scholarly journals The Role of the American Red Squirrel (Tamiasciurus Hudsonicus) in the Evolution of Serotiny in Lodgepole Pine (Pinus Contorta).

2011 ◽  
Vol 33 ◽  
pp. 155-160
Author(s):  
Matt Talluto ◽  
Craig Benkman
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Fire Frequency ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Seed Predator ◽  
Red Squirrels ◽  
Factors Affecting ◽  
And Function ◽  
High Elevations

Coevolutionary interactions can have dramatic effects on the structure and function of ecosystems, particularly when spatial structure leads to local adaptation. Here we report on an ongoing study of the interaction between lodgepole pine and its primary pre-dispersal seed predator, the American red squirrel. Lodgepole pine is serotinous, meaning seeds are held in closed cones until released by the heat of a fire. Serotiny has been shown to increase seedling density following stand replacing fire, and can have far-reaching ecosystem- and community-level implications. Red squirrels are negatively associated with serotiny at broad geographic scales, and may select against the serotinous trait. This project aims to examine the correlation between red squirrel density and the frequency of serotiny in lodgepole pine forests and the mechanisms underlying potential selection against serotiny by red squirrels. Specifically, we will determine whether this correlation is present when other factors affecting serotiny (i.e., fire frequency, elevation) are held constant, whether the fitness of serotinous trees is reduced in the presence of red squirrels, and what factors control the density of red squirrels. Preliminary results indicate that serotiny and squirrel density is strongly negatively correlated, but only at low elevations. Serotiny was nearly absent at high elevations, but squirrel density varied as much as at low elevations, suggesting that serotiny does not control squirrel density, but that increasing squirrel density may lead to increasing selection against serotiny.

scholarly journals A Possible Role for Red Squirrels in Structuring Breeding Bird Communities in Lodgepole Pine Forests

The Condor ◽  
2006 ◽  
Vol 108 (1) ◽  
pp. 232-238 ◽  
Author(s):  
Adam M. Siepielski
Keyword(s):  
Nest Predation ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Bird Communities ◽  
Pine Forests ◽  
Tamiasciurus Hudsonicus ◽  
Breeding Bird ◽  
Bird Abundance ◽  
Red Squirrels ◽  
Cavity Nesters

Abstract Nest predation is thought to play an important role in structuring certain breeding bird communities. One potential consequence of nest predation is lower recruitment in breeding birds, which may be manifested as lower breeding bird abundance. Lodgepole pine (Pinus contorta ssp. latifolia) forests east and west of the Rocky Mountains became isolated following glacial retreat 12 000 years ago and differ in whether or not red squirrels (Tamiasciurus hudsonicus), which are a key nest predator, are present. Breeding bird abundance in lodgepole pine forests was compared between four ranges with red squirrels and four ranges without red squirrels. Species grouped into canopy and understory nesting guilds were, on average, two and three times more abundant, respectively, in forest ranges without red squirrels than in ranges with red squirrels; no statistically significant differences were found for midstory, ground, or cavity nesters. These results suggest that geographic variation in the presence or absence of red squirrels is likely important in structuring breeding bird communities in lodgepole pine forests across the landscape.

scholarly journals The Role of Red Squirrels (Tamiasciurus Hudsonicus) in Shaping Spatial Patterns of Serotiny in Lodgepole Pine (Pinus Contorta) Forests

2011 ◽  
Vol 34 ◽  
pp. 139-145
Author(s):  
Matt Talluto ◽  
Craig Benkman
Keyword(s):  
Seed Predation ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Canopy Cover ◽  
Ecosystem Processes ◽  
Tamiasciurus Hudsonicus ◽  
Individual Species ◽  
Red Squirrels ◽  
Long Term Storage ◽  
Sapling Density

