An experimental study of hybridization and pollination in <i>Salix</i> (willow)

Argus, George W.

doi:10.1139/b74-212

Cited by 64 publications

(37 citation statements)

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“…These willow species coexist broadly throughout their range, with S. eriocephala being found more commonly along streams and S. sericea being more common in swampy areas. However, they occur together in both habitats, and interspecific hybrids are common (Argus 1986). At our swampy field site, S. eriocephala and hybrids tend to occur closer to the stream, whereas S. sericea occurs throughout the site including drier areas (see below).…”

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Fitness and Genetic Architecture of Parent and Hybrid Willows in Common Gardens

et al. 2006

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Abstract. Models of hybrid zone dynamics incorporate different patterns of hybrid fitness relative to parental species fitness. An important but understudied source of variation underlying these fitness differences is the environment. We investigated the performance of two willow species and their F 1 , F 2 , and backcross hybrids using a common-garden experiment with six replicated gardens that differed in soil moisture. Aboveground biomass, catkin production, seed production per catkin, and seed germination rate were significantly different among genetic classes. For aboveground biomass and catkin production, hybrids generally had intermediate or inferior performance compared to parent species. Salix eriocephala had the highest performance for all performance measures, but in two gardens F 1 plants had superior or equal performance for aboveground biomass and female catkin production. Salix eriocephala and backcrosses to S. eriocephala had the highest numbers of filled seeds per catkin and the highest estimates of total fitness in all gardens. Measures of filled seeds per catkin and germination rate tend to support the model of endogenous hybrid unfitness, and these two measures had major effects on estimates of total seed production per catkin. We also estimated how the two willow species differ genetically in these fitness measures using line cross analysis. We found a complex genetic architecture underlying the fitness differences between species that involved additive, dominance, and epistatic genetic effects for all fitness measures. The environment was important in the expression of these genetic differences, because the type of epistasis differed among the gardens for aboveground biomass and for female catkin production. These findings suggest that fine-scale environmental variation can have a significant impact on hybrid fitness in hybrid zones where parents and hybrids are widely interspersed.

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Fitness and Genetic Architecture of Parent and Hybrid Willows in Common Gardens

et al. 2006

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“…It is probable that hermaphrodites in willows are self-compatible, and large pollinators such as bees or even the common Blue Tit Cyanistes caeruleus [48] may transfer pollen grains to stigmas between flowers on the same catkin. Such a transfer is facilitated in Salix because some species are both wind and insect pollinated (e.g., [49,50]). Wind pollination is facilitated in this genus by early flowering (before leaf development) and the release of pollen into the air.…”

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confidence: 99%

Are hermaphrodites better adapted to the colonization process in trioecious populations of Salix myrsinifolia?

Mirski

Brzosko

2015

Acta Soc Bot Pol

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IntroductionSexual dimorphism in plants is characterized not only by the production of androecia vs. gynoecia (primary sexual characters) but also by a range of other morphological differences (secondary sexual characters) among sexual morphs. Males and females can also vary in traits such as individual leaf and flower size, the number of flowers, resource allocation and many others ([1,2] and references therein). Moreover, both sexes can be differentially influenced by biotic conditions such as parasitism and herbivory, which affect their competitive ability [3]. The latter is especially important [4] and even considered a potential force in the evolution of separate sexes from hermaphroditism [5]. Furthermore, differences in resource allocation and reproductive morphology may drive opposite sexes to specialization in different habitats (sexual specialization) and results in the spatial segregation of sexes [6]. It is likely that the phenomenon of spatial segregation of sexes may also be a result of inter-sexual competition, which may impact plants more significantly than intra-sexual competition [7].Size dimorphism is considered to be a result of different resource allocation in sexually dimorphic plants [8]. In general, females are considered to grow less due to a greater investment in reproduction, which was especially proven for woody plants [8][9][10][11]. Other factors, such as local mate competition, geitonogamy, and pollination vectors [12,13], can also influence the benefits of sex-size relations, depending on the species. Size itself positively correlates with flower production [14], the number of offspring [15] and survival probability [16,17] and therefore might serve as a good indicator of competitive abilities.Sex-dependent resource allocation is one of the evolutionary forces through which dioecy evolves via the gynodioecy pathway [18]. Although the evolution of separate sexes in plants has many advantages [19], drawbacks to sexual systems involving hermaphrodites have been recorded in several tree genera, mostly in Salix [20] and Acer [21][22][23], as well as in Taxus [24], Rhamnus and Populus [25]. Why is this turnover favorable if it is a step back in the evolution of sexual systems? It appears that introducing hermaphrodite individuals to previously dioecious populations may be favored in unstable conditions, such as under skewed sex ratios [26], landscape fragmentation [27], lack of pollinators [28], significant habitat alteration [29], or when the opportunities for cross-fertilization are rare, e.g., under the * Corresponding author. Email: p.mirski@uwb.edu.plHandling Editor: Aleksandra Samecka-Cymerman ORIGINAL RESEARCH PAPER Acta Soc Bot Pol 84(2): 167-175 DOI: 10.5586/asbp.2015.013 Received: 2014-11-17 Accepted: 2015-03-15 Published electronically: 2015 Are hermaphrodites better adapted to the colonization process in trioecious populations of Salix myrsinifolia?Paweł Mirski*, Emilia BrzoskoInstitute of Biology, University of Bialystok, Ciołkowskiego 1j, 15-245 Białystok, Poland Abstrac...

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“…Most species flower from early spring to early summer. Salix flowers are predominantly insect-pollinated, but wind-pollination takes place as well (Argus 1974;Vroege and Stelleman 1990;Peeters and Totland 1999;Tamura and Kudo 2000;Karrenberg et al 2002). Imperfect flowers are borne on mostly erect catkins (aments), and appear before or with leaves.…”

Section: Flowers and Seedsmentioning

confidence: 99%