isogamy

traitmech:000619 · CLASS · PROPOSED

A sexual-reproduction phenotype in which the fusing gametes are similar in size.

Trait evidence (2)

DOI:10.1038/s42003-022-04275-y
The gametes of isogamous species are of similar size and appearance.

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.
DOI:10.1111/evo.13427
we explored size-speed distributions in vegetative and gamete cells of 10 cell lines, and clonal data from within two cell lines.

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.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1038/s42003-022-04275-y

Parent traits (1)

phenotype METPO:1000059

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Discussions and Knowledge Gaps (2)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Keep gamete-size similarity distinct from mating-type identity.

CURATION TODO OPEN isogamy-scope-and-hierarchy · raised by codex · 2026-10-05

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

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.

Resolve natural strain provenance and mechanisms before extension.

CURATION TODO OPEN isogamy-examples-and-mechanism · raised by codex · 2026-10-05

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

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.

Curation history

2026-10-05T11:50:56Z · MINTED_TRAITMECH_ID · codex
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.