The evolution of wind pollination (anemophily) has occurred at least 65 times in the flowering plants and over 10% of angiosperm species are wind pollinated. However the pollination and mating of anemophily species is poorly understood, particularly in comparison with animal-pollinated species. My thesis employs a range of approaches and tools to examine the evolution and ecology of wind pollination. These include comparative analyses, theoretical modeling, field and glasshouse experiments, the use of genetic markers and quantitative genetics. Experimental studies on diverse taxa were used to address questions concerned with the efficacy of outcrossing mechanisms, the ecological and demographic context of pollination and mating, and the plasticity of sex allocation. Comparative analyses indicated that wind pollination is correlated with unisexual flowers, reduced ovule number, small unshowy flowers, an absence of nectar, and open habitats. These analyses also demonstrated that anemophily originates more often in lineages with unisexual flowers. This suggests that wind pollination evolves in diclinous taxa as a mechanism of reproductive assurance because autonomous selfing is mechanically precluded. Empirical data on stigmatic pollen loads in 19 anemophilous species challenge the widespread assumption that anemophilous plants commonly have uniovulate flowers because they capture few pollen grains. Further, a model based on floral costs and the aerodynamics of pollen capture demonstrated that when flowers are inexpensive it is optimal to produce many flowers each with few ovules, because this allows more efficient sampling of the airstream. Manipulative field experiments on seven Carex species indicated that neither monoecy nor protogyny, two putative outcrossing mechanisms, are effective at limiting selfing. Based on these results I suggest that geitonogamy can provide reproductive assurance in anemophilous species with unisexual flowers. Field experiments and the application of sex-specific markers in Rumex nivalis revealed that the local neighbourhood of maternal plants affects pollination intensity and progeny sex ratios. Finally, I demonstrated that plant density in Ambrosia artemisiifolia affects stigmatic pollen loads but not outcrossing rates. Through a quantitative genetics experiment in A. artemisiifolia, I detected significant genetic variation for plasticity in sex allocation, potentially enabling adaptive adjustment of sex allocation to local environmental conditions.

The evolution of wind pollination (anemophily) has occurred at least 65 times in the flowering plants and over 10% of angiosperm species are wind pollinated. However the pollination and mating of anemophily species is poorly understood, particularly in comparison with animal-pollinated species. My thesis employs a range of approaches and tools to examine the evolution and ecology of wind pollination. These include comparative analyses, theoretical modeling, field and glasshouse experiments, the use of genetic markers and quantitative genetics. Experimental studies on diverse taxa were used to address questions concerned with the efficacy of outcrossing mechanisms, the ecological and demographic context of pollination and mating, and the plasticity of sex allocation. Comparative analyses indicated that wind pollination is correlated with unisexual flowers, reduced ovule number, small unshowy flowers, an absence of nectar, and open habitats. These analyses also demonstrated that anemophily originates more often in lineages with unisexual flowers. This suggests that wind pollination evolves in diclinous taxa as a mechanism of reproductive assurance because autonomous selfing is mechanically precluded. Empirical data on stigmatic pollen loads in 19 anemophilous species challenge the widespread assumption that anemophilous plants commonly have uniovulate flowers because they capture few pollen grains. Further, a model based on floral costs and the aerodynamics of pollen capture demonstrated that when flowers are inexpensive it is optimal to produce many flowers each with few ovules, because this allows more efficient sampling of the airstream. Manipulative field experiments on seven Carex species indicated that neither monoecy nor protogyny, two putative outcrossing mechanisms, are effective at limiting selfing. Based on these results I suggest that geitonogamy can provide reproductive assurance in anemophilous species with unisexual flowers. Field experiments and the application of sex-specific markers in Rumex nivalis revealed that the local neighbourhood of maternal plants affects pollination intensity and progeny sex ratios. Finally, I demonstrated that plant density in Ambrosia artemisiifolia affects stigmatic pollen loads but not outcrossing rates. Through a quantitative genetics experiment in A. artemisiifolia, I detected significant genetic variation for plasticity in sex allocation, potentially enabling adaptive adjustment of sex allocation to local environmental conditions.

