Enyalius perditus e Enyalius iheirngii são duas espécies de lagartos semi- arborícolas pertencentes à nova família Leiosauridae. Apresentam hábitos diurnos, são forrageadores ativos, e estão distribuídos ao longo da Mata Atlântica. E. perditus ocorre na porção sudeste enquanto E. iheringii nas porções sudeste e sul com registros de co-ocorrência em áreas do Estado de São Paulo. Apesar de sua ampla distribuição pouco se conhece sobre a ecologia e menos ainda sobre a biologia reprodutiva do gênero Enyalius. Além disto, informações sobre o comportamento reprodutivo de corte, época de cópula, desova e nascimento dos filhotes são praticamente inexistentes. Para tanto, este estudo investigou a estratégia reprodutiva de ambas as espécies através da dissecção de animais provenientes de coleções científicas, de cativeiro e de coletas em campo. Machos e fêmeas de E.iheringii atingiram maturidade sexual em tamanhos similares. Ambas as espécies são mais abundantes durante a estação chuvosa do que na estação seca. Ciclo de fêmeas de E. iheringii são mais estendidos e há possibilidade dos machos estocarem o espermatozoides nos ductos deferentes durante todo o ano. Foram encontradas fêmeas de E. iheringii estocando espermatozoides durante a primavera no infundíbulo e no outono dentro das criptas de estocagem da junção uterino-vaginal. Nas fêmeas de E. perditus a reprodução é altamente sazonal e ocorre nos períodos mais quentes e úmidos do ano. / Enyalius perditus and Enyalius iheirngii are two semi-arboreal lizard species that belong to the new family Leiosauridae. These specimens present daytime behavior and are active forragers distributed across the Atlantic Rainforest. E. perditus are found in the Southeast and E. iheringii in the Southeast and South. They also present co- occurrence in some areas at São Paulo state. Despite their wide distribution, little is known about their ecology and even less about the reproductive biology of their genera. The information about the reproductive biology of these animals is scarce on the other hand data regarding courtship behavior, mating season, spawning and offspring birth is virtually absent. For this, this study investigated the reproductive strategy of both species through the dissection of animals from scientific collections, captivity and field collections. In E.iheringii males and females reached sexual maturity in similar sizes. Both species are more abundant during the rainy season than in the dry season. Cycle of females of E. iheringii appear more extended and there is possibility of males stocking the spermatozoa in the vas deferens throughout the year. Females of E. iheringii were found stocking sperm during the spring in the infundibulum and in the fall within the storage crypts of the uterine-vaginal junction. In E. perditus females reproduction is highly seasonal and occurs during the hottest and wettest periods of the year.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Tree cavities are an important natural resource found in many habitats, providing breeding sites and shelter for arthropods, birds and mammals. However, nest boxes have been more frequently used in Brazil as a tool aiming the conservation of endangered psittacids. In view of this fact, the general objective of the present dissertation was to verify how the use of the artificial tree cavities by vertebrates and invertebrates occurs. In this study we tested the following hypotheses: 1) due to a possible lack of natural cavities at the forest edge, there will be a greater use of the artificial cavities at the edge than inside; 2) there will be an increased use of the artificial cavities by the exotic species at the edge than inside; 3) because there are natural predators, native species should prefer little depth nests and nests with small openings; 4) due to the edge effect, there will be a decline in the availability of natural cavities of the interior in the edge direction and 5) in transects with lower availability of natural cavities, there will be a greater use of the nest boxes. To carry out this work, we selected a subtropical Atlantic forest fragment, with an area of 80 ha, located in Santa Maria, Rio Grande do Sul, Brazil. Ten transects were established (five in edge and five inside the fragment), in which 120 artificial nests were hung (60 nests on the edge and 60 inside). The nests were installed in August 2013 and monitored every six days, between September and December 