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h3rbi74 t1_j01e4v4 wrote

There is a TON of lateral gene flow (ie crossbreeding) between some populations of canines. Not just domestic dogs and “gray wolves” in general, but also coyotes and some particular geographic subspecies of wolf. “What constitutes a species” isn’t nearly as cut and dried as we were led to believe back in the day, when part of the definition included not reproducing with another species! One example of a trait that most researchers agree originated in dogs is melanistic/black wolves found in Yellowstone and some other places. I can’t remember which specific paper we talked about when I first learned about this in a seminar by Ray Coppinger many years ago, but here are a couple that come up on a quick search to get you started:

https://www.sciencedirect.com/science/article/pii/S0960982218311254

https://www.nature.com/articles/s41586-022-04824-9

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horsetuna t1_j058spn wrote

Randomly on the topic of what defines a species, they found that two species of cichlid fish will interbreed and produce viable offspring if you use a filtered color of light that makes them look identical. .

But in natural conditions, they will refuse to even approach each other because they look too different.

A similar study was done on two species of grasshoppers. The females breed with the males that sound right. And each species female has a different note that means 'this male is my species'.

But the notes the males sing at depends on their temperature! The put heaters on the heads of grasshopper A and made them sing at the note for Grasshopper B species... And the females accepted the warmed up males. I don't remember if the offspring were viable though

(Also they found where the two grasshopper species overlap, there was a bigger difference between their songs. But further apart the songs actually sounded more similar, where the risk of cross breeding was smaller)

Species are weird, fluid, and artificial. And also what is 'natural conditions '? In the wild, the cichlids and grasshoppers would probably never cross breed unless a mutation broke down the barrier.

It makes you think what is a 'natural' environment for a human. We have interned with Neanderthals, so we cannot be a distinct species from them... Or did we put ourselves and them into artificial, unnatural conditions when we broke down language and cultural barriers? Yes there could have been force involved... But iirc no other species forces itself on other species (except perhaps dogs and amorous pet cats, which can be because of a lack of natural releases or abnormal breeding causing these issues)

It can become a controversial and even DANGEROUS thing especially when you apply such discussions to humans, who are ever the exception to the rule of nature.

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