Island Plant Research Articles

Characterization of endophytic and symbiotic bacteria within plants of the endemic association Centaureetum horridae Mol

We investigated the internal association of bacteria with Astragalus terraccianoi and Centaurea horrida, two endemic plants of the Mediterranean islands, forming the phytosociological association Centaureetum horridae, typical of windswept cliffs on the rocky shores of Asinara (Sardinia, Italy) and other limited locations. Sampling occurred in the protected natural park of the Asinara island. Roots and stems of the two plants and the root nodules of A. terraccianoi were surface sterilized in order to remove external and rhizospheric microbiota and to subsequently isolate the culturable bacterial communities. Plate counts revealed densities of endophytes between 3.7 × 102 and 2.8 × 104 colony forming units per gram of fresh weight. 16S rDNA sequencing revealed the occurrence of bacteria displaying high similarity with Actinobacterium sp., Paenibacillus sp., Rhizobium sp., Methylobacterium sp., Pedobacter panaciterrae, Aerococcus viridans, Stenotrophomonas rhizophila, Bacillus sporothermodurans, Bacillus pumilus, Bacillus simplex, Bacillus flexus, Streptomyces ciscaucasicus and Dyella sp. The putative nitrogen-fixing rhizobium symbiont of A. terraccianoi was identified for the first time. It turned out to belong to the slow-growing Bradyrhizobium genus and to share a 97% similarity with Bradyrhizobium canariense. It was found to be nonculturable and to coexist in nodules with a number of different endophytes.

Understanding the relative roles of disturbance and species interactions in shaping Mississippi River island plant communities

In order to better understand the factors governing community assembly on riverine islands, we conducted a greenhouse experiment that examined the effects of species interactions in combination with flooding that mimicked hydrologic gradients found on Mississippi River islands. Specifically, we examined the effects of inter and intra-specific competition and three disturbance treatments (drained, drought, and flood) on the growth performance of three island-ubiquitous herbaceous plant species (Amaranthus palmeri, Cyperus strigosus. and Xanthium strumarium). We predicted a decrease in interspecific competitive effects in disturbance treatments. Specifically, we expected A palmeri to be most affected by flooding treatment based on its facultative upland status suggesting that it should be a poor tolerator of flooded conditions. X. strumarium and C. strigosus both facultative wetland species in their status, should tolerate flooding, but we predict that C. strigosus should have greater stress tolerance due to its perennial life history. Because we find these species coexisting at the same elevation zones on riverine islands, we also predicted stronger intraspecific competition effects. Our results indicate that disturbance indeed affected competitive interactions, but the effects were species-specific. X. strumarium showed stronger competitive effects when grown with conspecifics while C. strigosus experienced greater competition with heterospecifics under drought treatments. Based on its wetland indicator status and life history characteristics, we expected A palmeri to exhibit a facilitative effect, as it is typically an upland species, but instead it was impacted most by interspecific competition. Our study indicates that factors other than competition, facilitation, and flood tolerance (e.g., priority effects) may be controlling island plant community dynamics, further studies are required.

Comparison of the Essential Oils of Leaves and Stem Bark from Two Different Populations of Drimys Winteri a Chilean Herbal Medicine

The chemical composition of the essential oils obtained by hydrodistillation of stem bark and leaves of Drimys winteri J.R. et G. Foster var. chilensis /DC A. Gray (Winteraceae) from Chiloe Island (ID) and Continental Chile (Santiago) (CD) were studied by GC and GC/MS. Sesquiterpene hydrocarbons constituted the main chemical groups in the stem bark oils, with alpha-santalene, trans-beta-bergamotene and curcumenes as the major components. Monoterpenes constituted the main chemical groups in the leaves of Island plants with alpha-pinene (23.1%) beta-pinene (43.6%) and linalool (10.5%) as the main components whereas sesquiterpenes (germacrene D 17.6%) and phenylpropanoids (safrole 20.8%) are the most abundant in the leaves of Continental plants.

