Comparative Genomics of Non-Model Invertebrates

ESR Project 8: Ecdysozoa as a model system to test early animal evolution

Supervisor: Davide Pisani (University of Bristol), Co-supervisor Max Telford (UCL, London)

Student: Mattia Giacomelli

Objectives: The "Cambrian explosion" (~ 520 millions of year ago, MA) is the fossil signature of the radiation of bilaterally symmetrical animals (from worms to chordates). The history of Bilateria before the “explosion” is poorly understood, and molecular clocks suggest they are significantly older than the Cambrian (~650 MA). The discrepancy between rocks and clocks is often explained by claiming that early animals were microscopic (i.e. meiofaunal). Ecdysozoa (e.g. priapulid worms and arthropods) dominated the Cambrian, but while extant ecdysozoans include both microscopic and macroscopic species, it is unclear whether Precambrian ecdysozoans are unknown because they were microscopic or because they did not exist yet. Here we will use genomic information to test whether Ecdysozoa had a hidden Precambrian history.

O1: Sequence de novo genomes from unsampled and poorly sampled ecdysozoan phyla (Loricifera, Kinorhyncha, Priapulida, Tardigrada and Nematomorpha).

O2: Generate a new phylogenomic dataset, including multiple microscopic and macroscopic species across all ecdysozoan phyla by combining own data with public data.

O3: Identify signatures of secondary miniaturisation (e.g. lineage specific losses of regulatory elements) through comparative genomics.

O4: Understand ecdysozoan miniaturisation and test whether the last common ecdysozoan ancestor was meiofaunal.

Secondments: Max Telford (London), Yu Wang (Leibniz-Supercomputing Centre of the Bavarian Academy of Science and Humanities, Munich), Lyubomir Penev (Pensoft Publishers, Sofia).

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