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Thesis (Ph. D.)--University of Hong Kong, 1967.

The mutualism between the dioecious Ficus tinctoria and its pollinators was studied at Hsitzewan, Kaohsiung. I investigated the phenology of F. tinctoria from December 2004 to May 2006. Wasps trapped in sticky boards were recorded from April 2005 to May 2006. The average diameter of receptive figs (B phase) of female F. tinctoria was significantly different from that of functional male trees (P < 0.01), but both with similar coloration. The durations of pre-receptive figs (A phase) through wasp- releasing figs (D phase) or mature figs (E phase) in F. tinctoria were slight longer in winter and spring (8.3-8.8 weeks) than in summer and autumn (6.8-7.0 weeks). The receptive figs were asynchronous both within-tree and among-trees. The receptive figs occurred in every month of 2005 and without seasonality. There were considerable overlaps (82.6%) in the receptive figs between functional male and female trees. The frequency of tender leaf phase of F. tinctoria was positively correlated with local rainfall and temperature, but the frequency of leaf falling phase was negatively correlated with them. The frequency of receptive figs of female trees was only positively correlated with rainfall, and the frequency of their interforal figs (C phase) were both negatively correlated with rainfall and temperature. Fig production of functional male F. tinctoria was not correlated with rainfall and temperature. There are five species of fig wasps, including one species of pollinator (Liporrh opalumgibbosae), one species of Sycoscapter, two species of Philotrypesis, and one species of Neosycophila. No significant difference was found in the average number of 4 species of fig wasps from D phase figs (6.3 pollinators, 8.8 Philotrypesis sp.1, 5.7 P. sp.2, and 5.7 Sycoscapter sp.1 per fig). In addition, one species of Sycophila (Eurytomidae) was also found inside figs of F. tinctoria. The coordination between D phase figs of male F. tinctoria to its B phase was iii 26.2%, which was similar to the coordination of it to B phase of female trees (29.5%). However, more pollinators arrived on male trees than that on female trees. The coordination between pollinators and B phase figs of male trees (43.0%) was higher than that of female trees (14.6%). Fig-pollinator mutualism in F. tinctoria is probably maintained by its asynchronous phenology, and aseasonal changes of the receptive figs. Seed production at female trees can be maintained by a small size of pollinator populations.

La spéciation et la diversification sur les iles sont des processus évolutifs tirés par de nombreux facteurs tels qu’histoire géologique et complexité topographique. Réciproquement, l’histoire évolutive d’une espèce contribue à expliquer ses traits biologiques et écologiques actuels. J’ai cherché à analyser ces patrons et processus à travers un système modèle présent à travers toutes les régions tropicales du monde : les Ficus et leurs insectes pollinisateurs (Hymenoptera : Chacidoidea). Plus particulièrement je me suis focalisée sur les Ficus du sous genre Sycomorus et leurs pollinisateurs, les insectes du genre Ceratosolen. Les deux objectif principaux de ma thèse ont été de : (1) étudier l’histoire biogéographique des espèces de Ceratosolen des Philippines à partir des reconstructions phylogénétiques et (2) étudier quelques aspects de la biologie et de l’écologie de ces espèces et de les relier à leur histoire évolutive. Pour l’objectif 1, nous montrons que, comme la plupart des biota des Philippines, les Ceratosolen sont arrivés du sud par Palawan ou par l’archipel de Sulu, à de multiples reprises. Il semble que l’histoire géologique, les bras de mer profonds et les changements de niveau des mers du Pléistocène ont une valeur explicative faible pour comprendre la distribution et la diversification des groupes d’espèces. Les facteurs importants seraient plutôt la complexité topographique des iles, les distances entre iles, la capacité intrinsèque de dispersion des insectes et la spécialisation écologique. Pour l’objectif 2 nous avons étudié les traits suivants : la modification des pattes arrière, la durée de vie, l’activité journalière, la structuration génétique spatiale et la perception des odeurs de figues réceptives. Nous montrons que les pattes postérieures modifiées de C. corneri ont des propriétés hydrophobes plus fortes que celles, non modifiées, de son proche parent, C. jucundus. Le caractère hydrophobe de ces pattes permet aux males de C. corneri de respirer même submergé dans du liquide dans les figues. Cette adaptation est probablement le résultat de la sélection sexuelle car ces males peuvent émerger plus tôt de leurs galles pour féconder les femelles. Nous montrons ainsi comment un trait de la figue, la quantité de liquide, contraint la morphologie et le comportement du pollinisateur. Par ailleurs nous documentons plusieurs cas de coexistence locale de plusieurs espèces de pollinisateurs associées à F. septica. Dans un site nous montrons que les deux espèces de pollinisateurs diffèrent par