In this study, the plant communities at five succession stages (herbage, herbage-shrub, shrub, tree-shrub, and tree) in the Zhenning Karst Plateau area of Guizhou were examined. The changes of plant functional characteristics in different succession stages were analyzed, as was the relationship between functional traits and environmental factors. The main results include the following. (1) During the succes-sion process, plant height, leaf dry matter mass, leaf area, leaf nitrogen content, and leaf phosphorus content gradually increased, whereas leaf thickness and specific leaf area decreased, and leaf C:P ratio and leaf N:P ratios did not change significantly. (2) Soil organic matter, soil total nitrogen, soil total phosphorus, soil C:N, soil C:P, and soil C:K increased at first and then decreased, reaching a peak at the tree-shrub stage. Soil total potassium fluctuated and soil bulk density gradually decreased and reached the lowest value at the tree-shrub stage. (3) Redundancy analysis (RDA) showed that the plant community shifted from a nutri-ent-poor soil environment to a nutrient-rich environment. Soil total phosphorus, soil C:K, soil organic mat-ter, soil C:N, and soil bulk density were the key environmental factors affecting the change of functional traits. (4) Structural equation modeling suggests that that specific leaf area and leaf nitrogen content had more sensitive responses to soil nutrient resources and environmental factors, respectively.
Trees and shrubs in suburban forest understories can be subject to chronic herbivory from abundant white-tailed deer. An undocumented consequence of this stress may be shifts in secondary metabolite production associated with defense. We aimed to learn whether plants protected from deer exhibited different metabolomic profiles compared to those exposed to deer. We tested the indigenous species Nyssa sylvatica and Lindera benzoin and the invasive, nonindigenous species Rosa multiflora and Euonymus alatus within a suburban forest understory in New Jersey, USA, in unfenced plots and plots fenced for 5.3 years. We did untargeted metabolomics by sampling leaves from three plants of each species per 6-7 fenced and unfenced plots, conducting chloroform-methanol extractions followed by LC-MS/MS, and conducting statistical analysis on Metaboanalyst. We also scored each species for deer browse frequency over eight years, and compared their heights and percent cover between unfenced and fenced plots. The analysis identified 2,333 metabolites. The global metabolome diverged significantly between fenced and unfenced plots pooled across species, but for individual species only N. sylvatica exhibited a significant fencing effect. Nyssa sylvatica was one of the most browsed species and was the only one with both greater cover and height in fenced plots, suggesting greater susceptibility to deer browsing. The metabolites most responsible for the fenced/unfenced divergence also were affected by the species-fencing combination, with increases in certain species but decreases in others. The most significant metabolites that were upregulated in fenced plants include some involved in defense-related metabolic pathways, e.g. monoterpenoid biosynthesis. Further study of more species in multiple sites is needed to learn how common metabolomic responses to deer are among forest species, how the intensity of deer pressure influences the responses, which types of metabolites are most affected, and if there are ecological consequences at the physiological, population, and/or community levels.
Play behavior is a significant trait of immature nonhuman primates (hereafter primates), which may play important roles in sensory, locomotor, socio-cognitive, and developmental processes in primates. It has been suggested that function of play is to practice and improve motor skills related to foraging, avoiding predation, attracting mates, raising offspring, and also is to strength social skills concerning to cementing friendly relationships and defraying aggression among individuals. From September 2009 to August 2010, we investigated play behaviors of 1-12-month-old white-headed langur (Trachypithecus leucocephalus) which is a critically endangered primate endemic to China. During this study, we recorded 4,421 play bouts and 1,302 minutes of play time of 7 infants in total. We found that infants had different play behavior patterns at different ages. Specifically, non-social play behaviors appeared at 1 month of age, social play behaviors at 2 months, and all types of social and non-social play behaviors at 3 months. The frequency and duration of non-social play peaked at 5 months and then decreased, while social play appeared at 2 months and gradually increased with age. Non-social play did not differ between the sexes, whereas social play showed sex specificity, with higher frequency and duration of social play in male infants than in female infants. In addition, male and female white-headed langur infants appeared to prefer the individuals of same sex as social playmates. In conclusion, we first reported the pattern of play behavior of a critically endangered langur aged 1 to 12 months though the sample size is small, our results suggest they may have the adaptation of play behaviors in ages and sexes, which may help them adapt to their habitat and social system.