High genetic diversity and significant population structure in Cedrus brevifolia Henry, a narrow endemic Mediterranean tree from Cyprus

Endemic island plant species with a narrow distribution are often, but not always, linked to low genetic variation within populations and a lack of differentiation among populations. Cedrus brevifolia is a narrow endemic island tree species of Cyprus. Its range is restricted to a single forest, divided into five neighbouring sites. This study, using biparentally inherited nuclear microsatellites and paternally inherited plastid (chloroplast) microsatellites, assessed the genetic variation of C. brevifolia within its sole population and the level of genetic differentiation among formed sites. The results from both markers showed high diversity (nuclear H T = 0.70; plastid H T = 0.93), strongly suggesting that the species did not experience severe bottleneck events or extensive genetic drift. Besides, the maintenance of a high genetic diversity in C. brevifolia may suggest that it originates from a widespread congener species. Significant genetic differentiation at nuclear (G ST = 0.052) and plastid (G ST = 0.119) markers was found among the formed sites. Remarkably, the relatively high genetic differentiation found at plastid markers was comparable to values observed in two widespread congener cedar species. The genetic differentiation probably occurred due to fragmentation of a previously uniform population. This would lead to the shaping of different genetic groups (Bayesian analysis) and to significant population substructure. Furthermore, significant values observed for both isolation by distance and large-scale spatial genetic structure could indicate ineffective gene flow among sites and the early geographical isolation of the more isolated sites from the core population.

Mapping unexplored genomes II: genetic architecture of species differences in the woody Sonchus alliance (Asteraceae) in the Macaronesian Islands

Despite numerous, well-documented evolutionary histories of plant groups which underwent rapid radiation in various oceanic archipelagos, very little is known about the genetic basis of species differences and adaptive radiation. This paper represents the first such study in the Macaronesian Islands using non-model endemic plants, the woody Sonchus alliance. Here I inferred the genetic basis of species differences between two Canary Island endemics, the herbaceous perennial, shade tolerant Lactucosonchus webbii and the woody, coastal desert perennial Sonchus radicatus by quantitative trait locus (QTL) mapping using AFLP markers. A total of 23 QTL (7.3-23.8% PVE; phenotypic variance explained) for 11 morphological traits were found, one for flowering time (31% PVE), and five QTL (7-10.7% PVE) for two physiological traits (intrinsic water use efficiency and stomatal conductance). Interpreted cautiously, these results suggest that major morphological and some physiological differences between the two species are controlled by numerous genes with small to moderate effect. This implies that major morphological changes in island plants can be more complex than suggested by other studies, such as in Tetramolopium in the Hawaiian Islands. The genetic basis of arborescence on islands, one of the most spectacular convergent features of plants across different lineages and archipelagos, is also discussed.

Effects of Double‐Crested Cormorants (Phalacrocorax auritus Less.) on Island Vegetation, Seedbank, and Soil Chemistry: Evaluating Island Restoration Potential

The unique plant community on Middle Island, Lake Erie, Canada, has been greatly modified by double‐crested cormorants (Phalacrocorax auritus Less.) whose population has increased enormously in the last two decades. The aims of this study were to assess the impact of cormorants on island tree canopy, understorey vegetation, soil seedbank, and soil chemistry. The ultimate objective was to assess the resilience of the vegetation community for recovery should cormorant nest densities decrease significantly. Forty‐three point stations were established in a grid system covering the entire island. The herbaceous and woody vegetation was surveyed over 2 years and tree crown damage was assessed at each point station. In 2008, soil samples were collected for both chemical analysis and a seedbank inventory. Vegetation and seedbank species richness were impoverished compared to the vegetation surveyed prior to cormorant colonization. Cormorants affected not only the tree canopy where they nested but also the understorey vegetation. Exotic plant species were very common in the standing vegetation and constituted the bulk of the abundance in the seedbank. However, there was little relationship between aboveground vegetation and seedbank composition. Cormorants appeared to have little influence on seedbank richness, abundance, and composition. Notably, several species of conservation interest were found in the aboveground vegetation and in the seedbank providing a positive sign for future efforts to restore island plant communities.

