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1.
North Atlantic right whales (Eubalaena glacialis Müller 1776) present an interesting problem for abundance and trend estimation in marine wildlife conservation. They are long lived, individually identifiable, highly mobile, and one of the rarest of cetaceans. Individuals are annually resighted at different rates, primarily due to varying stay durations among several principal habitats within a large geographic range. To date, characterizations of abundance have been produced that use simple accounting procedures with differing assumptions about mortality. To better characterize changing abundance of North Atlantic right whales between 1990 and 2015, we adapted a state–space formulation with Jolly‐Seber assumptions about population entry (birth and immigration) to individual resighting histories and fit it using empirical Bayes methodology. This hierarchical model included accommodation for the effect of the substantial individual capture heterogeneity. Estimates from this approach were only slightly higher than published accounting procedures, except for the most recent years (when recapture rates had declined substantially). North Atlantic right whales' abundance increased at about 2.8% per annum from median point estimates of 270 individuals in 1990 to 483 in 2010, and then declined to 2015, when the final estimate was 458 individuals (95% credible intervals 444–471). The probability that the population's trajectory post‐2010 was a decline was estimated at 99.99%. Of special concern was the finding that reduced survival rates of adult females relative to adult males have produced diverging abundance trends between sexes. Despite constraints in recent years, both biological (whales' distribution changing) and logistical (fewer resources available to collect individual photo‐identifications), it is still possible to detect this relatively recent, small change in the population's trajectory. This is thanks to the massive dataset of individual North Atlantic right whale identifications accrued over the past three decades. Photo‐identification data provide biological information that allows more informed inference on the status of this species. 相似文献
2.
Graziella V. DiRenzo Christian Che‐Castaldo Sarah P. Saunders Evan H. Campbell Grant Elise F. Zipkin 《Ecology and evolution》2019,9(2):899-909
Obtaining inferences on disease dynamics (e.g., host population size, pathogen prevalence, transmission rate, host survival probability) typically requires marking and tracking individuals over time. While multistate mark–recapture models can produce high‐quality inference, these techniques are difficult to employ at large spatial and long temporal scales or in small remnant host populations decimated by virulent pathogens, where low recapture rates may preclude the use of mark–recapture techniques. Recently developed N‐mixture models offer a statistical framework for estimating wildlife disease dynamics from count data. N‐mixture models are a type of state‐space model in which observation error is attributed to failing to detect some individuals when they are present (i.e., false negatives). The analysis approach uses repeated surveys of sites over a period of population closure to estimate detection probability. We review the challenges of modeling disease dynamics and describe how N‐mixture models can be used to estimate common metrics, including pathogen prevalence, transmission, and recovery rates while accounting for imperfect host and pathogen detection. We also offer a perspective on future research directions at the intersection of quantitative and disease ecology, including the estimation of false positives in pathogen presence, spatially explicit disease‐structured N‐mixture models, and the integration of other data types with count data to inform disease dynamics. Managers rely on accurate and precise estimates of disease dynamics to develop strategies to mitigate pathogen impacts on host populations. At a time when pathogens pose one of the greatest threats to biodiversity, statistical methods that lead to robust inferences on host populations are critically needed for rapid, rather than incremental, assessments of the impacts of emerging infectious diseases. 相似文献
3.
Elucidating the nature of genetic variation underlying both sexually selected traits and the fitness components of sexual selection is essential to understanding the broader consequences of sexual selection as an evolutionary process. To date, there have been relatively few attempts to connect the genetic variance in sexually selected traits with segregating DNA sequence polymorphisms. We set out to address this in a well‐characterized sexual selection system – the cuticular hydrocarbons (CHCs) of Drosophila serrata – using an indirect association study design that allowed simultaneous estimation of the genetic variance in CHCs, sexual fitness and single nucleotide polymorphism (SNP) effects in an outbred population. We cloned and sequenced an ortholog of the D. melanogaster desaturase 2 gene, previously shown to affect CHC biosynthesis in D. melanogaster, and associated 36 SNPs with minor allele frequencies > 0.02 with variance in CHCs and sexual fitness. Three SNPs had significant multivariate associations with CHC phenotype (q‐value < 0.05). At these loci, minor alleles had multivariate effects on CHCs that were weakly associated with the multivariate direction of sexual selection operating on these traits. Two of these SNPs had pleiotropic associations with male mating success, suggesting these variants may underlie responses to sexual selection due to this locus. There were 15 significant male mating success associations (q‐value < 0.1), and interestingly, we detected a nonrandom pattern in the relationship between allele frequency and direction of effect on male mating success. The minor‐frequency allele usually reduced male mating success, suggesting a positive association between male mating success and total fitness at this locus. 相似文献
4.
