Establishment Of New Species Research Articles

The effects of Bacillus subtilis on the immunity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounder (Paralichthys olivaceus) with two feeding methods: Continuous versus discontinuous feeding

Probiotics as dietary additives can improve weight gain, feed efficiency, and disease resistance in cultured fish. In this research, we evaluated and compared the effects of Bacillus subtilis on immunity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounder (Paralichthys olivaceus) by a 30-day feeding experiment based on a continuous feeding schedule (E1) and a discontinuous feeding schedule (E2). As a result, the use of B. subtilis exerted the best positive effects on survival rate, enzyme activity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounders. Alkaline phosphatase (AKP), lysozyme (LZM), and superoxide dismutase (SOD) activities in the liver of E2 were higher than those of E1 (P < 0.05). Furthermore, the villi length in the intestinal tract and the fold length in the stomach of E2 were also higher than in E1 (P < 0.05). The il-1 expression levels in the spleen were significantly increased in E2 (P < 0.05) compared to E1. We performed 16 S rRNA sequencing analysis to find that Bacillus in E1 (1.06%) and E2 (1.01%) had higher relative abundances than in E0 (0.053%) at the end of the experiments, indicating that short-term application of B. subtilis with the continuous or discontinuous feeding method can allow both the adaptation of the ecosystem to the presence of probiotics by the establishment of new species in the gut microbiota and the ability these new probiotic species to perform corresponding functions. No significant differences in the ability of probiotic establishment were observed between E1 and E2. Our findings provided a unique perspective to explore the mechanism of immune enhancement with probiotics and to screen the optimal administration strategy in aquaculture application for probiotic use. Together, these results point to some level of enhancement in immune status by continuous and discontinuous feeding after a short-term feeding period, which could be used as a prophylactic strategy for flounder health management.

Rickettsial pathogens drive microbiota assembly in Hyalomma marginatum and Rhipicephalus bursa ticks.

Most tick-borne pathogens (TBPs) are secondarily acquired by ticks during feeding on infected hosts, which imposes 'priority effect' constraints, as arrival order influences the establishment of new species in a microbial community. Here we tested whether once acquired, TBPs contribute to bacterial microbiota functioning by increasing community stability. For this, we used Hyalomma marginatum and Rhipicephalus bursa ticks collected from cattle in different locations of Corsica and combined 16S rRNA amplicon sequencing and co-occurrence network analysis, with high-throughput pathogen detection, and in silico removal of nodes to test for impact of rickettsial pathogens on network properties. Despite its low centrality, Rickettsia showed preferential connections in the networks, notably with a keystone taxon in H. marginatum, suggesting facilitation of Rickettsia colonisation by the keystone taxon. In addition, conserved patterns of community assembly in both tick species were affected by Rickettsia removal, suggesting that privileged connections of Rickettsia in the networks make this taxon a driver of community assembly. However, Rickettsia removal had minor impact on the conserved 'core bacterial microbiota' of H. marginatum and R. bursa. Interestingly, networks of the two tick species with Rickettsia have similar node centrality distribution, a property that is lost after Rickettsia removal, suggesting that this taxon drives specific hierarchical interactions between bacterial microbes in the microbiota. The study indicates that tick-borne Rickettsia play a significant role in the tick bacterial microbiota, despite their low centrality. These bacteria are influential and contribute to the conservation of the 'core bacterial microbiota' while also promoting community stability.

New Middle Ordovician (Darriwilian) faunas from the Sultanate of Oman

New trilobite material and the first graptolites from outcrop are described from the Am5 member of the Amdeh Formation near Al Fleij in northeast Oman. The sediments in which these faunas occur are interpreted as distal-shelf deposits with storm beds packed with brachiopods and orthoconic nautiloids. The deposits and its faunas are considered of late Darriwilian age and younger than the shallower-water Am5 deposits known from other outcrops. No palynomorphs could be recovered to confirm this due to the increased burial temperature the Al Fleij area has experienced.The trilobites are of considerable palaeo-biogeographic interest as few faunas of this age are known from the Arabian Plate, though their preservation precludes the establishment of new species. They include Isabelinia aff. glabrata, Liomegalaspides sp., Neseuretus tristani, Neseuretinus sp. and the deeper-water forms, Cyclopyge cf. C. bohemica, Arthrorhachis sp. and Brachypleura sp. The graptolites are pendent Didymograptus spp. of later Darriwilian type.Rare elements of the conodonts Nordiora, Amorphognathus and Microzarkodina have been recovered from shell beds that occur interbedded with the faunas. They too indicate a late Darriwilian age and differ from richer, restricted, shallow-water faunas known from the Am5 at other locations, and the more cosmopolitan shelf fauna from the Ayim Member of the Rann Formation of the United Arab Emirates.A coarser, 80 m-thick, terrestrial sequence containing igneous pebbles, included in the Am5 in the 1980s, is shown from the occurrence of fossil plants to be of Permian age and probably equivalent to the Basal Saiq Clastics of Jabal al Akhdar.

