When it comes to genes, more is better for nettles. Researchers in the Czech Republic have found that Urtica dioica, the common nettle, can occupy a broader range of habitats when it has four copies of its genome instead of the usual two.
While it might seem that all nettles sting the same, the results support the idea that polyploidy, carrying extra copies of the genes, gives plants more flexibility in tackling novel environments. In their paper, Tomáš Urfus and colleagues write: “[T]he results have important implications for environmental niche modelling and associated species distribution models. These extremely popular methods assume that species are ecologically homogenous entities and therefore occurrences recorded at the species level can be used to model a species environmental niche and project this niche into geographical space in order to predict a species distribution… However, our results clearly show that this crucial assumption is invalid even for one of the most common vascular plant species. Although the frequency of intraspecific variability in ecological preferences is unknown, our results clearly show that environmental niche modelling must account for within-species variability in order to produce better distributional models.”
The team used flow cytometry to examine the cells of nettles collected from several different locations around Moravia. This method passes cells one by one in front of a laser. By the way the light is scattered, it’s possible to deduce what is inside the cell, including how many copies of its genome it has.
Many organisms, including humans, have pairs of chromosomes, meaning they have a genome inherited from either parent. But some organisms, particularly plants, can carry three to eight copies of their genes inside their cells.
In the case of the nettles, the botanists found that the diploid nettles that had just the two copies of genes preferred damp conditions. However, when the plants were tetraploid, carrying four copies of their genes, they were more capable of living in dryer and disturbed habitats. The disturbed element means that the nettles you see in your garden are more likely to be tetraploid.
The findings could help model how plants expand their ranges and escape their ancestral niches.
Urfus, T., Kopecký, M., Urfusová, R., Chrtek, J., 2021. Whole genome duplication increases ecological niche breadth of the perennial herb Urtica dioica. Preslia. https://doi.org/10.23855/preslia.2021.305