Annual Lifespan Research Articles

Different sets of traits determine transition of alien species along the invasion continuum

Invasive alien species are currently considered as one of the dominant drivers of global environmental change. Till now, the majority of studies have focused on single or a few traits of alien species that facilitate their invasion. Also inclusion of all the traits which determine the transition of aliens along the different stages of invasion continuum (casual, naturalised and invasive) has remained largely overlooked. In this study, we collected a comprehensive trait dataset on 144 alien plant species of Kashmir Himalaya – a global biodiversity hotspot region. To test which traits of alien species, individually or in combination along with anthropogenic factors, determine their transition along the invasion continuum, we employed chi-square tests, boosted regression trees and phylogenetic methods. We found the perennial life span, longer residence time, greater number of introduced regions, and better seed dispersal mechanism were critical in determining the transition from casual to naturalised. The herbaceous growth form, therophyte Raunkiaer life-form, annual life span, achene fruit, longer residence time and broader introduced range were the species' traits determining transition from naturalised to invasive. Aliens introduced as ornamentals have more propensity to become naturalised; whereas aliens introduced unintentionally show overrepresentation at the invasive stage. Phylogeny alone showed mixed results indicating both clustering and dispersion; however, in combination with other traits, it plays a significant role in determining the stage of invasion. Overall, our study disentangles the individual and interactive roles of multiple traits that determine the transition of alien species' along the invasion continuum. Further, we foresee the potential applicability of our findings in designing robust invasion risk analysis protocols and stage-specific invasion management strategies in this Himalayan region, with learnings for elsewhere in the world.

Interactions of Functional Traits With Native Status and Ecosystem Novelty Explain the Establishment of Plant Species Within Urban Ecosystems: Evidence From Berlin, Germany

A key challenge in urban biodiversity conservation is to understand the drivers that govern the population establishment of different groups of species in different urban ecosystems. Here, we ask whether and to what extent vascular plant species establishment (i.e., the ability to establish self-sustaining populations within a certain time span) is driven by interactions of species functional traits, native status, and the type of ecosystem species occur in, with types of ecosystems distinguished by their degree of ecosystem novelty. To answer this question, we use a dataset of 1,178 vascular plant species occurring in Berlin, Germany that originally had been compiled to substantiate the Berlin Red List of endangered plant species. This dataset classifies native and non-native species into casual and established species based on a minimum of 25 years of expert observation. Whether a species is established or casual is distinguished among four broad types of ecosystems: natural remnant, hybrid, novel immature, and novel mature ecosystems. Moreover, we classify species into those native to Berlin and non-native species (split into archaeophytes and neophytes), and link species to selected functional traits and indicator values. By applying ordinal regression within a Bayesian framework, we show that traits are key drivers of these establishment processes and that the traits that drive species establishment differ across types of ecosystems. While across traits, more established species are present in natural remnants, low canopy height, annual life span, and late end of flowering specifically promote establishment in novel immature ecosystems. In hybrid ecosystems, low canopy height and reproduction by seeds are beneficial traits, with the latter promoting establishment in novel mature ecosystems, too. Traits were less important in predicting species establishment in native as compared to non-native species. All types of ecosystems add to urban biodiversity, and trait analyses refine our knowledge on how they can be supported in doing so on the long term. This can help in sharpening conservation measures.

Daily and seasonal population dynamics of Brachynotus sexdentatus (Risso, 1827) (Varunidae: Brachyura: Decapoda) in a temperate coastal lake

The grapsoid Brachynotus sexdentatus (Risso, 1827) is a small sized Mediterranean crab, whose ecology is poorly known despite frequently cited in the scientific literature. High densities occasionally recorded in estuarine habitats suggest this opportunistic species might play a functional role in connecting benthic primary production with consumption at higher trophic levels. The brackish Lake Ganzirri (north-eastern Sicily) hosts a population of this varunid crab, whose differential distribution of juveniles and adults, respectively found on hard and soft substrates, involves different habitat preferences and consequent resource partitioning. Investigation on daily and seasonal dynamics of the soft-bottom dwelling adults showed a male biased population, with size-related differences between sex, station, season and female reproductive phase. Our data, suggesting an annual life span, prolonged spawning and related continuous recruitment, are in agreement with the intrinsic unpredictability of the colonized brackish environment. At last, preliminary in aquaria observations on the characteristic male cheliped vesicles, showed they might involved in agonistic and courtship behaviour.