leur durée de vie mais débutent leur activité en même temps. De plus, F. septica et ses clades de pollinisateurs noirs présentaient une structure géographique similaire. Ce patron a pu apparaitre dans le contexte de barrières géographiques fortes, menant à l’isolement, à l’adaptation locale et finalement, à la co-diversification. Nous montrons que la coexistence de pollinisateurs a probablement été rendue possible par un déplacement initial de caractère suivi d’une extension d’aire. Finalement, nous fournissons des éléments montrant que les variations géographiques d’odeurs de figues réceptives ne limitent pas l’expansion géographique des insectes pollinisateurs. Ceci est confirmé par nos résultats sur la gamme d’odeurs perçues par les insectes. Nous montrons que cette perception était fortement dépendante des stimuli rencontrés. Ainsi nous voyons une convergence des odeurs perçues entre insectes partageant un même hôte. Ceci est une démonstration de la plasticité évolutive du système de perception des odeurs des insectes. Ainsi notre travail explore des aspects historiques et biologiques de l’ensemble des Ceratosolen des Philippines, avec une focalisation sur la diversification en cours dans le système Ficus septica-insectes associés. La suite du travail abordera les moteurs biologiques et les processus biologiques tels que la co-spéciation ou le partage de pollinisateurs que nous avons documentés ici. / Speciation and diversification in islands are evolutionary processes that are driven by many factors such as geological history and topographic complexity. In turn, the evolutionary history of a species contributes to explaining its present biological and ecological traits. In wanting to investigate these patterns and processes, I chose a model system that is present throughout the tropical areas of the world: the figs (genus Ficus) and fig wasps (Hymenoptera: Chalcidoidea). Specifically, I focused on a subgroup of this model system: the subgenus Sycomorus figs and their associated pollinators, the Ceratosolen wasps. The two main objectives of this thesis were: (1) to investigate the biogeographic history of the Philippine Ceratosolen species using phylogenetic tree reconstructions and (2) to investigate certain biological and ecological traits of Philippine Ceratosolen species and to relate these traits to their evolutionary history. For Objective 1, we have shown that, like most Philippine biota, Ceratosolen wasps most likely arrived from the south of the Philippines via Palawan or the Sulu archipelago. It is likely that geological history, deep-water barriers and Pleistocene sea-level changes were not major factors explaining the distribution and diversification of these species groups. They are most likely affected by other factors such as island topographic complexity, distances between islands, intrinsic wasp dispersal ability and ecological specialization. For Objective 2, we specifically looked at the following wasp traits: hind leg modifications, life span and daily activity, spatial genetic structuring and odour perception. We have shown that male C. corneri modified hind legs were able to repel liquids more than its close relative, C. jucundus, that has unmodified hind legs. The hydrophobicity of these hind legs allows C. corneri male wasps to respire even when they are submerged in fig liquid. This adaptation is probably a response to sexual selection because these male wasps now have the ability to emerge earlier to search for mates. We have thus shown how fig functional traits, i.e. amount of fig liquid, can constrain fig wasp morphology and behaviour. Moreover, in the F. septica system, we documented several instances of multiple pollinator species associating with F. septica. In one site, these two pollinator species differed in life span, but are active the same time. Also, F. septica and its black pollinator clades exhibited similar geographic structuring. This could originally be due to strong geographic barriers leading to isolation, local adaptation, and finally co-diversification. We also show the co-existence of pollinating species in an area which probably had been brought about by initial character displacement and subsequent range expansion. Lastly, we provide evidence that receptive fig odours do not constrain the species specificity of the interactions. This was further supported by our results on the range of wasp odour perception. We saw that odour perception in fig wasps is highly dependent on the olfactory stimuli. Convergence in odour perception was seen when wasps shared hosts and divergence was demonstrated when wasp species were constrained to respond to different scent profiles. This is remarkable evidence of the evolutionary plasticity in the insect odour perception system. Thus, this work explored aspects of the history and biology of Philippine Ceratosolen, as a whole, with a focus on the current on-going diversification processes in the Ficus septica-wasp system. Future work should look at the biological drivers of evolutionary processes such as co-speciation and pollinator sharing that we have documented here.

