quercusvirens, and also confirmed the matching of sexual and asexual generations
Other differences between budding in Botryllus and Perophora may also explain this discrepancy: in Botryllus, secondary buds develop simultaneously along with the two other asexual generations
(primary buds and zooids).
Some morphologists recognized a similarity between this zoospore-producing fruit, developing in situ upon a female thallus, and the spore-producing asexual generation of mosses.
Asexual generation A and sexual generation B followed the same growth-law and were thus homologous, whereas asexual generation C (the 'fruit') followed a different growth-law and was thus antithetic to A and B.
All colonies remained in the field through the beginning of the next asexual generation (hereafter termed takeover) and the full period of egg viability, so that eggs were fertilized by naturally available sperm.
Embryos at earlier developmental stages would have had insufficient time to complete development before the colony began a new asexual generation and the old zooids were resorbed (Stewart-Savage et al.
Takeover concludes with the cessation of heartbeat in zooids, and a new cycle begins with the opening of siphons in the next asexual generation
of zooids (panel A).
In this notation, "every one generation" corresponds to zero asexuality, "every three generations" corresponds to a pattern of two asexual generations
followed by one sexual generation, and so on.
Molecular parasites should thus be more successful in genomes that reproduce sexually than in those that replicate clonally (Hickey 1982), Chlamydomonas reinhardtii is a unicellular, heterothallic chlorophyte alga well suited to testing this prediction because it can be maintained with or without sex, and because its low doubling time permits the passage of hundreds of asexual generations
or dozens of sexual cycles per year (Harris 1989).