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991.
S.?P.?PerryEmail author T.?W.?Chapman M.?P.?Schwarz B.?J.?Crespi 《Behavioral ecology and sociobiology》2004,56(6):602-610
The essence of eusociality is a trade-off between producing ones own offspring and helping collateral kin via such activities as defence, foraging and brood rearing. This trade-off often involves morphological differences between helper and reproductive castes, but the advantages, correlates and phylogenetic context of morphological caste differentiation have seldom been analysed. Six species of Australian gall-inducing thrips on Acacia show morphological polymorphism. One morph, referred to as a soldier, has reduced wings and antennae but greatly enlarged fore-femora, which are thought to be adaptations for gall defence. The other, dispersing morph, has fully developed wings and relatively slight fore-femora. Here, we quantify the defensive behaviour of soldier morphs, and compare soldier and foundresses, using behavioural assays designed to measure proclivity to attack kleptoparasites (specialised invaders in the genus Koptothrips) and effectiveness in killing them. In all five species investigated, soldiers were able to kill Koptothrips. Moreover, the effectiveness of soldiers was relatively high in the more-derived species in the phylogeny of the clade, Kladothrips intermedius, K. habrus and K. waterhousei. Soldiers of K. intermedius and K. habrus also killed kleptoparasites more effectively than did foundresses, and K. habrus soldiers exhibited higher proclivity to attack than did foundresses. Data from naturally invaded galls demonstrate that soldiers in the field do kill Koptothrips, and vice versa. These results show that soldiers of Australian gall thrips are motivated and effective for gall defence.Communicated by D. Gwynne 相似文献
992.
Zooplankton biomass and indices of grazing and metabolism during a late winter bloom in subtropical waters 总被引:3,自引:0,他引:3
S.?Hernández-LeónEmail author C.?Almeida P.?Bécognée L.?Yebra J.?Arístegui 《Marine Biology》2004,145(6):1191-1200
The development of the so-called late winter bloom in subtropical water was studied in an oceanic area north of the Canary Islands from January to May 2000. Zooplankton was sampled at short-term intervals (1–4 days) during the bloom (January–March), and biomass, indices of grazing (gut fluorescence) and metabolism (electron transfer system activity, ETS) were measured in four different size fractions (100–200, 200–500, 500–1000 and >1000 µm). During the bloom, ETS activity and gut fluorescence increased before the development of zooplankton biomass. At the end of February, the presence of an impressive cloud of dust formed in the Sahara desert was related to an increase in chlorophyll and small zooplankton a week later. The increments in biomass were the consequence of consumption by zooplankton as inferred from the indices of grazing and metabolism. Estimated grazing from gut fluorescence and gut evacuation rates during the period of study accounted for 55% of the assessed total ingestion from respiration and normal values of assimilation, showing the importance of the non-pigmented food in the diet of zooplankton in these waters. In contrast, the sharp decreases in zooplankton biomass observed during the bloom appeared during the dark period of the moon, the days in which the diel vertical migrants reach the shallower layers, in agreement with previous works in the area. Thus, the development of the late winter bloom in this region is suggested to be driven by the interplay between resource and consumer controls.Communicated by S.A. Poulet, Roscoff 相似文献
993.
C.?A.?Milbury D.?W.?Meritt R.?I.?E.?Newell P.?M.?GaffneyEmail author 《Marine Biology》2004,145(2):351-359
Overharvesting, habitat degradation, and disease have resulted in a century of decline for Atlantic Coast populations of the eastern oyster Crassostrea virginica (Gmelin). The introduction of oysters with superior disease resistance (e.g. oysters from different geographical areas, or genetically improved strains) may be useful in restoration efforts. In 1997 the Oyster Recovery Partnership and the University of Maryland Center for Environmental Science planted more than four million Louisiana oysters in the Choptank River, which flows into the Chesapeake Bay, Maryland, USA. These oysters, which may be distinguished from Atlantic oysters by diagnostic single-nucleotide polymorphisms (SNPs) in their mitochondrial DNA, were expected to display enhanced survival and reproduction as a result of their superior resistance to Dermo disease. A high-throughput, synthesis-by-sequencing technique (Pyrosequencing) was used to determine the mitochondrial haplotypes of spat collected in the Choptank River and nearby regions of the bay. Of 3,545 spat collected in 1999, 2000, and 2001, 3,349 (94.47%) possessed the North Atlantic haplotype, 176 (4.68%) had the South Atlantic haplotype, and 3 individuals (0.08%) had the Gulf Coast haplotype. Detection of newly recruited oysters possessing the Gulf Coast haplotype in the Choptank River confirmed the survival and reproduction of the outplanted Louisiana oysters. If appropriate genetic tags are available, effective monitoring of stock-enhancement projects can be achieved with high-throughput molecular genotyping techniques.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by J.P. Grassle, New Brunswick 相似文献
994.