Understanding the effects of individual species on community- and ecosystem-level processes is of critical importance in ecology. Recent work has demonstrated that variation in genetically controlled traits within foundation species can have large implications for ecosystem processes. Identifying these traits and the selective pressures on them is crucial in understanding how ecosystems are structured and how the systems will respond to disturbance. Serotiny, the long-term storage of seeds in the canopy, is thought to be an adaptation to stand replacing fire. Seeds from serotinous plants are released following a fire, and the proportion of serotinous trees determines sapling density following a fire. The effects of serotiny are not limited to the serotinous species, as sapling density is an important determinant of plant community structure and ecosystem processes (including primary productivity and nutrient cycling). Seed predation may select against serotiny, however, no studies have addressed how the relative strengths of selection from fire and seed predation combine to produce the spatial pattern of serotiny on the landscape. Here, we report on an ongoing study of the effects of selection from seed predation in lodgepole pine (Pinus contorta), a serotinous North American conifer. Red squirrels are negatively associated with serotiny at broad geographic scales, and may select against the serotinous trait. This project examined the correlation between red squirrel density and the frequency of serotiny in lodgepole pine forests and the mechanisms underlying potential selection against serotiny by red squirrels. Specifically, we tested whether this correlation was present at landscape scales, whether the fitness of serotinous trees was reduced in the presence of red squirrels, and what factors controlled the density of red squirrels. Preliminary results indicate that serotiny and squirrel density is negatively correlated, but only at low elevations. In the presence of squirrels, we observed significantly lower cone survival in serotinous trees, suggesting reduced fitness. Squirrel density was strongly affected by several measures of forest structure, including species composition, overhead canopy cover, and tree size (mean DBH).

scholarly journals Influence of Fertilization on Feeding Attacks to Lodgepole Pine by Snowshoe Hares and Red Squirrels

1982 ◽  
Vol 58 (6) ◽  
pp. 263-266 ◽  
Author(s):  
Thomas P. Sullivan ◽  
Druscilla S. Sullivan
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Growth And Yield ◽  
Tamiasciurus Hudsonicus ◽  
Average Amount ◽  
Red Squirrels ◽  
Animal Damage ◽  
Snowshoe Hares ◽  
Yield Responses ◽  
And Control

Lodgepole pine (Pinus contorta Dougl.) shows favourable growth and yield responses to spacing (thinning) and potentially to fertilization, but is susceptible to feeding injuries by snowshoe hares (Lepus americanus Erxleben) and red squirrels (Tamiasciurus hudsonicus Erxleben). This study was designed to determine the incidence of animal damage to crop trees in a fertilized-spaced stand, compared with those in spaced only and control (unspaced) stands. There was little variation in the percentage of crop trees (range 53.6% to 63.3%) damaged by hares in the three stands. Hares removed an average of 92.2 cm2 of bark and associated vascular tissues per attack from fertilized stems compared with 46.2 cm2 in the spaced only stand. This latter value was nearly double that recorded in the control stand (27.4 cm2). Squirrels damaged more fertilized trees (38.9%) than trees in the spaced (30.9%) or control (14.3%) stands. Squirrels removed the largest average amount of bark (66.9 cm2) per attack from fertilized stems with little difference between spaced (41.6 cm2) and control (42.3 cm2) stands. We conclude that hares and squirrels clearly prefer to feed on fertilized lodgepole pine stems over those in non-fertilized or un-managed stands.

SEASONAL DAMAGE BY INSECTS AND SQUIRRELS TO FEMALE REPRODUCTIVE STRUCTURES OF BLACK SPRUCE, PICEA MARIANA (MILL.) B.S.P.

1988 ◽  
Vol 120 (12) ◽  
pp. 1113-1121 ◽  
Author(s):  
Y.H. Prévost ◽  
J.E. Laing ◽  
V.F. Haavisto
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Reproductive Structures ◽  
Cone Axis ◽  
Viable Seeds ◽  
Cone Growth

AbstractThe seasonal damage to female reproductive structures (buds, flowers, and cones) of black spruce, Picea mariana (Mill.) B.S.P., was assessed during 1983 and 1984. Nineteen insects (five Orders) and the red squirrel, Tamiasciurus hudsonicus (Erxleben), were found feeding on these reproductive structures. Collectively, these organisms damaged 88.9 and 53.5% of the cones in 1983 and 1984, respectively. In the 2 years, Lepidoptera damaged 61.8% of the cones in 1983 and 44.4% of the cones in 1984. The spruce budworm, Choristoneura fumiferana (Clem.), and the spruce coneworm, Dioryctria reniculelloides Mut. and Mun., were the most important pests. Cones damaged by Lepidoptera could be classed into three categories: (a) severe, yielding no seeds; (b) moderate, yielding 22.3 seeds per cone; and (c) light, yielding 37.5 seeds per cone. Undamaged cones yielded on average 39.9 seeds per cone. Red squirrels removed 18.8% of the cones in 1983 and none in 1984. The spruce cone axis midge, Dasineura rachiphaga Tripp, and the spruce cone maggot, Lasiomma anthracinum (Czerny), caused minor damage in both years. Feeding by spruce cone axis midge did not reduce cone growth significantly or the number of viable seeds per cone, but feeding by the spruce cone maggot did. During both years new damage by insects to the female reproductive structures of the experimental trees was not observed after mid-July. In 1983 damage by red squirrels occurred from early to late September. In 1984 damage to cones on trees treated with dimethoate was 15.6% compared with 53.5% for untreated trees, without an increase in the number of aborted cones.

