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A second issue is that, at lower levels, taxonomy isn’t a very well defined thing. (Perhaps one way to think of it is that phylogeny maps onto taxonomy and this

A second issue is that, at lower levels, taxonomy isn’t a very well defined thing. (Perhaps one way to think of it is that phylogeny maps onto taxonomy and this mapping isn’t injective.) So if two groups of animals are reclassified as two species, it is hard to say whether or not a new species was discovered. Especially if the two variants were known before—should one backdate the species discovery to the time the variants were identified? Similarly, a species doesn’t really go extinct if the taxonomy changes so two species are merged into one. The vernacular names for some group of animals (or plants) needn’t correspond to some clade that gets a taxonomical name. Eg broccoli and cabbage are considered the same species, whereas ‘crab’ may refer to all sorts of largely unrelated animals.

akiselev 6y ago
> The vernacular names for some group of animals (or plants) needn’t correspond to some clade that gets a taxonomical name. Eg broccoli and cabbage are considered the same species, whereas ‘crab’ may refer to all sorts of largely unrelated animals. Broccoli (Brassica oleracea var. botrytis) and cabbage (var. costata/italica) are bad examples [1], since subspecies and varieties are well defined as ranks in botanical taxonomy and there are regulatory structures based on them. I think a better example would be hybrids like plumcots which are crosses of multiple species. Fitting them cleanly into natural taxonomy is a huge mess - over evolutionary timescales hybrids usually outcompete, converge with, or diverge from their parents enough to clean up their taxa for us. [1] https://plants.usda.gov/core/profile?symbol=brol https://plants.usda.gov/core/profile?symbol=brol - Subordinate Taxa tab