Floristic diversity and correlates of naturalization of alien flora in urban green spaces of Srinagar city

The sustainable management of green spaces in cities is crucial in achieving the challenging goal of urban sustainability. The common practice of cultivation of alien plants in urban green spaces is often associated with risk of naturalisation (i.e. escape into wild), which can have sometime adverse impacts on biodiversity and ecosystem services. To mitigate these risks, understanding patterns and processes of naturalisation of alien flora in urban green spaces becomes crucial. Here we report the floristic diversity of alien flora and correlates of its naturalisation in the green spaces of Srinagar city – one of the largest urban centres in the Himalaya. We documented 342 plant species belonging to 66 families from the green spaces of Srinagar, predominantly represented by 245 alien species (72%). Among the alien species pool, 133 species (54%) are exclusively under cultivation (non-escapes) and 112 species (46%) grow in the wild (cultivation escapes and accidentally introduced species); and of the latter, 51 were naturalised, 39 casual and 22 invasive. The cultivated alien species escaped into the wild belong to 27 families, and most prominently to the Asteraceae. Habitat-wise, plant dumping sites in the green spaces constituted the most dominant habitat of cultivation escapes. A significant relationship was revealed between the proportion of aliens under cultivation and species traits such as growth form, life span and residence time; and plant species with herbaceous growth form, annual life span and relatively longer residence time showed higher proportion of naturalisation. We found a significant correlation between abundance of the cultivation escapes and residence time (r = 0.507). The present study has generated policy-relevant data on urban green spaces of Srinagar, which can support policy regulations to steer the sustainable development of this rapidly urbanising Himalayan city.

The effects of climate warming and disturbance on the colonization potential of ornamental alien plant species

SummaryA large number of alien plant species have been introduced as ornamental garden plants to Europe, but relatively few have become invasive. Low climatic suitability may be limiting the current invasion potential of many alien ornamental species. However, with ongoing disturbance and climate change, this barrier may be reduced for some species.Here, we tested how colonization ability (a prerequisite for invasion) of frequently planted alien ornamentals depends on disturbance and heating, and on their species characteristics. We sowed seeds of 37 non‐naturalized alien herbaceous garden‐plant species into native grassland plots with and without disturbance, and with and without infrared‐heating lamps. To assess whether their responses differ from those within the regional wild flora, we also sowed 14 native species and 12 naturalized alien species. During 2 years, we assessed the likelihoods of germination, first‐year survival, second‐year survival and flowering of these 63 study species.The heating treatment, which also reduced soil moisture, decreased all measures of colonization success, but more so for sown native species than for the non‐naturalized and naturalized alien ones. The disturbance treatment increased colonization success, and because heating decreased productivity of the undisturbed grassland plots, it also increased invasibility of these plots. Average colonization success of non‐naturalized aliens was reduced by heating, but some species were not affected or performed even better with heating, particularly those with an annual life span and a high seed mass. Winter hardiness improved colonization ability of non‐naturalized aliens, but this advantage was reduced in the heated plots.Synthesis. Disturbance increased and heating decreased the absolute colonization success of most of the 63 species sown. However, heating had stronger adverse effects on the resident grassland and sown native species than either type of sown alien species. Together, these results suggest that some alien plants may have greater colonization success relative to native plants under a warmer climate.

