Rocky Mountain Population Research Articles

A Test for Isolation-by-Distance in Central Rocky Mountain and Great Basin Populations of Edith's Checkerspot Butterfly (Euphydryas editha)

A Test for Isolation-by-Distance in Central Rocky Mountain and Great Basin Populations of Edith's Checkerspot Butterfly (Euphydryas editha)

Recruitment in Rocky Mountain Greater Sandhill Cranes and Comparison with Other Crane Populations

The sandhill crane (Grus canadensis) has the lowest known recruitment (% juv in fall and winter of any avian species hunted in North America. Long-term recruitment data provide insight into a population's productivity, ability to support harvest, and responses to management programs. During 1972-92, we annually collected age ratio (n = 191,968) and brood size (n = 12,239) data for greater sandhill cranes (G. c. tabida [greaters]) of the Rocky Mountain Population (RMP) at their migration stopover in the San Luis Valley, Colorado (fall), and at sites in New Mexico (winter) and southeastern Arizona (winter). We collected similar data (1987-92) for lesser sandhill cranes (G. c. canadensis [lessers]) from the Midcontinent Population (MCP) wintering in flocks mixed with RMP cranes, and for greaters of the Lower Colorado River Valley Population (LCRVP) wintering in western Arizona (1973-75 and 1989-92). Annual recruitment in the RMP averaged 8.1% (SE = 0.6) in fall and 8.0% (SE = 0.5) in winter over 21 years; mean brood size was 1.25 (SE = 0.02) in fall and 1.23 (SE = 0.02) in winter. In years with higher percent juveniles, more pairs fledged multiple young (P < 0.01); second and rarely third chicks in broods composed 20% of RMP recruitment. Recruitment and brood size had a downward trend (P < 0.01) over 21 years. During 1986-92, recruitment and brood size were below average (P < 0.01), apparently due to drought in breeding areas. We estimated survival rates of RMP cranes to be 0.95 during 1972-85, 0.94 during 1985-90, and 0.91 during 1990-92. Recruitment, survival estimates, and count data during 1985-92 suggest that the RMP is stable at 20,000-21,500 or declining slightly and cannot sustain increased harvest. Recruitment in MCP lessers averaged 11.2% (SE = 0.34) and mean brood size was 1.14 (SE = 0.02). Mean recruitment in LCRVP greaters was 4.8% (SE = 0.93), and mean brood size was 1.14 (SE = 0.028). Mean recruitment in most other North American crane populations was 5-14%. The whooping crane (G. americana) has the highest long-term (55 yr) recruitment (13.9%) of any North American crane population. Recruitment data alone cannot be used to estimate rate of increase and are difficult to interpret without additional demographic information. However, perennially low recruitment (≤ 5-6%) approximates the lowest documented mortality rates in any North American crane population, and should be a cause for concern, particularly in hunted populations. Management of crane populations can be improved by annually gathering data on recruitment, population size, and hunter harvest, and by obtaining survival estimates from long-term studies

Trumpeter Swans Relearn Migration

F or 57 winters, swan conservation success at Red Rock Lakes National Wildlife Refuge in Montana has been measured by the increased numbers of trumpeter swans seeking handouts of winter wheat at the crowded man-made ponds. sign of success this year will be frozen ponds, no handouts, and no swans. Half a century of coddling has been so successful that the Rocky Mountain population of trumpeter swans (Cygnus buccinator) has grown from fewer than 200 individuals in 1935 when the refuge was founded to 2200 today. Because of behavioral peculiarities associated with migration, numbers are now the greatest liability of these snowy aristocrats with French horn voices. Approximately 1700 of the birds migrate to western Canada in summer to nest, but almost all return to the high Yellowstone country around the refuge to winter. other 500 swans have given up migrating entirely; they nest and winter in this harsh region where Montana, Idaho, and Wyoming meet. Unlike other birds, these swans seem to lack both the temperament and the knowledge to disperse voluntarily to better and less-crowded winter quarters. During winter, we have all our eggs in one basket, says Ruth Shea, a swan expert with the US Fish and Wildlife Service (USFWS). The swans are very vulnerable. A blizzard or disease could wipe out a large proportion of the population. Three years ago, the agencies and biologists involved in the Pacific Flyway Council shifted tactics in their half-century effort to pull the Rocky

Fluctuation in a Rocky Mountain Population of Salamanders: Anthropogenic Acidification or Natural Variation?