Premise of The Study: Studies on the effects of heterospecific pollen (HP) transfer have been focused mainly on insect-pollinated species, despite evidence of insect visitation to wind-pollinated species and transfer of their pollen onto stigmas of insect-pollinated plants. Thus, the potential consequences of HP transfer from wind-pollinated species remain largely unknown. Furthermore, accumulation of pesticide residues in pollen of wind-pollinated crops has been documented, but its potential effects on wild plant species via HP transfer have not been tested. Methods: We evaluated the effect of wind-dispersed Zea mays pollen on pollen tube growth of the insect-pollinated Mimulus nudatus via hand pollinations. We further evaluated whether pesticide-contaminated Z. mays pollen has larger effects on M. nudatus pollen success than non-contaminated Z. mays pollen. Key Results: We found a significant negative effect of Z. mays pollen on M. nudatus pollen tube growth even when deposited in small amounts. However, we did not observe any difference in the magnitude of this effect between pesticide-laden Z. mays pollen and non-contaminated Z. mays pollen. Conclusions: Our results suggest that wind-pollinated species can have negative effects as HP donors on insect-pollinated recipients. Thus, their role in shaping co-flowering interactions for wind- and insect-pollinated species deserves more attention. Although we did not find evidence that pesticide contamination increased HP effects, we cannot fully rule out the existence of such an effect, because pollen load and thus the pesticide dose applied to stigmas was low. This result should be confirmed using other HP donors and across a range of HP loads, pesticide types, and concentrations.

No description available.

<p>In this thesis, I examined variation in sex expression and mating patterns in the sexually polymorphic, wind-pollinated herb <i>Plantago maritima</i>. With a combination of field studies, greenhouse experiments, and genetic analyses, I (a) examined factors influencing sex ratio variation in gynodioecious plants (in which hermaphrodites and females coexist), (b) discovered variation in breeding system, (c) investigated density-dependence of seed production, and (d) documented genetic variation within and among populations close to the northern range margin in Europe. </p><p>In a survey of 104 <i>P. maritima</i> populations, I documented considerable variation in sex ratio (range 0-70% females, median 6.3% females). As predicted, females were more frequently missing from small than from large populations, and the variance in sex ratio increased with decreasing population size. Among twelve populations sampled for seed production, the frequency of females was positively related to relative fecundity of females and negatively related to population size. The results suggest that the local sex ratio is influenced both by the relative fecundity of females and hermaphrodites, and by stochastic processes in small populations.</p><p>A comparative field study showed that plant fecundity decreased with increasing distance to nearest pollen donor both within and among populations in an archipelago in southern Sweden, where self-incompatibility was confirmed in controlled crosses. In contrast, plant fecundity was overall higher and was not density-dependent in the Skeppsvik archipelago in northern Sweden, where controlled crosses showed that plants are self-compatible. The results were consistent with the prediction that evolution of self-fertility should reduce density-dependence of pollination success.</p><p>I quantified the genetic structure within and among populations from eastern Sweden and western Finland based on variation at four polymorphic microsatellite loci. The genetic diversity was low in northern Sweden, which may be the result of a history of small population sizes and periods of frequent self-fertilization.</p>

In this thesis, I examined variation in sex expression and mating patterns in the sexually polymorphic, wind-pollinated herb Plantago maritima. With a combination of field studies, greenhouse experiments, and genetic analyses, I (a) examined factors influencing sex ratio variation in gynodioecious plants (in which hermaphrodites and females coexist), (b) discovered variation in breeding system, (c) investigated density-dependence of seed production, and (d) documented genetic variation within and among populations close to the northern range margin in Europe. In a survey of 104 P. maritima populations, I documented considerable variation in sex ratio (range 0-70% females, median 6.3% females). As predicted, females were more frequently missing from small than from large populations, and the variance in sex ratio increased with decreasing population size. Among twelve populations sampled for seed production, the frequency of females was positively related to relative fecundity of females and negatively related to population size. The results suggest that the local sex ratio is influenced both by the relative fecundity of females and hermaphrodites, and by stochastic processes in small populations. A comparative field study showed that plant fecundity decreased with increasing distance to nearest pollen donor both within and among populations in an archipelago in southern Sweden, where self-incompatibility was confirmed in controlled crosses. In contrast, plant fecundity was overall higher and was not density-dependent in the Skeppsvik archipelago in northern Sweden, where controlled crosses showed that plants are self-compatible. The results were consistent with the prediction that evolution of self-fertility should reduce density-dependence of pollination success. I quantified the genetic structure within and among populations from eastern Sweden and western Finland based on variation at four polymorphic microsatellite loci. The genetic diversity was low in northern Sweden, which may be the result of a history of small population sizes and periods of frequent self-fertilization.

