Similar Life History Characteristics Research Articles

Species-Level Recognition and Redescription of the Kentucky Arrow Darter, Etheostoma spilotum Gilbert (Percidae: litocara)

The Kentucky Arrow Darter, Etheostoma spilotum, endemic to the upper Kentucky River basin of eastern Kentucky, is redescribed and recognized as a distinct species closely related to E. sagitta in the upper Cumberland River basin and E. nianguae in the Osage River drainage (Missouri River basin). Originally described as a subspecies of E. nianguae, it was later considered a full species and then a subspecies of E. sagitta, based on close geographic proximity to Cumberland basin populations and overlapping meristic variation interpreted as character intergradation. We present meristic, morphometric, and genetic data that support species-level recognition of E. spilotum. It differs from E. sagitta by lower counts of total and pored lateral scales, lower counts of caudal peduncle scales, fewer second dorsal-fin rays, and fewer pectoral-fin rays. Interspecific divergence of E. spilotum and E. sagitta is further demonstrated through analyses of variation in the mitochondrial nd2 gene and species delimitation using genome-wide double digest restriction-site associated DNA sequencing. Although allopatrically distributed, both species inhabit upland headwater streams on the Cumberland Plateau and have similar life history characteristics. Endemism, fragmented distributions, and low densities and genetic diversity within populations make these species extremely vulnerable to anthropogenic activities. Etheostoma spilotum was federally listed as threatened in 2016 due to degradation of stream habitat and water quality in the upper Kentucky basin that has eliminated the species from a significant portion of its range.

Limited conservation efficacy of large-scale marine protected areas for Pacific skipjack and bigeye tunas

Large-scale, no-take marine protected areas (MPAs) have been established in several locations in the Pacific and expansion of such areas to reach 30% of the ocean area is actively promoted in some quarters. Justification for the establishment of large oceanic MPAs often includes the conservation benefits that they would bring for tuna stocks, which are the subject of important commercial fisheries in the Pacific. The aim of this paper was to evaluate the conservation efficacy of an existing MPA, the Phoenix Islands Protected Area (PIPA) and a series of large hypothetical MPAs each constituting approximately 33% of the western and central Pacific Ocean, for two important and contrasting tuna species, skipjack and bigeye tuna. The evaluation was conducted by comparing control and counterfactual simulations in which the estimated population and fishery dynamics of the species were modelled using a high-resolution modelling framework known as SEAPODYM (Spatial Ecosystem And Population DYnamics Model). We found that stock-wide conservation benefits of the PIPA for these species, assuming that total fishing effort is maintained, to be weak to non-existent, and only modest increases in spawning biomass of both species occur within and in the near vicinity of the PIPA itself. For the larger 33% hypothetical MPAs, changes in stock-wide spawning biomass were estimated to be -0.1% to +5.8% for skipjack tuna and +4.8% to +12.0% for bigeye tuna. Conservation efficacy of MPAs for species such as tropical tunas is limited by their wide larval dispersal and high mobility of later life stages, which spatially dissipate the protective effects of MPAs. Also, the displacement of fishing effort from MPAs to areas remaining open can have negative consequences for stocks and fisheries performance in those areas. We conclude that large oceanic MPAs are not likely to be effective frontline management tools for tropical tunas and other species having similar life history characteristics.

Long-term spatiotemporal variation in density of a tropical folivore: responses to a complex disturbance regime.

The Anthropocene is a time of unprecedented and accelerating rates of environmental change that includes press (e.g., climate change) and pulse disturbances (e.g., cyclonic storms, land use change) that interact to affect spatiotemporal dynamics in the density, distribution, and biodiversity of organisms. We leverage three decades of spatially explicit data on the density of a tropical folivore (Lamponius portoricensis [Insecta, Phasmida]) in a hurricane-mediated ecosystem (montane rainforest of Puerto Rico), along with associated environmental attributes, to disentangle the effects of interacting disturbances at multiple spatial scales. Spatiotemporal variation in density at a small spatial scale is affected by disturbance-related characteristics (hurricane severity, time after most recent major hurricane, ambient temperature, and understory temperature), legacies of previous land use, and understory habitat structure. Nonetheless, only a small proportion of spatiotemporal variation in density was related to those characteristics. In contrast, the majority of interannual variation in mean density at a larger scale was related to disturbance characteristics and understory habitat structure. These factors combine to affect a weak and declining trend in the density of L. portoricensis over time. The low resistance of L. portoricensis to Hurricane Hugo, as compared to Hurricanes Georges and Maria, likely arose because a drought followed Hurricane Hugo. The disturbance regime of the region is predicted to include increases in ambient temperatures, frequency of high-intensity storms, and frequency of droughts. Such trends may combine to threaten the conservation status of L. portoricensis, and other species with which it shares similar life history characteristics.