2013 and between September and December 2014. In order to allow the use of the nests by various groups of animals, these nests were made with medium and large-sizes (20 x 30 cm base and 30 cm high x 45 cm), with little or great depth (opening at the top or in the middle of the nest) and small openings (5 cm diameter), medium (10 cm) and large (15 cm). Inside the fragment, there were 29 uses and in the edge 31 uses. Hymenoptera was the most frequent group, corresponding to 61.40% of the occupations (35 of the 60 occupied boxes). Araneomorphae was the second most frequent group with 13 occupied nests; nine nests were occupied by birds (generating 17 chicks, 16 of Pyrrhura frontalis and a chick of Dendrocolaptes platyrostris). Mammals were the least frequent group with only three used boxes (two nests occupied by Didelphis albiventris and one by Guerlinguetus sp.). It was also observed a greater availability of natural cavities inside (50) than at the edge (14), which was considered significant through the statistical test of Mann-Whitney, since the p value was 0.047. Generally the native species sought more cavities with small and little depth openings, while the exotic species (A. mellifera) proved generalist. It was verified, therefore, that it was more difficult for birds and mammals to accept artificial cavities in a short time while the exotic species has demonstrated a rapid acceptance of these structures. / Cavidades arbóreas constituem um importante recurso natural presente em diversos hábitats, fornecendo sítios de reprodução e abrigo para artrópodes, aves e mamíferos. Entretanto, cavidades artificiais têm sido mais frequentemente utilizadas, no Brasil, como uma ferramenta que visa a conservação de psitacídeos ameaçados de extinção. Tendo em vista este fato, a presente dissertação teve como objetivo geral verificar como ocorre a utilização de ninhos artificiais por vertebrados e invertebrados. Neste trabalho foram testadas as seguintes hipóteses: 1) devido a uma possível carência de cavidades arbóreas na borda, haverá maior utilização de ninhos artificiais na borda do que no interior; 2) haverá maior utilização de cavidades artificias por abelha-doméstica na borda do que no interior; 3) por possuírem predadores naturais, as espécies nativas devem preferir ninhos grandes e ninhos com aberturas pequenas; 4) devido ao efeito de borda, haverá uma menor disponibilidade de cavidades arbóreas no interior do que na borda e 5) nas transecções com menor disponibilidade de cavidades arbóreas, haverá maior utilização de caixas-ninho. Para a realização deste trabalho foi selecionado um fragmento de Mata Atlântica subtropical, com área de 80 ha, localizado no município de Santa Maria, Rio Grande do Sul, Brasil. Foram delimitadas 10 transecções (cinco na borda e cinco no interior do fragmento) onde foram instalados 120 ninhos artificiais (60 ninhos na borda e 60 no interior). Os ninhos foram instalados no mês de agosto de 2013 e monitorados a cada seis dias, entre setembro e dezembro de 2013 e entre setembro e dezembro de 2014. A fim de permitir a utilização dos ninhos por diversos grupos de animais, estes foram confeccionados com tamanhos médio e grande (20 cm de base x 30 de altura e 30 cm x 45 cm), com pouca ou grande profundidade (abertura no alto ou no meio do ninho) e aberturas pequenas (5 cm de diâmetro), médias (10 cm) e grandes (15 cm). No interior do fragmento, ocorreram 29 utilizações e na borda 31 utilizações. Hymenoptera foi o grupo mais frequente, correspondendo a 61,40% das ocupações (35 das 60 caixas ocupadas). Araneomorphae foi o segundo grupo mais frequente com 13 ninhos ocupados; nove ninhos foram ocupados por aves (gerando 17 filhotes, 16 de Pyrrhura frontalis e um filhote de Dendrocolaptes platyrostris). Os mamíferos foram o grupo menos frequente com apenas três caixas utilizadas (dois ninhos ocupados por Didelphis albiventris e um Guerlinguetus sp.). Foi constatada ainda uma maior disponibilidade de cavidades naturais no interior (50) do que na borda (14), o que através do teste estatístico de Mann-Whitney foi significativo (p = 0,04). De modo geral as espécies nativas procuraram mais cavidades com aberturas pequenas e pouco profundas, enquanto a espécie exótica (A. mellifera) mostrou-se generalista. Portanto a conservação de áreas florestadas é de extrema importância para manutenção de sítios reprodutivos, como as cavidades arbóreas, utilizados por diversas espécies da fauna silvestre.

