Factors influencing seedling emergence of three global invaders in greenhouses representing major eco‐regions of the world

• Successful germination and seedling emergence in new environments are crucial first steps in the life history of global plant invaders and thus play a key role in processes of range expansion.
• We examined the germination and seedling emergence success of three global plant invaders – Lupinus polyphyllus, Senecio inaequidens and Verbascum thapsus – in greenhouses and climate chambers under climate regimes corresponding to seven eco‐regions. Seed materials were collected from one non‐native population for L. polyphyllus and S. inaequidens, and from 12 populations for V. thapsus (six natives and six non‐natives).
• Experimental climates had significant effects on species responses. No species germinated in the dry (humidity ≤ 50%) and cool (≤ 5 °C) experimental climates. But all species germinated and emerged in two moderately cool (12–19 °C) and in three warm (24–27 °C) experimental climates. In general, V. thapsus showed higher fitness than S. inaequidens and L. polyphyllus. The climate of the seed source region influenced responses of native and non‐native populations of V. thapsus. Non‐native populations of V. thapsus, originating from the warmer seed source, showed higher performance in warm experimental climates and lower performance in moderately cool experimental climates compared to native populations. Responses of V. thapsus populations were also related to precipitation of the seed source region in moderately dry experimental climates.
• The warm, semi‐arid and humid experimental climates are suitable for the crucial first steps of invasion success for L. polyphyllus, S. inaequidens and V. thapsus. The species adaptation to its source region modified the responses of our studied plants under different experimental climates representing major eco‐regions of the world.

     

Demographic consequences of climate variation along an elevational gradient for a montane terrestrial salamander

Climate change represents a significant threat to amphibians. However, for many species, the relationship between demography and climate is unknown, which limits predictive models. Here, we describe the life history variation of Plethodon montanus using capture–recapture data over a period of 4 years, along an elevational gradient to determine how survival and growth vary with climate, and how these relationships vary with elevation. We used a hierarchical model to estimate asymptotic size and growth rate and a spatial Cormack-Jolly-Seber model to estimate the probability of capture and survival and dispersal variance. We found that during the active season, growth and survival rates are both positively affected by precipitation; however, while survival was positively affected by temperature at all elevations, higher temperatures led to a decrease in growth at lower elevations, while at higher elevations the opposite was true. During the inactive season, we found reduced growth rates, whereas survival was lower compared with the active at lower elevations but was higher at higher elevations. Increased inactive season temperatures resulted in decreased survival while we found that temperature, amount of snow, and elevation interacted to influence survival. At low elevations, which were warmer, survival decreased with increasing snowfall but at higher elevations, survival generally increased with increasing snowfall. Our results demonstrate that understanding how the environment can affect salamander demography to develop mechanistic models will require knowledge of the actual environmental conditions experienced by a given population as well as an understanding of the overall differences in climate at a given site.     

Plasticity in functional traits in the context of climate change: a case study of the subalpine forb Boechera stricta (Brassicaceae)

Environmental variation often induces shifts in functional traits, yet we know little about whether plasticity will reduce extinction risks under climate change. As climate change proceeds, phenotypic plasticity could enable species with limited dispersal capacity to persist in situ, and migrating populations of other species to establish in new sites at higher elevations or latitudes. Alternatively, climate change could induce maladaptive plasticity, reducing fitness, and potentially stalling adaptation and migration. Here, we quantified plasticity in life history, foliar morphology, and ecophysiology in Boechera stricta (Brassicaceae), a perennial forb native to the Rocky Mountains. In this region, warming winters are reducing snowpack and warming springs are advancing the timing of snow melt. We hypothesized that traits that were historically advantageous in hot and dry, low‐elevation locations will be favored at higher elevation sites due to climate change. To test this hypothesis, we quantified trait variation in natural populations across an elevational gradient. We then estimated plasticity and genetic variation in common gardens at two elevations. Finally, we tested whether climatic manipulations induce plasticity, with the prediction that plants exposed to early snow removal would resemble individuals from lower elevation populations. In natural populations, foliar morphology and ecophysiology varied with elevation in the predicted directions. In the common gardens, trait plasticity was generally concordant with phenotypic clines from the natural populations. Experimental snow removal advanced flowering phenology by 7 days, which is similar in magnitude to flowering time shifts over 2–3 decades of climate change. Therefore, snow manipulations in this system can be used to predict eco‐evolutionary responses to global change. Snow removal also altered foliar morphology, but in unexpected ways. Extensive plasticity could buffer against immediate fitness declines due to changing climates.     

