Ptilothrix bombiformis (Hymenoptera: Apoidea) is a specialist bee belonging to the tribe Emphorini. The emphorine phylogeny suggests that Convolvulacea is the ancestral plant family and independent evolutionary host-switches to several unrelated plant families have occurred. The role of floral scent has been well-characterized in pollination systems involving moths, butterflies, bumblebees, and honeybees, but little is known about how specialist bees mediate host selection, or how host-choice evolved in specialist bees. This research investigates the role of floral scent in host selection by P. bombiformis. Ptilothrix bombiformis has traditionally been classified as a Hibiscus (Malvaceae) oligolege. My research shows that it can now be placed into a more detailed dietary classification as an eclectic oligolege because it also collects pure pollen loads from a distantly-related plant, Ipomoea pandurata (Convolvulaceae). Using dynamic headspace sampling and gas chromatography-mass spectrometry, I obtained floral chemical profiles for Hibiscus moscheutos ssp. lasiocarpos and Ipomoea pandurata. Both flowers contain aliphatics, aromatic compounds, monoterpenes, and sesquiterpenes. The host flowers have 14 shared compounds in their floral scent, which may be responsible for the bees' ability to recognize and utilize I. pandurata, a member or the emphorine ancestral host-plant family. Some of these shared compounds are also found in other emphorine host plants and may be responsible for their constraint in host-use.

How specialist bees distinguish their host plants from co-blooming non-hosts is not well understood, but it is thought that they may be physiologically limited in their ability to recognize the majority of visual and olfactory cues presented by flowering plants. Species in the genus Diadasia collect pollen from just one of five plant families: Cactaceae, Malvaceae, Onagraceae, Asteraceae, and Convolvulaceae. Assuming a common ancestor for all Diadasia specialized on just one plant, this indicates host-switches in the past, and an ability to recognize more than one flowering plant. I hypothesized that host plants of Diadasia share the same visual and olfactory cues, thus enabling past host-switching to novel plant families, and that co-blooming non-hosts are highly dissimilar in terms of scent and visual appearance. I determined the compounds associated with the scent of Malvaceae and Cactaceae host flowers of North American Diadasia. I also evaluated visual cues for these flowers by measuring their full spectrum of reflected wavelengths, as well as select morphometric characters. I determined whether host flowers, regardless of taxa, were more similar to each other than non-hosts that were co-blooming and attractive to other bee species. Finally, I performed electroantennographic and behavioral experiments to assess the relative importance of these cues (visual and olfactory) in natural settings. Diadasia host plants share some chemical and visual characteristics that may in part explain the radiation of this group onto these particular hosts. First, host plants share a suite of scent compounds that are among the least variable across species. Many of these elicited antennal responses and did not decrease visitation when applied to host flowers. In contrast, some compounds produced by non-host flowers are detectable to Diadasia, but Diadasia are repelled by them when they are applied to host flowers. Diadasia host flowers do not share a color profile in common, but there is more reflectance in the bee-uv range as compared to other regions of the light spectrum. Also, Diadasia host flowers have a more contrasting central area that is relatively larger than in non-hosts.

Alstroemeria is an important cut flower and its breeding has been developed focused on aesthetic characteristics and vase life longevity, but little is known about its scent. Five different genotypes were assessed including the non scented cultivars ‘Rebecca’ and ‘Samora’ and the scented cultivars, ‘Sweet Laura’, ‘Ajax’ and the species A. caryophyllaea. The scented Alstroemerias emitted the terpenoids: isocaryophyllene and ocimene as the major floral volatile compounds. Characterization of an Alstroemeria TPS (ALSTER) was based on four ESTs previously found in A. cv ‘Rebecca’. Rapid amplification of cDNA ends (RACE) was performed and the full length ORF was used for characterizations of the genomic organization and amino acid sequences (phylogenetic analysis). ALSTER genomic region contains five introns and six exons. This unique genomic organization classified ALSTER as a member of the class III with a merged 5-6 exon. The deduced amino acid sequence was classified into the subfamily TPS-b. A functional analysis showed enzymatic activity of ALSTER with geranyl diphosphate (GPP) and the monoterpene myrcene was the only product obtained. Gene expression evaluated through real time and semi q RT-PCR on eight different stages of development (SO to S7) showed high expression of ALSTER at around S2 - S4 in the scented Alstroemerias, coinciding with high scent emission perceived and also with the maturation of reproductive organs. Evaluations through surveys focused on level of liking of floral scent, were performed finding positive correlations between floral scent liking and floral appearance liking and between floral scent liking and floral scent intensity. Finally, 17 new lines of A. caryophyllaea were evaluated in terms of their morphology, phenology and productivity. Although none of them were suitable for the market because of their low productivity, short stems and small flowers, they were all scented and identified as promising starting points for breeding purposes.