Forest loss has been associated with reduced survival in many vertebrates, and previous research on amphibians has mostly focused on effects at early life stages. Paramesotriton hongkongensis is a tropical newt that breeds in streams but spends up to 10 months per year in terrestrial habitats. Populations are threatened by habitat degradation and collection for the pet trade, but the cryptic terrestrial lifestyle of this newt has limited our understanding of its population ecology, which inhibits development of a species‐specific conservation plan. We conducted an eight‐year (2007–2014) mark–recapture study on four P. hongkongensis populations in Hong Kong and used these data to evaluate relationships between forest cover, body size, and rainfall on survival and to estimate population sizes. Hong Kong has been subjected to repeated historic territory‐wide deforestation, and thus, we wanted to determine whether there was a link between forest extent as a proxy of habitat quality and newt demography. Annual survival was positively associated with forest cover within core habitat of all populations and negatively related to body size. Mean annual survival (~60%) was similar to that of other stream‐dwelling amphibians, but varied among years and declined substantially in 2012–2013, perhaps due to illegal collection. Despite the link between forest extent and survival, population sizes declined at the most forested site by 40% and increased by 104% and 134% at two others. Forest protection and consequential secondary succession during recent decades in Hong Kong may have been responsible for persistence of P. hongkongensis populations. 相似文献
5.
Robert E. Ricklefs Leticia Soares Vincenzo A. Ellis Steven C. Latta 《Journal of Biogeography》2016,43(7):1277-1286
6.
Isidro Barela Leslie M. Burger Jimmy Taylor Kristine O. Evans Ryo Ogawa Lance McClintic Guiming Wang 《Ecology and evolution》2020,10(11):4867-4875
Spatial distribution and habitat selection are integral to the study of animal ecology. Habitat selection may optimize the fitness of individuals. Hutchinsonian niche theory posits the fundamental niche of species would support the persistence or growth of populations. Although niche‐based species distribution models (SDMs) and habitat suitability models (HSMs) such as maximum entropy (Maxent) have demonstrated fair to excellent predictive power, few studies have linked the prediction of HSMs to demographic rates. We aimed to test the prediction of Hutchinsonian niche theory that habitat suitability (i.e., likelihood of occurrence) would be positively related to survival of American beaver (Castor canadensis), a North American semi‐aquatic, herbivorous, habitat generalist. We also tested the prediction of ideal free distribution that animal fitness, or its surrogate, is independent of habitat suitability at the equilibrium. We estimated beaver monthly survival probability using the Barker model and radio telemetry data collected in northern Alabama, United States from January 2011 to April 2012. A habitat suitability map was generated with Maxent for the entire study site using landscape variables derived from the 2011 National Land Cover Database (30‐m resolution). We found an inverse relationship between habitat suitability index and beaver survival, contradicting the predictions of niche theory and ideal free distribution. Furthermore, four landscape variables selected by American beaver did not predict survival. The beaver population on our study site has been established for 20 or more years and, subsequently, may be approaching or have reached the carrying capacity. Maxent‐predicted increases in habitat use and subsequent intraspecific competition may have reduced beaver survival. Habitat suitability‐fitness relationships may be complex and, in part, contingent upon local animal abundance. Future studies of mechanistic SDMs incorporating local abundance and demographic rates are needed. 相似文献
7.
