Studies assessing the evolution of plant traits frequently focus on pollinators as the primary drivers of floral trait evolution. However, herbivores can also play a role, and, under some circumstances, may even impose stronger selection on floral display than pollinators. This is especially true when the traits under selection are linked to anti-herbivore defense. Here I describe a study in which I quantified the relative role of herbivores and pollinators in selection for floral traits in the North American invasive plant, purple loosestrife (Lythrum salicaria). Because L. salicaria responds to leaf-chewing herbivores by producing compensatory tissue growth, and this in turn alters the architecture of the floral display, I further tested whether herbivores can indirectly modify pollinator-mediated selection through this pathway. Using a split-plot design, I measured pollen limitation and reproductive output in experimentally manipulated plants in the presence and absence of simulated herbivore damage in order to quantify the effects of damage and pollination on natural selection for floral display. My results showed that damage significantly increased direct selection (beta-i) for earlier flowering time and decreased selection on the number of inflorescences, even more than pollinators did. Because damage did not modify pollinator-mediated selection for floral display traits, the selection imposed by herbivores is likely only having direct effects. My findings demonstrate the importance of considering multiple agents of selection and their potential interactions when quantifying natural selection in a study system. In particular, it is important to consider that the agent most frequently studied may not be imposing the brunt of selection.

Repeated polyploidization events are thought to be among the most important causes of sympatric speciation throughout evolutionary time. Changes in phenology and trait expressions that arise in polyploids have been shown to affect plant interactions with insect herbivores and pollinators. If these interactions are changed, selection subsequent to the polyploidization event could contribute to further divergence, or increased similarity, of cytotypes. This study was conducted to investigate plant interactions with insect herbivores and pollinators and patterns of selection in tetraploid and octoploid Cardamine pratensis L. (Brassicaceae), and to answer the following questions: i) Is there phenotypic selection on flowering phenology and number of flowers? ii) Is pollen limitation or herbivory most important for variation in reproductive output? iii) During what stages of ovary and ovule development do variation in fitness mainly arise? iv) Can the intensity of interactions be linked to phenology and number of flowers, suggesting that selection is mediated by pollen limitation or herbivory? v) Do intensity of interactions, and of interaction-mediated selection, differ between ploidy levels? From a combination of an observational study of herbivory and a hand pollination experiment, selection was found for earlier flowering in both subspecies. Intensity of herbivory was an important determinant of plant reproductive success, while hand pollination had little effect. Positive effects of flowering time on intensity of herbivory suggest that selection for earlier flowering was mediated by herbivores. Tetraploids initiated flowering later and suffered from more intense herbivory than did octoploids. The direction of selection was similar in both subspecies. However, differences strength of selection and intensity of herbivory suggest that there is a possibility of selection for their further divergence. / Polyploidisering anses vara en av de viktigaste orsakerna till artbildning inom populationer. Skillnader i blomningskaraktärer, såsom fenologi och blomantal, som uppstår i och med polyploidiseringen har visat sig påverka växters interaktioner med såväl pollinatörer som herbivorer. Förändringar i växt-insektsinteraktioner till följd av polyploidiseringen kan leda till selektion för ökade skillnader, eller likheter, mellan cytotyper. Studiens syfte var att undersöka växters interaktioner med insekter i form av pollinatörer och herbivorer, samt att undersöka selektionsmönster hos tetraploida och oktoploida Cardamine pratensis L. (Brassicaceae). Jag ville även besvara följande frågor: i) Sker selektion på blomningstid och blomantal? ii) Vilken växt-insektsinteraktion är viktigast för variation i reproduktionsframgång? iii) Under vilka utvecklingsstadier uppstår den största variationen i fitness? iv) Kan intensiteten av interaktionerna kopplas till blomningsfenologi och blomantal, vilket skulle indikera att selektion förmedlas genom pollenbegränsning eller herbivori? v) Skiljer sig styrkan av interaktionerna, och av interaktionsförmedlad selektion, mellan ploidinivåer? Studien utformades som en kombination av en observationsstudie av herbivori och ett handpollineringsexperiment, och jag fann selektion för tidigare blomning hos de två underarterna. Reproduktionsframgång styrdes av herbivori snarare än pollenbegränsing. Förlust av potentiell fitness genom att fröämnen inte utvecklades till frön var den faktor som starkast påverkade variation i fitness, och detta var också den fas i utvecklingen som bidrog i störst utsträckning till kvantitativ förlust av fitness. Ett positivt samband mellan blomningsfenologi och herbivoriintensitet indikerar att selektion för blomningstid var förmedlad av herbivorer. Tetraploider blommade senare och utsattes för mer intensiva herbivorattacker än oktoploider. Detta, samt skillnader i selektionsstyrka, indikerar att selektion skulle kunna leda till ökad divergens av underarterna.

© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust The role of pollination in the success of invasive plants needs to be understood because invasives have substantial effects on species interactions and ecosystem functions. Previous research has shown both that reproduction of invasive plants is often pollen limited and that invasive plants can have high seed production, motivating the questions: How do invasive populations maintain reproductive success in spite of pollen limitation? What species traits moderate pollen limitation for invaders? We conducted a phylogenetic meta-analysis with 68 invasive, 50 introduced noninvasive and 1931 native plant populations, across 1249 species. We found that invasive populations with generalist pollination or pollinator dependence were less pollen limited than natives, but invasives and introduced noninvasives did not differ. Invasive species produced 3× fewer ovules/flower and >250× more flowers per plant, compared with their native relatives. While these traits were negatively correlated, consistent with a tradeoff, this did not differ with invasion status. Invasive plants that produce many flowers and have floral generalisation are able to compensate for or avoid pollen limitation, potentially helping to explain the invaders’ reproductive successes.

in English Montane conditions represent a relatively unfavorable climate for most plants and their pollinators. Consequently, zoogamous plant species growing at high elevations are expected to be pollen limited. According to the "reproductive assurance" and "transmission advantage" hypotheses, such pollen-limited plants will adapt more toward self-pollination than plants in communities with more reliable pollination. To test such predictions, I studied reproduction strategies and pollen limitation of ten zoogamous plant species at three elevations (2,800 m a.s.l. 3,500 m a.s.l. and 4,000 m a.s.l.) in montane grasslands on Mount Cameroon, West/Central Africa. I compared seed sets produces by plants with four treatments in our extensive hand-pollination experiments: autogamy, geitonogamy, outcrossing, and natural control. One experimental species was found to be self-incompatible, six species were partially self-compatible, and one was completely self-compatible and predominantly selfing. In five of these plant species, I compared the reproduction strategies and pollen limitation among the elevations. I found that pollen limitation did rise in two species, we expect this to be due to the fact that the species were already pollen limited at 2,800 m a.s.l. Contrary to the two hypotheses, selfing did...

No description available.

Pollination success of animal-pollinated flowers depends on rate of pollinator visits and on pollen deposition per visit, both of which should vary with the pollen and nectar "neighborhoods" of a plant, i.e., with pollen and nectar availability in nearby plants. One determinant of these neighborhoods is per-flower production of pollen and nectar, which is likely to respond to environmental influences. In this study, we explored environmental effects on pollen and nectar production and on pollination success in order to follow up a surprising result from a previous study: flowers of Ipomopsis aggregata received less pollen in years of high visitation by their hummingbird pollinators. A new analysis of the earlier data indicated that high bird visitation corresponded to drought years. We hypothesized that drought might contribute to the enigmatic prior result if it decreases both nectar and pollen production: in dry years, low nectar availability could cause hummingbirds to visit flowers at a higher rate, and low pollen availability could cause them to deposit less pollen per visit. A greenhouse experiment demonstrated that drought does reduce both pollen and nectar production by I. aggregata flowers. This result was corroborated across 6 yr of variable precipitation and soil moisture in four unmanipulated field populations. In addition, experimental removal of pollen from flowers reduced the pollen received by nearby flowers. We conclude that there is much to learn about how abiotic and biotic environmental drivers jointly affect pollen and nectar production and availability, and how this contributes to pollen and nectar neighborhoods and thus influences pollination success.