A distinct pattern of obligate mutualism exists between fig tree hosts and their pollinating fig wasps. Normally one section or subsection of fig tree hosts is associated with one fig wasp genus. In general, each species is pollinated by a specific fig wasp species. This led to the hypothesis that the fig wasp and fig tree lineages diverged simultaneously. African fig wasps pollinating hosts of the Galoglychia section frequently break the normal one fig wasp species-to-one host species ratio. The phylogeny for these species was reconstructed using three DNA segments and compared to the morphological classification of their Ficus hosts. Pollinator genera were monophyletic for all analyses, however, the relative positioning of genera was inconsistent. Analyses suggest frequent host jumps between fig trees and fig wasps. Fig wasps of the genus Alfonsiella that pollinate Ficus craterostoma, Ficus stuhlmannii and Ficus petersii are morphologically similar in South Africa. Based on host association, genetic differentiation for this group was investigated. Molecular data indicated that the pollinator of F. craterostoma is a good species, while the F. stuhlmannii and F. petersii pollinators were genetically indistinguishable. Based on molecular data and morphological re-evaluation, a new Alfonsiella species is described, Alfonsiella pipithiensis sp. n. A key to all described species of Alfonsiella is provided. In order to resolve the population genetic differentiation of pollinating fig wasp species in South Africa, Platyscapa awekei was used as a model species. A few studies indicate that pollinating fig wasps can disperse between 30 and 55 kilometers. However, a recent study on two P. awekei populations in South Africa reported an FST value of 0.011, indicating that pollinators disperse approximately ten times further. This study aims to confirm these results with more detailed sampling of populations. In addition, possible temporal differentiation was tested for the South African population. Six microsatellite loci were used to detect spatial and temporal genetic differentiation in seven populations (collected from 2004 to 2006) over a 340 kilometer range. Genetic differentiation between sampled populations was low (FST = 0.0055), however, the data suggest stronger temporal genetic isolation than spatial genetic isolation. / Dissertation (MSc (Genetics))--University of Pretoria, 2011. / Genetics / unrestricted

A striking variation in the behaviour of pollinating fig wasps (Agonidae) is the occurrence of male fighting in some species while in others it is completely absent. Fighting behaviour was investigated at two levels. Firstly, the variation in fighting behaviour between the species was used to examine factors that might cause the evolution thereof. Comparisons across species were done using phylogenetic regression. This method takes similarity due to phylogenetic constraints into account when data are compared. Kin selection theory implies that fighting is barred by the high degree of relatedness in competing males. We however find that the relatedness of the males do not have an influence on the evolution of fighting and this finding supports models suggesting that high LMC cancels benefits due to relatedness. Rather, that the only factor having a significant correlation with fighting is the release sex ratio. The release sex ratio and dispersal is also associated. Fighting and dispersal are not expected to have direct influence on each other and the association of both with the release sex ratio imply that this may be an indirect link between these two behaviours. A syndrome where fighting and dispersal is found together is in part explained by the release sex ratio. We conclude that the release sex ratio is the most likely cause of the evolution of fighting behaviour in pollinating fig wasps. The second part of this study deals with the proximal determinants causing fighting, in the males of the species Platyscapa awekei. We show that the sex ratio which, is less female biased than non-fighting pollinator species, rapidly becomes even less female biased as soon as both sexes becomes active. Numerous fights are fought by the males in the female limited environment. The activity of the wasps is shown to be regulated by the gaseous environment, which change from a high to a low CO2 concentration with the construction of an exit hole from the fig. The males of the species P. awekei are inactive, and do not engage in mating or fighting activities, in high CO2, contrasted to males of other species, which are active in this environment. P. awekei females rapidly release once the CO2 level is lowered and mating behaviour is only observed in this environment. The number of female to male encounters of every male decrease as the operational sex ratio becomes less female biased. Male fighting in this species is therefore expected due to the high sex ratio, which is enforced by the increase thereof. We conclude that the physical environment, in this species, affects the mating environment. The resultant reduction in the number of potential mating opportunities therefore escalates fighting between the males. / Dissertation (MSc)--University of Pretoria, 2008. / Genetics / unrestricted