We monitored the demographics of the salamander Ambystoma tigrinum nebulosum as part of a community-wide study on the effects of acidification in sub-alpine (elevation 3600 m) ponds in central Colorado. A decline in A. t. nebulosum at this site from 1982 to 1988 has been hypothesized to result from embryonic mortality during a pulse of acidity that accompanies snowmelt in spring. Since 1988 we have monitored salamander population size, reproduction, and recruitment, and compared survival and individual growth rates among ponds which differ five-fold in acid-neutralizing capacity (ANC)

Geographic monoterpene variability of Pinus albicaulis

Wood of 24 populations of P. albicaulis (243 trees) sampled throughout its geographic range was analysed for monoterpenes. Californian populations were separated from the rest on the basis of higher 3-carene levels, while Rocky Mountain populations were segregated from the northwestern populations on the basis of higher limonene levels. Populations from southern Oregon were intermediate between the California and northwestern populations. Diversification of the eastern and western populations is explained by the effect of low, more arid regions during the Tertiary and Quaternary; that of the California populations is most likely due to the loss of genes during interglacial range contractions. The diversification found militates against evolution of the species from a recently arrived P. albicaulis ancestor from Asia.

Nonhunting Mortality in Sandhill Cranes

Records of 170 sandhill cranes (Grus canadensis) necropsied at the National Wildlife Health Research Center, Wisconsin, from 1976 through 1985 were reviewed as representative samples to determine causes of nonhunting mortality in the mid-continent and Rocky Mountain populations of sandhill cranes. Avian cholera, avian botulism, and ingestion of mycotoxins were leading causes of nonhunting mortality. Hailstorms, lightning, lead poisoning, predation, avian tuberculosis, and collisions with power lines also killed

Field Observations of Courtship Behavior in Rocky Mountain Populations of Van Dyke's Salamander, Plethodon vandykei, with a Description of Its Spermatophore

Field Observations of Courtship Behavior in Rocky Mountain Populations of Van Dyke's Salamander, Plethodon vandykei, with a Description of Its Spermatophore

Quantitative variation of grindelane diterpene acids in 20 species of North American Grindelia

The distribution and quantitative significance of 14 resin acids from 20 species of Grindelia (Asteraceae) in 50 populations from the western U.S. have been determined. Variations in resin acid composition were found between species and between populations within species. Two distinct patterns of resins were obtained, one with grindelic acid as the main component and another with 17-acetoxygrindelic acid. Rocky Mountain populations showed greater variability in resin acid composition than those of the Pacific Coast states.

Geographic Size and Non-Size Variation in Rocky Mountain Tamiasciurus hudsonicus: Significance in Relation to Allen's Rule and Vicariant Biogeography

Multivariate analysis of cranial characters of Rocky Mountain populations of the red squirrel, Tamiasciurus hudsonicus , was employed in an evaluation of geographic variation. Principal components analysis yielded a relatively weak size component which was not significantly correlated with environmental variables. Homogeneous morphology of conifer cones in this area may not provide the strong pressure for size variation suggested in a similar analysis of T. douglasii . A relatively strong non-size component was not significantly correlated with indices of conifer cone morphology, was moderately correlated with temperature, and was highly correlated with latitude and humidity. Correlation of latitude with weather variables indicated the lack of an environment favorable for size variation according to Bergmann's ecogeographic rule but highly favorable to proportional variation according to Allen's rule. The vicariant biogeography of the Southwest is proposed as a means of enhancing the selective capabilities expected under Allen's rule. From this analysis it appears that, with the lack of strong biotic selective forces in the area, squirrels are being more heavily affected by abiotic pressures.