Understanding how floral traits covary with one another and with mating patterns is an important step in understanding how and why mating systems evolve. I examined the evolution of floral and mating system variation in Camissoniopsis cheiranthifolia (Onagraceae), a species that exhibits divergence in key floral traits expected to be associated with variation in the relative importance of outcrossing vs. self-fertilization. I combined geographic surveys of floral variation with genetic estimates of the proportion of seeds outcrossed (t) and confirmed that t covaried with corolla width and herkogamy in a predictable way both within and among populations. I then performed geographic surveys, manipulative experiments and genetic analyses to evaluate the potential role that; inbreeding depression (ID), interactions between flowers, pollinators and florivores, and reproductive assurance (RA) may have played in shaping and/or maintaining the geographic pattern of mating system variation in this species. The main selective factor maintaining outcrossing in large flowered (LF) populations appears to be ID, which was much stronger in LF compared to small flowered (SF) populations. These results are also consistent with purging of ID in SF populations. Increased selfing appeared to alleviate pollen limitation (PL) because it was associated with higher and less variable fruit set and reduced florivory by a microlepidopteran. However, evidence that florivores preferentially attacked larger flowers was equivocal. LF experienced stronger PL than SF populations suggesting that one condition for the evolution of selfing via RA is met in outcrossing populations. Floral emasculation experiments revealed that the timing of selfing also covaried with flower size among and within populations. SF self-pollinate before flowers open but LF do not, suggesting that selfing evolved in response to chronic outcross PL. Negative side effects of emasculation were detected which prevented a clear interpretation of the RA value of selfing. Given that much of what is known about RA comes from emasculation experiments, my results suggest that the assumptions of this approach, which are rarely verified, require more serious consideration. Taken together my results suggest that C. cheiranthifolia has evolved multiple stable mixed mating systems perhaps in response to selection for RA. / Thesis (Ph.D, Biology) -- Queen's University, 2012-12-30 14:13:46.366

The aim of this thesis was to study patterns of reproduction of Betula pendula and B. pubescens coll. along an altitudinal, coastal-inland, gradient in northern Sweden. The altitudinal variation was related to the distribution of the birch taxa along the gradient. Six years field data showed a steep decrease of seed germinability of B. pendula towards its altitudinal range limit in the Scandes every year. In contrast, B. pubescens ssp. pubescens showed significant positive correlations between seed germinability and altitude in three of the six years. Furthermore, there was a highly significant positive correlation between seed weight and altitude for B. pubescens coll., but not for B. pendula. Production of viable seeds fluctuated strongly between years in most populations, except in marginal B. pendula populations in the mountain area where it was constantly very low. On average 15 - 41 % of the seeds produced in B. pendula populations above 400 m altitude were attacked by gall midges (Semudobia ssp.). Corresponding values for B. pendula populations below 400 m altitude were 4 - 7 %. In B. pubescens populations, the seeds attacked by Semudobia ssp. never exceeded 3 %. The high frequency of Semudobia attackes in high altitude marginal B. pendula populations was suggested to be due to limited resources for defense against the seed predator. A 3-yr study documented large variations in pollination and seed quality between taxa, high and low altitude populations, and between years. Empty seeds (without embryos) dominated among the sampled seeds in most cases. This proportion was decreased by pollen addition, in both B. pendula and B. pubescens, in mountain populations, but not in coastal populations. The high percentage of empty seeds was therefore suggested to be partly caused by pollen-limitation, but failure of pollen tube penetration - fertilisation, or maternal resource supply could also have had an influence. A laboratory experiment showed increased pollen germination and length of the longest pollen tube per style after increased pollination. The correlations between number and length of pollen tubes per style were however mostly low in natural populations, suggesting low probability of pollen competition in the natural situation. Sowing experiments indicated that differences in initial seedling density between B. pendula and B. pubescens was more affected by interspecific differences in seed quality than by interspecific differences in survival of seedlings after establishment A study of the age structure of a B. pendula stand, planted about 250 m above its natural altitudinal limit, indicated that this birch may reproduce above its recent range limit during temporally warmer periods. It was concluded that the level of accumulated resources in B. pendula in marginal sites in the Scandes would mostly be too low for completion of the reproductive cycle. In contrast, B. pubescens ssp. pubescens is able to accumulate enough rescources for reproduction also at relative high altitudes. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 5 uppsatser.</p> / digitalisering@umu