Please read the abstracts included at the beginning of chapters 2 to 5, of this document / Dissertation (MSc)--University of Pretoria, 2007. / Zoology and Entomology / MSc / Unrestricted

Orientador: Eliana Regina Forni Martins / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T09:37:20Z (GMT). No. of bitstreams: 1 Nasario_JoaoPauloSardin_M.pdf: 1858989 bytes, checksum: 1fd7e7dcb1a5473c4ff7fb12d1cd1a15 (MD5) Previous issue date: 2014 / Resumo: Tradicionalmente incluso na extinta família Bombacaceae, Pseudobombax Dugand pertence à subfamília Bombacoideae, Malvaceae sensu lato. Abrange cerca de 29 espécies, das quais 16 ocorrem em território brasileiro e nove são endêmicas. No Brasil, a maioria das espécies é encontrada no sudeste, planalto central e nordeste. As espécies possuem considerável valor comercial, por serem utilizadas no mundo todo, principalmente na ornamentação e arborização urbana. Estudos sobre o sistema reprodutivo e citogenéticos são raros para o gênero. Com este trabalho, objetivou-se o estudo da biologia floral e reprodutiva, assim como a análise cariotípica de três espécies de Pseudobombax da região sudeste do Brasil. As espécies de Pseudobombax são importantes fontes de pólen e néctar para seus visitantes florais, especialmente por florescerem na estação seca. Algumas diferenças foram observadas entre os períodos de floração e frutificação durante os dois anos de estudo, as quais podem estar relacionadas a diferentes quantidades de chuva antes do início da floração. As flores apresentam antese crepuscular/noturna, com características que se encaixam na síndrome da quiropterofilia. As flores de P. tomentosum são significativamente diferentes das demais espécies (maior comprimento da flor, das pétalas, do ovário e do cálice), porém a forma e o indumento dos frutos é a principal característica que podemos utilizar para separar taxonomicamente as três espécies. Os estudos reprodutivos das três espécies evidenciaram alta porcentagem de fecundação cruzada, indicando alogamia. A eficácia reprodutiva manteve-se alta, confirmando a necessidade de polinização cruzada e, consequentemente, de seus polinizadores. As análises citogenéticas mostraram contagens inéditas, com 2n=88 para Pseudobombax sp. (nova) e P. tomentosum e 2n=84 para P. grandiflorum. O número básico sugerido para as espécies de Pseudobombax é x=44. Foi confirmado mais de um número cromossômico no gênero, o que sugere a derivação por disploidia, decorrente de possíveis rearranjos cromossômicos. Pseudobombax sp. (nova) e P. grandiflorum, espécies muitas vezes confundidas entre si, possuem números cromossômicos diferentes (2n=88 e 2n=84, respectivamente) sendo este um caráter adicional importante na separação taxonômica das duas espécies. O bandamento CMA/DAPI evidenciou um padrão conservado dentro do gênero, com seis bandas CMA+ nas três espécies. Os valores métricos dos cromossomos das espécies em estudo indicaram um comprimento do complemento cromossômico pequeno, nas quais o menor tamanho cromossômico foi de 0,3 µm em P. grandiflorum e o maior foi de 3,5 µm em P. tomentosum. O diferente número cromossômico, bem como algumas características morfológicas florais e do fruto podem ser utilizadas na separação taxonômica das três espécies de Pseudobombax em estudo, evidenciando assim a existência de uma nova espécie para o gênero / Abstract: Traditionally included in the extinct family Bombacaceae, Pseudobombax Dugand belongs to the Bombacoideae subfamily, Malvaceae sensu lato. Composed by about 29 species, of which 16 occur in Brazilian territory and nine are endemic. In Brazil, most species are found in the southeast, northeastern and central plains. Species have considerable commercial value, for being used worldwide, especially in ornamentation and urban forestry. Studies on the reproductive system and cytogenetics are rare for the genus. This work aimed to study the floral and reproductive biology, as well as analysis of karyotype of three species of Pseudobombax from southeastern Brazil. The Pseudobombax species are important sources of pollen and nectar for their floral visitors, especially by flourishing in the dry season. Some differences were observed between the periods of flowering and fruiting during the two years of study, which