Biosystematics of Sisyrinchium Section Bermudiana (Iridaceae) of the Rocky Mountains

Prior to this study thirteen taxa ofSisyrinchium sectionBermudiana were recognized as occurring in the Rocky Mountains. Morphological intrapopulational variation and hybridization with polyploidy has led to a general lack of discrete phenetic discontinuities among the species, resulting in differing taxonomic treatments. A biosystematic study utilizing morphology, cytology, analysis of breeding systems, and hybridization was undertaken to resolve the taxonomy of Rocky Mountain populations ofSisyrinchium. The following taxa are considered to be valid species of the Rocky Mountains:S. septentrionale Bicknell, a tetraploid (n=16), the octoploids (n=32)S. idahoense Bicknell andS. radicatum Bicknell, and the duodecaploid (n=48).S. montanum Greene. In addition, a previously undescribed, octoploid species,S. pallidum (with close affinities toS. idahoense) was discovered in north-central Colorado and southeastern Wyoming.

Drosophila pseudoobscura of the Great Basin II. Third Chromosome Arrangements of Selected Northern Utah Populations

Populations of Drosophila pseudoobscura from the Wasatch and Uinta Mountains in Utah were sampled and characterized for third chromosome gene arrangements. The original samples in this geographic area were taken in 1940 and 1950. At that time the populations were essentially monomorphic for the Arrowhead arrangement, with small percentages of Pikes Peak and Chiricahua also found. The current samples show these populations to contain nine third chromosome arrangements: eight previously described (AR, PP, CH, ST, TL, OL, EP, FC) and a newly discovered endemic arrangement (American Fork, AF). The frequency of Arrowhead has decreased to 25% in certain areas, the highest frequency found being 63%. This observed array of arrangements is very similar to the Rocky Mountain populations of Colorado. Those populations are the only ones which could contribute all the "new" arrangements observed in this study. Passive wind-aided transport of flies seems unlikely to be responsible for the changes seen, and other forms of active and passive dispersal are considered. Due to the diversity and extent of the changes observed it is improbable that any one mechanism or event could account for these changes.

Chemosystematic studies in the genus Pseudotsuga. IV. Inheritance and geographical variation in the leaf oil terpenes of Douglas-fir from the Pacific Northwest

Quantitative terpene analysis of the leaf oils of 433 wild Douglas-fir trees from 87 northwestern localities, 66 wind-pollinated progenies of 4 trees from Idaho, 100 trees from 5 localities represented in a provenance trial, and 76 trees from four full-sib families of F1 intervarietal crosses allowed assessment of biosynthetic pathways, geographic variation, and modes of inheritance. Hypothetical biosynthetic pathways, derived from the cooccurrence of terpenes implied that the variation in 17 monoterpenes could be represented by three or four biogenetic pathways. As a result, geographic variation between the coastal and Rocky Mountain varieties can be described by the relative percentages of β-pinene, the terpinene–sabinene group of terpenes, the camphene group, and perhaps limonene. An abrupt reduction in the production of the camphene group occurs in going from interior to coastal populations. Moreover, patterns of segregation within four full-sib intervarietal hybrid families suggested that production of high relative percentages of the camphene group was governed by a single dominant gene. The dominant allele is characteristic of the Rocky Mountain variety, but isolated occurrences were also found on dry sites in coastal British Columbia. The recessive allele occurs far into the range of the Rocky Mountain variety. The coastal variety is characterized by the synthesis of relatively large amounts of β-pinene and the terpinene–sabinene group and their mode of inheritance is quantitative. Although concentrations of these terpenes decline towards the Rocky Mountains, genes controlling high amounts occur in populations of Idaho and western Montana. The variation in β-pinene and terpenes of the terpinene–sabinene group does not appear to be clinal. Trees with 5–10% ocimene are predominant in eastern Oregon. This terpene was found only in less than 1% amounts in trees from the coastal region and Montana and was practically absent in a provenance from Arizona. Hence it may serve to differentiate Rocky Mountain populations.

CHEMOSYSTEMATIC STUDIES IN THE GENUS ABIES. IV. INTROGRESSION IN ABIES LASIOCARPA AND ABIES BIFOLIA

SummaryThe volatile oils of the leaves of alpine fir were analyzed by gas‐liquid chromatography. In the Pacific Northwest, alpine fir separates into two types, Coastal and Rocky Mountain. They were distinguished by quantitative differences in santene, tricyclene, camphene, β‐pinene, myrcene, β‐phellandrene, borneol, and ∗∗∗bornyl acetate. Coastal populations had red colors in the periderm, whereas the Rocky Mountain populations had only brown colors. A literature search revealed additional differences between these populations which were originally described as Abies lasiocarpa (Hook.) Nutt. and A. bifolia Murray, respectively, and more recently as only A. lasiocarpa or as a single variety of A. balsamea. However, our evidence suggests that the original designations more accurately describe these two populations, which have hybridized extensively.

