Pollination is the hallmark of flowering plants, where animal pollinators like bees and birds maintain the world’s food supply—not to mention our cravings for coffee, honey, and macadamia nuts. But new research raises the possibility that animal-assisted pollination appeared at sea, long before plants moved ashore.
The study, conducted by research groups based in France and Chile, is the first to document a type of seaweed that relies on small marine crustaceans encrusted in pollen-like spores for reproduction.
Since red algae Gracilaria gracilis The researchers say their study developed long before the emergence of land plants, as the study showed that animal-assisted pollination could have arisen about 650 million years ago in the oceans once a suitable pollinator appeared.
On the ground in the seed thriving plants And the Gymnospermsmale reproductive cells, or gametes, fly in the form of pollen, which is carried by wind, through water, or by surprise insects, hoping to land on their female counterpart somewhere far away.
Then the scholars Discover that algae (A type of rootless, non-flowering plant classified as bryophytes) and some fungi also use animals and insects to facilitate reproduction, making what they know about animal-mediated pollination.
Although it is often discussed, researchers believe that it originated in concert with terrestrial plants About 140 million years ago – or at least during the Mesozoic Era, which extends to approximately 252 million years ago.
Only a few years ago, scientists discovered that marine invertebrates carrying sperm from seaweed feed on them, throwing into the sea the ancient theory that oceans are devoid of pollinators.
Now, this new study from Emma Laffaut, a graduate student in evolutionary biology at the Sorbonne University in Paris, and her colleagues, describes how small crustaceans are called isopods, Idotea Balthicahelp fertilize a kind of red seaweed, G. Graciliswhich evolved about a billion years ago, long before 500 million years ago When wild plants appeared.
“The study by Lavaut et al.. extended the diversity and history of male gamete transfer mediated by animals, taking the concept of insemination from [land] plants to algae and possibly pushed them to the earliest evolution of marine invertebrates,” Type Jeff Ollerton and Zhong Shen Ren, ecologists at the Kunming Institute of Botany of the Chinese Academy of Sciences, in perspective attached to the paper in Sciences.
A type of algae that performs photosynthesis, seaweeds are very distantly related to the so-called true plants.
G. Gracilis It also differs from most other seaweeds in that the male gametes do not have a flagellum to propel them through the water, and are left adrift in the ocean – unless they can cut through a ridge on a passing creature, as this new work suggests they often do .
In a series of laboratory experiments, Laffaut and colleagues showed how small marine isopods, which feed along male filaments. G. Gracilisinadvertently collect male gametes from seaweed (sperm) as you do, and transfer them to female plants.
In the photo below, you can see a motif decorated with light-stained sperm, which indicates that crustaceans may be serving as pollinators.
“Our results demonstrate for the first time that biotic interactions significantly increase the likelihood of fertilization in a seaweed,” Laffaut and colleagues Type.
The success of fertilization was about 20 times higher in the presence of First Balthika Without the creatures, the team found.
But they have not yet compared this pollination of crustaceans with the dispersal of pollen along water currents to see which plays a greater role.
The origins of plants using animal pollinators remain wide open, considering that researchers only inferred based on the evolutionary history of the animals involved.
Laffaut and his colleagues believe that seagrass provides abundant habitat, shelter, and food for grazing ideas. In contrast, not only small crustaceans help G. Gracilis They reproduce, but their appetite for parasite-like plants is colonizing G. Gracilis Researchers have found that fronds actually boost the growth rates of seaweed.
However, in a world marked by rapid human-caused climate change, these delicate interrelationships between plants or algae and animals are threatened as much as the ecosystems that sustain them.
seaweed like G. Gracilis Relying on stagnant coastal waters for reproduction, when coasts are exposed to storms and sea levels rise slowly toward land. Meanwhile, ocean acidification can weaken crustacean exoskeletons – although this needs to be studied in isopods.
While the threat of global warming is very clear, evolutionary-minded ecologists are still confused G. Gracilis did before First Balthika Appearing on the scene, isopods are not as old as algae, they evolved only 300 million years ago.
Although they likely depended on ocean currents, “how these seaweeds reproduced before this is still a mystery” explain Olton Wren.
If science has taught us anything, we should always prepare ourselves for more surprises. Recent estimates from Ollerton indicate that one-tenth of the more than 300,000 known species of flowering plants that pollinate animals have been documented as pollinators.
So what types are working their magic? “There is no doubt that many discoveries await the careful observer of species interactions,” Ollerton Wren deduce.
The study was published in Sciences.