Seed weight and seed number affect subsequent fitness in outcrossing and selfing Primula species

Abstract

Using the outcrossing Primula farinosa and its autogamous selfing relatives P. scotica, P. scandinavica and P. stricta, we compared the fitness of light and heavy seeds. Heavy seeds germinated in greater numbers and more quickly. In competition with seedlings grown from lighter seeds, heavy seeds produced larger rosettes. In P. farinosa such seedlings went on to produce more seeds, and in two populations heavier seeds, than plants from lighter seeds. After transplantation to natural populations, seedlings of P. farinosa derived from heavy seeds produced larger rosettes, more flowers and seeds than those from lighter seeds in certain populations so that seedlings born of heavy seeds were much fitter than seedlings from lighter seeds. Average seed weight varied in inverse proportion to seed number per capsule. The autogamous species produced on average about twice as many seeds per capsule as P. farinosa. In P. scotica and P. stricta this difference appears to be due in part to assured fertilization, but this high fecundity did not cause disadvantageously light seeds. As these species produced fewer capsules per scape, their overall seed production was on average no greater than for P. farinosa. P. farinosa tradedoff fitness between capsules with large seed numbers, which donated more offspring to the next generation, and those with small seed numbers, whose heavy seeds would be more likely to reproduce themselves in the next generation. We conclude that low fecundity in outcrossing species might at times be advantageous.

Genetic and Physiological Architecture of Early Vigor in Aegilops tauschii, the D-Genome Donor of Hexaploid Wheat. A Quantitative Trait Loci Analysis

“…Seed size often correlates negatively with RGR (Van Rijn et al, 2000, and refs. therein), but there are also examples showing the opposite (Ló pezCastaneda et al, 1996;Treymayne and Richards, 2000;Van Rijn et al, 2000), or without correlation between seed mass and RGR (Clevering, 1999). We observed no correlation between seed mass and RGR 1 and a negative correlation between seed mass and RGR 2 (Table II).…”

How does the presence of endosperm affect seed size and germination?

“…percentage and germination time). The size of the endosperm also affects seed size and thus germination; large seeds have a higher probability of successful germination increasing the percentage and, in annuals, the incidence of early germination (Marshall, 1986;Triphati and Khan, 1990;Vera, 1997;Tremayne and Richards, 2000;Moles and Westoby, 2004). In this study, however, we did not fi nd a consistent pattern that would indicate that the presence of endosperm always translates into a higher percentage of germination or faster germination.…”

“…tion in seed size is common among and even within individual plants (Leishman et al, 2000) and a trade-off exists between producing small seeds with a higher probability of spatial and temporal escape (Leishman et al, 2000;Moles et al, 2005) and large vigorous seeds with higher success in germination, in terms of a higher percentage and/or speed of germination (Marshall, 1986;Triphati and Khan, 1990;Vera, 1997;Tremayne and Richards, 2000;Moles et al, 2000;Moles and Westoby, 2004), emergence and/or seedling growth (Leishman and Westoby, 1994;Osunkoya et al, 1994;Seiwa, 2000;Moles and Westoby, 2004).…”

The Importance of Ants and High-Shade Management to Coffee Pollination and Fruit Weight in Chiapas, Mexico

“…Higher fruit weights provide advantages to plants in terms of germination or seedling growth (Ngulube et al 1997;Eriksson 1999) or in other aspects of plant reproductive biology (Tremayne and Richards 2000;Mukasa and Ogata 2001;Schippers et al 2001). Furthermore, increased fruit weights confer obvious economic advantages to coffee farmers.…”