Les plantes n'exploitent pas seules les nutriments du sol, mais dépendent de champignons avec lesquels elles forment des symbioses mycorhiziennes dans leurs racines. C'est en particulier vrai pour les 25 000 espèces d'orchidées actuelles qui dépendent toutes de champignons mycorhiziens pour accomplir leur cycle de vie. Elles produisent des graines microscopiques qui n'ont pas les ressources nutritives pour germer, mais qui dépendent de la présence de partenaires adéquats pour nourrir l'embryon (hétérotrophie) jusqu'à l'apparition des feuilles (autotrophie). Les mycorhiziens restent présents dans les racines des adultes où ils contribuent à la nutrition, ce qui permet d'étudier plus facilement la diversité des symbiotes à l'aide des outils génétiques. Conscients des biais des études en faveur des régions tempérées, nous avons étudié la diversité des mycorhiziens d'orchidées tropicales à La Réunion. Nous avons montré que (1) les orchidées tropicales ont des partenaires semblables aux orchidées tempérées et méditerranéennes (Sebacinales, Ceratobasidiaceae et surtout Tulasnellaceae), et que ces taxons de champignons sont largement représentés dans différents biomes et dans différentes plantes hôtes. Nous avons aussi démontré pour la première fois que (2) les orchidées épiphytes (dont les associations étaient peu connues) ont des cortèges mycorhiziens différents de ceux des orchidées terrestres dans les communautés tropicales. De plus, en développant une approche à l'échelle de réseaux d'interactions (78 espèces de La Réunion), nous avons montré que (3) les espèces tropicales ont tendance à être généralistes et que (4) le réseau mycorhizien des orchidées montre des propriétés semblables à celles des réseaux d'interactions mutualistes (nestedness et asymétrie d'interaction), alors que la nature mutualiste de cette symbiose mycorhiziennes fait débat. Dans un second volet de la thèse, nous avons étudié les partenaires des orchidées non chlorophylliennes (mycohétérotrophes) tropicales. Nous avons montré que (5) les espèces tropicales peuvent s'associer à des champignons saprophytes qui les nourrissent en carbone issu de la décomposition de la litière dans les forêts tropicales humides et que (6) les modèles tropicaux (en n'étant pas spécifiques) remettent en question les idées reçues sur la mycohétérotrophie des plantes. Nous avons confirmé que (7) la mycohétérotrophie dérive d'un régime nutritionnel intermédiaire (mixotrophie) mis en place dans des lignées chlorophylliennes. Dans un dernier volet de la thèse, nous avons posé la question du déterminisme phylogénétique des associations orchidées-champignons. En analysant la force du signal dans les phylogénies des deux partenaires, nous avons vérifié que (8) les associations mycorhiziennes sont peu conservées à l'échelle supra-générique dans la phylogénie des orchidées, et qu'elles (9) peuvent être maintenues à une échelle plus récente (cas de certains clades d'angraecoïdes). Ces résultats soulignent l'empreinte relative des processus écologiques et évolutifs sur les patrons d'associations actuels, et remettent en question l'idée qu'un processus de coévolution pourrait guider le système. / Plants generally do not exploit soil nutrients themselves, but they depend upon mycorrhizal symbioses with root-associating fungi. This is the case for the current 25,000 orchid species that depend on the development of a mycorrhizal association to germinate and establish. They produce minute seeds lacking nutritional ressources required to germinate, so that they depend on the presence of suitable fungal partners to obtain carbon (heterotrophy) until the development of leaves (autotrophy). Mycorrhizal fungi remain present in the roots of adult plants where they contribute to the plant nutrition, which makes the molecular identification of fungal partners easier. Given the fact that most studies have been conducted in temperate regions, we have studied the diversity of mycorrhizal fungi in tropical orchids of La Réunion. We have found that (i) tropical orchids have the same partners as temperate and mediterranean orchids (Sebacinales, Ceratobasidiaceae, and above all Tulasnellaceae), and that these fungi are widespread in biomes and host plants. We have also showed for the first time that (ii) epiphytic orchids-that have hardly been studied-have partners that differ from terrestrial orchids' in tropical plant communities. Moreover, by developing an interaction network approach (78 species of La Réunion), we have found that (iii) most tropical species are generalists and that (iv) the mycorrhizal network shows the same properties as the mutualistic interaction networks' (nestedness and interaction asymmetry), whereas the mutualistic nature of the orchid symbiosis is still a current issue. In the second part of our thesis, we have studied the fungal partners of achlorophyllous (i.e. mycoheterotrophic) tropical orchids. We have found that (v) tropical