Genetic Compatibility in Wood Frogs (Amphibia, Anura, Ranidae)

Wood frogs have been found in five areas of northern Colorado and southern Wyoming. In 1969, Porter designated these populations as Rana maslini, a new species, on the basis of reputed genetic incompatibility with Rana sylvatica from Manitoba. In the present study 154 experimental matings were performed between Wood Frogs from the Rocky Mountain population and from Manitoba. The hybrids showed no loss of genetic compatibility. Numerous offspring were hatched and reared through metamorphosis. On the basis of these results, it is suggested that the name Rana maslini for the Rocky Mountain Wood Frog is invalid.

Phenology and Growth of Rocky Mountain Populations of Deschampsia Caespitosa at Three Elevations in Colorado

Populations of Deschampsia caepitosa (L.) Beauv., collected from 20 sites in Colorado, northwestern Wyoming and western Montana, were studied for patterns of ecotypic differentiation. Three uniform gardens in northcentral Colorado, at elevations of 1,580, 2,740 and 3,570 meters, were utilized to represent the range of environments for the populations. The populations were consistently different from each other in stature and rates of phenological development at all gardens. The patterns of response could be closely related to elevational gradients and differences in the length of the growing season of the native sites. Populations from high elevation sites with short growing seasons were earliest in development, had shorter periods of growth, and were shorter in height than those from low elevations. Survival of all populations was high in all three gardens after the effects of disease in the lowest garden were accounted for.

EVOLUTIONARY STATUS OF THE ROCKY MOUNTAIN POPULATION OF WOOD FROGS.

The Wood frog, Rana sylvatica Le Conte, has an extensive distribution which ranges from Alaska south and eastward through much of Canada and the northeastern United States; a population assigned to R. s. cantabrigensis by Maslin (1947) occurs in the mountains of northcentral Colorado and southeastern Wyoming. Martof and Humphries (1959) studied the geographical variation in morphology of this species and concluded that no subspecific taxon was warranted. These workers noted, however, that the Mountain type, represented in their study by 12 specimens from southeastern Wyoming, 16 from northcentral Colorado, and two questionable ones from Yellowstone County, Montana, was most obviously different from the others. They assumed that Rana sylvatica is also distributed in the intervening areas of the Bitterroots and Rockies and, on their various maps, the Mountain type extends from Montana to northern Colorado and is continuous with the populations in Canada. No locality data were given to support such a distribution, nor are any specimens known from the area between the Medicine Bow Mountains in southeastern Wyoming to the northern tip of Idaho (see Figure 1 for known localities in Colorado and Wyoming). On the basis of habitat distribution alone, the Rocky Mountain population is certainly relict and isolated by a considerable distance from its kind in the north. This southern disjunct population undoubtedly reflects a southward displacement in the Wisconsin and subsequent return northward of these cold-adapted frogs after the close of the Wisconsin. Given sufficient time, speciation as a result of geographical isolation seems inevitable, but scanty data are ava.ilable bearing on ages of species or rates of divergence of sister populations. In a previous study of the Dakota Toad (Porter, 1968), I found that a measureable amount of divergence has occurred between the relict population in Wyoming and its kind in the Dakotas and Manitoba, but breeding experiments indicated the genetic divergence has not been sufficient to affect fertility rates or viability of progeny from interpopulational crosses. Presumably, the southern relict populations of Dakota Toads and Wood Frogs have been separated from their parental populations for about the same length of time. Thus, the purpose of the present study was to use both morphological and nonmorphological approaches to compare the Colorado-Wyoming Wood frogs with those in southern Canada, to determine the stage of speciation of this relict population, and to compare the results with those from the toad study.

Evolutionary Status of the Rocky Mountain Population of Wood Frogs

Evolutionary Status of the Rocky Mountain Population of Wood Frogs