Agmatoploidy and symploidy: a critical review

Area of Science:

• Cytogenetics
• Evolutionary Biology
• Genomics

Background:

• Agmatoploidy is a proposed mechanism for chromosome number doubling via fragmentation.
• It is theorized to be significant in karyotype evolution, particularly in species with holokinetic chromosomes.
• Related concepts include symploidy, partial agmatoploidy, and polyagmatoploidy.

Purpose of the Study:

• To critically review the literature on agmatoploidy and related karyotype changes.
• To evaluate the evidence and definitions of these chromosomal rearrangement terms.
• To propose a revision or abolition of certain terminology in karyotype evolution.

Main Methods:

• Literature review and critical analysis of existing studies on chromosome rearrangements.
• Comparison of definitions and proposed mechanisms for agmatoploidy, symploidy, and disploidy.
• Evaluation of evidence supporting chromosome number doubling via agmatoploidy.

Main Results:

• Evidence for agmatoploidy leading to complete chromosome number doubling is scarce and not well-demonstrated.
• Partial agmatoploidy and partial symploidy appear to be synonymous with ascending and descending disploidy, respectively.
• The proposed terms lack clear distinction and empirical support.

Conclusions:

• Agmatoploidy as a distinct mechanism for doubling chromosome number is poorly supported.
• The terms partial agmatoploidy and partial symploidy are likely redundant with existing disploidy concepts.
• It is recommended to avoid or abolish these terms to improve clarity in karyotype evolution research.