For more than three decades, the Asian turtle crisis has resulted in the decline of every native species in China. For some species, such as the yellow pond turtle (Mauremys mutica), wild populations have dwindled to near functional extinction. Previous studies show there is deep genetic divergence of M. mutica sensu lato between populations north and south of the Pearl River Drainage but no data to show if phylogeographic structure occurs within these two main types. In this study, we found clear phylogeographic structure. In northern types, we found two main clades, corresponding to mainland China and island clades (Taiwan and Yaeyema Islands) with uncorrected p values of 0.00-2.0% divergence in our 2353 bp concatenated mtDNA data set. For the southern types, we found three main clades corresponding to Hainan, Mainland (Vietnam/Guangxi) and the Annam pond turtle (Mauremys annamensis) with divergence ranging from 1.0-1.8% among these three groups. Moreover, the identification of northern and southern types by phenotype was roughly 98% accurate, which, coupling with the deep genetic divergence in mtDNA (5.5-6.7%) and in the 6056 bp nuDNA data set (0.16-0.37%) provide sufficient evidence for northern M. mutica to be an independent species, and individuals from the southern clade should be regarded as subspecies of M. annamensis. Finally, we provide the most comprehensive database to date which can be used to determine the region of origin for captive stock. Making the large captive populations of M. mutica, under the right conditions, potentially valuable for restocking or augmentation of wild populations.
Plants in suburban forests of eastern North America face the dual stressors of high white-tailed deer density and invasion by nonindigenous plants. The combination of chronic deer herbivory and strong competition from invasive plants could alter a plant’s stress- and defense-related secondary chemistry, especially for long-lived juvenile trees in the understory, but this has not been studied. We measured foliar total antioxidants, phenolics, and flavonoids in juveniles of two native trees, Fraxinus pennsylvanica (green ash) and Fagus grandifolia (American beech), growing in six forests in the suburban landscape of central New Jersey, USA. The trees grew in experimental plots that had been subject for 2.5 years to factorial treatments of deer access/exclosure X addition/no addition of the nonindigenous invasive grass Microstegium vimineum (Japanese stiltgrass). As other hypothesized drivers of plant secondary chemistry, we also measured non-stiltgrass herb layer cover, light levels, and water availability. Univariate mixed model analysis of the deer and stiltgrass effects and multivariate structural equation modeling (SEM) of all variables showed that both greater stiltgrass cover and greater deer pressure induced antioxidants, phenolics, and flavonoids, with some variation between species. Deer were generally the stronger factor, and stiltgrass effects were most apparent at high stiltgrass density. SEM also revealed that soil dryness directly increased the chemicals; deer had additional positive, but indirect, effects via influence on the soil; in beech PAR positively affected flavonoids; and herb layer cover had no effect. Juvenile trees’ chemical defense/stress responses to deer and invasive plants can be protective, but also could have a physiological cost, with negative consequences for recruitment to the canopy. Ecological implications for species and their communities will depend on costs and benefits of stress/defense chemistry in the specific environmental context, particularly with respect to invasive plant competitiveness, extent of invasion, local deer density, and deer browse preferences.
Comparing life history traits among populations that have been separated genetically for several hundred thousand years, but live in similar habitats on different continents, may help us understand how ecological and anthropomorphic factors shape life histories. We compared patterns of growth in body length and mass, and the influence of population density, habitat quality (NDVI), and reproduction on age-specific length and mass of male and female brown bears between Alberta, Canada, and Sweden. We found that Swedish females were significantly smaller in both length and mass than Alberta females. Swedish females also reached primiparity earlier and at a smaller mass and length. However, there were no continental differences in the patterns of growth in males. We found strong positive effects of NDVI, but only weak negative effects of population density on female mass and length in both areas. Generally, especially mass of Alberta females was more strongly affected by NDVI and density than for Swedish females. Reproduction had stronger negative effects on female mass in Alberta than in Sweden. We found no effects of NDVI and population density on male mass and body length in both areas. The larger variation in female growth and size between the areas, in contrast to males, may be related to differences in female reproductive investment due to differences in population trends, i.e., earlier reproduction in increasing populations or populations below carrying capacity, or to different selection pressures in the past, potentially due to human persecution. Swedish females exhibited characteristics typical of increasing populations, whereas Alberta females exhibited characteristics typical of stable or decreasing populations. The difference in reproduction investment means that Swedish bears can be harvested at higher rates, whereas Alberta bears must be managed more conservatively.