may be related to different amounts of rainfall before flowering. The flowers have crepuscular/nocturnal anthesis, with features that fit in the chiropterophily syndrome. The flowers of P. tomentosum are significantly different from the other species (greater length of the flower petals, the ovary and the cup), but the shape and indumentum of the fruit is the main feature that we can use to separate the three species taxonomically. Reproductive studies of the three species showed a high percentage of outcrossing, indicating outcrossing. The reproductive efficiency remained high, confirming the necessity of cross-pollination and, therefore, their pollinators. Cytogenetic analysis showed unprecedented chromosome counts, with 2n=88 to Pseudobombax sp. (new) and P. tomentosum and 2n=84 for P. grandiflorum. The basic chromosome number suggested to Pseudobombax is x=44. We confirmed more than one chromosome number in the genus, which suggests derivation by disploidy, due to possible chromosomal rearrangements. Pseudobombax sp. (new) and P. grandiflorum, species often confused with each other, presented different chromosome numbers (2n=88 or 2n=84 , respectively) which is an important taxonomic character for the separation of the two species. The CMA/DAPI banding showed a conserved pattern within the genus, with six CMA+ bands in all species. The metric values of the chromosomes of the species under study indicated a small chromosomal complement length, wherein the smallest chromosome size was 0.3 µm in P. grandiflorum and the largest was 3.5 µm in P. tomentosum. The different chromosome numbers, as well as some floral and fruit morphological characteristics can be used for taxonomic separation of the three Pseudobombax species under study Pseudobombax, thus revealing the existence of a new species for the genus / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal

Although Mauritia flexuosa (Arecaceae) plays a pivotal role in the ecology and economy of the Amazon, and occurs in a variety of habitats, little is known about the influence of habitat on the reproductive biology of this palm. My dissertation focuses on the reproductive biology of M. flexuosa in three habitats in Roraima, Brazil: undisturbed forest, undisturbed forest-savanna ecotone, and savanna disturbed by plantations of the exotic tree, Acacia mangium. First, I calculated sex ratios and linked precipitation patterns with phenology. Sex ratios were female-biased. Precipitation was negatively associated with flowering, and positively associated with fruiting. Habitat appears to have no significant influence on phenology of M. flexuosa, although short-term climate variation may affect phenology of this species. Second, I examined floral biology, observed floral visitors, and performed exclusion experiments to determine the pollination system of M. flexuosa. Fruit set did not differ significantly between the visitor exclusion treatment and the control, but was significantly lowest in the wind + visitor exclusion treatment, suggesting that this dioecious palm is anemophilous, independent of habitat. Third, I identified the abiotic and biotic factors explaining variation in fruit mass, seed mass, seed number per fruit, and total fruit yield among habitats. Soil moisture and flooding during the wet season were the best predictors of fruit and seed output. The number of leaves, diameter at breast height, and height were all accurate predictors of reproductive output, but crown volume did not accurately predict fruit yields. Results re-evaluate traditional assumptions about wind-pollination in the tropics, and highlight abiotic and biotic factors responsible for variation in reproductive output of M. flexuosa, with implications for effective management of this palm. Finally, I interviewed harvesters and vendors to document the traditional knowledge and market dynamics of the fruit of M. flexuosa, buriti. Traditional knowledge corroborated results from scientific studies. Vendors argued that the price of buriti must increase, and must fluctuate with varying supply. With appropriate economic incentives to vendors/harvesters, Roraima may expand its market infrastructure for buriti, effectively stimulating the regional economy and practicing sustainable harvesting.

