Ancestors of Volvox algae made the transition from being a single-celled organism to becoming a multicellular colony at least 200 million years ago, during the Triassic Period.
At that time, Earth was a hot-house world whose inhabitants included tree ferns, dinosaurs and early mammals. Previous estimates had suggested Volvox's ancestors arose only 50 million years.
The algae switched to a communal lifestyle in only 35 million years -- "a geological eyeblink," said lead researcher Matthew D. Herron of The University of Arizona in Tucson.
Figuring out how algae made the leap can provide clues to how multicellular organisms such as plants and animals evolved from single cells.
Cooperating successfully is the key, Herron said.
"All the macroscopic organisms we see around us trace back to unicellular ancestors," said Herron, a doctoral candidate in the UA's department of ecology and evolutionary biology. "Each of those groups had to go through a transition like this one.
"We think the early changes in this process were related to cooperation among cells and conflicts among cells -- and finally to the resolution of those conflicts," he said.
The researchers used DNA sequences from about 45 different species of Volvox and related species to reconstruct the group's family tree and determine how long ago the first colonial ancestor arose.
The team's article "Triassic origin and early radiation of multicellular volvocine algae," is in this week's online Early Edition of the Proceedings of the National Academy of Sciences.Herron's co-authors Jeremiah D. Hackett and Richard E. Michod are members of the UA's department of ecology and evolutionary biology. Co-author Frank O.
Aylward was at the UA when the research was conducted and is now at the University of Wisconsin in Madison. The Society of Systematic Biologists and Sigma Xi helped fund the research.
Volvox and its relatives live in freshwater ponds all over the world. Some of the species are unicellular, while others live in colonies of up to 50,000 cells.
Many of the colonial algae species are visible to the eye and appear to be little green spheres rolling through the water. The most complex species have a division of labor -- some cells do the swimming, others do the reproducing.
Although an earlier estimate suggested the algae's ancestors banded together 50 million years ago, Herron wanted to check the estimate using 21st-century genetic and molecular techniques.
In addition to constructing the Volvox family tree, the team determined how long ago the group's oldest common ancestor lived by comparing the amount of genetic differences between species.
One of the earliest traits to evolve is the clear jelly-like substance visible between the cells of the spherical Volvox colonies, Herron said. "We think that stuff is what held the earliest multicellular colonies together."
Banding together in a larger mass can provide protection from predators, he said. "Some things can't eat you if you're bigger."
But producing the goo, called extracellular matrix, takes resources and is one of the costs of cooperation."So now there's a temptation to cheat," Herron said. "Let's say I'm in a four-cell colony. I'm going to let the other three guys make the extracellular matrix, and I'm going to focus on growing and reproducing.
That's the conflict."
Overcoming that conflict is essential to becoming a multicellular organism, he said. The benefits of cheating have to be reduced for the cells to cooperate successfully.
Some traits the team studied are genetic traits that mediate conflict.
Genetic control of cell number is one of those, he said. "If my number of offspring is fixed at four, now there's no reason for me to cheat. I can't have eight offspring when everyone else is having only four."
Herron is now studying whether the size of the colony affects the degree to which there are different types of cells within the colony.Researcher contact:
Further reports about: > Algae > DNA sequence > Triassic Period > Volvox > Volvox algae > colonial algae species > colonial ancestor arose > dinosaurs > early mammals > evolutionary biology > extracellular matrix > geological eyeblink > macroscopic organisms > multicellular colony > multicellular organism > single cells
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering