The emergence and development of behavioral individuality in clonal fish

Behavioral individuality is a ubiquitous phenomenon in animal populations yet the origin and developmental trajectories of individuality, especially very early in life, are essentially still a black box. Using a high-resolution tracking system, we mapped the exact behavioral trajectories of genetically identical fish (Poecilia formosa), separated immediately after birth into identical environments, over the first 10 weeks of their life at 3 second resolution. We find that (i) strong behavioral individuality is present at the very first day after birth, (ii) behavioral differences at day 1 of life predict behavior up to at least 10 weeks later and (iii) patterns of individuality strengthen gradually over developmental time. Our results establish a powerful null model for how behavioral individuality can develop in the absence of genetic and environmental variation and provide experimental evidence that later-in-life individuality can be strongly shaped by factors pre-dating birth, like maternal provisioning, epigenetics and pre-birth developmental stochasticity.Funding provided by: Deutsche ForschungsgemeinschaftCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001659Award Number: BI 1828/2-1Funding provided by: Germany's Excellence Strategy*Crossref Funder Registry ID: Award Number: EXC 2002/1Funding provided by: Germany's Excellence Strategy*Crossref Funder Registry ID: Award Number: 390523135Funding provided by: Alexander von Humboldt-StiftungCrossref Funder Registry ID: http://dx.doi.org/10.13039/100005156Award Number: Postdoctoral FellowshipFunding provided by: Universität KonstanzCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100010583Award Number: Zukunftskolleg Institute of Advanced StudiesFunding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: IOS-210062