Density-dependent plasticity of sequential mate choice in a bushcricket (Orthoptera:Tettigoniidae)

2007 ◽  
Vol 55 (2) ◽  
pp. 123 ◽  
Author(s):  
Gerlind U. C. Lehmann
Keyword(s):  
Population Density ◽  
Mate Choice ◽  
High Density ◽  
High Population Density ◽  
Mating Period ◽  
Search Behaviour ◽  
Accessory Glands ◽  
Sequential Mate Choice ◽  
Mate Sampling ◽  
Copulation Attempt

Mate choice is a common phenomenon in animals and several factors have been proposed as being involved in the acceptance or rejection of a partner. I investigated the effect of population density on the mate-sampling behaviour of female Xederra charactus (bushcrickets). In my study, female bushcrickets adjusted the tactic of sequential mate sampling in response to mate density, visiting a series of up to five different males per night. Under low-density conditions, females visited fewer males in a night and were less likely to reject a copulation attempt than females under high-density conditions. Rejection of a male occurred during 29% of copulations in areas of high population density, but during only 8% in areas of low population density. Moreover, at low densities, females were less likely to reject mates later in the night, which can be interpreted as a reaction to the time constraints of a finite nightly mating period. Females in high-density populations also more often chose males with a higher mass of the spermatophore-producing accessory glands. Due to such choice, females might receive a larger nuptial gift at mating. These results are consistent with tactical models of search behaviour in which females adjust their behaviour to the number of potential mates and the length of the mating period.

Community based design approach as initial stage to promote urban composting from a Hill Station of the Philippines

2019 ◽  
Author(s):  
Marcelino Jr Lunag ◽  
Jessie C. Elauria ◽  
Juanito D. Burguillos
Keyword(s):  
Population Density ◽  
Community Involvement ◽  
The Philippines ◽  
Design Stage ◽  
High Population Density ◽  
Community Based ◽  
Hill Station ◽  
Initial Stage ◽  
Household Members ◽  
Community Based Design

This study confirms that lack of space due to high population density restricts household members and the barangay to comply with the existing law regarding composting. With these, community involvement in the design stage of compost bin as initial stage was done accordingly. The participants were voluntarily interviewed and were given questionnaires, which was endorsed and approved by barangay committee.

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

scholarly journals An experimental assessment of social tolerance and den ecology in a high-density octopus population

2021 ◽  
Vol 168 (5) ◽  
Author(s):  
Duncan A. O’Brien ◽  
Michelle L. Taylor ◽  
Heather D. Masonjones ◽  
Philipp H. Boersch-Supan ◽  
Owen R. O’Shea
Keyword(s):  
Deep Sea ◽  
Marine Species ◽  
High Density ◽  
Behavioural Plasticity ◽  
High Population Density ◽  
Social Tolerance ◽  
Potential Prey ◽  
The Bahamas ◽  
The Social ◽  
Den Use

AbstractLong held notions of the universally asocial octopus are being challenged due to the identification of high-density and interacting octopus populations in Australia, Indonesia, Japan and the deep sea. This study experimentally assessed the social tolerance and presence of potential prey items of Caribbean reef octopus, Octopus briareus, in a tropical marine lake (25°21′40″N, 76°30′40″W) on the island of Eleuthera, The Bahamas, by deploying artificial dens in multi-den groups or ‘units’ in the months of May and June 2019. Fifteen octopus were observed occupying dens (n = 100), resulting in 13 den units being occupied (n = 40). Two examples of adjacent occupation within a single den unit were identified but with zero examples of cohabitation/den sharing. Ecological models showed den and den unit occupation was predicted to increase with depth and differ between sites. Octopus also displayed no preference for isolated or communal units but preferred isolated dens over dens adjacent to others. Additionally, 47 % of occupied dens contained bivalve or crustacean items with no epifauna on their interior surface. The lack of epifauna suggests that these items have been recently ‘cleaned’ by occupying octopus and so represent likely prey. This study presents evidence of possible antisocial den use by O. briareus, a modification of the default ‘asocial’ ignoring of conspecifics typically attributed to octopus. This is likely in response to the high population density and may imply behavioural plasticity, making this system appropriate for further scrutiny as a research location on the influence of large, insular environments on marine species.

scholarly journals Recruitment sex ratios in gray-tailed voles (Microtus canicaudus) in response to density, sex ratio, and season

