Researchers from the School of Agriculture and Food Sciences at the University of Queensland and the School of Biology Sciences at Trinity College Dublin have recently discovered that the Ribwort Plantain (Plantago lanceolata) has actively broken the rules of plant ecology. By monitoring populations worldwide, the researchers discovered that the plantain has large degrees of genetic variation in smaller populations that are unaffected by demographic and environmental changes. This breaks the conventional rule of genetic diversity being influenced by population size changes and dispersal.
The plantain has broken the rules of ecology by having large degrees of genetic variation despite not being influenced by changes in population and dispersal. This had made the plantain resistant to climate change and this offers us the opportunity to learn ways to make endangered plant species resistant to climate change.
The global team of 48 researchers established 53 monitoring sites in 21 nations. They tracked plant population changes, counted flowers and seeds, and looked at DNA. The data was gathered from 35 native and 18 nonnative populations comprising 39 nations. Nonnative populations are those that are found in regions where the species was introduced and is not natively found there. Gene simulation models were also used to measure how species survival and fertility would drive genetic diversity in the absence of dispersal.
It was thought that when plants establish in nonnative areas, their ability to adapt and their genetic diversity was influenced by population size changes and dispersal. By this logic, small populations would tend to have little genetic diversity compared to larger populations. However, the relative importance of the above-mentioned factors was poorly understood.
The findings of this study help paint a better picture. Genetic diversity is key to species survival. The researchers discovered that in disconnected populations of the plantain, there was a greater degree of genetic diversity. Long-distance dispersal and repeated introductions by humans have shaped the potential of plantains to adapt. They do not need population changes to overcome environmental constraints. By simply mixing in-population genetic material, they can have the genetic diversity to survive sufficiently. In fact, dispersal of these populations dilutes their genetic diversity.
These results suggest that nonnative populations are not constrained by the same environmental forces as their native counterparts thanks to repeated, long-distance, human mediated introductions. It is this adaptation to environmental pressures by rapid mutation and interbreeding that is driving the increase in genetic diversity. A striking discovery is that the plantain plays by the rules of ecology in its native Europe but not in nonnative regions, which further affirms the claim that it is the adaptation to environmental pressures that is driving these interesting outcomes.
This work now allows us to create models that will help protect plant species from climate change. It also allows us to prevent invasive species from causing extinction in native populations and costing governments billions of dollars. Interestingly, the two are related. By studying how invasive species adapt to new environments we can help native species adapt to climate change. Thanks to the humble plantain, we have a new horizon for battling climate change.
Smith, A. L., et al. 2020. Global Gene Flow Releases Plants from Environmental Constraints on Genetic Diversity. Proceedings of the National Academy of Sciences.
More for information, go to: https://www.pnas.org/content/early/2020/02/06/1915848117