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1.
Baboon sexual swellings: information content of size and color   总被引:1,自引:0,他引:1  
Primate sexual swellings are hormone-dependent sexual signals that play a key role in determining patterns of behavior. They are among the most conspicuous signals exhibited by any mammal, and their large size and bright coloration have fascinated evolutionary biologists for well over a century. A number of different adaptive hypotheses have been proposed for the evolution of sexual swellings, and there have been several recent attempts to test some of these using precise swelling measurements made in the field. Most of these studies have focused only on the size element of the swelling, and those that have measured other aspects of swellings, such as color, have done so only crudely. A focus solely on swelling size is inconsistent with most theoretical models of mate choice, which emphasize the importance of multiple cues within sexual signals. Here, we present data on baboon (Papio hamadryas anubis) sexual swellings, including measures of both swelling size and color, measured objectively using digital photography at Gashaka-Gumti National Park, Nigeria. We combined these measurements with detailed data on fecal progestogen and estrogen levels, and estimates of the timing of ovulation and the fertile period around ovulation based on those levels. We show that swelling color and size vary independently, and that, consistent with results in other species, swelling size contains information about the timing of ovulation and the fertile period. However, we show that swelling color does not contain such information. In addition, swelling size contains information about female parity, and we found some evidence to suggest that color may also contain such information. These results indicate that baboon sexual swellings may contain information about multiple aspects of female fertility. We discuss the implications of these results for understanding the nature of swellings as behavioral signals, and the role of swellings in mate choice.  相似文献   
2.
We investigated relationships between fecal androgen concentrations, facial coloration and behaviour in semi-free-ranging male mandrills. We found that fecal androgen levels were significantly positively related to dominance rank, independent of rank stability and the mating period, suggesting that male mandrills live in a permanently aggressive context in which they must actively maintain their dominance status. Facial red coloration was also significantly related to both fecal androgen levels and rank, with high ranking males having both higher androgen levels and redder faces, although dominant males did not always have the highest androgen levels or the reddest faces. Predictive relationships between androgen levels, coloration and rank were short-term. Androgen concentrations and facial redness both increased in the presence of receptive females, as did the former during periods of rank instability. We conclude that male facial redness is likely to represent an honest signal (to other males) of current androgen status, competitive ability and willingness to engage in fights and that females may also use this to assess male condition. Further, our findings provide support for the “challenge hypothesis” as originally proposed for birds by Wingfield.  相似文献   
3.
Synopsis An annual spawning aggregation of Nassau grouper,Epinephelus striatus, observed off the southern coast of Quintana Roo, Mexico, on full moon days in December and January, was surveyed during the winters from 1991 to 1993. A fish aggregation had been appearing at one traditional site off Mahahual for more than 80 years, but currently it forms at undetermined sites far from the original site. Fish migration was northwards in the fore reef border along the 14 m isobath and isolated groups were observed. Through visual assessment fish aggregations were found to include 200 to 500 individuals. The fishing on Nassau grouper aggregations has been active since 1910 by using hook and line; however, recently fishermen used gill nets. It is necessary to continue the research on this aggregation and establish management guidelines to protect the species.  相似文献   
4.
采用在基础饲料中分别添加0、130和260 mg/kg的合成虾青素配制成3种粗蛋白和粗脂肪含量分别为42%和16%的等氮等脂的中华绒螯蟹(Eriocheir sinensis)育肥饲料(分别记为饲料1、2和3), 以中华绒螯蟹商业育肥饲料作为饲料4, 分别投喂4组雌蟹(每个饲料组3个重复水槽, 每个水槽中12只蟹), 进行为期60d的室内养殖实验, 以探讨添加合成虾青素对中华绒螯蟹成体雌蟹性腺发育、色泽及抗氧化能力的影响。结果显示: (1)实验进行到30d和60d, 在饲料中添加虾青素对雌体肝胰腺指数(HSI)和性腺指数(GSI)均无显著影响(P>0.05)。(2)性腺、肝胰腺和头胸甲中的总类胡萝卜素含量和红度值(a值)均以饲料3组最高, 性腺亮度值(L值)和黄度值(b值)以饲料1组最高(P<0.05); 饲料2组头胸甲的b值最高, 饲料1组最低(P<0.05)。(3) 饲料1组中华绒螯蟹血清过氧化物酶(POD)活性显著高于其他组, 饲料4组的过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)、乳酸脱氢酶(LDH)、总抗氧化能力(T-AOC)、丙二醛(MDA)和乳酸(LD)含量最高(P<0.05); 肝胰腺中的SOD、T-AOC、GSH-Px和GR活性均以饲料1组最高, 饲料2组最低(P<0.05)。(4) 饲料2组血清酸性磷酸酶(ACP)活性和血蓝蛋白(Hc)含量显著高于其他组, 其余各组间差异不显著。血清中的碱性磷酸酶(ALP)和γ-谷氨酰转移酶(γ-GT)活性和一氧化氮(NO)含量均以饲料4组最高(P<0.05), 肝胰腺中的ACP、ALP和γ-GT活性以饲料1组最高。综上, 在育肥饲料中添加合成虾青素对成体雌蟹性腺发育无显著影响, 但可显著提高头胸甲、肝胰腺和卵巢中的类胡萝卜素总量、色泽和抗氧化能力, 建议雌蟹育肥饲料中合成虾青素的含量为90 mg/kg左右。  相似文献   
5.
