Discrimination, crypticity, and incipient taxa in entamoeba

Area of Science:

• Microbiology
• Evolutionary Biology
• Protistology

Background:

• The classical species concept faces challenges in resolving lineages in diverging prokaryotic and unicellular eukaryotic populations.
• Current phylogenetic studies often rely on single-gene or morphological traits, obscuring natural lineages referred to as "cryptic."
• Kin discrimination behavior, observed in social microbes, offers a potential avenue for resolving cryptic varieties in non-social protists.

Purpose of the Study:

• To investigate the potential of aggregative behavior in a non-social protist, Entamoeba invadens, for defining cryptic phylogenetic varieties.
• To determine if two specific strains of Entamoeba invadens (IP-1 and VK-1:NS), considered closely related, exhibit kin discrimination.

Main Methods:

• Behavioral and chemical analyses of interactions between trophozoites of two Entamoeba invadens strains (IP-1 and VK-1:NS).
• Observation of aggregative behavior and discrimination patterns when strains were mixed.

Main Results:

• Entamoeba invadens strains IP-1 and VK-1:NS trophozoites demonstrated strain-specific aggregation, interacting only with members of their own strain.
• Evidence of discrimination between different strains was observed, mediated by distinct behavioral and chemical signals.

Conclusions:

• Kin discrimination based on chemical and behavioral signals plays a role in lineage resolution within Entamoeba populations.
• Integrated approaches combining morphological, behavioral/chemical, and ecological data are crucial for improving Archamoebae phylogenies and defining cryptic varieties.
• The observed evolutionary processes, driven by selection, provide a natural explanation for the emergence of new lineages and protistan diversity, refuting creationist viewpoints.