Relationships between body mass, population density, and the self-thinning rule in stream-living salmonids

1997 ◽  
Vol 54 (5) ◽  
pp. 1025-1030 ◽  
Author(s):  
J B Dunham ◽  
G L Vinyard
Keyword(s):  
Body Size ◽  
Population Density ◽  
Body Mass ◽  
Experimental Studies ◽  
Fish Population ◽  
Population Characteristics ◽  
Causal Mechanisms ◽  
Temporal And Spatial Variability ◽  
Temporal And Spatial ◽  
Species Specific

In food and (or) space-limited populations, increases in average body size may be accompanied by increases in per capita space and (or) energy requirements. Thus, as body size increases in time or space, the equilibrium number of individuals that can be supported in a given environment should decrease. This relationship, referred to as self-thinning, produces a negative linear relationship between log body size (mass) and log population density. We studied body mass - population density relationships in stream-living populations of several trout species from the intermountain western United States. Our analyses of relationships between body mass and population density demonstrated that self-thinning can be manifested through both temporal and spatial variability in fish population characteristics. Several populations did not show self-thinning, possibly due to species-specific traits, temporal and spatial environmental variation, or both. Thinning lines may not reveal specific causal mechanisms, but they appear to be real, density-dependent responses and thus offer a potentially useful method for studying fish populations. Experimental studies of self-thinning under more controlled conditions are needed, however, to identify causal mechanisms and eliminate alternative explanations for body size - abundance relationships.

scholarly journals Can snakes use yolk reserves to maximize body size at hatching?

2018 ◽  
Vol 65 (6) ◽  
pp. 627-631 ◽  
Author(s):  
Yan-Fu Qu ◽  
Shu-Zhan Zhao ◽  
Xu-Fei Jiang ◽  
Long-Hui Lin ◽  
Xiang Ji
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Tail Length ◽  
Linear Size ◽  
Egg Mass ◽  
Fat Bodies ◽  
Free Body ◽  
Species Specific ◽  
Naja Atra

Abstract We experimentally miniaturized freshly laid eggs of the Chinese cobra Naja atra (Elapidae) by removing ∼10% and ∼20% of original yolk. We tested if yolk-reduced eggs would produce 1) normal-sized hatchlings with invariant yolk-free body mass (and thus invariant linear size) but dramatically reduced or even completely depleted residual yolk, 2) smaller hatchlings with normal-sized residual yolk but reduced yolk-free body mass, or 3) smaller hatchlings of which both yolk-free body mass and residual yolk are proportionally reduced. Yolk quantity affected hatchling linear size (both snout-vent length and tail length) and body mass. However, changes in yolk quantity did not affect incubation length or any hatchling trait examined after accounting for egg mass at laying (for control and sham-manipulated eggs) or after yolk removal (for manipulated eggs). Specifically, yolk-reduced eggs produced hatchlings of which all major components (carcass, residual yolk, and fat bodies) were scaled down proportionally. We show that snakes cannot use yolk reserves to maximize their body size at hatching. Furthermore, our data also suggest that the partitioning of yolk in embryonic snakes is species-specific.

The allometry of density within the space used by populations of mammalian Carnivora

2001 ◽  
Vol 79 (9) ◽  
pp. 1634-1640 ◽  
Author(s):  
K Shawn Smallwood
Keyword(s):  
Population Density ◽  
Body Mass ◽  
Mass Density ◽  
Density Estimates ◽  
Carnivore Species ◽  
Female Brain ◽  
Develop Theory ◽  
Allometric Analysis ◽  
Species Specific ◽  
The Relationship

The relationship between body mass and population density has been used to develop theory of how energy is used in ecosystems. The usual allometric density slope, –0.75, was reduced to near zero among species of mammalian Carnivora after Smallwood and Schonewald and Blackburn and Gaston adjusted density estimates by the sizes of the corresponding study areas. In this paper, I restricted the allometric analysis to density estimates made at or near the threshold area, which is the species-specific minimum area likely to support a population. I excluded densities estimated from subpopulations and "megapopulations", thereby removing biases of study design that had previously confused the allometry of population density. Density at threshold area declined with increasing body mass. The population's mass density did not relate to threshold area, within which carnivore species averaged 9 kg/km2. The spatial intensity of oxygen consumption did not relate to body mass, but assuming that species with smaller threshold areas occur at more locations than species with larger threshold areas, one must conclude that smaller bodied species use more energy from the environment than do larger bodied species. Furthermore, threshold area and density at threshold area were most responsive to female brain mass, which provides an ecological allometry that links spatial scale, sensory perception, parental care, life-history attributes, basal metabolic rate, and body mass.

