ZME Science
No Result
View All Result
ZME Science
No Result
View All Result
ZME Science

Home → Science

Scientists discover algae with three sexes

The research could help scientists understand how different sexes evolved in the first place.

Tibi PuiubyTibi Puiu
July 14, 2021
in Biology, News, Science
A A
Share on FacebookShare on TwitterSubmit to Reddit
Left: Sexually induced male colony of algae. Center: Pleodorina starrii female colony with male sperm packet (arrowhead). Right: Pleodorina starrii female colony with dissociated male gametes (arrowheads). Scale bar = 50 micrometers. Credit: Kohei Takahashi.

For more than 30 years, Hisayoshi Nozaki had been studying algae samples from freshwater systems close to Tokyo. But even he, an associate professor at the University of Tokyo with extensive experience studying algae, was surprised to find a new species that evolved three different sexes, which can breed in pairs with each other. It’s the first time that such an alga has ever been found.

When two sexes are just not enough

The earliest lifeforms that evolved on Earth billions of years ago reproduced asexually — essentially cloning themselves. Later, some organisms evolved sexual reproduction, which requires two parents to each contribute a gamete (sex cells like sperm and eggs) in order to produce offspring with unique genetic characteristics.

Both modes of reproduction have their pros and cons, but how exactly this transition took place is not very well understood.

Some organisms are hermaphrodites, being equipped with both male and female reproductive organs due to very unusual gene expression. However, the new kind of green algae found by Nozaki, known as Pleodorina starrii, is no hermaphrodite. It has three distinct sexes: male, female, and a third sex that the Japanese researchers call bisexual in recognition of the fact that it can produce both male and female sex cells (but with normal expression of genes unlike hermaphrodites).

“It seems very uncommon to find a species with three sexes, but in natural conditions, I think it may not be so rare,” said Nozaki.

For Nozaki, the peculiar algae found in Lake Sagami and Lake Tsukui are of great interest. They may help scientists uncover how early primitive organisms evolved into individuals that sexually reproduce.

In normal conditions, P. starrii grow into spherical colonies composed of 32- or 64-celled organisms that have small mobile (male) and large immobile (female) sex cells. Male colonies are recognizable by the packets of sperm they release into the water. These sperm swim until they encounter a female colony, where they combine with the female cells to produce a new generation.

But during new experiments, the Japanese researchers separated P. starrii colonies into male and female and then deprived these isolated colonies of nutrients. In isolation the colonies reproduce asexually, forming clones with the same genotype. If they’re separated and deprived of nutrients at the same time, the colonies are forced to reproduce sexually.

RelatedPosts

Algae have proteins that are really good for your muscles
Photosynthesis could be as old as life itself
Green ice spotted in Antarctica’s Ross Sea triggers new expedition for April
Climate change is making the Arctic red — and we should be very worried about it

The researchers found that some P. starrii individuals have bisexual-factor genes that produce normal male or female colonies when they reproduce sexually with other P. starrii colonies. Genetically male P. starrii have only the OTOKOGI male-type gene (a Japanese word meaning “manly”) and genetically female algae can have either only the female-type HIBOTAN genes or both HIBOTAN and the bisexual-factor genes. The researchers suspect that the bisexual factor may only be active in the presence of the “manly” OTOKOGI.

Although algae are very different from humans, this investigation may allow scientists to gain a better grasp of the ways that evolution shape different sexes we recognize as male or female in our own species.

“This finding was possible because of our very long-term experience of going on field collection trips and our practice growing and studying algae. Continued, long-term studies are very important to unveil the true nature of species in the natural world,” Nozaki commented.

The findings were published in the journal Evolution.

Tags: algae

ShareTweetShare
Tibi Puiu

Tibi Puiu

Tibi is a science journalist and co-founder of ZME Science. He writes mainly about emerging tech, physics, climate, and space. In his spare time, Tibi likes to make weird music on his computer and groom felines. He has a B.Sc in mechanical engineering and an M.Sc in renewable energy systems.

Related Posts

Biology

Scientists find giant viruses on Greenland ice. Here’s why this is actually a very good thing

byTibi Puiu
11 months ago
Science

Algae have proteins that are really good for your muscles

byMihai Andrei
1 year ago
The yellow sotted salamander. Image credit: Brian Gratwicke.
Amphibians

The yellow-spotted salamander: the only known solar-powered vertebrate

byElena Motivans
2 years ago
Environment

Researchers report a steady increase in the intensity of algal blooms over the last 30 years

byAlexandru Micu
3 years ago

Recent news

Ancient British Miners Shipped Tin All the Way to the Pharaohs

May 13, 2025

The UK just trained a health AI on 57 million people to predict disease

May 13, 2025

AI and Brain Scans Reveal Why You Struggle to Recognize Faces of People of Other Races

May 13, 2025
  • About
  • Advertise
  • Editorial Policy
  • Privacy Policy and Terms of Use
  • How we review products
  • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.

No Result
View All Result
  • Science News
  • Environment
  • Health
  • Space
  • Future
  • Features
    • Natural Sciences
    • Physics
      • Matter and Energy
      • Quantum Mechanics
      • Thermodynamics
    • Chemistry
      • Periodic Table
      • Applied Chemistry
      • Materials
      • Physical Chemistry
    • Biology
      • Anatomy
      • Biochemistry
      • Ecology
      • Genetics
      • Microbiology
      • Plants and Fungi
    • Geology and Paleontology
      • Planet Earth
      • Earth Dynamics
      • Rocks and Minerals
      • Volcanoes
      • Dinosaurs
      • Fossils
    • Animals
      • Mammals
      • Birds
      • Fish
      • Amphibians
      • Reptiles
      • Invertebrates
      • Pets
      • Conservation
      • Animal facts
    • Climate and Weather
      • Climate change
      • Weather and atmosphere
    • Health
      • Drugs
      • Diseases and Conditions
      • Human Body
      • Mind and Brain
      • Food and Nutrition
      • Wellness
    • History and Humanities
      • Anthropology
      • Archaeology
      • History
      • Economics
      • People
      • Sociology
    • Space & Astronomy
      • The Solar System
      • Sun
      • The Moon
      • Planets
      • Asteroids, meteors & comets
      • Astronomy
      • Astrophysics
      • Cosmology
      • Exoplanets & Alien Life
      • Spaceflight and Exploration
    • Technology
      • Computer Science & IT
      • Engineering
      • Inventions
      • Sustainability
      • Renewable Energy
      • Green Living
    • Culture
    • Resources
  • Videos
  • Reviews
  • About Us
    • About
    • The Team
    • Advertise
    • Contribute
    • Editorial policy
    • Privacy Policy
    • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.