LAWRENCE — Just what is a species? It’s a surprisingly difficult question of biology. One University of Kansas researcher, Jenny Archibald, recently received a grant from the National Science Foundation to explore definitions of species and better delimit the ways that human beings characterize other organisms.
“Biology is complicated,” said Archibald, a research scientist with KU’s Biodiversity Institute and Department of Ecology and Evolutionary Biology. “Scientists are starting to agree that there’s no single thing that you can look at to tell species apart. We need to weigh multiple factors and be aware that some species are going to differ in different ways.”
The abundance of life on Earth is so multifaceted, Archibald said, that several tools are necessary to classify and name groups of organisms. Some of these approaches date back hundreds of years to Carl Linnaeus, who invented modern taxonomy, and others are brand-new technologies.
“The problem is that some groups out there look totally different, but they can form hybrids together,” said Archibald. “Or, if you look at their genes, they are very similar. Then there are other groups that look basically the same, but their genes are very different or they can’t form offspring with each other. So that’s where there has been a lot of debate as to how to tell these things apart.”
In addition to the time-tested methods of examining and measuring organisms and understanding if they’re able to mate, Archibald and her colleagues are using newer methods to delineate species. These include examining DNA sequences and “ecological niche modeling,” a technique that Archibald said was in part pioneered by fellow KU researcher Town Peterson.
“It’s a new way to look at ecological differences,” said Archibald. “You model them on a map. You take sets of different environmental characteristics and say, ‘This chunk of the map looks like it would be a good area for the species, and this does not.’ And if we do this with some of these groups that we think may or may not be different species, then we can see if they overlap on the map or if they’re separate. That can help make clear in a more detailed and quantifiable way whether they’re ecologically distinct.”
With colleagues Susan Kephart of Willamette University and Theresa Culley of the University of Cincinnati, Archibald’s current work involves the study of two closely related flower genera, Camassia (or camas lilies) and Hastingsia (or rush lilies).
“They’re useful because they’re a taxonomic mess,” she said. “If you’re going to throw a lot of data at a taxonomic question, you don’t want to use something so clear cut that you don’t need that much data. Camassia has six species — but one of those species has eight subspecies. And there have been a lot of questions as to how those should be arranged. Some of them seem like they should be moved into entirely other groups. There’s been disagreement about how they should be delimited.”
The KU researcher said that her fieldwork includes locating and marking the flower species, measuring petals and leaves, taking samples for DNA extraction and hand pollinating between the species to see if they can form seeds. In the lab, she is working with undergraduate researchers to sequence DNA regions from the chloroplast and nuclear genomes. Differences in nucleotides can be used to trace relationships among individuals and populations.
Although Archibald’s work is with flowering plants, the results of her research and the techniques she develops could apply across the different kingdoms of species.