Genetic structure of the arboreal squirrels (Glaucomys sabrinus and Tamiasciurus hudsonicus) in the North American Black Hills

2012 ◽  
Vol 90 (9) ◽  
pp. 1191-1200 ◽  
Author(s):  
A.M. Kiesow ◽  
E.M. Monroe ◽  
H.B. Britten
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Management Practices ◽  
Allelic Diversity ◽  
Black Hills ◽  
Tamiasciurus Hudsonicus ◽  
Glaucomys Sabrinus ◽  
Red Squirrel ◽  
Isolated Populations ◽  
Red Squirrels

We selected two isolated mammalian populations, the Black Hills northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) and red squirrel ( Tamiasciurus hudsonicus (Erxleben, 1777)), to elucidate their genetic structure. We trapped both squirrels from 2005 to 2007, in three regions of the Black Hills, differing in geology and vegetation, to collect ear samples for genetic analyses. Microsatellite loci (northern flying (9) and red squirrel (13)) were used to examine genetic structure. Data analyses estimated genetic variability, substructure, and gene flow. Northern flying and red squirrel populations have allelic diversity and observed heterozygosity similar to other isolated populations. Each species shows weak substructure from STRUCTURE and GENELAND analyses, suggesting squirrel movements may be inhibited by topography or unsuitable habitat. Recent gene flow estimates from BAYESASS indicate that both species experience some within population gene flow and red squirrels may be more structured than northern flying squirrels because of lower migration rates. Concordant patterns of genetic structure in northern flying and red squirrels indicate that other species’ movements in the Black Hills may be affected by topography and habitat. Because their habitat is isolated in the Black Hills, management practices and conservation measures are recommended to promote viability and survival of each species.

Body temperature dynamics of the red squirrel (Tamiasciurus hudsonicus): adaptations for energy conservation

1979 ◽  
Vol 57 (7) ◽  
pp. 1349-1354 ◽  
Author(s):  
Ronald W. Pauls
Keyword(s):  
Body Temperature ◽  
Motor Activity ◽  
Energy Conservation ◽  
Outdoor Environment ◽  
Tamiasciurus Hudsonicus ◽  
Rapid Decline ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Air Temperatures ◽  
Temperature Dynamics

Abdominal temperatures (Tb) of two captive female red squirrels (Tamiasciurus hudsonicus) in a natural outdoor environment were monitored by radiotelemetry at air temperatures (Ta) from −33 to 28 °C. Abdominal temperature ranged from 35.9 to 41.4 °C with values usually less than 39 °C when an animal was in the nest and greater than 39 °C when outside. An increase of Tb to about 39 °C usually occurred before an animal left the nest. In the nest Tb was positively correlated with Ta. Outside the nest there was a weak positive correlation at Ta less than 15 °C and a stronger negative correlation at higher Ta. During subnivean activity a rapid decline in Tb usually occurred. It is suggested that in the nest a low Tb is adaptive in that it results in energy conservation while a higher Tb is required outside the nest for rapid and coordinated motor activity.

Behavioural strategies relevant to the energy economy of the red squirrel (Tamiasciurus hudsonicus)

1978 ◽  
Vol 56 (7) ◽  
pp. 1519-1525 ◽  
Author(s):  
Ronald W. Pauls
Keyword(s):  
Locomotor Activity ◽  
Air Temperature ◽  
Activity Patterns ◽  
Tamiasciurus Hudsonicus ◽  
Temperature Cycle ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Time Out ◽  
Energy Economy ◽  
Behavioural Strategies

