Search

Organizational scholars often adopt biological models to explain the emergence and evolution of organizations and human systems. One recent example of such adoption is the organizational ecosystem metaphor. In this article, we contend that taking a rigorous ecological approach over the application of loose ecosystem language has the potential to illuminate patterns in the life span of organizations and human systems. We first define five central properties of biological ecosystems and demonstrate their potential relevance to human-constructed systems (organizational ecosystems). We then argue the value of developing biologically based hypotheses that can be tested in the context of organizational systems. Next, we propose a set of hypotheses specific to organizational stability and disruption, using Arizona charter schools as an example to demonstrate the promise of the rigorous application of the organizational ecosystem metaphor. We close with a discussion of how the insights generated might be applied across other organizational settings and systems. [ABSTRACT FROM AUTHOR]

Causes of evolved differences in clutch size among songbird species remain debated. I propose a new conceptual framework that integrates aspects of traditional life-history theory while including novel elements to explain evolution of clutch size among songbirds. I review evidence that selection by nest predation on length of time that offspring develop in the nest creates a gradient in offspring characteristics at nest leaving (fledging), including flight mobility, spatial dispersion, and self-feeding rate. I postulate that this gradient has consequences for offspring mortality rates and parental energy expenditure per offspring. These consequences then determine how reproductive effort is partitioned among offspring, while reproductive effort evolves from age-specific mortality effects. Using data from a long-term site in Arizona, as well as from the literature, I provide support for hypothesized relationships. Nestling development period consistently explains fledgling mortality, energy expenditure per offspring, and clutch size while accounting for reproductive effort (i.e., total energy expenditure) to thereby support the framework. Tests in this article are not definitive, but they document previously unrecognized relationships and address diverse traits (developmental strategies, parental care strategies, energy requirements per offspring, evolution of reproductive effort, clutch size) that justify further investigations of hypotheses proposed here. [ABSTRACT FROM AUTHOR]

1. Hawkmoths (Sphingidae) are important plant associates at two life-history stages: larvae are herbivorous, whereas adults are nectar feeders and often pollinators. The diversity and identities of plants used for nectar is poorly known, however. 2. This study takes a community-level approach to hawkmoth nectar plant usage in a semi-arid grassland habitat in southern Arizona, U.S.A. 3. Pollen carried on the proboscis was identified from over 700 individuals of 14 hawkmoth species attracted to lights over a 2-year period. 4. Two plant species dominated pollen loads, suggesting that hawkmoths use these species extensively as nectar sources: Datura wrightii (Solanaceae), a classic hawkmoth-pollinated plant, and Agave palmeri (Agavaceae), which is known to be used extensively by bats. Field surveys indicate that both species are relatively rare in the flowering community. Little or no pollen was present on the moths from the most common plant species in flower during the study. 5. The dominance of Agave in pollen loads suggests that this typically bat-pollinated species may be subsidising pollinator populations of the hawkmoth-pollinated flora. 6. Three groups of hawkmoths within this community are identified based on larval diets (reported in the literature) and adult diets (documented here): those that, at a given site, heavily exploit the same plant species at both life-history stages ( Manduca sexta and M. quinquemaculata); those that have broad local associations at both life-history stages ( Hyles lineata); and those that exhibit narrow but non-overlapping local associations at the two life-history stages (all other hawkmoths at this site). [ABSTRACT FROM AUTHOR]