Differential elevational cline in the phenology and demography of two temporally isolated populations of a damselfly: Not two but one taxon?

1. Temporal isolation by cohort splitting is a life‐history mechanism that has been reported in many temperate insects, including those inhabiting freshwater habitats. Although the cohorts seem to maintain separate temporal niches in a specific location, the temporal isolation may be disrupted across a geographic gradient due to constraints imposed by seasonality. 2. This prediction was tested on two temporally isolated populations of the obligatory univoltine Lestes virens (Odonata, Lestidae) in north‐east Algeria. Although the two cohorts emerge at the same time in spring, one cohort reproduces in summer, while the second cohort estivates in summer and reproduces in autumn. A survey assessing the phenology and abundance was conducted on eight ponds across an elevational gradient (5–1012 m asl) using capture–mark–recapture and adult density sampling. 3. In all sites from low to high elevation, the species showed cohort splitting. The phenology of reproduction of both cohorts showed a delay with elevation, but the cline was 2.2 days for the summer cohort and 0.7 days for the autumn cohort per 100 m of elevation. Moreover, the density of adults in the autumn cohort was higher than that of summer cohort across the entire elevational range, and the difference increased with elevation. 4. These findings regarding the differential elevational cline in the phenology show that the temporal isolation of the two cohorts becomes narrower at high elevation, suggesting potential inter‐cohort temporal overlap at higher elevations. 5. The claim that the two cohorts of L. virens are true temporally isolated species needs further investigation.     

Effects of abiotic factors on the life span of the invasive cordgrass <Emphasis Type="Italic">Spartina densiflora</Emphasis> and the native <Emphasis Type="Italic">Spartina maritima</Emphasis> at low salt marshes

We analyzed variations in the life span of the invasive cordgrass Spartina densiflora at low marshes of SW Iberian Peninsula, and identified the abiotic factors limiting the plant in the absence of competition. With these objectives, clump survivorship, flowering, and growth of S. densiflora were studied in two natural populations at different low marsh elevations during more than three years, and at a transplant experiment in comparison with the native Spartina maritima. The life spans of both cordgrasses changed depending on small variations of a few centimeters in elevation. S. maritima, which tolerates better than S. densiflora the stressful abiotic environment of lower marshes, showed a significant lower distribution limit for its perennial habit, with survivorship longer than three years (from 1997 to 2000), than the neophyte (+1.57 m SHZ vs. +2.00 m SHZ). S. densiflora clumps flowered before dying at mostly all elevations, showing low relative growth rates. In contrast, clumps of S. maritima, with non-viable seeds, only flowered when they were three years old at higher elevations in the low marsh. Our results have applications for salt marshes bioengineering projects and to prevent S. densiflora from invading European marshes since our data improve the knowledge of its colonization mechanisms through salt marsh zonation and so identify those portions of restored and native marshes most susceptible to invasion due to the establishment of perennial populations.     