Genetic diversity in high-mountain Thymus species in Bulgaria revealed by ISSR genetic markers

High mountain populations of the plant species possess particular interest from both evolutionary and conservation points of view. The mode of distribution, limited gene flow and severe environmental conditions act as evolutionary forces shaping the level and distribution of genetic diversity within and among populations. The paper reports results of a study on four populations of Thymus praecox aggr., including the taxa T. vandasii and T. jankae. Two populations are located in Rila Mts (Belmeken dam and Yastrebets), one – in Pirin (Vihren hut) and one – in the Rhodopes (Perelik hut). Eleven inter simple sequence repeat (ISSR) markers were applied to document the genetic diversity within and among populations. The level and distribution of the diversity correspond to the values reported in other studies on the species of the genus Thymus and other species with similar life-history characteristics. The populations from Rila and Pirin were genetically closer to each other, while the population from the Rhodopes was the most differentiated. The results are discussed in the light of the conservation and sustainable use of the species resources.

Genetic homogeneity detectable in the sedentary moray eel Gymnothorax minor based on mitochondrial DNA analysis

On the basis of traditional morphological classification, Gymnothorax minor has been misidentified as Gymnothorax reticularis in China. Because of the special ecological habits and aggressiveness of this species, little research has been performed on its population genetics. Given the general decline in offshore fishery resources, it is necessary to study the genetic characteristics of G. minor in order to protect this resource. In the present study, six different geographical populations of G. minor were collected from their distribution areas in China, and their genetic signatures were investigated for the first time based on the control region fragments. The results showed that G. minor had a very high degree of genetic diversity, and there was no genetic differentiation between these populations. However, the genetic analysis failed to reject panmixia among geographic populations of this species. The life-history characteristics of G. minor and the heterogeneity of its habitat promote the rapid growth of its populations, resulting in gene mutation accumulation and rich genetic diversity. G. minor experienced a population expansion event during the late Pleistocene, which shaped its various genetic signatures. The prolonged pelagic larval duration (PLD) of this species ensures that its leptocephali effectively avoid various physical obstacles and have the opportunity to follow ocean currents to various coastal areas of China. Finally, this moray eel exchanges genetic material with recruitment populations from other locations. All the current genetic signature results for G. minor will serve as a reference for genetic research on moray eels with similar life-history characteristics.

Variations in life history characteristics of the deep-water giant ruby snapper (Etelis sp.) between the Indian and Pacific Oceans and application of a data-poor assessment

The giant ruby snapper, Etelis sp., attains the largest size of any lutjanid in the Indo-Pacific and is one of the most valuable species harvested from deep-water fisheries along the continental and insular shelf margins throughout its broad geographic distribution. Despite this species supporting important commercial, artisanal and subsistence fisheries, quantitative assessments of the status of stocks have been limited by an absence of biological information, unreliable catch and effort statistics, and until recently, misidentification with a cryptic congener. This study aimed, firstly, to describe and compare the age, growth and reproductive characteristics of Etelis sp. between the eastern Indian and western central Pacific Oceans; and secondly, to provide an age-based assessment of the stock in north-western Australia, the only stock for which available data were sufficient to quantify stock status. Although the growth of Etelis sp. differed significantly between sexes and oceans, longevity was similar with a maximum age of 56 years recorded in the Pacific Ocean. Spawning of this species occurred over five months during the austral summer to mid-autumn (i.e. December to April) in the Indian Ocean, but was not well defined in the Pacific Ocean. The estimated ages at 50 % maturity for females and males in the Indian Ocean were similar (i.e. 4–5 years), whereas lengths at 50 % maturity differed (L50mat = 527 and 456 mm fork length, FL, respectively), but were consistent with corresponding differences in growth between sexes. Estimates of the relative female spawning potential ratio for Etelis sp. in north-western Australia suggest the status of this stock remained relatively unchanged from 1997 to 2011, at around 60 % of the unfished level. This assessment provides an example of the relative sustainable exploitation levels for this stock, and potentially other Eteline snappers that exhibit similar life history characteristics, particularly in locations where monitoring and assessments may be data and/or resource limited.