The advent of next generation sequencing technologies has had a major impact on inference methods for population genetics. For example, community ecology studies can now assess species interactions using population history parameters estimated from genomic scale data. Figs and their pollinating fig wasps are obligate mutualists thought to have coevolved for some 75 million years. This relationship, along with additional interactions with many species of non-pollinating fig wasps (NPFW), makes this system an excellent model for studying multi-trophic community interactions. A common way of investigating the population histories of a community's component species is to use genetic markers to estimate demographic parameters such as divergence times and effective population sizes. The extent to which histories are congruent gives insights into the way in which the community has assembled. Because of coalescent variance, using thousands of loci from the genomes of a small number of individuals gives more statistical power and more realistic estimates of population parameters than previous methods using just a handful of loci from many individuals. In this thesis, I use genomic data from eleven fig wasp species, which are associated with three fig species located along the east coast of Australia, to characterise community assembly in this system. The first results chapter describes the laboratory and bioinformatic protocols required to generate genomic data from individual wasps, and assesses the level of genetic variation present across populations using simple summaries. The second results chapter presents a detailed demographic analysis of the pollinating fig wasp, Pleistodontes nigriventris. The inferences were made using a likelihood modelling framework and the pairwise sequentially Markovian coalescent (PSMC) method. The final results chapter characterises community assembly by assessing congruence between the population histories inferred for eight fig wasp species. The population histories were inferred using a new composite likelihood modelling framework. I conclude by discussing the implications of the results presented along with potential future directions for the research carried out in this thesis.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Syconia of fig trees present a diverse interaction with different groups of organisms. In this study we characterized insect community associated with three fig species in the region of Miranda/Abobral, Pantanal Sul matogrossense, obtaining data about species richness and abundance of these insects. We verified the specificity of these insects in regard to hosts and tested whether the size and number of flowers in the syconium determine species richness and abundance of insects in the syconia. We found 31 morpho-species of insects in the syconia of the three hosts. Syconia of Ficus obtusifolia had the highest richness (N = 18) and highest number of species co-occurring in the same syconia. Seven insect species were found sharing hosts. Mean abundance and species richness of insects in syconia of F. obtusifolia were significantly higher than in F. pertusa and F. luschnathiana what was related to the higher volume and number of flowers in the syconia of this fig tree. Our data may help in understanding the diversity and distribution of the insects associated with syconia of fig trees in the neotropical region. Papers that study Ficus insects associated system are important to show how these interactions occur in distinct fig trees and in different localities. / Sicônios de figueiras apresentam uma diversificada interação com diferentes grupos de organismos. Neste estudo, nós caracterizamos a comunidade de insetos associados a três espécies de figueiras na região do Miranda/Abobral, Pantanal Sul matogrossense, obtendo dados sobre a riqueza de espécies e a abundância destes insetos. Verificamos a especificidade destes insetos em relação aos hospedeiros e testamos se o volume e o número de flores dentro do sicônio determinam a riqueza de espécies e a abundância de insetos dentro dos sicônios. Foram encontradas 31 