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Flores de antese noturna e seus polinizadores em área de caatinga: redes e sistemas mistos de polinizaçãoQUEIROZ, Joel Araújo 21 February 2014 (has links)
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Previous issue date: 2014-02-21 / CNPQ / As espécies de plantas com flores de antese noturna e seus polinizadores,
principalmente, morcegos e mariposas Sphingidae (mariposas de aparelho bucal longo e
de hábito predominantemente noturno) foram estudadas no presente trabalho através de
abordagens de teoria de redes complexas e de biologia floral (para três espécies de
plantas: Encholirium spectabile (Bromeliaceae); e duas espécies de Ipomoea
(Convolvulaceae). Entre janeiro/2011 e dezembro/2012 foram realizadas expedições
mensais a um remanescente de Caatinga hiperxerófila situada no Nordeste do Brasil,
para coleta de esfingofauna (com auxílio de armadilha luminosa) e de morcegos (com
redes de neblina). A carga polínica presente no corpo desses polinizadores foi coletada e
os tipos polínicos identificados e quantificados, sendo tais dados usados para construir
matrizes qualitativas (presença/ausência) e quantitativas (frequência de individuos com
pólen de determinada espécie de planta) para análise interanual de modularidade e
robustez da rede de interações. Para as espécies E. spectabile, Ipomoea marcellia e I.
aff. marcellia foram coletados dados de morfometria floral (comprimento e largura de
corola), antese (início, término e duração total), atributos de néctar (volume,
concentração, mg de açúcares, padrão de produção e efeito de remoção) e frequência de
visitantes florais diurnos e noturnos. Para as espécies de Ipomoea a eficiência de
morcegos e beija-flores foi estimada através de experimentos de exposição seletiva de
flores. A rede de interações entre plantas e polinizadores noturnos foi formada por 24
espécies de plantas, 4 morcegos e 15 esfingídeos, sendo registradas 766 conexões totais.
A rede apresentou estrutura modular de 0.36, sendo observados três módulos distintos:
dois exclusivos de esfingídeos e um misto (morcegos + esfingídeos). No entanto, foi
observada intensa frequência de conexões inter-módulos o que pode indicar uma
fronteira não tão bem delimitada da guilda de plantas quiropterófilas. A rede apresentou
robustez à extinção de espécies variável entre os dois anos de coleta, o que pode ser o
resultado do menor tamanho (Rede2011: 42 espécies; Rede2012: 29 espécies) e menor
quantidade de conexões (Rede2011: 573; Rede2012: 193) resgistrados no ano mais seco.
As espécies E. spectabile, I. marcellia e I. aff. marcellia, de modo geral, apresentaram
atributos de morfometria floral mais relacionados à quiropterofilia (polinização por
morcegos). No entanto, a morfologia floral e períodos de antese e de disponibilidade de
néctar prolongados para além da noite, possibilitaram a beija-flores acessarem néctar e
transferirem, com certo grau de sucesso, pólen para o estigma, garantindo um serviço de
polinização complementar. Esse sistema de polinização, denominado polinização mista,
parece ser uma estratégia recorrente para algumas espécies de Caatinga primariamente
relacionadas à polinização por morcegos, podendo garantir maior sucesso reprodutivo
para tais plantas. / Plant species with nocturnal flowers and their pollinators, especially bats and hawmoths
were studied in this work through complex networks theory approaches and floral
biology (for three species of plants: Encholirium spectabile (Bromeliaceae), and two
Ipomoea taxa (Convolvulaceae). Between January/2011 and December/2012 were
carried out monthly mailings to a remnant of Caatinga hyperxerophilic located in
northeastern Brazil, to moth collect (with aid of light trap) and bats (with mist nets). the
pollen load present in the body of these pollinators were collected, identified, and
quantified pollen types, and such data used to construct qualitative (presence / absence)
and quantitative matrices (frequency of individuals with pollen) to analysis of
modularity and robustness of network. To E. spectabile, Ipomoea marcellia and I. aff.