Thesis (Ph. D.)--Miami University, Dept. of Botany, 2006. / Title from second page of PDF document. Includes bibliographical references.

Made available in DSpace on 2016-12-12T20:12:31Z (GMT). No. of bitstreams: 1 PGEF14MA023.pdf: 1162043 bytes, checksum: 8432963324a52811e61e2d071eacc033 (MD5) Previous issue date: 2014-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Gene flow is a determining component of persistence and adaptation of local populations, and may influence their ecological properties. Understand the behavior of this flow in natural or altered populations is essential for developing effective conservation plans by the use of natural resources. We investigated the influence of Pinus plantations in the pollen dispersal patterns in remaining Araucaria angustifolia populations (patches), using paternity analysis with eight microsatellite locos. For this, we sampled two patches in the grassland area and two patches in the pine plantations area, located in southern Santa Catarina plateau. In the study areas all male reproductive individuals (68) and 400 seeds from 20 seed-tree (five per population) were mapped and genotyped. The paternity analysis revealed higher average distance of pollination for grassland area (170 m) than Pinus plantation area (67 m). The effective number of pollen donors (Nep) was 16.4 and 8.9 for grassland area and Pinus, respectively. Grassland areas showed a pollen immigration rate of 46%, and the plantation area showed a 36%. These results are an indication that the Pinus plantation can act as barrier to pollen flow, although, pollen dispersal occurs through plantings. There was no significant spatial genetic structure for adults, and high levels of genetic diversity were verified in both areas (He, ranging 0.16 to 0.829), with no significant differences, suggesting presence of historic gene flow between locals. While the seeds from natural grasslands seed-tree present no significant fixation index, the seeds from seed-tree located into Piuns plantations presented significant fixation indexes (F = 0.076, P<0.05). Both adult population and seeds showed private alleles, evidencing that not all possible reproductive individuals, in the remnants, contributed to seed sampled formation, however, pollen flow from outside contributed effectively to seed formation within patches / O fluxo gênico é um dos componentes determinantes da persistência e adaptação das populações locais, podendo influenciar em suas propriedades ecológicas. Entender o comportamento desse fluxo em populações naturais ou alteradas é essencial para elaboração de planos eficazes de conservação pelo uso dos recursos naturais. Investigou-se a influência de plantios de Pinus no padrão de dispersão de pólen em populações remanescentes de Araucaria angustifolia (capões), por meio análises de paternidade com oito locos microssatélites. Para isso, amostraram-se dois capões em área de campo e dois em área de plantios de Pinus, localizados no planalto sul catarinense. Nas áreas de estudo (capões) foram mapeados e genotipados todos os 68 indivíduos machos reprodutivos e mais 400 sementes retiradas de 20 plantas matrizes (cinco por população). A análise de paternidade revelou que a distância média de polinização para a área de campo (170 m), foi maior do que para área de plantios de Pinus (67 m). O número efetivo de polinizadores (Nep) foi de 16,4 e 8,9 para área de campo e plantio de Pinus, respectivamente. Áreas de campo apresentaram uma taxa de imigração de pólen de 46% e áreas de plantio apresentaram 36%. Esses resultados são um indicio de que os plantios de Pinus podem agir como barreira ao fluxo de pólen, embora ainda ocorre fluxo através dos plantios. Verificou-se a presença de estrutura genética espacial não significativa para os indivíduos adultos em ambas as áreas, além de uma elevada diversidade genética (He, variando de 0,16 a 0,829), sem diferenças significativas, sugerindo a presença de um fluxo gênico histórico entre as áreas. Enquanto as sementes oriundas das matrizes em meio as áreas de campo não apresentaram índice de fixação significativos, as sementes oriundas das árvores em meio aos plantios de Pinus apresentarem índices de fixação significativos (F = 0,076, P<0,05). Tanto a população adulta quanto as sementes apresentaram alelos exclusivos, evidenciando que nem todos os indivíduos reprodutivos presentes nos remanescentes contribuíram para a formação da amostra de sementes, entretanto o fluxo de pólen externo contribuiu efetivamente para formação das sementes de dentro do capão