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RE: C. bottae taxonomy - A new wrinkle

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Posted by: RichardFHoyer at Sun May 18 22:14:09 2008  [ Report Abuse ] [ Email Message ] [ Show All Posts by RichardFHoyer ]  
   

CK,
If the zonata study to which you refer was by Javier, then though Rob Lovich, I contributed some tissue to that study from the zonata population in the San Bernardino Mts.

As of the present time, I have contributed about half of the samples for the current C. bottae mtDNA study. I still am in possession of over 600 tissue samples that I hope one day someone can be of use, particularly for an in-depth nuclear DNA study. The recent new results I find particularly rewarding as those samples were not part of the initial study and only at my urging did the individual agree to have them tested. I asked about the Mt. Lassen situation but he has yet to examine those results.

However, from the table that lists the localities of tested samples in this new study, 13 new samples originate from the general region close to samples #6 (Eagle Lake) and #15 (Greenhorn Creek east of Quincy) in Javier's study. However, in checking the localities on my de Lorme atlas software map, only 6 of are located what might be considered as in-between 6 and 15. So I am not all that hopeful that new information will emerge to clarify the issue.

Instead of some type of barrier or break occurring in the distribution of the species in that region, those 13 new samples add support to the scenario of a continuous distribution. Even if there had never been a single boa documented in that region, the biological evidence of unbroken suitable habitat clearly indicates an unbroken distribution of the species particularly in this instance where there is zero evidence of any existing barrier or break in boa distribution in the region. As mentioned, simply by having two voucher specimens having been found 60 or 120 km apart is not evidence of a discontinuous distribution. And that is why I was perplexed that Javier would state that the two subclades are separated by some imagined break that occurs somewhere in the vicinity of Lassen Volcanic National Park.

You mention having to disprove his Theory. Theories are established on a preponderance solid evidence and not on pure speculation. Since no evidence exists for the imagined break in distribution, there is nothing to disprove. On the contrary, it should be up to researchers to present solid evidence for the existence of a barrier or a break in distribution.

As for sample #26 from the southern Sierras (Tulare County) that was aligned with 4 specimens from the northern Sierras, that in itself seems a bit odd. Since Fig. 1B showed
those 5 specimens to be somewhat disjunct from the Sierra Nevada subclade, I looked up their collection data. I found there is an error for #26 in that the coordinates are for the center of the city of Tulare. Yesterday I informed the researcher of that error. The specimen is from the Cal Poly collection and hopefully Glenn Stewart will be able to find the correct locality information.

Either I have failed to adequately communicate the biological realities regarding the two subclades in the Mt. Lassen area or perhaps my understanding of the term 'allopatric' is somehow different from common usage or understanding. It has been my understanding that allopatry is where populations are isolated from one another and never meet. It they meet somewhere but essentially remain separate, the term parapatric would come into play. Where two populations meet and where there occurs some overlap in distribution, I have considered that to be a case of sympatry

I will concede that the subclades could basically be parapatric and that any overlap of mtDNA types could be minimal due to some reproductive / behavior incompatibility or selection against hybrids. But without evidence of any existing barrier, the odds are essentially 100% that the two subclades meet and thus overlap even if only to a small degree. Now if my understanding of the terms 'allopatric' , 'parapatric' and 'sympatric' are incorrect, then at least you can understand where I have gone astray.

In some respects, interpretations of results boils down to the 'art' or creativity that is inherent in scientific endeavors. I have wondered how others would have written the manuscript on C. bottae taxonomy given the same data and mtDNA results. Understanding the species as (I think) I do, I would not have even hinted that a break in distribution occurs in the Mt. Lassen area based on the results that show the two subclades as having separate distributions. And theorizing what some type of past or present barrier accounts for the
complete separation of the two subclades is the type of speculation I believe to be unwarranted. The problem with such speculation is that subsequently, others cite such claims
as if established fact. As examples, such speculation about the Sharp-tailed Snake only eating slugs and the blunt tail of the boa being a defense against predators are two cases where conjecture essentially became established fact in subsequent references of those species.

That Javier has a creative imagination was also revealed in a previous study he did on the diet in the Rubber Boa. Based on the results he obtained, he made the claim that a shift in diet occurs in the species whereby small members of the species only consume lizards and their eggs. Larger specimens of the species then includes small mammals and birds and ceases to eat lizard eggs.

What he did not understand (and again, this is where the review process failed) is that the boa occurs in regions that lack any egg laying lizards. The N. Alligator Lizard, a live bearer, occurs sympatric in a reasonably large area of the boas in Oregon, Washington, and B.C. I have recorded umpteen cases in which juvenile and small subadult boas have consumed nestling small mammals just as do the adults. I believe this particular case is where Javier placed to much faith in results extracted from a relatively small sample without adequate geographical representation. And I contend that situation was another clear example where the review process failed--miserably I might add!

As for allopatry, a similar situation occurs with respect to the large and dwarf morphs. If my understanding of the term 'allopatry' is correct as indicating complete separation,
then up to early 2002, based on the information at hand, I considered it very likely that the two morphs had allopatric distributions with the dwarf form occurring only on the isolated mountain peaks and ranges south of the main Sierra Nevada Mts.

At the time I completed my study of the SRB in the San Bernardino Mts. and discovered that population was indeed a dwarf form of the species, starting in 1997 I began working my way north and west to determine if other populations of the species were also dwarf. By 2001, I determined that the Tehachapi Mt. population was dwarf and had fragmentary data suggesting the same situation for boas on Mt. Pinos and on Breckenridge Mt.

In 2001, with my binocs I scanned the Scodie Mts. due east of Lake Isabella. With what appeared to be coniferous trees at the upper elevations, I entertained the notion that the species might exist in that small isolated mt. range despite being surrounded by Mojave Desert. Maps indicated an elevation of 6000 ft. The boa had already been document on the Piutes due east of Breckenridge but not the Scodie Mts. At the time, I mentioned to Brad Alexander of Kernville that we should make searches there in 2002.

In April of 2002, I could not get down the weekend Brad chose to go to the Scodie Mts. Along with Robert Hansen and others, Brad found a single female boa (under a lone piece of
roofing tin) in the Scodie Mts. which by all indications was an adult of the dwarf morph. As a matter of fact, that boa produced a litter which pretty much clinched that issue. Then in late April of 2002, as the two of us were driving up to the S. Kern Plateau to conduct searches (Brad for zonata and myself for Charina), I asked if he thought the dwarf morph occurred on the Kern Plateau. I expected him to reach the same conclusion as myself but instead he indicated he felt the dwarf morph would occur there as well. And as it has turned out (and to my surprise), he was right. So much for my 'theory' of allopatric distributions of the two size morphs.

Discovering the dwarf form on the S. Kern Plateau and in the southern Greenhorn Mts. changed by view 180 degrees. Yes, still allopatric in their broad scale distribution but certain no longer allopatric on a finer scale as there simply has to be zones in the Greenhorn Mts. and on the Kern Plateau where the two morphs came in contact. Constructing an imaginary geographical barrier that would keep the two morph separated would be just as implausible as theorizing imaginary geographical barriers in the Mt. Lassen region.

Richard F. Hoyer


   

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