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81.
Mangrove species are well adapted to the harsh ecological conditions of their environment throughout the tropics. However,
in the islands of Guadeloupe and Martinique (Lesser Antilles), deficient forest recovery was evidenced in 43 mangrove sites
(>1000 m2) affected by apparently natural tree mortality. Such sites were recorded from four chronological sets of aerial photographs
between 1950 and 1995, and field-investigated in terms of environment and vegetation characteristics. Given the speculative
relationship between the slow-regenerating vegetation and its present environment within non-steady state, disturbed sites,
statistical analyses arbitrarily matching physicochemical and biological data were primarily avoided. On one hand, principal
component analysis (PCA), combined with an agglomerative hierarchical classification, was performed on environmental, rank-ordered
data; on the other hand, multidimensional scaling (MDS) was implemented on vegetation data. Discriminant analyses (DA) further
characterized the environment/vegetation interrelationships for each site type. Ultimately, three main types of mortality
sites have been distinguished among the study areas. One type clustered the sites showing the lowest salinity values and the
highest surge vulnerability whose dominant mangrove species is Rhizophora. Another type presented highly saline sites having clayey soils with pure, stunted, Avicennia stands. The last type consisted of peculiar forest gaps on deep, compact, peat soils. During the rainy season, these sites
turned into shallow ponds scattered with living, young Rhizophora and large, standing, dead Avicennia. The authors suggest that this classification may serve as a comprehensive framework to test subsequent hypotheses (hurricanes,
droughts…) on the origins of natural massive tree mortality and the causes of recovery deficiency in mangroves of the Caribbean. 相似文献
82.
Detection and avoidance of an entomopathogenic fungus by a generalist insect predator 总被引:1,自引:0,他引:1
Abstract. 1. Increasing evidence suggests that insects can assess their environment based on cues related to mortality risks to themselves or their offspring. Limited knowledge is available on such abilities in relation to entomopathogenic fungi, which can cause significant mortality in insect populations. In laboratory bioassays, the ability of the generalist predator Anthocoris nemorum L. (Heteroptera: Anthocoridae) to detect the presence of its natural enemy, the fungal pathogen Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) was investigated.
2. Behavioural observations were conducted on adults of A. nemorum foraging in choice and non-choice arenas treated with conidia suspensions of B. bassiana or just the carrier (control). The arenas consisted either of nettle leaves or soil. Additionally, behaviours in response to sporulating nettle aphid cadavers compared with uninfected aphids or paper balls were evaluated on nettle leaves. An oviposition experiment was also conducted in choice arenas on conidia-treated and untreated nettle leaves.
3. Males and females detected and avoided contact with leaf surfaces inoculated with B. bassiana . Females that were forced to enter fungus-treated leaf surfaces were very reluctant to do so. When females encountered cadavers sporulating with B. bassiana they rapidly withdrew compared with harmless paper ball dummies. Soil inoculated with B. bassiana did not affect A. nemorum behaviour or residence time compared with control soil. Females inserted significantly more eggs in control leaf areas compared with areas treated with B. bassiana conidia.
4. All results suggest that A. nemorum detects and avoids the pathogen B. bassiana when it forages on host plants with which it is adapted but not on soil surfaces. The adaptive significance of detection of entomopathogenic fungi is discussed. 相似文献
2. Behavioural observations were conducted on adults of A. nemorum foraging in choice and non-choice arenas treated with conidia suspensions of B. bassiana or just the carrier (control). The arenas consisted either of nettle leaves or soil. Additionally, behaviours in response to sporulating nettle aphid cadavers compared with uninfected aphids or paper balls were evaluated on nettle leaves. An oviposition experiment was also conducted in choice arenas on conidia-treated and untreated nettle leaves.
3. Males and females detected and avoided contact with leaf surfaces inoculated with B. bassiana . Females that were forced to enter fungus-treated leaf surfaces were very reluctant to do so. When females encountered cadavers sporulating with B. bassiana they rapidly withdrew compared with harmless paper ball dummies. Soil inoculated with B. bassiana did not affect A. nemorum behaviour or residence time compared with control soil. Females inserted significantly more eggs in control leaf areas compared with areas treated with B. bassiana conidia.
4. All results suggest that A. nemorum detects and avoids the pathogen B. bassiana when it forages on host plants with which it is adapted but not on soil surfaces. The adaptive significance of detection of entomopathogenic fungi is discussed. 相似文献
83.