Taxonomic and functional macrofaunal diversity along a gradient of sewage contamination: A three-year study

We investigated the structural and functional changes of the soft-bottom macrofaunal community following the improvement of a wastewater treatment-WWT plant. The macrofauna was collected at increasing distance from the main outfall in 2018, 2019, and 2021. Organic matter and nutrients were analysed in the water column near the outfalls to detect possible changes due to the improved treatment. We examined Functional Entities-FEs (i.e. a unique combination of species functional traits), species richness, Shannon-Wiener diversity-H′, and taxonomic and functional β-diversity. From 2018 (before the year of the treatment change), to 2021, we noted a gradual decrease of organic carbon in the water column. In contrast, sediment characteristics (i.e. grain-size) did not change before and after treatment enhancement, with the exception of redox potential. Species richness and FEs gradually increased moving far from the source of organic contamination and after wastewater treatment enhancement, especially near the outfall. We observed different phases of macrofaunal succession stage after the WWT amelioration. A ‘normal stage’, i.e. slightly lower species richness, was reflected in decreasing functional richness. Higher taxonomic β-diversity values with significant turnover components indicated that the community was subjected to broad changes in species composition. However, functional β-diversity did not follow the same pattern. After treatment improvement, modified environmental conditions led to the establishment of new species, but with the same functions. Towards 2021, the community improved its resilience by increasing functional redundancy and reduction of vulnerability, which enhanced community stability. The latter was also reflected in the well-balanced proportion of macrofaunal feeding habits after the WWT upgrade. Integrating the classical taxonomic approach with the analysis of FEs, and environmental characteristics can provide an accurate insight into macrofauna sensitivity to stressors that are likely to lead to changes in the ecological state of an area.

Responses of oribatid mites to warming in boreal peatlands depend on fen type

Climate warming is expected to disproportionately affect high latitude and alpine systems such as boreal peatlands. Previous studies observing changes in both plant and microbial communities suggest boreal peatlands may shift from carbon sinks to sources under warming. But few studies have investigated oribatid mites (Acari: Oribatida) under climate change scenarios in peatland systems, despite oribatid mites being well represented in terms of diversity in boreal peatlands. We performed a large-scale experimental field manipulation of warming in two contrasting peatland sites in Northern Ontario, Canada, and sampled oribatid mites over four years following three years of passive warming and one full growing season of active warming. We found that warming had contrasting effects on the oribatid mite community at both peatland sites, and depended on the peatland type. Specifically, we observed an increase in species richness at the drier, Sphagnum-dominated site and a reduction in species richness at the wetter, Carex-dominated site. That said, we suggest that these outcomes arise from the same mechanism, namely warming-induced reductions in soil moisture that impacted semi-aquatic species and facilitated the establishment of new species, likely from surrounding forests. We also observed increases in small-bodied species suggesting direct metabolic effects from warming. As such, we show that peatland oribatid mite community composition is driven to an extent by interactions between temperature and moisture but dependant on peatland type. As oribatid mite communities are responsive to multiple environmental changes, and play important mid-trophic level roles in soil food webs, changes in oribatid mite community composition may have consequences for carbon flux in peatland systems.

Priority effects in microbiome assembly.

Advances in next-generation sequencing have enabled the widespread measurement of microbiome composition across systems and over the course of microbiome assembly. Despite substantial progress in understanding the deterministic drivers of community composition, the role of historical contingency remains poorly understood. The establishment of new species in a community can depend on the order and/or timing of their arrival, a phenomenon known as a priority effect. Here, we review the mechanisms of priority effects and evidence for their importance in microbial communities inhabiting a range of environments, including the mammalian gut, the plant phyllosphere and rhizosphere, soil, freshwaters and oceans. We describe approaches for the direct testing and prediction of priority effects in complex microbial communities and illustrate these with re-analysis of publicly available plant and animal microbiome datasets. Finally, we discuss the shared principles that emerge across study systems, focusing on eco-evolutionary dynamics and the importance of scale. Overall, we argue that predicting when and how current community state impacts the success of newly arriving microbial taxa is crucial for the management of microbiomes to sustain ecological function and host health. We conclude by discussing outstanding conceptual and practical challenges that are faced when measuring priority effects in microbiomes.

