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991.
The "pyroclimatic hypothesis" proposed by F. Biondi and colleagues provides a basis for testable expectations about climatic and other controls of fire regimes. This hypothesis asserts an a priori relationship between the occurrence of widespread fire and values of a relevant climatic index. Such a hypothesis provides the basis for predicting spatial and temporal patterns of fire occurrence based on climatic control. Forests near the Mexico-United States border offer a place to test the relative influence of climatic and other controls in mountain ranges that are ecologically similar and subject to broadly similar top-down climatic influence, but with differing cultural influences. We tested the pyroclimatic hypothesis by comparing fire history information from the Mesa de las Guacamayas, a mountain range in northwestern Chihuahua, with previously published fire data from the Chiricahua Mountains, in southeastern Arizona, approximately 150 km away. We developed a priori hypothetical models of fire occurrence and compared their performance to empirical climate-based models. Fires were frequent at all Mesa de las Guacamayas study sites through the mid-20th century and continued uninterrupted to the present at one site, in contrast to nearly complete fire exclusion after 1892 at sites in the Chiricahua Mountains. The empirical regression models explained a higher proportion of the variability in fire regime associated with climate than did the a priori models. Actual climate-fire relationships diverged in each country after 1892. The a priori models predicted continuing fires at the same rate per century as prior to 1892; fires did in fact continue in Mexico, albeit with some alteration of fire regimes, but ceased in the United States, most likely due to changes in land use. The cross-border comparison confirms that a frequent-fire regime could cease without a climatic cause, supporting previous arguments that bottom-up factors such as livestock grazing can rapidly and drastically alter surface fire regimes. Understanding the historical patterns of climate controls on fire could inform the use of historical data as ecological reference conditions and for future sustainability. 相似文献
992.
The Caspian Sea has no endemic Scyphozoa. In 1999, a mass accumulation of Aurelia medusae was recorded, indicating that sometime earlier, jellyfish had invaded the basin, but since then no scyphozoans have
been reported in the Caspian. In the fall of 2008, we found scyphistomae (scyphoid polyps) during a cruise to the eastern
Middle Caspian. The scyphistomae were numerous (100–10,000 ind. m−2) and occupied a depth range of 30–73 m. Genetic data (18S rDNA, ITS-1 and COI) showed that the scyphistomae belonged to the species A. aurita. The current genetic data set is insufficient to determine the source region(s) of the invasive A. aurita. It remains unclear why no moon jellies have been recorded in the Caspian in the last 10 years. Because swarming scyphomedusae
are often pests, the presence of scyphistomae should be considered as a warning of a possible outbreak of A. aurita medusae in the Caspian. 相似文献
993.
Rui?RebeloEmail author Castro?Barbosa José?P.?Granadeiro Bucar?Indjai Bruno?Novais Gon?alo?M.?Rosa Paulo?Catry 《Marine Biology》2012,159(3):613-620
In marine turtles, the sex of an individual is determined by temperatures experienced during embryonic development. Gonad histological observation is still the only reliable way to determine hatchling sex, hampering the study of reproduction and of the demographic consequences of context-dependent sex-ratios, a subject of interest in a warming planet. We investigated whether hatchling remains from predation by Ocypode cursor can be used to estimate sex-ratio trends in a green turtle rookery at Poilão, Guinea-Bissau (10°52′N, 15°43′W). Sex could be readily determined in 77 and 79% of the predated hatchlings in 2008 and 2009, respectively. By comparing hatchlings killed by crabs, hatchlings accidentally dying on the reefs, and live hatchlings, we show that ghost crabs select the smaller prey, but do not select according to hatchling sex, which is explained by the lack of hatchling size dimorphism in this population. The proportion of male hatchlings was 0.45 ± 0.06 and 0.15 ± 0.06 for early and late-season clutches, respectively, these differences most likely being explained by rainfall. Using leftovers from predation by crabs may be a good solution to non-invasively monitor broad trends in sex-ratios of sea turtles. 相似文献
994.
995.
Multiple traits may either signal different characteristics of a male or be redundant. These multiple signals may convey different
messages if they are intended for different receivers (e.g., male or females) that have different interests. We examined the
functions of multiple colorful visual traits of male Schreiber’s green lizard (Lacerta schreiberi). Results showed that interindividual variation in the characteristics of coloration of males can be related to variation
in morphology, health state, dominance status, and pairing status, but that different relationships were found for each color
signal. For example, dominant males had brighter “blue” throat and with higher values of ultraviolet (UV) and bluish coloration
and darker and greenish dorsal coloration than subordinate males. Health state was also reflected in coloration; males with
a higher immune response had “blue” throats with lower amounts of UV coloration, but had “yellow” chests with higher amounts
of UV coloration. Males found guarding females also differed in coloration from males found alone. These data suggest that
characteristics of coloration of the different multiple signals may reveal different messages for different receivers, either
male or female conspecifics. The development of the different signals, based on different morphological and physiological
mechanisms and trade-offs, may allow signal reliability of multiple colorful traits in different social contexts. 相似文献
996.
