Research in the Kapheim lab centers on the evolution of phenotypic plasticity, particularly as it applies to social behavior in bees. Our primary research objectives are to gain insights about the mechanistic underpinnings of variation in behavior, and to use these insights to investigate the evolutionary processes governing the origins, maintenance, and elaboration of social organization. We investigate these mechanisms at three levels of influence:
- Individual - Genomic and transcriptomic variation
- Internal - Host-symbiont dynamics
- External - Social environment and parental effects
Figure adapted from original images by Matt McNeil and Schwarz et al. 2007 Ann Rev Entomol
Comparative evolutionary genomics
Eusociality has evolved several times in the insect order Hymenoptera, but it is unknown whether these independent origins are derived from common evolutionary processes. We investigate the genomic underpinnings of (1) the transition from solitary life to basic forms of eusociality and (2) the transition from basic to more complex forms of eusociality in three different families of bees. We attempt to identify individual genes, gene regulatory regions, and gene networks that are evolving in association with each of these transitions. We further interrogate these genomic features to evaluate the role of natural selection and selection-mimicking neutral processes, such as recombination and mutational hotspots, in sociogenomic evolution.
Eusociality has evolved several times in the insect order Hymenoptera, but it is unknown whether these independent origins are derived from common evolutionary processes. We investigate the genomic underpinnings of (1) the transition from solitary life to basic forms of eusociality and (2) the transition from basic to more complex forms of eusociality in three different families of bees. We attempt to identify individual genes, gene regulatory regions, and gene networks that are evolving in association with each of these transitions. We further interrogate these genomic features to evaluate the role of natural selection and selection-mimicking neutral processes, such as recombination and mutational hotspots, in sociogenomic evolution.
Neuromolecular evolution of sib-social care
In eusocial bees, workers perform brood care without ever having laid eggs of their own. This sib-social care is likely derived from maternal care, but the neuromolecular mechanisms that lead to the evolution of brood care without reproductive are unknown. We use comparative transcriptomics, confocal microscopy, and behavioral experiments to investigate how the brain changes in preparation for, and in response to, brood care in bees.
In eusocial bees, workers perform brood care without ever having laid eggs of their own. This sib-social care is likely derived from maternal care, but the neuromolecular mechanisms that lead to the evolution of brood care without reproductive are unknown. We use comparative transcriptomics, confocal microscopy, and behavioral experiments to investigate how the brain changes in preparation for, and in response to, brood care in bees.
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Workers of social species, like these bumble bees (Bombus impatiens) [left] care for brood despite never having laid eggs of their own, but brood care coincides with reproduction in solitary insects, like this alfalfa leaf-cutter bee (Megachile rotundata) [right]. Illustrations by Julie Johnson, Life Science Studios.
Social and ecological drivers of life history evolution
The life history strategies of most organisms are governed by tradeoffs between investment in traits that maximize lifespan and fecundity. The queens of social insects seem to escape this tradeoff by living years or even decades longer than workers, while simultaneously laying thousands of eggs. We are investigating the mechanisms by which social insects get to break these basic rules of life by studying immunity, reproduction, and oxidative stress as a function of sociality and other ecological influences.
The life history strategies of most organisms are governed by tradeoffs between investment in traits that maximize lifespan and fecundity. The queens of social insects seem to escape this tradeoff by living years or even decades longer than workers, while simultaneously laying thousands of eggs. We are investigating the mechanisms by which social insects get to break these basic rules of life by studying immunity, reproduction, and oxidative stress as a function of sociality and other ecological influences.
Maternal behavior and the evolutionary origins of eusociality
The social environment has been theoretically demonstrated to be an important force in the evolutionary trajectory of socially expressed traits, yet empirical studies are lacking. Our previous work has demonstrated that nest foundresses of the tropical sweat bee, Megalopta genalis, can influence whether their daughters become sterile workers or future queens by manipulating the quantity and quality of larval diet. We study the physiological, transcriptomic, and adaptive basis of this variation in maternal behavior and its effects on offspring helping behavior to test the hypothesis that maternal manipulation has been an important target of selection in the evolution of eusociality.
The social environment has been theoretically demonstrated to be an important force in the evolutionary trajectory of socially expressed traits, yet empirical studies are lacking. Our previous work has demonstrated that nest foundresses of the tropical sweat bee, Megalopta genalis, can influence whether their daughters become sterile workers or future queens by manipulating the quantity and quality of larval diet. We study the physiological, transcriptomic, and adaptive basis of this variation in maternal behavior and its effects on offspring helping behavior to test the hypothesis that maternal manipulation has been an important target of selection in the evolution of eusociality.
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Megalopta genalis is an excellent model organism for the study of social evolution, because solitary and eusocial nests coexist on Barro Colorado Island, Panama [left]. Variation in larval provisions may influence the social behavior of adult bees (right]. Illustrations by Julie Johnson, Life Science Studios.
Genetic assimilation as a driver of social evolution
Phenotypic plasticity is a potentially important driver of evolution, but the processes by which environmental cues induce novel phenotypes and affect fitness are not well understood, particularly for cues from the social environment. We study the processes by which the social environment generates novel phenotypes and investigate the role of plasticity as an agent of evolutionary change, using the evolution of eusociality among bees as a case study. This research involves comparisons between facultatively eusocial bees (Megalopta genalis) and solitary bees (Nomia melanderi) within the family Halictidae.
Phenotypic plasticity is a potentially important driver of evolution, but the processes by which environmental cues induce novel phenotypes and affect fitness are not well understood, particularly for cues from the social environment. We study the processes by which the social environment generates novel phenotypes and investigate the role of plasticity as an agent of evolutionary change, using the evolution of eusociality among bees as a case study. This research involves comparisons between facultatively eusocial bees (Megalopta genalis) and solitary bees (Nomia melanderi) within the family Halictidae.
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Alkali bees (Nomia melanderi) are important alfalfa pollinators. We work with alfalfa seed growers near Walla Walla, WA to learn more about these bees. Illustration by Julie Johnson, Life Science Studios.
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Social heterosis and the social genome
Genetic effects of the social environment can influence the evolutionary trajectory of complex phenotypes. In collaboration with Peter Nonacs (UCLA), we have modeled the maintenance of genetic diversity through intergenomic epistasis. We call this social heterosis, because interacting individuals gain fitness benefits through genetic variation across different genomes at a single locus or across entire genomes. When social heterosis affects whole genomes, allelic diversity is maintained as sets of complementary (i.e. social) genomes emerge among interacting individuals. Our results match many established patterns of HIV progression, and make several novel predictions that would be otherwise masked by traditional models of disease evolution.
Genetic effects of the social environment can influence the evolutionary trajectory of complex phenotypes. In collaboration with Peter Nonacs (UCLA), we have modeled the maintenance of genetic diversity through intergenomic epistasis. We call this social heterosis, because interacting individuals gain fitness benefits through genetic variation across different genomes at a single locus or across entire genomes. When social heterosis affects whole genomes, allelic diversity is maintained as sets of complementary (i.e. social) genomes emerge among interacting individuals. Our results match many established patterns of HIV progression, and make several novel predictions that would be otherwise masked by traditional models of disease evolution.