species often associate with saprophytic fungi that provide carbon extracted from decaying wood or leaves in tropical soils, and that (vi) tropical models, because of their lack of specificity, challenge the rule drawn from temperate models. We have also confirmed in tropical models that (vii) mycoheterotrophy evolved from mixotrophic ancestors (i.e. intermediate nutritional mode). In the last part of our thesis, we have dealt with the influence of orchid and fungal phylogenies in explaining the structure of the observed networks. By measuring the phylogenetic signals in both orchid and fungal phylogenies, we have checked that (viii) mycorrhizal interactions are not explained by the phylogenetic placements of either orchid genera or fungal taxa. However, we have noticed that (ix) a phylogenetic signal can occur in recent clades of orchid species (but not in fungal species). These results provide insights in the relative imprint of ecological and evolutionary processes on the current patterns of fungus-orchid associations, and challenge the idea that the coevolutionary process could drive the system.

L'espèce cultivée Vanilla planifolia G. Jackson est un exemple typique de plante cultivée à reproduction végétative introduite depuis son aire d'origine (l'Amérique) vers de nouvelles régions où ses pollinisateurs naturels sont absents. Dans ces conditions, comment peuvent être expliquées les variations phénotypiques observées parmi les cultivars de Vanilla dans les zones d'introduction telles que l'île de La Réunion (Océan Indien) ? Elles peuvent être le résultat de différents évènements d'introduction, de mutations somatiques, de la reproduction sexuée (à travers la pollinisation manuelle), de la polyploïdie ou de phénomènes épigénétiques.<br />Les marqueurs AFLP ont été utilisés pour élucider les schémas d'introduction de V. planifolia et ils montrent que la plupart des accessions cultivées de nos jours dans les îles de l'Océan Indien dérivent d'un seul génotype introduit. A l'exception d'un phénotype particulier, ‘Aiguille' découvert à La Réunion et issu de reproduction sexuée, les accessions cultivées présentent de très faibles niveaux de diversité génétique et ont évolué grâce à l'accumulation de mutations ponctuelles à travers la multiplication végétative. Un schéma de diversification similaire a été révélé pour V. tahitensis J.W. Moore, espèce cultivée en Polynésie dérivant vraisemblablement de V. planifolia. L'analyse comparative des niveaux de diversité chez des espèces spontanées américaines génétiquement proches a révélé des niveaux faible pour V. bahiana Hoehne et élevé pour V. pompona Schiede, corrélés avec l'étendue de leur aire naturelle de dispersion et a confirmé l'existence d'un régime mixte de reproduction chez ses espèces (sexuée et végétative). Ces résultats sont confirmés par les marqueurs microsatellites développés chez V. planifolia. Les marqueurs transférables et polymorphes aux espèces sauvages américaines, africaines et asiatiques ont révélé une différenciation robuste des espèces, ainsi qu'une forte dichotomie du genre entre Ancien Monde et Nouveau Monde. Ces microsatellites seront très utiles pour les études de diversité, d'hybridation et de phylogéographie dans le genre Vanilla.<br />La cytométrie en flux, la microdensitométrie, les comptages chromosomiques et les longueurs de stomates ont montré que la polyploïdisation a joué un rôle important dans la diversification de V. planifolia à la Réunion. Trois niveaux de ploïdie (2x, 3x, 4x) ont été révélés permettant d'expliquer les particularités des phénotypes réunionnais ‘Stérile' auto-triploïde et ‘Grosse Vanille' auto-tétraploïde. V. pompona possède les caractéristiques d'un ancien tétraploïde ayant évolué soit par fusions de chromosomes soit par contraction génomique. La forte variation de la quantité d'ADN nucléaire et la fréquence élevée de l'aneuploïdie chez toutes les espèces de Vanilla étudiées, montrent de toute évidence que la polyploïdisation est un phénomène majeur et récurrent dans l'évolution du genre.<br />Il existe de la méthylation dans le génome de V. planifolia mais aucun polymorphisme de méthylation n'a permis d'expliquer les particularités des phénotypes ‘Variegata' et ‘Mexique'. L'origine de ces particularités doit être recherchée par ailleurs.<br />Comme beaucoup d'autres espèces tropicales introduites pour leur culture, le vanillier possède donc une base génétique très restreinte qui le rend vulnérable aux maladies. Chez une plante d'importance économique comme le vanillier, l'accroissement de la variabilité génétique et l'apport de nouvelles potentialités agronomiques et organoleptiques sont donc des enjeux majeurs pour la recherche. Le vanillier est d'autre part un modèle de choix pour étudier les conséquences de la domestication (à travers la reproduction végétative) mais également pour élucider l'histoire évolutive de la plus grande famille de plantes : les orchidées.

