Many large nests are not only home to nest builders' young, but they also become spawning grounds for smaller species. If the bottom becomes silted up, for example because the mangrove forest is cut down, the fish face devastation.

Many nest-building fish spawn at the bottom. But what would happen if we do not take into account the fish's spawn? Reproduction must work – if you ignore it, we have no fish”, said Ola Svensson. “Sometimes you can hear people complain that 'we can't dredge right now, because the fish are spawning'. There is a tangible risk that people do great harm without understanding the consequences. Ola Svensson tells us that there are many species, even among aquarium fish and commercially important fish, whose reproduction and evolutionary ecology we don't know much about. The literature also shows large gaps in knowledge. Nest-building behaviour has evolved both as a result of natural selection and sexual selection.

The compilation provides a comprehensive overview of the knowledge that exists and that has been researched over the past 100 years. Ola Svensson doing field studies, together with research colleagues Charlotta Kvarnemo and Eva-Lotta Blom. We have also focused on definitions of nests, what they are, and definitions of sexual and natural selection”, said Ola Svensson, who declares that he learned a lot. We have noticed how research has changed, from a broader natural history view in the past with more peripheral information about what the fish are doing, to a narrower focus in modern research. “Research does not have to be new to be relevant and it does not have to have a quick impact or benefit. The article cites 200 of these, where they also draw parallels to other nest-building animals such as frogs and birds. Together with research colleague Charlotta Kvarnemo, Professor of Zoology at Gothenburg University, he has reviewed 400 books and articles focusing on sexual selection in nest-building fish. For almost 30 years now, he has been researching various parts of fish reproduction, and is the lead author of the article How sexual and natural selection interact and shape the evolution of nests and nesting behavior in fishes which has now been published in Philosophical Transactions of the Royal Society B: Biological Sciences.

Ola Svensson is Associate Professor in evolutionary ecology at the University of Borås, and mainly teaches biology to pre-school and teacher students.

Modern dredge