Hybridogenesis, Resistance to Disease, Blood Types, Xenotransplantation . . .

[Flyndaran]

Originally Posted by vicky_molokh

...
(Oh, there's also horizontal S1 and S2 gene transfer involved, but that's another matter that may or may not be relevant to whether they should be classified as a species or not and why.)

* == For whatever genetic mechanism that is applicable to the setting's biology - not necessarily DNA, but whatever is a close analogue.

Horizontal gene transfer has been known to occur between single celled organisms and humans, so I certainly sweat that issue.
Edit: whoops, it looks like I misremembered. The specific example I was thinking of was transfer from oceanic bacteria to Japanese's gut bacteria allowing fuller digestion of seaweeds.

[Anthony]

Originally Posted by vicky_molokh

What part of the definition of a species does it fail to satisfy? If it's not a species, then what do you call it?

Human, most likely; otherwise something we have no real word for (possibly something like some of the virus-initiated cancers). It's not a species because it's incapable of reproduction on its own.

Originally Posted by vicky_molokh

There are no natural pure S1 because despite superficial sexual dimorphism, S1 are incapable of gestation

Aha. So only the males are capable of breeding. It's not clear why females would even exist under those conditions, as they are apparently a genetic dead end.

[Bruno]

Originally Posted by Anthony

Aha. So only the males are capable of breeding. It's not clear why females would even exist under those conditions, as they are apparently a genetic dead end.

??? Bees and ants and so forth do quite well with non-breeding members as a fundamental reproductive strategy.

[Flyndaran]

Originally Posted by Bruno

??? Bees and ants and so forth do quite well with non-breeding members as a fundamental reproductive strategy.

They serve purposes necessary for the colony. What purpose would males that look identical to the other species' males serve? At the very least, female genomes would be under strong selective pressure to up the percentage of females they birth. 50/50 rates would make less than no sense.

[Anthony]

Originally Posted by Flyndaran

They serve purposes necessary for the colony. What purpose would males that look identical to the other species' males serve? At the very least, female genomes would be under strong selective pressure to up the percentage of females they birth. 50/50 rates would make less than no sense.

You have that backwards. The males can impregnate H0 females, the females are incapable of becoming pregnant.

[Flyndaran]

Originally Posted by Anthony

You have that backwards. The males can impregnate H0 females, the females are incapable of becoming pregnant.

Oh right. My goof. Just reverse my issues. If anything, with how tightly conserved female biology is, I'd imagine quite large changes from "human" norms in addition to just failure to gestate.

[Fred Brackin]

Originally Posted by Anthony

You have that backwards. The males can impregnate H0 females, the females are incapable of becoming pregnant.

Not even with the males of S1. By a simple yet practical definition of "species" this would make males and females of S1 members of different species. If it's something like all females of S1 being born with a major reproductive system defect then S1 would not be a _viable_ species.

If I was invoking technicalities I'd have to classify Males of S1 as a sub-species of H0.

[Flyndaran]

If to be a species most members must reproduce with each other producing genetically mixed offspring, then would all those "species" of parthenogenic lizards qualify as thousands of species "lines"?

[vicky_molokh]

Originally Posted by Anthony

Human, most likely; otherwise something we have no real word for (possibly something like some of the virus-initiated cancers). It's not a species because it's incapable of reproduction on its own.

Wait, why? AFAIK purely androgenetic (androgenic) Corbicula molluscs are incapable of reproduction on their own, does that mean they're not a species? Why do they have a species name then?

Also, a huge number of species are incapable of reproducing on their own. For instance, gut bacteria require a human (or other animal) to live, let alone reproduce; viruses don't reproduce without use of giant enemy cells; many species require embryos to be implanted into a member of another species in order to grow up.

Originally Posted by Anthony

Aha. So only the males are capable of breeding. It's not clear why females would even exist under those conditions, as they are apparently a genetic dead end.

S1 females can still 'infect' H0 males with symbiotice gamete-colonies. While the chances are lower than on a direct path, this can nonetheless indirectly result in the gamete-colonies reaching an H0 female.

[vicky_molokh]

Originally Posted by Flyndaran

If to be a species most members must reproduce with each other producing genetically mixed offspring, then would all those "species" of parthenogenic lizards qualify as thousands of species "lines"?

To be a species most definitely doesn't require reproduction to be with anyone else. An overwhelming majority of monocellular species reproduce asexually in the first place. They also sometimes employ horizontal gene transfer between other species and themselves.