Na natureza, as orquídeas são totalmente dependentes de fungos micorrízicos para germinar. Estes fungos podem penetrar nas células das raízes e formar pélotons, os quais, quando digeridos pela planta, providenciam açúcares simples para o embrião. Durante a fase aclorofilada de desenvolvimento da plântula, orquídeas são obrigatoriamente dependentes dos fungos; algumas continuam assim por toda vida enquanto outras se tornam facultativamente responsivas à colonização. O objetivo deste trabalho foi identificar quantos clados de fungos podem estabelecer associação micorrízica com Coppensia doniana (sin. Oncidium donianum), uma orquídea amplamente distribuída nos arredores de Campos do Jordão e, demonstrar como as características morfológicas dos isolados, quando analisadas com ferramentas de estatística multivariada, podem ser úteis para a taxonomia destes fungos. Dez plantas foram amostradas em um sítio com vegetação típica de campos de altitude, junto ao Parque Estadual de Campos do Jordão. Fungos foram isolados pela transferência asséptica de cortes de raízes contendo pélotons para meios de cultura BDA modificados. Três clados de fungos foram formados, tanto analisando as características qualitativas das culturas quanto as quantitativas. Os clados foram identificados como dois morfotipos do gênero Ceratorhiza (fase anamórfica de Ceratobasidium) e uma Rhizoctonia-uninucleada. O sequenciamento da região ITS produziu resultados idênticos a estes, mostrando os mesmos três clados. Todas as sequências tiveram alta correlação com sequências de Ceratobasidium depositadas no Genbank, o que sugere uma alta afinidade de Coppensia doniana com este gênero. Também ficou demonstrado que os dados morfológicos, quando associados à estatística multivariada são uma ferramenta útil na taxonomia polifásica de Rhizoctonia spp. As sequências dos isolados de Coppensia doniana também foram comparadas com as de isolados de outras orquídeas, dentro da subtribo Oncidiinae, incluindo: Ionopsis utricularioides e Psygmorchis pussila, coletadas na região do Valle del Cauca Colômbia e isolados de 10 Ionopsis utricularioides, Oncidium altissimum e Tolumnia variegata, estudados por Otero (2002, 2004, 2007), em diferentes regiões de Porto Rico, Costa Rica, Cuba e Panamá. Esta última análise veio a comprovar a preferência de orquídeas da subtribo Oncidiinae por fungos do gênero Ceratobasidium, apesar de que os clados obtidos no Brasil e na Colômbia foram distantes filogeneticamente dos clados previamente estudados na América Central. Representantes dos três clados obtidos de C. doniana em Campos do Jordão foram também testados quanto à capacidade de induzir germinação em suas sementes. Todos isolados testados tiveram sucesso na germinação das sementes, levando as plântulas a estádios avançados de desenvolvimento após 30 dias, o que indica um alto potencial para utilização biotecnológica destes isolados para a germinação das sementes destas orquídeas, tanto para a floricultura comercial quanto para programas de reintrodução de espécies de orquídeas ameaçadas de extinção. / In nature, orchids are fully dependent on mycorrhizal fungi for germination. These fungi can penetrate root cells and form pelotons, whose digestion provides simple sugars for the embryo. During the achlorophyllous seedling stage, orchids are obligatory dependent on the fungi, and some species remain so through life, while others become facultatively responsive to fungal infection. The aim of this study was to identify how many fungal clades can establish mycorrhizal associations with Coppensia doniana, a widespread orchid from Campos do JordãoBrazil, and to demonstrate how their morphological features, analyzed with multivariate statistics, can be useful for classification. Ten plants were sampled in an Araucaria forest near Campos do Jordão. Fungi were isolated by transferring surface disinfected root segments containing pelotons to PDA culture medium. Three main fungal clades were formed by qualitative and quantitative morphological data. They were identified as two morphotypes of Ceratorhiza (anamorphic stage of Ceratobasidium) and one uninucleated Rhizoctonia. The ITS sequencing corroborates this identification, since the same three clades were found. All sequences were highly correlated to Ceratobasidium ITS data deposited at the Genebank, suggesting a high affinity between this species of Oncidiinae and Ceratobasidium. It also could be shown that morphological data associated with multivariate statistics can be a useful tool in fungal multi-level taxonomy. C. doniana sequences were also compared to sequences obtained from isolates of other orchids, belonging to the sub-tribe Oncidiinae, including: Ionopsis utricuarioides and Psygmorchis