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551.
L. E. Browning C. M. Young J. L. Savage D. J. F. Russell H. Barclay S. C. Griffith A. F. Russell 《Behavioral ecology and sociobiology》2012,66(12):1639-1649
Providing food to developing offspring is beneficial for offspring but costly for carers. Understanding patterns of provisioning thus yields important insights into how selection shapes (allo-) parental care strategies. Broadly, offspring development will be influenced by three components of provisioning (prey type, size and delivery rate). However, all three variables are rarely considered simultaneously, leading to suggestions that the results of many studies are misleading. Additionally, few studies have examined the provisioning strategies of breeders and non-breeding helpers in obligate cooperative breeders, wherein reproduction without help is typically unsuccessful. We investigated these components of provisioning in obligately cooperative chestnut-crowned babblers (Pomatostomus ruficeps). Prey type was associated with size, and delivery rate was the best predictor of the overall amount of food provided by carers. As broods aged, breeders and helpers similarly modified the relative proportion of different prey provided and increased both prey size and delivery rate. Breeding females contributed less prey than male breeders and adult helpers, and were the only carers to load-lighten by reducing their provisioning rates in the presence of additional carers. While our results suggest that breeders and helpers follow broadly comparable provisioning rules, they are also consistent with the idea that, in obligately cooperative species, breeding females benefit more from conserving resources for future reproduction than do helpers which have a low probability of breeding independently. 相似文献
552.
Both intraspecific spatial aggregation and temporal priority effects have the potential to increase long-term species coexistence. Theory and models suggest that intraspecific aggregation can facilitate coexistence via limited dispersal or asymmetric interaction distances. During community assembly, intraspecific aggregation may also delay interactions between more and less competitive species, thus creating opportunities for priority effects to facilitate longer-term coexistence. Few empirical studies have tested predictions about aggregation and coexistence, especially in the context of community assembly or ecological restoration. We investigated (1) impacts of intraspecific aggregation on the assembly of eight-species communities over three years, (2) the scale dependence of these impacts, and (3) implications for California prairie restoration. We planted eight native species in each of 19, 5 m wide, octagonal plots. Species were either interspersed throughout the plot or aggregated into eight, 2.2-m(2), wedge-shaped, monospecific sectors. Over three years, species diversity declined more quickly in interspersed plots than in aggregated plots. Two species had higher cover or increased more in interspersed than aggregated plots and were identified as "aggressives." Four species had higher cover or increased more in aggregated than interspersed plots and were identified as "subordinates." Within aggregated plots, aggressive species expanded beyond the sector in which they were originally seeded. Cover of aggressive species increased faster and reached higher values in sectors that were adjacent to the originally planted sector, compared to nonadjacent sectors. Cover of aggressive species also increased more and faster near plot centers, compared to plot edges. Areas near plot centers were representative of smaller aggregation patches since species were planted closer to heterospecific neighbors. Two subordinate species maintained higher cover near plot edges than near plot centers. Moreover, two subordinate species maintained higher cover when seeded in sectors farther away from aggressive species. These results suggest that initial intraspecific aggregation can facilitate species coexistence for at least three years, and larger aggregation patches may be more effective than smaller ones in the face of dispersing dominants. The creation of temporal priority effects may represent an underappreciated pathway by which intraspecific aggregation can increase coexistence. Restorationists may be able to maintain more diverse communities by planting in a mosaic of monospecific patches. 相似文献
553.
Phenotypic plasticity of native vs. invasive purple loosestrife: a two-state multivariate approach 总被引:4,自引:0,他引:4
The differences in phenotypic plasticity between invasive (North American) and native (German) provenances of the invasive plant Lythrum salicaria (purple loosestrife) were examined using a multivariate reaction norm approach testing two important attributes of reaction norms described by multivariate vectors of phenotypic change: the magnitude and direction of mean trait differences between environments. Data were collected for six life history traits from native and invasive plants using a split-plot design with experimentally manipulated water and nutrient levels. We found significant differences between native and invasive plants in multivariate phenotypic plasticity for comparisons between low and high water treatments within low nutrient levels, between low and high nutrient levels within high water treatments, and for comparisons that included both a water and nutrient level change. The significant genotype x environment (G x E) effects support the argument that invasiveness of purple loosestrife is closely associated with the interaction of high levels of soil nutrient and flooding water regime. Our results indicate that native and invasive plants take different strategies for growth and reproduction; native plants flowered earlier and allocated more to flower production, while invasive plants exhibited an extended period of vegetative growth before flowering to increase height and allocation to clonal reproduction, which may contribute to increased fitness and invasiveness in subsequent years. 相似文献
554.
