Yeah, canadensis is univoltine and an obligate diapauser. They need winter to break diapause and have a second generation.
I suspect the late flight showed up in your region circa 2000 due to climate change. It’s about the same time cresphontes really expanded northward into Ontario and Quebec, which we chatted about earlier. Prior to that, cresphontes was pretty rare here. Now they are abundant.
Post by exoticimports on Oct 23, 2020 3:30:19 GMT -8
eurytides I thought some of the info in the paper would be new to you, but since you've read it, clearly your observations/ info includes the discussions presented in the paper.
So is the late flight in Vermont MST?
Both Hagen and Scribner (early 1990s) call the Finger Lakes (plus) region a "hybrid zone" with high levels of canadensis inbred; not surprisingly, this coincides with the all-yellow population (though at first I took this to mean MST before MST was recognized.) That said, when I've broached the topic, as I read it, you believe this population to have some archaic canadensis, but not really a 50/50 hybrid??
I just find the situation odd, aside from the question what is and where is MST. We have an all-yellow "race" boxed in by canadensis, apparently appalachiensis, and the dark female "race"; this all-yellow race has been, for decades, noted as being odd/ unusual/ questionably a hybrid. Yet, I see not much in the way of genetic and other studies done to compare it to the nominate dark female group to discern if it is a distinct ssp or race.
I find it interesting, since apparently I'm in the hotbed of all this, with arguably four different Tigers within a 2.5 hour drive.
Well, it's been a while and I'm sure some of the stuff in the paper would be new to me but I do recall the general ideas of the article.
MST is such a new concept. I don't think we know its range of if it's "one thing" or multiple. I would guess Vermont has MST. My understanding of the situation is that the tigers you see in May and June are glaucus with some genetic introgression from canadensis. I think this was discussed in a paper earlier in the thread. This is why spring form glaucus has canadensis-like features. The false second generation, or MST as we call it now, is the non 50/50 weird mix of canadensis and glaucus. I don't think it's 50/50 because it clearly occurs in areas where no F1 is possible because there is no glaucus. Like, you can see them in the Ottawa region in Ontario, and glaucus definitely isn't that up north. Where are the glaucus parents to provide the 50%?
I'm unsure if the "yellow race" glaucus coincides exactly with the region where "spring form" glaucus occurs. If so, the lack of the melanic females is likely due to some gene flow from canadensis as well as lack of mimic models up north (like Limenitis arthemis astyanax). I think one of the previous papers posted in this thread also addressed that. Now, the question is, does that make it a subspecies? Here, it depends on your personal preference. I think because this trait is clinal, most legit taxonomists would hesitate to say it's a different race. Color morphs also have no taxonomic status under current nomenclature rules as I understand them.