Research - Marco Colnaghi

Selected Publications

Repeat sequences limit the effectiveness of LGT and favoured the evolution of meiotic sex in early eukaryotes

M Colnaghi, N Lane, A Pomiankowski – Under review

Early eukaryotes underwent an unprecedented expansion in genome size and complexity, a process that was accompanied by a sharp rise in genetic repeats density. Using theoretical models, I demonstrate that these factors severely limit lateral gene transfer’s ability to prevent Muller’s ratchet, creating the conditions for the evolution of meiotic sex.

The need for high-quality oocyte mitochondria at high ploidy dictates mammalian germline development

M Colnaghi, A Pomiankowski, N Lane – Elife, 2021

How do germline processes help maintain mitochondrial quality in the face of mutation accumulation? Using computational and evolutionary models, I study the interplay between different levels of selection (individual, cell, and organelle) and show the importance of organelle-level selection in achieving high-quality mitochondria at extreme ploidy in mature oocytes. These findings explain the major features of female germline architecture, notably the longstanding paradox of over-proliferation of primordial germ cells followed by massive loss.

Genome expansion in early eukaryotes drove the transition from lateral gene transfer to meiotic sex

M Colnaghi, N Lane, A Pomiankowski – Elife, 2020

In prokaryotes, recombination of environmental DNA through Lateral Gene Transfer (LGT) can prevent the accumulation of deleterious mutations. Why did the first eukaryotes abandon LGT in favour of sexual reproduction? The greater complexity of eukaryotes is linked with larger genomes; I demonstrate that the benefit of LGT declines rapidly with genome size, and the degeneration of larger genomes can only be resisted by increases in recombination length, to the same order as genome size – as occurs in meiosis. These results elucidate the strong selective pressure towards the evolution of meiotic sex.