Recent observations suggest that a spreading disease is increasingly contributing to hard coral mortality in the Solitary Islands Marine Park, NSW, Australia. This study determined coral disease prevalence and rate-of-spread through individual affected colonies and investigated the effect this epizootic had on coral populations at sites adjacent to South West Solitary Island. Quantitative data were collected between 2002 and 2004 using photographic and video methods, and visual census along radial arc belt transects. Disease similar to the reported white syndrome and white plague was apparent, spreading through hard coral species from the genera Turbinaria, Acropora, Goniastrea, Pocillopora, Stylophora and Porites. Coral disease prevalence varied between survey dates with mean prevalence increasing from 8.55% during March 2003 to 13.58% in June and declining to 7.75% in September and 6.21% during March 2004. There was a significant difference in mean prevalence between the affected species (p<0.001) and an overall difference between survey dates (p=0.001). Additionally, the rate-of-spread of coral disease through coral colonies determined using repeated, seasonal, still photographs followed similar patterns, with disease progression differing between affected species (p=0.004), and between survey dates (p<0.001). Analysis of the video-transects indicated significant difference in disease prevalence over larger spatial scales (100s of m). However, disease frequency did not vary significantly between 2002 and 2003. 相似文献
84.
Clare McFadden Brianna Muir Marc F. Oxenham 《American journal of physical anthropology》2022,177(2):196-206
In bioarchaeological contexts, a complex relationship exists between infant representation in the age-at-death distribution, gestational and young child mortality rates, and the total fertility rate. The representation of infants in a skeletal sample may be influenced by a range of social, biological, and archaeological factors. To better understand the interactions between representation, fertility, and mortality, this study evaluates the relationship between infant-juvenile age-at-death proportions, fertility rates, and a range of gestational and early childhood mortality measures. The statistical component of this study found the correlation between fertility rates and infant-juvenile proportions was stronger than with any mortality rate variable of interest. This suggests that the proportion of infants in a mortuary sample is a stronger indicator of fertility than it is of infant-juvenile mortality. Social, biological, and archaeological variables potentially influencing infant representation in skeletal samples are discussed and a strongly contextualized and holistic approach to infant and juvenile mortality is recommended. 相似文献
85.
《Animal : an international journal of animal bioscience》2019,13(5):1045-1053
The present study aimed to identify the factors that affect immediate (within 24 h after farrowing onset) postnatal piglet mortality in litters with hyperprolific sows, and investigate their associations with behaviour of postpartum sows in two different farrowing housing systems. A total of 30 sows were housed in: (1) CRATE (n=15): the farrowing crate closed (0.80×2.20 m) within a pen (2.50×1.70 m), and (2) OPEN (n=15): the farrowing crate open (0.80×2.20×1.80 m) within a pen (2.50×2.40 m) with a provision of 20 ls of hay in a rack. A total of 518 live born piglets, produced from the 30 sows, were used for data analyses during the first 24 h after the onset of parturition (T24). Behavioural observations of the sows were assessed via video analyses during T24. Total and crushed piglet mortality rates were higher in OPEN compared with CRATE (P<0.01, for both). During T24, the OPEN sows tended to show higher frequency of postural changes (P=0.07) and duration of standing (P=0.10), and showed higher frequencies of bar-biting (P<0.05) and piglet trapping (P<0.01), when compared with the CRATE sows. During T24, the mortality rates caused by crushing were correlated with the piglet trapping event (r=0.93, P<0.0001), postural changes (r=0.37, P<0.01), duration of standing (r=0.32, P<0.01) and frequency of bar-biting behaviour (r=0.51, P<0.01) of the sows (n=30). In conclusion, immediate postnatal piglet mortality, mainly due to crushing, may be associated with potential increases in frequency of postural changes, duration of standing and incidence of piglet trapping in postpartum sows in the open crate system with large litters. 相似文献
86.
BackgroundMyeloma, one of the most common haematological malignancies worldwide arises in the bone marrow. Incidence rates vary by age and ethnicity but reasons behind these trends are unknown. Treatment of myeloma has changed significantly over recent decades, resulting in longer survival and decreased mortality.MethodsFrom data supplied by the Ministry of Health, all new registrations of and deaths from myeloma between 1985 and 2016 were extracted. Trends in age-specific rates were assessed using the method of Armitage. Age-standardised rates were calculated, and trends in age-adjusted rates analysed using the Mantel-Haenszel extension chi-square test. Age-adjusted incidence and mortality rate ratios were calculated. Myeloma-specific survival was visualised using Kaplan-Meier curves and multivariable hazard ratios calculated using Cox regression.ResultsBetween 1985 and 2016, 7826 New Zealanders were registered with myeloma. Over this time the age-specific incidence of myeloma increased significantly for men, who had higher rates than women. Myeloma mortality was highest in Maori men. Men had higher mortality rates than women in all time periods. Since 1995–1999, mortality has decreased in women whereas in men it has declined since about 2000–2004. Survival has increased significantly since 1990 but Maori still have a higher risk of death than non-Maori.ConclusionThe patterns of variation in myeloma incidence, mortality and survival, as well as their trends over time may be used to assist research into the causes and management of myeloma in New Zealand. 相似文献
87.