Pollinator attraction, pollen limitation, resource limitation, pollen donation and selective fruit abortion have all been proposed as processes explaining why hermaphroditic plants commonly produce many more flowers than mature fruit. We conducted a series of experiments in Arizona to investigate low fruit-to-flower ratios in senita cacti, which rely exclusively on pollinating seed-consumers. Selective abortion of fruit based on seed predators is of particular interest in this case because plants relying on pollinating seed-consumers are predicted to have such a mechanism to minimize seed loss. Pollinator attraction and pollen dispersal increased with flower number, but fruit set did not, refuting the hypothesis that excess flowers increase fruit set by attracting more pollinators. Fruit set of natural- and hand-pollinated flowers were not different, supporting the resource, rather than pollen, limitation hypothesis. Senita did abort fruit, but not selectively based on pollen quantity, pollen donors, or seed predators. Collectively, these results are consistent with sex allocation theory in that resource allocation to excess flower production can increase pollen dispersal and the male fitness function of flowers, but consequently results in reduced resources available for fruit set. Inconsistent with sex allocation theory, however, fruit production and the female fitness function of flowers may actually increase with flower production. This is because excess flower production lowers pollinator-to-flower ratios and results in fruit abortion, both of which limit the abundance and hence oviposition rates, of pre-dispersal seed predators. [ABSTRACT FROM AUTHOR]

The application of ecological concepts and principles to the study of organization design and system development is now commonplace. Population ecology is one biological perspective that has been especially influential within the organization design literature. In the current study, we illustrate for the first time how this framework can be used to reveal when and in what ways intervention is warranted within a system that, like a biological population in nature, has emerged with little to no purposeful design. Specifically, we use 20 years of data on 1,074 Arizona charter schools to illustrate how population analysis can be used to uncover the characteristics of individual organizations that have the highest ability to survive over time within systems that have been allowed to emerge with little to no purposeful design. Our findings lead us to argue how pre-intervention population analysis at the system level can influence organization-level design choices in a way that enables dynamic fit and thereby enhances the likelihood of organization survivorship and innovation over time. [ABSTRACT FROM AUTHOR]

Studies of plant–pollinator interactions have often documented species differences in preferences for floral advertisements and rewards. However, the contribution of intraspecific variation in behaviours, especially between sexes, remains less understood. We explored resource preference and resource use by male and female Manduca sexta hawkmoths, relative to two important nectar resources in southern Arizona, U.S.A. Manduca sexta is the major pollinator of one of these species (Datura wrightii, Solanaceae). Because females must also seek out D. wrightii as an oviposition resource, females were predicted to feed upon it more than would males, which should be free to choose the best nectar resource. Using naïve laboratory-reared moths in flight arena experiments, we found that both sexes preferred Datura wrightii over Agave palmeri (Agavaceae). Exposure to only one species and an odourless paper control, however, revealed sex-specific differences in foraging behaviour, with females feeding longer from A. palmeri and males feeding longer from D. wrightii, leading us to reject our hypothesis. Differences in feeding preferences directly translated into differences in energy intake. Females gained significantly more energy than did males by feeding from A. palmeri. We also examined whether behavioural preferences of moths in the laboratory translated into foraging behaviour in the field. Pollen load analysis of moths caught in 2004 showed that females carried significantly more A. palmeri pollen than did males, whereas males carried more D. wrightii pollen than did females. Whereas most studies examine pollination associations at the species level, our results highlight the potential importance of between-sex variation in floral visits. [Copyright &y& Elsevier]

Mutualism is an often complex interaction among multiple species, each of which may respond differently to abiotic conditions. The effects of temperature on the formation, dissolution, and success of these and other species interactions remain poorly understood. We studied the thermal ecology of the mutualism between the cactus Ferocactus wislizeni and its ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plants and, in exchange, protect the plants from herbivores; there is a hierarchy of mutualist effectiveness based on aggression toward herbivores. We determined the relationship between temperature and ant activity on plants, the thermal tolerance of each ant species, and ant activity in relation to the thermal environment of plants. Temperature played a role in determining which species interact as mutualists. Three of the four ant species abandoned the plants during the hottest part of the day (up to 40 °C), returning when surface temperature began to decrease in the afternoon. The least effective ant mutualist, F. pruinosus, had a significantly higher critical thermal maximum than the other three species, was active across the entire range of plant surface temperatures observed (13.8-57.0 °C), and visited plants that reached the highest temperatures. F. pruinosus occupied some plants full-time and invaded plants occupied by more dominant species when those species were thermally excluded. Combining data on thermal tolerance and mutualist effectiveness provides a potentially powerful tool for predicting the effects of temperature on mutualisms and mutualistic species.