19 research outputs found
Evolution of Morphological Integration. I. Functional Units Channel Stress-Induced Variation in Shrew Mandibles
Stress-induced deviations from normal development are often assumed to be random, yet their accumulation and expression can be influenced by patterns of morphological integration within an organism. We studied within-individual developmental variation ( fluctuating asymmetry) in the mandible of four shrew species raised under normal and extreme environments. Patterns of among-individual variation and fluctuating asymmetry were strongly concordant in traits that were involved in the attachment of the same muscles (i.e., functionally integrated traits), and fluctuating asymmetry was closely integrated among these traits, implying direct developmental interactions among traits involved in the same function. Stress-induced variation was largely confined to the directions delimited by functionally integrated groups of traits in the pattern that was concordant with species divergence-species differed most in the same traits that were most sensitive to stress within each species. These results reveal a strong effect of functional complexes on directing and incorporating stress-induced variation during development and might explain the historical persistence of sets of traits involved in the same function in shrew jaws despite their high sensitivity to environmental variation
Stress and Developmental Stability: Vegetation Removal Causes Increased Fluctuating Asymmetry in Shrews
Environmental stress can increase phenotypic variation in populations by affecting developmental stability of individuals. While such increase in variation results from individual differences in ability to buffer stress, groups of individuals and different traits may have different sensitivity to stressful conditions. For example, the sex that is under stronger directional selection for faster growth may be more sensitive to stressful conditions during development. On an individual level, stress-induced variation in a trait may be related to the strength of stabilizing selection that acts on the trait. We experimentally examined sensitivity of mandibular development to stress in a free-living population of common shrews (Sorex cinereus), a short-lived insectivore mammal with very limited dispersal and nearly continuous foraging activity. We found a strong increase in asymmetry in shrews born under stressful conditions. Increased asymmetry was associated with lower physiological condition in both control and stressed populations, although the effect of asymmetry on fitness was more pronounced under stressful conditions. Males\u27 developmental stability was more sensitive to stressful conditions than developmental stability of females, suggesting that their apparently faster and more variable growth is more sensitive to stress than is growth of females. Mandible traits differed in their sensitivity to environmental changes. Preliminary results suggest that this differential sensitivity is proportional to the degree of developmental and functional morphological integration among mandibular traits
Evolution of Morphological Integration: Developmental Accommodation of Stress-Induced Variation
Extreme environmental change during growth often results in an increase in developmental abnormalities in the morphology of an organism. The evolutionary significance of such stress-induced variation depends on the recurrence of a stressor and on the degree to which developmental errors can be accommodated by an organism\u27s ontogeny without significant loss of function. We subjected populations of four species of soricid shrews to an extreme environment during growth and measured changes in the patterns of integration and accommodation of stress-induced developmental errors in a complex of mandibular traits. Adults that grew under an extreme environment had lower integration of morphological variation among mandibular traits and highly elevated fluctuating asymmetry in these traits, compared to individuals that grew under the control conditions. However, traits differed strongly in the magnitude of response to a stressor - traits within attachments of the same muscle (functionally integrated traits) had lower response and changed their integration less than other traits. Cohesiveness in functionally integrated complexes of traits under stress was maintained by close covariation of their developmental variation. Such developmental accommodation of stress-induced variation might enable the individual\u27s functioning and persistence under extreme environmental conditions and thus provides a link between individual adaptation to stress and the evolution of stress resistance
Human Influences on Elk Movement Rates and Resource Selection in the Wildland-Urban Interface.
