SCIENCE@home

Allometric Brain Development and Neuroecological Adaptations in Juvenile and Adult Raja polystigma

R. Porceddu,C. Porcu,S. Spiga,Jacopo Giuliani,Mara Carrus,G. Mulas,Blondine Agus,A. Bellodi,A. Mulas,M. C. Follesa

Published 2025 in Brain, Behavior and Evolution

ABSTRACT

Abstract Introduction: Chondrichthyans represent some of the earliest diverging lineages of jawed vertebrates, making them key models for studying the evolution of vertebrate brains. Despite their evolutionary significance, Mediterranean species remain understudied. This research focuses on the speckled skate (Raja polystigma), an endemic Mediterranean benthic species with distinct life history traits, such as bathymetric segregation and postnatal shifts in diet. These traits provide a unique opportunity to explore how ecological factors influence postnatal brain development and neuroecological adaptation in cartilaginous fishes. Methods: We examined the allometric relationship between brain mass and body mass in postnatal individuals of R. polystigma and assessed the relative growth of major brain regions, including the olfactory bulbs, telencephalon, diencephalon, optic tectum, cerebellum, and medulla oblongata. Data were analyzed using log-transformed linear regressions to determine differential growth rates and patterns of regional specialization during development. Results: Our analysis revealed that brain growth scales with negative allometry relative to body mass, indicating a slowdown in brain growth as individuals mature. Region-specific trends showed that the olfactory bulbs, cerebellum, and medulla oblongata grow at a faster rate than the rest of the brain, suggesting enhanced development of sensory and motor capacities. Conversely, the optic tectum exhibited slower growth, implying a reduced visual reliance in adults. The telencephalon and diencephalon scaled isometrically with brain mass, suggesting stable roles in cognitive and integrative functions throughout postnatal development. Conclusion: These findings highlight how ecological and behavioral shifts during development shape brain organization in R. polystigma. Enhanced growth of non-visual sensory regions and motor centers may reflect adaptations to a benthic lifestyle and bathymetric niche. This study contributes to our understanding of neuroecological evolution in Mediterranean chondrichthyans and underscores the value of R. polystigma as a model for investigating brain development in relation to ecological specialization. Plain Language Summary The speckled skate (R. polystigma) is a cartilaginous fish found only in the Mediterranean Sea. Understanding how its brain develops can help us learn how fish adapt to their environment. In this study, we examined how the brain of the speckled skate grows after birth and how different brain regions change in relation to body size. Our results show that as the skate grows, its brain increases in size more slowly than its body, which may be linked to reaching adulthood and sexual maturity. Some brain regions develop more rapidly than others, particularly those involved in smell (olfactory bulbs), movement (cerebellum), and the coordination of sensory and motor functions (medulla oblongata and cerebellar-like structures). The detection of water movements and electric field perception of other animals are processed in these latter brain areas. This suggests that, as the skate matures, all these sensory systems become more refined, improving movement control and environmental awareness. In contrast, the optic tectum, responsible for processing visual information, grows more slowly, indicating that adult skates may rely less on vision. Other regions, such as the telencephalon and diencephalon, grow at the same rate as the overall brain, suggesting stable cognitive and sensory functions throughout development. These findings provide new insights into how the speckled skate adapts to its environment, highlighting the role of sensory specialization during growth.

PUBLICATION RECORD

CITATION MAP

EXTRACTION MAP

CLAIMS

  • No claims are published for this paper.

CONCEPTS

  • No concepts are published for this paper.

REFERENCES

Showing 1-72 of 72 references · Page 1 of 1

CITED BY

  • No citing papers are available for this paper.

Showing 0-0 of 0 citing papers · Page 1 of 1