Javier Fuertes-Aguilar

Phylogeny of the Macaronesian endemic Crambe section Dendrocrambe (Brassicaceae) based on internal transcribed spacer sequences of nuclear ribosomal DNA

The 14 species of Crambe L. sect. Dendrocrambe DC. (Brassicaceae) form a monophyletic group endemic to the Canary and Madeira archipelagos. Both parsimony and maximum likelihood analyses of sequence data from the two internal transcribed spacer regions of nuclear ribosomal DNA were used to estimate phylogenetic relationships within this section. These analyses support the monophyly of three major clades. No clade is restricted to a single island, and therefore it appears that inter-island colonization has been the main avenue for speciation in these two archipelagos. The two species endemic to Fuerteventura (C. sventenii) and Madeira (C. fruticosa) comprise a clade, providing the first evidence for a floristic link between the Eastern Canary Islands and the archipelago of Madeira. Both maximum likelihood and weighted parsimony analyses show that this clade is sister to the two other clades, although bootstrap support for this relationship is weak. Parsimony optimizations of ecological zones and island distribution suggest a colonization route from the low-altitude areas of the lowland scrub toward the high-elevation areas of the laurel and pine forests. In addition, Tenerife is likely the ancestral island for species endemic to the five westernmost islands of Gran Canaria, La Gomera, El Hierro, La Palma, and Tenerife.

Molecular Evidence from Chloroplast and Nuclear Markers for Multiple Colonizations of Lavatera (Malvaceae) in the Canary Islands

Abstract A molecular phylogenetic study based on chloroplast DNA restriction site and ITS sequence data shows that the two Macaronesian endemics, Lavatera phoenicea and Lavatera acerifolia, represent two independent introductions into the Canary Islands. The molecular phylogenies, combined with morphological, ecological, and biogeographical data, indicate that Lavatera phoenicea may be a bird-pollinated relict of an ancient laurel forest. Lavatera acerifolia, however, is nested in a derived clade of the Lavatera-Malva taxa from the Mediterranean region, suggesting a more recent introduction into the Canary Islands. Incongruence between chloroplast and nuclear phylogenies suggests that hybridization may have played a role in the evolution of L. acerifolia. Several features of L. phoenicea, such as corolla color and high nectar production, appear to be plesiomorphic and are still present because of historical constraints. In contrast, woodiness is a derived feature that originated as an adaptation to insular conditions. Communicating Editor: James R. Manhart

Pollinator shifts drive petal epidermal evolution on the Macaronesian Islands bird-flowered species.

Pollinator shifts are considered to drive floral trait evolution, yet little is still known about the modifications of petal epidermal surface at a biogeographic region scale. Here we investigated how independent shifts from insects to passerine birds in the Macaronesian Islands consistently modified this floral trait (i.e. absence of papillate cells). Using current phylogenies and extensive evidence from field observations, we selected a total of 81 plant species and subspecies for petal microscopy and comparative analysis, including 19 of the 23 insular species pollinated by opportunistic passerine birds (Macaronesian bird-flowered element). Species relying on passerine birds as the most effective pollinators (bird-pollinated) independently evolved at least five times and in all instances associated with a loss of papillate cells, whereas species with a mixed pollination system (birds plus insects and/or other vertebrates) evolved at least five times in Macaronesia and papillate cells were lost in only 25% of these transitions. Our findings suggest that petal micromorphology is a labile trait during pollinator shifts and that papillate cells tend to be absent on those species where pollinators have limited mechanical interaction with flowers, including opportunistic passerine birds that forage by hovering or from the ground.