Heterosigma akashiwo is a eukaryotic, cosmopolitan, and unicellular alga (class: Raphidophyceae), and produces fish-killing blooms. There is a substantial scientific and practical interest in its ecophysiological characteristics that determine bloom dynamics and its adaptation to broad climate zones. A well-annotated genomic/genetic sequence information enables researchers to characterize organisms using modern molecular technology. The Chloroplast and the mitochondrial genome sequences and transcriptome sequence assembly (TSA) datasets with limited sizes for H. akashiwo are available in NCBI nucleotide database on December 2021: there is no doubt that more genetic information of the species will greatly enhance the progress of biological characterization of the species. Here, we conducted H. akashiwo RNA sequencing, a de novo transcriptome assembly (NCBI TSA ICRV01) of a large number of high-quality short-read sequences, and the functional annotation of predicted genes. Based on our transcriptome, we confirmed that the organism possesses genes that were predicted to function in phagocytosis, supporting the earlier observations of H. akashiwo bacterivory. Along with its capability for photosynthesis, the mixotrophy of H. akashiwo may partially explain its high adaptability to various environmental conditions. Our study here will provide an important toehold to decipher H. akashiwo ecophysiology at a molecular level.
Aim: We have studied population genetic change through time in the Northern dragonhead, Dracocephalum ruyschiana (Lamiaceae); a plant species that has experienced a drastic population decline and habitat loss in Europe. We aimed at adding a historic level to the monitoring of dragonhead by testing a microfluidic SNP array approach on herbarium specimens up to 200 years old and comparing the genomic results with that of modern populations in Norway. We also aimed to gain a more holistic species knowledge to guide monitoring efforts by combining herbarium genomics with ecological niche modelling (ENM). Location: Europe (mainly Norway) Methods: We have applied a microfluidic array consisting of 96 SNP markers on 130 herbarium specimens collected from 1820 to 2008. Obtained genotype data were compared with SNP data from modern samples using various population genetic analyses. We used sample metadata and observational records to model the species’ environmental niche. Results: The SNP array successfully genotyped all included herbarium specimens but was less capable of capturing diversity outside of Norway, which was genetically highly divergent from the Norwegian dragonheads. The historic-modern comparison revealed similar genetic structure in space and limited change through time in Norway. The ENM suggests that dragonhead has not fully achieved its potential distribution in Norway, which is anchored in warmer and drier regions, including areas where it does not occur today. Main conclusions: With the appropriate design procedures, the SNP array technology is promising for genotyping old herbarium specimens; an invaluable source of information from the past. We found no signs of the severe reduction in population size in our temporal genomic data of Norwegian dragonhead. Regardless, the regional populations in Norway are genetically divergent, both from each other and more so from populations outside of Norway, rendering continued protection of all existing populations of the species relevant.
The Timber Rattlesnake (Crotalus horridus) has a large distribution spanning much of the eastern United States. Because temperature, habitat type, prey composition and abundance, and a variety of other factors may dictate reptile behavior, populations of conspecific species may exhibit behavioral differences across latitudinal and elevational gradients. Using radio telemetry, we tracked 10 adult Timber Rattlesnakes (7 males, 3 females) from May 2016 to June 2017 in southeastern Louisiana to examine the spatial ecology of male and non-gravid female snakes. Mean annual and seasonal home ranges of non-gravid female Timber Rattlesnakes were not statistically different from that of males. Mean seasonal home range sizes and average distances travelled of both sexes was smallest in winter, and had a general increasing trend beginning in spring with a peak in fall. These increases seemed to coincide with the breeding season, taking place from early July until the end of November. Comparison of this study with other studies throughout its distribution could have implications towards future management of conservation for other southern populations of Timber Rattlesnakes.
