Alfonso M Sánchez-Lafuente1, Raquel Parra. 1. Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 9, 41012 Sevilla, Spain. slafuente@us.es
Abstract
BACKGROUND AND AIMS: The phenotypic selection of a diverse insect assemblage was studied on a generalist plant species (Paeonia broteroi) in ten flowering seasons, with tests for whether visitor preferences for plants with larger flowers eventually translated into significant differences among plants in visitation rates, seed production, seed mass, seed germination and seedling survival. METHODS: Selection gradients were used to assess if selection on flower size contributed to explain differences in visitation rates, seed production and seed mass. First, independent analyses were carried out for each season; then for the ten season as a whole. Seedling emergence and survival were assessed by generalized linear models. KEY RESULTS: Directional selection was found on flower size through visitation rates and seed production, and stabilizing selection through seed mass. Thus, larger flowers were more visited, and produced more, but lighter seeds, than smaller flowers. The results suggest a conflicting selection on flower size through seed number and size. Floral integration found in the study populations was larger than that in populations of a distant region. Finally, seed size did not influence seedling emergence and survival; thus, any advantages of seed size may be constrained under natural conditions before plants become reproductive individuals. CONCLUSIONS: Plants with larger flowers may be benefited by producing more lighter seeds than fewer heavier ones, as they may contribute disproportionately to the seed bank, and have better chances that any descendant could eventually recruit. However, it seems unlikely that differences in flower size and integration found among populations in different regions could have been originated by rapid evolutionary change. First, because of the conflicting selection described; second, because of the remarkably low seedling survival found under natural conditions. Consequently, the influence of pollinator selection alone does not seem to explain differences in flower size and integration.
BACKGROUND AND AIMS: The phenotypic selection of a diverse insect assemblage was studied on a generalist plant species (Paeonia broteroi) in ten flowering seasons, with tests for whether visitor preferences for plants with larger flowers eventually translated into significant differences among plants in visitation rates, seed production, seed mass, seed germination and seedling survival. METHODS: Selection gradients were used to assess if selection on flower size contributed to explain differences in visitation rates, seed production and seed mass. First, independent analyses were carried out for each season; then for the ten season as a whole. Seedling emergence and survival were assessed by generalized linear models. KEY RESULTS: Directional selection was found on flower size through visitation rates and seed production, and stabilizing selection through seed mass. Thus, larger flowers were more visited, and produced more, but lighter seeds, than smaller flowers. The results suggest a conflicting selection on flower size through seed number and size. Floral integration found in the study populations was larger than that in populations of a distant region. Finally, seed size did not influence seedling emergence and survival; thus, any advantages of seed size may be constrained under natural conditions before plants become reproductive individuals. CONCLUSIONS: Plants with larger flowers may be benefited by producing more lighter seeds than fewer heavier ones, as they may contribute disproportionately to the seed bank, and have better chances that any descendant could eventually recruit. However, it seems unlikely that differences in flower size and integration found among populations in different regions could have been originated by rapid evolutionary change. First, because of the conflicting selection described; second, because of the remarkably low seedling survival found under natural conditions. Consequently, the influence of pollinator selection alone does not seem to explain differences in flower size and integration.
Authors: H E Hoekstra; J M Hoekstra; D Berrigan; S N Vignieri; A Hoang; C E Hill; P Beerli; J G Kingsolver Journal: Proc Natl Acad Sci U S A Date: 2001-07-24 Impact factor: 11.205
Authors: Alfonso M Sánchez-Lafuente; Javier Guitián; Mónica Medrano; Carlos M Herrera; Pedro J Rey; Xim Cerdá Journal: Ann Bot Date: 2005-08-10 Impact factor: 4.357
Authors: P J Rey; C M Herrera; J Guitián; X Cerdá; A M Sánchez-Lafuente; M Medrano; J L Garrido Journal: J Evol Biol Date: 2006-01 Impact factor: 2.411
Authors: Keliang Zhang; Linjun Yao; Yin Zhang; Jerry M Baskin; Carol C Baskin; Zuoming Xiong; Jun Tao Journal: Planta Date: 2018-10-01 Impact factor: 4.116