Recent achievements for the campus community were earned by Allison Barnes, Marques Garrett, Michael Hanus, Courtney Herber, Anna Lampe, Mary Lenz, Wataru Nilmori, Naisargi Nitinkumar, Aryamav Patnaik, James Schnable, Kimberly Stanke, Adam Wagler, Bryan Wang, Changmin Yan, Rami Ziara, Child, Youth and Family Studies, and the National Student Advertising Competition Team.
Nebraska's Kate Lyons has co-authored a new study suggesting that ancient humans began hunting large mammal species to extinction at least 90,000 years earlier than once thought.
Birds of a feather may flock together, but the makeup of the flock is always changing.
Population turnover — a universal process driven by birth, death, migration and dispersal — affects social networks of all kinds, from human to bird to cell. Despite these demographic swings, many species’ social networks remain intact across time. Nebraska evolutionary ecologist Dai Shizuka first noticed this phenomenon while studying golden-crowned sparrows in California as a doctoral student.
“I saw a long-term stability to the social system, even though half the birds were replaced each year,” said Shizuka, assistant professor of biological sciences at the University of Nebraska–Lincoln. “This raised the question: How do societies remain stable despite the constant replacement of individuals?”
This query planted the seed for a research trajectory he will explore with a five-year, $712,500 Faculty Early Career Development award from the National Science Foundation. Through the lens of ornithology — the study of birds — Shizuka is studying how population turnover shapes social networks, network resilience and the relationship between social structure and social behavior.
His work will pave the way to a better understanding of how both disease and information spread through populations, as social relationships are a prerequisite to transmitting pathogens or facts. It may shed light on how social relationships affect evolution. And it could lay the foundation for assessing the stability of social networks across the spectrum, from humans to other animals to genes.
In recent years, animal behavior researchers have increasingly used social network analysis to investigate populations of various species. By mapping data points on graphs, researchers can better identify connections and relationships among individuals within the network. But to date, no one has comprehensively studied how ever-changing membership affects these networks, or why societies persist in the face of demographic change. This is a crucial piece of the puzzle, Shizuka said.
“When a group loses an individual, all of that individual’s social connections and relationships are also lost,” he said. “The replacement individual makes completely new connections that didn’t exist before. This process is ubiquitous in all social networks.”
To study these patterns, Shizuka takes a two-pronged approach. He is developing a model of network dynamics using computational programming, which allows him to simulate theoretical scenarios involving population turnover. Using this model, he assigns various traits to individuals or groups within a network and tests how they are affected by demographic shifts.
Simultaneously, he leverages his ongoing field research on golden-crowned sparrows at the University of California, Santa Cruz to study links between population turnover and social selection. For example, he is building on recent research investigating how social recognition, in addition to physical traits such as plumage size, dictate which individuals win in competitions for food and other resources, which could have evolutionary implications.
Other facets of Shizuka’s project involve launching an annual on-campus event that will expose refugee and immigrant high school students in Lincoln to opportunities at the university, with the aim of recruiting more of them to campus and increasing their representation in the STEM fields. He also is developing undergraduate and graduate curricula focused on reproducible research.
National Science Foundation CAREER grants support pre-tenure faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research.
Birds of a feather may flock together, but the makeup of the flock is always changing.
Population turnover — a universal process driven by birth, death, migration and dispersal — affects social networks of all kinds, from human to bird to cell. Despite these demographic swings, many species’ social networks remain intact across time. Nebraska evolutionary ecologist Dai Shizuka first noticed this phenomenon while studying golden-crowned sparrows in California as a doctoral student.
“I saw a long-term stability to the social system, even though half the birds were replaced each year,” said Shizuka, assistant professor of biological sciences at the University of Nebraska–Lincoln. “This raised the question: How do societies remain stable despite the constant replacement of individuals?”
This query planted the seed for a research trajectory he will explore with a five-year, $712,500 Faculty Early Career Development award from the National Science Foundation. Through the lens of ornithology — the study of birds — Shizuka is studying how population turnover shapes social networks, network resilience and the relationship between social structure and social behavior.
His work will pave the way to a better understanding of how both disease and information spread through populations, as social relationships are a prerequisite to transmitting pathogens or facts. It may shed light on how social relationships affect evolution. And it could lay the foundation for assessing the stability of social networks across the spectrum, from humans to other animals to genes.
In recent years, animal behavior researchers have increasingly used social network analysis to investigate populations of various species. By mapping data points on graphs, researchers can better identify connections and relationships among individuals within the network. But to date, no one has comprehensively studied how ever-changing membership affects these networks, or why societies persist in the face of demographic change. This is a crucial piece of the puzzle, Shizuka said.