Greg W. Rouse Nerida G. Wilson Shana K. Goffredi Shannon B. Johnson Tracey Smart Chad Widmer Craig M. Young Robert C. Vrijenhoek 《Marine Biology》2009,156(3):395-405
We report observations on spawning and early development in bone-eating worms of the genus Osedax. Individual females of Osedax rubiplumus were observed at 1820 m depth freely spawning hundreds of oocytes, and females of an undescribed species, Osedax “orange collar”, were observed spawning in laboratory aquaria. Cytological and molecular analysis of the spawned oocytes
of two Osedax species revealed no evidence for the bacterial endosymbionts that the female worms require for their nutrition, suggesting
that the bacteria must be acquired later from the environment, as they are in other siboglinids. Individual O. “orange collar” females released an average of 335 (±130) eggs per day, but the number of oocytes spawned per day varied
greatly, suggesting that not all the females spawned daily. Fertilization rates of the spawned oocytes varied from 0 to 100%,
though most females showed nearly 100% fertilization rates. Oocytes spawned in the laboratory at 4–6°C were negatively buoyant.
If fertilized, these oocytes extruded polar bodies and then after at least four hours cleaved unequally. Subsequent cleavages
occurred in a spiral pattern at roughly 2-h intervals, resulting in free-swimming trochophore larvae after 24 h. These lecithotrophic
trochophores swam for 9–16 days before settling with several hooked chaetae, similar to those of dwarf Osedax males. The larval life span of the Osedax species studied in the laboratory appears to be shorter than in closely related Vestimentifera. Osedax rubiplumus, on the other hand, has much larger oocytes and so may have greater dispersal potential than these other Osedax species. The high fecundity and apparently continuous reproduction of Osedax boneworms permits the opportunistic exploitation of sunken vertebrate bones.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
555.
Muscle tissue was collected for stable isotope analysis (SIA) from the main fish predators and their fish and cephalopod prey
from oceanic waters off eastern Australia between 2004 and 2006. SIA of δ15N and δ13C revealed that the species examined could be divided into three main trophic groups. A “top predator” group consisted mainly
of large billfish (Xiphias gladius and Tetrapturus audax), yellowfin (Thunnus albacares), bigeye (T. obesus) and southern bluefin (T. maccoyii) tunas and sharks; with mako (Isurus oxyrinchus) the highest. Below this tier was a second group composed of mid-trophic level fishes including albacore tuna (Thunnus alalunga), lancet fish (Alepisaurus ferox), mahi mahi (Coryphaena hippuris) and ommastrephid squid. Underlying both groups was a grouping of small fishes including myctophids, small scombrids and
nomeids as well as surface fishes including macrorhamphosids. These groupings were based largely on mean animal size which
showed a positive linear relation to δ15N (r
2 = 0.58). Some species showed significant ontogenetic variation in either δ15N (swordfish, lancet fish, yellowfin and albacore tuna) or δ13C (mako shark). We also noted a consistent latitudinal change in δ15N and δ13C at ~28°S for the top predator species, particularly albacore and yellowfin tuna. The differences were consistent with a
change from oligotrophic Coral Sea to nutrient rich Tasman Sea waters. These differences suggest that predatory fishes may
have extended residence time in distinct regions off eastern Australia. 相似文献
556.
Youhua Tang Pius Lee Marina Tsidulko Ho-Chun Huang Jeffery T. McQueen Geoffrey J. DiMego Louisa K. Emmons Robert B. Pierce Anne M. Thompson Hsin-Mu Lin Daiwen Kang Daniel Tong Shaocai Yu Rohit Mathur Jonathan E. Pleim Tanya L. Otte George Pouliot Jeffrey O. Young Kenneth L. Schere Paula M. Davidson Ivanka Stajner 《Environmental Fluid Mechanics》2009,9(1):43-58
A sensitivity study is performed to examine the impact of lateral boundary conditions (LBCs) on the NOAA-EPA operational Air
Quality Forecast Guidance over continental USA. We examined six LBCS: the fixed profile LBC, three global LBCs, and two ozonesonde
LBCs for summer 2006. The simulated results from these six runs are compared to IONS ozonesonde and surface ozone measurements
from August 1 to 5, 2006. The choice of LBCs can affect the ozone prediction throughout the domain, and mainly influence the
predictions in upper altitude or near inflow boundaries, such as the US west coast and the northern border. Statistical results
shows that the use of global model predictions for LBCs could improve the correlation coefficients of surface ozone prediction
over the US west coast, but could also increase the ozone mean bias in most regions of the domain depending on global models.
In this study, the use of the MOZART (Model for Ozone And Related chemical Tracers) prediction for CMAQ (Community Multiscale
Air Quality) LBC shows a better surface ozone prediction than that with fixed LBC, especially over the US west coast. The
LBCs derived from ozonesonde measurements yielded better O3 correlations in the upper troposphere. 相似文献
557.