pussila, collected in Valle del Cauca Colombia and isolated from I. utricularioides, Oncidium altissimum and Tolumnia variegata, studied by Otero (2002, 2004, 2007) in different regions of Puerto Rico, Costa Rica and other Caribbean islands. This last analysis confirmed the preference of this Oncidiinae sub-tribe for Ceratobasidium, although isolates obtained in Brazil or Colombia belong to different clades from those previously studied in Puerto Rico, Costa Rica, Panama and Cuba. 12 Fungi representing the three clades obtained from C. doniana in Campos do Jordão were also tested for their ability to induce germination of C. doniana seeds, with a positive response for all of them, being able to bring the seedlings to advanced development stages in 30 days. These results suggest a high biotechnological potential of these isolates, to be used in orchid symbiotic germination for commercial flower production or for the reintroduction of endangered Brazilian orchid species.

L'objectif de ce travail est de ntica (évolution et schémas de biodiversité) à travers une étude pluridisciplinaire du genre Baptistonia axée sur trois grands volets : taxinomique, phylogénétique, écologique. Les résultats les plus significatifs du premier concernent (a) de nouveaux transferts et synonymies qui ont abouti à retenir 23 espèces ; (b) la proposition d'outils morphométriques pour séparer des espèces ambiguës ; (c) la description morphologique et iconographique de chaque espèce ; et (d) l'organisation du genre en six sections. L'étude phylogénétique, basée sur la morphologie, les séquences moléculaires de plusieurs régions de plastides, des marqueurs ISSR, la composition des huiles florales, a permis (a) de confirmer la monophylie du genre ; (b) de confirmer que cet ensemble est bien distinct des genres voisins du clade Gomesa ; (c) de proposer un cladogramme des espèces ; et (d) de formuler des hypothèses d'évolution en cohérence avec la théorie des refuges. L'étude de la biologie de la conservation a permis de préciser : (a) l'extension géographique et le profil climatologique de la Mata Atlântica ; (b) quelques facteurs biologiques et écologiques des Baptistonia ; (c) la distribution géographique de chaque espèce ; (d) les schémas de biodiversité du genre, avec une première ébauche de régions prioritaires pour la préservation des habitats. contribuer à l'étude de la Mata Atlâ

<p>Small populations are facing a particular risk of extinction due to a lack of appropriate genetic diversity and associated negative effects, factors dealt with in the discipline of conservation genetics. Many orchid species exhibit characteristics that make them a perfect study object in the scope of conservation genetics. The aim with this thesis was to investigate genetic structure at different levels in two orchid species <i>Gymnadenia conopsea</i>, geographically widespread, although diminishing and <i>G. odoratissima</i> with a long history of being rare. Microsatellite markers, developed in and used in studies of <i>G. conopsea</i> were also used in the study of <i>G. odoratissima</i>.</p><p>Populations of <i>G. conopsea</i> expressed high levels of genetic variation and a certain amount of gene flow, although investigated mating pattern in a small population indicated non-random mating among individuals, with the majority of pollen exchange between near neighbours, and noticeable levels of geitonogamous pollinations. Further a pronounced year to year variation in flowering frequency among individuals was found. </p><p>It was also discovered that flowering time variants (early and late) within the species <i>G. conopsea</i> were highly differentiated and seem to have had a more ancient historical separation than the separation between the two different species, <i>G. conopsea</i> and <i>G. odoratissima. </i></p><p>Levels of genetic variation in the rare congener, <i>G. odoratissima</i> differed between island and mainland populations where the more numerous island populations expressed larger levels of genetic variation and were less differentiated compared to the few remaining and genetically depauperated mainland populations.</p><p>Uppsala University Library, Box 510, 75120, Uppsala, Sweden </p>