What matters for vegetation regeneration in Brazilian subtropical grasslands: seeders or resprouters?

Fire is an important ecological and evolutionary factor affecting plant communities worldwide. After fire, plants can resprout or germinate and systems may differ according to their post-fire regeneration strategies. Therefore, the main aim of this study was to analyze the most important regeneration strategies in Brazilian subtropical grasslands. Moreover, we point out differences in seedlings and resprouts between burned and mowed plots, in order to detect differences in community response to different types of disturbance. We analyzed seven pairs of plots (burned and mowed) in two sites with different fire histories: FB – frequently burned grasslands, and E – exclusion of fire for six years. After treatments, vegetation was described and seedlings and resprouts were sampled. Plants were later grouped in species groups for statistical analyses. Less than 20% of established plants came from seedlings and only three species were obligate seeders. Most species resprouted after treatments. Number of seedlings and resprouts did not show significant differences between treatments in each site. However, a higher number of species with seedlings was observed in site FB. More new species with seedlings established in burned than mowed plots in site FB. Seedlings of forbs recruited more in burned than in mowed plots. Resprouter was the most important strategy for all studied species groups, particularly for graminoids. Our results show the importance of vegetative regeneration in the studied subtropical grasslands, independently of disturbance, and the importance of fire for the establishment of new species, maintaining thus, plant diversity.

Acrogenospora (Acrogenosporaceae, Minutisphaerales) Appears to Be a Very Diverse Genus.

During a study of diversity and taxonomy of lignicolous freshwater fungi in China, nine species of Acrogenospora were collected. Seven of these were new species and they are described and illustrated. With morphology, additional evidence to support establishment of new species is provided by phylogeny derived from DNA sequence analyses of a combined LSU, SSU, TEF1α, and RPB2 sequence dataset. Acrogenospora subprolata and A. verrucispora were re-collected and sequenced for the first time. The genus Acrogenospora is far more species rich than originally thought, with nine species found in a small area of Yunnan Province, China.

Predators drive community reorganization during experimental range shifts.

Increased global temperatures caused by climate change are causing species to shift their ranges and colonize new sites, creating novel assemblages that have historically not interacted. Species interactions play a central role in the response of ecosystems to climate change, but the role of trophic interactions in facilitating or preventing range expansions is largely unknown. The goal of our study was to understand how predators influence the ability of range-shifting prey to successfully establish in newly available habitat following climate warming. We hypothesized that fish predation facilitates the establishment of colonizing zooplankton populations, because fish preferentially consume larger species that would otherwise competitively exclude smaller-bodied colonists. We conducted a mesocosm experiment with zooplankton communities and their fish predators from lakes of the Sierra Nevada Mountains in California, USA. We tested the effect of fish predation on the establishment and persistence of a zooplankton community when introduced in the presence of higher- and lower-elevation communities at two experimental temperatures in field mesocosms. We found that predators reduce the abundance of larger-bodied residents from the alpine and facilitate the establishment of new lower-elevation species. In addition, fish predation and warming independently reduced the average body size of zooplankton by up to 30%. This reduction in body size offset the direct effect of warming-induced increases in population growth rates, leading to no net change in zooplankton biomass or trophic cascade strength. We found support for a shift to smaller species with climate change through two mechanisms: (a) the direct effects of warming on developmental rates and (b) size-selective predation that altered the identity of species' that could colonize new higher elevation habitat. Our results suggest that predators can amplify the rate of range shifts by consuming larger-bodied residents and facilitating the establishment of new species. However, the effects of climate warming were dampened by reducing the average body size of community members, leading to no net change in ecosystem function, despite higher growth rates. This work suggests that trophic interactions play a role in the reorganization of regional communities under climate warming.

Intercepted Mosquitoes at New Zealand's Ports of Entry, 2001 to 2018: Current Status and Future Concerns.

