Ecology of the dominant copepod species at a Low Arctic site

1985 ◽  
Vol 63 (5) ