Recognizing danger: innate and learned information
Animals live in a dangerous world. It's full of predators, and even prey might fight back. When one mistake can be deadly, how do animals recognize what's safe and what's not?
Our lab integrates behavioral ecology and neurobiology to understand how species avoid making costly mistakes. We study the ability of some birds to recognize specific threats without prior experience, i.e. innately. We measure behaviors of wild birds towards replicas of dangerous predators and prey in the field. Then we precisely quantify the cues that elicit those behavior in the lab using hand-raised birds that have never encountered danger. We also test the relationship between innate biases towards/against certain cues and subsequent learning. We measure how learned and innate responses stimulate neural activity. This program lets us connect innate and learned behaviors with specific brain regions to understand how genes and experience produce adaptive fear responses. Armed with this knowledge, we will be better prepared to predict how animals will deal with danger as their distributions shift and novel species invade their ranges. Just as importantly, it will improve our fundamental understanding of how brains process fear.
Our lab integrates behavioral ecology and neurobiology to understand how species avoid making costly mistakes. We study the ability of some birds to recognize specific threats without prior experience, i.e. innately. We measure behaviors of wild birds towards replicas of dangerous predators and prey in the field. Then we precisely quantify the cues that elicit those behavior in the lab using hand-raised birds that have never encountered danger. We also test the relationship between innate biases towards/against certain cues and subsequent learning. We measure how learned and innate responses stimulate neural activity. This program lets us connect innate and learned behaviors with specific brain regions to understand how genes and experience produce adaptive fear responses. Armed with this knowledge, we will be better prepared to predict how animals will deal with danger as their distributions shift and novel species invade their ranges. Just as importantly, it will improve our fundamental understanding of how brains process fear.
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Information in ecology
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Warning signals are adaptations of defended prey that tell predators not to attack them. If they evolve, they must be favored by individual-level selection, but we do not their subsequent impacts on populations and communities. We've developed theory to illustrate some of the possibilities (Kikuchi et al. 2021 Biological Reviews, Kikuchi et al. American Naturalist 2022).
We're testing these theories using massive datasets of diet information. If theory proves true, then the evolution of warning signals and other traits such as floral signals lends structure to predator-prey and plant-pollinator networks. |
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An important type of information exchanged between animals is social: many animals learn from each other. What they learn can have ecological relevance, such as how to exploit a novel prey item or how to exploit a current prey item more efficiently. This is called innovation, which can have a host of ecological consequences. Social learning of innovations means that they can spread like a virus!
We model how social learning of innovations impacts predator-prey communities. An important result is that innovation can destabilize ecological communities. This can mean cyclic dynamics in populations of predators and prey, or the extinction of native prey species when local predators start eating an invasive prey. It's critical to consider how information flows through an ecosystem if we're going to make informed predictions about its future.
We model how social learning of innovations impacts predator-prey communities. An important result is that innovation can destabilize ecological communities. This can mean cyclic dynamics in populations of predators and prey, or the extinction of native prey species when local predators start eating an invasive prey. It's critical to consider how information flows through an ecosystem if we're going to make informed predictions about its future.
Information in evolution
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If you were a predator trying to figure out what to eat in your community, how would you change your behavior as its diversity increased? This question is important if we want to understand how mimicry evolves in different communities. When prey are diverse, to make perfect decisions, predators would need to sample many different kinds of prey (risky!), and invest a lot in memorization. Instead, predators could economize with simple rules to identify prey. Work in eLife shows that imperfect mimicry is favored in diverse communities. Both high species richness and high species evenness increase selection for mimicry. This occurs because predators rely more on simple rules-of-thumb to generalize prey, such as “avoid red things”. Consequently, mimicry can evolve easily. For an overview of warning signals in ecological communities, check out this review.
The psychology of predators can be a powerful force driving prey phenotype. In the American southeast, scarlet kingsnakes mimic venomous coral snakes. The two snakes can be told apart with the rhyme "red touches yellow, kill a fellow; red touches black, you're okay Jack!" Do predators in the wild use this information to make adaptive dietary decisions? We found that the ratio of red:black on the dorsum of scarlet kingsnakes was sufficient to protect them as well as coral snakes. Predators ignore ring order, facilitating the evolution of imperfect mimicry in the scarlet kingsnake! |
In simple community 1, predators can memorize all prey, so imperfect mimics stand out. But in community 2, they may instead switch to a simple rule: “avoid red.”
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Mimics may converge on the phenotypes of their models using novel developmental systems. This may be necessary if unique structures or pigments are used in warning signals. It may also filter the species that can evolve to become mimics. Alternatively, mimicry may be widespread if mimics can co-opt deeply conserved developmental pathways to produce signals similar to those of their models. Coral snakes and their mimics use a color production system that is found among most snakes, perhaps explaining why about 20% of New World snakes mimic coral snakes.
The clusters of white crystals in this cross section of yellow skin from a scarlet kingsnake are made from guanine. Their disorganized structure and small size reflects mainly short wavelengths.
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Organic (top) and aqueous (bottom) pigment extracts from an eastern coral snake. Pink indicates the presence of drosopterins, the pigments responsible for the bright red hues of their warning signals.
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