References

Variation in pollination performance gradients in a Dudleya species complex can generalization promote floral divergence Functional Ecology, 19, 681-9. Alexandersson R and Johnson SD (2001). Pollinator mediated selection on flower-tube length in a hawk-moth-pollinated Gladiolus (Iridaceae). Proceedings of the Royal Society of London, Series B, 269, 631-6. Archibald JK, Wolfe AD, and Johnson SD (2004). Hybridization and gene flow between a day-and night-flowering species of...

Adaptive radiation

A link between pollinator shifts and diversification is evident from the increasing number of studies that map pollination systems onto phylogenies to interpret their evolution (reviewed by Weller and Sakai 1999 Wilson et al. 2006 Chapter 17). Schluter (2000) proposed that the term adaptive radiation should be used only when diversification in a lineage is characterized by common ancestry, phenotype-environment correlation, trait utility, and rapid speciation. Most of the above examples of...

The geographical pollinator mosaic

Pollinators are distributed unevenly in time and space. Indeed, like all animals, pollinators have restricted ranges, which are often determined by both physical factors, such as altitude, temperature, and rainfall, and by biotic factors, such as vegetation structure and availability of flowering plants (Chapters 6 and 15). The landscape in which plants evolve presents a geographical mosaic of pollinators that is hard to visualize, but is no less important for plant evolution than the...

Petal colour

Petal colour provides a visual cue that stimulates pollinator sensory systems and that selectively attracts certain types of pollinators (Grant 1949 Stebbins 1974 Melendez-Ackerman and Campbell 1998 Hodges et al. 2002). As a corollary, shifts in petal colour can promote speciation through reduced gene flow between colour morphs in association with concurrent changes in pollinator identity (Schemske and Bradshaw 1999 Hodges et al. 2002 Bradshaw and Schemske 2003). Nevertheless, anthocyanins, the...

Geographical modes of pollinatordriven speciation

The three main geographical modes of speciation are allopatric, whereby divergence involves populations that are not linked by gene flow parapatric, in which divergence occurs between adjacent habitats in the face of some gene flow and sym-patric, in which populations diverge in situ through an instantaneous genetic barrier to gene flow or extremely assortative mating. All three modes may apply to pollinator-driven speciation, although only conventional allopatric speciation is strongly...

Direct effects of plant size on fitness gains

Plant size can affect fitness directly, so that returns from a given absolute amount of resources differ for small and large plants Fig. 3.5 . For instance, in a wind-pollinated plant, pollen released from a tall individual may disperse farther and be more successful than pollen from a short individual. Direct effects may also occur in some animal-pollinated plants, because pollinators may prefer taller plants among neighbours Ishii 2004 . With direct effects of plant size, fitness returns per...

Asexual reproduction a neglected mechanism of reproductive assurance

Lloyd 1979, 1980b, 1988 and others have noted repeatedly the evolutionary communalities between self-fertilization and the various forms of asexual reproduction. Like selfing, asexuality has evolved repeatedly in plants. Asexual seed production apomixis has been described in gt 400 flowering plant taxa representing gt 40 families Carman 1997 , and vegetative or clonal asexual reproduction occurs in up to 80 of plant species Klimes et al. 1997 . Yet, compared with the large body of work on the...

Reproductive assurance and selffertilization theoretical context

Despite the obvious advantages of uniparental reproduction, most flowering plants predominantly outcross and relatively few reproduce exclusively via self-fertilization Goodwillie et al. 2005 . Inbreeding depression, the reduced vigour of inbred compared with outbred individuals, is one of the few selective factors strong enough to oppose the automatic selection of selfing Charlesworth and Charlesworth 1987 . Early mathematical models pitting the two-fold gene transmission advantage of selfing...