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Plants adopt new strategies to survive in cities | |
admin | |
2022-06-20 | |
发布年 | 2022 |
语种 | 英语 |
国家 | 法国 |
领域 | 地球科学 ; 资源环境 |
正文(英文) |
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A seven-spotted ladybird on a lavender flower, in a park in Neuchâtel, Switzerland.
Whether between paving stones, on the edges of pavements, or along walls, wild plants are surreptitiously settling in cities. They can even adapt to the urban environment through genetic evolution, explains the ecologist Pierre-Olivier Cheptou.
Is it true that wild plants, faced with the destruction of their natural habitat, are increasingly present in cities? Despite this, it would be a mistake to think that urban environments are the solution to conservation problems! In France, farmland makes up most of the available surface. Yet it has lost 75% of the insect biomass over the past thirty years. The reason why we think wild species are on the rise in urban areas today is probably that our perception of cities has changed. In fact, wild plants have always been there. We just weren't aware of them, since cities were mostly seen as unnatural places. How do plants adapt to the urban environment? ![]() We came to this conclusion by comparing specimens of Crepis sancta from beneath street trees with populations from the countryside of Montpellier, a few tens of kilometres from the city centre. This species produces two types of seed: small ones that are easily blown away by the wind, and large ones that fall closer to the plant and are not dispersed. In the city, the proportion of large seeds has increased to 15% of the total, as compared to 10% in rural areas. The change we observed took place over fifteen generations, in other words in the space of fifteen years, since this is an annual plant. This is an example of what is known as rapid evolution, a phenomenon only discovered in the last thirty years. In his version of evolution by natural selection, Darwin didn't believe that such rapid adaptation was possible. Is the evolution of species always good news? ![]() I also study the effect of pollinator decline on plant pollination systems. We hypothesise that, in order to survive, plants adapt by doing without pollinators and making use of self-fertilisation (since they are generally hermaphrodites). There is evidence of a breakdown in the interaction between plants and pollinators due to an increase in the plants' self-fertilisation rate. This is a very worrying trend, because if the right sanitary conditions for pollinators are met in agricultural environments, the plants may not provide them with enough nourishment. It means that the relationships within the ecosystem are changing. Moreover, while a higher rate of self-fertilisation can save plants in the short term, it is not necessarily good for their survival over time. On evolutionary scales, species that adopt self-fertilisation systems have never had a very bright future. Such a strategy could therefore be their undoing. You explain that studying the adaptation of plants in urban environments is highly instructive from a more global point of view. Cities can also help shed light on other ecosystems affected by habitat fragmentation, and this reflects many natural situations. For example, there are similarities between Crepis sancta in their urban grass patches, and observations of island flora by botanists in the 1960s. Admittedly an island is much larger, but the situation is the same regarding seed dispersal: if they spread too far, they fall into the water. So plants are likely to disperse less. How can cities become more wildlife-friendly? Footnotes
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来源平台 | CNRS News |
文献类型 | 新闻 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/348457 |
专题 | 地球科学 资源环境科学 |
推荐引用方式 GB/T 7714 | admin. Plants adopt new strategies to survive in cities. 2022. |
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