A reassessment of the phylogeny and circumscription of Zaluzianskya (Scrophulariaceae).

The genus Zaluzianskya (Scrophulariaceae s.s.) encompasses a diversity of floral and ecological traits. However, this diversity, as described by the current taxonomic circumscription of Zaluzianskya, is an underestimate. We present molecular data suggesting that this genus requires expansion via incorporation of species from other genera and recognition of unnamed cryptic species. This study advances prior molecular phylogenies of the southern African genus through the addition of DNA regions and 51 populations that had not previously been sampled in a published phylogeny. A total of 82 species of Zaluzianskya and related genera are included, adding 48 to those previously sampled. Results are presented from analyses of five DNA regions, including nuclear ITS and four rapidly evolving chloroplast regions (trnL-trnF, rpl16, rps16, and trnS-trnfM). Our primary finding is that the genus Phyllopodium is polyphyletic as currently circumscribed, with some species placed within Zaluzianskya and others grouping with Polycarena, indicating the need for further phylogenetic work on these genera. Preliminary support for the incorporation of Reyemia into Zaluzianskya is reinforced here by the first molecular analysis to include both species of Reyemia and a strong sampling of species across Zaluzianskya and major clades of tribe Limoselleae. The two disjunct, tropical African species of Zaluzianskya are also confirmed as members of this genus. Finally, a broad sampling of 21 populations of Z. microsiphon establishes their phylogenetic division into two to five separate lineages. Hybridization, coevolution, and cryptic speciation may each play a role in the evolution of Z. microsiphon. Further resolution within a clade comprising sections Nycterinia and Macrocalyx is needed to better understand their relationships.

Geographical differentiation in floral traits across the distribution range of the Patagonian oil-secreting Calceolaria polyrhiza: do pollinators matter?

BACKGROUND AND AIMS: The underlying evolutionary processes of pollinator-driven floral diversification are still poorly understood. According to the Grant-Stebbins model speciation begins with adaptive local differentiation in the response to spatial heterogeneity in pollinators. Although this crucial process links the micro- and macroevolution of floral adaptation, it has received little attention. In this study geographical phenotypic variation was investigated in Patagonian Calceolaria polyrhiza and its pollinators, two oil-collecting bee species that differ in body size and geographical distribution. METHODS: Patterns of phenotypic variation were examined together with their relationships with pollinators and abiotic factors. Six floral and seven vegetative traits were measured in 45 populations distributed across the entire species range. Climatic and edaphic parameters were determined for 25 selected sites, 2-16 bees per site of the most frequent pollinator species were captured, and a critical flower-bee mechanical fitting trait involved in effective pollination was measured. Geographical patterns of phenotypic and environmental variation were examined using uni- and multivariate analyses. Decoupled geographical variation between corolla area and floral traits related to the mechanical fit of pollinators was explored using a Mantel test. KEY RESULTS: The body length of pollinators and the floral traits related to mechanical fit were strongly correlated with each other. Geographical variation of the mechanical-fit-related traits was decoupled from variation in corolla size; the latter had a geographical pattern consistent with that of the vegetative traits and was mainly affected by climatic gradients. CONCLUSIONS: The results are consistent with pollinators playing a key role in shaping floral phenotype at a geographical scale and promoting the differentiation of two floral ecotypes. The relationship between the critical floral-fit-related trait and bee length remained significant even in models that included various environmental variables and an allometric predictor (corolla area). The abiotic environment also has an important role, mainly affecting floral size. Decoupled geographical variation between floral mechanical-fit-related traits and floral size would represent a strategy to maintain plant-pollinator phenotypic matching in this environmentally heterogeneous area.

Pollen tube guidance by attractant molecules: LUREs.

Sexual reproduction in flowering plants requires pollen-tube guidance, which is thought to be mediated by chemoattractants derived from target ovules. To date, however, no convincing evidence has been reported of a particular molecule being the true attractant. Emerging data indicate that two synergid cells, which are on either side of the egg cell, emit a diffusible, species-specific signal to attract the pollen tube at the last step of pollen-tube guidance. Recently, it was demonstrated that LUREs (LURE1 and LURE2), cysteine-rich polypeptides secreted from the synergid cell, are the key molecules in pollen-tube guidance. In this review, we summarize the mechanism of pollen-tube guidance, with special focus on gametophytic guidance and the attractants.

The Linderniaceae and Gratiolaceae are further lineages distinct from the Scrophulariaceae (Lamiales).

The Lamiales are one of the largest orders of angiosperms, with about 22,000 species. The Scrophulariaceae, as one of their most important families, has recently been shown to be polyphyletic. As a consequence, this family was re-classified and several groups of former scrophulariaceous genera now belong to different families, such as the Calceolariaceae, Plantaginaceae, or Phrymaceae. In the present study, relationships of the genera Craterostigma, Lindernia and its allies, hitherto classified within the Scrophulariaceae, were analyzed. Sequences of the chloroplast trnK intron and the matK gene (approximately 2.5 kb) were generated for representatives of all major lineages of the Lamiales and the former Scrophulariaceae. Bayesian and parsimony analyses revealed two isolated lineages, one of which consists of Lindernia and its allies, the other of Gratiola and allies. Gratiola was previously assumed to be related to Lindernia and was therefore included here. It is proposed to treat the two clades as separate families, Linderniaceae and Gratiolaceae. For the Linderniaceae, several morphological synapomorphies exist in addition to molecular data, such as conspicuous club-shaped stamen appendages.