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111.
The grand skink, Oligosoma grande, is a diurnal rock-dwelling lizard from the tussock grasslands of Central Otago, New Zealand, whose diet includes a variety
of arthropods and fruit. We conducted a field experiment to examine the influence of prey distribution on foraging behavior
and spacing patterns. On sites where prey distribution was unaltered (control sites), males and females differed in diet and
foraging behavior. Most male feeding attempts were directed at large strong-flying insects, and males used a saltatory search
pattern that involved relatively infrequent moves of long duration. Females spent more effort catching small weak-flying insects
and visiting fruiting plants. Their search behavior involved frequent moves of short duration. The placement of meat-bait
on experimental sites led to a redistribution of large flies without influencing other prey types. Experimental females switched
foraging strategy by adopting a search pattern of relatively infrequent moves of long duration, increasing the frequency of
attempts to capture large prey, and reducing the importance of fruit in their diet. The experimental manipulation appeared
to influence space use. On control sites, both sexes had comparably sized home ranges. On experimental sites, male home ranges
were significantly larger than female home ranges.
Received: 3 November 1997 / Accepted after revision: 13 December 1998 相似文献
112.
Order and simplification are the first steps toward the mastery of a subject—the actual enemy is the unknown.
相似文献
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115.
Willow B. English Douglas Schamel Diane M. Tracy David F. Westneat David B. Lank 《Behavioral ecology and sociobiology》2014,68(12):1939-1949
Fisher’s sex ratio theory predicts that on average parents should allocate resources equally to the production of males and females. However, when the cost/benefit ratio for producing males versus females differs, the theory predicts that parents may bias production, typically through underproduction of the sex with greater variation in fitness. We tested theoretical predictions in the red-necked phalarope, a polyandrous shorebird with sex-role reversal. Since females are larger and therefore potentially more expensive to produce and may have greater variation in reproductive success, we predicted from Fisher’s hypothesis a male bias in population embryonic sex ratio, and from sex allocation theory, female biases in the clutches of females allocating more resources to reproduction. We measured eggs and chicks and sexed 535 offspring from 163 clutches laid over 6 years at two sites in Alaska. The embryonic sex ratio of 51.1 M:48.9 F did not vary from parity. Clutch sex ratio (% male) was positively correlated with clutch mean egg size, opposite to our prediction. Within clutches, however, egg size did not differ by sex. Male phalarope fitness may be more variable than previously thought, and/or differential investment in eggs may affect the within-sex fitness of males more than females. Eggs producing males were less dense than those producing females, possibly indicating they contained more yolk relative to albumen. Albumen contributes to chick structural size, while yolk supports survivorship after hatch. Sex-specific chick growth strategies may affect egg size and allocation patterns by female phalaropes and other birds. 相似文献
116.
Jennifer A. Hale Douglas A. Nelson Jacqueline K. Augustine 《Behavioral ecology and sociobiology》2014,68(9):1441-1449
Vocal signaling can be an important component of vertebrate communication during social interactions. If vocalizations vary among individuals but are consistent within a given individual, they may be used to discriminate among individuals. In many species, territorial males use vocalizations to discriminate between neighbors and strangers and either respond more aggressively toward strangers relative to neighbors (“dear enemy” effect) or they respond more aggressively toward neighbors relative to strangers (“nasty neighbor” effect). In the greater prairie-chicken (Tympanuchus cupido), male vocalizations are an integral part of the display males produce on leks. We investigated whether male greater prairie-chickens discriminate among familiar individuals on their own territory, familiar individuals outside their normal territory and strangers from a nearby lek. Vocal characteristics varied among males, suggesting that vocalizations may potentially be used by prairie-chickens to identify individuals. Males responded to playback of prairie-chicken calls by vocalizing at a faster rate and approaching the playback speaker, but did not vary in their response to the vocalizations based on the identity of the caller. Our results suggest that variation is present among the vocalizations of individual male greater prairie-chickens, but males do not appear to discriminate among familiar individuals and strangers based solely on their “boom” vocalizations. Greater prairie-chicken vocalization likely functions as a way of announcing that a territory is occupied and defended, but it may also serve as a way of advertising to conspecifics or as a signal that is secondary to other forms of communication. 相似文献
117.
