We studied food limitation as a proximate determinant of resource allocation in social insect colonies by repeating a field experiment that had previously produced negative results. A series of plots was supplemented with food in Vermont, USA, and others were left as controls. After two years of the food supplementation, all plots were excavated and nests of Leptothorax longispinosus ants were collected. We found significant effects of the food treatment on reproductive output, male allocation ratios, and the proportion of biomass allocated to reproduction versus growth. These results contradict a previous study on the same population of these ants, and we attribute the different outcomes to annual variation in the selective regime experienced by the ants. Thus interpretation of field experiments should be couched in terms of their temporal dimensions.
Differences in colony structure between two populations of the forest ant, Myrmica punctiventris, have had dramatic consequences on allocation to growth and reproduction. A population in Vermont, in which colonies have a single, once‐mated queen, shows no evidence of inbreeding or population subdivision and has allocated 25% of sexual reproduction to males in two consecutive years. In contrast, for a population in New York that is facultatively polygynous, we have evidence of microgeographic genetic structure and inbreeding, and the populationwide allocation ratio was extremely male‐biased. Additionally, the Vermont population allocated much more energy to sexual reproduction than did the New York population. Detailed analysis of data from the Vermont population, within which colonies undergo a seasonal cycle of expansion to multiple nesting sites (polydomy), gave strong evidence of queen‐worker conflict over male allocation and indicated that workers are winning that conflict. Finally, we used contextual analysis to find that fertility selection operates almost exclusively at the level of the individual nest rather than at the higher level of the multinest colony.
The ability to recognize kin is widespread, and especially important in highly social organisms. We studied kin recognition by assessing patterns of aggression within and between nests of the ant Leptothorax longispinosus. Colonies of this species can be fractionated into subunits, a condition called polydomy. The problem of recognizing relatives is therefore more complex when those relatives can live in two or more different places. We hypothesized that spatial subdivision may have resulted in a stronger genetic component to kin recognition than in cases where colonies live in a single location. To test our hypothesis we assessed recognition capabilities for two populations of this ant that differ in the complexity of their colonies. In a New York, USA, population, polydomy is very common, and colonies also can have multiple queens. By contrast, a population in West Virginia, USA, has colonies that typically are monogynous and rarely are polydomous. We conducted introductions of ants between different nests collected in the same neighborhood, with self-introductions and alien introductions as controls. Nests from the two populations showed corresponding differences in their aggression towards intruders. For New York nests, the extent of genetic similarity was the single best predictor of aggression, whereas for West Virginia nests aggression was jointly influenced by genetic similarity and spatial distance. In both populations, we found nest pairs for which aggression was nonreciprocal; these probably reflect recognition errors by one of the nests. After the ants were maintained in the laboratory for 3 months, their aggression scores rose and fewer recognition errors were made. Thus nest-mate and colony-mate recognition in this species are mediated primarily by endogenous cues (genetic similarity); the importance of exogenous cues for nest mate recognition depends on the population's social system.
Nest locations of the forest ant Myrmica punctiventris (Roger) were mapped over the course of 2 growing seasons as part of an experiment documenting effects of food and nest site availability on social structure. Artificial hollow sticks made from dowels were used to supplement natural nest sites and to track the location of M. punctiventris nests. High numbers of nest immigrations and turnovers demonstrated that relocations of nests were more common than stasis throughout the growing season. Seasonal polydomy in M. punctiventris accounts for the seasonal pattern of expansion and contraction evident in the data. High mobility of M. punctiventris nests during the growing season and from one year to the next warrants a reevaluation of how to study the forest ant community. In particular, studies of competition in the forest ant community should not be based on inferences from spatial arrays of nests.
Purpose Multiple factors contribute to the attrition of women from STEM (science, technology, engineering, and mathematics). A lack of recognition for scholarly contributions is one piece of the puzzle. Awards are crucial not only for recognizing achievement but also for making individuals feel that their contributions are valued. Additionally, awards for research are important for promotion to various levels within the academic hierarchy, including tenure and promotion. With a grant from the National Science Foundation (NSF), the Association for Women in Science (AWIS) has been examining the ways in which women are recognized for their achievements by professional disciplinary societies.
This chapter delves into the cultural divide between academic research and commercialization. To be successful in tech transfer, researchers must understand the need to adapt to new mindsets and to learn from others with legal and business experience. The key differences between the academic culture and one that places primacy on a market-driven mindset are described, and the skills needed for team-based translation of research to the marketplace are compared and contrasted. Reward systems are incongruent between the two cultures, and understanding the inherent tension between academic and market-driven value systems is important for researchers and policymakers alike.
Polygyny, the occurrence of multiple laying queens in colonies of social insects, presents a potential challenge to our understanding of evolution by kin selection. The ant species Leptothorax longispinosus is exceptionally useful for studying this problem, since populations vary in their frequency of polygyny and queen number had previously been linked to ecological factors of density of nest sites and overwinter survival rate. In addition, colony structure is complex, with nests undergoing fissions, fusions, and worker exchanges. Here we investigate genetic and spatial structure in three North American populations of this ant. Worker-worker relatedness remains high in these populations, primarily because queen-queen relatedness is likewise high; despite considerable genetic structure within nests, however, we found no evidence of spatiogenetic structure between nests. We conclude that the nest is the functional unit of selection for these populations. Across nests, there appears to be consistent, strong, stabilizing selection for intermediate levels of polygyny in two northern populations. Variation in queen number among populations and among nests within populations thus represents the outcome of a complex interplay between genetic and ecological factors.
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