Mosquito vectors are extending their range via international travel and trade. Climate change makes New Zealand an increasingly suitable environment for less tropically adapted exotic mosquito vectors to become established. This shift will add a multiplier effect to existing risks of both the establishment of new species and of resident exotic species extending into new areas. We describe trends in the border interceptions of exotic mosquitoes and evaluate the role of imported goods as a pathway for these introductions. Ae. aegypti and Ae. albopictus, the two most commonly intercepted species, were only intercepted in Auckland. Used tyres and machinery were the main mode of entry for both species. The majority of Ae. albopictus were transported as larvae by sea, while most Ae. aegypti were transported as adults by air. Continuing introductions of these mosquitoes, mainly arriving via Japan or Australia, increase the risk of the local transmission of mosquito-borne diseases in New Zealand in general and in the Auckland region in particular. These findings reinforce the need for a high performing and adequately resourced national biosecurity system, particularly port surveillance and inspection. Recommended biosecurity improvements are described.

Revisiting the infectivity and pathogenicity of Cryptosporidium avium provides new information on parasitic sites within the host

BackgroundCryptosporidium spp. are protozoans that cause diarrheal illness in humans and animals, including birds, worldwide. The present study was aimed to revisit the infectivity and pathogenicity of C. avium, recently considered to be a valid avian-infecting species of Cryptosporidium, and foster further understanding of its biological characteristics.ResultsResults showed that no Cryptosporidium oocysts were detected in the feces of experimentally inoculated BALB/c mice, Mongolian gerbils, quail or budgerigars within 30 days post-infection (dpi). Oocysts were first detected in feces of 3-day-old and 40-day-old hens at 8 and 9 dpi, respectively. In ducks infected with C. avium, oocysts were first detected at 9 dpi. Oocysts of infected animals were studied using a nested-polymerase chain reaction (PCR) technique for the SSU rRNA gene, actin gene, HSP70 gene and Cryptosporidium oocyst wall protein gene (COWP) detection. Restriction fragment length polymorphism (RFLP), using SspI and VspI restriction enzymes, was carried out to genotype the species and obtained amplification products were sequenced. Cryptosporidium developmental stages were found in the longitudinal plica of the bursa fabricii (BF) of hens, with high levels observed in histological sections and scanning electron microscopy. No pathological changes were observed.ConclusionsThese findings indicate that the bursa fabricii may be the primary site of C. avium infection. More biological data are needed to support the establishment of new species and contribute to the taxonomy of Cryptosporidium.

Structural and functional responses of plant communities to climate change-mediated alterations in the hydrology of riparian areas in temperate Europe.

The hydrology of riparian areas changes rapidly these years because of climate change‐mediated alterations in precipitation patterns. In this study, we used a large‐scale in situ experimental approach to explore effects of drought and flooding on plant taxonomic diversity and functional trait composition in riparian areas in temperate Europe. We found significant effects of flooding and drought in all study areas, the effects being most pronounced under flooded conditions. In near‐stream areas, taxonomic diversity initially declined in response to both drought and flooding (although not significantly so in all years) and remained stable under drought conditions, whereas the decline continued under flooded conditions. For most traits, we found clear indications that the functional diversity also declined under flooded conditions, particularly in near‐stream areas, indicating that fewer strategies succeeded under flooded conditions. Consistent changes in community mean trait values were also identified, but fewer than expected. This can have several, not mutually exclusive, explanations. First, different adaptive strategies may coexist in a community. Second, intraspecific variability was not considered for any of the traits. For example, many species can elongate shoots and petioles that enable them to survive shallow, prolonged flooding but such abilities will not be captured when applying mean trait values. Third, we only followed the communities for 3 years. Flooding excludes species intolerant of the altered hydrology, whereas the establishment of new species relies on time‐dependent processes, for instance the dispersal and establishment of species within the areas. We expect that altered precipitation patterns will have profound consequences for riparian vegetation in temperate Europe. Riparian areas will experience loss of taxonomic and functional diversity and, over time, possibly also alterations in community trait responses that may have cascading effects on ecosystem functioning.