<p>The need to protect size and age structures from selective harvest in order to maintain sustainable fish stocks has been emphasized in recent literature. The Big Old Fat Fecund Female Fish (BOFFFF) hypothesis has been influential in discussions of changing stock management strategies, and postulates that larger, older females have a disproportionate input into stock recruitment due to physiological advantages. In this study, we utilize a meta-analysis approach to test the assumption of the BOFFFF hypothesis, that larger female fish produce larger eggs and more viable offspring, at a broad scale. Following the meta-analyses, we assess whether larger females from a subset of studies use their gonadal investment more efficiently than small females. From our meta-analyses, we found positive, significant intraspecific relationships between female size and egg size. Moreover, we found positive associations between egg size and offspring viability (offspring size and survival). However, we found in a subset of studies that although proportional survival of offspring often increases with egg size, females that produced larger eggs yielded fewer surviving offspring per unit gonadal investment. This reduced efficiency in reproductive investment is a product of the trade-off between egg size and fecundity. We conclude that although larger females may appear to produce more viable individual offspring, their input to stock recruitment, according to total stock gonadal biomass, may not be disproportionate, as stated by the BOFFFF hypothesis. However, we did not account for whether the benefits of maternal effects extend beyond the larval stage.</p><p>The theory of optimal egg size implies that fish trade off between fecundity and individual gonad investment according to their environment. Past interspecific studies suggest that in general, fishes in large, marine systems produce smaller eggs than those in small, freshwater systems. This study aims to compare egg size intraspecifically among small and large systems. In particular, we focus on populations from the Laurentian Great Lakes, which exhibit similar broadscale physical processes as marine systems, and smaller inland lakes (<1,000 ha), whose ecosystems contain many of the same species. In 2018 and 2019, we collected egg samples from spawning walleye (<i>Sander vitreus</i>) and yellow perch (<i>Perca flavescens</i>) in both inland lake and Great Lake populations. From each female, we recorded total lengths, and measured average diameters of ten eggs. Using ANCOVA models, we compared mean length-adjusted egg diameters intraspecifically among populations of both species. For both walleye and yellow perch, we found that females from inland lakes produced larger mean length-adjusted egg diameters than those of the Great Lakes. This pattern was particularly evident for yellow perch, whereas for walleye the pattern was relatively weak, potentially due to stocking eroding population-specific selection for egg size. These intraspecific patterns are consistent with cross-system interspecific variation in fish egg size.</p>

<p>Plants are used as a primary food source by humans. Some plants produce edible roots or leaves, but most crops used today are grown to harvest their nutrient-rich seeds which are a product of double fertilization in flowering plants. </p> <p>Cell-cell recognition, adhesion, and fusion are widespread phenomena in many biological processes, where fertilization is an exemplary process. Many players have been identified to mediate sperm-egg fusion in both animals and plants. Interestingly several of these components were shown to be structurally and functionally conserved across kingdoms. In animals Tetraspanins act as facilitators of sperm-egg fusion. Tetraspanins are known to associate in clusters in the plasma membrane of cells, where they recruit diverse signaling proteins, forming the so called Tetraspanin-enriched microdomains (TEMs). TEMs are therefore recognized as major signaling platforms mediating specific cellular processes in the plasma membrane of cells. Two <i>Arabidopsis</i>-expressed tetraspanins, <i>TET11</i> and <i>TET12</i>, are highly expressed in the sperm cells (SCs), however their function in fertilization are unknown. Using fluorescence microscopy, we quantified the expression of TETs in SCs and found evidence for the existence of a Tetraspanin-enriched microdomain (TEM) at the SC-SC adhesion interface. Sperm cell factors which are necessary for fertilization were found to accumulate at the TEM, suggesting that plant SC TEMs may function as protective platforms for fertilization factors. Sperm-expressed TETs directly interact with members of a novel, plant-specific family of unknown proteins, <i>DMP8/9</i>. DMP8/9 function as negative regulators of SC-SC adhesion and are required for double fertilization. Structural and functional analysis suggest that these two proteins may perform unique functions as membrane remodelers in SCs. In addition, we provide evidence of a new GEX2 function as a SC-SC adhesion factor and potential partner of TET-DMP complexes at the SC-SC interface.</p>