“When a group loses an individual, all of that individual’s social connections and relationships are also lost,” he said. “The replacement individual makes completely new connections that didn’t exist before. This process is ubiquitous in all social networks.”
To study these patterns, Shizuka takes a two-pronged approach. He is developing a model of network dynamics using computational programming, which allows him to simulate theoretical scenarios involving population turnover. Using this model, he assigns various traits to individuals or groups within a network and tests how they are affected by demographic shifts.
Simultaneously, he leverages his ongoing field research on golden-crowned sparrows at the University of California, Santa Cruz to study links between population turnover and social selection. For example, he is building on recent research investigating how social recognition, in addition to physical traits such as plumage size, dictate which individuals win in competitions for food and other resources, which could have evolutionary implications.
Other facets of Shizuka’s project involve launching an annual on-campus event that will expose refugee and immigrant high school students in Lincoln to opportunities at the university, with the aim of recruiting more of them to campus and increasing their representation in the STEM fields. He also is developing undergraduate and graduate curricula focused on reproducible research.
National Science Foundation CAREER grants support pre-tenure faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research.
Birds of a feather may flock together, but the makeup of the flock is always changing.
Population turnover — a universal process driven by birth, death, migration and dispersal — affects social networks of all kinds, from human to bird to cell. Despite these demographic swings, many species' social networks remain intact across time. Nebraska evolutionary ecologist Dai Shizuka first noticed this phenomenon while studying golden-crowned sparrows in California as a doctoral student.
A new study from the University of Nebraska-Lincoln has shown that it’s possible to feed two birds with one hormone.
The hormone, mesotocin, has a closely related cousin — oxytocin — that decades of research suggests can promote prosocial behavior in mammals: stronger affiliations among dogs, greater acts of charity among humans.
Nebraska researchers Juan Duque and Jeffrey Stevens set out to determine whether mesotocin could do the same for birds — specifically pinyon jays, a highly social species known to share food with one another in the wild.
After giving pinyon jays a high dose of mesotocin in the lab, Duque and Stevens found that food sharing among the birds rose by nearly 32 percent. That compared with a 12-percent rise when administering a lower dose.
“We’re seeing a very similar (prosocial) effect using a slightly different molecule, which points to the fact that this is a really important hormone that has effects across a large range of species,” said Stevens, associate professor of biology and psychology.
“When you think about prosocial behavior, the emphasis is on chimps, monkeys — it’s all primates — and recently dogs,” Stevens said. “We know that primates have pretty sophisticated cognition. We know that dogs evolved to have special interactions with humans. But when you jump to birds, you’re now talking about broad-scale kinds of effects.”
To assess the effects of mesotocin, the team set up three adjacent cages. The pinyon jay being tested in a given experiment was placed in the center cage, with a neighboring jay put in either the left or right cage. After being trained, the center jay could choose to peck one of two wires — one slightly to the left, one to the right — that were respectively connected to a left and right tray outside of the cages.
Each tray held two food dishes, which were positioned so that the two centermost dishes sat in front of the center cage and the outermost dishes faced the left and right cages, respectively. When a center jay pecked the left or right wire, the researchers pushed forward the corresponding tray, giving the jays access to those dishes.
In one experiment, the team filled all four dishes with a mealworm. The center jay received a worm no matter which tray it chose, but that choice also determined whether a second worm went to the neighboring jay or an empty cage, making it a test of prosocial behavior.
The team also evaluated altruistic behavior by placing mealworms only in the outermost dishes, meaning that the center jay could deliver a worm to either its neighbor or an empty cage — but received no worm for itself in either case. Under those conditions, Duque and Stevens found that the center jays did not care whether they delivered food to their neighbor or the empty cage, and even a large dose of mesotocin failed to spur a meaningful rise in this altruism.
But by establishing a link between the hormone and generosity, Duque said, the study could accelerate experimental research on prosocial behavior beyond the realm of primates and other mammals.
“Birds are much more feasible to work with in many circumstances, and you have access to many more species that vary along the sociality spectrum (and) show varying evidence of prosocial behaviors,” said Duque, a doctoral student in psychology. “I think there’s an opportunity to run wild with it.
“And further investigations of mesotocin in avian prosocial behavior could start to demonstrate some of these widespread effects, which tells us that there must be something (special) going on with the structure of this hormone and what it’s doing biochemically.”
Duque and Stevens authored the study with Nebraska alumnae Whitney Leichner and Holly Ahmann, former undergraduate members of Stevens’ Adaptive Decision-Making Lab. The team reported its findings in the journal Biology Letters and received support from the National Science Foundation.