marcellia were collected floral morphometry (length and width corolla), anthesis (start,
end and total duration), nectar attributes (volume, concentration, sugars, pattern of
production and removal effect) and frequency flower visitors day and night. To
Ipomoea, bats and hummingbirds efficiency was estimated by experiments of selective
exposure flowers. The mutualistc network plants and pollinators was formed by 24 plant
species, 15 hawkmoths and 4 bats. It was recorded 766 connections. That network
presented modular structure, 0.36, with three distinct modules: two exclusive
hawkmoths and a mixed hawkmoths and bats). However, there was intense frequency of
inter-module connections, which may indicate a boundary not as well defined Guild
chiropterophilous plants. The network showed variable robustness between years (2011:
Rplant = 0.96; Ranimal = 0.92; 2012: Rplant = 0:33; Ranimal = 0:33), which may be
the result of the smaller size (2011: 42 species; 2012: 29 species) and fewer
connections. E. spectabile, I. marcellia and I. aff. marcellia showed more attributes
related to chiropterophily (pollinated by bats). However, the floral morphology and
anthesis periods and prolonged nectar availability in addition to the night, made it
possible to access hummingbirds nectar and transfer, with some degree of success,
pollen to the stigma, ensuring a supplementary pollination service. This pollination
system called mixed pollination, seems to be a recurring strategy for some species of
Caatinga primarily related to pollination by bats and can ensure greater reproductive
success for such plants.
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Délimitation taxonomique et étude de la biologie de la reproduction du genre africain Cyrtorchis Schltr. (Orchidaceae)Azandi Ngnintedem, Laura 27 May 2021 (has links) (PDF)
Le genre Cyrtorchis, groupait 18 espèces d’orchidées angraecoïdes endémiques d'Afrique tropicale, était connu pour ses grandes fleurs blanches, odorantes à long éperon bien adaptées pour des études sur la biologie de la reproduction. Il était également connu pour ses problèmes de délimitation taxonomique qui peuvent s’avérer préjudiciables pour la conservation des espèces.La présente thèse de doctorat ambitionne de résoudre les problèmes de délimitation au sein du genre au niveau inter et intraspécifique en utilisant une approche de taxonomie intégrative et de documenter sa biologie de la reproduction.Une inspection visuelle de 1752 spécimens, les analyses morphométriques et phylogénétiques ont été utilisées pour clarifier la taxonomie au sein du genre. L’inspection visuelle a permis de délimiter 27 morphogroupes à priori, desquels un échantillonnage de 171 spécimens représentant 20 morphogroupes a été utilisé pour les analyses morphométriques. Pour les reconstructions phylogénétiques, 69 spécimens représentant 21 des 27 morphogroupes ont été séquencés à partir de six marqueurs moléculaires. La caractérisation des patrons de floraison et l’observation et des pollinisateurs ont été réalisées au Cameroun grâce à un suivi phénologique en ombrière sur trois ans de 494 spécimens vivants représentant 15 taxons, et un suivi de la pollinisation naturelle in situ de deux de ces taxons. L’évaluation des facteurs affectant la production des fruits et des graines viables a été réalisée chez deux espèces du genre à travers 448 tests de pollinisation manuelle pour lesquels l’effet du système de pollinisation et de la limitation des ressources ont été examinés.Les approches morphologiques permettent de distinguer deux groupes correspondant aux deux sections préalablement identifiées pour le genre Cyrtorchis. Les analyses moléculaires quant à elles ne soutiennent que la monophylie d’une des deux sections, Cyrtorchis sect. Cyrtorchis. Huit taxons morphologiquement définis dans le genre incluant trois nouvelles espèces sont également bien supportés par les analyses morphométriques et phylogénétiques. Le point d’insertion des stipites au tier supérieur du viscidium semble être l’un des principaux caractères reproducteurs soutenant la monophylie du genre alors que d’autres traits (tels que la structure du viscidium, la forme des stipites et des lobes latéraux du rostelle) se révèlent être d’importants critères permettant d’inférer des relations phylogénétiques au sein du genre. Au final, cette analyse met en évidence 27 taxons au sein du genre(incluant six nouveaux taxons à décrire), dont 12 taxons, confirmé par les approches morphométriques et/ou phylogénétiques. La phénologie de la floraison des espèces en ombrière montre un pic de floraisons à la grande saison de pluie (entre août et octobre). Un décalage de la floraison est observé chez certains taxons distribués en sympatrie et un asynchronisme de la floraison entre population de la même espèce. La pollinisation naturelle est un évènement rare et difficile à observer chez les deux espèces étudiées (C. letouzeyi et C. okuensis). En effet, le taux de pollinisation/fructification est globalement faible (39 % de fleurs avec les pollinies emportées et 16 % de fruits produits chez C. okuensis ;31-15 % de fleurs avec les pollinies emportées et 7-4 % de fruits produits chez C. letouzeyi), et ce, à cause du nombre réduit des visites des pollinisateurs. Par ailleurs, les pollinisateurs des deux espèces ont été identifiés et la pollinisation par les sphinx est confirmée dans le genre. Les tests de pollinisation manuelles ont révélé que la pollinisation croisée semble être le système de pollinisation le plus efficace pour la production de fruits et de graines viables. Cependant, davantage d’espèces devront être testées pour confirmer ce patron. Les approches multidisciplinaires développées dans ce travail sont des bases solides pour la définition et la mise en œuvre de stratégies efficaces de conservation pour les espèces d’orchidées menacées. Afin de produire une révision taxonomique complète du genre, une phylogénie complète incluant les cinq taxons restants et ceux encore non résolus est nécessaire. Les nouveaux taxons identifiés devraient être décrits et les statuts de conservation évalués pour l’ensemble des espèces reconnues dans le genre. / The genus Cyrtorchis, grouped of 18 angraecoid orchids species endemic to tropical Africa, and was known for its large, white, fragrant flowers with a long spur well suited for studies on reproductive biology. It was also known for its taxonomic delimitation problems, which can be detrimental to the conservation of the species.This PhD thesis aims to address the delimitation problems within the genus at the inter- and intraspecific level using an integrative taxonomic approach and to investigate its reproductive biology.Visual inspection of 1752 specimens, morphometric and phylogenetic analyses was used to clarify the taxonomy within the genus. Visual inspection delineated 27 a priori morphogroups, from which a sample of 171 specimens representing 20 morphogroups was used for morphometric analyses. For phylogenetic reconstructions, 69 specimens representing 21 of the 27 morphogroups were sequenced with six molecular markers. The characterization of flowering patterns and the observation of pollinators were carried out respectively through a three-year shadehouse phenological survey of 494 living specimens representing 15 taxa and a survey of the natural in situ pollination of two taxa in Cameroon. The assessment of factors affecting fruit and viable seed production was carried out in two species of the genus through 448 hand pollination tests for which the effect of pollination system and resource limitation were examined.Morphological approaches allow to distinguish two groups corresponding to the two sections previously identified for the genus Cyrtorchis. Molecular analyses support only the monophyly of on of the sections, Cyrtorchis sect. Cyrtorchis. Eight morphologically defined taxa including three new species are also well supported by morphometric and phylogenetic analyses. The insertion point of the stipites at the rear third of the length of the viscidium appears to be one of the main reproductive characters supporting the monophyly of the genus while other traits (such as the viscidium structure, the shape of the stipites and the lateral lobes of the rostellum) are found to be important criteria for inferring phylogenetic relationships within the genus. Finally this analysis highlights 27 taxa within the genus (including six new taxa to be described), of which 12 taxa, confirmed by morphometric and/or phylogenetic approaches. Flowering of most species at the shadehouse is peaking during the main rainy season (between August and October). However, some sympatric species present non-overlapping flowering periods and an asynchronism of flowering between populations of the same species. Natural pollination is a rare event and difficult to observe in the two studied species. Indeed, the overall pollination/fruiting rate is low (39% of flowers with pollinia removed and 16% of fruits produced in C. okuensis; 31-15% of flowers with pollinia removed and 7-4% of fruits produced in C. letouzeyi) because of the reduced number of pollinators visits. Additionally, both species were found to be pollinated by hawkmoths. Manual pollination tests revealed that cross-pollination appears to be the most efficient pollination system to produce fruits and viable seeds. However, more species will need to be tested to confirm this pattern.The multidisciplinary approaches developed in this work provide a solid basis to define and implement effective conservation strategies for threatened orchid species. To produce a complete taxonomic revision of the genus, a completed phylogeny including the five remaining and the yet unresolved taxa is required. The newly identified taxa should be described and the conservation status assessed for all species recognised in the genus. / Option Biologie des organismes du Doctorat en Sciences / info:eu-repo/semantics/nonPublished
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