Dry-weight energy density of prey fishes from nearshore waters of the upper Niagara River and Buffalo Harbor, New York

Energy density of prey fishes can affect the survival, growth, and fitness of piscivorous fishes, and these vital rates may change – for better or worse – after fish communities are altered by the establishment of new species. Invasive round goby (Neogobius melanostomus) and rudd (Scardinius erythrophthalmus) are highly abundant in the upper Niagara River and Buffalo Harbor and serve as alternative food for piscivores. However, there is a paucity of information on the energy density of native and invasive prey fishes in these waters. To better understand the energy density of available prey fishes in nearshore areas of the upper Niagara River and Buffalo Harbor, we compared the energy densities of: (1) native fishes and invasive fishes, (2) age-0 and yearling-and-older conspecific fishes, and (3) upper Niagara River and Buffalo Harbor conspecific fishes. Fishes were collected from New York waters of the upper Niagara River and Buffalo Harbor during early August through mid-September 2013. We combusted fishes in a bomb calorimeter to determine dry-weight energy densities (J/g) for two invasive and eight native species. Energy densities were dependent on an interaction between fish species and age group, and did not differ between the upper Niagara River and Buffalo Harbor. Yearling-and-older spottail shiner (Notropis hudsonius) had a significantly higher energy density than all other species examined and was the only species with a significant difference in energy density between age classes. Rudd had an energy density similar to most native fishes; and, although not significantly lower, round goby energy density was lower than most native fishes. Our energy density estimates can be used to better understand mechanisms affecting growth and condition of piscivorous fishes in the upper Niagara River and Buffalo Harbor.

Depletion of heterogeneous source species pools predicts future invasion rates

Summary Predicting how increasing rates of global trade will result in new establishments of potentially damaging invasive species is a question of critical importance to the development of national and international policies aimed at minimizing future invasions. Centuries of historical movement and establishment of invading species may have depleted the supply of species available for future invasions, and it has been suggested that the problem of invasions will diminish as a result of this. However, the extent to which source pool depletion affects future invasions remains unclear. Here we describe a mechanistic model that captures the simultaneous effects of depletion of source species pools along with increases in pathway rates (e.g. imports) to predict future numbers of new invasions. We assume that the distribution of species abundance within invasion pathways is positively skewed, which is modelled using a log‐normal distribution. Given their high propagule pressure, the most abundant species are likely to invade first, while the many rare species are likely to invade only under high pathway volumes. We apply this model to the case study of bark beetle, Scolytinae, invasions in the USA. Source species pools in Europe and Asia (225 and 655 species of Scolytinae, respectively) are much larger than numbers that have historically established (16 and 32). Parameterization of the model indicates a highly skewed species abundance distribution in the pathway and this is confirmed by species frequencies in port inspection records, thus explaining why only a small fraction of species has historically invaded. Forecasts from the model indicate that with increasing rates of imports, more species from these regions are likely to invade in the future despite the depletion of the most abundant species from source species pools. Previous statistical models tend to underestimate future establishments in the presence of increasing import rates due to their failure to account for key underlying mechanisms. Policy implications. The mechanistic model developed here is widely applicable for predicting future invasions of all taxa and provides insights into how increases in rates of imports counteract the species pool depletion effect, resulting in the continued establishment of new species.

Heteroploid reticulate evolution and taxonomic status of an endemic species with bicentric geographical distribution.

Reticulate evolution is considered to be among the main mechanisms of plant evolution, often leading to the establishment of new species. However, complex evolutionary scenarios result in a challenging definition of evolutionary and taxonomic units. In the present study, we aimed to examine the evolutionary origin and revise the species status of Campanula baumgartenii, a rare endemic species from the polyploid complex Campanula section Heterophylla. Morphometry, flow cytometric ploidy estimation, AFLPs, as well as chloroplast and nuclear DNA sequence markers were used to assess the morphological and genetic differentiation among C. baumgartenii, C. rotundifolia and other closely related taxa. Tetra- and hexaploid C. baumgartenii is morphologically and molecularly (AFLP) differentiated from sympatric C. rotundifolia. Contrasting signals from nuclear (ITS) and chloroplast (trnL-rpl32) markers suggest a hybrid origin of C. baumgartenii with C. rotundifolia and a taxon related to the alpine C. scheuchzeri as ancestors. Additionally, hexaploid C. baumgartenii currently hybridizes with co-occurring tetraploid C. rotundifolia resulting in pentaploid hybrids, for which C. baumgartenii serves as both seed and pollen donor. Based on the molecular and morphological differentiation, we propose to keep C. baumgartenii as a separate species. This study exemplifies that detailed population genetic studies can provide a solid basis for taxonomic delimitation within Campanula section Heterophylla as well as for sound identification of conservation targets.

