Mrj. Forstner et al., GEOGRAPHIC-VARIATION IN WHOLE VENOM PROFILES FROM THE MOTTLED ROCK RATTLESNAKE (CROTALUS-LEPIDUS-LEPIDUS) IN TEXAS, Journal of herpetology, 31(2), 1997, pp. 277-287
Venom variation in the mottled rock rattlesnake (Crotalus lepidus lepi
dus) was assessed by polyacrylamide gel electrophoresis. Whole venom s
amples were stained for general protein, the banding recorded, and the
se profiles were used to compare the variation within and between popu
lations in Texas. Analyses using agglomerative methods (phenetic clust
ering methods and neighbor joining analyses) and ordination from Princ
ipal Components analyses provide several geographically correlated gro
ups of rattlesnake venom profiles. Evidence is provided for difference
s in venom profiles of geographically distinct populations. Venom prof
iles of C. lepidus collected along the Rio Grande River, though geogra
phically disparate, are generally homogeneous. Thus, the analyses supp
ort previously hypothesized dispersal of C. lepidus in Texas along the
se Rio Grande canyons. A potential region of population interchange be
tween eastern plateau populations and those of the west Texas mountain
ranges was identified at the southern end of the Davis Mountains in B
rewster Co. Lethality assessments using LD, analyses reveal variation
in venom toxicity to range from 2.20-0.72 mg/kg across the geographic
range for this subspecies.