Evolution of reproductive isolation in plants

Abstract

Reproductive isolation is essential for the process of speciation and much has been learned in recent years about the ecology and underlying genetics of reproductive barriers. But plant species are typically isolated not by a single factor, but by a large number of different pre-and postzygotic barriers, and their potentially complex interactions. This phenomenon has often been ignored to date. Recent studies of the relative importance of different isolating barriers between plant species pairs concluded that prezygotic isolation is much stronger than postzygotic isolation. But studies of the patterns of reproductive isolation in plants did not find that prezygotic isolation evolves faster than postzygotic isolation, in contrast to most animals. This may be due to the multiple premating barriers that isolate most species pairs, some of which may be controlled by few genes of major effect and evolve rapidly, whereas others have a complex genetic architecture and evolve more slowly. Intrinsic postzygotic isolation in plants is correlated with genetic divergence, but some instrinsic postzygotic barriers evolve rapidly and are polymorphic within species. Extrinsic postzygotic barriers are rarely included in estimates of different components of reproductive isolation. Much remains to be learned about ecological and molecular interactions among isolating barriers. The role of reinforcement and reproductive character displacement in the evolution of premating barriers is an open topic that deserves further study. At the molecular level, chromosomal and genic isolation factors may be associated and act in concert to mediate reproductive isolation, but their interactions are only starting to be explored.

DESENVOLVIMENTO DE MUDAS DE MARACUJAZEIRO-AZEDO ENXERTADAS EM ESPÉCIES SILVESTRES DE Passiflora

“…A introgressão de genes de resistência de espécies silvestres pode ser possível em alguns casos por meio de hibridação , embora os híbridos interespecíficos nem sempre sejam férteis (WiDMeR et al, 2009) Vários testes têm sido realizados para o maracujazeiro-azedo buscando resistência a doenças de solos em espécies silvestres de Passiflora (MeneZeS et al, 1994;Roncatto et al, 2004;cavicHioli et al, 2011b), além de testarem a metodologia e a compatibilidade da enxertia de P. edulis sobre estas espécies (cHaveS et al, 2004;JunQueiRa et al, 2006;cavicHioli;coRRÊa, 2009;cavicHioli et al, 2009;lenZa et al, 2009;nogueiRa FilHo et al, 2010;cavicHioli et al, 2011a,b;Roncatto et al, 2011). como, além da resistência a doenças, os porta-enxertos devem ter qualidades fitotécnicas adequadas, mais trabalhos devem ser realizados visando a auxiliar na escolha ou no desenvolvimento de porta-enxertos para P. edulis, avaliando o potencial de outras espécies silvestres como porta-enxertos e o desenvolvimento das mudas enxertadas.…”

Range-wide patterns of nuclear and chloroplast DNA diversity in Vriesea gigantea (Bromeliaceae), a neotropical forest species

“…Despite an increasing interest in the evolutionary genetics of plant diversification in the neotropics (Rull, 2006;Barbará et al, 2008;Widmer et al, 2009), surprisingly little background information is available on the phylogeographic structure and patterns of gene flow across species' ranges in these ecosystems, compared with the temperate regions of the world (Hewitt, 2004). Biogeographic studies of taxa from the Amazon (Aleixo, 2004), the Andes (Pennington et al, 2002;Speranza et al, 2007) and the Brazilian Atlantic Rainforest (da Silva et al, 2004;Carnaval and Moritz, 2008) indicate the evolutionary complexity of the Quaternary history of South America, with a prominent role of range contractions and expansions due to the climatic changes of the Pleistocene.…”

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

“…Experimental investigations on the evolution and nature of reproductive isolation barriers can provide insights into the process of diversification (Coyne & Orr, 1998, 2004; Moyle et al., 2004; Schemske, 2010; Scopece et al., 2007, 2008; Widmer et al., 2009). In our study, floral isolation mediated by floral scent appears to be the only significant barrier to gene flow between two recently diverged orchid species.…”