Small populations are facing a particular risk of extinction due to a lack of appropriate genetic diversity and associated negative effects, factors dealt with in the discipline of conservation genetics. Many orchid species exhibit characteristics that make them a perfect study object in the scope of conservation genetics. The aim with this thesis was to investigate genetic structure at different levels in two orchid species Gymnadenia conopsea, geographically widespread, although diminishing and G. odoratissima with a long history of being rare. Microsatellite markers, developed in and used in studies of G. conopsea were also used in the study of G. odoratissima. Populations of G. conopsea expressed high levels of genetic variation and a certain amount of gene flow, although investigated mating pattern in a small population indicated non-random mating among individuals, with the majority of pollen exchange between near neighbours, and noticeable levels of geitonogamous pollinations. Further a pronounced year to year variation in flowering frequency among individuals was found. It was also discovered that flowering time variants (early and late) within the species G. conopsea were highly differentiated and seem to have had a more ancient historical separation than the separation between the two different species, G. conopsea and G. odoratissima. Levels of genetic variation in the rare congener, G. odoratissima differed between island and mainland populations where the more numerous island populations expressed larger levels of genetic variation and were less differentiated compared to the few remaining and genetically depauperated mainland populations. Uppsala University Library, Box 510, 75120, Uppsala, Sweden

The survey presented in this thesis focused on germination of six orchid species in the Protected landscape area White Carpathians; specifically Platanthera bifolia, Neottia ovata, Anacamptis pyramidalis, Gymnadenia conopsea subsp. conopsea, Traunsteinera globosa, Orchis militaris on restored medows of various age. As the control, two National Protected Areas (Zahrady pod Hájem and Čertoryje) were used. The initial stage of germination was detected on both restored and control meadows. The advanced stage of germination (protocorm) was recorded in three species (GC, NO, PB) on restored meadows, and in all species on kontrol meadows. The other aim of the thesis was to determine via molecular methods, which species of mycorrhizal fungi are associated with the model orchid species.

Cattleya é um gênero Neotropical com 114 espécies, sendo mais da metade destas exclusivas do Brasil. Embora as espécies de Cattleya sejam de grande importância horticultural, o número de trabalhos relativos à polinização, sistema reprodutivo e comportamento dos polinizadores é bastante reduzido. No presente trabalho foram analisadas onze populações para quatro espécies, das quais três são ameaçadas (de acordo com os critérios da IUCN) e nativas de Cattleya do Rio Grande do Sul, Brasil. Apresentamse resultados de caracterização morfológica, fenologia floral, sistema reprodutivo, remoção e deposição de polinários, sucesso na formação de frutos e interações com os polinizadores para C. coccinea, C. intermedia, C. tigrina e C. purpurata. Foi documentada pela primeira vez a polinização de C. intermedia, C. purpurata e C. tigrina por quatro espécies de abelhas dos gêneros Xylocopa, Bombus e Epicharis. A visitação exclusiva por beija-flores foi corroborada para C. coccinea. De um modo geral, as espécies mostraram-se autocompatíveis, mas polinizadores dependentes. Verificou-se nas quatro espécies ausência de néctar e um sistema de polinização baseado no mecanismo por engodo. Encontrou-se que em todas as espécies estudadas a taxa de visitas é baixa e a frutificação em condições naturais é infrequente. Verificou-se nas quatro espécies um maior sucesso na formação de frutos através de polinização cruzada. / Cattleya Lindl. is a Neotropical genus that comprises 114 species with more than a half restricted to Brazil. In spite of the horticultural importance of the Cattleya species their pollination, reproductive system, and behaviour of its pollinators is poorly known. In this work were analized eleven populations of four species, of which three are endangered (according to the IUCN criteria) native species of Cattleya from Rio Grande do Sul, Brazil. Here are shown data and results of morphological caracterization, floral phenology, reproductive system, pollinary removal and deposition, fruit set success, and interactions with the pollinator for C. coccinea, C. intermedia, C. tigrina and C. purpurata. It was documented for first time the pollination of C. intermedia, C. purpurata and C. tigrina by four bee species from the genus Xylocopa, Bombus and Epicharis. The exclusive visitation from the hummingbird was confirmed for C. coccinea. All studied species are selfcompatible, but pollinator dependent. There were also verified a lack of reward, and a pollination system based on deceit for the four species. The findings show that in all the studied species the visitation ratio is low, and the natural fruiting has a low frequency. All studies species showed higher fruit production after cross-pollination.

