Differences in life history traits of relatedEpilobium species: Clonality, seed size and seed number

Abstract

Small changes in morphology can affect the performance and functions of organisms and hence their ecological success. In modular constructed plants, contrasting growth strategies may be realized by differences in the spatial arrangement and size of shoots. Such differences change the way in which meristems and resources are assigned to various functions during the lifespan of a plant. If such changes include the capacity to spread clonally, sexual reproduction may also be affected. I compare patterns in vegetative growth and sexual reproductive traits in four allopatric species of Epilobium which are sometimes considered as subspecies of a single polymorphic taxon. The four species differ in the location of the buds which annually renew the aerial shoot system. E. dodonaei and E. steveni do not spread clonally and are characterized by a shrub-like habit. E. fleischeri, a species occurring only in the Alps, and E. colchicum, which occurs in the upper region of the Caucasus mountains, both produce buds on horizontal roots or plagiotropic shoots. Both alpine species exhibiting clonal growth have smaller shoots, fewer fruits and smaller seeds than the lowland species. An intraspecific trade-off between seed number per fruit and seed mass is realized. Both alpine species produce more seeds per fruit at the expense of seed mass. The morphological relationship between the four species and their geographical distribution suggest that clonal growth in E. fleischeri (restricted to the Alps) and E. colchicum (restricted to the Caucasus) is adaptively associated with the stressful conditions of alpine habitats. Our results suggest that clonal growth is not necessarily correlated with reduced reproduction by seeds. The success of plants which are already established may largely depend on clonal spread, but the colonization of new habitats depends on the production of a large number of small seeds with high dispersability.

Altitudinal changes in the growth and allometry of Rumex alpinus

“…Similarly, the investment in clonal reproduction of Geum reptans was greater at the highest locations on an altitudinal gradient rather than at middle altitudes, where the species was most abundant ). Harsh climatic conditions are reported to be a main reason why clonal plants invest more in clonal growth than in flowering at high altitudes (Billings and Mooney 1968;Bliss 1971;Douglas 1981;Stöcklin 1999;Stöcklin et al 2009;Pellissier et al 2010; but see Milla et al 2009). For R. alpinus, the negative correlation between flowering and altitude might be explained by supraoptimal conditions for formation of the flowering meristem in autumn or early spring (unpublished results).…”

Long-term Population Development and Spatial Pattern of Carex curvula Subspecies

“…If k remains more than 1.0, it may be assumed that the population size can be steadily maintained by clonal reproduction (Shimizu et al, 1998). Clonality has already been recognized as one of the essential features of plants growing under harsh arctic and alpine conditions (Callaghan, 1988;Stöcklin, 1999).…”

Adaptive genetic differentiation in life-history traits between populations of Mimulus guttatus with annual and perennial life-cycles

“…The balance between both modes of reproduction is one of the most important life-history characteristics of plants due to its effects on demography (Abrahamson 1980;Eriksson 1986), population genetic structure (McLellan et al 1997;Chung and Epperson 1999;Ceplitis 2001), dispersal (Stö cklin 1999;Winkler and Fischer 2001) and meta-population processes (Piquot et al 1998;Gabriel and Bü rger 2000;Stö cklin and Winkler 2004). However, the evolution of the balance between both modes of reproduction in plants is still poorly understood (Eckert 2002;Fischer and van Kleunen 2002).…”