A long‐term record of Nothofagus dominance in the southern Andes,Chile

Abstract The general model of regeneration dynamics in Nothofagus forests of southern South America could have value in community ecology if predictive relationships between disturbance history, functional traits and site attributes could be identified. Examined here is the proposal that on favourable sites shade‐intolerant Nothofagus are likely not to survive in competition with shade‐tolerant, broad‐leaved evergreen taxa of temperate rain forests, and persistence, thus, is dependent on periodic coarse‐scale disturbance. Comparison of stand dynamics of three old‐growth Nothofagus forests at different elevations in the southern Andes, Chile where deciduous Nothofagus alpina dominates the upper canopy, and examination of the life history trade‐offs of this variation were made. Stem density of all stems ≥5.0 cm d.b.h. was 233–303 stems per hectare, and basal area was 123.9–171.0 m²ha^?1. Maximum lifespan of N. alpina was found to be greater than ca 640 years, exceeding all previously reported ages for this species in the region. Forests had a stable canopy composition for this long‐term, but some appeared to lack effective regeneration of N. alpina in recent years. Regeneration of N. alpina was generally greater in disturbed stands and higher elevation than in undisturbed stands and at lower elevation. Recruitment emerged to be strongly affected by competitive over‐ and understorey associates. There was a gradient of increasing dependence of N. alpina on disturbance towards the more productive end of the environment gradients, and hence less dependence of N. alpina on disturbance for its regeneration towards higher elevation. The study confirms that changes in forest composition may be explained by processes occurring in accordance with the predictions of the existing model of Nothofagus regeneration dynamics, providing stronger evidence specifically directed at mid‐tolerant N. alpina, and by factoring out regeneration dynamics on favourable sites. Thus, for N. alpina, trait differences probably contribute to the competitive advantage over its associates in productive habitats, and may be linked to small‐to‐intermediate‐sized disturbances which inevitably occur as older trees die, enabling N. alpina to persist in forests and therefore maintain species coexistence for the long‐term.     

Thermal adaptations to extreme freeze–thaw cycles in the high tropical Andes

Temperature plays a key role in the biology of ectotherms, including anurans, which are found at higher elevations in the tropics than anywhere in the temperate zone. High elevation tropical environments are characterized by extreme daily thermal fluctuation including high daily maxima and nightly freezing. Our study investigated the contrasting operative temperatures of the anurans Telmatobius marmoratus and Pleurodema marmoratum in different environmental contexts at the same elevation and biome above 5,200 m. Telmatobius marmoratus avoids extremes of daily temperature fluctuation by utilizing thermally buffered aquatic habitat at all life stages, with minimal operative temperature variation (range: 4.6–8.0°C). Pleurodema marmoratum, in contrast, experienced operative temperatures from ?3.5 to 44°C and has one of the widest thermal breadths reported for any tropical frog, from >32°C (critical thermal maximum) to surviving freezing periods of 1 and 6 hr down to ?3.0°C. Our findings expand experimental evidence of frost tolerance in amphibians to the widespread Neotropical family Leptodactylidae, the first such evidence of frost tolerance in a tropical amphibian. Our study identifies three strategies (wide thermal tolerance breadth, use of buffered microhabitats, and behavioral thermoregulation), which allow these tropical frogs to withstand the current wide daily thermal fluctuation above 5,000 m.a.s.l. and which may help them adapt to future climatic changes. Abstract in Spanish is available with online material     

Relationships between alpha diversity of plant species in bloom and climatic variables across an elevation gradient

This study analyzes a 20-year record of flowering observations collected near Tucson, Arizona, USA. In contrast to traditional phenological records, this dataset is a record of all species observed in bloom collected in five segments of approximately 1 mile (1.61 km) in length across a 4,158-ft (1,200-m) elevation gradient. The data showed differing seasonal and interannual patterns, demonstrating the influence of climatic factors and elevation on flowering. Miles at higher elevations showed bloom peaks in summer, consistent with temperate and montane communities. Conversely, lower miles demonstrated two distinct flowering seasons, typical of the surrounding Sonoran Desert. Interannual fluctuations in total species observed in bloom were not consistent across the 5 miles (c. 8 km), suggesting that these communities respond to different flowering cues. Consistent with documented flowering triggers in semi-arid systems, the alpha diversity of species in bloom at lower elevations in this study was strongly influenced by precipitation. Upper elevation bloom numbers were heavily influenced by temperature, correspondent with bloom triggers in temperate and montane systems. In general, different life forms exhibited similar bloom triggers within the study miles, believed to be a function of shallow soils. Multivariate community analyses showed that anomalous climate conditions yielded unique seasonal bloom compositions. Over the course of the study, average summer temperature showed an upward trend; the number of species in bloom in summer (July–October) in the highest mile (1,940–2,210 m) demonstrated a concurrent increasing trend. Community analysis suggested a gradual shift in the composition of species in bloom in this mile over the study period.     

