@article{LumagaCozzolinoKocyanetal.2014,
  author    = {Lumaga, Maria Rosaria Barone and Cozzolino, Salvatore and Kocyan, Alexander and Menale, Bruno and Rudall, Paula J.},
  title     = {Exine micromorphology and ultrastructure in Neottieae (Epidendroideae, Orchidaceae)},
  series = {Plant systematics and evolution},
  volume    = {300},
  journal   = {Plant systematics and evolution},
  number    = {3},
  publisher = {Springer},
  address   = {Wien},
  issn      = {0378-2697},
  doi       = {10.1007/s00606-013-0899-2},
  pages     = {505 -- 515},
  year      = {2014},
  abstract  = {The diverse epidendroid orchid tribe Neottieae is characterized by multiple transitions between autotrophy and mycoheterotrophy, allogamous and autogamous mating systems, pollen released as tetrads or monads, and pollen exine tectate or semitectate. We use transmission and scanning electron microscopy on pollen of ten species of Neottieae to investigate whether the differences in pollen aggregation and exine micromorphology and ultrastructure reflect phylogenetic relationships, or whether this variation is subject to ecological constraints. Our results showed that differences in exine micromorphology are mostly concordant with phylogenetic relationships in Neottieae, i.e. an ascending tendency of pollen ornamentation from tectate (Cephalanthera) to semitectate (e.g. Neottia). In contrast, pollen aggregation, when plotted on the most recent phylogeny, shows repeated transitions between monads and tetrads that could be related to ecological constraints. Tetrads are present in species that are nectar rewarding, whereas monads are common in deceptive species. Cephalanthera is characterized by recalcitrant pollen, including the frequent occurrence of collapsed pollen. In this genus, the observed shifts from allogamous to autogamous or cleistogamous mating systems could help to reduce pollen damage caused by exposure to dry habitats.},
  language  = {en}
}
@article{LauterbachRistowGemeinholzer2012,
  author    = {Lauterbach, Daniel and Ristow, Michael and Gemeinholzer, Birgit},
  title     = {Population genetics and fitness in fragmented populations of the dioecious and endangered Silene otites (Caryophyllaceae)},
  series = {Plant systematics and evolution},
  volume    = {298},
  journal   = {Plant systematics and evolution},
  number    = {1},
  publisher = {Springer},
  address   = {Wien},
  issn      = {0378-2697},
  doi       = {10.1007/s00606-011-0533-0},
  pages     = {155 -- 164},
  year      = {2012},
  abstract  = {Population fragmentation is often correlated with loss of genetic diversity and reduced fitness. Obligate out-crossing (dioecy) is expected to enhance genetic diversity, reduce genetic differentiation, and avoid inbreeding depression through frequent gene flow. However, in highly fragmented populations dioecy has only diminishing effects upon genetic structure as pollination limitations (e.g. flight distance of pollinators) most often restrict inter-population gene flow in insect pollinated species. In fragmented dry grasslands in northeastern Germany, we analysed genetic structure, fitness, and habitat quality of the endangered dioecious Silene otites (Caryophyllaceae). Using AFLP markers, a high level of differentiation among ten populations was found (F (st) = 0.36), while the intra-population genetic diversities (H (E) = 0.165-0.240) were similar as compared to hermaphroditic species. There was neither a correlation between geographic and genetic distance nor between genetic diversity and population size, which indicates reduced gene flow among populations and random genetic drift. Plant size was positively correlated with genetic diversity. Seed set and number of juveniles were positively related to population size. Higher total coverage resulted in reduced plant fitness, and the number of juveniles was negatively correlated to cryptogam cover. Additionally, we found a sex ratio bias towards more male plants in larger populations. Overall, our results indicate that on a regional geographic scale dioecy does not necessarily prevent genetic erosion in the case of habitat fragmentation, especially in the absence of long distance seed and pollen dispersal capacity.},
  language  = {en}
}