Elk (Cervus elaphus) are known to select for refuge from hunting by humans (elk hunting). In many areas in the western U.S., elk hunting is completely excluded in the wildland-urban interface (WUI) as a result of land ownership change and subdivision, thus providing refugia for elk. Many of these WUI elk populations are increasing rapidly, and pose a significant credibility challenge to wildlife managers. The North Hills Elk Herd, in Missoula, Montana, has been growing at ~11 percent since the early 1980s, and the herd now numbers over 300 animals. Landownership is a complex matrix of public and private lands that range from partial to complete exclusion of hunting, thus elk hunting pressure is low and provides multiple refugia. Montana Fish, Wildlife and Parks used elk hunting in this setting to reduce population growth, crop depredation, and habituation. Little is known about the efficacy of elk hunting on elk movement rates and habitat selection. We used First-Passage Time (FPT) and Resource Selection Functions (RSF) analysis based on nine GPS collared adult female elk during three hunting seasons with increasing hunting pressure (2007-2009) to test relationships between elk movement rates and resource selection in the WUI. Elk FPT decreased annually, if they were accessible, and differed by hunting mode and season. Elk selected for intermediate distances from homes, trails, and weakly avoided access. These data have been used to modify hunting season structure, acquire conservation easements, and develop lasting partnerships in a complex matrix of ownerships
Long-Toed Salamanders in Harvested and Intact Douglas-Fir Forests of Western Montana
There is little known about how timber harvest practices have affected terrestrial amphibians in the northern Rocky Mountains. Especially lacking is information on the effects of revised harvest methods that fall within the framework of environmental or New Forestry. We estimated the relative abundance of a common forest amphibian, the long-toed salamander (Ambystoma macrodactylum) captured in pitfall arrays on intact, environmentally harvested, and overstory-removal harvested sites in mixed-conifer forests of western Montana. Pitfall data from 1994 through 1996 showed that previously logged sites contained significantly fewer long-toed salamanders regardless of harvest method used. The number of salamanders captured on intact sites (3.1 salamanders·[array]−1·[100 d]−1) was nearly three times the number captured on logged sites (1.2 salamanders·[array]−1·[100 d]−1). Habitat conditions measured in conjunction with trapping efforts indicated that lower amphibian abundance was associated with decreased numbers of large live trees. Declines in amphibian abundance occurred in the absence of changes in understory vegetation that typically occur when forest canopy is reduced. Our findings suggest that long-toed salamanders responded to changes in the physical environment, probably increased temperatures and decreased moisture. That salamanders should respond so dramatically indicates that immediate changes in physical conditions may profoundly alter habitat quality even when other components of the habitat are unaffected
When Reintroductions are Augmentations: The Genetic Legacy of Fishers (Martes Pennanti) in Montana
Fishers (Martes pennanti) were purportedly extirpated from Montana by 1930 and extant populations are assumed to be descended from translocated fishers. To determine the lineage of fisher populations, we sequenced 2 regions of the mitochondrial DNA genome from 207 tissue samples from British Columbia, Minnesota, Wisconsin, and Montana. In northwestern Montana, fishers share haplotypes with samples from the upper Midwest and British Columbia; in west-central Montana, we detected haplotypes found in British Columbia samples, but also detected a control region and cytochrome-b haplotype not found in source populations. Based on the unique haplotypes found in west-central Montana, we propose that individuals with these haplotypes are descended from a relic population. Fishers in northwestern Montana are likely descended from fishers from the Midwest and British Columbia
Win-Win for Wind and Wildlife: A Vision to Facilitate Sustainable Development
Wind energy offers the potential to reduce carbon emissions while increasing energy independence and bolstering economic development. However, wind energy has a larger land footprint per Gigawatt (GW) than most other forms of energy production, making appropriate siting and mitigation particularly important. Species that require large unfragmented habitats and those known to avoid vertical structures are particularly at risk from wind development. Developing energy on disturbed lands rather than placing new developments within large and intact habitats would reduce cumulative impacts to wildlife. The U.S. Department of Energy estimates that it will take 241 GW of terrestrial based wind development on approximately 5 million hectares to reach 20% electricity production for the U.S. by 2030. We estimate there are ∼7,700 GW of potential wind energy available across the U.S., with ∼3,500 GW on disturbed lands. In addition, a disturbance-focused development strategy would avert the development of ∼2.3 million hectares of undisturbed lands while generating the same amount of energy as development based solely on maximizing wind potential. Wind subsidies targeted at favoring low-impact developments and creating avoidance and mitigation requirements that raise the costs for projects impacting sensitive lands could improve public value for both wind energy and biodiversity conservation
Small mammal use of modified culverts on the Lolo South project of Western Montana - an update