Biotic homogenization in an increasingly urbanized temperate grassland ecosystem

AbstractQuestionHow does urbanization and associated declines in fire frequency alter the floristic composition of native temperate grasslands? Does it lead to: (1) biotic homogenization, i.e. compositional similarity between remnants increases; (2) biotic differentiation, whereby similarity between remnants declines, or; (3) clustered differentiation, where similarity between remnants remains unchanged, but composition shifts from the historical state?LocationVictoria, Australia.MethodsUsing site‐level surveys, we examined changes in the floristic similarity of 29 urban grasslands from 1992 to 2013 and compared these changes to those of 63 rural grasslands from 1989 to 2014. Community‐level changes in the representation of key functional traits were also examined in urban grasslands, with traits advantaged following disturbance regime change and urban fragmentation predicted to increase in frequency.ResultsOur results supported the biotic homogenization hypothesis in urban grasslands. Compositional similarity between grasslands increased principally because of an increase in commonly shared non‐native species, with change in native composition comparatively minor. However, no evidence of biotic homogenization was found in rural grasslands, with no significant change in overall composition identified. The most urbanized sites had the highest number of non‐native species in both the current and historical data sets, yet non‐native composition over the past two decades changed the most in sites on the urban fringe, becoming more similar to sites closer to the urban core. As expected, following declines in fire frequency and increased urbanization, the overall composition of urban grasslands shifted to taller plant species, while native species capable of vegetative reproduction and exotic species with an annual life span increased in frequency.ConclusionUrbanization was an important driver of biodiversity change in the investigated system, with increasing competition intensity in response to disturbance regime change a likely cause of biotic homogenization. Our results demonstrate that non‐native species are a key driver of biotic homogenization, emphasizing the importance of managing non‐native immigration and maintaining historical disturbance processes once native ecosystems become urbanized.

Phylogeny of the tribe Fumarieae (Papaveraceae s.l.) based on chloroplast and nuclear DNA sequences: Evolutionary and biogeographic implications

Little research has been done at the molecular level on the tribe Fumarieae (Papaveraceae). Papaveraceae is a model plant group for studying evolutionary patterns despite the lack of a reference phylogeny for this tribe. We investigated the phylogenetic relationships within the tribe to complete the molecular data for this family in order to help understand its character evolution and biogeographic pattern. We used maximum-parsimony and Bayesian approaches to analyze five DNA regions for 25 species representing 10 of the 11 Fumarieae genera and five outgroups. Evolutionary pathways of four characters (habit, life span, type of fruit, and number of seeds per fruit) were inferred on the phylogeny using parsimony. The ancestral distribution areas were reconstructed using dispersal-vicariance analysis. Fumarieae is monophyletic and includes three groups that agree with the morphology-based subtribes: Discocapninae, Fumariinae, and Sarcocapninae. Within subtribes, the relationships among genera were different from those obtained with morphological data. Annual life span, nonchasmophytic habit, and a several-seeded capsule were the basal character states for the tribe. The ancestor occupied a continuous area between West Eurasia and Africa. Vicariances explain the divergence between lineages Discocapninae (South Africa) and Fumariinae-Sarcocapninae (Mediterranean), and the disjunction of Fumariinae (Mediterranean-Central Asia). Molecular phylogeny confirms the subtribal classification of Fumarieae based on morphology. However it provides different results regarding the relationships among genera within each subtribe, which affects the inference of the evolutionary pathway followed by the four selected characters. The disjunct distribution of the tribe is explained by different vicariance scenarios.

