Ecology and co-existence of two endemic day gecko (Phelsuma) species in Seychelles native palm forest

In island ecosystems, reptiles play diverse ecological roles as a result of niche broadening, which increases potential niche overlap between species. Ecological niche partitioning is a means of reducing direct competition between coexisting species and differences in habitat use among island gecko species have been suggested as a by-product of specialization to feeding on certain resources. Here, we examine modes and drivers of niche partitioning of two endemic species of Phelsuma gecko (Phelsuma sundbergi and Phelsuma astriata) in relict native palm forest in the Seychelles to further understanding of congeneric reptile co-existence in native habitats. Phelsuma abundance, microhabitat use and habitat composition were quantified in different macrohabitat types. P. sundbergi showed a clear preference for habitat dominated by the coco de mer palm, Lodoicea maldivica and a strong association with male individuals of this dioecious species. P. astriata density increased significantly with arboreal biodiversity but did not display a relationship with a specific tree type. High levels of resource segregation were determined along the microhabitat axis, based on differential tree preference. Our results suggest that P. sundbergi and P. astriata may have evolved to co-exist in this habitat type through partitioning of microhabitat as members of a divergent specialist/generalist assemblage determined by consumption of L. maldivica pollen by P. sundbergi. Our findings concur with the hypothesis that differences in habitat use among island reptiles are a by-product of trophic specialization and support the conservation of native habitat for maintenance of reptile diversity

The effect of insect herbivory on the growth and fitness of introduced Verbascum thapsus L.

A majority of the plant species that are introduced into new ranges either do not become established, or become naturalized yet do not attain high densities and are thus considered ecologically and economically unproblematic. The factors that limit these relatively “benign” species are not well studied. The biotic resistance hypothesis predicts that herbivores, pathogens and competition reduce growth and reproduction of individual plants and so suppress population growth of non-native species. We explored the effect of insect herbivory and surrounding vegetation on growth and fitness of the non-native biennial plant Verbascum thapsus (common mullein) in Colorado, USA. Mullein is widespread in its introduced North American range, yet is infrequently considered a management concern because populations are often ephemeral and restricted to disturbed sites. To evaluate the impact of insect herbivores on mullein performance, we reduced herbivory using an insecticide treatment and compared sprayed plants to those exposed to ambient levels of herbivory. Reducing herbivory increased survival from rosette to reproduction by 7%, from 70–77%. Of plants that survived, reducing herbivory increased plant area in the first year and plant height, the length of the reproductive spike, and seed set during the second year. Reducing herbivory also had a marked effect on plant fitness, increasing seed set by 50%, from about 48,000 seeds per plant under ambient herbivory to about 98,000 per plant under reduced herbivory. Our findings also highlight that the relationship between herbivory and performance is complex. Among plants exposed to ambient herbivory, we observed a positive relationship between damage and performance, suggesting that, as predicted by the plant vigor hypothesis, insect herbivores choose the largest plants for feeding when their choice is not restricted by insecticide treatment. In contrast to the strong effects of experimentally reduced herbivory, we found that cover of other plants surrounding our focal plants explained relatively little variation in performance outcomes. Overall, we found that herbivore-induced impacts on individual plant performance and seed set are substantial, and thus may help prevent this naturalized species from becoming dominant in undisturbed recipient communities

Ecological dispersal mechanisms, reproductive ecology, and the importance of scale in Zostera marina in Chesapeake Bay

