identifier: traitmech:000619
label: isogamy
definition: A sexual-reproduction phenotype in which the fusing gametes are similar
  in size.
definition_source: DOI:10.1038/s42003-022-04275-y
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1038/s42003-022-04275-y
  snippet: The gametes of isogamous species are of similar size and appearance.
  notes: Innami et al. (2022), PMID:36473948, PMC9726906. Exact Introduction Sec1
    sentence checked against raw Europe PMC XML and publisher HTML; not an abstract
    or web-summary quote. The paper identifies Chlamydomonas reinhardtii as isogamous
    while testing mating-structure positioning, not the maintenance of equal gamete
    size. Similar appearance does not exclude mating-type-specific structural or functional
    differences. Main text and captions were read; actual Figure 4 and Supplementary
    Table 2 were visually inspected. The latter lists nit1 nit2 in CC-125 and nit1
    nit2 agg1 in CC-124 despite their wild-type names. CC-3712 has a deletion including
    MID and lacks FUS1; CC-3947 carries a MID transgene. These are qualified laboratory
    observations, not unqualified natural exemplars. Other actual figures, supplementary
    figures and the source-data workbook remain uninspected. Phototactic fitness explanations
    in Discussion remain hypotheses, not measured consequences of isogamy.
- reference: DOI:10.1111/evo.13427
  snippet: we explored size-speed distributions in vegetative and gamete cells of
    10 cell lines, and clonal data from within two cell lines.
  notes: Seed and Tomkins (2018), PMID:29345308. Exact scientific-abstract clause
    from raw Europe PMC metadata; the author's institutional repository abstract corroborates
    the content. Its preceding clause identifies C. reinhardtii as isogamous. This
    independently supports experimental use of an isogamous microalga, not a second
    direct test of the definition's size-symmetry criterion. The two cell types are
    vegetative cells and gametes, not plus and minus gametes. Positive size-speed
    relationships and artificial speed selection do not establish a universal size
    threshold, identical gamete behaviour, or an evolutionary cause of isogamy. Full
    text, figures, supplements and strain provenance remain uninspected; the linked
    author manuscript returned HTTP 403.
discussions:
- discussion_id: isogamy-scope-and-hierarchy
  prompt: Keep gamete-size similarity distinct from mating-type identity.
  kind: CURATION_TODO
  status: OPEN
  rationale: This reproductive phenotype compares gametes participating in sexual
    fusion, not arbitrary equal-sized cells or vegetative-versus-gamete measurements.
    Similar size is not exact equality and does not imply identical structure, behaviour,
    recognition machinery or organelle inheritance. No numerical boundary with slight
    anisogamy is imposed. The fungal compatibility-locus systems traitmech:000615
    through traitmech:000618 and same-mating-type reproduction traitmech:000613 describe
    different axes; isogamy does not mean one mating type. Use released phenotype
    METPO:1000059 in record and proposal pending a narrower reproductive-phenotype
    hierarchy. PHYSIOLOGY is a filesystem category. Resolve exact lexical and external
    equivalences before adding synonyms or xrefs; no disjointness is asserted.
  posed_by: codex
  posed_date: '2026-10-05'
- discussion_id: isogamy-examples-and-mechanism
  prompt: Resolve natural strain provenance and mechanisms before extension.
  kind: CURATION_TODO
  status: OPEN
  rationale: The cited microalgal studies justify the trait, but collection provenance
    and unperturbed gamete measurements should be checked before adding a natural
    canonical example. A wild-type label alone does not establish that a reference
    strain lacks mutations. Do not turn MID-dependent mating-structure positioning
    into a demonstrated cause of gamete-size similarity. Resolve native protein accessions
    and experimentally tested size-control dependencies before a causal graph; no
    NONMECHANISTIC graph bypasses grounding. Read the remaining source material before
    quantitative or evolutionary extensions. Keep full-text quote checks distinct
    from abstract-resolver verdicts.
  posed_by: codex
  posed_date: '2026-10-05'
curation_history:
- timestamp: '2026-10-05T11:50:56Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added isogamy with two primary DOI-backed sources and exact full-text and
    scientific-abstract snippets. Kept gamete-size similarity distinct from structural
    symmetry, mating-type identity and sequence features. Ignored-and-hidden novelty
    and allocation searches found no exact record or collision. Reserved METPO:1057300
    in v496 under phenotype. Deferred natural canonical taxa, lexical mappings and
    causal graphs, with strain mutations and source-access limits explicit.
  llm_assisted: true