Quantifying habitat quality is dependent on measuring a site’s relative contribution to population growth rate. This is challenging for studies of waterbirds, whose high mobility can decouple demographic rates from local habitat conditions and make sustained monitoring of individuals near-impossible. To overcome these challenges, biologists have used many direct and indirect proxies of waterbird habitat quality. However, consensus on what methods are most appropriate for a given scenario is lacking. We undertook a structured literature review of the methods used to quantify waterbird habitat quality, and provide a synthesis of the context-dependent strengths and limitations of those methods. Our structured search of the Web of Science database returned a sample of 398 studies, upon which our review was based. The reviewed studies assessed habitat quality by either measuring habitat attributes (e.g., food abundance, water quality, vegetation structure), or measuring attributes of the waterbirds themselves (e.g., demographic parameters, body condition, behaviour, distribution). Measuring habitat attributes, although they are only indirectly related to demographic rates, has the advantage of being unaffected by waterbird behavioural stochasticity. Conversely, waterbird-derived measures (e.g., body condition, peck rates) may be more directly related to demographic rates than habitat variables, but may be subject to greater stochastic variation (e.g., behavioural change due to presence of conspecifics). Therefore, caution is needed to ensure that the measured variable does influence waterbird demographic rates. This assumption was usually based on ecological theory rather than empirical evidence. Our review highlighted that there is no single best, universally applicable method to quantify waterbird habitat quality. Individual project specifics (e.g., time frame, spatial scale, funding) will influence the choice of variables measured. Where possible, practitioners should measure variables most directly related to demographic rates. Generally, measuring multiple variables yields a better chance of accurately capturing the relationship between habitat characteristics and demographic rates.
A study on rodent species diversity and community assemblages in West Mt Kilimanjaro was conducted in seven different habitats, covering two dry and wet seasons. Data were collected using a combination of medium-sized Sherman’s live traps, snap and Havarhart traps, for three consecutive nights. General Linear Models (GLM) were used to analyze the effects of predictors (vegetation attributes, seasonality, soil physical properties, disturbance and altitude) on rodent species richness and abundance. Community structure analysis was conducted in the Primer v6 program and Canonical correspondence analysis for habitat association in PAST. A total of 1,393 individuals from 14 species of rodents were trapped. The most dominant rodent species were Rhabdomys pumilioPraomys delectorum, and Lophuromys verhageni which contributed to 68.86% of the total captures. Lophuromys verhageni occurred across all the habitats and seasons. Moreover, habitat types, seasonality, soil texture, ground cover, and altitude significantly influenced rodent species abundance (P< 0.05). Furthermore, habitat types, seasonality and altitude significantly influenced rodent species richness (F8, 759 = 629.7, p< 0.001, R2 = 0.87). In addition to that, two major rodent communities were formed in different habitats. The results show that rodent species richness, abundance, and community assemblages in Mt Kilimanjaro, are a result of change in vegetation structure along the altitudinal gradients. Therefore, information on habitat requirements of multiple species is crucial for the management and conservation of these communities.
The Yunnan-Guizhou Plateau (YGP) is characterized by the distinctive isolated habitat of limestone Karst Islands and features the Wumeng Mountains (Mts), which divide the YGP into the two Plateaus of Yunnan and Guizhou. This study aims to assess the effects of past geographic and environmental isolation and climate fluctuation on the flora distribution in the YGP. To this effect, we analyzed the phylogeographical pattern and genetic structure for Myrica nana, a vulnerable species endemic to the YGP, based on chloroplast and nuclear ribosomal DNA sequence. The results suggest that the genetic and haplotype network structures are divided into at least two groups—cpDNA haplotype H2 (or nrDNA haplotypes h1, h2, and the native haplotype) mainly distributed to the east of the Wumeng Mts, and cpDNA haplotype H1 and haplotypes H3–H10 (or nrDNA haplotype h3) distributed to the west of the Wumeng Mts. A deep genetic split was noted within the two groups to reach 25 steps, especially for the cpDNA fragment variation. The east–west divergence reveals the existence of a natural geographical isolation boundary in the form of the Wumeng Mts, which divides the YGP into the Yunnan and Guizhou Plateaus. Therefore, there existed at least two glacial refugia during the Quaternary glacial period, along with a genetic diversity center, and at least two large geographic protection units for the vulnerable species of M. nana, distributed throughout the eastern and western sides of the Wumeng Mts. This study not only clarifies that the phylogeographical pattern and genetic structure for M. nana can be attributed to geographic and environmental isolation and climate fluctuation, but it also proposes an effective strategy to protect vulnerable species and the important wild flora of the YGP.
