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CKing
at Tue Nov 25 21:06:49 2008 [ Report Abuse ] [ Email Message ] [ Show All Posts by CKing ]
>>All other known populations that occur between the San Bernardino Mts. and Kern Plateau have been tested and align with the Northern Clade (Sierra Nevada subclade)>>
That actually depends on how the Sierra Nevada subclade is defined. All those populations in the Sierra Nevada, north of Tulare County, are of the large morph variety, according to your data. The Kern County animals are all small morph. If you look at the tree in Fig. 3A of Rodriguez-Robles et al., you can see that sample #26, from Tulare County, is actually basal to (older than) a large group of populations which occur both north and south of Tulare County. Together with the new finding of umbratica in Tulare, it would appear to me then that the current Kern County animals are descended from a Tulare County population (#26). That suggests to me that the distributional gap between umbratica and the Kern County small morph animals was even larger in the past than it is today. Therefore the Scodie Mountain population may well have migrated to its current position from Tulare County, rather than being a bridge population between San Bernardino and Kern County populations.
>>Those populations include boas that occur in the Piute Mts. about 12 miles west of the Scodie Mts. and again separated by the Mojave Desert. Only one sample from the Piute Mts. was tested by Rodriguez-Robles and repeated in the current study. I have another sample of tissue from a boa from the Piutes that wasn't tested. And just west of the Piute Mts. is Breckenridge Mt. and south of the Piutes are the Tehachapi Mts. The boas from Mt. Pinos boas to the southwest of the Tehachapi Mts. on the west side of the I-5 corridor and Frazier Park, Calif. were also tested. I have additional samples from all of those regions.>>
Here is my prediction: all of these boas found between Tulare and San Bernardino Mountains are closer to the Sierra Nevada subclade than they are to umbratica. That means they migrated south from Tulare County rather than north from San Bernardino County.
>>As for the 38 samples that had identical haplotypes, that certainly is of interest which from my limited understanding of mtDNA research would seem to suggesting a rapid dispersal by a successful general phenotype.>> >>Richard F. Hoyer
Agreed. These populations are all large morph, suggesting that the evolution of the larger morph has enabled it to radiate into new habitats. The small morph southern rubber boas are probably restricted in distribution to a few mountain refugia by its closest relative, the Rosy boa.
In case you haven't read some of my posts concerning rosy boa mtDNA, this newly published data on the Rosy boa suggests that it originated in northern Baja California. That means the rosy boa probably descended from an isolated population of the rubber boa in the vicinity of northern Baja, while all of the intermediate rubber boa populations in the lower elevations of southern California must have been extirpated, ostensibly by a drying of the climate, which also wiped clean of these mountains of the basal populations of L. zonata. L. z. pulchra and L. z. parvirubra are both recently derived from L. z. agalma according to mtDNA data, just as all other populations of Lichanura are derived from a northern Baja California population. There is amazing agreement between the mtDNA data of L. zonata and Charina/Lichanura, especially in what these data sets are informing us of past evolutionary events and likely geologic history. Fascinating stuff.
It looks like the Rosy Boa and the Northwestern subclade of the Rubber Boa may have converged on the same solution: a larger body size to cope with hotter and drier climates. The same solution has enabled both of these descendant lineages of the small morph rubber boa to exploit new habitats and expand their ranges.
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