There are two long‐standing biogeographic hypotheses regarding the glacial survival of plant species in the Qinghai–Tibetan Plateau (QTP): the in situ survival hypothesis and the tabula rasa hypothesis. We tested these two hypotheses in a phylogeographic study of Rhodiola sect. Prainia, a monophyletic section with ecologically divergent lineages. Molecular data from the nuclear internal transcribed spacer, six plastid markers and 13 nuclear microsatellite loci were analyzed for 240 individuals from 19 populations of this section. Environmental data were used to analyze the niches of major phylogenetic lineages within this section and to model changes in their distributions since the Last Glacial Maximum (LGM). We found that Rhodiola sect. Prainia consists of three evolutionary lineages: all populations of R. stapfii, R. prainii populations at the southern edge of the QTP, and R. prainii populations in the interior part of the QTP. During the LGM, the survival of R. prainii in the interior part of the QTP corresponded with the in situ survival hypothesis, while R. stapfii most probably survived the LGM in a manner corresponding with the tabula rasa hypothesis. The evolutionary history of different lineages of this section was shaped by topography, climate change, and lineage‐specific habitat preferences. 相似文献
8.
Nathalie Kristine Prado Maluta Alberto Fereres João Roberto Spotti Lopes 《Entomologia Experimentalis et Applicata》2017,165(2-3):138-147
Virus infection may change not only the host‐plant phenotypic (morphological and physiological) characteristics, but can also modify the behavior of their insect vector in a mutualistic or rather antagonistic manner, to promote their spread to new hosts. Viruses differ in their modes of transmission and depend on vector behavior for successful spread. Here, we investigated the effects of the semi‐persistently transmitted Tomato chlorosis virus (ToCV, Crinivirus) and the persistent circulative Tomato severe rugose virus (ToSRV, Begomovirus) on alighting preferences and arrestment behavior of their whitefly vector Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Middle East Asia Minor 1 (MEAM1) on tomato plants (Solanum lycopersicum L. cv. Santa Clara, Solanaceae). The vector alighting preferences between infected and uninfected plants in choice assays were apparently influenced by the presence of ToCV and ToSRV in the whiteflies or by their previous exposure to infected plants. The observed changes in vector behavior do not seem to benefit the spread of ToCV: non‐viruliferous insects clearly preferred mock‐inoculated plants, whereas ToCV‐viruliferous insects landed on mock‐inoculated and ToCV‐infected plants, indicating a partial change in insect behavior – ToCV was able to directly affect the preference of its vector B. tabaci, but this change in insect behavior did not affect the virus spread because viruliferous insects landed on mock‐inoculated and infected plants indistinctly. In contrast, ToSRV‐viruliferous insects preferred to land on mock‐inoculated plants, a behavior that increases the probability of spread to new host plants. In the arresting behavior assay, the majority of the insects remained on mock‐inoculated plants when released on them. A greater number of insects moved toward mock‐inoculated plants when initially released on ToCV‐ or ToSRV‐infected plants, suggesting that these viruses may repel or reduce the nutritional quality of the host plants for B. tabaci MEAM1. 相似文献
9.
Zhonghua Jiang Xiaohong Wang Jing Li Hongmei Yang Xin Lin 《Journal of cellular and molecular medicine》2018,22(9):4377-4386
Glycolysis is regarded as the hallmark of cancer development and progression, which involves a multistep enzymatic reaction. This study aimed to explore the clinicopathological significance and potential role of glycolytic enzyme aldolase A (ALDOA) in the carcinogenesis and progression of gastric cancer (GC). ALDOA was screened from three paired liver metastasis tissues and primary GC tissues and further explored with clinical samples and in vitro studies. The ALDOA protein level significantly correlated with a larger tumor diameter (P = .004), advanced T stage (P < .001), N stage (P < .001) and lymphovascular invasion (P = .001). Moreover, the expression of ALDOA was an independent prognostic factor for the 5‐year overall survival and disease‐free survival of patients with GC in both univariate and multivariate survival analyses (P < .05). Silencing the expression of ALDOA in GC cell lines significantly impaired cell growth, proliferation and invasion ability (P < .05). Knockdown of the expression of ALDOA reversed the epithelial–mesenchymal transition process. Mechanically, ALDOA could affect the hypoxia‐inducible factor (HIF)‐1α activity as demonstrated by the HIF‐1α response element–luciferase activity in GC cells. Collectively, this study revealed that ALDOA was a potential biomarker of GC prognosis and was important in the carcinogenesis and progression of human GC. 相似文献
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11.
