Experimental crosses between Rana pretiosa pretiosa Baird
and Girard and Rana cascadae Slater, resulted in viable hybrids.
Reciprocal differences at the time of fertilization are indicated. A
high level of success in producing viable hybrids can be obtained if
Rana pretiosa pretiosa is the female of the parent species, The...
Developmental series of Rana pretiosa (110 specimens), R.
cascadae (100 specimens) and R. aurora (115 specimens) were bone
stained and cleared in glycerin. The growth and developmental patterns
of the skull and selected bones were followed from the first
appearance of bone through adult stages. The sequential appearance
of the...
How complex traits evolve continues to be a major focus of evolutionary
investigation. A current topic of debate is the hypothesis that the phenotypic
integration of complex traits gives rise to evolutionary constraints. I studied two color
traits in the common garter snake, Thamnophis sirtalis, that show a high level...
The investigation was conducted from January 1965 to March
1966. An intensive effort was made to obtain large numbers of animals,
as it is believed that unavailability of specimens has been the
limiting factor in the amount of research concerning this species.
Two hundred and sixty-nine animals were collected. They...
In the past decade, declines in amphibian populations have captured scientific and popular interest. The causes of the declines are likely to be complex and involve interactions between several environmental stressors. Using multifactorial experiments, I investigated the combined effects of several anthropogenic stressors on developing amphibians in Oregon, USA. In...