Alessandro José Queiroz Sarnaglia Nátaly Adriana Jiménez Monroy Arthur Gomes da Vitória 《Environmental and Ecological Statistics》2018,25(4):443-469
This paper considers the modeling and forecasting of daily maximum hourly ozone concentrations in Laranjeiras, Serra, Brazil, through dynamic regression models. In order to take into account the natural skewness and heavy-tailness of the data, a linear regression model with autoregressive errors and innovations following a member of the family of scale mixture of skew-normal distributions was considered. Pollutants and meteorological variables were considered as predictors, along with some deterministic factors, namely week-days and seasons. The Oceanic Niño Index was also considered as a predictor. The estimated model was able to explain satisfactorily well the correlation structure of the ozone time series. An out-of-sample forecast study was also performed. The skew-normal and skew-t models displayed quite competitive point forecasts compared to the similar model with gaussian innovations. On the other hand, in terms of forecast intervals, the skewed models presented much better performance with more accurate prediction intervals. These findings were empirically corroborated by a forecast Monte Carlo experiment. 相似文献
997.
Oller-Ruiz Ainhoa Garrido Isabel Viñas Pilar Campillo Natalia Fenoll José Hernández-Córdoba Manuel 《Environmental Chemistry Letters》2018,16(3):1077-1082
Environmental Chemistry Letters - There is no previous work on the determination of chlorophenoxy acid herbicides in soils. Here we analysed six chlorophenoxy acid herbicides using magnetic solid... 相似文献
998.
Phylogeographic patterns in Uca annulipes sampled from 30 locations across an East African latitudinal gradient were investigated using mitochondrial DNA cytochrome
oxidase I sequences and analysed together with patterns of morphometric differentiation. Four hundred and four specimens along
the east African coast were sampled, and 18 haplotypes were encountered. Haplotype and nucleotide diversity values were very
low and the phylogenetic analysis did not reveal any clear phylogeographic structure. Furthermore, the analysis of molecular
variance and pairwise Φ
ST values showed no significant spatial population differentiation. Mismatch analyses and tests of neutrality supported the
hypothesis that this species has undergone a fairly recent demographic expansion. Our results, therefore, failed to demonstrate
significant geographical structure in the pattern of genetic variation, indicating that populations of U. annulipes are capable of extensive gene flow among mangroves along the coast. The genetic structure of this species could be panmictic
due to a high amount of gene flow along the geographical gradient in study during the planktonic larval phase, when larvae
are carried along stream by the dominant currents. Moreover, the morphometric analysis performed did not reveal differences
of shape differentiation according to a geographical pattern, although significant differences among the sampling areas were
found. 相似文献
999.
Maria Clara Pessoa Amorim José Miguel Simões Paulo Jorge Fonseca Vitor C. Almada 《Marine Biology》2010,157(3):495-503
In some marine fishes, males migrate from deeper to littoral water to breed, where they defend nests and provide parental
care. In this study, we describe seasonal patterns of shelter occupation in estuarine shallow waters and assess social aggregation
in the Lusitanian toadfish (Batrachoididae), a vocal species with male parental care. Occupation of intertidal shelters was
restricted to the breeding season but adult fish remained in subtidal regions during the non-reproductive season and they
produced sounds throughout the year. Intertidal shelters were aggregated with up to five shelters found per 2-m segment of
an 80-m transect. This aggregation probably resulted from social attraction since many segments were found unoccupied. Moreover,
shelters contained on average two fish (maximum of nine). Based on size, shelters with multiple fish seemed to contain females,
or possibly sneakers, but also more than one type I male inside, indicating a high social tolerance for conspecifics. 相似文献
1000.
José Rafael García-March Miguel Ángel Sanchís Solsona A. M. García-Carrascosa 《Marine Biology》2008,153(4):689-698
Gaping activity of bivalve molluscs is closely related to physiological process such as breathing, nutrition, responses to
environmental stimuli and follows rhythmic cycles in many species. Although the alternation of Sun and Moon is the major entraining
agent for the daily living clock-driven rhythms, cyclic extrinsic environmental factors can also modulate gaping activity.
Therefore, laboratory experimental conditions can alter the natural behaviour of bivalves, hindering the interpretation of
observations. Many features of Pinna nobilis physiology are poorly known, gaping activity not being an exception. To reduce the knowledge gap on this regard, we performed
a study on the species gaping activity. The research was designed to be carried out in situ, in order to avoid the interference
of laboratory conditions in the observations. To this end, we designed and fabricated a new electronic system composed by
a data logger and a sensor formed by multiple reed switches activated by a single magnet. The system is autonomous and can
record gaping activity of subtidal bivalves in potentially any type of subtidal environment. Furthermore, it requires little
framework for the installation. With this system, we monitored 10 individuals in periods ranging between 3 and 21 days, for
up to a total of 98 days. The records have shown that far from being all day open, as previously suggested, P. nobilis follows marked circadian and circalunar rhythms of gaping activity. Individuals usually close the valves during night, sometimes
for more than 12 h. The repetition of patterns observed made it possible to distinguish between two main behaviours: (1) night-closing
related with sunset and (2) night-opening related with the Moon visible in the sky with the disc illuminated more than 50%.
Another two less common trends were also observed: (3) day-closing and (4) night-opening with no visible Moon. 相似文献