- Coenagrion mercuriale is rare in the UK and is threatened across Europe. Ischnura pumilio is also threatened in the UK. Both species have suffered population declines in recent years and are vulnerable to habitat fragmentation and loss. Yet, reliable population size and survival estimates are scarce in odonate species. This study provides mark–release–recapture estimates of these parameters for UK stronghold populations of both species.
- Surveys were performed at four locations in southern England between 2001 and 2006. A total of 12 071 adult individuals were marked across nine populations. Mark–release–recapture modelling techniques were used to provide survival and recapture probabilities and population size estimates.
- This study presents the first Horvitz–Thompson estimates of population size in odonates, which are among the highest reported for damselflies. Maximum estimates for a single site were 63 662 ± 4997 for C. mercuriale and 7453 ± 382 for I. pumilio. More males than females were captured at all sites, but calculated estimates indicated a female‐biased sex ratio in adult I. pumilio at one location.
- Daily survival probability is among the highest published for damselflies. Male and female survival was equal or very similar in all populations. Further effects of maturity, age, site, and time on survival were identified.
- Estimated population sizes are much greater than previously thought, suggesting that where habitat is maintained, populations of threatened odonates can be very large. Furthermore, greater proportions of females have been estimated where wider searching techniques were employed. This has implications for future study design if estimates are to be reliably used for conservation management.
12.
Major histocompatibility complex genes (MHC), a gene cluster that controls the immune response to parasites, are regarded as an important determinant of mate choice. However, MHC‐based mate choice studies are especially rare for endangered animals. The giant panda (Ailuropoda melanoleuca), a flagship species, has suffered habitat loss and fragmentation. We investigated the genetic variation of three MHC class II loci, including DRB1, DQA1, and DQA2, for 19 mating‐pairs and 11 parent‐pairs of wild giant pandas based on long‐term field behavior observations and genetic samples. We tested four hypotheses of mate choice based on this MHC variation. We found no supporting evidence for the MHC‐based heterosis, genetic diversity, genetic compatibility and “good gene” hypotheses. These results suggest that giant pandas may not use MHC‐based signals to select mating partners, probably because limited mating opportunities or female‐biased natal dispersal restricts selection for MHC‐based mate choice, acknowledging the caveat of the small sample size often encountered in endangered animal studies. Our study provides insight into the mate choice mechanisms of wild giant pandas and highlights the need to increase the connectivity and facilitate dispersal among fragmented populations and habitats. 相似文献
13.
Parasite modification of host behavior is common, and the literature is dominated by demonstrations of enhanced predation on parasitized prey resulting in transmission of parasites to their next host. We present a case in which predation on parasitized prey is reduced. Despite theoretical modeling suggesting that this phenomenon should be common, it has been reported in only a few host–parasite–predator systems. Using a system of gregarine endosymbionts in host mosquitoes, we designed experiments to compare the vulnerability of parasitized and unparasitized mosquito larvae to predation by obligate predatory mosquito larvae and then compared behavioral features known to change in the presence of predatory cues. We exposed Aedes triseriatus larvae to the parasite Ascogregarina barretti and the predator Toxohrynchites rutilus and assessed larval mortality rate under each treatment condition. Further, we assessed behavioral differences in larvae due to infection and predation stimuli by recording larvae and scoring behaviors and positions within microcosms. Infection with gregarines reduced cohort mortality in the presence of the predator, but the parasite did not affect mortality alone. Further, infection by parasites altered behavior such that infected hosts thrashed less frequently than uninfected hosts and were found more frequently on or in a refuge within the microcosm. By reducing predation on their host, gregarines may be acting as mutualists in the presence of predation on their hosts. These results illustrate a higher‐order interaction, in which a relationship between a species pair (host–endosymbiont or predator–prey) is altered by the presence of a third species. 相似文献
14.
