I’m no biologist, but I’m pretty sure this ignores how fluid the evolution is from regular bird to proto-chicken to chicken.
Not really there is a well defined line that defines what is/isn’t a chicken, that’s really the only thing needed for this question.
The issue is the term proto-chicken isn’t well defined.
But for it to be considered a different species it would have to not be able to reproduce with a modern chicken (which doesn’t mean it can’t reproduce with early chickens).
there is a well defined line that defines what is/isn’t a chicken
You’ll have no problem citing the exact definition then.
The chicken (Gallus gallus domesticus) is a domesticated form of the red junglefowl (Gallus gallus), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is one of the most common and widespread domesticated animals in the world. Chickens are primarily kept for their meat and eggs, though they are also kept as pets.[1]
The red junglefowl (Gallus gallus), also known as the Indian red junglefowl (and formerly the bankiva or bankiva-fowl), is a species of tropical, galliform bird in the phasianid family, found across much of Southeast and parts of South Asia.
en.wikipedia.org/wiki/Red_junglefowl
A species (pl. species) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. It can be defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction.
The first two links are irrelevant because they describe physical characteristics and not a well defined line. The quotes you copied are vague descriptions at best.
The last quote you emphasized says “it can be defined” which shows it’s not a well defined line. Also, there are quite a few cross-species hybrids that have produced fertile offspring.
African forest elephants and African bush elephants are known to hybridize with each other where their ranges overlap.[17] Evidence shows that they can form hybrid zones where their ranges overlap, particularly in the Democratic Republic of Congo and Uganda. Hybrids have been found to be fertile, and a significant number of elephants in hybrid zones, such as Kibale National Park in Uganda, show intermediate physical characteristics.
These birds aren’t even in the same family and have hybridized
The red-crested cardinal (Paroaria coronata, family Thraupidae) has hybridized between the northern cardinal (Cardinalia cardinalis, family Cardinalidae), shiny cowbird (Molothrus bonariensis, family Icteridae), and chestnut-capped blackbird.
The concept of a species is a lot more flexible and less-defined than you think.
howrar@lemmy.ca 9 hours ago
By the well ordering theorem, no matter what you choose as your definition of “chicken”, there must be a first.