Catasetum é um gênero Neotropical com cerca de 130 espécies praticamente indistinguíveis quanto à morfologia vegetativa. Suas flores são primariamente unissexuais. As flores masculinas exibem uma excepcional variação morfológica e apresentam estaminódios modificados característicos deste gênero, que é tradicionalmente citado pela polinização exclusiva por abelhas euglossine. Este estudo avaliou a evolução dos principais atributos florais em Catasetum. Para isso, uma hipótese filogenética foi reconstruída utilizando matrizes individuais e combinadas de DNA nuclear e plastidial. Foram sequenciadas três regiões (ITS, rpS16 e trnL-F) para 80 espécies de Catasetum e 25 grupos externos. O gênero é monofilético e irmão de Clowesia em todas as análises. Alguns relacionamentos tiveram alto suporte. Nenhuma das classificações infragenéricas tradicionais pode ser reconhecida na filogenia. A partir deste resultado foi possível observar que a história evolutiva compreendeu várias reversões e convergências de caráter entre as espécies. O estado plesiomórfico e algumas tendências evolutivas são apresentados. As análises morfo-anatômicas e histoquímicas florais utilizaram flores frescas ou fixadas, cujo labelo foi seccionado e corado com Lugol 1% e Vermelho de Sudão III ou IV, sendo examinados através de microscopia de luz. Estas análises revelaram a tendência de aumento na complexidade do labelo apenas em flores masculinas. Também foi possível observar a relação direta entre a morfologia do labelo e a distribuição do tecido secretor. A análise de fragrâncias florais utilizou a técnica de coleta dinâmica combinada com análise via GC-MS. Essa análise confirmou o polimorfismo químico entre as espécies, embora a variabilidade interespecífica tenha sido baixa. Vários dos compostos identificados foram encontrados anteriormente na tíbia traseira de machos de euglossine ou têm sua atratividade conhecida através de estudos com iscas odoríferas. Nossos resultados revelaram ausência de padrão ou tendência evolutiva na composição das fragrâncias das espécies. A pressão seletiva causada pelos polinizadores, ao escolherem as espécies a serem visitadas, tem direcionado a evolução da biologia floral deste gênero. A morfologia, a distribuição do tecido secretor dos osmóforos e a fragrância emitida são complementares, atuando em conjunto para gerar respostas etológicas específicas dos polinizadores. A alta especificidade gerada por este mecanismo reduz o compartilhamento de polinizadores, levando ao transporte mais eficiente do pólen e diminuindo o fluxo gênico interespecífico. / Catasetum is a Netropical genus with ca. 130 species that are practically indistinguishable based on the vegetative morphology. The flowers are primarily unisexual. Male flowers have an exceptional morphological variation and possess modified staminodes as distinctive feature of this genus, which is traditionally cited as entirely pollinated by euglossine bees. The present study evaluated the evolution of the major floral features in Catasetum. To do that, one phylogenetical hypothesis was made using individual and combined matrices of nuclear and plastid DNA. Three regions where sequenced (ITS, rpS16 and trnL-F) for 80 species of Catasetum and 25 taxa of outgroups. The genus is monophyletic and sister to Clowesia in all analyses. Some relationships had high support, however the phylogenetical infrageneric signal was low. None of the traditional infrageneric classifications could be recognized in the phylogeny. From this result, it was possible to observe that the evolutionary history consists on several characters reversions and convergences between species. The plesiomorphic status and some evolutionary trends were recognized. The morpho-anatomy and histochemical analysis of flowers were made with fresh or fixed flowers, whose labellum was sectioned and stained with Lugol 1% and Sudan III or IV, and analyzed with light microscopy. Those analyses reveal a trend to increase labellum complexity in male flowers. It was also possible to observe a direct relation between labellum morphology and distribution of the secretory tissue. The floral scent analysis was made with the dynamic collection technic combined with GC-MS analysis. This analysis confirmed the chemical polymorphism between species, but the interspecific variability was low. Several compounds identified were previously founded in the hind tibiae of male euglossine or have its attractiveness know. Our results revealed an absence of evolution pattern or trend in the scent composition of the species. The selective pressure caused by pollinators, when choosing species to be visited, had guided the evolution of the floral biology of this genus. The morphology, the osmophore secretory tissue distribution and the floral scent are complimentary, acting together to generate specific ethological answers of the pollinators. The high specificity created by this mechanism decrease the sharing of pollinators, leading to a more efficient pollen transport and decreasing the interspecific gene flow.

