Predator-induced behavioral defense and its ecological consequences for two calanoid copepods

Summary We used an automated technique for the observation and quantification of zooplankton swimming behavior to study the behavioral responses of two congeneric, herbivorous, freshwater copepod prey to a copepod predator (Limnocalanus macrurus). One prey, Diaptomus sicilis, often co-occurs with Limnocalanus, while previous studies indicated that the zoogeographic distribution of the second prey, Diaptomus oregonensis, was independent of the predator. We found that in the presence of Limnocalanus, D. sicilis swims more slowly and with less hopping and jumping than D. oregonensis. Diaptomus sicilis is also attacked and consumed by the predator Limnocalanus macrurus less frequently than D. oregonensis. We suggest that the faster, noisier swimming of D. oregonensis increases its vulnerability to Limnocalanus. The behavioral defenses to both prey are induced by the presence of the predator, and may represent two different anti-predator strategies, crypsis and avoidance for D. sicilis and D. oregonensis respectively. In a zoogeographical analysis D. oregonensis occurs at densities below D. sicilis in lakes where Limnocalanus is at elevated abundances, while in low-predator lakes the opposite is true. This distribution pattern supports our experimental results, and suggests that D. sicilis is adapted to survive with Limnocalanus, while D. oregonensis is not.     

The reconciliation behavior of golden monkeys (Rhinopithecus roxellanae roxellanae) in small breeding groups

Observations were made following 130 spontaneous aggressive incidents in two small breeding groups of captive golden monkeys (Rhinopithecus roxellanae roxellanae). Participants were observed both during the first 10 min following these incidents and during matched control observations. An increased contact rate was observed between opponents following the aggressive incident. Post-conflict contacts were characterized by a number of behavior patterns: open mouth, rapid grooming, embrace, and crouching. Adult males played an important role as mediator in agonistic disputes among females: males intervened in 93.6% of female fights. It is speculated that this intervention behavior is related to the species' organization into one-male units.     

Auditory assessment of avian predator threat in semi-captive ringtailed lemurs (Lemur catta)

Antiraptor responses from forest-living ringtailed lemurs to advertisement calls of naturally-occurring red-tailed hawks suggested that the lemurs discriminated these calls from other environmental sounds. A series of playback experiments, using real animal sounds and synthetic sound probes, was conducted to investigate the acoustic basis of this putative discrimination. Two semi-captive groups of ringtails served as study subjects: one group had many years of experience living in the forest, whereas the other group had relatively little such experience. Responses to playbacks suggested that both groups used the same acoustic criteria to discriminate “calls of large hawks” from other sounds, but the range of auditory stimuli that evoked antiraptor responses was broader for the experienced group than for the inexperienced group. Although several interpretations of the experimental results are possible, one that seems particularly compatible with the data is the “prototype” concept of stimulus categorization.     

Restoration of normal stamen development and pollen formation by fusion of different cytoplasmic male-sterile cultivars of Nicotiana tabacum

Summary Fusion of two cytoplasmic male-sterile cultivars of Nicotiana tabacum, one with N. bigelovii cytoplasm and one with N. undulata cytoplasm, resulted in the restoration of male fertility in cybrid plants. All male-fertile cybrids exhibited fused corollas, which is characteristic for the cultivar with N. undulata cytoplasm, while their stamen structures varied from cybrid to cybrid, some producing stamens with anthers fused to petal-like appendages and one producing stamens of a normal appearance for N. tabacum. Restriction enzyme digestion and agarose gel electrophoresis of mitochondrial DNA showed that mitochondrial DNA of the fertile cybrids was more similar to the male-sterile cultivar with the cytoplasm of N. undulata than to the cultivar with N. bigelovii cytoplasm. Some restriction fragments were unique to the male-fertile cybrids. Comparisons between stamen structure and mitochondrial DNA for eight fertile progeny from one cybrid plant led to the identification of several restriction fragments that appeared at enhanced levels in connection with normal stamen development.     

Structural studies of microsporogenesis in fertile and male-sterile onions (Allium cepa L.) containing the cms-S cytoplasm

Summary The structure of anther tissues has been studied during microsporogenesis in male-sterile and -fertile onions. Three types of abnormal tapetal behaviour have been observed within the single line II/3ms containing the cms-S cytoplasm: type 1, the premature breakdown of the tapetum at the tetrad stage, type 2, the hypertrophy of the tapetum after the diad stage followed by its premature autolysis and, type 3, in which the tapetum remains in good condition but for an abnormally long period of time. Tapetal autolysis proceeds in the same manner in both male-steriles and -fertiles with only the stage at which it occurs differing between the types of plants. Mitochondria were prominent in the tapetal tissue of all onion types throughout all stages of microsporogenesis and were still visible during the last stages of tapetal autolysis. In a detailed study of type 2 behaviour, no differences in mitochondrial volumes were found until the tapetum hypertrophied.     

