Karen L. Hollis’s research while affiliated with Mount Holyoke College and other places

Evolution of Learning and Memory Mechanisms is an exploration of laboratory and field research on the many ways that evolution has influenced learning and memory processes, such as associative learning, social learning, and spatial, working, and episodic memory systems. This volume features research by both outstanding early-career scientists as well as familiar luminaries in the field. Learning and memory in a broad range of animals are explored, including numerous species of invertebrates (insects, worms, sea hares), as well as fish, amphibians, birds, rodents, bears, and human and nonhuman primates. Contributors discuss how the behavioral, cognitive, and neural mechanisms underlying learning and memory have been influenced by evolutionary pressures. They also draw connections between learning and memory and the specific selective factors that shaped their evolution. Evolution of Learning and Memory Mechanisms should be a valuable resource for those working in the areas of experimental and comparative psychology, comparative cognition, brain–behavior evolution, and animal behavior.

Evolution of Learning and Memory Mechanisms is an exploration of laboratory and field research on the many ways that evolution has influenced learning and memory processes, such as associative learning, social learning, and spatial, working, and episodic memory systems. This volume features research by both outstanding early-career scientists as well as familiar luminaries in the field. Learning and memory in a broad range of animals are explored, including numerous species of invertebrates (insects, worms, sea hares), as well as fish, amphibians, birds, rodents, bears, and human and nonhuman primates. Contributors discuss how the behavioral, cognitive, and neural mechanisms underlying learning and memory have been influenced by evolutionary pressures. They also draw connections between learning and memory and the specific selective factors that shaped their evolution. Evolution of Learning and Memory Mechanisms should be a valuable resource for those working in the areas of experimental and comparative psychology, comparative cognition, brain–behavior evolution, and animal behavior.

Despite being simultaneously male and female, hermaphrodites may still need to assume the male or female sexual role in a mating encounter, with the option to swap roles afterwards. For the great pond snail, Lymnaea stagnalis, deciding which sexual role to perform has important consequences, since sperm transfer and male reproductive success can be decreased. We hypothesised that detecting cues that indicate a possible mating encounter could help them to adapt their mating behaviour. Therefore, we experimentally assessed whether signalling the presence of a conspecific with an odour can affect the sexual role of Lymnaea stagnalis. The results showed that learning resulted in either an increased ability to mate as a male or in faster mating compared to the control group. These findings reveal that learning shapes the mating dynamics of Lymnaea stagnalis, thus showing that cognitive processes not only affect mating in separate-sexed species but also in hermaphrodites.

Evolution of Learning and Memory Mechanisms is an exploration of laboratory and field research on the many ways that evolution has influenced learning and memory processes, such as associative learning, social learning, and spatial, working, and episodic memory systems. This volume features research by both outstanding early-career scientists as well as familiar luminaries in the field. Learning and memory in a broad range of animals are explored, including numerous species of invertebrates (insects, worms, sea hares), as well as fish, amphibians, birds, rodents, bears, and human and nonhuman primates. Contributors discuss how the behavioral, cognitive, and neural mechanisms underlying learning and memory have been influenced by evolutionary pressures. They also draw connections between learning and memory and the specific selective factors that shaped their evolution. Evolution of Learning and Memory Mechanisms should be a valuable resource for those working in the areas of experimental and comparative psychology, comparative cognition, brain–behavior evolution, and animal behavior.

Evolution of Learning and Memory Mechanisms is an exploration of laboratory and field research on the many ways that evolution has influenced learning and memory processes, such as associative learning, social learning, and spatial, working, and episodic memory systems. This volume features research by both outstanding early-career scientists as well as familiar luminaries in the field. Learning and memory in a broad range of animals are explored, including numerous species of invertebrates (insects, worms, sea hares), as well as fish, amphibians, birds, rodents, bears, and human and nonhuman primates. Contributors discuss how the behavioral, cognitive, and neural mechanisms underlying learning and memory have been influenced by evolutionary pressures. They also draw connections between learning and memory and the specific selective factors that shaped their evolution. Evolution of Learning and Memory Mechanisms should be a valuable resource for those working in the areas of experimental and comparative psychology, comparative cognition, brain–behavior evolution, and animal behavior.

In a species of Mediterranean desert-dwelling ant, Cataglyphis piliscapa (formerly, C. cursor), some individuals, mostly foragers, engage in highly orchestrated behavior to free a trapped nestmate. Their behavior, which we have labeled rescue, is a heritable trait in this species, and it appears fully formed within a few days of an ant’s emergence as an adult. Not only is the rescue behavior by these ant specialists precisely targeted, but also it involves a complex, dynamic sequence of behavioral patterns. That is, each rescue operation is responsive both to the specific circumstances of the nestmate’s entrapment and to the way in which that particular rescue operation unfolds, relying on the rescuer’s short-term memory of its previous actions to increase efficiency and to decrease energy expenditure. Rescue appears in several other ant species as well, and, although the specific behavioral patterns and contexts vary across species, the outcome—namely, releasing a distressed nestmate—remains the same. Here, we describe research designed to address questions about the function, evolution, cause, and development of rescue behavior in C. piliscapa—a behavior ecological approach—drawing on research in other species, and by other researchers, both to highlight comparative similarities and differences and, importantly, to draw attention to still unanswered questions. In addition, by shedding light on the rescue behavior of ants, we also hope to engender increased attention to, and research on, this extraordinary form of helping behavior in multiple other taxa.

Previous research in our laboratories has demonstrated that, within each colony of Cataglyphis piliscapa (formerly C. cursor) ants, only some individuals are capable of performing a complex sequence of behavioral patterns to free trapped nestmates—a sequence that not only is memory-dependent but also is responsive to the particular circumstances of that entrapment and how the rescue operation unfolds. Additionally, this rescue behavior is inherited patrilineally from but a few of the many males that fertilize the eggs of the colony’s single queen. Here, we describe three experiments to explore rescue behavior further—namely, whether rescuers are in any way selective about which nestmates they help, how the age of rescuers and the victims that they help affect the quantity and quality of the rescue operation, and when this complex behavior first emerges in an ant’s development. Taken together with the previous heritability analysis, these behavioral experiments provide clear evidence that the ability to rescue nestmates in distress should be recognized as a specialization, which together with other specialized tasks in C. piliscapa, contributes to a division of labor that increases the efficiency of the colony as a whole and, thus increases its reproductive success.

In colonies of Cataglyphis cursor ants, a single queen mates with multiple males, creating the foundation for heritable behavioral specializations. A novel and unique candidate for such specializations is rescue behavior, a precisely delivered form of altruism in which workers attempt to release trapped nestmates and which relies on short-term memory of previous actions to increase its efficiency. Consistent with task specialization, not all individuals participate; instead, some individuals move away from the victim, which gives rescuers unrestricted access. Using a bioassay to identify rescuers and non-rescuers, coupled with paternity assignment via polymorphic microsatellite markers, we not only show that rescue behavior is heritable, with 34% of the variation explained by paternity, but also establish that rescue, heretofore overlooked in analyses of division of labor, is a true specialization, an ant version of first responders. Moreover, this specialization emerges as early as 5 days of age, and the frequency of rescuers remains constant across ants' age ranges. The extremely broad range of these ants' heritable polyethism provides further support for the critical role of polyandry in increasing the efficiency of colony structure and, in turn, reproductive success.