Previous knowledge of the seed ecology of the clonal seagrass Zostera marina L. (eelgrass) suggests that sexual reproduction is not very important to the population dynamics of eelgrass; however, researchers have hypothesized long-distance dispersal for nearly a century. From a bay-wide sampling effort, viable eelgrass seeds in the seed bank were found throughout most of the lower and middle Chesapeake Bay, but abundance of seeds was highly variable. Lower seed-bank densities were found in middle Chesapeake Bay, the region with slow recovery of eelgrass populations. From natural and artificially created eelgrass populations, regional environmental conditions were found to have a greater impact on reproductive shoot (reproductive effort) and seed (reproductive output) production than small-scale influences of location and patch structure. Detached reproductive shoots of eelgrass (containing viable seeds) held in greenhouse tanks remained buoyant for several weeks before they degraded, sank, and lost all their seeds. In offshore shoal areas, suitable for eelgrass growth and survival, seventy percent of tube caps of the polychaete Diopatra cuprea (found throughout the shallow regions of Chesapeake Bay) had fragmented reproductive shoots built into its walls, suggesting a mechanism for seeding these shallow areas. Viable eelgrass seeds were found throughout the shoreline of south Chesapeake Bay, up to 34 km away from the nearest bed. Additionally, a GIS exercise identified new eelgrass patches up to 108 km from the nearest source population. The use of burlap bags for protecting seeds from predation, burial, or lateral transport maximized germination success over unprotected seeds in the field and provides a new mechanism for restoration efforts. An ecological model of eelgrass reproduction highlighted the potentially significant contribution of seeds to the long-term productivity of eelgrass at different water depths. Exploring theoretical scenarios, the model can be used to predict the total number of seeds produced for one to germinate and successfully establish as a seedling, as well as determine the size of patches, newly created from seeds, based on the number of viable seeds in the seed bank and the vigor of the seedlings that develop

Landscape-scale population dynamics: field observations and modelling of Puya hamata, a flagship plant from the Andes

Important ecological processes happen over long periods of time and at the landscape scale. Effective conservation of biodiversity and management of natural resources and ecosystem services requires an understanding of these processes. Unfortunately, it is often impractical to conduct appropriate long-term, landscape-scale studies. Modelling offers an alternative approach. Complete ecosystems are too complex to model practically, but simulations of simplified systems provide useful insights of practical value. LandBaSE-P is an individual-based model for Puya hamata that provides information about impacts of fire on ecological processes in the páramo of the Reserva Ecológica El Ángel, Ecuador. Puya hamata is a flagship plant affected by fires and plays a key role in a number of ecological processes. This research found Puya hamata germinated much more frequently after fires, can form large aggregations of single recruitment cohorts, suffers very low mortality (with and without fires) once established, and lives up to 28 years. The spatial aggregation of Puya hamata plants reduced effective reproductive output, consistent with the theory that pollinator behaviour around large groups of Puya plants reduces cross-pollination, leading to inbreeding depression and poorer seed viability and germination. Puya hamata’s population structure can be an indicator of recent fire regime. LandBaSE-P simulations showed that population size is not affected by rare, long-distance seed dispersal. However, in the simulations of páramo grasslands, Puya relative germination is maintained in high numbers by burning. Puya hamata has an important role in ecology and biodiversity. The model LandBaSE-P is a complementary tool for conservation and sustainable land management. This thesis shows how fieldwork combined with laboratory studies and modelling, can provide a good understanding of complex dynamics of real-world populations, and generate ideas for management and future research.Consejo Nacional de Ciencia y Tecnología (CONACyT

Molecular phylogenetics, taxonomy and niche-based conservation risk assessment of Thesium L. (Santalaceae)