Evolution of Pollen/Ovule Ratios and Breeding System in Erodium (Geraniaceae)

Abstract Most perennial species of Erodium have medium to high pollen/ovule (P/O) ratios and are dichogamous mixed-mating species endemic to the mountain ranges of the Mediterranean. In contrast, the annual species of this genus, which are often adapted to disturbed sites, are adichogamous selfers with low P/O ratios and wide distributions. According to the present reconstruction of the evolution of Erodium, recurrent perennial to annual shifts occurred from a time earlier than the establishment of the Mediterranean climate during the Pleistocene. The diversification of the terminal clades containing annuals and perennials is dated to 6.4–2 Mya, between the onset of the Messinian (Miocene) and the end of the Pliocene. By adapting to several types of breeding systems (mixed-mating and selfing), many species of Erodium were able to meet the challenges of climatic deterioration and the changes in pollinators that took place at the end of the Tertiary. High selfing and an annual lifespan seem to have evolved ...

Differences in trait compositions between rocky natural and artificial habitats

Question: What are the differences in trait compositions that enable native plants to colonise comparable natural and man-made habitats? Are these traits independent of phylogenetic relationships between species? Location: Czech Republic. Methods: The relative importance of biological, ecological and distributional traits of native species was studied, using a dataset of 75 species growing in rock and wall habitats in the Czech Republic. Species preferences for individual habitats due to climatic conditions and proportions of different vegetation types in their surroundings were partialled out using partial canonical correspondence analysis. The pattern of plant traits along a gradient from natural rock habitats to secondary wall habitats was analysed using regression trees and generalized linear models with and without phylogenetic correction. Results: The most common native species colonising rock habitats are phanerophytes, mostly woody juveniles, with a CSR life strategy and most are adapted to epizoochory. Summer green leaves, annual life span, CR life strategy, reproduction mostly by seeds and dispersal by ants are all traits positively associated with the ability of species to colonise wall habitats. These species are also characterised by their high demand for nutrients, temperature, base-rich substrates and light. Biological and ecological traits are more important for colonising new habitats than traits related to species dispersal ability or phylogenetic relationships between species. Biological and ecological traits alone explained 29.3% of variability in the species dataset, while dispersal characteristics and phylogeny alone explained 9.1% and 4.8%, respectively. Conclusions: We outline how the process of environmental filtering determines native species assemblages and identify a set of species traits that enable them to persist in particular habitats. We conclude that although urbanisation generally results in loss of natural habitats, there are new, man-made habitats potentially suitable for native species.

A new annual species of Bellium (Asteraceae) from the Balearic Islands

A new species, Bellium artrutxensis (Asteraceae: Astereae), is described from the therophytic pastures of southern Minorca (Balearic Islands). The analysis of nuclear ribosomal internal transcribed spacer (ITS) sequences showed that the new taxon was closely related to Bellium bellidioides , but differed with regard to the annual lifespan, the absence of epigeal stolons, and the presence of a patent eglandular indumentum on the leaves. The new taxon shows morphological features that are well suited for the colonization of dry environments with a marked summer drought, and may be of adaptive significance. The new species is diploid (2 n = 18) and shows up to two accessory chromosomes in root tissues. B chromosomes have not been reported previously in other species of Bellium .© 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 65-77.

A temporal investigation of grazer dynamics, nutrients, seagrass leaf productivity, and epiphyte standing stock

An investigation of seagrass-epiphyte controlling factors was conducted within aThalassia testudinum meadow in Florida Bay from March 2000 to April 2001. Univariate and multivariate analyses were performed using water column nutrient concentrations, temperature, salinity, and turbidity, and gastropod grazer abundances, seagrass leaf area index, and leaf turnover rate data to explain the variation in total epiphyte standing stock, epiphyte chlorophylla, and epiphyte autotrophic index. Turbidity was positively correlated with total epiphyte standing stock and accounted for the most variation. Observations of adhered sediment onT. testudinum leaves and the combination, of increased total epiphyte standing stocks and low autotrophic indices observed in February and April 2001 suggest that the settling of resuspended sediments following turbidity events is one of the temporal mechanisms for increased epiphyte accumulation. Total epiphyte standing stock was also negatively correlated with the abundance of a robust gastropod grazer community dominated byTurbo castanea, Tegula fasciata, andModulus modulus. Distinct temporal size cohorts ofT. castanea andT. fasciata throughout the study period suggest recruitment in spring and an annual lifespan. Nutrient concentrations can also account for some of the temporal variation in total epiphyte standing stock, epiphyte chlorophylla, and autotrophic index. The low variation ofT. testudinum leaf turnover rates was unable to account for any of the variation in the epiphyte parameters.

