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Euphrasia azorica in natural high altitude grassland at the rim of the volcanic crater; insert shows the white two-lipped flower with yellow marking on the lower lip and anthers close to the upper lip. Photos: J. Weissmann, Corvo 2015.
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To investigate whether endangered endemic plants of the Azores are threatened by pollinator limitation, we studied the insect pollinator communities of Azorina vidalii, Euphrasia azorica, Myosotis azorica and Solidago azorica on Corvo Island. We found no evidence for dependence on a specialised pollinator. Instead, we found five to 21 mostly genera...
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... Five tiny scales narrow the entrance to the corolla tube, thereby reducing access for larger insects (Weryszko-Chmielewska 2003). Like in many other species of the genus, self-pollination probably plays a certain role in this species despite its very showy attractive inflorescences (Robertson & Lloyd 1991). The second species, Euphrasia azorica ( Fig. 3), Orobanchaceae, is also endemic to the western group (Yeo 1973). It is an annual species (Vitek 2015) found in steep slopes, cliffs and waterfalls at 500 to 800 m altitude. Its bilaterally symmetric white flowers with yellow spots are nototribic, i.e. place pollen on the back of the insect. Like in most large- flowered species of ...
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... This is because generalist insect-pollinators are not selective and therefore forage on various flowering plant species. 15,45,46 Being a generalist and over-dominant species, A. mellifera seemed to influence the community structure of the study areas. Furthermore, we found that insect-pollinators in semi-natural areas interacted with a variety of flowering plant species more frequently compared to plants in disturbed areas. ...
Due to inadequate insect-pollinator data, particularly in sub-Saharan African countries like Tanzania, it is difficult to manage and protect these species in disturbed and semi-natural areas. Field surveys were conducted to assess insect-pollinator abundance and diversity and their interactions with plants in disturbed and semi-natural areas in Tanzania's Southern Highlands using pan traps, sweep netting, transect counts, and timed observations techniques. We found that species diversity and richness of insect-pollinators were high in semi-natural areas, and there was 14.29% more abundance than in disturbed areas. The highest plant-pollinator interactions were recorded in semi-natural areas. In these areas, the total number of visits by Hymenoptera was more than three times that of Coleoptera, while that of Lepidoptera and Diptera was more than 237 and 12 times, respectively. Hymenoptera pollinators had twice the total number of visits of Lepidoptera, and threefold of Coleoptera, and five times more visits than Diptera in disturbed habitats. Although disturbed areas had fewer insect-pollinators and fewer plant-insect-pollinator interactions, our findings indicate that both disturbed and semi-natural areas are potential habitats for insect-pollinators. The study revealed that the over-dominant species Apis mellifera could influence diversity indices and network-level metrics in the study areas. When A. mellifera was excluded from the analysis, the number of interactions differed significantly between insect orders in the study areas. Also, Diptera pollinators interacted with the most flowering plants in both study areas compared to Hymenopterans. Though A. mellifera was excluded in the analysis, we found a high number of species in semi-natural areas compared to disturbed areas. Conclusively, we recommend that more studies be conducted in these areas across sub-Saharan Africa to unveil their potential for protecting insect-pollinators and how ongoing anthropogenic changes threaten them.
... For inclusion, we required that both plants of a sib pair were strongly called as outbred (probability > 0.9). Population 4 is not listed because no progeny passed genotyping filters addition, a variety of other insects are known to visit Macaronesian Asteraceae (Weissmann & Schaefer, 2017). Compared to, for example, the Canary Islands, Madeira is noteworthy for the relatively high number of bee species (Fellendorf et al., 1999;Kratochwil, Smit & Aguiar, 2018). ...
... Whether the pollen from multiple plants arrives by a single visitor with pollen from previous visits to other plants (pollen carryover) or by multiple pollinator visits is not known. There are numerous potential biotic pollinators in the Macaronesian archipelagos (Weissmann et al., 2017;Kratochwil et al., 2018), and Madeira, in particular, has a relatively high number of bee species (Fellendorf et al., 1999;Kratochwil et al., 2018). An endemic hoverfly has been recorded visiting T. macrorhiza and T. succulenta on Madeira, and native bees are frequent visitors of various Asteraceae on Madeira (Valido & Olesen, 2010). ...