Thesium L. (Santalales: Santalaceae) is a large (360 species) genus of hemiparasitic perennial or annual species with a mainly Old-World distribution and a greatest concentration in southern Africa (ca. 186 species). Although Thesium is a major component of southern African flora, it often goes unnoticed and is poorly studied. The last revision of the entire genus was done by De Candolle in 1857. South African Thesium was last revised by Hill almost a century ago. Since Hill's revision, the number of collections have grown, and 49 new species have been described. Currently, no comprehensive Thesium taxonomic key exists, and species delimitation remains difficult due to a high variation in character states, rendering the genus in need of major revision. Within southern Africa, ca. 103 species occur in the Greater Cape Floristic Region (GCFR), of which about 72 are regional endemics. The GCFR Thesium, including ecologicalspecialists and generalists, offers an appropriate system for evaluating both the correlates of range extent, specialisation and the relative extinction risks associated with both ecological strategies. Here, it is predicted that a combination of edaphic, elevation and climate variables influence the geographic range of Thesium in the GCFR. Recent phylogenetic hypotheses revealed that Thesium is paraphyletic with respect to Austroamericium, Chrysothesium, Kunkeliella and Thesidium, suggesting the need for generic realignment. In addition, existing subgeneric and sectional classifications of this large genus lack a phylogenetic basis, thus compromising their predictive value. Using an expanded taxon sampling and a combination of nuclear (ITS) and chloroplast (matK, rpl32- trnL and trnL-F) DNA sequence data, chapter two re-assesses the phylogenetic relationships of Thesium and uses these as the basis of a new subgeneric classification of the genus. The phylogeny obtained confirms the need to place the four segregate genera into synonymy, resulting in a monophyletic Thesium. In addition, it resolves five, well-supported major clades within Thesiumwhich I recognize as subgenera. The South African endemic subgenus Hagnothesium is sister to the Eurasian subgenus Thesium (including Thesium, Kunkeliella and Mauritanica). The subgenus Psilothesium, occurring in tropical South America (formerly genus Austroamericium) and tropical Africa, is sister to the rest of the subgenera, which are all confined to South Africa. Within the latter, the subgenus Discothesium consists of subtropical and temperate species, whereas subgenus Frisea, comprising previously recognized sections Annulata, Barbata Frisea, Imberbia and Penicillata, is restricted to the GCFR. To facilitate identification of subgenera, I present identification keys, assigned species, provide brief diagnoses, identified ancestral morphological characters and, supply distribution and ecological data. Thesium subgenus Hagnothesium is endemic to the GCFR. In the past, there has been a propensity in revisionarywork ofthe subgenus Hagnothesium to split taxa into distinctspecies or vice-versa. Consequently, 15 different names exist although only six are accepted formally. Following recent molecular phylogenetic studies, the monophyly of the subgenus Hagnothesium is now well-established, but the circumscription of species within the section remains problematic given the complicated nomenclatural history which has added further confusion. Chapter three presents a revision of subgenus Hagnothesium using a total evidence approach to propose a modern taxonomy. I studied both herbarium collections and plants in their natural populations to circumscribe species boundaries, geographical ranges and estimates of their conservation status. Species of the subgenus Hagnothesium are dioecious, generally having four- merous, campanulate flowers, spikes borne in bract axils and arranged along the length of branchlets, with valvate perianth lobes and a short to absent hypanthial tube. The following eight species were recognized, of which one is here described as new: T. fragile L.f., T. fruticulosum (A.W.Hill) J.C.Manning & F.Forest, T. hirtum (Sond.) Zhigila, Verboom & Muasya comb. nov., T. leptostachyum A.DC., T. longicaule Zhigila, Verboom & Muasya nom. nov., T. microcarpum A.DC., T. minus (A.W.Hill)J.C.Manning & F.Forest and T. quartzicolum Zhigila, Verboom & Muasya sp. nov. I provide updated taxonomic keys, species descriptions, illustrations, distribution maps, new combinations, synonyms, and notes on the red list status for each species. In addition, six new species of Thesium endemic to the GCFR (but not included in subgenus Hagnothesium) are described and illustrated in chapter four. These are: Thesium aspermontanum Zhigila, Verboom & Muasya sp. nov., T. dmmagiae Zhigila, Verboom & Muasya sp. nov., T. neoprostratum Zhigila, Verboom & Muasya sp. nov., T. nigroperianthum Zhigila, Verboom & Muasya sp. nov., T. rhizomatum Zhigila, Verboom & Muasya sp. nov., and T. stirtonii sp. nov. Also, Thesium assimile var. pallidum is elevated to species rank as T. sawae Zhigila, Verboom & Muasya stat. nov. Morphological and ecological differences between species, along with their putative affinities, preliminary conservation status, phenology, etymology and distributional maps are presented. Narrow-ranged species are expected to be more at greater risk of extinction than generalists due to climate change. Such risk is greatest in biodiversity hotspots such as the GCFR, which house both ecological specialists and generalists. It was hypothesized that range size, ecological specialization and consequent climatically-modulated extinction-risk are all phylogenetic structured, such that climate change will precipitate a disproportionate loss of phylogenetic diversity. Past and future species distribution ranges were developed using MaxEnt models based on present-day occurrences and environmental conditions. There was a strong positive correlation between the ecological niche breadth of species, as determined by large-scale environmental variables, and their range extents. One hundred and one Thesium species were modelled, of which 71 species (83%) were predicted to have had broad range sizes during the Last Glacial Maxima, and 27 species (17%) recorded range contractions historically to the present. Similarly, 45 species (44%) will potentially expand their ranges, while 51 species (50%) are predicted to reduce their ranges in the future. Of the 65 species currently ranked as Least Concern or Data Deficient in the South African Red list, 24 species will likely shift into higher extinction risk categories. Interestingly, five ecological specialists (5%), although having experienced a range reduction from the LGM to the present, are predicted to persist in the face of future climate change. However, the range extent, ecological specialisation and extinction risk are phylogenetically random and therefore should have a negligible impact on the phylogenetic diversity of the GCFR Thesium. Overall, this study confirms the monophyly of the genus Thesium and sets its infrageneric classification scheme in place. The context of this classification framework allows the systematic revision of the genus, one clade at a time. Towards this goal, I revised the Hagnothesium clade and additionally described six new species from other clades. The climate, elevation and soil variables influence the distribution range and specialism of GCFR Thesium clades. However, ecological specialism of species and extinction risks were predicted to be phylogenetically random

