Brain size evolution in pipefishes and seahorses: the role of feeding ecology, life history and sexual selection

Tsuboi, Masahito; Lim, Adam Chee Ooi; Ooi, Boon Leong; Yip, Mei Yee; Chong, Ving Ching; Ahnesjö, Ingrid; Kolm, Niclas

doi:10.1111/jeb.12995

Cited by 10 publications

(11 citation statements)

References 85 publications

(150 reference statements)

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“…An interspecific analysis of trophic ecology in syngnathid fishes is consistent with this hypothesis, and indicates that long-snouted species consume significantly more mobile and smaller prey than do species with short snouts (Kendrick and Hyndes 2005). Increases in snout to head length ratios have also been associated with increases in brain size in this group, a relationship that may reflect the importance of enhanced visual information processing when feeding on highly mobile prey (Tsuboi et al 2017).…”

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confidence: 60%

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The evolution of ecological specialization across the range of a broadly distributed marine species

et al. 2020

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Ecological specialization is an important engine of evolutionary change and adaptive radiation, but empirical evidence of local adaptation in marine environments is rare, a pattern that has been attributed to the high dispersal ability of marine taxa and limited geographic barriers to gene flow. The broad‐nosed pipefish, Syngnathus typhle, is one of the most broadly distributed syngnathid species and shows pronounced variation in cranial morphology across its range, a factor that may contribute to its success in colonizing new environments. We quantified variation in cranial morphology across the species range using geometric morphometrics, and tested for evidence of trophic specialization by comparing individual‐level dietary composition with the community of prey available at each site. Although the diets of juvenile pipefish from each site were qualitatively similar, ontogenetic shifts in dietary composition resulted in adult populations with distinctive diets consistent with their divergent cranial morphology. Morphological differences found in nature are maintained under common garden conditions, indicating that trophic specialization in S. typhle is a heritable trait subject to selection. Our data highlight the potential for ecological specialization in response to spatially variable selection pressures in broadly distributed marine species.

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supporting

confidence: 60%

“…Increases in snout to head length ratios have also been associated with increases in brain size in this group, a relationship that may reflect the importance of enhanced visual information processing when feeding on highly mobile prey (Tsuboi et al. ).…”

mentioning

confidence: 89%

The evolution of ecological specialization across the range of a broadly distributed marine species

et al. 2020

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“…The nervous system was completely formed in H. guttulatus newborns, with a progressive increase in size of the optic tectum and differentiation of pituitary gland and saccus vasculosus. A recent study on the evolution of the brain in Sygnathidae (Tsuboi et al ., ) supports the hypothesis that brain development is based on evolutionary capabilities adapted to feeding on highly mobile prey, so that the processing of visual information led to larger brain sizes compared with species that feed on less mobile prey (Tsuboi et al ., ). Environmental adaptation also contributes to modifications in the brain structure, resulting in increased eye size in planktivorous fish and an enlargement of the optic tectum in species feeding on fast‐moving prey (Kotrschal et al ., ).…”

Section: Discussionmentioning

confidence: 99%

Histological development of the long‐snouted seahorse Hippocampus guttulatus during ontogeny

Ofelio

Díaz

Radaelli

et al. 2018

Journal of Fish Biology

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The objective of the present study was to describe histological development of the European long-snouted seahorse Hippocampus guttulatus, to increase understanding of the biology and physiology of the species. Most vital organs were present in juveniles by the time of their release from the male's pouch. Digestive tract specialization occurred at 89 effective day-degrees (D° ), corresponding to 15 days post partum (dpp), with development of the first intestinal loop and mucosal folding. At 118 D° (20 dpp), lipids were being mobilized from the liver and oocytes attained the perinuclear stage. The fovea emerged at 177 D° (30 dpp), contemporaneous with the shift from pelagic to benthic behaviour in juveniles. At this stage, the most interesting feature was the formation of the second intestinal loop. Male gonads were never observed during the study (from 0 to 354 D° ; 0-60 dpp), but the first oogonia were present at 30 D° (5 dpp). In 354 D° (60 dpp) juveniles, oocytes were observed in a cortical alveoli stage, indicating maturity. Low digestive efficiency was observed at early stages, which was due to a poorly developed gastrointestinal tract and an immature digestive tract prior to 89 D° . The present study demonstrates that approximately 89 and 177 D° represent two important transitional stages in the early development of H. guttulatus. At a temperature of approximately 19 ± 1°C and an age of 1 month (177 D° ), main organs were fully functional, suggesting that the adult phenotype was largely established by that age, with females becoming mature at the age of 2 months (354 D° ).

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“…Studies in the field of evolutionary neuroscience have shown that the physiological and reproductive behaviors of a species are reflected in the structure of the CNS (Kotrschal et al 1998, Gonzalez-Voyer et al 2016, Tsuboi et al 2017. We show that the brain of H. barbouri contains a large optic tectum, whereas the size of the cerebellum is not abnormal.…”

Section: Discussionmentioning

confidence: 48%

“…Although no information is available on the feeding ecology of this species during the first month of development, our finding probably reflects the structurally complex habitat where H. barbouri catches prey. This may be a unique characteristic for syngnathid fish since they commonly have the longest snout and consume highly mobile prey, such as mysids, shrimps and fish (Kotrschal et al 1998, Kendrick and Hyndes 2005, Garamszegi et al 2005, de Lussanet and Muller 2007, Van Wassenbergh et al 2011, MacLean et al 2014, Lefebvre et al 2016, Tsuboi et al 2017.…”

Section: Discussionmentioning

confidence: 99%

The microanatomy of the central nervous system and brain of the Indo-Pacific seahorse, Hippocampus barbouri, during development

Senarat¹,

Kettratad²,

Kaneko³

et al. 2020

Zoologia

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The central nervous system (CNS) of Teleostei is a complex system of self-governance and its morphology is reflected in the physiological and reproductive behaviors. The Indo-Pacific seahorse, Hippocampus barbouri Jordan & Richardson, 1908, is a new candidate species for aquaculture in Thailand. In this study, we investigated the brain morphology of H. barbouri across various developmental windows. Light microscopic observations of adult brains revealed a large optic tectum in the mesencephalon, whereas the cerebral hemispheres and the cerebellum are of medium size. The detailed brain structures were generally similar to those of other teleosts; however, only five distinct layers were present in the optic tectum, including the stratum marginale, stratum opticum, stratum album central, stratum griseum central, and stratum periventriculae, versus six layers observed in other fish. One day after birth (1 DAB) the brain was a packed structure without any clear sub-structures. The number of capillaries in the optic tectum began to increase at 6 DAB, and at 14 DAB several features, including small blood vessels in the optic tectum and Purkinje cells, became noticeable. By 35 DAB, the optic tectum became highly vascularized and included five layers. Additionally, large Purkinje cells were developed in the cerebellum. Based on the brain development pattern, we speculate that the predatory ability of this fish starts to develop from 6 to 14 days after birth.

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Brain size evolution in pipefishes and seahorses: the role of feeding ecology, life history and sexual selection

Cited by 10 publications

References 85 publications

The evolution of ecological specialization across the range of a broadly distributed marine species

The evolution of ecological specialization across the range of a broadly distributed marine species

Histological development of the long‐snouted seahorse Hippocampus guttulatus during ontogeny

The microanatomy of the central nervous system and brain of the Indo-Pacific seahorse, Hippocampus barbouri, during development

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