One afternoon, I browsed the homepage of the leading botanical journal Annals of Botany as usual, and suddenly found an interesting paper "Plant speciation in the age of climate change" (Levin, 2019). The keywords, "speciation" and "climate change" deeply attracted me, and instantly a million related documents, pictures, words, and ideas rushing into my brain, and finally made me immerse in thinking about this fascinating science through the whole afternoon.
If you search for "plant speciation" and "plant extinction" on the Internet, you will get very contrasting results. Most people are more concerned about plant extinction, but not so much about plant speciation. On one hand, it is related with the inclination in news reports/media bias (for example, it is easier for people to pay attention to species extinction, forest destruction and natural disasters, etc.); on the other hand, it is also related to the inconspicuous plant speciation itself. After all, the time scale of the formation of a species is often measured in thousands of years, and sometimes in millions of years. Even the fastest plant speciation, such as plant breeding, which would usually take several decades. In addition, plant breeding is generally targeted at common crops (such as wheat, rice, corn, soybean and potato, etc.), and people do not particularly pay notice to these new evolved plant species/varieties.
But one thing is certain, plant speciation, like plant extinction, is a never-ending biological process. So, in the context of climate change, especially global warming, what are the main plant speciation types? What will our future world look like? Levin has considered and summarized these issues very well. He argues that in the context of climate change, the dominant speciation types are autopolyploid speciation and allopolyploid speciation, whereas speciation due to chromosomal rearrangements, homoploid hybrid speciation, and lineage splitting are not pervasive. In fact, in the past geological periods, such as Palaeocene–Eocene Thermal Maximum (PETM) 55.8 Mya, when the Earth experienced temperatures 5-8 °C higher than those today, during which plants saw accelerated speciation through autopolyploid speciation. Plants' adaptive capacity to abrupt environmental changes through chromosome doubling or whole genome duplication is the most important biological mechanism to avoid the fate of extinction. Therefore, in the Anthropocene, a foreseeable future is that the polyploid will continue to increase. Compared with large-statured trees, herbs and shrubs have more flexible growth strategies and greater genetic variabilities, thus in the future landscape, there may be more and more small-statured plants, especially perennial herbaceous plants.
Based on the relative importance of plant speciation types, I made a conceptual diagram describing the main plant speciation modes in the context of climate change (Fig. 1). This conceptual image looks like a wine bottle, and the wine here is our plant species. I hope to show you this basic plant biology concept in this intuitive way. The commentary article "Dominant plant speciation types. A commentary on: "Plant speciation in the age of climate change"" has been accepted for publication in Annals of Botany (Gao, 2019).
Publishing is not the end, which usually means a beginning of new research. Some more interesting questions emerged during the literature review, such as what is the mechanism of plant speciation? In which areas on the Earth are easier to form new plant species? What are the current ways of plant extinction? In the context of climate change, do plant speciation or plant extinction dominate? At this moment, my brain is burst with another billion documents, pictures, words, and ideas. An opinion/perspective article I am currently working on "Plant extinction excels plant speciation in the Anthropocene" gradually taking shape.
My friends, welcome to the world of explosive new plant species. Let’s drink up this glass of species wine!
Fig. 1. Five main types of plant speciation. Autopolyploid speciation is the dominant type in the context of climate change, followed by allopolyploid speciation, whereas speciation due to chromosomal rearrangements, homoploid hybrid speciation, and lineage splitting are not pervasive. Different colors on the wine bottle correspond to the proportions of the different speciation types.
Gao, J. G. (2019). Dominant plant speciation types. A commentary on: ‘Plant speciation in the age of climate change.’ Annals of Botany, 124(5), iv–vi. https://doi.org/10.1093/aob/mc...
Levin, D. A. (2019). Plant speciation in the age of climate change. Annals of Botany, 124(5), 769–775. https://doi.org/10.1093/aob/mc...
Gennu F. (2019). The future will be short. Botany One, https://www.botany.one/2019/11/the-future-will-be-short/