Abstract A population growth rate is the sum of all individuals’ reproduction and survival, which in turn depend on many external and internal factors, e.g. weather and individual reproductive history. In plants, for example, previous reproduction can deplete an individual’s resources, resulting in trade-offs between demographic functions. To understand these demographic processes, it is necessary to follow populations for many years. Such long-term studies are especially crucial for endangered species, as they can reveal the causes of population declines and provide information that is directly applicable for the management. In my thesis, I applied this approach to the study of rare orchids. Specifically, I analyzed long-term orchid monitoring data from two countries, Finland and Estonia, to assess the external and internal factors that affect the performance of these long-lived plants, which reproduce both sexually (via seeds) and vegetatively (via new ramets). My research reveals that plant performance depends on both the demographic history and the environment of a plant. For example, although Finnish and Estonian populations of the lady’s slipper orchid, Cypripedium calceolus, differed in direction and statistical significance of their responses to environmental factors, the two most-influential weather variables in both cases were spring snow depth and the temperature of the previous summer. However, the influence of weather on both flowering and vegetative growth was dwarfed by the effect of plants’ own demographic histories: there was a trade-off between current and future reproduction which created asynchronous two-year cycles in reproduction and growth. Furthermore, in all three studied orchid species — the lady’s slipper orchid (C. calceolus), the fairy’s slipper orchid (Calypso bulbosa), and the dark-red helleborine (Epipactis atrorubens) — the probability of dormancy (a state in which the plant spends a year or more underground) and the demographic costs this state incurred with respect to size or future reproduction depended on a plant’s size and whether it flowered prior to dormancy. In other words, dormancy had both absolute and relative costs in large, but not in small, individuals. Finally, I show here that environmental alteration via selective tree removal can be used as a management method to increase orchid reproduction via both seeds and ramets. / Tiivistelmä Populaation kasvunopeus riippuu siitä, kuinka monta yksilöä populaatioon syntyy ja kuinka monta yksilöä kuolee. Yksilöiden lisääntyvyyteen ja elossa säilyvyyteen puolestaan vaikuttavat monet ulkoiset ja sisäiset tekijät, kuten sää ja yksilön oma lisääntymishistoria. Kasvilla on rajallinen määrä resursseja, joten sen pitää tehdä kompromisseja eri elintoimintojen, esimerkiksi kasvun ja lisääntymisen, välillä. Klonaaliset kasvit voivat myös lisääntyä usealla tavalla: joko suvullisesti siemenistä tai kasvullisesti tuottamalla uusia versoja. Demografisten prosessien tutkimisessa pitkäaikaiset seuranta-aineistot ovat välttämättömiä. Pitkäaikaisseurannat voivat myös paljastaa uhanalaisen lajin populaation taantumisen syyt ja näistä seurannoista saatua tietoa voidaan soveltaa harvinaisten lajien, esimerkiksi kämmeköiden, suojelutoimien suunnittelussa. Tässä väitöskirjassa analysoin aineistoa kämmeköiden pitkäaikaisseurannoista Suomesta ja Virosta. Tavoitteenani oli arvioida ulkoisten ja sisäisten tekijöiden merkitystä pitkäikäisten kasvien menestykselle. Tulokset osoittavat, että kasvin menestys riippuu sekä yksilön omasta demografisesta historiasta että sen ympäristöstä. Eri säätekijöiden vaikutus tikankontin (Cypripedium calceolus) kasvuun ja kukkimiseen vaihteli Suomen ja Viron välillä, mutta lumen syvyys ja edellisen