Male sterility and restored fertility in annual mercuries, relations with sex differentiation

The paper summarizes the researches conducted on male sterility in Mercurialis annua. Totally sterile individuals are very scarce in the dioecious species showing as the other Mercuries, unisexual flowers devoid of rudiments of the opposite sex. From one sterile male mutant, a ‘sterile series’ was conducted and genetics was studied. Sterile, semisterile, restored fertile male lines were constructed as well as female lines containing the inducer gene of male sterility, both fertility restorers and the sensitive cytoplasm. Morphology and ontogeny of these isogenic lines were presented. Male sterile anthers (empty) present a splitted tapetum and an abnormal meiotic end. Restored fertile male lines were normal. The relative abundance of auxin and cytokinins was studied. A specific cytokinin pathway measured as a background in fertile lines, the cis-oxidized pathway characterised the ‘sterile series’. Restoration of normal meiosis and tapetum appeared for the highest quantities of cis-zeatin (669 ng instead of 192 ng/100 g fresh weight in totally sterile). Auxin quantities were abundant compared with the normal males. Gene expression in the ‘sterile series’ was also compared with the fertile lines. t-RNAs specific for normal females were expressed in the male ‘sterile series’. Hybridization kinetics and in vitro translations pf poly(A)⁺RNAs demonstrate specific sequences for each line. Comparisons between identical organs (normal fertile male/restored fertile male or normal female/female of the ‘sterile series’) exhibited nearly 10% differences. The results suggest that for stamen development, a cascade of regulators probably exists: sex genes acting on the induction of stamen or pistil, then genes for sterility/restoration of fertility acting in anthers. Fertility-sterility regulators control the synthesis of a specific cytokinin pathway. The new hormonal signals are linked to several specific genes expressed in the floral morphology characterizing each line of the ‘sterile series’.     

雄性生殖单位研究的回顾和展望

本文扼要回顾和评述了雄性生殖单位的发现、意义和研究进展,并对目前存在的问题和今后的研究进行了讨论和展望。     

欺骗,契约,合作的ESS

动物竞争中的欺骗、契约、合作现象是极为常见的。本文就论述与此有关的ESS。一、欺骗某些动物竞争时信号a后跟随发生行为A,如一个体不出现A则为欺骗。欺骗是相对真实     

Effects of selective cholecystokinin antagonists L364,718 and L365,260 on food intake in rats

The selective type A and B cholecystokinin (CCK) receptor antagonists L364,718 and L365,260 were used to identify the receptor subtype that mediates the satiety effect of endogenous CCK. Male rats (n = 12–13/group), fed ground rat chow ad lib, received L364,718 (0, 1, 10, 100, or 1000 μg/kg IP) or L365,260 (0, 0.1, 1, 10, 100, 1000, or 10,000 μg/kg IP) 2 h after lights off, and food intake was measured 1.5, 3.5, and 5.5 h later. L364,718 significantly stimulated 1.5-h food intake by more than 40% at 10 μg/kg and higher doses; cumulative intake at 3.5 and 5.5 h remained elevated by about 20% at 1000 and 100 μg/kg of L364,718, respectively. In contrast, L365,260 had no significant stimulatory effect on feeding at any dose. The potency of L365,260 for antagonizing gastrin-stimulated gastric acid secretion was examined in unanesthetized rats. Male rats (n = 14), prepared with gastric and jugular vein cannulas, received doubling doses of gastrin (G-17I) (0.16–5 nmol/kg/h IV), each dose for 30 min, and gastric juice was collected for each 30-min period. G-17I stimulated gastric acid output dose dependently; the minimal effective dose was 0.16 nmol/kg/h, while maximal output (5-fold above basal) occurred at 5 nmol/kg/h. L365,260 (0, 1, 10, 100, 1000, or 10,000 μg/kg IV), administered 30 min before continuous infusion of G-17I (1.25 or 5 nmol/kg/h), significantly inhibited acid output only at 10,000 μg/kg; cumulative 60-min output was decreased by 60%. These results suggest that CCK acts at CCK-A receptors to produce satiety during the dark period in ad lib-feeding rats.