morfo-espécies de insetos nos sicônios das três espécies de figueiras analisadas. Sicônios de F. obtusifolia apresentaram a maior riqueza de espécies (S = 18) e maior número de espécies coocorrendo no mesmo sicônio. Sete espécies de insetos compartilharam hospedeiros. A média da abundância e da riqueza de espécies de insetos co-ocorrendo em sicônios de F. obtusifolia foi significativamente maior do que em F. pertusa e F. luschnathiana, fato que está ligado ao maior volume e número de flores nos sicônios desta figueira. Nossos resultados podem auxiliar no entendimento da diversidade e distribuição de insetos associados a sicônios de figueiras na região Neotropical. Trabalhos que abordam o sistema Ficus insetos associados são importantes para responder como estas interações acontecem em espécies de figueiras distintas e em diferentes localidades.

Obligate nursery pollination mutualisms such as the fig–fig wasp system, with their central plant–pollinator mutualism associated with non-pollinating satellite wasp species, can function as closed system microcosms representative of tritrophic communities. In this system, enclosed inflorescences (syconia) function as sites of seed production, as well as brood-sites for the progeny of herbivorous mutualistic pollinators, non-pollinating gallers and parasitoids of the two. Plant reproductive traits such as inflorescence size (syconium volume) and within-plant phenology (within-tree asynchrony) as can affect inter-species relationships among the three trophic levels in such plant–herbivore–parasitoid systems. Induced or natural variations in such plant traits could influence various direct and indirect effects among the organisms in the community and could even lead to the formation of feedback cycles. Furthermore, changes in the abiotic environment could have major impacts on the biotic associations in the system either by affecting the community members directly, or through their effects on plant reproductive traits. Ficus racemosa with its fig wasp community comprised of a single herbivorous pollinator mutualist, three non-pollinating parasitic gallers and three non-pollinating parasitoids was used as a model to investigate: (1) the role of mutualistic and parasitic fig wasps in affecting within-tree phenology; (2) direct and indirect biotic associations between various groups of fig wasps (pollinators, gallers and parasitoids) and the influence of inflorescence size and within-tree phenology on them; and (3) variations in the reproduction of and the biotic associations between the organisms of the community under variable abiotic climatic conditions. Patterns of plant reproductive phenology are usually considered evolved responses directed at optimizing resource use, pollen receipt/donation schedules and seed dispersal for plant individuals. Within-plant reproductive synchrony or asynchrony can arise due to variation in floral initiation patterns, as well as from localised proximate mechanistic responses to interactants such as pollinators, parasites and herbivores which could affect floral longevity or fruit development time. The investigation was begun by exploring the role of a mutualistic pollinator, and for the first time in a brood-site mutualism, that of parasitic herbivores (gallers) and parasitoids in influencing within-plant reproductive phenology. Since a syconium functions as an inflorescence which develops into a fruit after pollination, investigations were carried out on the impact on syconium synchrony of fig wasps that began their development within the brood site syconium at pre-pollination, pollination, and post-pollination stages via their effects on the development time of individual syconia in Ficus racemosa. We found that syconium initiation patterns were not the only proximate mechanism for within-tree reproductive asynchrony, and that individual syconia (even within a tree) had highly plastic development times dependent on their sizes, pollination time and the species of wasp progeny developing within them. Syconium volume, pollination early in the pollen-receptive phase and presence of early-ovipositing galler progeny reduced syconium development time, whereas the presence of late-ovipositing parasitoid progeny or pollination late in the pollen-receptive phase increased syconium development time. These results suggest an ongoing tug-of-war between syconium inhabitants to modify syconium development times. Parasitic fig wasps pull in different directions to suit their own needs, such that final syconium development times are likely to be a compromise between conflicting demands from developing seeds and from different wasp species. Inter-species relationships