A generalization of the taxon cycle

A generalization of the taxon cycle

Restoring phylogenetic diversity through facilitation

Phylogenetic diversity enhances ecosystem functioning but restoration ecology has not taken advantage of this knowledge. We propose plant facilitation as a mechanism to promote phylogenetic diversity in restoration practices. We planted three functionally different species (Gypsophila struthium, Sedum album, and Limonium sucronicum) in a degraded gypsum ecosystem in Spain and found that after 7 years, the species with nurse traits (G. struthium) survived longer and facilitated the establishment of new species forming phylogenetically diverse neighborhoods. These facilitation‐driven phylodiverse communities may potentially produce a cascade of benefits on ecosystem functioning.

Recovery dynamics and invasibility of herbaceous plant communities after exposure to experimental climate extremes

Do climatic extremes increase the invasibility of plant communities, for example through the creation of gaps and the associated local surplus of available resources? To address this question, small experimental communities consisting of three forb species were first subjected to extreme drought and/or heat treatments in different seasons and species mortality and end-of-season biomass were examined. Then, the establishment of new species and their effects on the productivity of the community were recorded in two subsequent years without additional treatments.The immediate response to the experimentally induced extremes was similar in all three originally planted species, with drought treatments in summer and autumn, especially when combined with heat, inducing the greatest plant mortality. Recovery in terms of end-of-season aboveground biomass was species-specific however. The dominant species, the N-fixer Trifolium repens, recovered poorly from the drought and drought+heat treatments. Differences in community biomass between treatments and to the controls were no longer significant in the next year. Graminoid species, especially, successfully invaded the communities, possibly because of functional dissimilarity with the species already present. Invasibility in the year following the extreme events was increased in communities that had been exposed to both a heat wave and a drought, but the number of newly established species did not increase community productivity. The identities of invading species varied distinctly, but had no clear relation with the extreme events the communities had been exposed too.The induced climate extremes greatly affected the survival and productivity of the species and influenced the invasibility of the plant communities. However, none of the community properties seemed to be affected in the longer run, as the induced responses faded out after one or two years.

Climatic Facilitation of the Colonization of an Estuary by Acartia tonsa

Global change has become a major driving force of both terrestrial and marine systems. Located at the interface between these two realms, estuarine ecosystems are probably the place where both direct and indirect effects of human activities conspire together to affect biodiversity from phytoplankton to top predators. Among European estuarine systems, the Gironde is the largest estuary of Western Europe and many studies have provided evidence that it has been affected by a variety of anthropogenic stressors such as thermal and chemical pollution, physical alterations and exploitation, especially for maritime traffic. In such a context, species introduction is also a current major issue with the establishment of strong competitive species that could lead to ecosystem reorganization with potential decrease or even disappearance of native species. In the Gironde estuary, this hypothesis was proposed for the invasive shrimp species Palaemon macrodactylus as a decrease in the native species abundance was observed at the same time. Although species introduction often takes place via ballast water, the influence of climate-driven changes on the establishment of new species remains a key issue. The calanoid copepod Acartia tonsa, observed in the Gironde estuary for the first time in 1983, have since colonized most part of the estuary, reaching a level of abundance comparable to the dominant native species Eurytemora affinis. In this study, using both the concept of the ecological niche sensu Hutchinson (fundamental and realized niches) and statistical models, we reveal that the dynamics of the colonization of A. tonsa was facilitated by environmental conditions that have become closer to its environmental optimum with respect to temperature and salinity.

Lost and found: Short-term dynamics of the flora on 100 small islands in the White Sea

The aim was to uncover factors that influence short-term (decade) flora dynamics and species richness of northern marine islets characterized by poor flora and weak anthropogenic pressure. The study used presence–absence data of vascular plant species on 100 small uprising islets of the Kandalaksha Gulf of White Sea (Northern Karelia, Russia). We investigated the influence of islands' attributes on species richness and rates of flora dynamics. Two island types were analyzed separately: younger, stone-like and older, islet-like (which generally are larger and have higher diversity of habitats). Sampled islands were studied via classical biogeographical per island approach and metapopulation per species approach. Stone-like islands had noticeably poorer flora with higher rates of immigration and extinction when compared to those of islet-like islands. The species number for islet-like islands correlated positively with number of habitats, abundance of different habitat types and island area. Species richness of stone-like islands correlated positively only with number of habitat types. Plant species associated with birds, crowberry thickets and coastal rocks were the most stable, and the species of disturbed habitats were significantly less stable. Floristic changes that have occurred have been caused by the massive establishment of new species rather than the extinction of pre-existing taxa. Thus, most of these islands are still in the colonization (assortative) stage. While we found no relationship between island area and species number for stone-like islands, this relationship was seen on islet-like islands.