The photosynthesis–irradiance response of Ecklonia radiata (C. Agardh) J. Agardh, a common kelp in the temperate southern hemisphere, was investigated in situ throughout the year and across a depth profile at West Island, South Australia. Temperature and irradiance environment altered throughout the year, varying at 3 m between 14–20°C and 279–705 mol photons m–2 s–1. Photosynthetic capacity (Pm) varied throughout the year between 177–278 mol O2 g–1 dry wt h–1 at 3 m and 133–348 mol O2 g–1 dry wt h–1 at 10 m. The irradiance required for sub-saturation of photosynthesis (Ek) varied between 97–152 and 81–142 mol photons m–2 s–1 for 3 m and 10 m respectively, and the respiration rate varied between 15–36 and 13–20 mol O2 g–1 dry wt h–1 for 3 m and 10 m. A clear seasonal change in photokinetic parameters was detected and provided strong evidence for a seasonal acclimation response. During winter an increase in the efficiency of light utilisation at low irradiance () was accompanied by a decrease in both Ek and that required for photosynthetic compensation. Pm also increased during the winter and autumn months and respiratory requirements decreased. These changes enable E. radiata to display an optimal photosynthetic performance throughout the year despite significant changes in the surrounding environment.Communicated by P.W. Sammarco, Chauvin 相似文献
995.
S.?MoraisEmail author M.?Lacuisse L.?E.?C.?Concei??o M.?T.?Dinis I.?R?nnestad 《Marine Biology》2004,145(2):243-250
Ontogenetic changes in the capacity of Senegalese sole (Solea senegalensis Kaup, 1858) larvae to digest and metabolise Artemia protein and amino acids (AA) were studied using 12, 22 and 35 days after hatching (DAH) larvae that were fed Artemia metanauplii radiolabelled with a [U-14C] protein hydrolysate. About 82% and 18% of the label was incorporated into the Artemia trichloroacetic acid (TCA) precipitate (mostly protein) and soluble (mainly free AA) fractions, respectively. The digestibility of Artemia was high at all tested ages, with label absorption varying between 77% and 83% at 24 h after feeding (HAF). A rapid digestion, absorption and catabolism of Artemia AA were noted, with most of the absorption into the body occurring during the first 3 HAF. Traces of label were already found in the metabolic-CO2 trap at 1 HAF. Furthermore, label was largely and almost immediately incorporated into the TCA precipitate fraction (mostly protein) of gut and body tissues. Slight differences were noted in diet utilization between larvae at different ages. At 12 DAH larvae had a lower catabolism and evacuation of the label, as well as the highest accumulation in the gut. However, except for the amount of catabolised label, the results were not significantly different from those for 35 DAH larvae. Moreover, no significant differences were found in the amount of label incorporated into the body, although it seemed to be higher in 12 DAH larvae. Taken together, these results reveal a higher absorption and a significantly higher retention of the absorbed label in 12 DAH larvae. In addition, 12 DAH larvae appeared to have a slower absorption of the label, which, in continuously feeding larvae, might result in overall lower food absorption efficiency. Therefore, it seems that young larvae have the ability to compensate for a possible lower digestive capacity with higher body retention of absorbed AA. This study confirms that sole larvae, even young stages, have a high capacity for digesting live preys.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
996.