Plant phenology is manifested in the seasonal timing of vegetative and reproductive processes, but also has ontogenetic aspects. The adaptive basis of seasonal phenology has been considered mainly in terms of climatic drivers. However, some biotic factors as likely evolutionary influences on plants’ phenology appear to have been under-researched. Several specific cases of putative biotic factors driving plant phenology are outlined, involving both herbivores and pathogens. These illustrate the diversity of likely interactions rather than any systematic coverage or review. Emphasis is on woody perennials, in which phenology is often most multi-faceted and complicated by the ontogenetic aspect. The complete seasonal leaf fall that characterises deciduous plants may be a very important defence against some pathogens. Whether biotic influences drive acquisition or long-term persistence of deciduousness is considered. In one case; of leaf rusts in poplars, countervailing influences of the rusts and climate suggest persistence. Often, however, biotic and environmental influences likely reinforce each other. The timing and duration of shoot flushing may in at least some cases contribute to defences against herbivores, largely through brief periods of ‘predator satiation’ when plant tissues have highest food value. Wide re-examination of plant phenology, accommodating the roles of biotic factors and their interplays with environments as additional adaptive drivers, is advocated, towards developing and applying hypotheses that are observationally or experimentally testable.
There is much concern about disruption of endocrine physiology regulated by steroid hormones in humans, other terrestrial vertebrates and fish by industrial chemicals, such as bisphenol A, and pesticides, such as DDT. These endocrine-disrupting chemicals influence steroid-mediated physiology in humans and other vertebrates by competing with steroids for receptor binding sites, disrupting diverse responses involved in reproduction, development and differentiation. Here I discuss that due to evolution of the progesterone receptor (PR) and mineralocorticoid receptor (MR) after ray-finned fish and terrestrial vertebrates diverged from a common ancestor, each receptor evolved to respond to different steroids in ray-finned fish and terrestrial vertebrates. In elephant shark, a cartilaginous fish, ancestral to ray-finned fish and terrestrial vertebrates, both progesterone and 17,20b-dihydroxy-progesterone activate the PR. During the evolution of ray-finned fish and terrestrial vertebrates, the PR in terrestrial vertebrates continued responding to progesterone and evolved to weakly respond to 17,20b-dihydroxy-progesterone. In contrast, the physiological progestin for the PR in zebrafish and other ray-finned fish is 17,20b-dihydroxy-progesterone, and ray-finned fish PR responds weakly to progesterone. The MR in fish and terrestrial vertebrates also diverged to have different responses to progesterone. Progesterone is a potent agonist for elephant shark MR, zebrafish MR and other fish MRs, in contrast to progesterone's opposite activity as an antagonist for aldosterone, the physiological 2 mineralocorticoid for human MR. These different physiological ligands for fish and terrestrial vertebrate PR and MR need to be considered in applying data for their disruption by chemicals in fish and terrestrial vertebrates to each other.
In U.S. academic institutions, efforts often concentrate on enhancing the recruitment of students from underrepresented groups, focusing on gender and/or race. Yet, non-demographic forms of diversity have received little attention, such as environmental worldviews, i.e., differences in the metaphysical, epistemological, and ethical beliefs that define how humans view, value, and interact with the natural world. Here, we develop an exploratory measure of environmental worldview diversity among undergraduate students enrolled in natural resource related programs. We tested our procedure at Oregon State University, a large public land-grant university in the US. Many students reported metaphysical, epistemological, and/or ethical beliefs that deviate from what has been philosophically characterized as the dominant western worldview of natural resources (anthropocentric, dualistic, hierarchical, utilitarian, mechanistic). Our results suggest that, although forestry students’ environmental worldviews are in some ways more closely aligned with the dominant western worldview than other students in natural resources, generally their worldviews reflect long-term generational shifts away from a strict resource-commodity value orientation, as documented in past research. Our findings highlight the importance of considering environmental worldviews as a dimension of diversity within the new generation natural resource students. Future efforts toward understanding these levels of difference can be important assets in designing programs which appeal to wide variety of students; ultimately helping efforts to recruit and retain a diverse of aspiring natural resource professionals.