Tracing coco de mer's reproductive history: Pollen and nutrient limitations reduce fecundity

This is the final version of the article. Available from Wiley Open Access via the DOI in this record.Habitat degradation can reduce or even prevent the reproduction of previously abundant plant species. To develop appropriate management strategies, we need to understand the reasons for reduced recruitment in degraded ecosystems. The dioecious coco de mer palm (Lodoicea maldivica) produces by far the largest seeds of any plant. It is a keystone species in an ancient palm forest that occurs only on two small islands in the Seychelles, yet contemporary rates of seed production are low, especially in fragmented populations. We developed a method to infer the recent reproductive history of female trees from morphological evidence present on their inflorescences. We then applied this method to investigate the effects of habitat disturbance and soil nutrient conditions on flower and fruit production. The 57 female trees in our sample showed a 19.5-fold variation in flower production among individuals over a seven-year period. Only 77.2% of trees bore developing fruits (or had recently shed fruits), with the number per tree ranging from zero to 43. Flower production was positively correlated with concentrations of available soil nitrogen and potassium and did not differ significantly between closed and degraded habitat. Fruiting success was positively correlated with pollen availability, as measured by numbers and distance of neighboring male trees. Fruit set was lower in degraded habitat than in closed forest, while the proportion of abnormal fruits that failed to develop was higher in degraded habitat. Seed size recorded for a large sample of seeds collected by forest wardens varied widely, with fresh weights ranging from 1 to 18 kg. Synthesis: Shortages of both nutrients and pollen appear to limit seed production of Lodoicea in its natural habitat, with these factors affecting different stages of the reproductive process. Flower production varies widely amongst trees, while seed production is especially low in degraded habitat. The size of seeds is also very variable. We discuss the implications of these findings for managing this ecologically and economically important species.Deutsche Forschungsgemeinschaft. Grant Number: KA 3349/2‐1. Eidgenössische Technische Hochschule Zürich. Grant Number: ETH‐37 12‐