among the three trophic levels in plant–herbivore–parasitoid systems can potentially include various direct and indirect effects possibly mediated by induced or natural variations in plant traits. Analysing the seed and fig wasp compositions of microcosm replicates, i.e. individual syconia, shows that besides direct competition for resources and predator–prey interactions, the F. racemosa community also displays exploitative or apparent competition and trait-mediated indirect interactions. Syconium volume and within-tree asynchrony were reproductive plant traits that not only affected plant–herbivore and plant–parasitoid associations, but also possibly modified herbivore–herbivore and herbivore–parasitoid interactions. Our results also indicated that the reciprocal effects of higher trophic level fauna on plant traits (and vice versa) within this system drive a positive feedback cycle between syconium inhabitants and within-tree reproductive asynchrony. In the F. racemosa system, abiotic environmental factors could affect the reproduction of mutualistic pollinators, non-mutualistic parasites and seed production via seasonal changes in plant reproductive traits such as syconium volume within-tree asynchrony. Temperature, relative humidity and rainfall defined four seasons: winter; hot days, cold nights; summer and wet seasons. Syconium volumes were highest in winter and lowest in summer, and affected syconium contents positively across all seasons. Greater transpiration from the nurseries was possibly responsible for smaller syconia in summer. The 3–5°C increase in mean temperatures between the cooler seasons and summer reduced fig wasp reproduction and increased seed production nearly two-fold. Yet, seed and pollinator progeny production were never negatively related in any season confirming the mutualistic fig–pollinator association across seasons. Parasites affected seed production negatively in some seasons, but had a surprisingly positive relationship with pollinators in most seasons. While within-tree reproductive phenology did not vary across seasons, its effect on syconium inhabitants varied with season. In all seasons, within-tree reproductive asynchrony affected parasite reproduction negatively, whereas it had a positive effect on pollinator reproduction in winter and a negative effect in summer. Seasonally variable syconium volumes probably caused the differential effect of within-tree reproductive phenology on pollinator reproduction. Within-tree reproductive asynchrony itself was positively affected by intra-tree variation in syconium contents and volume, creating a unique feedback loop which varied across seasons. Therefore, nursery size affected fig wasp reproduction, seed production and within-tree reproductive phenology via the feedback cycle in this system. Climatic factors affecting plant reproductive traits can cause biotic relationships between plants, mutualists and parasites to vary seasonally and must be accorded greater attention, especially in the context of climate change.

This thesis explores the role mutualist pollinators and their symbionts play in the genetic structuring and speciation of their host plants along an elevational gradient in Papua New Guinea. Using the fig and fig-wasp mutualism as a model system, we employed high-throughput sequencing techniques to explore fine-scale population genomics of both fig and wasps along their elevational range. We found there to be clear lowland and highland clustering of tree populations along the gradient, often with a mid-elevation contact zone. In the case of the pollinating wasps, we retrieved the same clustering except in this case, the genetic difference between clusters was high enough as to consider them as separate species. This result supports evidence from other studies challenging the cospeciation paradigm of one wasp species per fig species. In addition, we explore ecological traits which may promote, or at least, maintain, reproductive isolation between fig (sub)species along with behavioural preference tests from pollinating wasps. In order to further investigate the mechanisms promoting wasp speciation along the gradient, we describe Wolbachia infection status as well as strain type. Wolbachia-induced cytoplasmic incompatibility (CI) is often invoked as a possible speciation agent since it can rapidly provoke and maintain reproductive isolation between otherwise freely interbreeding insect populations. Finally, we explore non-pollinating fig wasp (NPFW) diversity along the gradient for a subset of our focal species. Our study reveals that there is a tight relationship between NPFW diversity and host species, and a mid-elevation peak.