Catasetum é um gênero Neotropical com cerca de 130 espécies praticamente indistinguíveis quanto à morfologia vegetativa. Suas flores são primariamente unissexuais. As flores masculinas exibem uma excepcional variação morfológica e apresentam estaminódios modificados característicos deste gênero, que é tradicionalmente citado pela polinização exclusiva por abelhas euglossine. Este estudo avaliou a evolução dos principais atributos florais em Catasetum. Para isso, uma hipótese filogenética foi reconstruída utilizando matrizes individuais e combinadas de DNA nuclear e plastidial. Foram sequenciadas três regiões (ITS, rpS16 e trnL-F) para 80 espécies de Catasetum e 25 grupos externos. O gênero é monofilético e irmão de Clowesia em todas as análises. Alguns relacionamentos tiveram alto suporte. Nenhuma das classificações infragenéricas tradicionais pode ser reconhecida na filogenia. A partir deste resultado foi possível observar que a história evolutiva compreendeu várias reversões e convergências de caráter entre as espécies. O estado plesiomórfico e algumas tendências evolutivas são apresentados. As análises morfo-anatômicas e histoquímicas florais utilizaram flores frescas ou fixadas, cujo labelo foi seccionado e corado com Lugol 1% e Vermelho de Sudão III ou IV, sendo examinados através de microscopia de luz. Estas análises revelaram a tendência de aumento na complexidade do labelo apenas em flores masculinas. Também foi possível observar a relação direta entre a morfologia do labelo e a distribuição do tecido secretor. A análise de fragrâncias florais utilizou a técnica de coleta dinâmica combinada com análise via GC-MS. Essa análise confirmou o polimorfismo químico entre as espécies, embora a variabilidade interespecífica tenha sido baixa. Vários dos compostos identificados foram encontrados anteriormente na tíbia traseira de machos de euglossine ou têm sua atratividade conhecida através de estudos com iscas odoríferas. Nossos resultados revelaram ausência de padrão ou tendência evolutiva na composição das fragrâncias das espécies. A pressão seletiva causada pelos polinizadores, ao escolherem as espécies a serem visitadas, tem direcionado a evolução da biologia floral deste gênero. A morfologia, a distribuição do tecido secretor dos osmóforos e a fragrância emitida são complementares, atuando em conjunto para gerar respostas etológicas específicas dos polinizadores. A alta especificidade gerada por este mecanismo reduz o compartilhamento de polinizadores, levando ao transporte mais eficiente do pólen e diminuindo o fluxo gênico interespecífico. / Catasetum is a Netropical genus with ca. 130 species that are practically indistinguishable based on the vegetative morphology. The flowers are primarily unisexual. Male flowers have an exceptional morphological variation and possess modified staminodes as distinctive feature of this genus, which is traditionally cited as entirely pollinated by euglossine bees. The present study evaluated the evolution of the major floral features in Catasetum. To do that, one phylogenetical hypothesis was made using individual and combined matrices of nuclear and plastid DNA. Three regions where sequenced (ITS, rpS16 and trnL-F) for 80 species of Catasetum and 25 taxa of outgroups. The genus is monophyletic and sister to Clowesia in all analyses. Some relationships had high support, however the phylogenetical infrageneric signal was low. None of the traditional infrageneric classifications could be recognized in the phylogeny. From this result, it was possible to observe that the evolutionary history consists on several characters reversions and convergences between species. The plesiomorphic status and some evolutionary trends were recognized. The morpho-anatomy and histochemical analysis of flowers were made with fresh or fixed flowers, whose labellum was sectioned and stained with Lugol 1% and Sudan III or IV, and analyzed with light microscopy. Those analyses reveal a trend to increase labellum complexity in male flowers. It was also possible to observe a direct relation between labellum morphology and distribution of the secretory tissue. The floral scent analysis was made with the dynamic collection technic combined with GC-MS analysis. This analysis confirmed the chemical polymorphism between species, but the interspecific variability was low. Several compounds identified were previously founded in the hind tibiae of male euglossine or have its attractiveness know. Our results revealed an absence of evolution pattern or trend in the scent composition of the species. The selective pressure caused by pollinators, when choosing species to be visited, had guided the evolution of the floral biology of this genus. The morphology, the osmophore secretory tissue distribution and the floral scent are complimentary, acting together to generate specific ethological answers of the pollinators. The high specificity created by this mechanism decrease the sharing of pollinators, leading to a more efficient pollen transport and decreasing the interspecific gene flow.