<div> <p>Mammalian embryos undergo a dramatic amount of epigenetic remodeling during the first week of development to establish the correct epigenetic status to support the developmental program. SWI/SNF chromatin remodeling complexes are multi-subunits complexes and utilize energy from ATP hydrolysis to modify chromatin structure non-covalently. The collection of subunits determines the identity of a given SWI/SNF chromatin-remodeling complex, directs its activity, and dictate where that complex will act. The aims of this study were to 1) determine the requirement of SNF5, a SWI/SNF core subunit found in BAF and PBAF complexes during preimplantation porcine embryo development, 2) determine the requirement of BRD7, a PBAF complex-specific subunit during preimplantation porcine embryo development, and 3) investigate the role of <i>CDH1</i>, a downstream gene regulated by ARID1A, another subunit found exclusively in BAF complexes, in cleavage stage porcine embryos. Our results indicate that the differential requirement for each subunit during early embryo development. Depletion of different subunits results in embryo arrest at distinct developmental stage. Together, our data suggest the SWI/SNF chromatin remodeling complexes are necessary for proper porcine embryo development and this requirement is associated with the composition of the complex.</p> </div> <br>

The Piceance Basin in western Colorado has undergone a drastic increase in oil and gas development over the last two decades. This increase has escalated concerns about the effects of development on the Basin’s flora and fauna, especially the rare plant community. Potential impacts from oil and gas development on rare plants may be found through decrease in plant habitat or by a decrease in plant reproductive success through changes to important pollinator communities. Here, we observed the pollinator community on two rare mustard plants, Physaria congesta and Physaria obcordata (Brassicaceae), both listed as threatened by the US Fish and Wildlife Service (Federal Register 55 FR 4152). We studied a series of questions concerning the pollinator community important to each Physaria species. The experiments were conducted in the spring of 2010 and 2011 during the blooming season of each rare Physaria. We investigated the effect of oil and gas development on the pollinator community by evaluating abundance, diversity, behavior, and foraging rates along a distance gradient from roadsides. This study also examines plant fecundity to determine the extent of pollinator efficiency across the same distance gradient from roadsides. Additionally, we examine nesting success of pollinators within plant populations, as well as around natural gas wellpads. Further, we conduct a breeding system and cross pollination study on P. congesta to determine the importance of pollination services for reproduction. To determine overall pollinator community changes around other development types we sampled pollinators around wellpads. Our data supports the null hypothesis, suggesting that at this time oil and gas development may have little to no impact on the pollinator community abundance. The analysis conducted may not have been able to detect changes in the community, due to a small sample size of pollinators collected. Bee pollinators may forage on a few or many floral resources. Here, we account for the ancillary foraging resources of P. congesta and P. obcordata pollinators by identifying pollen removed from bees collected on rare Physaria. This specific community of plants may require conservation in addition to the rare plants, to assist in maintaining the pollinator community.

Tesis por compendio / [ES] Desde el origen de los cítricos, hibridaciones naturales ancestrales, espontáneas o de cultivo a lo largo de miles de años, han ocasionado fenómenos de mezcla que han determinado la complejidad de la biología reproductiva de los cítricos cultivados hoy en día. El objetivo global de esta tesis doctoral es aumentar el conocimiento sobre diferentes aspectos reproductivos que son cruciales para la mejora y propagación de los cítricos y su interacción con las condiciones ambientales. El primer objetivo de esta tesis doctoral ha sido el análisis del efecto de la temperatura en la fase progámica de los cítricos. Hemos comprobado que las temperaturas altas redujeron el tiempo que necesitaban los tubos polínicos para llegar a los óvulos y también aceleraron la degeneración del pistilo, mientras que las bajas temperaturas produjeron los efectos opuestos. Sin embargo, los tubos polínicos pudieron llegar a los óvulos en todos los cruces estudiados. Es interesante señalar que observamos por primera vez en cítricos tanto la germinación del polen como el crecimiento del tubo polínico a 10ºC. Las mandarinas representan el 24% de la producción total de cítricos y la ausencia de semillas se valora como criterio de calidad en el mercado de la fruta fresca. La aptitud