Search Results
Results 451 - 500 of 905
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Royle Nick J - - 2005
Whilst there is an abundance of studies revealing how dominance interactions affect access to resources critical for survival and reproductive success, very little is known about how dominance status is influenced by early life experiences. However, there is increasing evidence that early developmental trajectories can shape the physiology and behaviour ...
Aday D Derek - - 2006
The ultimate body size that an individual fish achieves can be a function both of direct effects of growth or indirect effects associated with the timing of sexual maturation (and associated energetic tradeoffs). These alternatives are often invoked to explain variation in body size within and among fish populations, but ...
Anderson Dean P - - 2006
Although the energetics of the estrous cycle in primates is not well understood, evidence suggests that energy and nutrient acquisition influence ovulation and the timing of conception. Energy for estrus has to compete with energy allocated for cellular maintenance, thermoregulation, movement for food, and predation avoidance. While some chimpanzee (Pan ...
Heike Pröhl
One or both sexes exhibit territorial behavior in all dendrobatids that have been studied. Two types of territoriality are identified. In some Colosthethus species only females or both sexes defend small nonreproductive territories that offer access to water, food, and shelter. In other species, only males defend large reproductive territories ...
ALEJANDRO SALINAS-MELGOZA
We used radio-telemetry techniques to determine hourly activity patterns of 29 juvenile Lilac-crowned Parrots (Amazona finschi) during 1996–2000 in tropical dry forest of Jalisco, Mexico. Parrots had two peak activity periods—early morning and late afternoon—for both overall activity and local movement. Individuals were generally inactive and did not change location ...
Siefferman Lynn - - 2005
Although the function of ornamental traits in males has been the focus of intensive research for decades, expression of such traits in females has received much less study. Eastern bluebirds (Sialia sialis) display structurally based ultraviolet/blue and melanin-based chestnut plumage, and in males this plumage coloration is related to both ...
Tarasuk Valerie - - 2005
This study was undertaken to characterize nutritional vulnerability among a sample of homeless youth in downtown Toronto. Interviews were conducted with 261 homeless youth (149 male, 112 female), recruited from drop-in centers and outdoor locations. Information about current living circumstances, nutrition and health-related behaviors, and 24-h dietary intake recalls were ...
Parisot Maëlle - - 2005
The challenge hypothesis predicts that plasma testosterone (T) concentration is high when male-male competitions are high and decreases when males are engaged in paternal care. In monogamous species, T concentration increases at the beginning of the breeding period and decreases after egg laying. According to the challenge hypothesis, increasing competition ...
Prendergast Brian J - - 2005
Orientation of physiology and behavior in time is a major adaptation common to many organisms and represents a significant challenge. In the face of predictable seasonal changes in climatic factors, and as a result of natural selection, many mammals now restrict their reproductive efforts to the fraction of the year ...
Lindgren B - - 2005
In ectothermic organisms, declining season length and lower temperature towards higher latitudes often select for latitudinal variation in growth and development. However, the energetic mechanisms underlying this adaptive variation are largely unknown. We investigated growth, food intake and growth efficiency of Rana temporaria tadpoles from eight populations along a 1500 ...
Wilder Shawn M - - 2005
While many species show positive relationships between population density and habitat patch area, some species consistently show higher densities in smaller patches. Few studies have examined mechanisms that may cause species to have negative density-area relationships. We tested the hypothesis that greater reproduction in edge versus interior habitats and small ...
Merrill Ray M - - 2005
OBJECTIVE: To identify the influence season and climate have on physical activity among US adults. METHODS: Seven weather classifications from 255 weather stations were linked with 355 counties covered by the 2003 BRFSS. RESULTS: The percentage meeting the recommendations for physical activity ranged from 30.9% in Puerto Rico to 60.9% ...