2003 ◽  
Vol 81 (8) ◽  
pp. 1306-1311 ◽  
Author(s):  
Monica L Bond ◽  
Jerry O Wolff ◽  
Sven Krackow
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Resource Competition ◽  
Sex Ratios ◽  
Female Offspring ◽  
High Population ◽  
Reproductive Value ◽  
High Population Density ◽  
Adult Sex Ratio ◽  
Sex Ratio Adjustment

We tested predictions associated with three widely used hypotheses for facultative sex-ratio adjustment of vertebrates using eight enclosed populations of gray-tailed voles, Microtus canicaudus. These were (i) the population sex ratio hypothesis, which predicts that recruitment sex ratios should oppose adult sex-ratio skews, (ii) the local resource competition hypothesis, which predicts female-biased recruitment at low adult population density and male-biased recruitment at high population density, and (iii) the first cohort advantage hypothesis, which predicts that recruitment sex ratios should be female biased in the spring and male biased in the autumn. We monitored naturally increasing population densities with approximately equal adult sex ratios through the spring and summer and manipulated adult sex ratios in the autumn and measured subsequent sex ratios of recruits. We did not observe any significant sex-ratio adjustment in response to adult sex ratio or high population density; we did detect an influence of time within the breeding season, with more female offspring observed in the spring and more male offspring observed in the autumn. Significant seasonal increases in recruitment sex ratios indicate the capacity of female gray-tailed voles to manipulate their offspring sex ratios and suggest seasonal variation in the relative reproductive value of male and female offspring to be a regular phenomenon.

scholarly journals Quantitative effects of defaunation on rumen fermentation and digestion in sheep

1985 ◽  
Vol 54 (1) ◽  
pp. 105-119 ◽  
Author(s):  
J. B. Rowe ◽  
A. Davies ◽  
A. W. J. Broome
Keyword(s):  
Organic Matter ◽  
Population Density ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Dietary Carbohydrate ◽  
High Population Density ◽  
Irreversible Loss ◽  
Faecal Excretion ◽  
Carbon And Nitrogen ◽  
End Products

1. Studies on the quantitative significance of protozoa on carbon and nitrogen digestion and metabolism in the rumen were carried out in sheep given a diet of pelleted concentrate (500 g/d) and chopped hay (500 g/d).2. Measurements were made of apparent digestibility; flows of organic matter and dietary and microbial non-ammonia N (NAN) (using 15NH+4) to the duodenum; and rates of production, interconversion and metabolism of the major C fermentation end-products (from mathematical modelling of 14C isotope values).3. The population density of bacteria in the rumen increased as a result of defamation (28.6 compared with 8.2 x 10° organisms/ml). This high density was associated with greater utilization of volatile fatty acids (VFA) within the rumen.4. The rate of irreversible loss (IL) of bicarbonatefcarbon dioxide from the rumen was greater in the defaunated animals (98.5 v. 57.2 g C/d) but the IL from the blood was greater in the faunated group (138.6 v. 106.1 g C/d). This is consistent with the hypothesis that the high population density of bacteria found in the rumen fluid of defaunated animals may result in increased fermentation of rumen VFA and digestible dietary carbohydrate, thereby increasing the output of CO2 from the rumen and reducing the quantity of VFA (hence energy) available to the host.5. There was no difference in the flow of organic matter (OM) to the duodenum but there was a higher faecal excretion of OM in defaunated animals (apparent OM digestibility: 0.72 in faunated, 0.67 in defaunated).6. Defamation did not significantly increase the flow of NAN to the duodenum, the percentage of duodenal NAN of bacterial origin or the quantity of microbial NAN synthesized/g organic matter fermented. Faecal excretion of NAN was higher in defaunated animals (5.3 v. 3.6 g N/d).