Patterns and drivers of intraspecific variation in avian life history along elevational gradients: a meta‐analysis

Elevational gradients provide powerful natural systems for testing hypotheses regarding the role of environmental variation in the evolution of life‐history strategies. Case studies have revealed shifts towards slower life histories in organisms living at high elevations yet no synthetic analyses exist of elevational variation in life‐history traits for major vertebrate clades. We examined (i) how life‐history traits change with elevation in paired populations of bird species worldwide, and (ii) which biotic and abiotic factors drive elevational shifts in life history. Using three analytical methods, we found that fecundity declined at higher elevations due to smaller clutches and fewer reproductive attempts per year. By contrast, elevational differences in traits associated with parental investment or survival varied among studies. High‐elevation populations had shorter and later breeding seasons, but longer developmental periods implying that temporal constraints contribute to reduced fecundity. Analyses of clutch size data, the trait for which we had the largest number of population comparisons, indicated no evidence that phylogenetic history constrained species‐level plasticity in trait variation associated with elevational gradients. The magnitude of elevational shifts in life‐history traits were largely unrelated to geographic (altitude, latitude), intrinsic (body mass, migratory status), or habitat covariates. Meta‐population structure, methodological issues associated with estimating survival, or processes shaping range boundaries could potentially explain the nature of elevational shifts in life‐history traits evident in this data set. We identify a new risk factor for montane populations in changing climates: low fecundity will result in lower reproductive potential to recover from perturbations, especially as fewer than half of the species experienced higher survival at higher elevations.     

Elevational trends in life histories: revising the pace‐of‐life framework

Life‐history traits in birds, such as lifespan, age at maturity, and rate of reproduction, vary across environments and in combinations imposed by trade‐offs and limitations of physiological mechanisms. A plethora of studies have described the diversity of traits and hypothesized selection pressures shaping components of the survival–reproduction trade‐off. Life‐history variation appears to fall along a slow–fast continuum, with slow pace characterized by higher investment in survival over reproduction and fast pace characterized by higher investment in reproduction over survival. The Pace‐of‐Life Syndrome (POLS) is a framework to describe the slow–fast axis of variation in life‐history traits and physiological traits. The POLS corresponds to latitudinal gradients, with tropical birds exhibiting a slow pace of life. We examined four possible ways that the traits of high‐elevation birds might correspond to the POLS continuum: (i) rapid pace, (ii) tropical slow pace, (iii) novel elevational pace, or (iv) constrained pace. Recent studies reveal that birds breeding at high elevations in temperate zones exhibit a combination of traits creating a unique elevational pace of life with a central trade‐off similar to a slow pace but physiological trade‐offs more similar to a fast pace. A paucity of studies prevents consideration of the possibility of a constrained pace of life. We propose extending the POLS framework to include trait variation of elevational clines to help to investigate complexity in global geographic patterns.     

Between-year variation in seed weights across altitudes in the high-alpine plant <Emphasis Type="Italic">Eritrichium nanum</Emphasis>

Seed weight is a prominent life history trait of plants affecting dispersal, establishment, and survival. In alpine environments, the few studies investigating the effect of elevation on seed weight within species have mainly detected a decrease in seed weight with increasing elevation. This relationship is generally attributed to the adverse climate at high elevations. In order to test this hypothesis, we analyzed seed weight variation across altitudes (2,435–3,055 m a.s.l.) in two consecutive years that differed in weather conditions in the high-alpine cushion plant Eritrichium nanum. We found a significant reduction in seed weight with increasing elevation in both years, but in the growing season with more adverse weather conditions, the reduction was more substantial than in the more favorable year. We conclude that alpine plants may be able to produce well-developed seeds at low elevations in almost all years, independent of weather conditions, whereas reproduction through seeds is potentially limited to years of favorable weather at high elevation.     

