lab, the Laupala crickets provide an ideal context to study the genomic basis of mating preferences.
Another group of crickets we will work on are the North American Gryllus crickets where a lot is known about the neurological basis of both singing and song discrimination, offering a candidate to perform targeted genetic, epigenetic, and genomic probing guided by neurobiology. As a locally available system, the Gryllus crickets also offers an opportunity to conduct long term field behavioral and ecological experiments.
We use crickets as our model system in studying mating preferences. One group of crickets we work on are the Laupala crickets endemic to the Hawaiian islands. In this genus, both male song and female acoustic preference have diverged repeatedly among lineages but remained coordinated within a lineage, resulting in species-specific mating signals. Sexual selection is thought to be the primary driver of rapid speciation in this genus. With a reference genome available and the ability to be maintained and hybridized in the lab, the Laupala crickets provide an ideal context to study the genomic basis of mating preferences.
Another group of crickets we will work on are the North American Gryllus crickets where a lot is known about the neurological basis of both singing and song discrimination, offering a candidate to perform targeted genetic, epigenetic, and genomic probing guided by neurobiology. As a locally available system, the Gryllus crickets also offers an opportunity to conduct long term field behavioral and ecological experiments.
Genetic basis for signal-preference coevolution
Divergence of mating preferences is ultimately a coevolutionary problem: while preference and the preferred trait can each diverge among lineages, they must remain coordinated within a lineage for mating to occur. As preference and sexual trait are often different types of traits involving distinct systems and developmental pathways, what genetic and genomic mechanisms enable preferences and preferred traits to evolve in coordination? My past research in Dr. Kerry Shaw's lab at Cornell University has focused on testing hypotheses on the genetic architecture underlying song-preference coevolution in the Laupala crickets. Our data offered strong evidence for genetic coupling (a shared pleiotropic gene or tightly linked genes) and highlighted an important role it plays in mediating signal-preference coevolution (Xu and Shaw 2019a, 2019b, 2021). Through annotation of targeted genomic regions, we have also identified a list of candidate genes for variation in both male singing and female preference.
Future research in this direction will seek to use behavioral experiments and functional genomics to validate candidate genes in collaboration with the Shaw lab at Cornell university. In addition, we will leverage the power of neurobiology in collaboration with neuroethologists in the Gryllus crickets to pinpoint neurogenetic basis of responses to different male songs.
Divergence of mating preferences is ultimately a coevolutionary problem: while preference and the preferred trait can each diverge among lineages, they must remain coordinated within a lineage for mating to occur. As preference and sexual trait are often different types of traits involving distinct systems and developmental pathways, what genetic and genomic mechanisms enable preferences and preferred traits to evolve in coordination? My past research in Dr. Kerry Shaw's lab at Cornell University has focused on testing hypotheses on the genetic architecture underlying song-preference coevolution in the Laupala crickets. Our data offered strong evidence for genetic coupling (a shared pleiotropic gene or tightly linked genes) and highlighted an important role it plays in mediating signal-preference coevolution (Xu and Shaw 2019a, 2019b, 2021). Through annotation of targeted genomic regions, we have also identified a list of candidate genes for variation in both male singing and female preference.
Future research in this direction will seek to use behavioral experiments and functional genomics to validate candidate genes in collaboration with the Shaw lab at Cornell university. In addition, we will leverage the power of neurobiology in collaboration with neuroethologists in the Gryllus crickets to pinpoint neurogenetic basis of responses to different male songs.
Variation, evolution, and genetics of choosiness
Variation in how choosy choosers are is common. A female cricket may mate with most males it visits whereas another female may reject most males. In Pride and Prejudice, whereas Elizabeth is picky among her male suitors, Charlotte was ready to marry the first man who comes her way. Where does such variation come from? What is the general pattern of variation? Can such variation be subjected to selection? What are the proximate mechanisms for this variation? What are the effects of variation on trait evolution and speciation?
This research program aims to answer these questions by combining field and lab based behavioral experiments, quantitative genetics, differential gene expression, QTL mapping, and functional genomics, offering a rich context for students to learn skills and design related independent projects.
Variation in how choosy choosers are is common. A female cricket may mate with most males it visits whereas another female may reject most males. In Pride and Prejudice, whereas Elizabeth is picky among her male suitors, Charlotte was ready to marry the first man who comes her way. Where does such variation come from? What is the general pattern of variation? Can such variation be subjected to selection? What are the proximate mechanisms for this variation? What are the effects of variation on trait evolution and speciation?
This research program aims to answer these questions by combining field and lab based behavioral experiments, quantitative genetics, differential gene expression, QTL mapping, and functional genomics, offering a rich context for students to learn skills and design related independent projects.
Sexual selection and acoustic communication in a changing world
Human activities are changing the world animals live in rapidly. It is becoming increasingly difficult to find the so-called pristine habitat that has not been altered by human activities in some ways. Artificial lights, noises, chemical pollutants, man-made structures, and heat we generate all represent new realities for animals. What do these mean for animals? How do human activities affect sexual communication and mate choice? Where is sexual selection headed in this changing world?
We are interested in answering some of the questions using the Gryllus crickets as a study system. A few topics we are currently interested in are:
Human activities are changing the world animals live in rapidly. It is becoming increasingly difficult to find the so-called pristine habitat that has not been altered by human activities in some ways. Artificial lights, noises, chemical pollutants, man-made structures, and heat we generate all represent new realities for animals. What do these mean for animals? How do human activities affect sexual communication and mate choice? Where is sexual selection headed in this changing world?
We are interested in answering some of the questions using the Gryllus crickets as a study system. A few topics we are currently interested in are:
- How do chemical pollutants such as insecticide residues and endocrine-disrupting chemicals from plastic affect singing, song preference, and phonotaxis of crickets?
- How do man-made structures in urban areas affect sound propagation and sound localization? And does the effect translate to plasticity or adaptation in singing or phonotaxis behavior of crickets living in the city?
- What are the evolutionary consequences of the behavioral changes in natural population?