There have been many studies of morphological and genetic variation in island plant radiations, but few have shown how the mating system has shaped the patterns of variation. In this study, outcrossing rates and paternity in eight populations of the Madeiran endemic Tolpis macrorhiza were estimated using genome-wide RADseq genotyping. The species is believed to have evolved early in the geological history of the island, and we here examine mating system evolution during colonization and establishment of populations across Madeira. The mating system is highly outcrossing in seven populations and mixed mating in one. Some maternal plants in highly outcrossing populations were inbred, suggesting that mating system varies temporally as well as spatially. This mating system may provide flexibility for establishment of new populations in the dynamic landscapes of oceanic islands while maintaining genetic diversity within populations. Multiple paternity is prevalent in populations, indicating that compatible mates are not limited to a few sires. Our analyses of T. macrorhiza were enabled by several methodological advances included in the v.3 release of the BORICE estimation program. These include SNP filtering programs to generate valid likelihoods and post-processing scripts to partition mating system variation among populations and among maternal plants within populations.
... Pollination services are important in maintaining plant diversity and consequently biodiversity conservation (Bjerknes et al. 2007;Martins 2014). In flowering plants, pollination is a vital process that contributes to production of fruits and seeds (Lázaro et al. 2013;Martins 2014;Barrios et al. 2016;Weissman and Schaefer 2017). It occurs when flower visitors (pollinators) transfer pollen from the male part of a flower (anthers) to the female part (stigmas) of the same or another flower which results into fertilisation (Albano et al. 2009;Flanagan et al. 2009;Lázaro et al. 2013). ...
The exotic invasive plant Parthenium hysterophorus is invading many tropical habitats. While much work has been done on its interactions with other native plants, little is known about its interaction with insect floral visitors and how it impacts pre-existing pollination networks when it invades a site. We carried out surveys on sites with and without P. hysterophorus (invaded and uninvaded, respectively) to investigate its impact on plant–pollinator interactions with two common indicator or target plants (Ocimum gratissimum and Ageratum conyzoides) in Tanzania. During multiple 15 min observation periods in quadrats, the number of arriving flower visitors, duration of visits and visitation rate were measured and compared between sites. Visitation networks of flower visitors were developed by observing flower visitor taxonomic groups and plants visited across both invasion categories. Parthenium hysterophorus was heavily visited by a diversity of flies as taxonomic groups. Indicator plants received fewer flower visitors overall in the invaded site, implying P. hysterophorus may be disrupting pollen flow. Foraging behaviour and flower visitation by Apis mellifera and flies on target plants were particularly negatively affected in the invaded quadrats. Flower visitation rate to target plants was significantly lower in invaded quadrats than in uninvaded quadrats. This study supports work in other parts of the world demonstrating that invasive species can strongly disrupt pollination networks. By attracting flower visitors that could otherwise serve as pollinators of native plant species, P. hysterophorus which is rapidly spreading in eastern African ecosystems could have complex deleterious effects on the wider ecosystem.
... Previous studies showed that generalist species are usually better represented on insect-plant interactions in island ecosystems when compared with the mainland ones [94,95]. For example, the prevalence of generalist pollinators on ecological networks has been reported from several Azorean islands [94,96,97] and similar findings were found for the insect herbivore assemblages associated with several plants across the archipelago [31,32]. These ecological patterns result from the poor dispersal capacity of some groups of insects, which seriously limits their probability of successfully colonizing oceanic islands. ...
