macroevolution.abc – Abiota, Biota and Constraints in Macroevolutionary Processes

The Challenge

The phenotypic diversification of clades that manifest on geological time scales and the microevolutionary changes that take place on ecological time scales are processes that have defied linking.

Contradictory insights within and among fields of evolutionary biology highlight conceptual chasms: Why don’t we see more evolutionary change on macroevolutionary time scales, given high potential for trait evolution on shorter time scales? Why do ecological interactions observed in living communities exert large effects on organisms involved, yet are seldom found to have lasting effects on evolutionary outcomes on geological time scales?

A Solution

One reason why it has been difficult to resolve these contradictions is the lack of an empirical model system in which abiotic forces, biotic agents and evolutionary constraints can be integrated on different time scales.

macroevolution.abc aims to establish, de-novo, an empirical system that can stimulate newmodels to answer: To what degree does what happens on a generational time scale matter for diversification processes unfolding on a phylogenetic/geological time scale? How, exactly?

Cheilostome bryozoans as Drosophila of macroevolution

This project will develop and then consolidate cheilostome bryozoans as the Drosophila of macroevolution. Bryozoans are a uniquely ideal study system in which phenotypic (including life history), phylogenetic, environmental, direct biotic interaction data for extant and fossil populations can be collected in abundance.

Methodological Approaches

Our team combines paleontological field work, molecular sequencing of living bryozoans, collection of fossilized competitive interactions, extraction of phenotypic data, machine-learning and automation in data collection, and statistical modelling to understand the link(s) between macro- and microevolution.

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Fossilized biotic interactions. Top panel shows two different colonies of the cheilostome bryozoan species Antarctothoa tongima in a standoff interaction (open arrows), where neither colony wins. Bottom shows two different species (Micropora sp. on the left and Crepidacantha sp. on the right) in a reciprocal win-lose interaction (filled arrows are beside the zooids over growing the losing colony). Scale bars = 200 μm. SEMs by Dr E. Di Martino.

 
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An example of a molecular phylogeny we have generated for cheilostome bryozoans. Like many “minor” invertebrate groups, bryozoans have been largely neglected in next-generation molecular sequencing. By collaborating with many bryozoologists around the world, we have been accumulating tissue samples of diverse cheilostomes in order to infer phylogenetic histories independent of the phenotypes we want to study, and to alleviate the paucity of molecular data for our model group.
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Doing field work in 2017 in Wanganui, New Zealand. From left to right: Alan Beu, Kjetil L.Voje , Emanuela Di Martino, L. H. Liow, Carolann Schack, Seabourne Rust, Jeorne Boeve, Emily Enevoldesen. The cliffs behind us are fossiliferous. Photo taken by Paul D. Taylor.

 

Published Mar. 14, 2021 8:01 PM - Last modified Mar. 14, 2021 11:34 PM
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