Plant Speciation

Rieseberg, Loren H.; Willis, John H.

doi:10.1126/science.1137729

Cited by 996 publications

(960 citation statements)

References 62 publications

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“…So if we generalize the gene dispersal results from P. punctata to these species, it appears that low migration rates may have contributed to allopatric and parapatric speciation in this clade (Cowling and Lombard 2002;Rieseberg and Willis 2007). The relatively low estimates of genetic diVerentiation among populations, in contrast, suggest a mechanism is operating to maintain signiWcant gene migration among populations.…”

Section: Discussionmentioning

confidence: 97%

Experimental biogeography: the role of environmental gradients in high geographic diversity in Cape Proteaceae

et al. 2009

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One of the fundamental dimensions of biodiversity is the rate of species turnover across geographic distance. The Cape Floristic Region of South Africa has exceptionally high geographic species turnover, much of which is associated with groups of closely related species with mostly or completely non-overlapping distributions. A basic unresolved question about biodiversity in this global hotspot is the relative importance of ecological gradients in generating and maintaining high geographic turnover in the region. We used reciprocal transplant experiments to test the extent to which abiotic environmental factors may limit the distributions of a group of closely related species in the genus Protea (Proteaceae), and thus elevate species turnover in this diverse, iconic family. We tested whether these species have a "home site advantage" in demographic rates (germination, growth, mortality), and also parameterized stage-structured demographic models for the species. Two of the three native species were predicted to have a demographic advantage at their home sites. The models also predicted, however, that species could maintain positive population growth rates at sites beyond their current distribution limits. Thus the experiment suggests that abiotic limitation under current environmental conditions does not fully explain the observed distribution limits or resulting biogeographic pattern. One potentially important mechanism is dispersal limitation, which is consistent with estimates based on genetic data and mechanistic dispersal models, though other mechanisms including competition may also play a role.

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Section: Discussionmentioning

confidence: 97%

Experimental biogeography: the role of environmental gradients in high geographic diversity in Cape Proteaceae

et al. 2009

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“…The recent research about the natural hybrid P. 9 intortusifolius (Du et al 2009) has confirmed the existence of the bidirectional hybridization in natural populations. Traditionally, conspecific pollen was considered to be advantageous in fertilization compared with nonconspecific pollen (Rieseberg and Willis 2007). Such conspecific advantages, however, were not significant in these two Potamogeton species.…”

Section: Absence Of Prezygotic Barriers In Interspecific Crossesmentioning

confidence: 99%

“…Many different mechanisms, such as ecological separation, mating barriers, and inviability or infertility of hybrids, can prevent interspecific hybridization. Prezygotic barriers, which prevent interspecific fertilization, are considered to be more important in plants than postzygotic barriers (Rieseberg and Willis 2007). So we focused on the prezygotic barriers in Potamogeton and tried to explain the high frequency of interspecific hybrids in this genus by critical experimental hybridization.…”

Section: Introductionmentioning

confidence: 99%

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When interspecific prezygotic barriers break down: hybridization between two Potamogeton species (P. wrightii and P. perfoliatus) and comparison of the artificial and natural hybrids

Zhang

et al. 2011

Plant Syst Evol

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Interspecific hybridization played an important role in speciation and evolution of angiosperms. Although the widespread occurrence of natural hybrids in the genus Potamogeton has been studied intensively, few successful experimental hybridization studies have been reported in this genus. In the present study, critical experimental hybridization was conducted using Potamogeton 9 intortusifolius, a natural hybrid widely distributed in China, and its parents (P. perfoliatus and P. wrightii). The absence of prezygotic barriers between P. wrightii and P. perfoliatus was observed, which contributes to the frequent hybridization of these species in nature. The pollen tube growth rates of P. perfoliatus were much faster than those of P. wrightii in the style of that species. However, the conspecific pollen tubes were competitively advantageous in P. perfoliatus styles. The interspecific hybridization could be applied bidirectionally, and 28 F1 hybrid individuals were successfully obtained from P. wrightii 9 P. perfoliatus, despite the low germination possibility of the hybrid seeds. Both the artificial and natural hybrids exhibited intermediate morphological characters but presented much lower fertility. The sterility of P. 9 intortusifolius is mainly due to its low female fitness. However, the offspring from P. wrightii 9 P. 9 intortusifolius indicated the potential for backcrossing in nature. This is the most successful attempt at artificial hybridization in this genus so far. The possible route for restoration of fertility and the fitness of the hybrids are also discussed in this paper.

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“…Depending on the timing of their onset, reproductive isolation barriers are classified as either pre‐zygotic (e.g., behavioral, mechanical, or gametic isolation) or post‐zygotic (e.g., hybrid sterility or ecological inviability) (Coyne & Orr, 2004). The local maintenance of distinct species usually requires a combination of different types of barriers, and their hierarchical importance is often taxon‐specific (Coyne & Orr, 1998; Rieseberg & Willis, 2007). …”

Section: Introductionmentioning

confidence: 99%

Floral scent and species divergence in a pair of sexually deceptive orchids

Gervasi

Selosse

Sauve

et al. 2017

Ecology and Evolution

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Speciation is typically accompanied by the formation of isolation barriers between lineages. Commonly, reproductive barriers are separated into pre‐ and post‐zygotic mechanisms that can evolve with different speed. In this study, we measured the strength of different reproductive barriers in two closely related, sympatric orchids of the Ophrys insectifera group, namely Ophrys insectifera and Ophrys aymoninii to infer possible mechanisms of speciation. We quantified pre‐ and post‐pollination barriers through observation of pollen flow, by performing artificial inter‐ and intraspecific crosses and analyzing scent bouquets. Additionally, we investigated differences in mycorrhizal fungi as a potential extrinsic factor of post‐zygotic isolation. Our results show that floral isolation mediated by the attraction of different pollinators acts apparently as the sole reproductive barrier between the two orchid species, with later‐acting intrinsic barriers seemingly absent. Also, the two orchids share most of their fungal mycorrhizal partners in sympatry, suggesting little or no importance of mycorrhizal symbiosis in reproductive isolation. Key traits underlying floral isolation were two alkenes and wax ester, present predominantly in the floral scent of O. aymoninii. These compounds, when applied to flowers of O. insectifera, triggered attraction and a copulation attempt of the bee pollinator of O. aymoninii and thus led to the (partial) breakdown of floral isolation. Based on our results, we suggest that adaptation to different pollinators, mediated by floral scent, underlies species isolation in this plant group. Pollinator switches may be promoted by low pollination success of individuals in dense patches of plants, an assumption that we also confirmed in our study.

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Plant Speciation

Cited by 996 publications

References 62 publications

Experimental biogeography: the role of environmental gradients in high geographic diversity in Cape Proteaceae

Experimental biogeography: the role of environmental gradients in high geographic diversity in Cape Proteaceae

When interspecific prezygotic barriers break down: hybridization between two Potamogeton species (P. wrightii and P. perfoliatus) and comparison of the artificial and natural hybrids

Floral scent and species divergence in a pair of sexually deceptive orchids

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