Al-Almaie Sameeh - - 2005
BACKGROUND: Bad dietary habits, such as eating high-fat/high-energy food, can contribute to obesity in adolescents, which tends to persist into adulthood. The objective of this study was to determine the level and sources of knowledge about foods and healthy diets among male and female adolescents. METHODS: This was a cross-sectional ...
Davis Caroline - - 2005
The characteristic symptoms of SAD, including hypersomnia and weight gain, might reflect a genetically programmed attempt to conserve energy during historically predictable periods of dwindling food supply. While this basic hypothesis has obvious conceptual appeal, few authors have considered the specific positive selection pressures that might have contributed to such ...
Li Zhaoyuan - - 2005
The socioecology of white-headed langurs (Trachypithecus leucocephalus) was studied in Fusui Precious Animal Reserve, Guangxi, China, in 1997/1998. Habitat quality was classified according to the level of human disturbance. Plant species diversity increased with habitat quality. Important foods for the langurs occurred more in high-quality habitat. Home range size varied ...
Valić, D.
Musky octopus, Eledone moschata is widespread in the Mediterranean on various bottom types. Although it is common in fishery landings its ecology is still poorly known. The life span of this species is up to two years. Females can spawn in wide period, ranging from couple of days to few ...
Fox, A.D.
Intensification of agriculture since the 1950s has enhanced the availability, competitive ability, crude protein content, digestibility and extended growing seasons of forage grasses. Spilled cereal grain also provides a rich food source in autumn and in winter. Long-distance migratory herbivorous geese have rapidly exploited these feeding opportunities and most species ...
Gore J Chad - - 2005
The German cockroach, Blattella germanica (Linnaeus) (Dictyoptera: Blattellidae), produces several potent human allergens, one of which, Blattella germanica allergen 1 (Bla g 1), is produced in the midgut and excreted in faeces. We tested with descriptive and experimental approaches the hypothesis that Bla g 1 production is related to food ...
Tracy Christopher R - - 2005
We examined the effects of hibernation and fasting on intestinal glucose and proline uptake rates of chuckwallas (Sauromalus obesus) and on the size of organs directly or indirectly related to digestion. These lizards show geographic variation in body size and growth rate that parallels an elevational gradient in our study ...
Zykov Victor - - 2005
Self-reproduction is central to biological life for long-term sustainability and evolutionary adaptation. Although these traits would also be desirable in many engineered systems, the principles of self-reproduction have not been exploited in machine design. Here we create simple machines that act as autonomous modular robots and are capable of physical ...
Taylor Emily N - - 2005
Food availability is an important factor in the life histories of organisms because it is often limiting and thus can affect growth, mass change, reproduction, and behaviors such as thermoregulation, locomotion, and mating. Experimental studies in natural settings allow researchers to examine the effects of food on these parameters while ...
Weatherhead Patrick J - - 2005
Predicting ecological consequences of climate change will be improved by understanding how species are affected by contemporary climate variation, particularly if analyses involve more than single ecological variables and focus on large-scale climate phenomena. I used 18 years of data from red-winged blackbirds (Agelaius phoeniceus) studied over a 25-year period ...
Polishchuk Leonard V - - 2005
The concept of body mass dynamics can be viewed as part of life history theory, but its potential has remained largely untapped due to a lack of analytical methodology. We therefore propose a method, called contribution analysis, which enables us to decompose a change in body mass into contributions associated ...
Soini Helena A - - 2005
Stir bar sorptive extraction method was used for investigation of the urinary volatile profiles in male and female Phodopus campbelli and Phodopus sungorus hamsters. Additionally, female Phodopus roborowsky urinary profiles were characterized. A quantitative analytical approach allowed comparisons of 17 selected compounds in urine. Results showed that campbelli and sungorus ...
Vasey Natalie - - 2005
The activity budgets and daily activity rhythms of Varecia rubra were examined over an annual cycle according to season and reproductive stage. Given the relatively high reproductive costs and patchy food resources of this species, I predicted that V. rubra would 1) travel less and feed more during seasonal resource ...