The impact of urban form on disaster resiliency

2016 ◽  
Vol 7 (3) ◽  
pp. 259-275 ◽  
Author(s):  
Leila Irajifar ◽  
Neil Sipe ◽  
Tooran Alizadeh
Keyword(s):  
Land Use ◽  
Population Density ◽  
Urban Form ◽  
Disaster Recovery ◽  
Form Factors ◽  
High Density ◽  
Disaster Resilience ◽  
Content Type ◽  
Land Use Mix ◽  
The Impact

Purpose This paper examines the impact of urban form on disaster resiliency. The literature shows a complex relationship between urban form factors such as density and diversity and disaster recovery. The empirical analysis in this paper tests the impact of land use mix, population density, building type and diversity on the reconstruction progress in three, six and nine months after the 2010 flood in Brisbane and Ipswich as proxies of disaster resilience. Considerable debate exists on whether urban form factors are the causal incentive or are they mediating other non-urban form causal factors such as income level. In view of this, the effects of a series of established non-urban form factors such as income and tenure, already known as effective factors on disaster resilience, are controlled in the analysis. Design/methodology/approach The structure of this paper is based on a two-phase research approach. In the first phase, for identification of hypothetical relationships between urban form and disaster resiliency, information was gathered from different sources on the basis of theory and past research findings. Then in phase two, a database was developed to test these hypothetical relationships, employing statistical techniques (including multivariate regression and correlation analysis) in which disaster recovery was compared among 76 suburbs of Brisbane and Ipswich with differing levels of population density and land use mix. Findings The results indicate that population density is positively related to disaster resilience, even when controlling for contextual variables such as income level and home ownership. The association between population density and disaster reconstruction is non-linear. The progress of reconstruction to population density ratio increases from low, medium to high densities, while in very low and very high density areas the reconstruction progress does not show the same behavior, which suggests that medium-high density is the most resilient. Originality/value The originality of this paper is in extracting hypothetical relationships between urban form and resiliency and testing them with real world data. The results confirmed the contribution of density to recovery process in this case study. This illustrates the importance of attention to disaster resiliency measures from the early stages of design and planning in development of resilient urban communities.

Can differences between continental and insular habitats influence the parasites communities associated with the endemic frog Haddadus binotatus?

2020 ◽  
Vol 94 ◽  
Author(s):  
A. Aguiar ◽  
D.H. Morais ◽  
F.H. Yamada ◽  
L.A. dos Anjos ◽  
L.A.F. da Silva ◽  
...  
Keyword(s):  
Population Density ◽  
Parasite Transmission ◽  
Helminth Parasites ◽  
High Population Density ◽  
Geographic Isolation ◽  
Transmission Success ◽  
Parasite Richness ◽  
Continental Islands ◽  
Colonization Process ◽  
The Mean

Abstract Habitats characterized by geographic isolation such as islands have been studied using different organisms as models for understanding the dynamic and insular patterns of biodiversity. Determinants of parasite richness in insular host populations have been conducted mainly with mammals and birds, showing that parasite richness decreases in insular areas. In the present study, we predicted that the type of environment (insular or continental) can influence the richness, diversity and abundance of parasites associated with the endemic frog Haddadus binotatus (Spix, 1824). We sampled frogs in two insular and two mainland fragments to survey their helminth parasites. The total richness was composed of 15 taxa of Nematoda and two of Acanthocephala, and the community composition of the two islands had more similarities between them than the two mainland localities. The insular effect was positive for richness and abundance of helminths, and no significant effect was observed on helminth diversity – even the mean diversity presented high numbers for the islands. We presumed that insular hosts could have lost some parasites in the colonization process when these continental islands were separated from the mainland, approximately 11,000 years ago. However, the high richness and abundance on islands can be explained by an epidemiological argument, which considers high population density due to insularity and other features of the host as factors that increase parasite transmission success among individuals.

Aggregations of masked shrews ( Sorex cinereus ): density-related mating behavior? / Agrégation de musaraignes masquées ( Sorex cinereus ): accouplement relatif à la densité de la population?

Mammalia ◽  
2006 ◽  
Vol 70 (1-2) ◽  
Author(s):  
Thomas J. Maier ◽  
Katherine L. Doyle
Keyword(s):  
Population Density ◽  
Mating Behavior ◽  
High Population ◽  
High Population Density ◽  
Genetic Analyses ◽  
Highly Active ◽  
Sorex Cinereus

AbstractLarge aggregations of shrews have been reported and various explanations offered for this seemingly rare behavior; however, there has been little evidence to support any particular interpretation. We observed two small aggregations of highly active vocalizing Sorex cinereus while performing wildlife surveys in forested habitats in central Massachusetts, USA. These observations, in conjunction with a review of other reports, including genetic analyses, strongly suggest that such aggregations of adult Sorex are associated with mating behavior, more readily observed during periods of high population density. Published accounts of such behavior may be rare because primarily large aggregations have been reported; however, smaller breeding aggregations may be common.

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