Foliar secretory structures in Crotoneae (Euphorbiaceae): Diversity, anatomy, and evolutionary significance

PREMISE OF THE STUDY Phylogenetic and morphological studies have helped clarify the systematics of large and complex groups such as the tribe Crotoneae (Euphorbiaceae). However, very little is known about the diversity, structure, and function of anatomical features in this tribe. Crotoneae comprises the species-rich pantropical genus Croton and six small neotropical genera. Here we characterized the anatomy of leaf secretory structures in members of this tribe and explored their function and evolutionary significance. METHODS Young and mature leaves of 26 species were studied using standard anatomical light microscopy techniques. Three sections of Croton and one representative of Brasiliocroton and Astraea were sampled. KEY RESULTS We identified five types of secretory structures: laticifers, colleters, extrafloral nectaries, idioblasts, and secretory trichomes. Laticifers were present in all species studied except Croton alabamensis, which instead presented secretory parenchyma cells. Articulated laticifers are reported in Crotoneae for the first time. Colleters of the standard type were observed in the majority of the sampled taxa. Extrafloral nectaries were present in section Cleodora and in B. mamoninha, but absent in section Lamprocroton and Astraea lobata. Idioblasts were spread throughout the palisade and/or spongy parenchyma in most of the studied species. Secretory trichomes were restricted to Lamprocroton except for C. imbricatus. CONCLUSIONS This study revealed a high diversity of secretory structures, including novel ones, in one of the largest clades of Euphorbiaceae. Our results are promising for investigations on the anatomical and ecophysiological bases of species diversification within Euphorbiaceae.

Evolution and Expression Patterns of CYC/TB1 Genes in Anacyclus: Phylogenetic Insights for Floral Symmetry Genes in Asteraceae

Homologs of the CYC/TB1 gene family have been independently recruited many times across the eudicots to control aspects of floral symmetry The family Asteraceae exhibits the largest known diversification in this gene paralog family accompanied by a parallel morphological floral richness in its specialized head-like inflorescence. In Asteraceae, whether or not CYC/TB1 gene floral symmetry function is preserved along organismic and gene lineages is unknown. In this study, we used phylogenetic, structural and expression analyses focused on the highly derived genus Anacyclus (tribe Anthemidae) to address this question. Phylogenetic reconstruction recovered eight main gene lineages present in Asteraceae: two from CYC1, four from CYC2 and two from CYC3-like genes. The species phylogeny was recovered in most of the gene lineages, allowing the delimitation of orthologous sets of CYC/TB1 genes in Asteraceae. Quantitative real-time PCR analysis indicated that in Anacyclus three of the four isolated CYC2 genes are more highly expressed in ray flowers. The expression of the four AcCYC2 genes overlaps in several organs including the ligule of ray flowers, as well as in anthers and ovules throughout development.

Ornithophily for the nonspecialist: Differential pollination efficiency of the Macaronesian island paleoendemic Navaea phoenicea (Malvaceae) by generalist passerines

PREMISE OF THE STUDY A bird pollination syndrome exists in the Canary Islands archipelago across independent plant lineages despite the absence of specialist birds. The pollination efficiency of current floral visitors remains unknown for many plant species despite this being a fundamental factor in testing hypotheses about the origin of the syndrome. Here, we studied the components of pollination efficiency in the paleoendemic Navaea phoenicea, a species exhibiting conspicuous anatomical modifications associated with bird pollination. METHODS We measured the components of the pollination efficiency (PE) of species foraging on flowers. The measured quantitative components were visitation frequency patterns to plants and individual flowers. The qualitative components were the contributions to the fitness of male and female functions (pollen removal and deposition and fruit set). KEY RESULTS Pollination by warbler species was highly efficient, but visit frequency was low; conversely, Canarian chiffchaffs had high visit frequency and low efficiency. Overall PE was almost 0 for blue tits due to disruptive behavior. We also found insects acting as nectar robbers. CONCLUSIONS Pollination efficiency of three of the four bird species visiting flowers of Navaea phoenicea may be high enough to maintain selective pressure on floral traits of a relict pollination syndrome. The behavior of these birds plays a crucial role in their pollination efficiency. Perching, by generalist passerines when visiting N. phoenicea flowers, is the most efficient habit. The frequency and PE of insect visits calls into question their role as legitimate visitors.