scholarly journals Perch Selection by Three Cooccurring Species ofCelithemis(Odonata: Libellulidae): Testing for a Competitive Hierarchy among Similar Species

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Wade B. Worthen ◽  
Parker H. Morrow
Keyword(s):  
Body Size ◽  
Niche Partitioning ◽  
Open Water ◽  
The Other ◽  
Similar Species ◽  
Male Body ◽  
Size Dependent ◽  
Anatomical Characters ◽  
Relative Abundances ◽  
Imagej Software

In many communities of perching dragonflies (Odonata: Libellulidae), a size-dependent competitive hierarchy creates a positive relationship between male body size and perch height. We tested for this pattern among three similar-sized species:Celithemis elisa,C. fasciata, andC. ornata.Males were caught and photographed from May to July 2015 at Ashmore Heritage Preserve, Greenville County, SC, USA, and perch heights and perch distance to open water were measured. Five indices of body size were measured with ImageJ software: abdomen length, forewing length, hindwing length, area of forewing, and area of hindwing.Celithemis fasciatawas significantly larger than the other two species for all five anatomical characters and used perches that were significantly taller and closer to open water than the other species, though these differences changed over the summer. Aggressive interactions between and within species were tallied and compared to expected distributions based on mean relative abundances derived from hourly abundance counts. Patterns of interspecific aggression were also consistent with a size-dependent hierarchy: the largeC. fasciatawas attacked less frequently, and the smallC. ornatamore frequently, than predicted by their relative abundances. We conclude that even small differences in body size may contribute to niche partitioning in perch selection.

scholarly journals Predator–prey body size relationships when predators can consume prey larger than themselves

2013 ◽  
Vol 9 (3) ◽  
pp. 20121193 ◽  
Author(s):  
Takefumi Nakazawa ◽  
Shin-ya Ohba ◽  
Masayuki Ushio
Keyword(s):  
Body Size ◽  
Prey Size ◽  
The Other ◽  
Field Observations ◽  
Species Identity ◽  
Predator Prey ◽  
Size Dependent ◽  
Fish Predators ◽  
Body Sizes ◽  
Prey Mass

As predator–prey interactions are inherently size-dependent, predator and prey body sizes are key to understanding their feeding relationships. To describe predator–prey size relationships (PPSRs) when predators can consume prey larger than themselves, we conducted field observations targeting three aquatic hemipteran bugs, and assessed their body masses and those of their prey for each hunting event. The data revealed that their PPSR varied with predator size and species identity, although the use of the averaged sizes masked these effects. Specifically, two predators had slightly decreased predator–prey mass ratios (PPMRs) during growth, whereas the other predator specialized on particular sizes of prey, thereby showing a clear positive size–PPMR relationship. We discussed how these patterns could be different from fish predators swallowing smaller prey whole.

Interactions between body size and mating history influence the reproductive success of males of a tortricid moth, Zeiraphera canadensis

1994 ◽  
Vol 72 (12) ◽  
pp. 2124-2132 ◽  
Author(s):  
Allan L. Carroll
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Accessory Gland ◽  
Male Body ◽  
Male Body Size ◽  
Size Dependent ◽  
Mating History ◽  
Mating Receptivity ◽  
Spermatophore Size ◽  
Multiple Male

The independent and interacting effects of male body size, age, and previous number of matings on (i) spermatophore size and (ii) female reproductive performance were examined in the laboratory using Zeiraphera canadensis Mut. &Free. (Lepidoptera: Tortricidae). Spermatophore size was not influenced by male age, but large males produced larger spermatophores and their size decreased with the number of consecutive matings. The capacity of males to produce spermatophores on successive days was size dependent. Large males produced well-defined spermatophores over five consecutive copulations, whereas small males were no longer able to produce a discernible spermatophore by the fourth mating. Male body size and mating history, independently or in combination, did not affect female fecundity or longevity despite their influence on spermatophore size, suggesting that potential spermatophore-derived nutrients were not utilized for reproduction or somatic maintenance. However, the number of previous matings on consecutive days influenced successful insemination as well as the receptivity of successfully inseminated females to additional matings. Moreover, the influence of multiple male matings on insemination success and mating receptivity was also size dependent. After several consecutive copulations, small males were less likely to successfully inseminate females and "switch off" the females' mating receptivity than large males. The size-dependent decline in ability to inseminate and switch off females, independent of spermatophore size, suggests that small males were more limited than large ones in their capacity to produce accessory gland secretions other than those required for spermatophore construction. Large Z. canadensis males may experience higher reproductive success than small ones by inseminating more females over consecutive evenings and leaving fewer females receptive to remating.

Body Dissatisfaction: The Ideal Body and a Summary of Theories of Development and Maintenance

2020 ◽  
Author(s):  
Daniel Talbot
Keyword(s):  
Body Size ◽  
Body Dissatisfaction ◽  
Muscle Tone ◽  
Subjective Evaluation ◽  
Male Body ◽  
Ideal Body ◽  
Physiological Outcomes ◽  
The Ideal

Body dissatisfaction can be defined as a negative subjective evaluation of one’s body as a whole, or relating to specific aspects of one’s body such as body size, shape, muscularity/muscle tone, and weight. Prior research has found that body dissatisfaction is associated with a number of negative psychological and physiological outcomes. This commentary describes the Western ideal male body, as well as providing a summary of theories of the cause and maintenance of male body dissatisfaction.

scholarly journals Chest beats as an honest signal of body size in male mountain gorillas (Gorilla beringei beringei)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Edward Wright ◽  
Sven Grawunder ◽  
Eric Ndayishimiye ◽  
Jordi Galbany ◽  
Shannon C. McFarlin ◽  
...  
Keyword(s):  
Body Size ◽  
Competitive Ability ◽  
Dominance Rank ◽  
Male Body ◽  
Honest Signal ◽  
Sexual Competition ◽  
Mountain Gorillas ◽  
Temporal Characteristics ◽  
Gorilla Beringei Beringei ◽  
Vocal Signals