Submitted by Luciana Sebin (lusebin@ufscar.br) on 2016-10-06T12:39:19Z No. of bitstreams: 1 DissNSM.pdf: 1899141 bytes, checksum: af65acf968d8fc129372f4131e0a5ce2 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-13T20:21:59Z (GMT) No. of bitstreams: 1 DissNSM.pdf: 1899141 bytes, checksum: af65acf968d8fc129372f4131e0a5ce2 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-13T20:22:10Z (GMT) No. of bitstreams: 1 DissNSM.pdf: 1899141 bytes, checksum: af65acf968d8fc129372f4131e0a5ce2 (MD5) / Made available in DSpace on 2016-10-13T20:22:21Z (GMT). No. of bitstreams: 1 DissNSM.pdf: 1899141 bytes, checksum: af65acf968d8fc129372f4131e0a5ce2 (MD5) Previous issue date: 2016-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Pollination is an effective ecosystem service, responsible for increasing the quantity and quality of fruits and seeds formed. Due to the self-incompatibility of some species of agricultural interest, cross-pollination is required and the limiting of pollinating species such affects its production. The yellow passion fruit (Passiflora edulis f. flavicarpa.), a selfincompatible specie is dependent on cross-pollination to form fruit. Thus, the general aim of this study was to study the biology of pollination and reproduction in P. edulis f. flavicarpa, emphasizing the efficacy of pollinators for this specie. The specific aims were: 1) to evaluate the richness, visitation frequency and the behavior of visitors in Passiflora edulis f. flavicarpa flowers.; 2) to compare the efficacy in the formation of fruits and seeds of P. edulis f. flavicarpa through individual and two visits by Xylocopa frontalis with manual crosspollination and natural pollination and 3) assess whether there is pollen limitation through comparison between natural and manual cross-pollination. Visitors were observed during the flowering period, from January to April 2015, totaling 106 hours of observations. For fruiting testing and seed counts: 1) manual cross pollination (n = 37 flowers); 2) natural pollination (n = 52 flowers); 3) pollination by single visit of X. frontalis (n = 41 flowers) and 4) pollination by two visits of X. frontalis. Were identified bee species of Apis, Bombus, Centris, Epicharis, Eulaema, Melipona, Oxaea, Trigona and Xylocopa genera, Apidae, being also observed an individual belonging to Halictidae family. Insects belonging to other orders were also observed, including different species of butterflies (Lepidoptera), bugs (Hemiptera), flies (Diptera), beetles (Coleoptera) and the presence of family Trochilidae hummingbirds. The specie A. mellifera (thief behavior) and X. frontalis (predominantly pollinator behavior) were the most frequent in the plantation with 58.11% and 30.20% respectively of occurrence. Regarding pollination tests, we observed the formation of fruits in all the treatments. Flowers of manual cross-pollination obtained the highest fruiting rate when compared to other treatments. The fruiting rate through manual cross-pollination was significantly higher than that obtained in natural conditions (X2 = 12.676; degree of freedom = 1; p <0.05) indicating that there is pollen limitation in natural pollination. Regarding the number of seeds, an analysis of variance (ANOVA) indicated no significant difference between the mean number of seeds produced in different reviews pollination. Conclude that there is richness of floral visitors specie in the study area, and that between them, the main pollinator species are those with larger, mainly bees belonging to the genus Xylocopa. Larger fruiting rates obtained by manual cross-pollination treatment suggest that more than one visit is needed to promote greater production rate in passion fruit crops. / A polinização é um serviço ecossistêmico, responsável por aumentar a quantidade e a qualidade dos frutos e sementes formados. Devido à autoincompatibilidade de algumas espécies de interesse agrícola, a polinização cruzada torna-se necessária e a limitação de polinizadores nessas espécies afeta a sua produção. O maracujá-amarelo (Passiflora edulis f. flavicarpa Deg.), por ser uma espécie autoincompatível, é dependente da polinização cruzada para a formação de seus frutos. Dessa forma, o objetivo geral desse estudo foi estudar a biologia da polinização e a reprodução de P. edulis f. flavicarpa, enfatizando a eficácia do principal polinizador dessa espécie. Os objetivos específicos foram: 1) avaliar a riqueza, frequência de visitas e o comportamento dos visitantes em flores de Passiflora edulis f. flavicarpa Deg.; 2) comparar a eficácia na formação de frutos e sementes em P. edulis f. flavicarpa por meio de visitas individuais e duas visitas de Xylocopa frontalis com a polinização cruzada manual e a polinização natural e 3) avaliar se há limitação polínica por meio da comparação entre a polinização cruzada manual e a polinização natural. Os visitantes florais foram observados durante o período de floração, de janeiro a abril de 2015, totalizando 106 horas de observações. Para avaliar a eficácia da polinização e a limitação polínica foram realizados quatro tratamentos distintos de polinização: 1) Polinização cruzada manual (n=37 flores); 