A highway reconstruction project, termed the Lolo South Project, is currently underway in west-central Montana to expand Highway 93 from two lanes to four over a distance of approximately 45 miles from the town of Lolo to that of Hamilton. Portions of this highway bisect a series of wetlands which currently support a variety and abundance of wildlife. As one wildlife mitigation approach, several three- and four-foot-diameter culverts have been placed at these sites to encourage animal movement between the fragmented wetlands. Metal shelves serviced by ramps were installed in three of the culverts to allow animal movement during periods of high water. The current research project continued and expanded upon the initial pilot study which was begun in January 2001 (and reported at the ICOET 2001 meetings). In particular, additional culverts were added to the original study to increase the sample size, and modifications of the shelf design were made based upon early results, and these refinements were rigorously tested. A total of 10 culverts spaced over a distance of approximately six miles along a series of wetlands along Highway 93 are now being studied, five with 25inch-wide shelves (experimentals) and five without (controls). Besides the 3 to 4-foot-diameter culverts originally employed, larger culverts have been added (ranging up to 10-foot-wide squash culverts). An additional four culverts along Interstate 90 through Missoula (ranging from 3- to 10-foot widths) are also being studied. This phase of the study was initiated in October 2001 and will continue through December 2003. Remote sensing TrailMaster® cameras, which are triggered by a combination of heat and motion, were mounted on the roof of each culvert, approximately 15 meters from one entrance. These cameras were positioned so that any mammals traversing the culvert either on the floor of experimental or control culverts or on the ramps in the experimental culverts would be photographed. Cameras are being checked once each week, and film is replaced as needed. Once each month (March - October) the small mammal populations which exist along the wetlands adjacent to the original six culverts are being censussed. For this purpose, 25 Sherman® live traps baited with rolled oats are placed in single transect lines approximately 10 meters from each entrance, with a trap spacing of five meters. Traps are checked twice per day at 6:00 am and 6:00 pm for a total of three days. All animals captured are identified to species, sexed, weighed, their reproductive status noted, aged (immature/juvenile/mature), and marked before being released at the point of capture. Environmental data loggers, which record temperature, light, and humidity levels at 30-second intervals 24 hours/day, were placed at three sites; information from each data logger is downloaded each week. Finally, habitat characteristics adjacent to each culvert entrance are being described. Given this experimental design we are able to determine which small mammal species are present adjacent to the culverts and which of these are actually using the culverts to move between wetland sites on each side of the highway. Seasonal use of the culverts and use of the shelves during periods of high water are being assessed. Activity patterns of those animals traversing the culverts is determined from date and time information imprinted on each photograph. Activity patterns are also being correlated with prevailing environmental conditions. Trapping data to date have identified seven small mammal species living adjacent to the culverts: meadow voles (Microtus pennsylvanicus), deer mice (Peromyscus maniculatus), vagrant shrews (Sorex vagrans) short-tailed weasels (Mustela erminea), House mice (Mus musculus), Columbian ground squirrels (Spermophilus columbianus), and striped skunks (Mephitis mephitis). Other species surely reside here as well, though they are too large for the traps employed. Since the original pilot study the floor of the original shelves has been modified to provide a better surface for small mammals and a “vole tube” has been incorporated to address apparent shyness to enter culverts by meadow voles. Photographic evidence has so far demonstrated culvert use by a total of 23 species including the species listed above (with the exception of the house mouse), and muskrats (Ondatra zibethicus), raccoons (Procyon lotor), coyotes (Canis latrans), red foxes (Vulpes vulpes), and white-tailed deer (Odocoileus virginianus) among others. During periods in which water has covered the floor of the culverts, deer mice, short-tailed weasels, striped skunks, raccoons, and domestic cats have used the shelves in the experimental culverts. Meadow voles, the most abundant small mammal species adjacent to the culverts, have now been observed freely moving through the culverts equipped with tubes. These tubes are also heavily used by weasels. ICOET 2003 Proceedings 343 Making Connections From these data several conclusions can be drawn. Most importantly, several species of small mammals appear to readily use the shelves when water in the culvert would otherwise prevent movement; thus, these devices seem to be very effective. Behavioral differences in some species, notably the meadow vole which will not expose itself to an open environment, have been overcome with the development of a protective tube. Further refinements are continuing to be made. The application of these devices for retrofitting small culverts, as well as their utility in large culverts with permanent water flow were examined. Biographical Sketch: Kerry Foresman received his B.A. degree in zoology from the University of Montana in 1971. He then went on to receive an M.S. degree in zoology from the University of Idaho in 1973. In 1977 he earned his Ph.D in physiology from the University of Idaho. Kerry is currently a professor of biology and wildlife biology in the Division of Biological Sciences at the University of Montana. He is a Mammalian ecologist primarily working on sensitive and threatened species. Much of his research focuses on reintroduction of threatened species. He is also studying the effects of habitat fragmentation on wildlife populations and ways to mitigate such effects
Small mammal use of modified culverts on the Lolo South project of Western Montana
