Kelp can reproduce asexually when mates are scarce, study finds

A study published on 12 November in PLoS Biology shows that kelp can reproduce without fertilization when potential mates are scarce, according to reporting by Nature.

Reproductive flexibility

Both male and female kelp were shown to be capable of reproduction without fertilization. The researchers focused on Laminaria pallida, a species found along the Atlantic coasts of South Africa and Namibia.

"Our findings highlight that kelp are even more flexible in their reproduction than previously appreciated," says Daniel Liesner, a marine biologist at the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany.

Scientists already knew that kelp can reproduce asexually, with unfertilized eggs developing into offspring. This process was even documented for one male strain. The PLoS Biology study shows that this was not a one-off.

The ability of male reproductive cells to develop without fertilization is striking, says Olivier De Clerck, a seaweed biologist at Ghent University in Belgium. This is because, unlike eggs, sperm cells are small and have few resources to support development.

Laboratory findings

In the wild, 523 individual kelp showed no clear evidence of asexual reproduction. By contrast, both microscopic male and female L. pallida grown in separate laboratory dishes could produce offspring without fertilization. During asexual reproduction, the gene expression in males changed, making them more similar to females.

However, when they were lab-grown in the presence of a member of the opposite sex, kelp favoured sexual reproduction, suggesting they can detect nearby partners through chemical signals.

Why it matters

The brown algae provide food and shelter for marine life. Insights into the reproductive modes of brown algae could help in the fight to protect them in a warming climate, according to the Nature report.

"What’s interesting about the study is that it helps to explain how changes in gene activity allow kelp to reproduce in different ways," says Reina Veenhof, an ecologist at the Scottish Association for Marine Science in Oban, UK. She describes the brown algae as "really weird, they do all kinds of stuff."

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Sources

• nature.com: Who needs sex? Kelp reproduce asexually when no mate is nearby | Nature

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