2) Polinização natural (n=52 flores); 3) Uma visita de X. frontalis (n=41 flores) e 4) Duas visitas de X. frontalis (n=31 flores). Para cada tratamento foi avaliado a formação de frutos e a produção de sementes. Foram identificadas espécies de abelhas dos gêneros Apis, Bombus, Centris, Epicharis, Eulaema, Melipona, Oxaea, Trigona e Xylocopa (Apidae), sendo também observado um indivíduo pertencente a família Halictidae. Insetos pertencentes a outras ordens também foram observados, entre eles, diferentes espécies de borboletas (Lepidoptera), percevejos (Hemiptera), moscas (Diptera), besouros (Coleoptera) e a presença de beija-flores da família Trochilidae. As espécies A. mellifera (comportamento pilhador) e X. frontalis (comportamento predominantemente polinizador) foram as mais frequentes na plantação com 58,11% e 30,20% das visitas respectivamente. Em relação aos tratamentos de polinização, verificamos que houve formação de frutos em todos os tratamentos realizados. Flores de polinização cruzada manual obtiverem a maior taxa de frutificação quando comparada aos demais tratamentos. A taxa de frutificação por meio da polinização cruzada manual foi significativamente maior que a obtida em condições naturais (X2 = 12,676; grau de liberdade = 1; p<0,05) indicando que há limitação polínica na polinização natural. Em relação à quantidade de sementes, a análise de variância (ANOVA) não indicou diferença significativa entre as médias do número de sementes produzidas nos diferentes tratamentos. Concluímos que há riqueza de espécies visitantes florais na área estudada, e que entre elas, as principais espécies polinizadoras são aqueles que possuem maior tamanho, principalmente as abelhas do gênero Xylocopa. Maiores taxas de frutificação obtidas por meio do tratamento de polinização cruzada manual sugerem que mais de uma visita é necessária para aumentar a produtividade.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O estudo da ecologia floral à fundamental para o entendimento das relaÃÃes entre flores e seus visitantes, assim como para entender o papel dessa interaÃÃo no sucesso reprodutivo e na manutenÃÃo da populaÃÃo vegetal. No presente estudo, investigou-se a morfologia, a biologia floral e o sistema de reproduÃÃo de Ipomoea bahiensis Willd., bem como as interaÃÃes entre suas flores e a guilda de visitantes florais. A investigaÃÃo teve como objetivo central entender tanto as relaÃÃes ecolÃgicas e evolutivas entre I. bahiensis e insetos antÃfilos quanto o sistema reprodutivo da planta. Para tanto, foram empregados mÃtodos para analisar a morfologia funcional das flores, a relaÃÃo da morfologia e biologia floral com os visitantes, o comportamento e frequÃncia desses animais, o requerimento polÃnico e a relaÃÃo fruto/flor e, por fim, foi quantificada a limitaÃÃo de pÃlen. Para incrementar o conhecimento sobre a ecologia floral, foram observados os visitantes de nectÃrios extranupciais e sua relaÃÃo com inimigos florais. A partir da anÃlise dos dados obtidos, observou-se que as flores de I. bahiensis possuem atributos predominantemente de psicofilia, contudo tÃm plasticidade no sistemas de polinizaÃÃo, podendo ser polinizadas por abelhas de pequeno porte. A dinÃmica do nÃctar juntamente com o perÃodo de receptividade do estigma procura, possivelmente, garantir a visitaÃÃo de borboletas nesse perÃodo. No entanto, a variaÃÃo na frequÃncia dos visitantes florais foi entendida a partir da disponibilidade de pÃlen, pois os principais visitantes foram abelhas coletoras de pÃlen. Os testes de polinizaÃÃo mostraram que o sistema de reproduÃÃo à xenÃgamo, dependente de vetores biÃticos e apresenta auto-incompatibilidade. TambÃm foi observado que a planta à limitada por pÃlen / The study of floral ecology is pivotal to understanding the relationships between flowers and their visitors, as well as to understand the role of this interaction in reproductive success and maintenance of plant population. In this study, it was investigated the morphology, floral biology and breeding system of Ipomoea bahiensis Willd. and the interactions between its flowers and the guild of floral visitors. The research aimed mainly to understand the ecological and evolutionary relationships between I. bahiensis and anthophilous insects. For this, methods were used to analyze the functional morphology of flowers, the relationship of floral morphology and biology with visitors, the frequency and behavior these animals, the requirement for pollen and the rate fruit/flower and, finally, was estimated pollen limitation. To increase knowledge about the floral ecology were observed extranupcial nectariesâs visitors and its relation to floral enemies. From the analysis of the data, it was observed that the flowers of I. bahiensis have attributes predominantly psycophily, however they present plasticity in pollination systems, and can also be pollinated by small bees. The dynamics of nectar herewith with the period of stigma receptivity seeks to ensure the visitation of butterflies in this period. However, the variation in the frequency of floral visitors was understood from the availability of pollen, because the main visitors were bees pollen collecting. Pollination tests showed that the reproductive system is xenogamous, dependent on biotic vectors and presents self-incompatibility. It was also observed that the plant is limited by pollen