Proximate causes of altitudinal differences in body size in an agamid lizard

Body size is directly linked to key life history traits such as growth, fecundity, and survivorship. Identifying the causes of body size variation is a critical task in ecological and evolutionary research. Body size variation along altitudinal gradients has received considerable attention; however, the underlying mechanisms are poorly understood. Here, we compared the growth rate and age structure of toad‐headed lizards (Phrynocephalus vlangalii) from two populations found at different elevations in the Qinghai‐Tibetan Plateau. We used mark‐recapture and skeletochronological analysis to identify the potential proximate causes of altitudinal variation in body size. Lizards from the high‐elevation site had higher growth rates and attained slightly larger adult body sizes than lizards from the low‐elevation site. However, newborns produced by high‐elevation females were smaller than those by low‐elevation females. Von Bertalanffy growth estimates predicted high‐elevation individuals would reach sexual maturity at an earlier age and have a lower mean age than low‐elevation individuals. Relatively lower mean age for the high‐elevation population was confirmed using the skeletochronological analysis. These results support the prediction that a larger adult body size of high‐elevation P. vlangalii results from higher growth rates, associated with higher resource availability.     

Comparisons of recruitment, survival, and growth in invasive and native saplings on a volcano

We monitored the recruitment, survival, and growth of tree saplings on invasive (Larix kaempferi) versus native species (Betula and Populus) using 16 20 m × 20 m plots established along elevation gradient on the volcano Mount Koma, Japan, for 7 years because the sapling behaviors should determine forest structures. The crowding of overstory consists mostly of Larix decreased with increasing elevation. Larix recruits were conspicuous, particularly at middle elevation where overstory crowding was intermediate, while Betula recruits were least. Larix overstory crowding inhibited the recruitment of all the taxa, although intermediate crowding promoted the recruitment of Larix. The restriction of sapling emergence was conspicuous at lower elevation where the overstory crowding was highest, probably because of shading, and/or competition with overstory trees. Sapling recruitment for all taxa was restricted at higher elevation, due to high stresses derived from direct solar radiation and strong wind without overstory. The survival of saplings was 96% for Larix and Betula, while it was ca. 50% for Populus. Larix overstory decreased the survival and growth of all the taxa, except Larix survival and Betula growth. The results implied that Larix could establish by high survival once the recruits succeeded everywhere and native sapling regeneration was restricted by Larix overstory. Strong recruitment, survival, and growth of Larix, together with resistance to overstory crowding, enables it to dominate and persist in such disturbed areas regardless of the canopy closure.     

Life history strategies of cladocerans: comparisons of tropical and temperate taxa

We review recent works on different life history variables of cladoceran taxa in tropical and temperate freshwater bodies, comparing the strategies that cladocerans have evolved to adapt to contrasting environmental conditions in the two geographical regions. These life-history parameters relate to age and size at maturity, survival, fecundity, life-expectancy at birth, lifespan, gross, and net reproductive rates, generation time, the rate of population increase, peak population density and day of peak abundance. We also discuss the role of photoperiod and temperature on some of these life history parameters. We found a general paucity of experimental work and field data in tropics on cladocerans. There is very limited information on the few Daphnia species found in the tropics. The misconception of low species diversity of cladocerans in the tropics arose due to several reasons including lack of extensive and intensive field collections. Higher water temperatures apparently promote permanent infestation of tropical waters with toxic cyanobacteria, which reduce the zooplankton diversity. In addition to higher temperatures in the tropics, the year-round high predation pressure of planktivorous fish probably causes the tropical species, particularly in pelagic habitats, to reach maturity earlier (< 3 days) than in temperate regions. Species of Daphnia in temperate regions are particularly adapted to living at food concentrations that are much lower and seasonably more variable than those for tropical genera such as Diaphanosoma. This is further corroborated by the more than an order of magnitude higher threshold food concentration (TFC) for tropical Cladocera than for their temperate counterparts. Fecundity patterns differ between tropical and temperate cladoceran taxa: cultured under optimal temperature regimes, tropical taxa have fewer eggs than temperate species of a comparable body size. Predation pressure may act differently depending on the size of the cladoceran neonates and thus on their population size structure. Global warming and climate changes seem to affect the behaviour (migration), distribution, and abundance of cladocerans. Apparently, in direct response to these changes, the possibility of encountering the tropical cladocerans in the northern, temperate hemisphere (bioinvasions) is on the rise.     