Oceanic islands have been providing important insights on the structuring of ecological communities and, under the context of the present biodiversity crisis, they are paramount to assess the effects of biological invasions on community assembly. In this study we compare the taxonomic and functional diversity of insect herbivore assemblages associated with the dominant tree species of Azorean native forests and investigate the ecological processes that may have originated current patterns of plant-herbivore associations. Five dominant trees-Erica azorica, Ilex perado subsp. azorica, Juniperus brevifolia, Laurus azorica and Vaccinium cylindraceum-were sampled in the remnants of the native forest of Terceira Island (Azores) using a standardised methodology. The taxonomic and functional diversity of insect herbivore assemblages was assessed using complementary metrics and beta diversity partitioning analysis (species replacement and richness differences) aiming to evaluate the variation in insect herbivore assemblages within and between the study plant species. Sixty two insect species, mostly bugs (Hemiptera) and caterpillars (Lepidoptera), were found in the five study plants with indigenous (endemic and native non-endemic) insects occurring with higher species richness and abundance than introduced ones. Species replacement was the most important component of insect herbivore taxonomic beta diversity while differences in trait richness played a major role on functional beta diversity. The endemic E. azorica stands out from the other study plants by having associated a very distinct insect herbivore assemblage with a particular set of functional attributes, mainly composed by large bodied and long shaped species that feed by chewing. Despite the progressive biotic homogenization witnessed in the Azores during the last few decades, several strong associations between the endemic trees and their indigenous insect herbivores remain.
... Exotic species often alter ecological processes (Simberloff et al., 2013) and cause severe biodiversity loss. Nevertheless, these species may also provide ecosystem services: exotic arthropods can contribute to important ecological functions in agroecosystems (Rigal et al., 2018) and exotic plants can increase microbial activity (Vilà et al., 2011), introduced natural enemies can control pests (Heimpel and Mills, 2017), or provide ecological "insurance" after the decline of native species (Weissmann and Schaefer, 2017). Understanding the impact of invasive species is particularly important on islands, because of their unique biodiversity and vulnerability (Patiño et al., 2017). ...
... In Euphrasia, large-flowered species are mainly crosspollinated, while small flowered species are mainly self-pollinated (Vitek 1998 ;Yeo 1973) and are pollinated by a mix of introduced and probably native insects belonging mostly to Diptera (Weissmann and Schaefer 2017). Dispersal strategies indicated for both endemic species are hydrochory and semachory (Schaefer 2003). ...
... The latter is a special concern in Corvo island, an UNESCO Biosphere Reserve since 2007, where cattle freely roamed the Caldeirão area at the time sampling for this study was conducted. Eradication of IAS, which compete with native host plant species, will undoubtedly result in a dramatic increase of habitat quality for both Euphrasia species and promote significant future in situ restauration of the populations, since availability of suitable pollinators, and naturally occurring high seed-set and development of young plants in situ has been recently reported (Weissmann and Schaefer 2017). ...
In the Azores Islands, two Euphrasia L. (Orobanchaceae) endemic species are recognized: Euphrasia azorica H.C.Watson, an annual herb, in Flores and Corvo, and Euphrasia grandiflora Hochst. ex Seub., a semi-shrub, in Pico, São Jorge and Terceira. Both species are highly endangered and protected by the Bern Convention and Habitats Directive. A population genetics study was conducted with new microsatellite primer pairs in 159 individuals of E. azorica and E. grandifolia, sampled from populations in Flores, Corvo, Pico and São Jorge. Allele sizing suggested that E. azorica is a diploid while E. grandiflora is a tetraploid. Euphrasia grandiflora revealed higher genetic diversity then E. azorica. The E. grandiflora population of Morro Pelado in São Jorge, displayed higher genetic diversity when compared with all others, while the E. azorica population of Madeira Seca in Corvo, showed the lowest. Private and less common bands were also overall higher in E. grandiflora populations. Population genetic structure analysis confirmed a distinctiveness between the two Azorean endemic Euphrasia, in addition to island-specific genetic patterns in E. azorica. The genetic structure obtained for E. grandiflora was complex with the populations of Cabeço do Mistério in Pico Island and of Pico da Esperança in São Jorge sharing the same genetic group, while a putative spatial barrier to gene flow was still retrieved between both islands. Although some populations of both species might benefit from propagation actions, studies are needed on plant host species and translocations between islands or between some populations of a same island should be avoided, due to the occurrence of putative ESUs. Eradication of invasive species and control of grazing will be fundamental to promote in situ restauration.
