Ability to self-fertilize helps plants to spread around the world
A study led by ecologists from the University of Konstanz, Mialy Razanajatovo and Mark van Kleunen, with participation of two researchers from the Institute of Botany, The Czech Academy of Sciences, Petr Pyšek and Jan Pergl, shows that plants able to produce seeds without mates or pollinators are more likely to naturalize outside their native range, and thus can spread more easily around the world. The results of the international collaboration project, that further included researchers from German Centre for Integrative Biodiversity Research (iDiv), University of Göttingen, University of Vienna and University of Durham were published in the prestigious journal Nature Communications on 31 October 2016.
More than 13,000 plant species have, due to humans, spread outside their original geographic ranges, where they now grow and reproduce in the wild. As some of these naturalized alien species threaten native biodiversity, there is large interest in finding plant traits that drive the naturalization of alien species. So far, only few traits universally associated with naturalization success have been detected. For this project the researchers extracted quantitative data from so-called breeding-system experiments on the ability of plants to self-fertilize. Data for a total of 1,752 plant species were combined with data on naturalized plant species from the Global Naturalized Alien Flora database (GloNAF), compiled by the authors of the present paper in 2011–2015 (see van Kleunen et al., Nature 525:100–103, 2015).
Most plants are hermaphroditic, which means that they have both male and female reproductive organs, allowing for self-fertilization. Selfing ability is more prevalent among short-lived plants that reproduce only once in their life time than among long-lived plants, and might also positively affect the size of a species’ native range. Both longevity and native range size might also affect naturalization success. This makes it difficult to determine the actual influence the selfing ability has on the probability that a species would naturalize.
A novel aspect of the study by Mialy Razanajatovo and colleagues is that they could clearly identify if there is a direct or indirect relationship between a plant’s selfing ability and its naturalization success. “If the relationship between a plant’s selfing ability and its naturalization were only indirect, the selfing ability would not determine the ability to naturalize and would therefore not be a suitable characteristic to determine the naturalization potential of a plant, and associated risks from it possibly becoming invasive,” explains Mark van Kleunen, the senior author of the study. The study revealed that the apparent relationship between a plant’s selfing ability and whether or not it has naturalized somewhere in the world outside its native range is statistically completely mediated by longevity and native range size. The size of the global naturalized range is, however, also directly driven by the selfing ability. “Therefore, a high selfing ability make the plants less dependent on the presence of mates and pollinators, and thereby allows them to establish in many regions,” concludes Petr Pyšek from the Institute of Botany, The Czech Academy of Sciences, and one of the GloNAF database founders.
Hedychium gardnerianum is an example of a plant with a high selfing ability naturalized in many regions. Photo by M. Hejda
Razanajatovo M., Maurel N., Dawson W., Essl F., Kreft H., Pergl J., Pyšek P., Weigelt P., Winter M. & van Kleunen M. (2016) Plants capable of selfing are more likely to become naturalized. Nature Communications 7: 13313.
Contact: prof. RNDr. Petr Pyšek, CSc. (pysek_at_ibot.cas.cz, tel.: 271015266)