A hierarchical view of convergent evolution in microbial eukaryotes

Area of Science:

• Evolutionary Biology
• Microbial Ecology
• Phylogenetics

Background:

• Distinguishing convergent evolution is vital for understanding evolutionary relationships and natural selection.
• Convergent evolution in microbial eukaryotes is pervasive but underexplored compared to animals and plants.
• Microbial convergence differs from that in multicellular organisms due to large phylogenetic distances and limited morphological repertoires.

Purpose of the Study:

• To systematically explore and articulate the pervasiveness and adaptive significance of convergent evolution in microbial eukaryotes.
• To propose a hierarchical framework for understanding phenotypic convergence.
• To provide compelling examples of microbial convergence and suggest future research directions.

Main Methods:

• Categorization of phenotypic convergence into three types: parallel, proximate, and ultimate.
• Analysis of microbial eukaryotes across diverse environments (planktonic, interstitial, host-associated).
• Review and synthesis of existing literature on microbial convergent evolution.

Main Results:

• Three overlapping categories of phenotypic convergence are proposed: subcellular analogues, analogues between cellular and multicellular systems, and multicellular analogues.
• Microbial eukaryotes in planktonic, interstitial, and host-associated environments exemplify 'ultimate convergence'.
• Convergence at different phylogenetic levels provides distinct insights into macroevolutionary processes.

Conclusions:

• Convergent evolution in microbes offers unique perspectives on macroevolutionary diversification.
• A hierarchical classification of convergence is essential for a comprehensive understanding of life's history.
• Further research is needed to fully elucidate the structure of convergent evolution in microbial lineages.