Relevance of the Study of Technetium Accumulation and Speciation in Plants

Desmet, G.

doi:10.1007/978-94-009-4189-2_16

Cited by 2 publications

(1 citation statement)

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“…1 m) (Hartmann, 1978;Linder, 1985;Ihlenfeldt, 1994;Parolin, 2001;Ellis & al., 2006). Diversification in this group appears to involve early, rapid adaptive divergence based on soils and flowering time, followed by repeated speciation based on limited dispersal (Desmet & al., 1998;Klak & al., 2004;Ellis & Weis, 2006;Ellis & al., 2006). Key innovations-including wide-band tracheids and cylindrical or trigonal leaf cross-sections-that reduce the impact of drought may have also played a role in fostering rapid diversification in this group (Klak & al., 2004).…”

Section: Ecological Determinants Of Net Diversification Rates and Ovementioning

confidence: 99%

Ecology of plant speciation

Givnish

2010

TAXON

248

236

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Ecology affects each of the three principal processes leading to speciation: genetic differentiation among populations within species, acquisition of reproductive isolation among populations, and the rise of ecological differentiation among such populations, allowing them to coexist. Until recently, however, the ties between ecology and speciation in plants have received relatively little attention. This paper reviews some exciting new insights into the role of ecology in speciation, focusing on the angiosperms. I consider five main topics, including (1) the determinants of the spatial scale of genetic differentiation within species; (2) the role and limits of adaptive radiation in increasing net rates of plant diversification; (3) the potential role of ecological speciation; (4) the contributions of hybridization to speciation, adaptive radiation, and the ecological breadth of clades; and (5) the ecological determinants of net diversification rate for individual lineages, and of the species richness for regional floras. Limited dispersal, especially of seeds, favors genetic differentiation at small spatial scales and is likely to foster rapid speciation and narrow endemism. Metaanalyses show that the minimum area required for in situ speciation on islands increases with the spatial scale of gene flow in various organisms. In angiosperms, fleshy fruits dispersed by vertebrates often increase the distance over which seeds are dispersed, but can decrease it in forest understories. Nutrient‐poor soils should work against the evolution of fleshy fruits and promote speciation and narrow endemism. Selection for adaptation to different conditions drives adaptive radiation, the rise of a diversity of ecological roles and attendant adaptations within a lineage. On islands, adaptive radiation often leads to woodiness, monocarpy, developmental heterophylly, and sexual dimorphism, as well as differences in habitat, growth form, and floral morphology. Adaptive radiation appears to accelerate speciation in only some plant clades. Extensive radiation in some lineages has been ascribed to early colonization, large amounts of heritable genetic variation, “genetic lines of least resistance” upon which selection could act, absence of potential competitors, and possession of “key innovations” that provide access to novel resources. To these should be added large island area, organismal abundance, saturation of ecological space, and the synergism action of limited dispersal and divergent selection producing parallel radiations in isolated regions. Data for Hawaiian lobeliads suggest that withinisland species richness of Cyanea—involving divergence in elevation and flower tube length—saturates within 0.6 and 1.5 Ma. Adaptive radiation in pollinators is an important mechanism of ecological speciation: adaptation to different pollinators leads to pollinator partitioning and reproductive isolation. Selection for longer nectar spurs and pollinator mouth parts led to increased speciation in Aquilegia and other groups. A similar ...

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