On Caste Ratios in Ant Colonies: Population Responses to Changing Environments

Herbers, Joan M.

doi:10.1111/j.1558-5646.1980.tb04845.x

Cited by 27 publications

(16 citation statements)

References 11 publications

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“…Rather than responding to variable fat storage needs through alteration of the physical caste proportions of minors and majors, colonies of P. morrisi flexibly change the allocation of workers to tasks within their behavioral repertoire. This kind of extensive behavioral plasticity in worker demography has been well-documented in other ants (Davidson, 1978;Herbers, 1980;Calabi, 1988;Calabi and Traniello, 1989;Gordon, 1989, Brown and Traniello, 1998, McGlynn and Owen, 2002. The results of this study are significant in demonstrating that a given mode of behavioral plasticity, in this case nutrient storage, may operate on large geographic scales according to local conditions.…”

supporting

confidence: 54%

Seasonality, division of labor, and dynamics of colony-level nutrient storage in the ant Pheidole morrisi

Yang

2006

Insect. Soc.

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Nutritional provisioning is a critical component of life history strategies, and of particular interest in social insect colonies because of the role that division of labor plays in resource allocation. To explore the mechanisms that underlie colony nutritional strategies, I examined three populations of the ant Pheidole morrisi across a gradient of overwinter food scarcity over two seasons. P. morrisi colonies were found to employ a mixed strategy of fat storage with regard to a longer overwinter period: members of both worker castes increase their percent-fat in a graded manner, while the proportion of a specialized subcaste of majors known as "repletes", also increased within the colony. Geographic variation in other colony traits such as mean colony size, mean worker size, and minor/major caste ratio were also found, although not always in a manner clearly relating to fat storage. These results indicate that colony demography responds to seasonal fluctuations in food availability through behavioral alterations (increased fat stores and recruitment of replete workers) rather than physical alterations (changes in lean body sizes or caste ratio). The findings illustrate the dynamic role division of labor plays in the success of insect colonies confronting environmental variability.

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supporting

confidence: 54%

Seasonality, division of labor, and dynamics of colony-level nutrient storage in the ant Pheidole morrisi

Yang

2006

Insect. Soc.

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“…More recently, others have examined the size variation within (Goulson, 2003; Peat et al , 2005b) and between (Peat et al , 2005a) species, but this was less on the ontogeny of the distribution and more on the role of size polymorphism in the division of labour. Previous work has suggested that size variation in ants might be a result of limited food availability (Herbers, 1980; Rissing, 1987), as colonies, when resources are not limited, produce overall larger workers and fewer small ones. In contrast, we show here that in bumble bees, worker size variation is still present with unlimited resources.…”

Section: Discussionmentioning

confidence: 99%

Ontogeny of worker body size distribution in bumble bee (Bombus impatiens) colonies

Couvillon

Jandt

Duong

2010

Ecological Entomology

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Bumble bees exhibit worker size polymorphisms; highly related workers within a colony may vary up to 10-fold in body mass. As size variation is an important life history feature in bumble bees, the distribution of body sizes within the colony and how it fluctuates over the colony cycle were analysed.Ten commercially purchased colonies of Bombus impatiens (Cresson) were reared in ad libitum conditions. The size of all workers present and newly emerging workers (callows) was recorded each week.The average size of bumble bee workers did not change with colony age, but variation in body size tended to decrease over time. The average size of callows did not change with population size, but did tend to decrease with colony age. In all measures, there was considerable variation among colonies.Colonies of B. impatiens usually produced workers with normally distributed body sizes throughout the colony life cycle. Unlike most polymorphic ants, there was no increase in worker body size with colony age or colony size. This provides the first, quantitative data on the ontogeny of bumble bee worker size distribution. The potential adaptive significance of this size variation is discussed.

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“…stage, nanitic workers benefit a colony because of their numbers, not their individual efficiency (Porter and Tschinkel 1986). Similarly, colonies may respond to environmental stress by reducing worker size variance and rearing workers of intermediate size (Herbers 1980). Mature colonies of Messor (= Veromessor) pergandei may need to maintain worker numbers rather than worker size during predictable seasonal food shortages (Rissing 1987).…”

Section: Colony Phenotypes and Correlates Of Worker Body Sizementioning

confidence: 99%

The Adaptiveness of Worker Demography in the Attine Ant Trachymyrmex Septentrionalis

Bershers

Traniello

1994

Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Caste theory states that worker size distributions in ant colonies have evolved for efficient division of labor and predicts that they should vary with habitat and have an effect on fitness. We tested these predictions in a comparative study of worker size variation and colony fitness in Florida and Long Island populations of Trachymyrmex septentrionalis. Colonies from the two populations were excavated shortly before the time of the mating flights, so that workers and reproductive forms could be censused. We measured worker head widths in each colony and analyzed the resulting size frequency distributions using the mean, standard deviation, skewness, and kurtosis, and also principal components derived from these parameters. Size frequency distributions were unimodal and close to normal, with a tendency to negative skewness. Colonies in the Long Island population had both larger workers and greater size variation than those in Florida. Florida colonies followed a growth trajectory in which the mean and standard deviation of worker head width both increased with colony size, whereas in Long Island there was an inverse relationship between the mean and standard deviation that was independent of colony size. Analysis based on the principal components showed that worker size variation significantly affected fitness in both populations, and this was not a secondary effect of colony size. Population differences in colony life history strategies may account for the observed patterns: the Long Island population appears to be adapted for surviving the winter diapause, while the Florida population has experienced different selective pressures, possibly for rapid colony growth. Size variation that has evolved in the context of life history strategies may serve as a preadaptation for division of labor.

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On Caste Ratios in Ant Colonies: Population Responses to Changing Environments

Cited by 27 publications

References 11 publications

Seasonality, division of labor, and dynamics of colony-level nutrient storage in the ant Pheidole morrisi

Seasonality, division of labor, and dynamics of colony-level nutrient storage in the ant Pheidole morrisi

Ontogeny of worker body size distribution in bumble bee (Bombus impatiens) colonies

The Adaptiveness of Worker Demography in the Attine Ant Trachymyrmex Septentrionalis

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