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71.
A large body of research has developed on male ornaments and their role in sexual selection while female ornaments have been less investigated. This study focused on the presence, function, and possible role of a sexually dimorphic nuptial trait as an indicator of female quality in a fish species presenting conventional sex roles: the yellow patch on the belly of Knipowitschia panizzae females. Aquarium spawning experiments demonstrated that this ornament is due to dermal pigments, is displayed only when the female is ready to spawn, and is switched off within minutes from the end of egg deposition. This sexual trait is variable in size among females and indicates female fecundity relative to her own body size. As a consequence, female yellow belly appears to be a reliable indicator of female quality as measured by current fecundity. Field data on natural nests highlights that males usually perform parental care on only one egg batch at a time. The modality of egg deposition suggests that males may be limited in their potential reproductive rates by environmental factors. Male limitations in egg care could favour male choosiness and the evolution of female nuptial displays.Communicated by R. Cattaneo-Vietti, Genova 相似文献
72.
Marco Casu Daniela Casu Tiziana Lai Piero Cossu Marco Curini-Galletti 《Marine Biology》2006,149(5):1163-1174
The giant Mediterranean limpet Patella ferruginea Gmelin, 1791 is an endangered marine gastropod, whose range has progressively shrinked to few, restricted areas, due to intense human exploitation. We have studied the genetic structure of the species, in order to (1) gather information about the levels of genetic variability within and between natural populations of P. ferruginea collected in two Sardinian marine protected areas (MPAs) (Penisola del Sinis—Isola di Mal di Ventre and Isola dell’ Asinara), and (2) make an attempt to find relationships between ecological and biological attributes of the species and the genetic differentiation of the populations studied. The genetic study was carried out by means of the analysis of ten inter-simple sequence repeat (ISSR) primers on a total of 40 individuals collected at four localities. Genetic analysis evidenced (1) medium to high levels of within-population genetic variability, (2) a pattern of genetic structuring that varied with spatial scales, and (3) a strong genetic differentiation between the two MPAs. Although preliminary, these results suggest that gene flow may be present only at very small geographic scale, raising concerns on the future of the conservation of the species. 相似文献
73.
Mart-Jan Schelhaas Geerten Hengeveld Marco Moriondo Gert Jan Reinds Zbigniew W. Kundzewicz Herbert ter Maat Marco Bindi 《Mitigation and Adaptation Strategies for Global Change》2010,15(7):681-701
Risks can generally be described as the combination of hazard, exposure and vulnerability. Using this framework, we evaluated
the historical and future development of risk of fire and wind damage in European forestry at the national level. Fire risk
is expected to increase, mainly as a consequence of an increase in fire hazard, defined as the Fire Weather Index in summer.
Exposure, defined as forest area, is expected to increase slightly as a consequence of active afforestation and abandonment
of marginal agricultural areas. Adaptation options to fire risk should therefore aim to decrease the vulnerability, where
a change in tree species from conifers to broadleaves had most effect. Risk for wind damage in forests is expected to increase
mainly as a consequence of increase in exposure (total growing stock) and vulnerability (defined by age class and tree species
distribution). Projections of future wind climate indicate an increase in hazard (storminess) mainly over Western Europe.
Adaptation options should aim to limit the increase in exposure and vulnerability. Only an increase in harvest level can stop
the current build-up of growing stock, while at the same time it will lower vulnerability through the reduction of the share
of old and vulnerable stands. Changing species from conifers to broadleaves helps to reduce vulnerability as well. Lowering
vulnerability by decreasing the rotation length is only effective in combination with a high demand for wood. Due to data
limitations, no forecast of future fire area or damaged timber amount by storms was possible. 相似文献
74.
75.
Marco A. Aceves-Fernandez J. Carlos Pedraza-Ortega Artemio Sotomayor-Olmedo Juan M. Ramos-Arreguín J. Emilio Vargas-Soto Saul Tovar-Arriaga 《Environmental Modeling and Assessment》2014,19(2):139-152
The use of recurrence plots have been extensively used in various fields. In this work, recurrence plots investigate the changes in the non-linear behaviour of urban air pollution using large datasets of raw data (hourly). This analysis has not been used before to extract information from large datasets for this type of non-linear problem. Two different approaches have been used to tackle this problem. The first approach is to show results according to monitoring network. The second approach is to show the results by particle type. This analysis shows the feasibility of using recurrence analysis for pollution monitoring and control. 相似文献
76.
Jacqueline T. Bangm Jessica L. Reiner Hannes Both Theresa M. Cantu Marco A. Gouws Matthew P. Guillette Jeremy P. Koelmel Wilmien J. Luus-Powell Jan Myburgh Olivia Rynders Joseph R. Sar Willem J. Smit John A. Bowden 《环境科学学报(英文版)》2017,29(11):59-67
This study examined concentrations of 15 perfluoroalkyl acids (PFAAs) in tissues from male Mozambique tilapia (Oreochromis mossambicus) collected at Loskop Dam, Mpumalanga, South Africa in 2014 and 2016. Nine of the 15 PFAAs were detected frequently and were included in statistical analysis and included two of the most commonly known PFAAs, perfluorooctanesulfonic acid (PFOS) (median, 41.6 ng/g) and perfluorooctanoic acid (PFOA) (median, 0.0825 ng/g). Of the tissues measured, plasma (2016 and 2014 median, 22.2 ng/g) contained the highest PFAA burden followed by (in descending order): liver (median, 11.6 ng/g), kidney (median, 9.04 ng/g), spleen (median, 5.92 ng/g), adipose (median, 2.54 ng/g), and muscle (median, 1.11 ng/g). Loskop Dam tilapia have been affected by an inflammatory disease of the adipose tissue known as pansteatitis, so this study also aimed to investigate relationships between PFAA tissue concentrations and incidence of pansteatitis or fish health status. Results revealed that healthy tilapia exhibited an overall higher (p-value < 0.05) PFAA burden than pansteatitis-affected tilapia across all tissues. Further analysis showed that organs previously noted in the literature to contain the highest PFAA concentrations, such as kidney, liver, and plasma, were the organs driving the difference in PFAA burden between the two tilapia groups. Care must be taken in the interpretations we draw from not only the results of our study, but also other PFAA measurements made on populations (human and wildlife alike) under differing health status. 相似文献
77.