Amount and intensity of locomotor activity and time out of the nest were measured for a 1-year period on captive red squirrels (Tamiasciurus hudsonicus) under natural conditions. Daily and annual activity patterns and correlations between activity and meteorological variables were examined. A pronounced annual cycle, in phase with the annual temperature cycle, was found in all three aspects of activity. Daily amount of locomotor activity and time out of the nest were closely correlated with mean daily air temperature. Wind, photoperiod, and air temperature during the preceding week showed a weak but significant correlation with activity. Daily patterns of activity varied seasonally from a distinctly bimodal to a unimodal pattern, with a shift in winter to more midday activity. The relevance of these behavioural strategies to the energy economy of the red squirrel is discussed.

scholarly journals Mountain Pine Bettle Infestation: Cycling and Succession in Lodgepole Pine Forest

1980 ◽  
Vol 4 ◽  
pp. 119-124
Author(s):  
J. Yavitt ◽  
D. Knight
Keyword(s):  
Pinus Contorta ◽  
Mountain Pine Beetle ◽  
Lodgepole Pine ◽  
Natural Disturbance ◽  
The Past ◽  
Ecological Understanding ◽  
Mountain Pine ◽  
Pine Beetle ◽  
Fuel Accumulation ◽  
And Function

A research project was initiated in the summer of 1980 to study the effect of mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreaks on forests dominated by lodgepole pine (Pinus contorta Dougl. ssp. latifolia) in Yellowstone National Park (YNP), Wyoming. In the past twenty years, beetle outbreaks have become an increasing problem in the Park. These series of infestations first appeared in the Bechler Meadows area in the early 1960's, and have since spread northward with the most recent outbreaks occurring in stands along the Gallatin River. Based on aerial surveys, the highest concentration of beetle activity is currently centered in the West Yellowstone Madison River Canyon area of the Park. Since bark beetle infestations are a natural disturbance or perturbation similar to fire, knowledge of the structure and function of the forest on disturbed patches is vital to the ecological understanding of the landscape. Although the population ecology of mountain pine beetle in pine forests has been well documented (Coulson 1979), little has been done on their effect on ecosystem characteristics. Our approach has been to study 1) various nutrient cycling characteristics, 2) surviving tree growth, 3) succession, and 4) fuel accumulation patterns in a series of stands with different histories of beetle disturbance. The stands were selected to represent a chronosequence of beetle activity, dating from about 1965 to the present.

scholarly journals Seed masting causes fluctuations in optimum litter size and lag load in a seed predator

2018 ◽  
Author(s):  
Andrew McAdam ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
Jeff Lane
Keyword(s):  
Litter Size ◽  
Picea Glauca ◽  
Life Histories ◽  
Local Density ◽  
White Spruce ◽  
Tamiasciurus Hudsonicus ◽  
Seed Predator ◽  
Red Squirrels ◽  
Seed Predators ◽  
Seed Crops

The episodic production of large seed crops by some perennial plants, is referred to as masting and is known to increase seed escape by alternately starving and swamping seed predators. These pulses of resources, however, might also act as an agent of selection on the life histories of seed predators, which could indirectly enhance seed escape by inducing an evolutionary load on seed predator populations. Lag loads in seed predators could result from mast-induced shifts in optimum phenotypes that exceed the capacity of seed predators to adaptively track optimum phenotypes through phenotypic plasticity. Alternatively, masting could generate mismatches in selection across generations, where adaptation to the parental environment leads to maladaptation in the offspring environment. Here we measured natural selection on female North American red squirrels (Tamiasciurus hudsonicus) across 28 years and five white spruce (Picea glauca) masting events. Red squirrel litter sizes were similar to optimum litter sizes during non-mast years, but were well below optimum litter sizes during resource-rich mast years. Mast events, therefore caused selection for larger litters (B = 0.25) and a lag load (L = 0.25) on red squirrels during mast years. Furthermore, we found that the annual fitness of spruce trees was negatively related to the local density of squirrels during mast years, indicating that the observed lag load on squirrels enhanced the number of spruce cones escaping squirrel predation. Although, the frequency of mast events and the demography of red squirrels were such that offspring and parents often experienced opposite environments with respect to the mast, we found no effect of environmental mismatches across generations on either offspring survival or population growth. Instead, squirrels plastically increased litter sizes in anticipation of mast events, which partially, although not completely, reduced the lag load resulting from this change in food availability. Variable selection on litter size caused by white spruce mast events, therefore, induced a lag load on the population of red squirrels that was not affected by whether individual squirrels were born during mast (matching) or non-mast (mismatching) conditions.

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