partenocárpica (AP) es la clave para la producción de frutos sin semillas cuando se combina con la autoincompatibilidad (AI) o la esterilidad. El segundo objetivo de esta tesis doctoral fue evaluar AP y AI para variedades de mandarina con características relevantes como progenitores para la mejora genética de mandarinas sin semillas. Para ello, desarrollamos un protocolo eficiente basado en la emasculación, la autopolinización manual y la polinización cruzada manual. Se observaron seis comportamientos diferentes entre las nueve variedades analizadas. Subrayar que más allá de la importancia crítica de la AI para la producción de frutos sin semillas, la AI es un obstáculo para los programas de mejora genética basados en hibridación, ya que reduce las posibilidades de cruzamiento. Esta circunstancia motivó el planteamiento del tercer objetivo de esta tesis doctoral. Dicho objetivo fue comparar la eficiencia de la ruptura de la reacción de AI por tres factores previamente identificados en otras especies: estrés por temperatura, polinización de yemas florales y poliploidización. Los tres métodos tuvieron éxito en la obtención de plantas autofecundadas, y la polinización de yemas florales resultó ser el método más eficiente. La selección asistida por marcadores (MAS) permite la selección de genotipos en la etapa de plántula, lo que la convierte en una herramienta poderosa, especialmente en especies de árboles con un largo período juvenil, como es el caso de los cítricos. El cuarto objetivo de esta tesis doctoral se centró por tanto en el desarrollo de marcadores SNPs asociados a poliembrionía y esterilidad masculina. Mediante estudios exhaustivos de asociación genética, identificamos una región genómica en el grupo de ligamiento 1 asociado con poliembrionía y una región genómica en el grupo de ligamiento 8 asociado con NPG. Se desarrollaron marcadores SNP cercanos a genes que tienen funciones relacionadas con la esterilidad masculina y con la poliembrionia para las dos regiones genómicas. Esta tesis doctoral proporciona nuevos conocimientos sobre la biología reproductiva de los cítricos y la influencia de la temperatura en ella. El conocimiento generado permitirá implementar de manera más eficiente los programas de mejora genética, particularmente aquellos destinados a la obtención de variedades sin semillas. Además, este conocimiento podrá utilizarse para ayudar en la respuesta a algunos de los desafíos más apremiantes que plantea el escenario actual de calentamiento global. / [CA] Des de que es van originar els cítrics, hibridacions naturals ancestrals, espontànies o de conreu, al llarg de milers d'anys, han ocasionat fenòmens de mescla que han determinat la complexitat de la biologia reproductiva dels cítrics actualment conreats. L'objectiu global d'aquesta tesi va ser augmentar el coneixement de diferents aspectes reproductius dels cítrics ¿especialment en la seua interacció amb les condicions ambientals¿ crucials per a la seua millora genética i reproducció, El nostre primer objectiu ha estat l'anàlisi de l'efecte de la temperatura en la fase progàmica dels cítrics. Hem comprovat que les temperatures càlides redueixen el temps necessari per arribar als òvuls pels tubs de pol·len i que també acceleren la degeneració del pistil; mentre les temperatures fredes van produeixen els efectes contraris. No obstant això, els tubs pol·línics van poder arribar als òvuls en totes les creus estudiades. Curiosament, vam observar per primera vegada als cítrics tant la germinació del pol·len com el creixement del tub pol·línic a 10ºC. Les mandarins representen el 24% de la producció total de cítrics i l'absència de llavors és un criteri de qualitat crucial en el mercat de la fruita fresca. La capacitat partenocàrpica (PA) és la clau per a la producció de fruites sense llavors quan s'acobla a l'autoincompatibilitat (SI) o l'esterilitat. El segon objectiu d'aquesta tesi doctoral va ser avaluar PA i SI per a varietats de mandarines amb característiques rellevants com a progenitors per a la millora genètica de mandarines sense llavors. Amb aquesta finalitat, hem desenvolupat un protocol eficient basat en l'emasculació, l'autopol·linització manual i la pol·linització creuada manual. Es van observar sis comportaments diferents entre les nou varietats analitzades. Subratllar que, enllà de la importància crítica del SI en la producció de fruites sense llavors, el SI és alhora un obstacle per als programes de millora basats en la hibridació, ja que redueix les possibilitats d'encreuament. Aquesta circumstància va motivar el plantejament del tercer objectiu d'aquesta tesi doctoral. Aquest objectiu va ser comparar l'eficiència de la ruptura de la reacció SI per tres factors identificats prèviament en altres espècies: estrès per temperatura, pol·linització de rovells florals i poliploidització. Els tres mètodes van tenir èxit en l'obtenció de plantes autofecundades, i la pol·linització de rovells florals va resultar ser el mètode més eficient. La selecció assistida per marcadors (MAS) en l'etapa de plàntules