Jennifer Schoberer Eva Liebminger Ulrike Vavra Christiane Veit Alexandra Castilho Martina Dicker Daniel Maresch Friedrich Altmann Chris Hawes Stanley W. Botchway Richard Strasser 《The Plant journal : for cell and molecular biology》2014,80(5):809-822
Golgi‐resident type–II membrane proteins are asymmetrically distributed across the Golgi stack. The intrinsic features of the protein that determine its subcompartment‐specific concentration are still largely unknown. Here, we used a series of chimeric proteins to investigate the contribution of the cytoplasmic, transmembrane and stem region of Nicotiana benthamiana N–acetylglucosaminyltransferase I (GnTI) for its cis/medial‐Golgi localization and for protein–protein interaction in the Golgi. The individual GnTI protein domains were replaced with those from the well‐known trans‐Golgi enzyme α2,6–sialyltransferase (ST) and transiently expressed in Nicotiana benthamiana. Using co‐localization analysis and N–glycan profiling, we show that the transmembrane domain of GnTI is the major determinant for its cis/medial‐Golgi localization. By contrast, the stem region of GnTI contributes predominately to homomeric and heteromeric protein complex formation. Importantly, in transgenic Arabidopsis thaliana, a chimeric GnTI variant with altered sub‐Golgi localization was not able to complement the GnTI‐dependent glycosylation defect. Our results suggest that sequence‐specific features in the transmembrane domain of GnTI account for its steady‐state distribution in the cis/medial‐Golgi in plants, which is a prerequisite for efficient N–glycan processing in vivo. 相似文献
15.
16.
Kristine B. Westergaard Niklaus Zemp Leo P. Bruederle Hans K. Stenien Alex Widmer Simone Fior 《Molecular ecology》2019,28(4):818-832
Quaternary glaciations have played a major role in shaping the genetic diversity and distribution of plant species. Strong palaeoecological and genetic evidence supports a postglacial recolonization of most plant species to northern Europe from southern, eastern and even western glacial refugia. Although highly controversial, the existence of small in situ glacial refugia in northern Europe has recently gained molecular support. We used genomic analyses to examine the phylogeography of a species that is critical in this debate. Carex scirpoidea Michx subsp. scirpoidea is a dioecious, amphi‐Atlantic arctic–alpine sedge that is widely distributed in North America, but absent from most of Eurasia, apart from three extremely disjunct populations in Norway, all well within the limits of the Weichselian ice sheet. Range‐wide population sampling and variation at 5,307 single nucleotide polymorphisms show that the three Norwegian populations comprise unique evolutionary lineages divergent from Greenland with high between‐population divergence. The Norwegian populations have low within‐population genetic diversity consistent with having experienced genetic bottlenecks in glacial refugia, and host private alleles that probably accumulated in long‐term isolated populations. Demographic analyses support a single, pre‐Weichselian colonization into Norway from East Greenland, and subsequent divergence of the three populations in separate refugia. Other refugial areas are identified in North‐east Greenland, Minnesota/Michigan, Colorado and Alaska. Admixed populations in British Columbia and West Greenland indicate postglacial contact. Taken together, evidence from this study strongly indicates in situ glacial survival in Scandinavia. 相似文献
17.
- Coarse woody debris (CWD) in the littoral zone of lakes constitutes a preferred habitat for macroinvertebrates and fish. CWD differs in the surface complexity depending on its decay status. Therefore, CWD may provide distinct types of shelters and thus modify the structure of the macroinvertebrate community as well as its susceptibility to fish predation.
- We ran an enclosure experiment in a lake littoral zone to test the effect of surface complexity of CWD on the interactions between the predator, Eurasian perch (Perca fluviatilis) and its potential macroinvertebrate prey. We deployed 10 enclosures containing fresh wood with a smooth surface and 10 enclosures containing decayed wood with a more complex, rough surface and allowed colonisation by macroinvertebrates. Five enclosures of each type were then stocked by perch and exposed to fish predation.
- The abundance and biomass of macroinvertebrates were significantly higher on decayed wood with greater surface complexity than on fresh wood; however, the type of CWD did not strongly influence the taxonomic composition and diversity of invertebrates.
- The direct effect of perch predation on the macroinvertebrate community was weak. Perch reduced only the abundance of adult Dikerogammarus villosus, while other potential prey, such as chironomids, was more abundant in the presence of the fish. The impact of perch consumption of these larvae was probably obscured by interspecific interactions among chironomids and D. villosus, which were impaired in the fish enclosures.