Population genetics of Mesembryanthemum crystallinum in Egypt

Genetic diversity plays an important role in any long term management planning of a species. Mesembryanthemum crystallinum has been naturalized in disturbed regions along the Mediterranean coast competing with native plants. The levels and pattern of the genetic variation within and among its populations along Deltaic Mediterranean coast of Egypt was investigated using random amplified polymorphic DNA (RAPD). Forty‐two samples representing nine populations of M. crystallinum were collected. The results showed that %PPB values for a single population ranged from 9.14% to 28.91% with an average of 19.76%. The average of Shannon information index (SI), expected heterozygosity (He) and unbiased expected heterozygosity (uHe) values were 0.098, 0.064 and 0.072, respectively. According to AMOVA analysis, 9% of the total genetic structure was attributable to regional divergences and 38% to population differentiation within regions and 53% differences among individuals within populations. Mantel test showed a low correlation (r2= 0.001) between the studied populations. The dendrogram exhibited two clusters of populations which were confirmed by principal coordinate analysis (PCoA). The study concluded that M. crystallinum has lower levels of diversity than other plant species with similar life history characteristics and high genetic differentiation among population.

Heterochrony in chimpanzee and bonobo spatial memory development.

The emergence of human-unique cognitive abilities has been linked to our species' extended juvenile period. Comparisons of cognitive development across species can provide new insights into the evolutionary mechanisms shaping cognition. This study examined the development of different components of spatial memory, cognitive mechanisms that support complex foraging, by comparing two species with similar life history that vary in wild ecology: bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). Spatial memory development was assessed using a cross-sectional experimental design comparing apes ranging from infancy to adulthood. Study 1 tested 73 sanctuary-living apes on a task examining recall of a single location after a 1-week delay, compared to an earlier session. Study 2 tested their ability to recall multiple locations within a complex environment. Study 3 examined a subset of individuals from Study 2 on a motivational control task. In Study 1, younger bonobos and chimpanzees of all ages exhibited improved performance in the test session compared to their initial learning experience. Older bonobos, in contrast, did not exhibit a memory boost in performance after the delay. In Study 2, older chimpanzees exhibited an improved ability to recall multiple locations, whereas bonobos did not exhibit any age-related differences. In Study 3, both species were similarly motivated to search for food in the absence of memory demands. These results indicate that closely related species with similar life history characteristics can exhibit divergent patterns of cognitive development, and suggests a role of socioecological niche in shaping patterns of cognition in Pan.

High sensitivity of a keystone forage fish to elevated CO2 and temperature.

Sand lances of the genus Ammodytes are keystone forage fish in coastal ecosystems across the northern hemisphere. Because they directly support populations of higher trophic organisms such as whales, seabirds or tuna, the current lack of empirical data and, therefore, understanding about the climate sensitivity of sand lances represent a serious knowledge gap. Sand lances could be particularly susceptible to ocean warming and acidification because, in contrast to other tested fish species, they reproduce during boreal winter months, and their offspring develop slowly under relatively low and stable pCO2 conditions. Over the course of 2 years, we conducted factorial pCO2 × temperature exposure experiments on offspring of the northern sand lance Ammodytes dubius, a key forage species on the northwest Atlantic shelf. Wild, spawning-ripe adults were collected from Stellwagen Bank National Marine Sanctuary (Cape Cod, USA), and fertilized embryos were reared at three pCO2 conditions (400, 1000 and 2100 μatm) crossed with three temperatures (5, 7 and 10 ˚C). Exposure to future pCO2 conditions consistently resulted in severely reduced embryo survival. Sensitivity to elevated pCO2 was highest at 10 ˚C, resulting in up to an 89% reduction in hatching success between control and predicted end-of-century pCO2 conditions. Moreover, elevated pCO2 conditions delayed hatching, reduced remaining endogenous energy reserves at hatch and reduced embryonic growth. Our results suggest that the northern sand lance is exceptionally CO2-sensitive compared to other fish species. Whether other sand lance species with similar life history characteristics are equally CO2-sensitive is currently unknown. But the possibility is a conservation concern, because many boreal shelf ecosystems rely on sand lances and might therefore be more vulnerable to climate change than currently recognized. Our findings indicate that life history, spawning habitat, phenology and developmental rates mediate the divergent early life CO2 sensitivities among fish species.

Genetic diversity and population genetic structure of the endangered kazakh endemic Oxytropis almaatensis (fabaceae)

The central Asian narrow endemic species Oxytropis almaatensis is a highly endangered plant with a very restricted distribution in the Tian Shan Mountains. In this study, we present the basic conservation genetic characteristics of this species based on a DNA fingerprinting approach in order to provide yardsticks for official conservation agencies to develop an informed conservation strategy. The three currently known populations with two allopatric subpopulations at each site were sampled in the Trans-Ili Alatau Mountains (S Kazakhstan) and subject to AFLP analysis using four primer combinations. This was supplemented by flow cytometry of plants with remarkably different body sizes to check for possible ploidy differences. The presence or absence of AFLP bands was used in downstream analyses utilising various population genetic approaches. Genetic diversity of O. almaatensis was found to be on the upper end of the spectrum typical for other outcrossing species of similar life-history characteristics. Most of the genetic variation was attributable to within (sub)population variance, and we also found a remarkable gene flow between the populations. However, the geographically closer populations were found to be more close to each other genetically, and population differentiation showed the same pattern with a significant isolation by distance. Similar patterns were not found for subpopulations of the geographically more close populations, and the subpopulations living along the same river valley were found to be genetically more cohesive. Flow cytometry did not reveal any difference in DNA content between the small and large forms of the species. All these results suggest the presence of two separate populations at the three localities of this species. Conservation efforts should focus on these two populations, and, given the relatively high genetic diversity within each population, both ex situ and in situ conservation measures can be effectively carried out based on the currently known populations of this narrow endemic species.

The interacting effects of forestry and climate change on the demography of a group-living bird population.

Anthropogenic degradation of natural habitats is a global driver of wildlife population declines. Local population responses to such environmental perturbations are generally well understood, but in socially structured populations, interactions between environmental and social factors may influence population responses. Thus, understanding how habitat degradation affects the dynamics of these populations requires simultaneous consideration of social and environmental mechanisms underlying demographic responses. Here we investigated the effect of habitat degradation through commercial forestry on spatiotemporal dynamics of a group-living bird, the Siberian jay, Perisoreus infaustus, in boreal forests of northern Sweden. We assessed the interacting effects of forestry, climate and population density on stage-specific, seasonal life-history rates and population dynamics, using long-term, individual-based demographic data from 70 territories in natural and managed forests. Stage-specific survival and reproductive rates, and consequently population growth, were lower in managed forests than in natural forests. Population growth was most sensitive to breeder survival and was more sensitive to early dispersing juveniles than those delaying dispersal. Forestry decreased population growth in managed forests by reducing reproductive success and breeder survival. Increased snow depth improved winter survival, and warmer spring temperatures enhanced reproductive success, particularly in natural forests. Population growth was stable in natural forests but it was declining in managed forests, and this difference accelerated under forecasted climate scenarios. Thus, climatic change could exacerbate the rate of forestry-induced population decline through reduced snow cover in our study species, and in other species with similar life-history characteristics and habitat requirements.

Interisland genetic structure of two endangered Hawaiian waterbirds: The Hawaiian Coot and Hawaiian Gallinule

ABSTRACT Most of Hawaii's endemic avifauna are species of conservation concern. Some of Hawaii's endangered waterbirds, however, have increased in number as a result of intensive management of wetlands. To inform these conservation efforts, we examined interisland genetic structure and gene flow within 2 Hawaiian endemic waterbirds, the Hawaiian Coot (Fulica alai) and the Hawaiian subspecies of the Common Gallinule (Gallinula galeata sandvicensis), using microsatellite and mitochondrial loci. Hawaiian Coots and Hawaiian Gallinules occupy coastal wetlands and exhibit similar life history characteristics and generation times, although they may differ in dispersal propensity. Mark–resight data for Hawaiian Coot indicate interisland movements, whereas Hawaiian Gallinules are sedentary. Genetic diversity is partitioned across the landscape differently for Hawaiian Coots and Hawaiian Gallinules; patterns of variation are likely influenced by behavioral and ecological mechanisms. Hawaiian Coots exhibit low level...

