Genomic and neurobiological bases of variation in fighting strategies in gamecocks

Molecular Biology and Evolution · 2026-01-01 · 1 citations

Aggression is an essential animal behavior for survival, particularly in situations where fighting cannot be avoided. In such situations, the choice of fighting strategy (eg biting, charging, or defending) is critical. Although the molecular bases of fighting and aggressiveness have been previously studied, how genetic, transcriptional, and neurobiological mechanisms contribute to the choice of fighting strategy remains largely unknown. Here, we use two subpopulations of chickens bred for cockfighting that show markedly different fighting strategies: offensive and defensive attack. A genome-wide screen comparing individuals from the two subpopulations indicated a polygenic background and we identified 15 candidate genes, five of which are implicated in neuronal development. Among these, the transcription factor gene FOXP1 was notable. FOXP1 is essential for neuronal development in the brain and has been implicated in the regulation of motor circuits. Transcriptomic analysis of the diencephalon also revealed differential expressions of genes involved in neurodevelopment, as well as in the synthesis and release of neurotransmitters. RNA-sequencing and immunohistochemistry suggested that activation of the indirect pathway of the brain motor circuit promotes the defensive fighting strategy. This was further supported by behavioral pharmacological experiments targeting dopaminergic signaling. Taken together, our results indicate that genomic variation and altered expression of neurodevelopment-related genes underlie differences in fighting strategies, and that the neuroendocrine changes in brain circuits further modulate these behavioral outcomes.

Hippocampal representations of partner and novel individuals in monogamous California mice during pair bond formation

bioRxiv (Cold Spring Harbor Laboratory) · 2026-05-09

ABSTRACT The hippocampal CA2 region is critical for social novelty recognition memory—the discrimination of whether a conspecific is novel or familiar. However, its role in forming a memory of a pair-bonded mate is unknown. To examine how social memories of pair-bonded individuals are encoded, we sought to understand if CA2 and the neighboring CA1 region participate in the memorization and recognition of a pair-bonded mate in monogamous Peromyscus californicus (California mice). Here, we report that CA2 and CA1 show distinct changes in social encoding of an opposite sex conspecific following pair-bonding. Using multi-channel silicon probes, we recorded single units from CA2 and CA1 in freely behaving male mice before and after pair bond formation during interactions with novel and partner females. We found that the strength of CA2 representations of a novel female mouse weakened after pair bond formation, indicating that CA2 may be preferentially important for novelty detection. In contrast, CA1 demonstrated an increase in the strength of encoding a female partner after pair-bond formation, suggesting that CA1 may encode partner memory. These findings indicate that pair bonding shifts the discrimination of social information from CA2 to CA1.

Retinoic acid production via the ray-finned fish gene <i>bco1l</i> is essential for juvenile development

Genetics · 2026-02-26

In vertebrates, vitamin A (VA) is crucial for development, tissue homeostasis, vision, and immunity. Retinal, a form of VA, can be produced via enzymatic cleavage of β-carotene by beta-carotene oxygenase 1 (bco1) and bco1-like (bco1l), but the developmental and tissue-specific functions of these genes are poorly understood. While bco1 is found across vertebrate taxa, bco1l is a paralog of bco1 that we discover to have evolved in the ray-finned fishes, the most abundant, speciose, and commercially important group of fishes. We investigated the function of bco1l in ray-finned Siamese fighting fish, commonly known as betta, an emerging model for genetics and development. Using CRISPR/Cas9 knockouts, we find that lack of bco1l results in reduced VA and elevated β-carotene in larvae, starting when animals have exhausted their yolk supply of retinal, followed by stunted growth and death during juvenile development. Exogenous retinoic acid largely rescues the mutation, demonstrating its deficiency causes these defects. bco1l is 7× more abundant than bco1 in the intestine. This, coupled with the inability of bco1 to sustain VA production in the bco1l mutant, indicates that bco1l is the primary enzyme for dietary carotenoid conversion into retinal. Our results show that VA production by bco1l is required for post-embryonic development, and that bco1l became essential after evolving via duplication of bco1.

Evolution: Poison frogs changing colors while island hopping

Current Biology · 2026-03-01

Coordination and persistence of aggressive visual communication in Siamese fighting fish

Cell Reports · 2025-01-01 · 4 citations

Outside acoustic communication, little is known about how animals coordinate social turn taking and how the brain drives engagement in these social interactions. Using Siamese fighting fish (Betta splendens), we discover dynamic visual features of an opponent and behavioral sequences that drive visually driven turn-taking aggressive behavior. Lesions of the telencephalon show that it is unnecessary for coordinating turn taking but is required for persistent participation in aggressive interactions. Circumscribed lesions of the caudal dorsomedial telencephalon (cDm; the fish pallial amygdala) recapitulated the telencephalic lesions. Furthermore, ventral telencephalic regions and the thalamic preglomerular complex, all of which project to cDm, show increased activity during aggressive interactions. Our work highlights how dynamic visual cues shape the rhythm of social interactions at multiple timescales. The results point to the vertebrate pallial amygdala as a region with an evolutionarily conserved role in regulating the persistence of emotional states, including those that promote engagement in social interactions.