Imitative song learning in birds often results in the formation of vocal dialects or local song neighborhoods in which males in close proximity share very similar songs. If song sharing confers a selective advantage due to intra-sexual competition or inter-sexual mate choice, song sharing should enhance the singer’s territory tenure or lifetime pairing success. We tested this in a migratory population of the Puget Sound white-crowned sparrow, Zonotrichia leucophrys pugetensis, in which some territory neighbors share whole songs. Song sharing with territory neighbors in the first year on territory did not correlate with territory tenure but correlated positively with social pairing success throughout a male’s lifetime when length of territory tenure was controlled. Thus, song sharing in this migratory population does not appear to confer a benefit in male–male interactions, at least as measured by the length of territory tenure. However, males that share songs do benefit from higher lifetime pairing success. Combined with the data available for other species, it appears that intra- and inter-sexual selection may have stronger effects on song sharing in sedentary and migratory populations, respectively. 相似文献
118.
Livestock populations in protected areas are viewed negatively because of their interaction with native ungulates through direct competition for food resources. However, livestock and native prey can also interact indirectly through their shared predator. Indirect interactions between two prey species occur when one prey modifies either the functional or numerical responses of a shared predator. This interaction is often manifested as negative effects (apparent competition) on one or both prey species through increased predation risk. But indirect interactions can also yield positive effects on a focal prey if the shared predator modifies its functional response toward increased consumption of an abundant and higher-quality alternative prey. Such a phenomenon between two prey species is underappreciated and overlooked in nature. Positive indirect effects can be expected to occur in livestock-dominated wildlife reserves containing large carnivores. We searched for such positive effects in Acacia-Zizhypus forests of India's Gir sanctuary where livestock (Bubalus bubalis and Bos indicus) and a coexisting native prey (chital deer, Axis axis) are consumed by Asiatic lions (Panthera leo persica). Chital vigilance was higher in areas with low livestock density than in areas with high livestock density. This positive indirect effect occurred because lion predation rates on livestock were twice as great where livestock were abundant than where livestock density was low. Positive indirect interactions mediated by shared predators may be more common than generally thought with rather major consequences for ecological understanding and conservation. We encourage further studies to understand outcomes of indirect interactions on long-term predator-prey dynamics in livestock-dominated protected areas. 相似文献
119.
Cnidarian–dinoflagellate symbioses are not well understood at the molecular level. Observed specificity between partners during
initiation, establishment, and maintenance of the relationship strongly implies a role for chemical signaling. This report
presents biochemical and immunocytochemical evidence for potential signaling molecules, as large molecular weight glycoproteins,
secreted by Symbiodinium dinoflagellates both in culture and in symbiosis. Polyclonal antibodies directed against recovered exudate from S. microadriaticum, the natural endosymbiont of Cassiopea xamachana, the upside–down jellyfish, were highly specific in recognizing exudates from Symbiodinium species that can successfully induce developmental metamorphosis in the host but did not recognize exudates from Symbiodinium species that do not. Immunoblot analyses showed S. microadriaticum exudate to be protease sensitive. Release of antigenic material by symbiotic S. microadriaticum was demonstrated through light and electron microscopy using immunogold-labeled anti-S. microadriaticum (anti-Sm-XuLg) antibodies as probes. These secreted, symbiont-derived glycoconjugates may be candidates for interspecific
molecular signals. 相似文献
120.
Michael A. Long Douglas L. Murray 《Journal of Agricultural and Environmental Ethics》2013,26(2):351-375
Ethical consumption is on the rise, however little is known about the degree and the implications of the sometime conflicting sets of values held by the broad category of consumers who report consuming ethically. This paper explores convergence and divergence of ethical consumption values through a study of organic, fair trade, and local food consumers in Colorado. Using survey and focus group results, we first examine demographic and attitudinal correlates of ethical consumption. We then report evidence that while many organic, fair trade, and local food consumers converge around similar values, some Colorado consumers support only local food, while opposing the consumption of organic and fair trade products. Next, we investigate how ethical consumers who converge and diverge frame their commitment to consuming ethically. The discussion and conclusion suggest that community development planners of projects that focus on ethical consumption will need to successfully traverse issues stemming from convergence and divergence to enjoy long-term sustained success. 相似文献