permet la selecció de genotips diana, la qual cosa la converteix en una eina potent, especialment en espècies d'arbres amb període juvenil llarg, com els cítrics. El quart objectiu d'aquesta tesi doctoral se centra en el desenvolupament de marcadors SNPs associats a la poliembriona i l'esterilitat masculina. Estudis exhaustius d'associació genètica, vam identificar una regió genòmica al grup de lligament 1 associada a la poliembrionia i una regió genòmica al grup de lligament 8 associada amb NPG. Es van desenvolupar marcadors SNP estretament relacionats amb gens implicats per a les dues regions genòmiques. Aquesta tesi doctoral proporciona nous coneixements sobre la biologia reproductiva dels cítrics i la influència de la temperatura sobre ella. El coneixement generat permetrà implementar de manera més eficient els programes de millora genètica, especialment aquells destinats a l'obtenció de varietats sense llavors. A més, aquest coneixement es podrà utilitzar en la complexa resposta a alguns dels reptes més urgents que planteja l'escenari actual d'escalfament global. / [EN] Since the origin of citrus, ancestral natural hybridizations, thousands of years of cultivation and admixture phenomenon have resulted in the complexity of the reproductive biology of today's cultivated citrus. The global objective of this PhD was to increase our knowledge on different reproductive aspects that are crucial for citrus breeding and propagation and their interaction with environmental conditions. Temperature in the progamic phase is critical for the success of plant sexual reproduction. Pollen grain germination, stigmatic receptivity and pollen tube growth are the main components of this phase. The analysis of temperature effect on the progamic phase of citrus was our first objective. Using three compatible crosses within the Citrus genus, we evaluated, with this method, the effect of four temperature regimes in every process during the progamic phase. Warm temperatures reduced the time needed by pollen tubes to reach the ovules and also accelerate pistil degeneration while cold temperatures produced the opposite effects. However, pollen tubes were able to reach the ovules in all crosses studied. Interestingly, we observed for the first time in citrus both pollen germination and pollen tube growth at 10ºC. Mandarins account for 24% of total citrus production and seedlessness is a crucial quality criterion for the mandarin fresh fruit market. Parthenocarpic ability (PA) is the key for seedless fruit production when it is coupled with self-incompatibility (SI) or sterility. The second objective of this PhD dissertation was to evaluate PA and SI for mandarin varieties with relevant characteristics as parents for seedless mandarin breeding. For this purpose, we developed an efficient protocol based on emasculation, hand self-pollination and hand cross-pollination. Pollen performance was analysed by histological observations, together with fruit set and seed production. Six different behaviors were observed among the nine varieties analysed. Beyond the critical importance of SI for seedless fruit production, SI is an obstacle for breeding programs based on hybridization as it reduces crossing possibilities. The third objective of this PhD dissertation was to compare the efficiency of the SI reaction breakdown by three factors previously identified in other plant species: temperature stress, bud pollination and polyploidization. The three methods were successful in recovering selfed plants, and bud pollination was the most efficient approach. Chromosome doubling was also efficient, but involved developing tetraploid plants. Cold temperature stress allowed us to obtain a few diploid selfed plants. However, this method proved much more complex to apply than bud pollination in specific breeding programs. Marker-assisted selection (MAS) allows the selection of target genotypes at the seedling stage, making it a powerful tool, especially in tree species with long juvenile period, such as citrus. The 4th objective of this PhD dissertation focuses on the development of SNPs markers associated with polyembryony and male sterility. Through genetic association studies, we identified a genomic region in linkage group 1 associated with polyembryony and a genomic region on linkage group 8 associated with NPGA. SNP markers closely linked with implied genes were developed for the two genomic regions. Overall, this PhD dissertation provides new insights into citrus reproductive biology and the influence of temperature on it. The knowledge generated will allow to implement breeding programs more efficiently, particularly those aimed at obtaining seedless varieties. This knowledge can eventually be used to respond to some of the most pressing challenges posed by the current global warming scenario. / Montalt Resurrección, R. (2023). Assessment of Citrus Reproductive Biology for Seedless Mandarin Production and its Interaction with Temperature [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/193856 / Compendio