Silene as a model system in ecology and evolution

Abstract

The genus Silene, studied by Darwin, Mendel and other early scientists, is re-emerging as a system for studying interrelated questions in ecology, evolution and developmental biology. These questions include sex chromosome evolution, epigenetic control of sex expression, genomic conflict and speciation. Its well-studied interactions with the pathogen Microbotryum has made Silene a model for the evolution and dynamics of disease in natural systems, and its interactions with herbivores have increased our understanding of multi-trophic ecological processes and the evolution of invasiveness. Molecular tools are now providing new approaches to many of these classical yet unresolved problems, and new progress is being made through combining phylogenetic, genomic and molecular evolutionary studies with ecological and phenotypic data. The model role of a non-model organismThe genus Silene (Caryophyllaceae), with a tradition of genetical and ecological studies dating back to Mendel and Darwin, has remarkably many interesting features. First, the species in the genus vary widely in their breeding systems and ecology. Second, several members of this mainly holarctic genus can be easily bred, and have short life cycles, and are thus convenient for experimental and field studies. Genomic resources are now becoming increasingly available in Silene, making genetic, quantitative genetic and molecular studies possible. A strength of Silene as a model system, compared with many classical model organisms, is that researchers can rely on a large number of ecological studies encompassing biotic interactions with sexually transmitted fungi, pollinators and herbivores. It is the wealth of ecological and other earlier knowledge that makes the genus Silene important for studying many biological questions, including the suppression of recombination during sex chromosome evolution, sexually antagonistic selection in an organism that is not an animal, epigenetic processes in flower development, speciation and reproductive isolation, multi-trophic interactions, disease ecology and biological invasions.Thanks to the classical genetic and ecological work on Silene, new progress can now be made in studying some of these important unresolved questions in biology with the aid of modern molecular tools. That new model systems with accessible and well-studied ecology open fruitful avenues for investigation is illustrated also by Mimulus (Wu et al., 2008) and the ongoing efforts to develop genomic resources in an increasing number of different systems. In the following, we outline the unique features of the Silene system, and describe active research areas and future directions, highlighting new advances and work in progress. Evolution of sexual systemsPlants show remarkable diversity in their sexual and mating systems, ranging from hermaphroditism to dioecy, from self-incompatible hermaphroditism to hermaphroditism in which individuals possess a capacity to self-fertilize, but which often show complex mechanisms to promote outcrossing (Darwin, 18...

Benefits and costs to pollinating, seed-eating insects: the effect of flower size and fruit abortion on larval performance

“…The white campion Silene latifolia (Poiret) [= Silene alba (Miller) Krauss, = Melandrium album (Miller) Garcke; Caryophyllaceae] is a short-lived perennial, dioecious plant native to Europe and found in disturbed habitats (Goulson and Jerrim 1997;Bernasconi et al 2009). S. latifolia is dioecious and sexually dimorphic for several traits, including calyx width and floral display (Delph et al 2002).…”

“…Unlike the yucca/yucca moth and senita cactus/senita moth associations (obligate mutualism; Fleming and Holland 1998), the interaction studied here between Silene latifolia and Hadena bicruris is not obligate and is therefore considered to be a basal form of nursery pollination (Dufaÿ and Anstett 2003;Bernasconi et al 2009). However, there is evidence for potential specialization in this system, at least to some degree: the two species have similar geographic distributions, flowering and oviposition are synchronous (Biere and Honders 1996;Bopp and Gottsberger 2004;Wright and Meagher 2003), moths respond to specific scent compounds emitted by the flowers (Dotterl et al 2006), and H. bicruris larvae grow better on S. latifolia than on other host species (Bopp and Gottsberger 2004).…”

Patterns of cyto-nuclear linkage disequilibrium in Silene latifolia: genomic heterogeneity and temporal stability

“…Silene latifolia is a dioecious, insect-pollinated plant that has been the subject of a considerable number of studies that focus on local population genetic structure and the effects of metapopulation dynamics on that structure (McCauley, 1994;McCauley et al, 1995McCauley et al, , 1996Bernasconi et al, 2009). Many of these studies were conducted 415 years ago, before the introduction of most of the DNA-based genetic markers used in studies of population structure today.…”

Patterns of Neutral Genetic Variation on Recombining Sex Chromosomes

“…We then study 1 the consequences of the invasion of a neo-Y chromosome that converts an ancestral pair of autosomes into sex chromosomes. This model is motivated by the numerous species of plants (see Ming and Moore 2007;Bernasconi et al 2009) and animals (see Peichel et al 2004;Mank et al 2006;Cnaani et al 2008;McAllister et al 2008;Takehana et al 2008;Kitano et al 2009;Ser et al 2010) in which sex chromosomes have been recently derived from autosomes (see also van Doorn and Kirkpatrick 2007).…”