Possibility that individuality exists in animal behavior from 'first day after birth'

Individuality exists in the behavior of animals, including humans, but there are many unclear points about when the individuality of behavior occurs and develops. Therefore, when we conducted an experiment that followed the behavior of genetically identical cloned fish immediately after birth, we found that behavioral individuality exists from the ``first day after birth''.

The emergence and development of behavioral individuality in clonal fish | Nature Communications


In general, behavioral individuality is thought to arise based on differences in conditions such as genes and social environments. However, in a 2017 study using the Amazon molly , which is known to reproduce asexually, individuals with the same genes were bred in a highly standardized environment, but behavioral individuality was observed at 7 weeks of age. Reported confirmed.

The following is a simple diagram showing three patterns that show individuality. The left is ``pattern in which individuality exists at birth'', the middle is ``pattern in which individuality gradually appears after birth'', and the right is ``pattern in which individuality suddenly appears at a specific point''.

Therefore, a research team at the

Leibniz Institute for Freshwater Ecology and Inland Water Fisheries separated genetically identical Amazon mollies into the same environment immediately after birth and conducted an experiment to track their behavior using a high-performance tracking system. rice field.

In the experiment, freshly born fish with the same genes were housed in tanks with identical environments such as light and temperature conditions, food, and social density. Then, using an automated recording system built with a Raspberry Pi single-board computer and a camera, the fish were photographed regularly from immediately after containment until they were 10 weeks old. Below is a picture of an Amazon Molly.

Photographs were taken every 3 seconds during the 11 hours during the day when the fish were active, and the number of photographs taken per day was 13,200, and the total number of images taken during the experiment was one per fish. It is reported to have sold over 900,000 copies. The image data was converted into a time-lapse movie every day, the position coordinates in the tank were extracted with custom tracking software, and the individuality of behavior such as the median swimming speed and activity tendency was tracked.

As a result of the experiment, it was confirmed that the behavioral personality of Amazon Morley was consistently present from the first day after birth, and that the difference in personality could not be explained by the mother or body size. The research team also reports that individuality was gradually strengthened until the 10th week of life, and that individuality in early development has a significant and strong positive correlation with individuality in late development.

The graph below shows how the swimming speed of a specific solid inferred from the data changed over time. Individuals that were fast swimmers immediately after birth became even faster in later stages, while those that were slow remained slow, showing a tendency to maintain and strengthen individuality in the early stage of development.

Regarding the fact that individuality differences occur immediately after birth in genetically identical individuals, the research team hypothesized that `` differences in the maternal environment such as maternal DNA methylation and hormones '' and `` molecular, neurological, physiological As a result of the stochastic variation of the marker'. In any case, individual differences arising from these differences may increase adaptability as a species to the environment and increase the survival probability of genetically identical Amazon molly.

'Behavioral individuality is a fundamental characteristic of animal populations. Our study explores how these inter-individual differences change and develop in the absence of genetic and environmental differences.' 'Individuality is generally thought to arise from genes, differences in experience, and specific ecological conditions. However, our study suggests that more subtle processes before birth suggest that it may play a fundamental role in generating behavioral individuality: individuals are innately unique, but that does not negate behavioral change over a lifetime. That's it,' he said.

in Science,   Creature, Posted by log1h_ik