EXTENDED MATERNAL CARE OBSERVED IN PARALLORCHESTES OCHOTENSIS (AMPHIPODA, GAMMARIDEA, TALITROIDEA, HYALIDAE)

Abstract Several peracarid crustaceans have been shown to engage in extended maternal care for their growing offspring after the juveniles hatch from the brood pouch of the female. In this study, we describe the maternal care of the epibenthic gammaridan Parallorchestes ochotensis Brandt and examine its ecological implications. The juveniles stayed in the female's expanded brood pouch for at least seven weeks after hatching. The duration of extended maternal care of P. ochotensis was comparatively longer and the growth of P. ochotensis juveniles slower than reported for other epibenthic peracarids. The juveniles molted at least twice whilst in maternal care. This species probably has an annual life span, and they reproduce only once a year. In P. ochotensis, maternal care was shown to constrain juvenile growth in the experimental predator-free conditions, contrary to other epibenthic peracarids. Most epibenthic peracarid species with extended maternal care are suspension feeders, but P. ochotensis is an h...

Extended Maternal Care Observed in Parallorchestes Ochotensis (Amphipoda, Gammaridea, Talitroidea, Hyalidae)

Several peracarid crustaceans have been shown to engage in extended maternal care for their growing offspring after the juveniles hatch from the brood pouch of the female. In this study, we describe the maternal care of the epibenthic gammaridan Parallorchestes ochotensis Brandt and examine its ecological implications. The juveniles stayed in the female’s expanded brood pouch for at least seven weeks after hatching. The duration of extended maternal care of P. ochotensis was comparatively longer and the growth of P. ochotensis juveniles slower than reported for other epibenthic peracarids. The juveniles molted at least twice whilst in maternal care. This species probably has an annual life span, and they reproduce only once a year. In P. ochotensis, maternal care was shown to constrain juvenile growth in the experimental predator-free conditions, contrary to other epibenthic peracarids. Most epibenthic peracarid species with extended maternal care are suspension feeders, but P. ochotensis is an herbivore so probably maternal care of this species limits juvenile feeding opportunities and results in a decrease of juvenile growth. However, where normal predation exists, maternal protection contributes significantly to juvenile survival. In P. ochotensis, to enhance relatively low fecundity in conditions where predation pressure is high, extended maternal care for relatively long periods is necessary to protect offspring even if it constrains juvenile growth.

LATERAL PLATE VARIATION IN GALICIAN STICKLEBACK POPULATIONS IN THE RIVERS MIÑO AND LIMIA, NW SPAIN

AbstractWe examined lateral plate variation in populations of stickleback, Gasterosteus aculeatus, from the rivers Miño and Limia in Galicia (Northwest Spain), by analysing morphs, number of lateral plates, and position of the plates. In order to test for sexual dimorphism, the means and variances of plates were compared in males and females of some populations. No significant differences were found between sexes, therefore all remaining populations were analysed without controlling for sex. As stickleback populations in Galicia have an annual life span, the populations from the river Miño were divided in two age groups to compare lateral plate number. Analysis of each group revealed significant differences among populations, in accordance with the large amount of variation found in populations from other regions. Analysis of samples collected from the same place and at the same time of year, but in different years, indicated that there was little year to year variation. This suggests that populations are well adapted to their habitat, or that environmental conditions did not change significantly during the period of sampling. Finally, we propose a new method for the evaluation of scute variation analysis of the position of lateral plates. Cluster analysis of our data clearly differentiated populations from the rivers Miño and Limia.