Cosmeceutical effect from native medicinal plants of blue belt Ulleung islands

ABSTRACT Objectives：The purpose of this research was total polyphenol contents, ant i-oxidant activities, anti-inflammatory activities and anti-wrinkle activities of Ulleung islands plants for application as a cosmeceutical ingredientsMethods：We were experimented total polyphenol contents, anti-oxidant ac tivities, anti-inflammatory activity and anti-wrinkle activities.Results：In the physiological activities, most Ulleung islands plants is showed the highest anti-oxidant, anti-inflammatory activity in ABTS+ radical cation scavenging a ctivity, hydrogen peroxide(H 2 O 2 ) scavenging activity, nitric oxide scavenging activity. All experiment of t he water and ethanol extract from the Ulleung islands plants ingredients were gradually increased as well. Conclusions：These results suggest that extracts from Ulleung islands plants can be used in natural ingredient in food or cosmetic industry.Key words：anti-oxidant, anti-inflammatory, anti-wrinkle, plants of blue b elt Ulleung, Aruncus dioicus var. kamtschaticus Hara, Athyrium acutipinnulum, Solidago virga-aurea var. Gigaatea

Nitrogen content and respiration rate in leaves of the Wrangel Island plants

Protein and total nitrogen contents and respiration rate (at 10°C) were estimated in 22 herbaceous species of Wrangel Island (lat. 71° N). Protein nitrogen content and respiration rate in leaves of these plants were found to exceed 1.3- and 2.4-fold the corresponding indices in the temperate zone plants at the same temperature. The relationship between the content of protein nitrogen and respiration in the Wrangel Island species was insignificant (r2 = 0.137), and the authors conclude that the protein content in the northern plants is not the factor determining the respiration rate in particular plant species. It follows that rather than depend on such indirect indices as nitrogen content, the models for carbon cycle in the North should employ direct respiration measurements at natural plant habitats.

The tolerance of island plant–pollinator networks to alien plants

Summary1.Invasive alien plant species pose a severe threat to native plant communities world‐wide, especially on islands. While many studies focus on the direct impact of alien plants on native systems, indirect effects of plant invaders on co‐flowering natives, for example through competition for pollination services, are less well studied and the results are variable.2.We used six temporally and taxonomically highly resolved plant–pollinator networks from the island of Mahé, Seychelles, to investigate the indirect impact of invasive alien plant species on remnant native plant communities mediated by shared pollinators. We employed fully quantitative network parameters and information on plant reproductive success, and pollinator diversity and behaviour, to detect changes in plant–pollinator networks along an invasion gradient.3.The number of visits to and fruit set of native plants did not change with invasion intensity. Weighted plant linkage and interaction evenness, however, was lower at invaded sites than at less invaded sites. These patterns were primarily driven by shifts in interactions of the most common pollinator, the introduced honey beeApis mellifera, while weak interactions and strong native interactions remained unchanged.4.Synthesis.The implications of these findings are twofold: first, quantitative network parameters are important tools for detecting underlying biological patterns. Secondly, alien plants and pollinators may play a greater role in shaping network structure at high than low levels of invasion. We could not show, however, whether the presence of invasive plants result in a simplification of plant–pollinator networks that is detrimental to native plants and pollinators alike.

Options for sustainable sewage sludge management in small wastewater treatment plants on islands: The case of Crete

This work examines four essentially different and widely established methods for the treatment of sewage sludge and determines the applicability of each one of them in the economical, geographical and environmental settings of the island of Crete in Greece. Under these conditions, the combination of lime stabilization and solar drying appears to be the optimum solution for sewage sludge management. For each of the treatment technologies considered, cost indicator spreadsheets were developed that enabled the automatic calculation of the total cost. Τhe cost of the lime stabilization–soar drying combined treatment is comparable to the cost of composting or thermal drying alone. The judgment criteria and the economical parameters used for the evaluation of the methods may be a useful tool for other wastewater treatment plants in various Mediterranean islands.

