Jonah Walker

In a little under 4 billion years, life has evolved from one primordial species into hundreds of millions of species. But the most striking feature of nature is the uneven distribution of species richness and phenotypic diversity across different lineages. In many groups of organisms, it takes close to a million years for one species to evolve into two species. In other groups, new species have evolved much faster. My work seeks to explain why some groups of organisms have evolved to become so diverse (with many species that all look very different) — while other groups have remained comparatively depauperate (with few species that look similar) in the same amount time.

Working between the Department of Zoology at the University of Cambridge and the Tree of Life Programme at the Sanger Institute, I am addressing two long-standing questions at the intersection of speciation genomics and sensory ecology. First, what role does hybridisation and genomic evolution play in fuelling bouts of rapid speciation and signal diversification? Second, how do signals evolve during the course of a radiation and what role do they play in facilitating speciation? I’m addressing these two questions by studying the peacock spiders of Australia specifically.

I firmly believe that biology benefits from an interdisciplinary and collaborative approach. Our research is grounded in field-based observation and we combine this with genomic sequencing, multispectral imaging, and behavioural experiments in the lab. Our research wouldn’t be possible without our many brilliant collaborators across the globe.

My research is kindly funded by the Herchel Smith Trust at the University of Cambridge and by the Wellcome Sanger Institute. I am supervised by Joana Meier and Chris Jiggins.

Peacock spiders

The peacock spiders of Australia represent a series of recent and rapid radiations. The genus Maratus comprises around 100 species and its males are infamous for the remarkable visual and vibrational dances that they perform to attract females. This extreme sexual dimorphism, together with a lack of observable ecological differentiation between closely-related species, suggests the radiation is driven partly by sexual selection. I am combining multispectral imaging, vibratory measurements, behavioural experiments, population genetics, and comparative genomics in my peacock spider work.

Our work on peacock spiders is done as part of an international collaboration spanning Australia, the UK, the US, Germany, and Austria. We work alongside a large network of local experts and taxonomists in Australia, without whom our work would not be possible. We study and collect spiders on the ancestral and unceded lands of many First Nations communities.

Additional projects

I’ve been very fortunate to work on a wide range of evolutionary projects. As part of the Integration of Speciation special topic network, I have been helping to develop an ontological classification for Reproductive Isolation in order to facilitate broad-scale comparisons of RI across diverse taxa. With Claire Spottiswoode, I have also studied the effect of interactions between brood parasitism and climate on egg signature evolution in Zambian Prinia warblers. And with Andrew Tanentzap, I investigated how predictable the evolutionary responses of Daphnia populations are to invasive predator introduction in Canadian lakes. I’ve also worked on stickleback collective behaviour, Heliconius signal evolution in Panama, and Podarcis lizard hybridisation in Switzerland.