Sand shrimp, Crangon septemspinosa Say, are important to the trophic dynamics of coastal systems in the northwestern Atlantic. To evaluate predatory impacts of sand shrimp, daily energy requirements (J ind.–1 day–1) were calculated for this species from laboratory estimates of energy losses due to routine (RR), active (RA), and feeding (RSDA) oxygen consumption rates (J ind.–1 h–1), coupled with measurements of diel motile activity. Shrimp used in this study were collected biweekly from the Niantic River, Connecticut (41°33N; 72°19W) during late spring and summer of 2000 and 2001. The rates of shrimp energy loss due to RR and RA increased exponentially with increasing temperature, with the magnitude of increase greater between 6°C and 10°C (Q10=3.01) than between 10°C and 14°C (Q10=2.85). Rates of RR doubled with a twofold increase in shrimp mass, and RSDA was 0.130 J h–1+RR, irrespective of shrimp body size. Shrimp motile activity was significantly greater during dark periods relative to light periods, indicating nocturnal behavior. Nocturnal activity also increased significantly at higher temperatures, and at 20°C shifted from a unimodal to a bimodal pattern. Laboratory estimates of daily metabolic expenditures (1.7–307.4 J ind.–1 day–1 for 0.05 and 1.5 g wet weight shrimp, respectively, between 0°C and 20°C) were combined with results from previous investigations to construct a bioenergetic model and make inferences regarding the trophic positioning of C. septemspinosa. Bioenergetic model estimates indicated that juvenile and adult shrimp could meet daily energy demands via opportunistic omnivory, selectively preying upon items of high energy content (e.g. invertebrate and fish tissue) and compensating for limited prey availability by ingesting readily accessible lower energy food (e.g. detritus and plant material).Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by J.P. Grassle, New Brunswick 相似文献
997.
Intertidal organisms may employ circatidal rhythms to track the tidal cycle, but tidal patterns may vary within a species range and necessitate adaptation to the local tides. Circatidal rhythms were examined in populations of the eastern Pacific fiddler crab Uca princeps (Smith) from four sites with differing tidal characteristics, La Paz (24°10N; 110°21W), San Blas (21°33N; 105°18W) and Manzanillo (19°6N; 104°24W), Mexico (lower amplitude, mixed semidiurnal tides) and Mata de Limon, Costa Rica (9°55N; 84°43W) (high-amplitude, semidiurnal tides). Local tides were characterized by harmonic constants of M2, S2, K1, and O1, partial tides that largely determine their semidiurnal and diurnal features. Rhythmic structure in continuously recorded locomotor activity of individual crabs held under laboratory conditions was described by cosinor and periodogram methods of time-series analysis. Both daily and circatidal rhythms were found in crabs studied in light–dark cycles set to local conditions at the time of collection. Crabs at all four sites shared a tendency toward bimodality, with a mid-morning activity peak and varying degrees of nocturnal activity. Circatidal rhythms closely matching the period of the 12.42-h M2 partial tide were consistently present at all sites except Manzanillo. At Mata de Limon, the circatidal rhythm clearly dominated locomotor activity, but was strongly modulated by a daily rhythm in a repeating pattern at a semilunar interval. In contrast, the amplitude of the daily rhythm was higher than that of the circatidal rhythm in crabs from the three mixed tide sites on the Mexican coast, where the tidal pattern is dominated by a diurnal inequality arising from the diurnal K1 and O1 partial tides. These results suggest that populations of U. princeps use both daily and circatidal timing systems to track local forms of the tide generated by their M2, S2, K1, and O1 geophysical counterparts.Communicated by J.P. Grassle, New Brunswick 相似文献
998.
We demonstrated that environmentally relevant levels of UVA and UVB can reduce sperm motility (UVA: by 38–58%; UVB: by 42–85%; P < 0.05) and subsequently fertilisation success (UVA: by 38–72%; UVB: by 91–98%; P < 0.05) of urchins (Anthocidaris crassispina) in a dose-dependent manner, implicating that recruitment of urchin populations might be reduced by UVR (ultraviolet radiation) prevailing in their natural habitats. Concomitantly, reactive oxygen species (ROS) production was enhanced by UVA and UVB in a dose-dependent manner (UVA: by 1.3-fold; UVB: by 6.6–7.3-fold; P < 0.05), and the increase in ROS resulted in an increase in lipid peroxidation (LPO) in urchin sperm (UVA: by 4.2–7.2-fold; UVB: by 2.3–2.7-fold; P < 0.05). This study demonstrated that ROS production and oxidative damages enhanced by UVR may account for the observed declines in sperm motility and fertilisation, and suggests that levels of UVR prevailing in the environment may pose a significant threat to the reproductive success of natural populations of urchins spawning in shallow waters. 相似文献
999.
1000.