Walker TR Habeck JO Karjalainen TP Virtanen T Solovieva N Jones V Kuhry P Ponomarev VI Mikkola K Nikula A Patova E Crittenden PD Young SD Ingold T 《Ambio》2006,35(5):220-228
Using interdisciplinary field research in the Usa Basin, northeast European Russia, we compared local inhabitants' perception of environmental problems with chemical and remote-sensing signatures of environmental pollution and their local impacts. Extensive coal mining since the 1930s around Inta and Vorkuta has left a legacy of pollution, detected by measuring snowpack, topsoil, and lichen chemistry, together with remote-sensing techniques and analysis of lake water and sediments. Vorkuta and its environs suffered the worst impacts, with significant metal loading and alkalization in lakes and topsoils, elevated metals and cations in terricolous (reindeer) lichens, and changes in vegetation communities. Although the coal industry has declined recently, the area boasts a booming oil and gas industry, based around Usinsk. Local perceptions and concerns of environmental pollution and protection were higher in Usinsk, as a result of increased awareness after a major oil spill in 1994, compared with Vorkuta's inhabitants, who perceived air pollution as the primary environmental threat. Our studies indicate that the principal sources of atmospheric emissions and local deposition within 25 to 40 km of Vorkuta were coal combustion from power and heating plants, coal mines, and a cement factory. Local people evaluated air pollution from direct observations and personal experiences, such as discoloration of snow and respiratory problems, whereas scientific knowledge played a minor role in shaping these perceptions. 相似文献
558.
Natural and synthesised iron-rich amendments for As and Pb immobilisation in agricultural soil 总被引:1,自引:0,他引:1
Yaser A. Almaroai Meththika Vithanage Anushka Upamali Rajapaksha Sang Soo Lee Xiaomin Dou Young Han Lee 《Chemistry and Ecology》2014,30(3):267-279
The immobilisation of heavy metals in contaminated soils is a promising alternative to conventional remediation techniques. Very few studies have focused on the use of iron-rich nanomaterials and natural materials for the adsorption of toxic metals in soils. Synthesised iron-rich nanomaterials (Fe and Zr–Fe oxides) and natural iron-rich materials (natural red earth; NRE) were used to immobilise As and Pb in contaminated agricultural soil. Total concentrations of As and Pb in the initial soil (as control) were 170.76 and 1945.11 mg kg?1, respectively. Amendments were applied into the soil at 1, 2.5 and 5% (w/w) in triplicate and incubated for 150 days. Except for the NRE-amended soil, soil pH decreased from 5.6 to 4.9 with increasing application rates of Fe and Zr–Fe oxides. With addition of Fe and Zr–Fe oxides at 5%, the ammonium acetate (NHO4Ac)-extractable Pb was greatly decreased by 83 and 65% compared with NRE addition (43%). All subjected amendments also led to a decrease in NHO4Ac-extractable As in the soils, indicating the high capacity of As immobilisation. Soil amended with NRE showed a lower ratio of cy19:0 to 18:1ω7c, indicating decreased microbial stress. The toxicity characteristic leaching procedure produced results similar to the NHO4Ac extraction for As and Pb. The NRE addition is recommended for immobilising heavy metals and maintaining biological soil properties. 相似文献
559.
Xavier A. Harrison Jennifer E. York Dominic L. Cram Michelle C. Hares Andrew J. Young 《Behavioral ecology and sociobiology》2013,67(12):1915-1929
The distribution of reproductive success within societies is a key determinant of the outcomes of social evolution. Attempts to explain social diversity, therefore, require that we quantify reproductive skews and identify the mechanisms that generate them. Here, we address this priority using life history and genotypic data from >600 individuals in 40 wild groups of the cooperatively breeding white-browed sparrow weaver, Plocepasser mahali. We show that groups comprise up to six males and seven females, but within-group reproduction is completely monopolised by a single dominant male and female, while extra-group males sire 12–18 % of offspring. Strong within-group kin structure could frequently explain these monopolies, as subordinates had typically delayed dispersal from their natal groups and so frequently (1) lacked within-group outbreeding partners, and/or (2) stood to gain little from contesting dominant reproduction, being almost as related to the dominant’s young as they would have been to their own. Kin structure alone cannot account entirely for these monopolies, however, as they remained complete following the immigration of unrelated males and females. That subordinate females remain reproductively quiescent despite also showing comparable body condition to dominants, overlapping them substantially in age, and showing no evidence of elevated stress hormone levels raises the possibility that they exercise reproductive restraint due instead to a threat of action by dominants and/or deficits in offspring fitness that might arise if subordinates bred. Our findings highlight the complexity of the mechanisms that generate reproductive disparities in animal societies and the challenge of identifying them when skews are complete. 相似文献
560.