When it comes to reproduction, one type of red algae gets a little help from its friends: marine crustaceans that transport male and female sex cells, like pollen-laden bees whispering between flowers.
The discovery is the first known example of animal-driven “pollination” in algae, researchers report on July 29. Science. Both red algae and crustaceans belong to much more ancient groups than land plants, suggesting the possibility that the form of spawning first evolved in the ocean, hundreds of millions earlier than first thought.
Pollination typically describes the transfer of male sex cells — pollen — to a female flower, usually in the ground. Then in 2016, researchers discovered that various marine invertebrates “pollinate” seagrasses by feeding and moving between gelatinous masses of seagrass pollen that originated from land plants. But nothing similar has yet been confirmed in algae.
Like other red algae; Slender slender The free-swimming male sex has no cells. Called spermatia, its sex cells were thought to be dispersed by the flow of water in the female algae, just as the wind can spread pollen to fertilize certain terrestrial plants.
In the new study, Myriam Valero, a population geneticist at the Sorbonne University in Paris, and her colleagues studied genetics and the combination. G. slender. After collecting While storing samples of algae in laboratory lids, the team observed hundreds of small, oblong crustaceans kept in the tank. This discovery and the similarity of the algae’s sperm to pollen led the team to wonder if the crustaceans help “pollinate” the algae.
In the lab, the researchers placed male and female algae 15 centimeters apart in a pond without moving water. Some lakes were even centimeters long Idotea balticicaa type of isopod crustacean, while others do not. When successful fertilization occurs in the body of the female red algae, it forms a bubble-like structure called a cystocarp. By counting the cystocarps, the team determined how many sperm reached and fertilized the female algae. When isopods were present, fertilization success was about 20 times as high as when they were absent.
The team also decided to tank just female algae and previously exposed male isopod algae. Some of the female algae then gave birth to cystocarps, while many testified that crustaceans — living relatives of pill bugs — combed the sex cells between the algae’s stems. The team further confirmed the role of isopods when they looked at the crustaceans under a high-powered microscope — as bumblebees were showered with pollen, the creatures’ sperm were embedded throughout their bodies.
The discovery suggests that algae may have been among the first organisms to represent animals to grow sex cells.
They were already evidence of animal-driven fertility and budding, just as before the earth-based budding of flowers had evolved. Scorpion flies can pollinate nuts ten thousand years before flowering plants evolved about 130 million years (SN: 11/5/09). Mosses, which are very similar to the first land plants that evolved about 300 million years before flowering plants, can be fertilized by small arthropods. Red algae are probably more than 800 million years old, and complex animal life goes back more than half a billion years. In this way, animal-driven fertilization could have arisen even earlier than scientists realized.
“Such a system dates back to the Precambrian when red algae were present,” says Conrad Labandeira, a paleobiologist at the Smithsonian National Museum of Natural History in Washington, DC. Pollinators were not isopods, but very early arthropod groups.
Water movement still helps G. slender to expand his spermatozoa. But much of the algae fertilization occurs in rocky lagoons at low tide, when the water is calm, Valero says. “We think that the influence of God” Idotea it is important in these conditions. “
For their merits, isopods can be caught by thick algae and cling to their surface for food.
The team now wants to know if other red algae also use animal “pollinators” and if more than one animal partner is involved in the reproduction of the algae.
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