AbstractAcoustic signals that reliably indicate body size, which usually determines competitive ability, are of particular interest for understanding how animals assess rivals and choose mates. Whereas body size tends to be negatively associated with formant dispersion in animal vocalizations, non-vocal signals have received little attention. Among the most emblematic sounds in the animal kingdom is the chest beat of gorillas, a non-vocal signal that is thought to be important in intra and inter-sexual competition, yet it is unclear whether it reliably indicates body size. We examined the relationship among body size (back breadth), peak frequency, and three temporal characteristics of the chest beat: duration, number of beats and beat rate from sound recordings of wild adult male mountain gorillas. Using linear mixed models, we found that larger males had significantly lower peak frequencies than smaller ones, but we found no consistent relationship between body size and the temporal characteristics measured. Taken together with earlier findings of positive correlations among male body size, dominance rank and reproductive success, we conclude that the gorilla chest beat is an honest signal of competitive ability. These results emphasize the potential of non-vocal signals to convey important information in mammal communication.

scholarly journals Three-dimensional niche partitioning between two colonially nesting ardeid species in central China

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuanxing Ye ◽  
Canshi Hu ◽  
Yiting Jiang ◽  
Geoffrey W. H. Davison ◽  
Changqing Ding
Keyword(s):  
Niche Partitioning ◽  
Trophic Niche ◽  
Egg Laying ◽  
Central China ◽  
Paddy Fields ◽  
Shaanxi Province ◽  
Similar Species ◽  
Wetland Birds ◽  
Cattle Egret ◽  
River Banks

Abstract Background Interspecific competition is known to be strongest between those species that are both closely related and sympatric. Egrets are colonially nesting wetland birds that often overlap and can therefore be expected to compete in roosting and nesting habitat as well as in diet. According to the niche partitioning hypothesis, it is to be expected that these similar species would show differentiation in at least one of the main niche dimensions to reduce competition. We tested niche partitioning between the colonially nesting Little Egret (Egretta garzetta) and Cattle Egret (Bubulcus ibis) in temporal, spatial and trophic dimensions. Methods Field study was conducted in three mixed egret colonies in Yangxian County, southwest Shaanxi Province, central China. For each nest colony we recorded its spatial location, the height of nesting trees and of nests, the height of roosting trees and of roosting individuals within the trees. We determined the first egg-laying and first hatching dates of the two species. Craw dissection of storm-killed egret nestlings was used to measure the diet. Six transects were surveyed to study foraging habitat selection. Results We found that hatching time of Little Egrets peaked earlier (by about 1 month) than that of Cattle Egrets. Cattle Egrets nested and roosted higher than Little Egrets. The foraging habitats used by Little Egrets were dominated by river banks (73.49%), followed by paddy fields (13.25%) and reservoirs (10.84%), whereas Cattle Egret foraging sites were characterized by grasslands (44.44%), paddy fields (33.33%) and river banks (22.22%). Little Egrets consumed more fishes (65.66%) and Odonata larvae (13.69%) than Cattle Egrets, while Cattle Egrets were found feeding mainly on Coleoptera (29.69%) and Orthoptera (23.29%). Little Egrets preyed on larger mean biomasses of food items than Cattle Egrets. Conclusions Our results confirm the niche partitioning hypothesis as a mechanism for coexistence among ecologically similar species. In two coexisting egret species, niche partitioning is multidimensional, such that the two coexistent species occupy differing ecological space based on all three temporal, spatial and trophic niche dimensions.

Body size-dependent Cd accumulation in the zebra mussel Dreissena polymorpha from different routes

Chemosphere ◽  
2017 ◽  
Vol 168 ◽  
pp. 825-831 ◽  
Author(s):  
Wen-Li Tang ◽  
Douglas Evans ◽  
Lisa Kraemer ◽  
Huan Zhong
Keyword(s):  
Body Size ◽  
Zebra Mussel ◽  
Dreissena Polymorpha ◽  
Cd Accumulation ◽  
Size Dependent

An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

Effect of behavioral variables on cooling rate of man in cold water

1975 ◽  
Vol 38 (6) ◽  
pp. 1073-1077 ◽  
Author(s):  
J. S. Hayward ◽  
J. D. Eckerson ◽  
M. L. Collis
Keyword(s):  
Body Size ◽  
Cooling Rate ◽  
Rectal Temperature ◽  
Body Surface ◽  
Cold Water ◽  
The Other ◽  
Ocean Water ◽  
Protective Behaviors ◽  
Control Behavior ◽  
Behavioral Variables

Five different behaviors of man while in cold ocean water (9–10 degrees C) were assessed for their effect on rate of progress into hypothermia. With subjects wearing lifejackets, two thermally protective behaviors were studied which reduce exposure to the water of areas of body surface with high relative heat loss potential. One was huddling of three persons and the other a self-huddle behavior (HELP or Heat Escape Lessening Posture). These two behaviors resulted in significant reductions of rectal temperature cooling rate of 66 per cent and 69 per cent, respectively, of that of a control behavior. With no flotation available, two survival swimming behaviors (treading water and drownproofing) were shown to result in significant increases in cooling rate to 134 per cent and 182 per cent, respectively, of the control behavior. Potential swimming distance of subjects wearing a life-jacket was 0.85 miles in water near 12 degrees C before predicted incapacitation by hypothermia. It was concluded that behavioral variables can be of major importance in determining survival time in cold water through modulation of cooling rate associated with other variables such as fatness, body size, and clothing.

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