Reindeer Lichens Are Having More Sex Than Imagined

Reindeer lichens — named for their notable place in a reindeer’s balanced diet — are reproducing sexually at a rate that far exceeds what scientists would have ever guessed.

Microscopic view of reproductive organs of reindeer lichens (Credit: Kim Daloise)

(CN) — Reindeer lichens, beloved by wild reindeer looking for an easily grazeable meal, generally find it easiest to reproduce asexually by simply cloning themselves instead of the more energy-intensive affair that is sexual reproduction. Now, however, research suggests reindeer lichens are actually having sex. A lot of sex.

Researchers suggest these findings could likely play a role in conservation efforts going forward, as it could help guide the decision-making process for what areas and elements of a forest get special protection priority.

In the northern wilds of Canada, one would be hard pressed to find a forest floor not blanketed by a thick layer of reindeer lichens. The common observer would likely look upon them and see little more than small, mossy clumps comprised of tiny interweaving branches, but such an observation would be a gross undervaluation of the complexity and importance these small specimens actually command.

Reindeer lichens are highly unusual composite organisms, made up of both a type of algae and type of fungus that have evolved to live as a single entity and are, as their name implies, a tremendously important part of most reindeers’ diet. They are also highly adaptable in the kind of climates they can thrive in, with many in the Northern Hemisphere being some of the most cold-resistant fungi in their ecosystems.

Now, researchers have uncovered a new detail that further demonstrates just how complex and often surprising these organisms can be: they are also having sex at a shockingly aggressive rate.

In a study published Friday in the American Journal of Botany, researchers took a deep dive into the genetic diversity of reindeer lichens to see what kind of genes were or were not being mixed among reindeer lichens populations, and were surprised to discover that they have been breeding with each other at a level researchers would have likely never anticipated.

This shock stems from the fact that, like many fungi and algae, reindeer lichens have two main ways to reproduce: sexually and asexually. 

While the lichens can reproduce sexually by using their roots to find a partner and swap genetic information, thus creating a spore that travels on the wind and later grows into offspring, this process can be energy consuming and quite difficult. 

While there are certainly some benefits to producing sexually, such as by creating offspring with stronger, more durable genetic traits, the risk it entails pushes most reindeer lichens towards reproducing asexually, in which they essentially pinch off a part of themselves that independently grows to become a virtual clone of the original.

Despite the tougher realities of sexual reproduction, however, reindeer lichens seem to be doing it quite a lot anyway. When researchers used advanced sequencing technology to examine the DNA of a number of the lichens from Northern Canada, they found a surprisingly strong amount of genetic diversity among the lichens, suggesting sexual reproduction is being utilized far more frequently than they thought.

Marta Alonso-García, lead author of the study and postdoctoral fellow at Quebec’s Université-Laval, says that these findings fly directly in the face of researchers’ previous understanding of reindeer lichens and their reproductive tendencies.

“We were surprised because this species of reindeer lichen had always been considered mainly a clonal species that reproduces asexually,” Alonso-García said in a statement. “It doesn’t follow the expected pattern.”

Researchers say that on top of being an unexpectedly surprising look into how reindeer lichens are reproducing, Friday’s findings also shed some interesting light on how the lichens reform and recover in the aftermath of a forest fire, an event that can decimate populations of fungi and algae.

But it was here as well that researchers made some observations that seemed to openly defy previous expectations. Experts suspected that after reindeer lichens returned to the forest, they would be genetically different than the ones that thrived before the fire. In reality, they found that the post-fire lichens were remarkably similar on a genetic level to the pre-fire lichens.

Felix Grewe, co-director of the Field Museum’s Grainger Bioinformatics Center and a co-author of the study, said that on top of the fascinating results that Friday’s study uncovered, the effort should serve as but another reminder on just how deep researchers can delve into the genetic mysteries on Earth’s creatures using the powerful tools of modern technology.

“It is astonishing that today we can have such a detailed view of the evolution of populations using bioinformatics,” Grewe said. “This is another good example of how advancement in sequencing technology allows us to learn about the evolution of an organism in more detail than ever before.”

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