Retinoic acid production via the ray-finned fish gene <i>beta-carotene oxygenase 1-like</i> is essential for juvenile development

bioRxiv (Cold Spring Harbor Laboratory) · 2025-10-04 · 1 citations

Abstract In vertebrates, vitamin A (VA) is crucial for development, tissue homeostasis, vision, and immunity. Retinal, a form of VA, is produced via enzymatic cleavage of β-carotene by beta-carotene oxygenase 1 ( bco1 ) and bco1-like ( bco1l ). While bco1 is found across vertebrate taxa, bco1l is a paralog of bco1 that we discover to have evolved in the ray-finned fishes, the most abundant, speciose, and commercially important group of fishes. We investigated the function of bco1l in ray-finned Siamese fighting fish, commonly known as betta, an emerging model for genetics and development. Using CRISPR-Cas9 knockouts, we find that lack of bco1l results in reduced VA and elevated β-carotene in larvae, starting when animals have exhausted their yolk supply of retinal, followed by stunted growth and death during juvenile development. Exogenous retinoic acid rescues the mutation, demonstrating its deficiency causes these defects. bco1l is 4× more abundant than bco1 in the intestine. This, coupled with the inability of bco1 to sustain VA production in the bco1l mutant, indicates that bco1l is the primary enzyme for dietary carotenoid conversion into retinal. Our results show that VA production by bco1l is required for post-embryonic development, and that bco1l became essential after evolving via duplication of bco1 .

Population genomics elucidates the trajectory of chicken domestication from Asia to Japan

Poultry Science · 2025-03-18 · 5 citations

Chickens were domesticated over 4,000 years ago and are now the most popular poultry species in the world. In Japan, chickens are believed to have been first introduced around 2,000 years ago. Today, approximately 45 chicken breeds can be found in Japan, and they have unique and diverse phenotypic characteristics. However, their origins and histories have largely remained unexplored. Here, we newly sequenced whole genomes of 41 populations including 21 Japanese native chickens. By integrating them with published genomes to compile a total of 133 geographically comprehensive samples, we conducted population genomic analyses to elucidate the trajectory of their domestication from Asia to Japan. Our findings indicate that Japanese native chickens were derived from Southeast and East Asia, the centers of chicken domestication, through several separate events. The whole-genome phylogenetic analyses classified Japanese chickens into several groups and clarified the geographic origins of each group. These results provide new insights into the population structure, admixture history of Asian chicken breeds, and genomic trajectory of chickens from Asia to Japan.

Genetic Variation in Neurotransmitter Receptors Generates Behavioral Diversity

Digital Commons - RU (Rockefeller University) · 2025-09-08 · 1 citations

Variation in behavior among individuals is both remarkable and of great significance to society. People differ in locomotor skills, in sleep patterns, in their willingness to take risks, and in how they relate to other people. Whereas diversity enriches society, extreme behavioral deviations can be pathological, so it is important to identify the causes of behavioral variability. It is clear that both the environment and genetics contribute to behavioral diversity in all animals, but the nature of the specific genes involved is only beginning to emerge. The nematode worm Caenorhabditis elegans is a good animal model to study the genetic and neuronal bases of behavioral variation, as there are large differences in behavior between naturally-occurring strains, and powerful tools exist to characterize these differences. One example of the behavioral diversity of C. elegans is the existence of different thresholds for exploration—exploitation tradeoffs: some strains decide to exploit resources more thoroughly, while others decide to abandon resources earlier and explore other options. Using quantitative genetic tools I have found that genetic variation in the adrenergic receptor tyra-3 affects this exploration— exploitation decision. tyra-3 responds to the neurotransmitter tyramine, which is related to vertebrate adrenaline and noradrenaline. tyra-3 modifies the activity of sensory neurons that detect food cues and that regulate the decision to abandon depleting food resources. In strains that are more prone to exploration tyra-3 is expressed at lower levels, and this altered expression modifies the response of the sensory neurons to food. Variation in a gene that affects the response to the environment helps explain how nature and nurture interact to produce behavioral outcomes. In addition to variation in exploratory behavior, C. elegans strains also differ in social behaviors. In most strains animals aggregate with each other, whereas a few strains have evolved a solitary life-style. Variation in the neuropeptide Y receptor homologue npr-1 contributes to social behavior variation, but I found that other genes are also involved in this behavior. Through quantitative genetic analysis I identified polymorphisms in the GABA-gated cation channel exp-1 that generate variation in social behavior. Based on existing behavioral diversity in C. elegans, I discovered genetic variation in two neurotransmitter receptors and characterized the way in which this variation modifies the neuronal circuits that generate behavior. Consistent with findings in other systems, my results suggest that genetic variation in neurotransmitter receptors is a common way of generating behavioral diversity in animals.

Behavioral evolution by diverging cell type composition

Current Opinion in Genetics & Development · 2025-09-03 · 4 citations

Coordination and persistence of aggressive visual communication in Siamese fighting fish

bioRxiv (Cold Spring Harbor Laboratory) · 2024-05-01

ABSTRACT Animals coordinate their behavior with each other during both cooperative and agonistic social interactions. Such coordination often adopts the form of “turn taking”, in which the interactive partners alternate the performance of a behavior. Apart from acoustic communication, how turn taking between animals is coordinated is not well understood. Furthermore, the neural substrates that regulate persistence in engaging in social interactions are poorly studied. Here, we use Siamese fighting fish ( Betta splendens ), to study visually-driven turn-taking aggressive behavior. Using encounters with conspecifics and with animations, we characterize the dynamic visual features of an opponent and the behavioral sequences that drive turn taking. Through a brain-wide screen of neuronal activity during coordinated and persistent aggressive behavior, followed by targeted brain lesions, we find that the caudal portion of the dorsomedial telencephalon, an amygdala-like region, promotes persistent participation in aggressive interactions, yet is not necessary for coordination. Our work highlights how dynamic visual cues shape the rhythm of social interactions at multiple timescales, and points to the pallial amygdala as a region controlling engagement in such interactions. These results suggest an evolutionarily conserved role of the vertebrate pallial amygdala in regulating the persistence of emotional states.