Millions of Earth's species may have yet to be identified, according to a recent National Geographic article. But today, it's millions minus two: New algae species recently emerged from a Japan lake, and one of them is named after UA research associate Patrick Ferris.
A recent paper published in the Journal of Phycology by researchers at the University of Tokyo and Keio University describes two new species of algae, one of which is dubbed Volvox ferrisii, in honor of the scientists’ Canadian-born colleague.
“Most people see the algae that are clogging up their pools,” Ferris said. “They don’t see the little ones.”
Volvocine algae dwell almost everywhere, Ferris said: “The smaller species can be in nutrient-rich, damp soils, and the larger species tend to be in small bodies of water or even large lakes.”
“In water, they tend to be near the surface to be near light,” he added. Algae are primary producers, meaning that they use a compound called chlorophyll to make food from inorganic compounds such as nitrogen and phosphorous and energy from sunlight.
Water-dwelling colonies have the ability to migrate to deeper waters at night to take in nutrients that are more abundant toward the bottom of lakes and ponds, Ferris said.
V. ferrisii is just such an organism. A multicellular, colonial algae, born each Spring from seed-like structures called zygotes that have overwintered in the scum at the bottom of lakes and ponds, V. ferrisii likely spends its days migrating up and down the water column, following the food and sunlight.
Ferris has spent most of his career studying algae. After receiving his Bachelor of Science from the University of Western Ontario in London, Ontario, Canada, and his doctorate at Cornell University in Ithaca, N. Y., Ferris began studying the molecular genetics of mating and sex determination in the single-celled algae called Chlamydomonas reinhardtii as a postdoctoral researcher at Washington University in St. Louis, Mo.
For Ferris, algae have a unique story to tell through the evolution of their genes.
“The appeal of algae as model organisms is that the progression from single-celled algae like Chlamydomonas to multicellular colonies like Volvox is fairly recent,” Ferris said. “When unicellular species evolve into multicellular species, the very units on which evolutionary processes work have changed.”
The genes responsible for this evolution are easier to identify in the recently evolved algae, Ferris said. Also, he added, there are many intermediate species between single-celled algae and multicellular colonies, giving scientists an excellent opportunity to study how genetics have led to changes in how the cells function and reproduce.
Volvox species are important model organisms to study these systems, Ferris said, especially since the genome sequence of the species V. carteri was published in 2010.
Algae are haploid, meaning that each cell has only one set of chromosomes. Humans and most other animals are diploid, each cell having two sets of chromosomes, one from each parent.
Being haploid means that the diversity of cells is limited by the need to have many of the same genes for normal cell functions in each cell. Since there is only one of each chromosome, there is no backup copy with which evolution could experiment with new or different genes.
Volvox colonies, called spheroids, are comprised of about 2,000 cells, most of which are somatic, Ferris said: “They aren’t able to divide to make a new colony.”
Only a few dozen cells in a Volvox colony are germ cells, capable of reproduction. “During the reproductive phase of the colony’s life cycle, these cells gradually grow larger and undergo division to make an embryo that will go on to become a new Volvox colony,” Ferris explained.
“A question that this raises,” Ferris said, “is how these haploid organisms can tolerate having this large non-recombining region of genes including those genes that control sex determination and are evolving away from each other, toward two different sexes in germ cells, and yet retain the same functions in all the neighboring genes.”
Having commenced his study of Volvox at Washington University, Ferris decided to take a leap with his career – across the Pacific Ocean.
“I was feeling adventuresome and arranged a postdoc with a Volvox research group in Japan,” Ferris said.
With a grant from the Japanese Society for the Promotion of Science, Ferris worked with a Japanese research team sampling various members of the Volvox genus from lakes and ponds.
Once, while sampling a lake near the RIKEN Institute where they were working, the team found a new species with many of the same characteristics as the newly discovered V. ferrisii. The particular strain was not investigated at the time, and Ferris speculated that it might have been lost from the lab.
Ferris returned to the U.S. to work at the Salk Institute in San Diego, where he completed his study of the genetics of the Volvox mating type. The research was published in Science in 2010.
Meanwhile, unbeknownst to Ferris, the Japanese researchers returned and resampled the lake, this time isolating and identifying two new algae species.
Ferris had no idea the group intended to name one of the new species after him. The revelation came with the recent publication of the paper in the Journal of Phycology, which declares the discovery of the two new species, one of which was dubbed V. ferrisii.
“It was a pleasant surprise, to have somebody name something after you,” Ferris said. The other species was named V. kirkiorum, in honor of David and Marilyn Kirk, colleagues of Ferris with whom he originally began studying Volvox sex determination at Washington University. The Kirks played a major role in turning another Volvox species, V. carteri, into a model molecular genetic system.
The discovery came with impeccable timing: Now a research associate in Richard Michod’s lab in the UA’s department of ecology and evolutionary biology, Ferris was turning his attention to other aspects of Volvox evolution, and needed a model species.
“We’re interested in a broad range of evolutionary questions on this series of increasingly complex species,” Ferris said.
Funded by the National Science Foundation, the team in Michod’s lab is looking at how Volvox genes have changed to determine its evolution over time, continuing a line of research that began with the description of a species of Volvox in 1700 by Anton van Leeuwenhoek, the inventor of the microscope.
“He described the Volvox life cycle more than 300 years ago, and probably in a species that’s related to V. ferrisii,” Ferris said. “So we knew that we needed to look at a member of that group.”
The team is now investigating several Volvox species, Ferris said, including V. ferrisii. “V. ferrisii had recently come out of the wild and was growing really well, and it’s a healthy strain,” Ferris said. “I didn’t think about anything else in choosing to study it. Well, maybe I did think about the name.”
The denouement? Said Ferris: “I’m studying my own organisms.”