Differences in carbon stocks along an elevational gradient in tropical mountain forests of Colombia

Tropical mountain forests provide an exceptional opportunity to evaluate the patterns of variation in carbon stocks along elevational gradients that correspond to well‐defined temperature gradients. We predicted that carbon stored in live aboveground biomass, aboveground necromass, and soil components of forests on the eastern flank of the Colombian Andes would change with elevation along this gradient extending from 750 to 2,800 m above sea level. The rationale was that the corresponding change in temperature (14–26°C) would influence tree growth and decomposition of organic matter. To address this hypothesis, we examined the carbon stored in these three components using data from 20 0.25‐ha plots located along this elevational gradient. The mean total carbon stock found in the study region was 241.3 ± 37.5 Mg C/ha. Aboveground carbon stocks decreased with elevation (p = 0.001), as did necromass carbon stocks (p = 0.016). Although soil organic carbon stocks did not differ significantly along the gradient (p = 0.153), they contributed proportionately more at higher than at lower elevations, counterbalancing the opposite trends in aboveground carbon and necromass carbon stocks. As such, total carbon stocks did not vary significantly along the elevational gradient (p = 0.576).     

Ecological interactions among insect herbivores,ants and the host plant Baccharis dracunculifolia in a Brazilian mountain ecosystem

Insect–plant interactions occur in several ways and have considerable environmental and ecological importance. Many feeding strategies have evolved among herbivorous insects, with host–herbivore systems likely being influenced by trophobionts with ants. We investigated how these interactions vary across elevation gradients by evaluating the structure of the herbivorous insect community and ants associated with Baccharis dracunculifolia at three distinct elevations (800, 1100, and 1400 m a.s.l.) on a mountain in southeastern Brazil. Moreover, we evaluated the diversity and specialisation of interactions between herbivores and host plants along the elevational gradient. We sampled herbivores and ants on 60 plants at each elevation (totalling 180 plant individuals). Herbivore species composition differed among elevations, as did interaction diversity and specialisation. Richness and abundance of chewing insects increased with elevation, while β‐diversity among patches of the host plant was higher at the lowest elevation, probably due to the patchy occurrence of B. dracunculifolia. Richness and abundance of sap‐sucking insects were higher at the intermediate elevation, possibly due to local environmental conditions. We observed a positive relationship between ant and herbivore trophobiont richness on B. dracunculifolia. We found that interactions were more specialised and less diverse at higher elevations compared to the lowest elevation. Changes in vegetation and environmental variables shaped species distributions and their ecological interactions along the elevation gradient. Our study demonstrates that increased elevation changes the structure and patterns of interactions of the herbivore insect guilds associated with the host plant B. dracunculifolia. Ant effects depend on the context, the environment, and the species of ants involved, and are essential for the presence of insect trophobionts.     

Temporal variations of mobile carbohydrates in Abies fargesii at the upper tree limits

Low temperatures are associated high‐altitude treelines, but the functional mechanism of treeline formation remains controversial. The relative contributions of carbon limitation (source activity) and growth limitation (sink activity) require more tests across taxa and regions. We examined temporal variations of mobile carbon supply in different tissues of Abies fargesii across treeline ecotones on north‐ and south‐facing slopes of the Qinling Mountains, China. Non‐structural carbohydrate (NSC) concentrations in tissues along the altitudinal gradient on both slopes changed significantly in the early and late growing season, but not in the mid‐growing season, indicating the season‐dependent carbon supply status. Late in the growing season on both slopes, trees at the upper limits had the highest NSC concentrations and total soluble sugars and lowest starch concentrations compared to trees at the lower elevations. NSC concentrations tended to increase in needles and branches throughout the growing season with increasing elevation on both slopes, but declined in roots and stems. NSC concentrations across sampling dates also indicated increases in needles and branches, and decreases in roots and stem with increasing elevation. Overall altitudinal trends of NSC in A. fargesii revealed no depletion of mobile carbon reserves at upper elevation limits, suggesting limitation of sink activity dominates tree life across treeline ecotones in both north‐ and south‐facing slopes. Carbon reserves in storage tissues (especially roots) in the late growing season might also play an important role in winter survival and early growth in spring at upper elevations on both slopes, which define the uppermost limit of A. fargesii.     