Funding Source: Montana Department of Transportation Total Budget: $24,468. Project Period: January 1, 2001-August 31, 2001 A highway reconstruction project, termed the Lolo South Project, is currently underway in west-central Montana to expand Highway 93 from two lanes to four over a distance of approximately 45 miles from the town of Lolo to that of Hamilton. Portions of this highway bisect a series of wetlands, which currently support a variety and abundance of wildlife. As one wildlife mitigation approach, several three- and four-foot diameter culverts have been placed at these sites to encourage animal movement between the fragmented wetlands. Metal shelves serviced by ramps were installed in three of the culverts to allow animal movement during periods of high water. The current research project was designed to determine the effectiveness of these shelves and to document all species that used them.A total of six culverts spaced over a distance of approximately three miles along a series of wetlands are being studied, three with 25"-wide shelves (experimentals) and three without (controls). The study was initiated in January 2001 and will continue through August 2001. Remote sensing TrailMaster® cameras which are triggered by a combination of heat and motion were mounted on the roof of each culvert approximately 15 meters from one entrance. Two additional cameras were mounted outside the entrance to two culverts. All cameras were positioned so that any mammals traversing the culverts either on the floor of experimental or control culverts or on the ramps in the experimental culverts would be photographed. Cameras are being checked once each week and film is replaced as needed.Once each month a census is made of the small mammal populations that exist along the wetlands adjacent to each culvert. For this purpose, 25 Sherman® live traps baited with rolled oats are placed in single transect lines approximately 10 meters from each entrance, with a trap spacing of five meters. Traps are checked twice per day at 6:00 a.m. and 6:00 p.m. for a total of 3 days. All animals captured are identified to species, sexed, weighed, their reproductive status noted, they are aged (immature/juvenile/mature), and marked before being released at the point of capture. Environmental data loggers which record temperature, light, and humidity levels at 30-second intervals 24 hours per day were placed at three sites; information from each data logger is downloaded each week. Finally, habitat characteristics adjacent to each culvert entrance are being described. Given this experimental design we are able to determine which small mammal species are present adjacent to the culverts and which of these are actually using the culverts to move between wetland sites on each side of the highway. Seasonal use of the culverts and use of the shelves during periods of high water are being assessed. Activity patterns of those animals traversing the culverts are determined from date and time information imprinted on each photograph. Activity patterns are also being correlated with prevailing environmental conditions.Trapping data to date has identified four small mammal species living adjacent to the culverts: meadow voles (Microtus pennsylvanicus), deer mice (Peromyscus maniculatus), vagrant shrews (Sorex vagrans) and shorttailed weasels (Mustela erminea). Additional species too large to enter these traps have been documented by photographs and include striped skunks (Mephitis mephitis), muskrats (Ondatra zibethicus), raccoons (Procyon lotor), coyotes (Canis latrans), domestic cats (Felis domesticus), and domestic dogs (Canis familiaris). Photographic evidence has so far demonstrated culvert use by deer mice, skunks, short-tailed weasels, muskrats, raccoons, and domestic cats. No evidence of culvert use has been observed for coyotes, domestic dogs, or meadow voles.ICOET 2001 Proceedings 582 A Time for Action During periods in which water has covered the floor of the culverts the smaller species (deer mice, short-tailed weasels, and domestic cats) used the shelves in the experimental culverts. Raccoons were observed to walk through the water even when a foot deep. Interestingly, the smallest species (weasels and mice) always walked along the solid frame at the edge of the shelf rather than using the open, diamond-shaped, grated surface. Ninety-eight percent of the photographs documenting animal use during the months of January through April (n = 246) were recorded during periods of darkness. Trapping data indicate that vole populations were highest along wetland areas where dense ground vegetation was present. Deer mouse populations were highest in more open areas.From this preliminary data several tentative conclusions can be drawn. Most importantly, several species of small mammal appear to readily use the shelves when water in the culvert would otherwise prevent movement thus these devices seem to be very effective. However, nearly all photographs of smaller species using these shelves clearly shows movement along the solid frame which supports the edge of the flooring rather than movement over the floor surface. This suggests that it is difficult for these species to walk over the large, 1" diamond-shaped openings of the grate surface.One species, the meadow vole, though abundant within a few meters of most culvert entrances, has yet to be documented in any culvert (on the floors during dry periods or on shelves during wet periods) suggesting that this species may view the culverts as a barrier. This is not surprising, as this species is known to prefer an environment where protective cover is available. Meadow voles rarely venture into an open area such as short grass vegetation or a road surface. Species’ presence near culvert entrances clearly appears to be affected by vegetative characteristics at these sites. Deer mice are more abundant where the vegetation is low and more open while voles are abundant where vegetation is denser.Continued work through wet periods in the spring and early summer will provide further data to address the questions posed. Additional modifications of the existing shelves are being considered to test the observation that the shelf surface is too open to provide adequate support for the smaller species. In addition, modifications are also being considered that would address the unwillingness of voles to enter the culverts. Possibly some form of enclosure which runs through the culverts and extends in to the vegetation would provide the needed protection for this species to successfully traverse the highway. Currently populations of this species on opposite sides of the highway appear to be entirely isolated. A grant proposal has been submitted to expand upon this study in order to increase the sample size of culverts, and to test modifications of the shelf structures and the concerns with vegetative cover at and adjacent to the culvert entrances