Biology subjects

Kohda, M.

Publications and source records attributed to Kohda, M..

5 recordsLinked to original sources

bioRxiv2024

Three-spined sticklebacks recognise familiar individuals by facial recognition

Social vertebrates often recognise familiar individuals by facial recognition, a basal cognitive ability by which animals establish stable sociality, including territoriality. The three-spined stickleback (Gasterosteus aculeatus), a model species for behavioural studies, is territorial; its ability to visually recognise familiar individuals remains unclear. Here, we report that this species has individual-specific facial colour morph features and can recognise familiar individuals by facial recognition. Territorial neighbours of the same sex established a "dear enemy relationship" with each other. These focal fish were exposed to composite photographic models of four combinations of faces and bodies of familiar neighbours and unknown strangers of the same sex. Focal fish of both sexes frequently attacked photographs of strangers (stranger-face/stranger-body) more frequently than familiar neighbours (neighbour-face/neighbour-body). Furthermore, they attacked composite photographs of stranger-face/neighbour-body more frequently (similar to the stranger model) but less frequently attacked photographs of neighbour-face/stranger-body (similar to the neighbour model). These results suggest that the three-spined stickleback distinguishes familiar neighbours from unknown fish exclusively via facial recognition. The aggressiveness of males was independent of the presence of red nuptial colour on photograph-models. Our findings suggest that this fish controls its aggressiveness against opponent conspecifics in the context of social relationships independent of the sign-stimulus.

animal behavior and cognition↗

bioRxiv2024

Facial Coloration as a Social Signal in a Neotropical Cichlid: Testing the Facial Expression Hypothesis

The face is a uniquely distinctive stimulus, encapsulating a wealth of information. Among the myriad of social cues conveyed by the face, emotional signals, known as facial expressions, are paramount not only for humans but also for numerous social animals. The evolution of facial expressions in these animals can also manifest in taxa other than mammals, as suggested by various studies highlighting the socio-ecological benefits of facial expressions. In this study, we elucidated the social function of facial coloration, determined by melanophores, in the neotropical social cichlid Symphysodon aequifasciatus. In this species, facial coloration exhibits instantaneous changes in response to varying social contexts. Through behavioral observations and experimental manipulation, we confirmed that facial coloration in S. aequifasciatus serves to attenuate unnecessary aggressive competition among conspecifics. Furthermore, we observed that the facial area subjected to coloration in this species is innervated by the adenosine triphosphate- and noradrenaline-ergic nervous system. These findings indicated that facial expression in S. aequifasciatus depends on the sympathetic nervous system and has evolved independently of mammalian facial expressions. Our study highlights teleost fishes as valuable animal models for exploring the universality of facial expressions and their underlying cognitive mechanisms in vertebrates.

animal behavior and cognition↗

bioRxiv2024

The influence of sleep disruption on learning and memory in fish

Sleep is ubiquitous across animal taxa. Strong evolutionary pressures have conserved sleep over the evolutionary history of animals, yet our understanding of the functions of sleep still largely derives from mammals and select laboratory models. Sleep is considered to play an important role in mental processes, including learning and memory consolidation, but how widespread this relationship occurs across taxa remains unclear. Here, we test the impact of sleep disruption on the ability of the cleaner fish (Labroides dimidiatus) to both learn and then remember a novel cognitive task. We found a significant negative relationship between sleep disruption and the ability to learn a food reward choice system. Specifically, we found that fish in a disturbed sleep treatment took significantly longer and made more incorrect decisions when finding the food reward, compared to individuals in a non-disturbed/normal sleep treatment. In contrast, the differences between the two treatment groups were non-significant when fish where tasked with remembering the food reward several days later. Our results demonstrate a negative impact of sleep disruption on performance in a cognitive challenging task and that the effects were strongest when fish were first exposed to the challenge. Importantly, we show that the association between sleep and mental processes, such as learning, may be widespread across vertebrate taxa and potentially have an early origin in the evolutionary history of animals.

animal behavior and cognition↗

bioRxiv2023

Sperm competition influences sperm quality and seminal plasma protein expression among territorial males of the courtship cichlid

Sperm competition drives the plasticity of sperm quality and seminal fluid. However, how environmental and behavioral factors influence sperm competition and its outcome on the plasticity of sperm quality are unknown. In this study, we show males can asses the sperm competition level, and their fertilization-promoting sperm traits changes according to intensity. The promiscuous Tanganyikan cichlids Ophthalmotilapia ventralis perform their fertilization in the female mouth cavity. Sperm competition occurs in the female mouth as sperm is collected from multiple males. Behavioral (i.e., courtship success rates [CSR]) and environmental (density of spawning sites [DS]) factors are related to sperm collection. Seminal plasma glycoprotein 120 (SPP120) aids in sperm immobilization and aggregation, and sperm quality (longevity and velocity) could increase the probability of siring offspring. Based on an assumption of the involvement of DS and CSR on sperm collection, DS and CSR could influence the expression of SPP120 and sperm quality. We examined how sperm quality and SPP120 affect sperm competition-associated CSR and DS. Sperm longevity and velocity were positively correlated with DS. SPP120 expression was also positively correlated with CSR and DS. The plasticity of sperm quality and amount of SPP120 result in high fertilization competency according to sperm competition level.

evolutionary biology↗

bioRxiv2018

Cleaner wrasse pass the mark test. What are the implications for consciousness and self-awareness testing in animals?

The ability to perceive and recognise a reflected mirror image as self (mirror self-recognition, MSR) is considered a hallmark of cognition across species. Although MSR has been reported in mammals and birds, it is not known to occur in any other major taxon. A factor potentially limiting the ability to test for MSR is that the established assay for MSR, the mark test, shows an interpretation bias towards animals with the dexterity (or limbs) required to touch a mark. Here, we show that the cleaner wrasse fish, Labroides dimidiatus, passes through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror (contingency testing), and (iii) frequent observation of their reflection. When subsequently provided with a coloured tag, individuals attempt to remove the mark in the presence of a mirror but show no response towards transparent marks, or to coloured marks in the absence of a mirror. This remarkable finding presents a challenge to our interpretation of the mark test - do we accept that these behavioural responses in the mark test, which are taken as evidence of self-recognition in other species, mean that fish are self-aware? Or do we conclude that these behavioural patterns have a basis in a cognitive process other than self-recognition? If the former, what does this mean for our understanding of animal intelligence? If the latter, what does this mean for our application and interpretation of the mark test as a metric for animal cognitive abilities?

animal behavior and cognition↗