Genetic Variation in Thomomys bottae Pocket Gophers: Macrogeographic Patterns

Evolution ◽  
1977 ◽  
Vol 31 (4) ◽  
pp. 697 ◽  
Author(s):  
James L. Patton ◽  
Suh Y. Yang
1989 ◽  
Vol 54 (2) ◽  
pp. 370-389 ◽  
Author(s):  
Donald L. Johnson

A prominent subsurface zone (layer) of large stones with diameters greater than 6-7 cm occurs in gravelly soil on colluvial aprons in the Lompoc area of California. The soil is mounded and churned by botta pocket gophers (Thomomys bottae). Sedimentological analyses show that the soil within and above the stone zone—and within the gopher mounds—is relatively homogeneous in fine fraction and forms a biomantle. None of the mounds contained stones with long-axis diameters greater than the maximum diameter of gopher burrows, about 6-7 cm. Larger stones gradually subside and form a stone zone. Both field observations and laboratory tests confirm that gopher bioturbation produces stone zones in coarse gravelly soil. This finding, and similar findings in two other recent studies, have important implications for interpreting archaeological site formation, and for interpreting geologic-pedologic processes inasmuch as artifact layers (and nonartifact layers) in some sites entirely may be due to nonanthropic, nongeologic, postdepositional biological agents.


2004 ◽  
Vol 39 (3) ◽  
pp. 611-625 ◽  
Author(s):  
R. L. Budd ◽  
G. J. Gonzales ◽  
P. R. Fresquez ◽  
E. A. Lopez

2021 ◽  
Author(s):  
Maria Viteri ◽  
Elizabeth Hadly

Understanding the taphonomic biases affecting fossil deposits is necessary in order to extract their true ecological signals. In terrestrial sites, the mixing of fossil material by mammalian bioturbators can substantially increase time-averaging, obscuring or even erasing stratification. In particular, pocket gophers (Thomomys sp.) are known to burrow in Holocene sites and thereby complicate the contextualization of faunal remains. Not only is it unclear if bones have been transported vertically by gophers, but the gophers themselves have the potential to die in their burrows, adding young skeletal remains to older deposits. We establish the degree of bias introduced by gopher remains in a late-Holocene archaeological site in Woodside, California by radiocarbon dating skeletal remains of Thomomys bottae and non-fossorial small mammals from the same stratigraphic units. The ages of T. bottae bones are younger overall, and span a wider range, than the distribution of ages from other small mammals from the same site and sediment layers. This suggests that a significant number of gopher remains have been introduced after the site’s deposition as a consequence of burrowing. These results shed light on a common taphonomic process that affects archaeological and paleontological sites, and may prompt reevaluation of faunal community reconstructions from fossil deposits impacted by gophers and other fossorial mammals.


1976 ◽  
Vol 41 (2) ◽  
pp. 168-173 ◽  
Author(s):  
A. J. Lechner

To examine the adaptations to low O2 and high CO2 among fossorial and nonfossorial rodents, hematological parameters were determined for laboratory rats, the valley pocket gopher (Thomomys bottae) from 250 m, and the mountain pocket gopher (T. umbrinus melanotis) from 3150 m. Hematocrit, hemoglobin concentration, and O2 capacity were higher in pocket gophers than in rats. Blood PO2 at 50% saturation and pH 7.4 was 33 mmHg for both gophers and 39 mmHg for rats. Bohr factors for all three rodents were similar (-0.55 to -0.61) but buffer value, delta log PCO2/delta pH, was -2.54 for T. umbrinus, -1.97 for T. bottae, and -0.98 for Rattus. Concentrations of total acid-soluble phosphates were 50–75% higher in gophers than in rats, while bicarbonate values were within the normal mammalian range. All three rodents had similar myoglobin concentrations in cardiac muscle. Myoglobin concentrations were significantly higher in skeletal muscles (diaphragm, gastrocnemius) of T. umbrinus when compared to T. bottae, and significantly higher in both gophers when compared to rats. These differences may constitute important adaptations to the hypoxia and hypercapnia in burrows; certain of these factors in pocket gophers respond to the additional stress of high altitude hypoxia.


Sign in / Sign up

Export Citation Format

Share Document