Genetic implications of bottleneck effects of differing severities on genetic diversity in naturally recovering populations: An example from Hawaiian coot and Hawaiian gallinule.

The evolutionary trajectory of populations through time is influenced by the interplay of forces (biological, evolutionary, and anthropogenic) acting on the standing genetic variation. We used microsatellite and mitochondrial loci to examine the influence of population declines, of varying severity, on genetic diversity within two Hawaiian endemic waterbirds, the Hawaiian coot and Hawaiian gallinule, by comparing historical (samples collected in the late 1800s and early 1900s) and modern (collected in 2012–2013) populations. Population declines simultaneously experienced by Hawaiian coots and Hawaiian gallinules differentially shaped the evolutionary trajectory of these two populations. Within Hawaiian coot, large reductions (between −38.4% and −51.4%) in mitochondrial diversity were observed, although minimal differences were observed in the distribution of allelic and haplotypic frequencies between sampled time periods. Conversely, for Hawaiian gallinule, allelic frequencies were strongly differentiated between time periods, signatures of a genetic bottleneck were detected, and biases in means of the effective population size were observed at microsatellite loci. The strength of the decline appears to have had a greater influence on genetic diversity within Hawaiian gallinule than Hawaiian coot, coincident with the reduction in census size. These species exhibit similar life history characteristics and generation times; therefore, we hypothesize that differences in behavior and colonization history are likely playing a large role in how allelic and haplotypic frequencies are being shaped through time. Furthermore, differences in patterns of genetic diversity within Hawaiian coot and Hawaiian gallinule highlight the influence of demographic and evolutionary processes in shaping how species respond genetically to ecological stressors.

Conservation and development in conflict: regeneration of wildDavidia involucrata(Nyssaceae) communities weakened by bamboo management in south-central China

AbstractProtected areas, including nature reserves and management areas, are established for the conservation of biological diversity and protection of the associated natural and cultural resources. These objectives, however, are often in conflict with socio-economic development. We investigated the plant communities dominated by the dove treeDavidia involucratain a nature reserve on Mount Jinfo, China, where people intensively manage large areas of bamboo stands. We found a significant lack of small-sized main stems ofD.involucrata(0–25 cm diameter at breast height; height > 1.3 m) and newly emerging sprouts in the reserve. The height-class distribution showed a unimodal pattern, with most individuals (of bothD.involucrataand co-occurring species) concentrated in the 16–28 m height-class, and few individuals in the shrub and sub-canopy layer (1.3–8 m). Existing practices to facilitate the spread of bamboo stands, and the need to develop a local market for bamboo shoots received little consideration when the nature reserve was established in 1979 to protectD.involucrata. To conserveD. involucrataon Mount Jinfo the appropriate authorities and local parties involved in bamboo harvesting need to focus on methods that are favourable to the life history of this and other tree species, and strategies for their regeneration. These methods will also benefit the conservation of other highly valued trees that share similar life-history characteristics withD. involucrata.

Genotype-based estimates of local abundance and effective population size for Hector's dolphins

Conservation and management decisions for wild populations are often based on demographic estimates of abundance (N̂), and less frequently, on genetic estimates of effective population size (N̂e). We used genotype-based methods to estimate both parameters from the same set of biopsy samples, while also providing information on the geographic closure of a local population of Hector's dolphins in Cloudy Bay, New Zealand. The assumption of closure in Cloudy Bay was supported by the lack of genetic differentiation between the two survey years and the absence of any genetically detectable migrants. Using recapture analysis based on genotype identifications, we estimated the abundance of individuals age 1+ (N̂1+) to be 269 (95% CL=233−319, CV=0.12). This was similar to, but more precise than, N̂=230 (95% CL=130−407, CV=0.30) from the more traditional analysis using contemporaneously collected photo-identifications. The N̂e of the parental generation was 191 (95% CL=23−362), and the resulting N̂e/N̂1+ of 0.71 was in reasonable agreement with species of similar life history characteristics. Although N̂e was below the recommended threshold (500, recently increased to ≥1000) thought to be necessary to preserve long-term evolutionary potential in perpetuity, genetic connectivity with neighboring populations on a generational time scale is likely to mitigate the negative effects of low local Ne. Our work demonstrates the breadth of management-relevant information (e.g., N, Ne, sex ratio, genetic diversity, and connectivity to neighboring populations) that can be obtained from a genotype-based analysis, and how conservation implications can change when demographic and genetic population size are considered along with connectivity.