The importance of meat, particularly salmon, to body size, population productivity, and conservation of North American brown bears

1999 ◽  
Vol 77 (1) ◽  
pp. 132-138 ◽  
Author(s):  
G V Hilderbrand ◽  
C C Schwartz ◽  
C T Robbins ◽  
M E Jacoby ◽  
T A Hanley ◽  
...  
Keyword(s):  
Body Size ◽  
Population Density ◽  
Body Mass ◽  
Litter Size ◽  
Adult Female ◽  
North American ◽  
Female Body ◽  
Brown Bears ◽  
Hair Samples ◽  
Female Body Mass

We hypothesized that the relative availability of meat, indicated by contribution to the diet, would be positively related to body size and population productivity of North American brown, or grizzly, bears (Ursus arctos). Dietary contributions of plant matter and meat derived from both terrestrial and marine sources were quantified by stable-isotope analysis (δ13C and δ15N) of hair samples from 13 brown bear populations. Estimates of adult female body mass, mean litter size, and population density were obtained from two field studies of ours and from other published reports. The populations ranged from largely vegetarian to largely carnivorous, and food resources ranged from mostly terrestrial to mostly marine (salmon, Oncorhynchus spp.). The proportion of meat in the diet was significantly correlated with mean adult female body mass (r = 0.87, P < 0.01), mean litter size (r = 0.72, P < 0.01), and mean population density (r = 0.91, P < 0.01). Salmon was the most important source of meat for the largest, most carnivorous bears and most productive populations. We conclude that availability of meat, particularly salmon, greatly influences habitat quality for brown bears at both the individual level and the population level.

scholarly journals An examination of the population dynamics of syngnathid fishes within Tampa Bay, Florida, USA

2010 ◽  
Vol 56 (1) ◽  
pp. 118-133 ◽  
Author(s):  
Heather D. Masonjones ◽  
Emily Rose ◽  
Lori Benson McRae ◽  
Danielle L. Dixson
Keyword(s):  
Population Dynamics ◽  
Body Size ◽  
Population Density ◽  
Late Summer ◽  
Open Water ◽  
Tampa Bay ◽  
Late Winter ◽  
Density Peaks ◽  
Under Construction ◽  
Species Specific

Abstract Seagrass ecosystems worldwide have been declining, leading to a decrease in associated fish populations, especially those with low mobility such as syngnathids (pipefish and seahorses). This two-year pilot study investigated seasonal patterns in density, growth, site fidelity, and population dynamics of Tampa Bay (FL) syngnathid fishes at a site adjacent to two marinas under construction. Using a modified mark-recapture technique, fish were collected periodically from three closely located sites that varied in seagrass species (Thalassia spp., Syringodium spp., and mixed-grass sites) and their distance from open water, but had consistent physical/chemical environmental characteristics. Fish were marked, photographed for body size and gender measurements, and released the same day at the capture site. Of the 5695 individuals surveyed, 49 individuals were recaptured, indicating a large, flexible population. Population density peaks were observed in July of both years, with low densities in late winter and late summer. Spatially, syngnathid densities were highest closest to the mouth of the bay and lowest near the shoreline. Seven species of syngnathid fishes were observed, and species-specific patterns of seagrass use emerged during the study. However, only two species, Syngnathus scovelli and Hippocampus zosterae, were observed at high frequencies. For these two species, body size decreased across the study period, but while S. scovelli's population density decreased, H. zosterae's increased. Across six of the seven species, population size declined over the course of this preliminary study; however, seasonal shifts were impossible to distinguish from potential anthropogenic effects of construction.