- We found no clear evidence that the influence of perch on macroinvertebrates was mediated by the complexity of the wood surface. However, fish diet analysis showed that on decayed wood, perch preferentially consumed chironomids, and consumption of D. villosus was much lower, while on fresh wood, the preferential consumption of chironomids decreased with increasing consumption of gammarids. This suggests that such differences in fish diet could be an effect of complex interactions between wood microstructure, prey density and its ability to find refuge in CWD.
- The effect of CWD microstructure on predator–prey interactions was visible with respect to interspecific relationships between chironomids and gammarids, which on more complex decayed wood were moderated in the absence of perch.
18.
H. Shi Q. Zhou X. Liu F. Xie T. Li Q. Zhang H. Dang 《Plant biology (Stuttgart, Germany)》2019,21(1):64-70
- Cold‐adapted trees display acclimation in both carbon source and carbon sink capacity to low‐temperature stress at their upper elevational range limits. Hence a balanced carbon source–sink capacity might be required for their persistence and survival at the elevational tree limits.
- The present study examined the spatial dynamics of carbon source–sink relationship in subalpine fir (Abies fargesii) trees along elevational gradients in the northern slope of the temperate region and in the southern slope of the subtropics in terms of climate in the Qinling Mountain range, north‐central China.
- The results showed that non‐structural carbohydrate (NSC) concentrations in both the source and sink tissues increased with the increase in elevation. The ratio of carbon source–sink displayed a consistent decreasing trend with the increase in elevation and during growing season, showing that it was lowest at a ratio of 2.93 in the northern slope and at a ratio of 2.61 in the southern slope at the upper distribution elevations in the late growing season. Such variations of carbon source–sink ratio might be attributable to the balance between carbon source and sink activities, which changed seasonally across the elevational distribution range.
- We concluded that a ratio of carbon source–sink of at least 2.6 might be essential for subalpine fir trees to persist at their upper range limits. Therefore, a sufficient source–sink ratio and a balanced source–sink relationship might be required for subalpine fir trees to survive and develop at their upper elevational distribution limits.
19.
Ana I. García‐Cervigón Eduardo Velázquez Thorsten Wiegand Adrián Escudero José M. Olano 《植被学杂志》2017,28(3):627-638
20.
Cecily M. Costello Frank T. van Manen Mark A. Haroldson Michael R. Ebinger Steven L. Cain Kerry A. Gunther Daniel D. Bjornlie 《Ecology and evolution》2014,4(10):2004-2018
When abundant, seeds of the high‐elevation whitebark pine (WBP; Pinus albicaulis) are an important fall food for grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem. Rates of bear mortality and bear/human conflicts have been inversely associated with WBP productivity. Recently, mountain pine beetles (Dendroctonus ponderosae) have killed many cone‐producing WBP trees. We used fall (15 August–30 September) Global Positioning System locations from 89 bear years to investigate temporal changes in habitat use and movements during 2000–2011. We calculated Manly–Chesson (MC) indices for selectivity of WBP habitat and secure habitat (≥500 m from roads and human developments), determined dates of WBP use, and documented net daily movement distances and activity radii. To evaluate temporal trends, we used regression, model selection, and candidate model sets consisting of annual WBP production, sex, and year. One‐third of sampled grizzly bears had fall ranges with little or no mapped WBP habitat. Most other bears (72%) had a MC index above 0.5, indicating selection for WBP habitats. From 2000 to 2011, mean MC index decreased and median date of WBP use shifted about 1 week later. We detected no trends in movement indices over time. Outside of national parks, there was no correlation between the MC indices for WBP habitat and secure habitat, and most bears (78%) selected for secure habitat. Nonetheless, mean MC index for secure habitat decreased over the study period during years of good WBP productivity. The wide diet breadth and foraging plasticity of grizzly bears likely allowed them to adjust to declining WBP. Bears reduced use of WBP stands without increasing movement rates, suggesting they obtained alternative fall foods within their local surroundings. However, the reduction in mortality risk historically associated with use of secure, high‐elevation WBP habitat may be diminishing for bears residing in multiple‐use areas. 相似文献