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Reconstructing the Last Common Ancestor: Epistemological and Empirical Challenges
Amadeo Estrada1, Edna Suárez-Díaz2, Arturo Becerra3
1Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Coyoacán, Mexico.
Acta Biotheoretica
|May 16, 2022
Summary
Reconstructing the Last Common Ancestor (LCA) is challenged by Lateral Gene Transfer (LGT). A slim LCA, focusing on negative selection, and integrating organismal and geochemical data, offers a more achievable goal for understanding early life.
Area of Science:
- Evolutionary Biology
- Phylogenetics
- Astrobiology
Background:
- Molecular phylogenetics aims to reconstruct the Last Common Ancestor (LCA) and the Tree of Life (TOL).
- Lateral Gene Transfer (LGT) presents significant challenges to these reconstructions, leading to paradoxical results.
- Previous attempts at detailed LCA reconstruction face epistemic and empirical hurdles.
Purpose of the Study:
- To address the challenges posed by LGT in reconstructing the LCA.
- To propose an alternative approach for inferring the LCA's characteristics.
- To advocate for a more cautious and integrated perspective on early life evolution.
Main Methods:
- Analysis of molecular phylogenetic data, considering the impact of LGT.
- Focus on traits under strong Negative Natural Selection for LCA reconstruction.
- Integration of evidence from organismal biology and geochemistry.
Main Results:
- Detailed reconstruction of the LCA is deemed insurmountable due to LGT.
- A 'slim' LCA, based on conserved traits, is proposed as a viable alternative.
- The study highlights the limitations of solely relying on gene similarity statistics.
Conclusions:
- A middle-ground approach, reconstructing a slim LCA, is recommended.
- Consilience with organismal biology and geochemistry is crucial for robust inferences.
- Epistemic pluralism and evolving empirical data necessitate a cautionary perspective in studying early life.
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