Life history, population characteristics and conservation of the Hungarian meadow viper (Vipera ursinii rakosiensis)

2000 ◽  
Vol 21 (3) ◽  
pp. 267-278 ◽  
Author(s):  
Zoltán Korsós ◽  
Beáta Újvári ◽  
Tamás Péchy
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Population Characteristics ◽  
Age Classes ◽  
In Captivity ◽  
Study Population ◽  
Annual Activity ◽  
Continuous Population ◽  
First Time ◽  
European Populations

AbstractDuring a continuous population study of Vipera ursinii rakosiensis, 79 specimens were measured in the field, between 1993 and 1997. Body length and body mass of six juveniles were compared to those of 43 more specimens which were kept during their first winter in terraria. Significant differences were found in favour of the juveniles kept in captivity, whereas a comparison with earlier data from 1953 showed a strong decline in juvenile body mass. Based on body size, three age classes could be distinguished in the study population. The annual activity and reproductive cycle of the Hungarian meadow viper is described for the first time. A comparison to other European populations of Orsini′s viper revealed a remarkably higher clutch size in Vipera ursinii rakosiensis, which is explained by the larger body size of females in the particular population.

Population biology of the crab Goniopsis cruentata: variation in body size, sexual maturity, and population density

2014 ◽  
Vol 64 (4) ◽  
pp. 383-394 ◽  
Author(s):  
José Jonathas Pereira Rodrigues de Lira ◽  
José Roberto Feitosa Silva ◽  
Carla Ferreira Rezende ◽  
Rogério Parentoni Martins ◽  
Tiago Osório Ferreira ◽  
...  
Keyword(s):  
Body Size ◽  
Environmental Factors ◽  
Population Density ◽  
Population Biology ◽  
Sexual Maturity ◽  
Life History Traits ◽  
Natural Populations ◽  
Population Characteristics ◽  
Mangrove Soil

We studied two key traits in the life of organisms, body size and sexual maturity, and a population attribute, density, of the crabGoniopsis cruentata. Also, we evaluated the role of environmental factors on population density. We caught crabs in two mangrove sites that are under different influence of tidal fluctuation, and obtained pH and salinity of mangrove soil from each site as well as rainfall data for the period of study. Both body size and sexual maturity differed between sites, in which individuals from the small-bodied population matured at smaller sizes than their counterparts from the large-bodied population, which matured at larger sizes. In addition, density of the small-bodied population was lower than that of the large-bodied one. We did not detect any influence of the environmental factors on population density. Our finding indicate that key life history traits and population characteristics can vary on a very small spatial scale which may help to further elucidate the biology of natural populations.

scholarly journals Morphological determinants of jumping performance in the Iberian green frog

2019 ◽  
Vol 66 (4) ◽  
pp. 417-424
Author(s):  
Gregorio Moreno-Rueda ◽  
Abelardo Requena-Blanco ◽  
Francisco J Zamora-Camacho ◽  
Mar Comas ◽  
Guillem Pascual
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Fluctuating Asymmetry ◽  
Hind Limb ◽  
Limb Length ◽  
Age Classes ◽  
Jumping Performance ◽  
Hind Limbs ◽  
Selective Forces ◽  
Pelophylax Perezi

Abstract Predation is one of the main selective forces in nature, frequently selecting potential prey for developing escape strategies. Escape ability is typically influenced by several morphological parameters, such as morphology of the locomotor appendices, muscular capacity, body mass, or fluctuating asymmetry, and may differ between sexes and age classes. In this study, we tested the relationship among these variables and jumping performance in 712 Iberian green frogs Pelophylax perezi from an urban population. The results suggest that the main determinant of jumping capacity was body size (explaining 48% of variance). Larger frogs jumped farther, but jumping performance reached an asymptote for the largest frogs. Once controlled by structural body size, the heaviest frogs jumped shorter distances, suggesting a trade-off between fat storage and jumping performance. Relative hind limb length also determined a small but significant percentage of variance (2.4%) in jumping performance—that is, the longer the hind limbs, the greater the jumping capacity. Juveniles had relatively shorter and less muscular hind limbs than adults (for a given body size), and their jumping performance was poorer. In our study population, the hind limbs of the frogs were very symmetrical, and we found no effect of fluctuating asymmetry on jumping performance. Therefore, our study provides evidence that jumping performance in frogs is not only affected by body size, but also by body mass and hind limb length, and differ between age classes.

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