Darwin’s Galapagos gourd: providing new insights 175 years after his visit

AbstractThe year 2010 marks the 175th anniversary of Charles Darwin’s visit to the Galapagos Islands. A recent paper by J. C. Briggs, ‘Darwin’s biogeography’ (Journal of Biogeography, 2009, 36, 1011–1017), summarizes Darwin’s contributions to the field of biogeography, stressing the importance of his natural history specimens. Here, we illustrate how a plant collected by Darwin during his visit to Floreana and not collected since can provide insights into dispersal to oceanic islands as well as extinction of island plants, based on ancient DNA from Darwin’s herbarium specimen.

Are island plant communities more invaded than their mainland counterparts?

Questions: Are island vegetation communities moreinvaded than their mainland counterparts? Is thispattern consistent among community types?Location: The coastal provinces of Catalonia andthepara-oceanicBalearicIslands,bothinNESpain.These islands were connected to the continent morethan 5.35 million years ago and are now locatedo200km from the coast.Methods: We compiled a database of almost 3000phytosociological releve´s from the Balearic Islandsand Catalonia and compared the level of invasionby alien plants in island versus mainland commu-nities. Twenty distinct plant community typeswere compared between island and mainland coun-terparts.Results: The percentage of plots with alien species,number, percentage and cover percentage of alienspecies per plot was greater in Catalonia than in theBalearic Islands in most communities. Overall,across communities, more alien species were foundin the mainland (53) compared to the islands (onlynine). Despite these differences, patterns of the levelof invasion in communities were highly consistentbetween the islands and mainland. The most in-vaded communities were ruderal and riparian.Main conclusion: Our results indicate that para-oceanic island communities such as the BalearicIslands are less invaded than their mainlandcounterparts. This difference reflects a smaller re-gional alien species pool in the Balearic Islands thanin the adjacent mainland, probably due to differ-ences in landscape heterogeneity and propagulepressure.Keywords: alien plants; Balearic Islands; communitysimilarity; Mediterranean communities; para-ocea-nic islands; releve´; species richness.Nomenclature: Bolo`s & Vigo (1984–2001), Rivas-Martinez et al. (2001).

Associations of leaf miners and leaf gallers with island plants of different residency histories

AbstractAim Introduced plant species are less likely to be attacked by herbivores than are native plant species. Isolated oceanic islands provide an excellent model system for comparing the associations between herbivore species and plant species of different residency histories, namely endemic, indigenous (non‐endemic) or introduced (naturalized or cultivated) species. My aim was to test the prediction that, on isolated oceanic islands, introduced plant species have a lower tendency to have an association with insect herbivores than do endemic and indigenous plant species.Location Ogasawara (Bonin) Islands in the western Pacific Ocean.Methods I examined the presence/absence of leaf‐mining and leaf‐galling insect species on 71 endemic, 31 indigenous, 18 naturalized and 31 cultivated (introduced but not naturalized) species of woody plants from 2004 to 2008.Results Leaf‐mining insect species were found on 53.5%, 35.5%, 11.1% and 16.1% and leaf‐galling species were found on 14.1%, 9.7%, 5.6% and 0% of endemic, indigenous, naturalized and cultivated plant species, respectively. Species of Lepidoptera (moths) and Hemiptera (primarily psyllids) comprised the dominant types of leaf miners and leaf gallers, respectively.Main conclusions The incidence of leaf miners and leaf gallers differed as a function of residency history of the plant species. Introduced (naturalized and cultivated) species were less frequently associated with leaf miners and leaf gallers than were native (endemic and indigenous) species, indicating that the leaf‐mining and leaf‐galling insect species, most of which feed on leaves of a particular native plant genus (i.e. they show oligophagy), have not yet begun to utilize most introduced plant species.