Cumulative individual seed production in the polycarpic Caesalpinia gilliesii (Fabaceae): effects of temporal variability in floral display, plant density and pollination

In polycarpic species, floral display size and density of conspecific neighbours are time variable as well as their effects on pollination and fecundity. Here, we address how individual pollinator-dependent seed production responds to changes in floral display size and the density of flowering conspecific neighbours. Using path analysis, we disentangle the partial effects of floral display size, the density of flowering neighbours and pollination intensity on the total seed output of the partially self-compatible shrub Caesalpinia gilliesii during three consecutive reproductive seasons. We also modelled the effects of temporal variability in floral offer and pollination intensity (as the coefficient of variation) on cumulative seed production over the study period. Floral display size had either positive or negative effects on pollination intensity in different reproductive seasons, but conspecific density had no significant effect within each season. However, cumulative seed production increased under lower temporal variability in conspecific density. Our results suggest that, because of the dynamic nature of floral offer in a polycarpic species, the temporal changes in floral display size and density may counteract each other reducing the risk of successive pollination failures and increasing seed production over time.Fil: Calviño, Ana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Ashworth, Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Galetto, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin

Aphandra natalia(Arecaceae) – un recurso poco conocido de piassaba en el oeste de la Amazonía

Aphandra natalia(Balslev & Henderson) Barfod is a multipurpose palm that is exploited both commercially and for subsistence purposes. Its fibers are important in Peruvian and Ecuadorean broom industries and support many people economically. In Brazil, it is found in the western part of Acre, where it is the main source for a local broom market. Data from fieldwork in Peru (2007) suggests that the variation in gross profit per kilogram of fiber is considerable among the different segments in the broom industry. Harvesters and distributors earn negligible amounts of money whereas manufacturers reap of the major part of the earnings. Fiber extraction appears to be sustainable in Ecuador and in some parts of Peru, whereas in other parts of Peru unsustainable harvest occurs, involving felling of entire palm trees for the harvest of fibers. The same destructive extraction method is used in Brazil, where the palm is becoming rare in its natural distribution area.La palmera de piasaba (piassava, piassaba) —Aphandra natalia(Balslev& Henderson) Barfod es una palma que se utiliza para muchos propósitos, tanto comerciales como para la subsistencia de pueblos rurales. Sus fibras son de importancia económica en industrias de escobas en Perú y Ecuador, las cuales sostienen económicamente a muchas personas. En Brasil, esta palma se encuentra en la parte oeste del estado de Acre, donde sus fibras constituyen el recurso principal para el mercado local de escobas. Información de campo originada en Perú en el año 2007, muestra que existe una importante variación en las ganancias económicas por kilo de fibra entre los diferentes sectores de la industria de escobas. Los que cosechan y distribuyen los productos obtienen ganancias muy reducidas, mientras que los productores de escobas son los que más ganan. La extracción de fibras parece ser sostenible en Ecuador y en algunas partes de Perú, mientras que en otras partes de Perú se tumban palmeras enteras para sacar la fibra, lo cual representa un método no sostenible. La misma forma destructiva de cosecha de las fibras existe en Brasil, lo cual ha traído como consecuencia que las poblaciones de la palma se encuentran muy disminuidas en su hábitat natural

My favourite flowering image: a capitulum of Asteraceae

Non peer reviewe

A new pygmy sundew, Drosera Albonotata (droseraceae), from the western wheatbelt and an updated diagnostic key to the orange-flowered pygmy Drosera of Western Australia

A new species of Drosera-Drosera albonotata-from the western Wheatbelt (Western Australia) is described and illustrated. The taxon, which is largely restricted to sandy clay loam soils in Wandoo woodland and shrubland, is morphologically similar to D. miniata and D. coomallo but can be distinguished by its distinct floral features and ecology. A distribution map of the new species and its allies and a revised and updated diagnostic key to the twelve recognised orange-flowered pygmy Drosera in Western Australia are provided