A knowledge of bee populations is scarce, particularly in sub-Saharan Africa, where human-induced changes appear to have a considerable negative effect on wild bees. The goal of the study was to assess the abundance, diversity, and richness of bees and their interactions (or visitation) with flowering plants in disturbed and semi-natural habitats in Tanzania. Bees were sampled using sweep nets and pan traps whereas bee-plant interaction and floral abundance were visually assessed. We show that semi-natural habitats are crucial places for bees to forage and nest, as their richness, diversity, and species composition were higher than disturbed habitats. The study areas in semi-natural habitats also had a higher number of bee visits compared to the disturbed habitats. The lower number of bees found in disturbed habitats implies that human-caused alterations have a negative impact on foraging resources and bee communities. Furthermore, we recorded more than 400 bee-plant interactions and high floral abundance in semi-natural habitats compared to disturbed habitats. However, in both disturbed and semi-natural habitats, there was a positive relationship between floral abundance and bee abundance. This reveals that floral resources have a significant impact on bee abundance and their visitation. Our findings demonstrate further that, if natural environments are disturbed and floral resources are depleted, bee populations may decline. Therefore, habitat management, whether disturbed or semi-natural, is critical for the survival of bees.
Citação: Gil A., Picanço A., Moreira M. & Borges P.A.V. (2021) 4.4. Cartografia e análise de serviços de ecossistemas terrestres em pequenas ilhas oceânicas - Casos de estudo relacionados com biodiversidade no Arquipélago dos Açores (Portugal). pp 113-135. In: S.C. Ribeiro, D. Boscolo, G. Ciochetti, A. Firmino, & N. Guiomar, (eds). A Ecologia da Paisagem no Contexto Luso-Brasileiro. Volume II. 1ª Edição. 463p. Editora Appris. Curitiba, Brasil. ISBN: 978-65-250-0280-4.
Aquisição online a partir de https://www.editoraappris.com.br/produto/5166-ecologia-da-paisagem-no-contexto-luso-brasileiro-volume-ii
Genome-wide genotyping and Bayesian inference method (BORICE) were employed to estimate outcrossing rates and paternity in two small plant populations of Tolpis succulenta (Asteraceae) on Graciosa island in the Azores. These two known extant populations of T. succulenta on Graciosa have recently evolved self-compatibility. Despite the expectation that selfing would occur at an appreciable rate (self-incompatible populations of the same species show low but nonzero selfing), high outcross-ing was found in progeny arrays from maternal plants in both populations. This is inconsistent with an immediate transition to high selfing following the breakdown of a genetic incompatibility system. This finding is surprising given the small population sizes and the recent colonization of an island from self-incompatible colonists of T. succulenta from another island in the Azores, and a potential paucity of pollinators, all factors selecting for selfing through reproductive assurance. The self-compatible lineage(s) likely have high inbreeding depression (ID) that effectively halts the evolution of increased selfing, but this remains to be determined. Like their progeny, all maternal plants in both populations are fully outbred, which is consistent with but not proof of high ID. High multiple paternity was found in both populations, which may be due in part to the abundant pollinators observed during the flowering season.
Generalized pollination systems may be favored in early spring flowering plants, as during this period pollinator activity is unpredictable. Many previous studies have concentrated on the importance of diurnal visitors in pollination, and consequently, information on the contribution of nocturnal visitors to pollination in early spring is limited. This study was conducted to evaluate the relative importance of diurnal and nocturnal pollinators in the early spring flowering dioecious shrub Stachyurus praecox (Stachyuraceae), in two temperate forests in central Japan. Visitors to the female and male flowers were observed during day and night, and their relative contributions to seed set were compared. The pollinator observations revealed that the diurnal and nocturnal insects visited both male and female flowers, and that the main flower visitors were diurnal small bees and flies as well as nocturnal settling moths. The diurnal and nocturnal flower visitors also acted as pollinators, as the pollen grains of S. praecox were attached to the insects collected from the female flowers. Pollination experiments demonstrated that the contributions of diurnal pollinators to the seed set were higher than those of the nocturnal pollinators. The results of this study indicate that S. praecox has a generalized pollination system, comprising both diurnal insects and nocturnal settling moths. Although the roles of diurnal insects are more important in the pollination of S. praecox, nocturnal settling moths may have a complementary role in early spring. This study showed that Stachyurus praecox has a generalized pollination system involving both diurnal and nocturnal pollinators. Although diurnal insects are the most important pollinators in S. praecox, nocturnal settling moths may have a complementary role in early spring.
