CEB Committe on Evolutionary Biology

Spotlight : Lu Yao

Lu Yao

Lu Yao with a crab-eating macaque in Bali.

I am interested in the evolution of animals on islands. There is a phenomenon called the “Island Rule”, which states that large-bodied organisms evolve smaller body size on islands most likely due to a lack of resources while small-bodied organisms evolve larger body size on islands because of decreased competition and predation. However, it is unclear whether or not this is a universal rule and we don’t really know what happens to specific anatomical parts, such as brain size, when animals evolve on islands. So I am studying island dwarfing by comparing mainland and island forms of deer, pigs, gibbons and macaques. Geographically, I am studying the specimens from the Southeast Asian region. Island size and island type may play a role in body size evolution so a region like Southeast Asia with tons of islands of various sizes is perfect for my research.

Although I focus on this tropical region, it isn’t really my field site. Instead of working on live organisms, I use specimens that have already been collected in the first half of the 1900’s by collectors and hunters. These specimens are kept at natural history museums around the world. Those that have the largest collections of the taxa I am studying are The Field Museum in Chicago, the American Museum in New York, the Smithsonian Institute in DC, the Natural History Museum in London, the Naturalis Biodiversity Center in Leiden, and the Lee Kong Chian Natural History Museum in Singapore. I utilize these spectacular museum collections in a number of ways to answer my research questions. First, I am testing whether or not island dwarfing is a general rule by comparing body sizes to island size. Second, I am looking at brain size to see if there is a decrease or increase in absolute and relative brain size in mammals that evolved on islands. Finally, I collect 3D shape data of the skulls so that I can understand changes in skull shape between mammals from the different islands and the mainland. Working in museums is pretty awesome because I have the chance to roam around the exhibits to learn about natural history, and I get to work behind the scenes where museums keep most of their collections. It can be a bit tedious performing the same measurements on hundreds of specimens, but jamming to some music really helps.

Additionally, I am interested in the evolutionary relationships between individuals. Relationships between and within species are important when analyzing comparative data, and the need to use phylogenetic techniques for analyzing comparative data has been stressed by various scientists. However, studies of island dwarfism have rarely taken evolutionary relationships into account, as is needed to exclude effects of closely related species. Therefore, I am using next generation sequencing techniques in an ancient DNA lab at University of Illinois Urbana-Champaign to sequence the mitochondrial genomes of Southeast Asian long-tailed macaque museum specimens. From the DNA sequences, I can reconstruct a within species phylogeny, which I can use to tease apart relationships between island populations when analyzing body size, brain size and skull morphology, which is an essential step when studying a process that occurs only within species or very closely related species. Furthermore, the resulting phylogeny can reveal when specific lineages arrived on the various islands in Southeast Asia, which is an important variable to take into account.

I am excited about using museum specimens in novel ways to answer research questions. In the future, I am interested in utilizing museum collections by combining traditional morphological methods with next generation sequencing to answer research questions. In addition to just research, use of museum collections allows me to travel around the world and experience various cultures by interacting with locals, seeing touristy (and non-touristy) attractions, and trying new foods!

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