An Analysis of the Interactions Between Weather and Land Use on Midwestern Gamebird Populations Using Historical Data: A Preliminary Report

Concern surrounding species’ abilities to cope with a changing climate and variable land use presents opportunities to look forward toward solutions while investigating historical trends to assess the interaction of land use and weather. Uncertainty surrounding population responses to increased severity and frequency of severe weather associated with climate change presents challenges for making informed management decisions for a suite of already declining bird populations, including huntable populations of socially and economically important game birds, such as northern bobwhite (Colinus virginianus). Historical data are a rich resource for developing a priori hypotheses and models predicting species’ responses to climate change and continued variation in land use. We are utilizing 30 years of historical data to model the responses of northern, ring-necked pheasant (Phasianus colchicus), and wild turkey (Meleagris gallopavo) to land use change and weather within a gradient of land use and climate in Nebraska, Kansas, Iowa, and Missouri. Mixed models incorporating agricultural acreages, relative abundances of gallinaceous birds from the annual Breeding Bird Survey, and historical precipitation and temperature data built at the county-level will illuminate broad scale trends and enable us to draw conclusions about future population responses. We are finding expected differences in population trends between states within a climatic gradient, and varied responses to temperature and precipitation among gallinaceous species, where different annual periods are more or less crucial for different species despite similar life history characteristics. We expect that further modeling will continue to elucidate critical thresholds for birds in the Great Plains in terms of weather and habitat, allowing us to make strong recommendations to managers preparing to deal with the implications of climate change.

Slow life-history traits of a neritic predator, the bronze whaler (Carcharhinus brachyurus)

Intra-species plasticity in the life-history characteristics of sharks leads to the need for regional estimates to accurately determine resilience to anthropogenic effects. The present study provides the first length-at-age, growth and maturity estimates for the bronze whaler (Carcharhinus brachyurus) from southern Australia. Age estimates were obtained from vertebral sections of 466 individuals spanning 50–308-cm total length. Maximum estimates of age for males and females were 25 and 31 years respectively. The three-parameter logistic model for females (L∞=308cm LT, k=0.15, α=742) and for males (L∞=317cm LT, k=0.13, α=782) provided the best fit to the size at age data. Males matured at a similar age (16 years), but smaller size than females (224v. 270cm LT). Growth parameters and age-at-maturity estimates were similar to those for genetically isolated C. brachyurus populations, and the sympatric dusky shark (C. obscurus). The southern Australian C. brachyurus population is long-lived, slow growing and late maturing. These growth parameters are needed to undertake demographic analyses to assess the resilience of C. brachyurus to fishing, and provide an example of a wide-ranging elasmobranch with similar life-history characteristics across isolated populations.

Phytotoxicities of the invasive species Plantago major and non-invasive species Plantago asiatica

Although Plantago major and Plantago asiatica have similar life-history characteristics, P. major populations expand much more rapidly than P. asiatica in habitats where both species occur. One potential factor contributing to this disparity is the production of phytotoxic compounds. However, the phytotoxic characteristics of P. major and P. asiatica have not yet reported. Therefore, we conducted an investigation of possible phytotoxic compounds with allelopathic activity in both species. Aqueous methanol extracts of both plant species inhibited root and hypocotyl growth of garden cress (Lepidium sativum) in a concentration dependent manner. However, the inhibitory effect of P. major was greater than that of P. asiatica. The extracts were further purified by several chromatographic runs and two main phytotoxic compounds were isolated and identified through spectral analysis as (−)-3-hydroxy-β-ionone and blumenol A. (−)-3-Hydroxy-β-ionone and blumenol A inhibited the growth and germination of garden cress at concentrations greater than 1 and 30 μM, respectively. The level of (−)-3-hydroxy-β-ionone in P. major was 7.2-fold greater than that in P. asiatica, while the level of blumenol A was equal in both plant species. Although these Plantago species produce two main phytotoxic compounds with allelopathic activity, the higher level of (−)-3-hydroxy-β-ionone in P. major may result in it contributing the primary inhibitory effects of the extract of P. major. (−)-3-hydroxy-β-ionone may also serve to distinguish the invasive habit of two species and may be involved in the expansion in habitats of P. major.