Niche partitioning is often vital for the coexistence of ecologically similar species under limited resources. Here I will report the nesting strategy of the two sympatric songbirds and the species differences, which have been overlooked in the past. Blue-capped and red-cheeked cordon-bleus are socially monogamous, biparental songbirds (family Estrildidae) that sympatrically inhabit East Africa. My field observation during their breeding season revealed that red-cheeked cordon-bleus build their nests near wasp nests more frequently than blue-capped cordon-bleus. Blue-capped cordon-bleus instead tended to take over weaver’s old nest more often or use a broader range of nesting materials compared to red-cheeked cordon-bleus. These nesting strategies are already described in the literature as common behaviors in both species. However, the species differences of the adopting strategies have never been reported. While Estrildid finches are one of the best well-studied bird families of their behavior under the captive condition, my finding suggests that we still have limited knowledge of their wild behaviors and ecological plausibility, which is required to understand the functions and evolution.
1. Latitudinal diversity gradient (LDG) is the increase in species richness towards the equator and is one of the most consistent patterns in biogeography, where current and historical processes contribute to shape the pattern. 2. Despite that LDG patterns have been described for some insects, the underlying mechanisms associated with community assembly and diversification along modern latitudinal diversity gradient pattern remain unknowledge for many groups. 3. Odonata is an old order of insects that originated during the Carboniferous and has diversified through different eras. Here, we defined co-occurrence based on the presence in ecoregions and 1°×1° grid cells of Odonata species in North America NA, to address their species richness, phylogenetic structure, and species diversification rate along the latitudinal gradient. 4. For the whole order, we found the highest species richness at mid-latitudes, while phylogenetic diversity showed a linear positive pattern along the gradient. Our results showed dragonfly assemblages were clustered along all the gradient, suggesting that environmental filtering sorted the assemblages. Whereas damselfly species assemblages were clustered at mid-latitude and overdispersed into both extremes of gradient, probably community assembly is driving by thermal gradients at mid-latitude, by competitive exclusion at south extreme, and by different origins of the biota at the boreal zone. Our results show that apparently most ancestral lineages of Odonata inhabit tropical zones, where diversified and dispersed to the temperate region, although likely also have been diversified into regions of NA, which might be linked with the highest species richness at mid-latitude for both suborders.
Animals exhibit variation in their space and time use across an urban-rural gradient. As the top-down influences of apex predators wane due to human-driven declines, landscape level anthropogenic pressures are rising. Human impacts can be analogous to apex predators in that humans can drive increased mortality in both prey species and carnivores, and impact communities through indirect fear effects and food subsidies. Here, we evaluate the time use of a common mesocarnivore across an urban rural gradient, and test whether it is influenced by the intensity of use of a larger carnivore. Using multiple camera-trap surveys, we compared the temporal response of a small carnivore, the raccoon (Procyon lotor), to the larger coyote (Canis latrans) at four sites across Michigan that represented a gradient of pressure from humans. We found that raccoon time use varied by site and was most unique at the rural extreme. Raccoons consistently did not shift their activity pattern in response to coyotes at the site with the highest anthropogenic pressures despite considerable interannual variation, and instead showed the stronger responses to coyotes at more rural sites. Temporal shifts were characterized by raccoons being more diurnal in areas of high coyote activity. We conclude that raccoons do partition time to avoid coyotes. Our results highlight that the variation in raccoon time use across the entirety of the urban-rural gradient needed to be considered, as anthropogenic pressures may dominate and obscure the dynamics of this interaction. In an increasingly anthropocentric world, to understand species interactions, it is imperative that we consider the entire spectrum of human pressures that it may occur within.