Alex Kacelnik Marco Vasconcelos Tiago Monteiro Justine Aw 《Behavioral ecology and sociobiology》2011,65(3):547-558
Charles Darwin aided his private decision making by an explicit deliberation, famously deciding whether or not to marry by
creating a list of points in a table with two columns: “Marry” and “Not Marry”. One hundred seventy-two years after Darwin’s
wedding, we reconsider whether this process of choice, under which individuals assign values to their options and compare
their relative merits at the time of choosing (the tug-of-war model), applies to our experimental animal, the European Starling,
Sturnus vulgaris. We contrast this with the sequential choice model that postulates that decision-makers make no comparison between options
at the time of choice. According to the latter, behaviour in simultaneous choices reflects adaptations to contexts with sequential
encounters, in which the choice is whether to take an opportunity or let it pass. We postulate that, in sequential encounters,
the decision-maker assigns (by learning) a subjective value to each option, reflecting its payoff relative to background opportunities.
This value is expressed as latency and/or probability to accept each opportunity as opposed to keep searching. In simultaneous
encounters, choice occurs through each option being processed independently, by a race between the mechanisms that generate
option-specific latencies. We describe these alternative models and review data supporting the predictions of the sequential
choice model. 相似文献
78.
Patrick Bergeron Stefano Grignolio Marco Apollonio Bill Shipley Marco Festa-Bianchet 《Behavioral ecology and sociobiology》2010,64(8):1299-1307
Social dominance is a fundamental aspect of male evolutionary ecology in polygynous mammals because it determines access to
estrous females. As it is rarely possible to monitor marked individuals of known morphology, little is known about the determinants
of male dominance. We studied the social structure of Alpine ibex males in Gran Paradiso National Park, Italy in 2003, 2006,
and 2007. Dominance interactions produced a linear social hierarchy. In ibex males, body mass and horn length are key traits
in male-male combat, and both increase with age. We explored the links between age, body mass, horn length, and social rank.
Ibex males showed much age-independent phenotypic heterogeneity and rapidly growing males reached high rank at a younger age
than slow-growing males. Because there is no trade-off between horn growth and longevity, fast-growing males may face weak
potential costs of rapid growth and high fitness benefit of achieving high rank. Violent interactions were more likely to
occur between males similar in both mass and horn length, independently of age. We suggest that only high-quality individuals
can afford a strategy of rapid growth for both secondary sexual characters, and likely reap substantial fitness benefits. 相似文献
79.
Marco Ghisalberti 《Environmental Fluid Mechanics》2010,10(3):329-343
Obstructed shear flows (i.e. those over permeable media) are common in the environment. An archetypal example, flow over a
submerged vegetation canopy, is investigated here. Like any flow through complex geometry, canopy flows are characterised
by strong spatial gradients. The focus of this experimental study is the three-dimensionality of aquatic canopy flow, in particular
that of the coherent interfacial vortices that govern mixing into and out of the canopy. It is shown here that the vortices
have a finite lateral scale that is comparable to their vertical scale; both are of the order of the drag length scale of
the canopy, (C
D
a)−1, where a is the frontal area density and C
D
is a bulk drag coefficient. The finite lateral extent of the vortices generates strong lateral hydrodynamic gradients, both
instantaneously and in the long-term. The instantaneous gradients, which can contribute greatly to the dispersion of dissolved
and particulate species, are far more pronounced. Finally, the potential for canopies to generate differential roughness secondary
circulation is examined. In the consideration of vertical scalar transport, this circulation can be of the same order as turbulent
diffusion. 相似文献
80.
Spatial distribution and temporal variation of epibenthic assemblages of coralligenous biogenic rocky outcrops occurring in
the northern Adriatic Sea (45°04′–45°24′N; 12°23′–12°43′E) were investigated by photographic sampling from 2003 to 2006 at
12 randomly selected sites. The dominant reef-forming organisms were the encrusting calcareous algae (Lithophyllum stictaeforme, Lithothamnion minervae and Peyssonnelia polymorpha), while the main bioeroders were boring sponges (Cliona viridis, C. celata, C. thoosina, C. rhodensis, Piona vastifica) and the bivalve Gastrochaena dubia. Composition of the assemblages varied thorough years and among sites. Spatial heterogeneity, at local and regional scale,
prevailed over temporal variation. This variability was related both to the geo-morphological features of the outcrops and
to environmental variables. Sites clearly differed in the percent cover of reef builder and bioeroder species while only limited
temporal variation within site was found. Some taxa revealed complex intra-site temporal trends. These results provide valuable
information on the diversity and variability of epibenthic assemblages of the northern Adriatic coralligenous reefs, essential
for the management and conservation of these unique biogenic habitats. 相似文献