Competition among native and invasive Impatiens species: the roles of environmental factors, population density and life stage.

Many invasive species are considered competitively superior to native species, with the strongest competition expected in species with similar niches and/or in closely related species. However, competition outcome is strongly context-dependent as competitive strength varies along environmental gradients, and life stages, and also depends on abundances. To explore the importance of these factors, we examined competition effects in an experiment with three Impatiens species (Balsaminaceae) widespread in central Europe and sharing similar life-history characteristics and habitats: the native I. noli-tangere, and two invasive species, I. parviflora and I. glandulifera. We compared their competitive strength and reciprocal impacts under two levels of water and light availability, two overall planting densities and three competitor densities. We assessed species performance (ability to complete the life-cycle, biomass and fecundity) and temporal competition dynamics in a garden pot experiment. Environmental variables had lower explanatory power than overall planting and competitor density, which indicates the importance of competitive interactions when evaluating plant performance and potential invasion success. Despite poor and delayed germination, the invasive I. glandulifera attained dominance even at a high competitor density and was competitively superior across all treatments, exceeding the height of both congeners. Impatiens parviflora was competitively weakest, having a negligible impact on both native I. noli-tangere and invasive I. glandulifera. The intermediate competitive strength of the native I. noli-tangere probably results from its intermediate height, and good germination rate and timing. The difference in height among species increased during the experiment when I. glandulifera was involved; this species continues growing until autumn, enhancing its competitive superiority. The results provide a mechanistic understanding for the competitive exclusion of native I. noli-tangere that occurs in stands with I. glandulifera, but the limited impact of I. parviflora on I. noli-tangere in their mixed stands.

Spawning aggregation behavior and reproductive ecology of the giant bumphead parrotfish, Bolbometopon muricatum, in a remote marine reserve.

The giant bumphead parrotfish (Bolbometopon muricatum) has experienced precipitous population declines throughout its range due to its importance as a highly-prized fishery target and cultural resource. Because of its diet, Bolbometopon may serve as a keystone species on Indo-Pacific coral reefs, yet comprehensive descriptions of its reproductive ecology do not exist. We used a variety of underwater visual census (UVC) methods to study an intact population of Bolbometopon at Wake Atoll, a remote and protected coral atoll in the west Pacific. Key observations include spawning activities in the morning around the full and last quarter moon, with possible spawning extending to the new moon. We observed peaks in aggregation size just prior to and following the full and last quarter moon, respectively, and observed a distinct break in spawning at the site that persisted for four days; individuals returned to the aggregation site one day prior to the last quarter moon and resumed spawning the following day. The mating system was lek-based, characterized by early male arrival at the spawning site followed by vigorous defense (including head-butting between large males) of small territories. These territories were apparently used to attract females that arrived later in large schools, causing substantial changes in the sex ratio on the aggregation site at any given time during the morning spawning period. Aggression between males and courtship of females led to pair spawning within the upper water column. Mating interference was not witnessed but we noted instances suggesting that sperm competition might occur. Densities of Bolbometopon on the aggregation site averaged 10.07(±3.24 SE) fish per hectare (ha) with maximum densities of 51.5 fish per ha. By comparing our observations to the results of biennial surveys conducted by the National Oceanic and Atmospheric Administration (NOAA) Coral Reef Ecosystem Division (CRED), we confirmed spatial consistency of the aggregation across years as well as a temporal break in spawning activity and aggregation that occurred during the lunar phase. We estimated the area encompassed by the spawning aggregation to be 0.72 ha, suggesting that spawning site closures and temporal closures centered around the full to the new moon might form one component of a management and conservation plan for this species. Our study of the mating system and spawning aggregation behavior of Bolbometopon from the protected, relatively pristine population at Wake Atoll provides crucial baselines of population density, sex ratio composition, and productivity of a spawning aggregation site from an oceanic atoll. Such information is key for conservation efforts and provides a basic platform for the design of marine protected areas for this threatened iconic coral reef fish, as well as for species with similar ecological and life history characteristics.