BackgroundThere is an undefined relationship between access to regional referral centers and whether the eventual oncologic outcomes are influenced by distance, travel time, or residence in a rural community.MethodsWe used the Surveillance, Epidemiology and End Results (SEER) Program Database to capture all cases of high-grade osteosarcoma from 1990 to 2014 in Iowa, Utah, and New Mexico. Using univariate, Kaplan Meier survival analysis, and multivariate Cox proportional hazards modeling we analyzed patient and tumor characteristics.ResultsA total of 476 patients met the study criteria. There was an increased incidence of metastases for patients residing in a county with a greater than 2 -h drive to the nearest comprehensive cancer center (p = 0.021). Individuals residing in “rural” counties and “very rural” counties showed decreased 5-year survival (p = 0.007 and 0.003, respectively) when compared to those living in areas of higher population density. A multivariate regression analysis showed that the presence of metastasis (HR = 2.78 [95% CI: 1.88–4.10], p < 0.0001) and rural status (HR = 1.58 [95% CI: 1.03–2.43], p = 0.037) were risk factors for mortality when controlling for size of the tumor.ConclusionThe travel time to the nearest comprehensive center was associated with an increased incidence of metastasis on presentation in patients with osteosarcoma. Metastasis and rural status were independent risk factors for mortality. This investigation suggests that individuals living in rural counties may experience barriers to presentation, treatment, or surveillance that are not present in areas with a higher population density. 相似文献
88.
Paulo Eduardo Menezes‐Silva Lucas Loram‐Loureno Rauander Douglas Ferreira Barros Alves Letícia Ferreira Sousa Sabrina Emanuella da Silva Almeida Fernanda Santos Farnese 《Ecology and evolution》2019,9(20):11979-11999
Anthropogenic activities such as uncontrolled deforestation and increasing greenhouse gas emissions are responsible for triggering a series of environmental imbalances that affect the Earth's complex climate dynamics. As a consequence of these changes, several climate models forecast an intensification of extreme weather events over the upcoming decades, including heat waves and increasingly severe drought and flood episodes. The occurrence of such extreme weather will prompt profound changes in several plant communities, resulting in massive forest dieback events that can trigger a massive loss of biodiversity in several biomes worldwide. Despite the gravity of the situation, our knowledge regarding how extreme weather events can undermine the performance, survival, and distribution of forest species remains very fragmented. Therefore, the present review aimed to provide a broad and integrated perspective of the main biochemical, physiological, and morpho‐anatomical disorders that may compromise the performance and survival of forest species exposed to climate change factors, particularly drought, flooding, and global warming. In addition, we also discuss the controversial effects of high CO2 concentrations in enhancing plant growth and reducing the deleterious effects of some extreme climatic events. We conclude with a discussion about the possible effects that the factors associated with the climate change might have on species distribution and forest composition. 相似文献
89.
Julie Landes Pierre‐Yves Henry Isabelle Hardy Martine Perret Samuel Pavard 《Ecology and evolution》2019,9(11):6189-6198
The survival cost of reproduction has been revealed in many free‐ranging vertebrates. However, recent studies on captive populations failed to detect this cost. Theoretically, this lack of survival/reproduction trade‐off is expected when resources are not limiting, but these studies may have failed to detect the cost, as they may not have fully accounted for potential confounding effects, in particular interindividual heterogeneity. Here, we investigated the effects of current and past reproductive effort on later survival in captive females of a small primate, the gray mouse lemur. Survival analyses showed no cost of reproduction in females; and the pattern was even in the opposite direction: the higher the reproductive effort, the higher the chances of survival until the next reproductive event. These conclusions hold even while accounting for interindividual heterogeneity. In agreement with aforementioned studies on captive vertebrates, these results remind us that reproduction is expected to be traded against body maintenance and the survival prospect only when resources are so limiting that they induce an allocation trade‐off. Thus, the cost of reproduction has a major extrinsic component driven by environmental conditions. 相似文献
90.
Global warming is expected to result in earlier emergence of tree seedlings that may experience higher damages and mortality due to late frost in spring. We monitored emergence, characteristics, and survival of seedlings across ten tree species in temperate mixed deciduous forests of Central Europe over one and a half year. We tested whether the timing of emergence represents a trade‐off for seedling survival between minimizing frost risk and maximizing the length of the growing period. Almost two‐thirds of the seedlings died during the first growing period. The timing of emergence was decisive for seedling survival. Although seedlings that emerged early faced a severe late frost event, they benefited from a longer growing period resulting in increased overall survival. Larger seedling height and higher number of leaves positively influenced survival. Seedlings growing on moss had higher survival compared to mineral soil, litter, or herbaceous vegetation. Synthesis. Our findings demonstrate the importance of emergence time for survival of tree seedlings, with early‐emerging seedlings more likely surviving the first growing period. 相似文献