Overdorff Deborah J - - 2005
Although many Malagasy lemurs are thought to be female dominant and to have female feeding priority, to date the relationship between these behaviors has been rigorously established only in Lemur catta, and other ways that females might achieve feeding priority have not been examined closely. Erhart and Overdorff [International Journal ...
Benson, John Farnum
Louisiana black bears (Ursus americanus luteolus) exist in 3 isolated populations in Louisiana and are listed as a threatened subspecies under the United States endangered species act. In order to establish a population of black bears in central Louisiana and to promote connectivity among existing populations 11 adult females and ...
Ferretti Valentina - - 2005
Since David Lack first proposed that birds rear as many young as they can nourish, food limitation has been accepted as the primary explanation for variation in clutch size and other life-history traits in birds. The importance of food limitation in life-history variation, however, was recently questioned on theoretical grounds. ...
KERRY L. GRIFFIS-KYLE
Aspen stands and riparian areas are important to breeding birds in the southwestern U.S. because they provide resources such as food and shelter. We investigated how this importance varies throughout the year for both resident and migratory birds. We sampled birds in 96 sites, half in small isolated aspen stands ...
Garidou-Boof Marie-Laure - - 2005
Like nocturnal rodents, the diurnal tropical rodent Arvicanthis ansorgei shows a daily rhythm in pineal melatonin content. Seasonal and photoperiodic variations in the biosynthetic activity of the pineal gland: arylalkylamine-N-acetyltransferase (AA-NAT), hydroxyindole-O-methyltransferase (HIOMT) activities and melatonin content were measured in male and female A. ansorgei captured near Samaya, Mali, and ...
Grant Peter R - - 2005
Periodical cicadas in the genus Magicicada have unusually long life cycles for insects, with periodicities of either 13 or 17 years. Biologists have explained the evolution of these prime number period lengths in terms of resource limitation, enemy avoidance, hybridization and climate change. Here, I question two aspects of these ...
Vescio Theresa K - - 2005
This work tested the following hypothesis: When powerful men stereotype their female subordinates in masculine domains, they behave in patronizing ways that affect the performance of their subordinates. Experiment 1 examined the stereotyping tendencies and patronizing behaviors of the powerful. Findings revealed that powerful men who stereotyped their female subordinates ...
M. D. Subida
We quantified abundance and biomass of the amphipod Gammarus chevreuxi Sexton from benthic cores, sampled monthly over 1 y in the upper reaches of Canal de Mira, the southern arm of the Ria de Aveiro, Portugal. Abundance and biomass showed no clear seasonal patterns but were associated with variation in ...
Schärer L - - 2005
Sex allocation theory for simultaneous hermaphrodites assumes a direct trade-off between the allocation of resources to the male and female reproductive functions. Empirical support for this basic assumption is scarce, possibly because studies rarely control for variation in individual reproductive resource budgets. Such variation, which can have environmental or genetic ...
Lepage, Denis; DST Centre ...
The question of how aridity might influence avian clutch size, through the influences of rainfall seasonality and environmental stochasticity (unpredictability), has received little attention. A marked east-west gradient in aridity across South Africa provides a unique opportunity to test for such influences. Using an extensive collection of nest records for ...
Tatarenkov A - - 2005
Reproduction of attached large brown algae is known to occur only by sexual zygotes. Using microsatellites we show evolution of asexual reproduction in the bladder wrack promoting population persistence in the brackish water Baltic Sea (< 6 psu). Here a dwarf morph of Fucus vesiculosus is dominated by a single ...
Cavallini M M - - 2005
The concept of ecological niche, considered by the food dimension point of view, was used to characterize a small farmers community from the south of Minas Gerais State (Brazil). Ten small farmer families and 76 different meals eaten by them were evaluated in this study, during three different periods: September ...
Heukelbach Jörg - - 2005
Tungiasis (caused by the sand flea Tunga penetrans) is hyperendemic in many resource-poor communities in Brazil. To understand transmission dynamics of this parasitic skin disease in a typical endemic area, a longitudinal study was carried out in a slum in Fortaleza in northeastern Brazil. In a door-to-door survey, the population ...