Variations in sexual and asexual reproduction of Scirpus mariqueter along an elevational gradient

In order to assess the importance of sexual and asexual reproduction during the life history of Scirpus mariqueter, its reproductive and growth characters were concurrently examined along an elevational gradient (from low elevation to high elevation). The proportions of flowering shoot and inflorescence mass, seed : flower ratio and seed weight were used to quantify the investment in sexual reproduction. The proportions of current-year shoot and rhizome mass were used to quantify the investment in asexual reproduction, and the proportion of corm mass was used for growth, respectively. It was found that vegetative propagation predominated at low elevation, whereas sexual reproduction predominated at high elevation; and that sexual reproduction increased with declining asexual reproduction along the gradient. The results suggest that asexual reproduction is relatively favored in the early life stage, whereas sexual reproduction is favored when the population becomes mature and aged, probably because of the functional differentiation between the two reproductive types. Sexual productive characters (i.e. the proportions of flowering shoot and inflorescence mass) were negatively correlated to both growth and asexual reproductive characters along the gradient, indicating there might exist some trade-offs among growth, sexual and asexual reproduction during the life history. However, no obvious pattern was found between asexual reproductive characters and growth characters along the elevational gradient, possibly because of the varied relationships between them at different life stages. The variations in sexual and asexual reproduction in the species and the relationship between them are thought to be of great significance for local population growth, species persistence and evolution.     

Evidence of exceptional oyster‐reef resilience to fluctuations in sea level

Ecosystems at the land–sea interface are vulnerable to rising sea level. Intertidal habitats must maintain their surface elevations with respect to sea level to persist via vertical growth or landward retreat, but projected rates of sea‐level rise may exceed the accretion rates of many biogenic habitats. While considerable attention is focused on climate change over centennial timescales, relative sea level also fluctuates dramatically (10–30 cm) over month‐to‐year timescales due to interacting oceanic and atmospheric processes. To assess the response of oyster‐reef (Crassostrea virginica) growth to interannual variations in mean sea level (MSL) and improve long‐term forecasts of reef response to rising seas, we monitored the morphology of constructed and natural intertidal reefs over 5 years using terrestrial lidar. Timing of reef scans created distinct periods of high and low relative water level for decade‐old reefs (n = 3) constructed in 1997 and 2000, young reefs (n = 11) constructed in 2011 and one natural reef (approximately 100 years old). Changes in surface elevation were related to MSL trends. Decade‐old reefs achieved 2 cm/year growth, which occurred along higher elevations when MSL increased. Young reefs experienced peak growth (6.7 cm/year) at a lower elevation that coincided with a drop in MSL. The natural reef exhibited considerable loss during the low MSL of the first time step but grew substantially during higher MSL through the second time step, with growth peaking (4.3 cm/year) at MSL, reoccupying the elevations previously lost. Oyster reefs appear to be in dynamic equilibrium with short‐term (month‐to‐year) fluctuations in sea level, evidencing notable resilience to future changes to sea level that surpasses other coastal biogenic habitat types. These growth patterns support the presence of a previously defined optimal growth zone that shifts correspondingly with changes in MSL, which can help guide oyster‐reef conservation and restoration.     

Flowering phenology and reproduction of the Solidago virgaurea L. complex along an elevational gradient on Mt Norikura,central Japan

This study examined the flowering phenology and reproductive traits of the Solidago virgaurea complex at four elevations in the subalpine zone in Japan using a bagging experiment. Flowering started earlier at higher elevations. Syrphid flies mainly visited flowers of the S. virgaurea complex, and the number of visits was considerably lower at the lowest elevation than at the three other elevations. Although the number of seeds per individual did not differ among the four elevations, total achene weight per individual was lower at the lowest elevation than at the three other elevations. The weight of an achene and seed germination rate of the control were much greater at higher elevations than at the lowest elevation. The weight of an achene and germination rate for the control were as low as the bagging treatment at the lowest elevation with infrequent flower visitors, which indicates that the S. virgaurea complex is a facultative outcrosser. The S. virgaurea complex is thought to produce seeds during a short growing season at high elevations by starting to flower earlier, and the large seed size is advantageous for seedling establishment at high elevations. Therefore, elevational changes in flowering phenology and reproductive traits are thought to be an adaptation to the short growing season at high elevations.