kasvukauden lämpötila nousivat merkittävimmiksi tekijöiksi molemmissa maissa. Tikankontin kasvu ja kukinta riippuivat kuitenkin säätä enemmän kasvin omasta demografisesta historiasta. Runsas lisääntyminen edeltävällä kasvukaudella vähensi lisääntymistä tulevalla kasvukaudella, mikä johti kaksivuotiseen jaksottaisuuteen tikankontin lisääntymisessä ja kasvussa. Tutkiessani dormanssia (lepotila, jossa kasvi ei tuota maanpäällistä versoa) kolmella kämmekkälajilla, tikankontilla, neidonkengällä (Calypso bulbosa) ja tummaneidonvaipalla (Epipactis atrorubens), havaitsin lisäksi, että todennäköisyys siirtyä dormanssiin riippui kasvin koosta. Myöskin tämän lepotilan aiheuttamat kustannukset olivat riippuvaisia kasvin aikaisemmasta tilasta. Isoilla kasveilla dormanssilla oli sekä suoria kustannuksia että kustannuksia suhteessa versomiseen. Pienillä kasveilla näitä kustannuksia ei ollut. Osoitan väitöskirjassani myös, että maltillisella puunpoistolla voidaan lisätä tikankonttipopulaatioiden siementuottoa ja versotiheyttä.

Cattleya é um gênero Neotropical com 114 espécies, sendo mais da metade destas exclusivas do Brasil. Embora as espécies de Cattleya sejam de grande importância horticultural, o número de trabalhos relativos à polinização, sistema reprodutivo e comportamento dos polinizadores é bastante reduzido. No presente trabalho foram analisadas onze populações para quatro espécies, das quais três são ameaçadas (de acordo com os critérios da IUCN) e nativas de Cattleya do Rio Grande do Sul, Brasil. Apresentamse resultados de caracterização morfológica, fenologia floral, sistema reprodutivo, remoção e deposição de polinários, sucesso na formação de frutos e interações com os polinizadores para C. coccinea, C. intermedia, C. tigrina e C. purpurata. Foi documentada pela primeira vez a polinização de C. intermedia, C. purpurata e C. tigrina por quatro espécies de abelhas dos gêneros Xylocopa, Bombus e Epicharis. A visitação exclusiva por beija-flores foi corroborada para C. coccinea. De um modo geral, as espécies mostraram-se autocompatíveis, mas polinizadores dependentes. Verificou-se nas quatro espécies ausência de néctar e um sistema de polinização baseado no mecanismo por engodo. Encontrou-se que em todas as espécies estudadas a taxa de visitas é baixa e a frutificação em condições naturais é infrequente. Verificou-se nas quatro espécies um maior sucesso na formação de frutos através de polinização cruzada. / Cattleya Lindl. is a Neotropical genus that comprises 114 species with more than a half restricted to Brazil. In spite of the horticultural importance of the Cattleya species their pollination, reproductive system, and behaviour of its pollinators is poorly known. In this work were analized eleven populations of four species, of which three are endangered (according to the IUCN criteria) native species of Cattleya from Rio Grande do Sul, Brazil. Here are shown data and results of morphological caracterization, floral phenology, reproductive system, pollinary removal and deposition, fruit set success, and interactions with the pollinator for C. coccinea, C. intermedia, C. tigrina and C. purpurata. It was documented for first time the pollination of C. intermedia, C. purpurata and C. tigrina by four bee species from the genus Xylocopa, Bombus and Epicharis. The exclusive visitation from the hummingbird was confirmed for C. coccinea. All studied species are selfcompatible, but pollinator dependent. There were also verified a lack of reward, and a pollination system based on deceit for the four species. The findings show that in all the studied species the visitation ratio is low, and the natural fruiting has a low frequency. All studies species showed higher fruit production after cross-pollination.