Old photograph of people from the 1800s

RESEARCH:: Celebrating Darwin

Phylogenetics: Reconstructing the Tree of Life
By Dr. Jason R. Cryan

What species is the closest living relative of the human species? Chimpanzees? Gorillas? Orangutans? And why does it matter? Biological evolution is a process by which groups of living organisms change over time. As populations of organisms separate and diverge from each other, they can become separate species, can hybridize with other populations, or they can die out and become extinct. They can even do all of those things! In this way, groups of organisms are connected to each other through time in a series of branching relationships that can be thought of as an extended genealogy, or a “family tree”—but of groups, rather than of individuals. The set of hierarchical relationships linking species through time is called a phylogeny, and the science of reconstructing and interpreting the importance of these relationships is called phylogenetics.

Knowledge of the evolutionary past of a species often leads to an enhanced understanding of that species, itself—why it looks and behaves as it does, lives where it does, and eats what it does.

The science of phylogenetics allows researchers to more accurately understand and describe life on Earth. What’s more, knowledge of the evolutionary past of a species often leads to an enhanced understanding of that species, itself—why it looks and behaves as it does, lives where it does, and eats what it does. In fact, most modern branches of the biological sciences (including molecular biology, genetics, development, behavior, epidemiology, ecology, systematics, conservation biology, and forensics) rely heavily on phylogenetics to provide baseline biological information.

My phylogenetic research at the New York State Museum focuses on reconstructing evolutionary relationships among planthoppers, spittlebugs, and treehoppers—groups of plant-eating insects that include a number of agricultural pests of worldwide economic importance. These fascinating insects are found all over the world, including some in New York, but are most diverse in the tropics; some, like the “peanut-headed” bug (Fulgora laternaria; pictured above) are even thought of as icons of tropical biodiversity.

Although there are many researchers interested in more effective ways to control the pest species in these insect groups, very little is known about how the thousands of included species are related or how they evolved as they did. Funded largely by competitive research grants from the National Science Foundation, I travel all around the world to collect specimens of these insect species, then bring the specimens back to my laboratory at the State Museum, where I use comparative DNA sequencing to generate evidence that I use to reconstruct the phylogeny of these bugs.

The results of my studies help me and my colleagues to more accurately describe and classify insect biodiversity and to answer questions about the biology of these amazing insects. Other scientists will be able to use the baseline evolutionary information that my research generates to propel their own research, perhaps someday even working out better methods of pesticide-free control of important agricultural pests!

Dr. Jason R. Cryan is an entomologist at the New York State Museum. He directs the Museum’s Laboratory for Conservation and Evolutionary Genetics.
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