Screening of elastase and tyrosinase inhibitory activity from Jeju Island plants

To identify new active cosmetics ingredients of natural origin, we screened 299 parts of 263 plant species collected from Jeju Island, the southernmost island of the Korean Peninsula. Plant parts were investigated for their elastase and tyrosinase inhibitory activity for the purpose of identifying anti-aging and skin-whitening ingredients with the potential for use as raw materials in cosmetics. In the anti-elastase inhibition assay, 3 extracts, including Aesculus turbinata, Taxillus yadoriki, and Cornus walteri, showed high inhibitory activity (inhibition concentration ( I C ) 5 0<50 /vg/mL). The I C 5 0 of A. turbinata and T. yadoriki was 43.1 /vg/mL and 36.4 /vg/mL, respectively; C. walteri showed the highest elastase inhibition activity ( I C 5 0 = 26.1 /vg/mL). In the tyrosinase inhibition assay, 4 extracts, including C. walteri(139.2 vg/mL), Maackia fauriei (149.3 /vg/mL), Toxicodendron succedaneum (142.3 /vg/mL), and Sophora flavescens (41.6 v g/mL), showed significantly greater tyrosinase inhibition activity than the positive controls Distylium racemosum (145.9 /vg/mL) and arbutin (180.3 /vg/mL). However, they showed lower activity compared to the positive controls Morus alba (11.9 vg/mL) and Morus bombycis (22 v g/mL). These results suggest that medicinal plants possessing several biological activities may be potent inhibitors of the processes involved in pigmentation increases and aging. Further investigations will focus on in vivo assays and the chemical identification of the major active components responsible for anti-aging and whitening.

Conservation and restoration of plant–animal mutualisms on oceanic islands

Islands harbour much of the world’s threatened biodiversity. Recent work has highlighted how it is not species diversity per se but rather the interactions between organisms that breathes life into ecosystems. Thus, the real challenge to preserving and restoring biodiversity on islands is not to only focus on species themselves, but more importantly on maintaining and restoring the integrity of interactions between the species. Here we argue that mutualistic plant–animal interactions play a pivotal role with regards to conservation and restoration on islands. Furthermore, these interactions are ideally suited for inter-island comparisons due to ecological and evolutionary similarities across geographical and taxonomical boundaries. The similarities include highly generalised mutualistic systems, the evolution and readjustment of plant reproductive traits, and a disharmony in taxonomic groups of mutualists, compared to continental ecosystems. We highlight past and present threats to island plant–animal mutualisms, as well as the challenges and opportunities inherent to these interactions. In particular, we (1) argue that mutualistic networks provide an ideal approach to collect information and advance our knowledge on the systems, (2) suggest the use of interactions as biodiversity monitoring and assessment tools, (3) highlight the differences and similarities between pollination and seed dispersal interactions in the context of restoration, and (4) briefly discuss the ambiguous role of alien invasive species in the management of mutualistic interactions. Finally, we highlight how a recently proposed but controversial restoration strategy, rewilding, can be gainfully applied to and further advanced in island settings. & 2009 R ¨

Genetics, Evolution, and Conservation of Island Plants

Islands are ideal model systems for testing ecological and evolutionary theory. This article reviews and synthesizes the findings of 24 studies of population genetics of island plants to gain insight into ecological and evolutionary processes on these unique, insular habitats. The studies reviewed found evidence for limited gene flow among islands and high genetic structure, but few tested for isolation by distance or among models of gene flow. Few studies compared diversity on islands with mainland populations or tested for bottlenecks, and the small number that did produced split results. Studies of rare species generally found that multiple islands would need to be protected to preserve genetic diversity. This review shows that surprisingly little work has been done to test theory using studies of population genetics on islands, and further work on testing among models of gene flow and examining population bottlenecks would be especially useful.

Pollination biology of Harrisia portoricensis (Cactaceae), an endangered Caribbean species

Traits associated with self-pollination are common features of island plant communities. In this work, we studied the pollination biology and the breeding system of Harrisia portoricensis, an island columnar cactus, to test for the presence of inbreeding and inbreeding depression. For H. portoricensis, which bears flowers with typical outcrossing morphology, the results from 322 h of direct observations and videotaping showed that visits to flowers by animals were uncommon. Controlled pollinations demonstrated that H. portoricensis has a partially self-compatible breeding system that it is not autogamous and thus requires an external mechanism for the movement of pollen to set fruit. We detected differences in seed size, seed mass, germination success, and multiplicative fitness estimates between self- and cross-pollination treatments. We found that progeny resulting from natural and self-pollination treatments showed signs of inbreeding depression compared with progeny resulting from cross-pollination; however, the magnitude of the inbreeding depression was less than 50%. Our combined results suggest that for this species an endogamous breeding system should be favored by natural selection.

