The editor’s choice for our January issue is ‘Environmental filtering of life-history trait diversity in urban populations of Arabidopsis thaliana‘ by Gregor Schmitz et al. Here, Associate Editor Richard Shefferson discusses the importance of this research:
One of the more common motifs that Hollywood sets to the screen is the story of the country boy or girl moving to the city, and finding life there dark, fast, and confusing. Sometimes staged comedically, as in Eddie Murphy’s Coming to America, and other times tragically, as in Michael J. Fox’s Bright Lights Big City, such movies show the city as another world altogether, and this world comes with enormous stresses that select out those who don’t belong. Is there some ecological truth to this idea?
Cities present unique challenges to the life that calls them home. But cities are not sterile – life finds its way into the cracks of even the toughest pavement. We know that life seems to adapt in similar ways to cities, regardless of location on the planet. This appears to be due to common patterns in environmental filters and natural selection, which can even lead to similarities in life history traits in certain species across cities all over the globe (Santangelo et al. 2022). For example, many animals have adapted behaviorally to city life, including raccoons, raccoon dogs and foxes, pigeons, and crows (McDonnell & Hahs 2015; Santini et al. 2019).
In this issue, Schmitz et al present an eye-opening study exploring the ecological and adaptive context of urban plant evolution. They collected Arabidopsis thaliana seed from a range of urban environments in the area of Cologne, Germany. They then assessed the phenotypic and genetic diversity of a range of important life history traits. They found both phenotypic and genetic variation in these traits, and that this variation was correlated to existing gradients in environmental conditions. Further, the genetic variants identified represented a subset of the genetic variation identified across a larger area in the sampling zone, with typically one or two clones per site. These genotypes corresponded to non-random combinations of life history traits across the sampling zone. All of this suggests environmental filtering of genotypes by cities, and selection leading to distinct patterns of local adaptation.
Some of the genetic variation identified was associated with disturbance regime. For example, more heavily disturbed sites were associated with later flowering genotypes that produced more fruits. However, these same genotypes flowered earlier in common gardens, in which disturbance could be controlled for. Results such as these suggest that life history traits may evolve in ways that buffer populations against the effects of the large levels of environmental heterogeneity among city environments (for example, soil conditions and humidity gradients).
Among the more interesting observations that Schmitz et al yield, then, is that cities are not environmentally monotonous from the point of view of urban plant populations. However, the environmental heterogeneity that we find in cities may select for phenotypes that, in situ, appear similar. It is only through common garden studies such as this that these genotypic differences can be observed. And in such circumstances, we can ponder whether cities are stressful to all life that experiences them, or whether some species find them as full of opportunities as so many people do.
Read the full article online: Environmental filtering of life-history trait diversity in urban populations of Arabidopsis thaliana
Literature Cited
McDonnell, M.J. & Hahs, A.K. (2015). Adaptation and adaptedness of organisms to urban environments. Annual Review of Ecology, Evolution, and Systematics, 46, 261–280.
Santangelo, J.S., Ness, R.W., Cohan, B., Fitzpatrick, C.R., Innes, S.G., Koch, S., et al. (2022). Global urban environmental change drives adaptation in white clover. Science, 375, 1275–1281.
Santini, L., González-Suárez, M., Russo, D., Gonzalez-Voyer, A., von Hardenberg, A. & Ancillotto, L. (2019). One strategy does not fit all: determinants of urban adaptation in mammals. Ecology Letters, 22, 365–376.
Schmitz, G., Linstädter, A., Frank, A.S.K., Dittberner, H., Thome, J., Schrader, A., et al. (2024). Environmental filtering of life-history trait diversity in urban populations of Arabidopsis thaliana. Journal of Ecology, 112, 14–27.
