> 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.
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 - Subordinate Taxa tab