Gamete Dimorphism in Bryopsis plumosa Phototaxis, Gamete Motility and Pheromonal Attraction

Togashi, Tatsuya; Motomura, Taizo; Ichimura, Terunobu

doi:10.1515/botm.1998.41.1-6.257

Cited by 22 publications

(35 citation statements)

References 18 publications

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“…The evolutionary trajectory might not necessarily go to the direction with the highest fitness. In accordance with observations from nature, phenotypic variance in size of gametes produced within each mating type is constrained (20,21), and loci that determine gamete size are linked to loci that determine mating types (22,23). To keep the model as simple as possible, we use a haploid model that excludes the possibility of simultaneous (i.e., double) mutations in both sexes.…”

Section: Modelmentioning

confidence: 99%

“…Gametes are not generally spherical, but the spherical approximation is appropriate for gamete movement in a viscous medium at low Reynolds numbers (4). Gametes move in a random and uncorrelated fashion throughout the water at a speed inversely proportional to their radius because of Stokes law at low Reynolds numbers hydrodynamics (20,21). We use methods of collision kinetics similar to those methods used for hard sphere gases to calculate the number of collisions (details in ref.…”

Section: Model Specificationsmentioning

confidence: 99%

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Evolutionary trajectories explain the diversified evolution of isogamy and anisogamy in marine green algae

Togashi

Bartelt

Yoshimura

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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The evolution of anisogamy (the production of gametes of different size) is the first step in the establishment of sexual dimorphism, and it is a fundamental phenomenon underlying sexual selection. It is believed that anisogamy originated from isogamy (production of gametes of equal size), which is considered by most theorists to be the ancestral condition. Although nearly all plant and animal species are anisogamous, extant species of marine green algae exhibit a diversity of mating systems including both isogamy and anisogamy. Isogamy in marine green algae is of two forms: isogamy with extremely small gametes and isogamy with larger gametes. Based on disruptive selection for fertilization success and zygote survival (theory of Parker, Baker, and Smith), we explored how environmental changes can contribute to the evolution of such complex mating systems by analyzing the stochastic process in the invasion simulations of populations of differing gamete sizes. We find that both forms of isogamy can evolve from other isogamous ancestors through anisogamy. The resulting dimensionless analysis accounts for the evolutionary stability of all types of mating systems in marine green algae, even in the same environment. These results imply that evolutionary trajectories as well as the optimality of gametes/zygotes played an important role in the evolution of gamete size. convergent evolution | evolutionarily stable strategy | fertilization kinetics

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Section: Modelmentioning

confidence: 99%

Section: Model Specificationsmentioning

confidence: 99%

Evolutionary trajectories explain the diversified evolution of isogamy and anisogamy in marine green algae

Togashi

Bartelt

Yoshimura

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…Whether mucilage influences longevity is not known but, following dilution, motility of male gametes from brown and green algae has been reported for a variable (1-7 h) range of durations (e.g. Togashi et al 1998 ;Clifton and Clifton 1999 ; also reviewed in Brawley and Johnson 1992) and to be affected by salinity when marine taxa colonize brackish habitats (Serrão et al 1996a) . For marine invertebrates, sperm longevity varies widely.…”

Section: In Broadcast Spawnersmentioning

confidence: 99%

“…Havenhand 1991 ;Meidel and Yund 2001 ;Williams and Bentley 2002 ; also motile female gametes of green algae, Togashi et al 1998) . Again, the selective benefit of this trait seems questionable, since turbulence and advection might dilute gametes beyond the possibility of fertilization long before they become unviable (Levitan and Petersen 1995) .…”

Section: In Broadcast Spawnersmentioning

confidence: 99%

Fertilization Strategies

Serrão¹,

Havenhand²

2009

Ecological Studies

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“…The gametophytes of B. plumosa are usually dioecious and produce only gametes of a single gender. Dioecy can be seen in a strain collected from Muroran, Hokkaido Japan (Togashi et al 1998). In a dioecious strain of B. plumosa, it was shown that extracellular protoplasts obtained by removing cell walls from a gametophyte of one sex form new cell walls and develop into gametophytes of the same sex (Tatewaki and Nagata 1970).…”

Section: Introductionmentioning

confidence: 99%

Sexual fusion of protoplasts in a marine green alga, Bryopsis plumosa

et al. 2012

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We isolated protoplasts from male and female gametophytes of a strictly dioecious strain of the coenocytic marine green alga Bryopsis plumosa. The protoplasts successfully developed into macrothalli. These in turn produced swimming cells, which appeared similar to biflagellated gametes even when the mixed protoplasts were comprised of protoplasm from male and female gametophytes. We found that swimming cell sizes depended on the male/female protoplasm ratio; macrothalli successfully produced swimming cells with male/female protoplasm ratios of 10:0; 9:1; 7:3; 5:5; 1:9; and 0:10. In male/female protoplasm ratios ranging from equal to strongly female biased (5:5; 3:7; 1:9), swimming cells exhibited normal behaviors of gametes and resultant zygotes, displaying positive and negative phototaxis, respectively. Negatively phototactic swimming cells were quadriflagellated and had two nuclei, apparently as a result of fusion, but never developed into microthalli. Thus, these swimming cells might lack functionality essential for normal gametes. Our findings suggested that natural monoecy observed in this genus did not originate from hybridization of protoplasm between the sexes.

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Gamete Dimorphism in Bryopsis plumosa Phototaxis, Gamete Motility and Pheromonal Attraction

Cited by 22 publications

References 18 publications

Evolutionary trajectories explain the diversified evolution of isogamy and anisogamy in marine green algae

Evolutionary trajectories explain the diversified evolution of isogamy and anisogamy in marine green algae

Fertilization Strategies

Sexual fusion of protoplasts in a marine green alga, Bryopsis plumosa

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