Synopsis In Venezuela, guppies,Poecilia reticulata, are found in a diversity of aquatic ecosystems fringing the western slope of the eastern Andes. These inland drainages are associated with large between-site variation in both physical and biotic environments. Numbers of potential guppy predators vary greatly between low diversity piedmont streams and high diversity llanos swamps. We analyze geographic variation in several phenotypic traits associated with conspicuousness of male guppies as an independent test of Haskins' (Haskins et al. 1961) hypothesis of natural balance between sexual selection (driving male conspicuousness) and predation (driving crypsis). Four sites were compared: a diverse llanos swamp (high predation), two Andean piedmont streams (intermediate and low predation), and a spring pool located south of Venezuela's Paría Peninsula (no aquatic predators). Because tropical wet and dry seasons are associated with varying degrees of environmental change at these sites, within-site seasonal samples provided an additional test of the role of selective predation on Male phenotypes. Phenotypic traits associated with both size and coloration supported the sexual selection/predation hypothesis. male guppies from the spring were generally more colorful than male guppies from inland drainages. Males from the diverse swamp site were smaller and less colorful than guppies from other sites. Males from the swamp population were smallest and least colorful during the early dry season, when diurnal aquatic piscivores were more diverse and abundant. Dominant spot pigments at each site were generally those that provided greatest contrast with the predominant environmental background color, lending further evidence that coloration patterns in male guppies enhance conspicuousness.  相似文献   
6.
Female ornaments in animals with conventional sex roles have traditionally been considered non-functional, being merely a genetically correlated response to selection for male ornamentation. Alternatively, female ornaments may be influenced by selection acting directly on the females, either through female–female competition or male choice. We tested the latter hypothesis in mate choice experiments with bluethroats (Luscinia s. svecica), a passerine bird in which females vary considerably in coloration of an ornamental throat patch. In outdoor aviaries placed in prime breeding habitat, males were allowed to choose between a colourful and a drab female. We found that males associated more with, and performed more sexual behaviours towards, colourful females. Female coloration was not age-related, but correlated significantly with body mass and tarsus length. Thus, we have demonstrated both a male preference for female ornamentation, and a relationship between ornament expression and female body size, which may be indicative of quality. Our results refute the correlated response hypothesis and support the hypothesis that female ornamentation is sexually selected.  相似文献   
7.
Synopsis The behavior and ecology of the firemouth cichlid were investigated in southern Mexico. Observations were conducted primarily at Laguna Bacalar, Quintana Roo. The fish bred throughout the year, nesting in small rocky crevices. Territories were established either by wandering pairs or by lone males which subsequently attracted mates. Stationary territories were maintained for two to three weeks by both pair members until the young were free-swimming, after which the parents defended the young as they foraged. Brood care lasted approximately three months. The distances at which fish were attacked and the behavior performed varied with the age of the defended young and the sex of the parent, as well as the species and size of the intruder. The sexes differed in their reproductive and agonistic activities. Predation on young was rapid if the parents were diverted from their defense. Serious injuries to adults were not observed to result from intraspecific contests. Such interactions were very common, but were ritualized with physical contact between animals rare. Color patterning varied with breeding interval, sex and behavior.  相似文献   
8.
The occurrence of coral snake coloration among unrelated venomous and non-venomous New World snake species has often been explained in terms of warning coloration and mimicry. The idea that snake predators would avoid coral snakes in nature seems widely established and is postulated in many discussions on coral snake mimicry. However, the few workers that have tested a potential aposematic function of the conspicuous colour pattern focused exclusively on behaviour of snake predators towards coloured abstract models. Here we report on behaviour of temporarily caged, wild coatis (Nasua narica) when confronted with co-occurring live snakes, among which were two species of venomous coral snakes. Five different types of responses have been observed, ranging from avoidance to predation, yet none of the coatis avoided either of the two coral snake species or other species resembling these. As in earlier studies coatis appeared to avoid coral snake models, our findings show that results from studies with abstract snake models cannot unconditionally serve as evidence for an aposematic function of coral snake coloration.  相似文献   
9.
Synopsis Creediid fishes usually live burrowed in sand. When disturbed they make quick movements out and back into the sand. The darting behavior of 35 individualLimnichthys nitidus was recorded on videotape with the aid of SCUBA in the shallow bay, Marsa Muqabelah, Egypt, on the NE coast of Sinai in the Gulf of Aqaba, Red Sea. Thirty-nine sequences show that these fish travel distances of 26.7 to 110 mm in a single dart (1.7 to 5.5 times their total length), can reach speeds of nearly 0.5 m per sec, and execute turns up to 185° to avoid objects in their path. The darting movements, size and cryptic coloration ofL. nitidus make them difficult to see yet they may be the most numerous fish in shallow sandy areas of the Red Sea reaching concentrations of over 50 m-2, a density exceeded in chordates only by the lancelet,Branchiostoma caribaeum. Their population in Marsa Muqabelah was drastically reduced, along with that of other sand fishes, between 1987 and 1989 when the sand became mostly covered with an overgrowth of algal mats and sea grasses.  相似文献   
10.
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