Future correlational studies must explicitly consider phylogeny and should also be supplemented by detailed studies of particular transitions to dioecy - studies of the sort that have clarified analogous issues such as heterostyly.

Experiments were conducted to compare the patterns, mechanisms, and costs of predator avoidance behavior among larvae of five species of mayflies that co—occur with the predatory stoneflies, Megarcys signata and Kogotus modestus in western Colorado streams. Mayfly drift dispersal behavior, use of hi

The interactions between floral resource phenology, bee foraging behaviour, and traits such as diet breadth, sociality, and body size are discussed and greater use of information contained in museum collections on bee phenologies and floral hosts is encouraged.

Atmospheric nitrogen (N) deposition to lakes and watersheds has been increasing steadily due to various anthropogenic activities. Because such anthropogenic N is widely distributed, even lakes relatively removed from direct human disturbance are potentially impacted. However, the effects of increase

I examined the response of bumblebees to two kinds of spatial variation and two kinds of temporal variation in nectar levels. The spatial variation involved differences in reward value among plant species and differences in nectar availability among patches of flowers of a single species. The tempor

Pathogens and herbivores can severely reduce host fitness, potentially leading to altered succession rates and changes in plant community composition. Thus, to predict vegetation dynamics under climate change, it is necessary to understand how plant pathogens and herbivores will respond. Pathogens a

Carol L. Boggs1,2* and David W. Weather drives population dynamics directly, through effects on vital rates, or indirectly, through effects on the Inouye1,3 populationÕs competitors, predators or prey and thence on vital rates. Indirect effects may include non-additive 1 Rocky Mountain Biological in

AbstractSurveys of bumble bees and the plants they visit, carried out in 1974 near the Rocky Mountain Biological Laboratory in Colorado, were repeated in 2007, thus permitting the testing of hypotheses arising from observed climate change over the intervening 33‐yr period. As expected, given an incr

This study describes nectar production patterns for Ipomopsis aggregata and discusses their potential adaptive and ecological significance. It also examines the influence of environmental and other factors on nectar production rate (NPR) and nectar sugar concentration. For I. aggregata there were no

Consequences of species-area relationships (SARs) of the form S = cA are derived. One consequence is an endemics-area relationship (EAR); it is of the same power-law form as the SAR but with an exponent z' that is a function only of z and that always exceeds unity. An explicit formula is derived for

There is no evidence that flight characteristics depend on anything as straightforward as whether flower visitors have high or low energetic requirements, and all the visitors to a given plant species fly similar, short distances between successively visited flowers and plants.

-Flower-visiting Diptera are abundant in montane and Arctic areas. This research, conducted on the western slope of the Colorado Rocky Mountains: (1) characterizes the predominant anthophilous fly taxa in comparison with other high-elevation and highlatitude sites; (2) examines changes in fly abunda

Alpine environments are among the habitats most strongly affected by climate change, and consequently their unique plants and pollinators are faced with the challenge of adapting or going extinct. Changes in temperature and precipitation affect snowpack and snowmelt, resulting in changes in the grow

AbstractVarious aspects of the pollination biology of the alpine flora of Kosciusko National Park, NSW, were examined from late December 1983 until the end of March 1984, including flowering phenology, corolla tube lengths, flower colour, ultraviolet reflectance patterns, visitation rates to the flo

1. Shifts in the spatial and temporal patterns of flowering could affect the resources available to pollinators, and such shifts might become more common as climate change progresses. 2. As mid-summer temperatures have warmed, we found that a montane meadow ecosystem in the southern Rocky Mountains

In the central Rocky Mountains of Colorado 4 species of aphids feed on fireweed, and 10 species or ants have been observed tending 3 of these species of aphids. Local populations of aphids and their associated ants were counted nondestructively at weekly intervals for up to 11 weeks. The effects of

Differences in biomass and decay rates along the elevation gradient suggest that climate warming will lead to a loss of dead wood carbon from subalpine forest.

In a laboratory experiment, female white-crowned sparrows responded almost exclusively to male songs taken from their home dialect region and usually not to songs taken from an alien dialect region. Song dialect populations may represent a level of genetic population structure below that of the subs

Experimental studies provide tests of sex-allocation theory by measuring male and female fitness gains, and examining the trade-off assumption, to show how fitness responds to shifts in allocation.

The total number of viable, undamaged seeds released by a plant provides an estimate of female reproductive success (RS). I outline a method for analyzing pollinator-mediated selection based on partitioning female RS into four multiplicative components: number of flowers, pollen received per flower,