Trade-off between vegetative regeneration and sexual reproduction of Sargassum thunbergii

Abstract

An ecological demographic study was conducted from January to December 2009 at Changshan Island on the northern side of Shandong Peninsula, China. The study investigated stem regeneration and the resource trade-off between sexual reproduction and vegetative regeneration of the brown alga Sargassum thunbergii at the individual thallus level. Stem regeneration from the holdfast occurred year round but with significant seasonality, peaking in the early summer. Both percentage of fertile stems and reproductive effort were negatively correlated with stem regeneration in the middle and later periods of sexual reproduction. Furthermore, the correlation coefficients increased significantly with time. These observations suggested that an increase in resource allocation to sexual reproduction would lead to a decrease in allocation to vegetative regeneration during the reproductive period. Reproductive effort was lower and stem regeneration was higher in the wave-exposed location compared with the sheltered location, indicating that allocation of resources between sexual reproduction and vegetative regeneration varied with location. When reproductive tissues were removed, the number of new stems produced from holdfasts increased, and when new stems were removed, an increase in reproductive effort occurred. These results suggest that trade-off between sexual reproduction and vegetative regeneration occurs in S. thunbergii.

Phenological study of Sargassum thunbergii (Fucales, Phaeophyta) in Lidao Bay, Rongcheng, China

“…thunbergii , consistent with prior studies (Umezaki, 1974;Koh et al, 1993;Zheng and Chen, 1993). The transition between the short and long length size classes suggests that there is a trade-off between sexual reproduction and vegetative regeneration, as noted by other authors (McCourt, 1984;Chu et al, 2011).…”

Seaweed reproductive biology: environmental and genetic controls

“…Åberg (1996) demonstrated differences in the annual reproductive effort of Ascophyllum nodosum between small and large individuals, which were interpreted as a reproductive trade-off by arguing that small individuals are better off investing in growth, which offers them a better chance of survival, while larger individuals can afford to invest in reproduction. By removing either vegetative stems or reproductive structures in Sargassum thunbergii, Chu et al (2011) demonstrated a trade-off between vegetative growth and reproduction. This study confirmed older observations by McCourt (1985) and Gillespie and Critchley (2001) of an inverse correlation between vegetative growth and reproductive effort among different Sargassum species in the Gulf of California and South Africa, respectively.…”

Evidence of reproductive cost in the triphasic life history of the red alga Gracilaria chilensis (Gracilariales, Rhodophyta)

“…receptacles and sporophylles) (Vernet and Harper 1980;McCourt 1985;Ang 1992;Mathieson and Guo 1992;Åberg 1996;Zou et al 2011). While a reproductive cost, like growth reduction or decrease of survival rate, has been observed in various fucoids (McCourt 1985;Ang 1992;Mathieson and Guo 1992;Åberg 1996;Chu et al 2011), the existence of resource trade-off in algae has been discussed, because reproductive organs are normally pigmented and potentially able to photosynthesis before the release of spores or gametes (De Wreede and Klinger 1990). However, the reproductive period coincide generally with the end of growth and can be followed by the senescence and the death of the parental thallus (Zou et al 2006).…”