Taxonomy & Evolution

The future will be short in not tall, rather than apocalyptic.

Even the most rapid forms of plant speciation (e.g. crop breeding) occur over multiple years, and natural speciation generally requires tens of thousands, or even millions, of years, whereas species extinction, especially that which results from man-made or natural disasters, can occur instantaneously. This is probably the primary reason that the public is more likely to notice the extirpation or extinction of species than to notice speciation.

Gao 2019

Jianguo Gao tackles Donald Levin’s Plant speciation in the age of climate change, and has a few comments on Dominant plant speciation types.

Gao puts polyploidy into its evolutionary context by looking beyond the Anthropocene. For a comparable event to current times, Gao looks at the K-Pg extinction for guidance. During the fifth mass extinction, for example, which occurred at the end of the Cretaceous, many flowering plants escaped extinction by duplicating their genomes and then evolved into dominant terrestrial plant lineages,” Gao says in his paper.

Gao considers the various kinds of plant speciation, and asked why autopolyploidization, where a plant duplicates its own genome, is the main type of speciation. It’s down to speed. “[A]utopolyploidization can produce new species in as little as one or two generations. Therefore, in some annual herbaceous plants, new species can be produced within 2 years.” The advantage of a major asteroid strike on your plant, if you are part of a plant lineage that survives, is that you can use autopolyploidization to adapt to new conditions rapidly. If this is a planet where the environment is also changing rapidly, then this gives you a major advantage over less adaptable species.

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 colours on the wine bottle correspond to the proportions of the different speciation types. Gao 2019.

Not all speciation will be autopolyploid. Gao notes that allopolyploids, where two plant species add their genomes together to make a new plant, may be even more adaptable than autopolyploids.

Two features that Gao picks up on in Levin’s piece are the importance of climate change, favouring polyploids, and that polyploids tend to be herbaceous plants, “especially perennial ones, which are more adaptable to environmental changes.” This leads Gao to speculate on the landscapes of the future: “…as climate change progresses, we may see more short-statured herbaceous plants as we walk in the countryside.”

%d bloggers like this: