Event follow-up (New Technology)

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Thank you for joining us for: New Technology, New Discoveries.

There were a few questions that were not answered during the presentation.

What is “rewilding?” You can find information on the CANA Foundation website HERE. 

Ross MacPhee provided the following responses:

What is the current assessment of the difference(s) between Pleistocene & modern horse? has that changed w/ this or other recent studies?

There are differences, but most of these are size related. That’s an important point, because most of the fossil caballine species recognized for the North American late Plesitocene (some dozens) are simply scaled versions of one another. Upsizing and downsizing usually has some morphological consequences, but these do not by themselves indicate that horse populations at the time were anything other than ecomorphologically variable (i.e., slightly varying because of differing local circumstances) just as widespread species often are today. Size differences do not establish that interbreeding was absent, merely that local populations differed as they probably did in other regards (e.g., coat color) Ancient DNA shows that there were only two major clades, or evolutionary groupings, of horses in the late Pleistocene of North America. These were the caballine horses, chiefly represented by what we call Equus caballus today, and so-called stilt-legged horses, which are divergent and are grouped in their own genus Haringtonhippus. This genus has completely disappeared. 

Another important point is that the Bering Land Bridge was a major bisectional faunal corridor. In addition to mammoths and bison using it to enter North America, caballines used it to leave the continent for Asia. But relations continued. Vershinina et al (2019) showed that admixture or hybridization continued in both directions, as indicated by the presence of North American markers in Russian fossil horses and vice versa. If contact continued, there is no basis for asserting that they had split and were now different species. 

Have they already sequenced a high quality reference genome of the steppe bison to use as reference to the environmental DNA of steppe bison?

I cannot some in detail on bison, but if the person is interested in the topic searching under the names Beth Shapiro and Duane Froese will turn up useful leads. The specific genome of the steppe bison no longer exists, but there is evidence that it did until very recently (i.e. last 2 centuries) in Alaska and Alberta. From the extinction biology standpoint, this is interesting because it indicates that the so-called Pleistocene extinctions did not end with a bang but a whimper, lasting well into the Holocene. Several species thought to have completely died out at the end of the Pleistocene are now known to have continued on for an uncertain length of time, probably in low numbers. Horse and mammoth are now members of that group along with steppe bison. Something similar may have occurred in South America with horses, but the dating record is much more limited there.

I often hear the argument that if horses survived to more modern times, there would have been bone findings that could be carbon dated to more recent times. What is that answer?

The answer is that there are not any well confirmed macrofossil dates for Holocene survival of horses—yet. Although Holocene survival has been repeatedly alleged in the past, the dates offered up are usually not sufficiently rigorous to be acceptable to most modern workers.

The overarching problem that people usually don’t think about is that very, very few ancient animals were ever preserved well enough or often enough after their deaths to answer questions such as, “when did species X finally die out?” If horse populations collapsed, as they surely did after the Pleistocene/Holocene transition, then at one level it is not surprising that their fossils have not yet been recovered and dated. Radiocarbon dating is expensive, and most Quaternary paleontologists would have to have a good reason to spend scarce research funds on dating a species that they already  ”know” died out 10,000 years ago. Nevertheless, this is a real problem that those supporting late survival have to address.  Cana Foundation is beginning a program in Yukon to ascertain whether Holocene macrofossils can be unequivocally identified ultra -high quality radiocarbon dating. This program is due to start in mid-2022.

Thank you again for joining us.

We look forward to joining CANA and team members for more exciting news in 2022.

image: McMaster Foundation