Botrychium ascendens W. H. Wagner (Ophioglossaceae) in Newfoundland and Notes on its Origin

Abstract Botrychium ascendens is reported from Fogo Island in Newfoundland as an addition to the flora of the province. Fogo Island plants are identical to plants in western North America, including those from the type locality, in comparisons of leaf morphology, spore size, and allozyme expression. Comparisons are made with related and confusing taxa, B. campestre, B. crenulatum, B. lineare, and the American genotype of B. lunaria. Newfoundland plants display a high level of fixed heterozygosity and large spore size, indicating they are allotetraploid, and supporting suggestions that B. ascendens is derived from ancient hybridization between B. crenulatum and the B. lineare/campestre complex. The current distribution of Botrychium ascendens and its putative parents suggest it probably originated in western North America and migrated across northern Canada to Newfoundland.

Darwin on island plants

Islands played a key role in Charles Darwin's observations and experiments on plant dispersal. By means of these experiments, he expunged the old idea that a given species could originate at multiple times and in multiple places. More importantly, by seeing the capabilities for dispersal of plant seeds, fruits and branches, he was able to develop ideas of how plants reach islands and thus he is one of the founders of plant biogeography. For facts regarding floristic distribution of plants, Darwin relied on other workers, most notably Sir Joseph Dalton Hooker. Among his insights were the differences between oceanic and continental islands on a floristic basis, ideas on how age of island and distance from mainland areas influenced composition of island floras, the nature of endemism on islands and the role islands and archipelagos served as stepping stones in dispersal. Ingenious at proposing hypotheses, but always respectful of facts, Darwin sought explanations for plant adaptations on islands at a time when knowledge of island botany was little more than floristic in nature. These explanations are compared with selected recent works in island botany.

Climate alters response of an endemic island plant to removal of invasive herbivores

Islands experience higher rates of species extinction than mainland ecosystems, with biological invasions among the leading causes; they also serve as important model systems for testing ideas in basic and applied ecology. Invasive removal programs on islands are conservation efforts that can also be viewed as powerful manipulative experiments, but few data are available to evaluate their effects. We collected demographic and herbivore damage data for Castilleja mollis Pennell, an endangered plant endemic to Santa Rosa Island, California, over a 12-year period before, during, and after the implementation of control for introduced cattle, deer, and elk. We used these long-term data to explore mechanisms underlying herbivore effects, assess the results of herbivore reduction at the scales of both individual plants and populations, and determine how temporal variability in herbivory and plant demography influenced responses to herbivore removals. For individual plants, herbivore effects mediated by disturbance were greater than those of grazing. Deer and elk scraping of the ground substantially increased plant mortality and dormancy and reduced flowering and growth. Stem damage from browsing did not affect survivorship but significantly reduced plant growth and flower production. Herbivore control successfully lowered damage rates, which declined steeply between 1997 and 2000 and have remained relatively low. Castilleja mollis abundances rose sharply after 1997, suggesting a positive effect of herbivore control, but then began to decline steadily again after 2003. The recent decline appears to be driven by higher mean growing season temperatures; interestingly, not only reductions in scraping damage but a period of cooler conditions were significant in explaining increases in C. mollis populations between 1997 and 2002. Our results demonstrate strong effects of introduced herbivores on both plant demography and population dynamics and show that climate-driven variation may counteract and mask positive responses to herbivore removal. Regional mean temperatures already have risen significantly over the last 50 years, suggesting that climate change could increasingly swamp the effects of management targeted at other environmental problems. Similar interactions between climate and invasive species will play an even greater role in future management, with long-term data sets like this critical to quantifying such effects.