Bicca-Marques Júlio César - - 2005
Birth seasonality in wild neotropical primates has been suggested to increase with latitude as a response to a stronger divergence in high-quality food availability across the year, and a higher between-year predictability at higher latitudes related to temporal differences in photoperiod. In captivity, however, monkeys are fed foods of similar ...
Willis M A - - 2005
The location of distant resources using odor information usually also requires information on the flow of air (or water) through the environment together with the expression of internally programmed steering responses. The orientation responses of virgin male Periplaneta americana L. to wind and the female sex-pheromone component (-)-periplanone-B were video-recorded ...
Zelleke G - - 2005
(1) Four breeding groups of Rhode Island Red and White Leghorn domestic fowl (RIR (female) x RIR (male), RIR (female) x WL (male), WL (female) x RIR (male) and WL (female) x WL (male)) were compared for fertility, hatchability, and their post-insemination sustainability, egg weight loss during incubation and uncovered ...
Dahlin C R - - 2005
Pinyon jays (Gymnorhinus cyanocephalus) have a complex social system that may require a complex communication system. They need to interact with multiple flock members, and they form life-long pair-bonds. We researched whether pinyon jays would selectively vocalize depending on the presence or absence of food and certain flock members. We ...
Boivin Guy - - 2005
Reproduction is a major life-history trait but it has been studied mostly in relation to female reproductive effort. Recently, an ovigeny index using the proportion of oocytes ready to be oviposited at eclosion has been proposed for female insect parasitoids. Here, we propose a spermatogeny index for male parasitoid wasps. ...
Stauffer, Donald J; 1Center ...
The reproductive biology of two species of Africanhornbill, the Black-casqued Hornbill, <i>Ceratogymna</i><i> atrata</i>, and the White-thighed Hornbill,<i> Ceratogymna cylindricus</i>, was investigated over a four-year period (1994–1997) on a 25km<sup>2</sup> site in lowland rainforest in south-central Cameroon. Nesting attempts varied considerably among years, with the percentage of successful nests highest in ...
Lebas Natasha R - - 2005
Nuptial gifts are food items or inedible tokens that are transferred to females during courtship or copulation . Tokens are of no direct value to females, and it is unknown why females require such worthless gifts as a precondition of mating. One hypothesis is that token giving arose in species ...
Both, Christiaan
Climate change has advanced the breeding dates of many bird species, but for few species we know whether this advancement is sufficient to track the advancement of the underlying levels of the food chain. For the long-distance migratory pied flycatcher Ficedula hypoleuca the advancement in breeding time has been insufficient ...
Visser, Marcel E.
Climate change is apparent as an advancement of spring phenology. However, there is no a priori reason to expect that all components of food chains will shift their phenology at the same rate. This differential shift will lead to mistimed reproduction in many species, including seasonally breeding birds. We argue ...
Stephen Beatty
By examining Western Australian freshwater crayfishes, this thesis aims to further our understanding of how life-history strategies, trophic relationships and disease introductions contribute to the threats posed by introduced species. Reproductive and population biology of two species of freshwater crayfish endemic to Western Australia (the marron Cherax cainii and gilgie ...
Ottosson, Ulf
The Garden Warbler is a classic subject for the study of Palaearctic-African bird migration strategies. Most studies have considered the situation close to the breeding areas, while the African and especially the sub-Saharan part of the species' migration have received comparatively little attention. Here we use autumn and spring ringing ...
Fan Y - - 2005
The German cockroach, Blattella germanica (L.), produces several potent protein aeroallergens, including Bla g 4, a approximately 20 kDa lipocalin. RT-PCR, Northern analyses and in situ hybridization showed that Bla g 4 is expressed only in the adult male reproductive system. Western blotting and ELISA with rBla g 4 antiserum ...
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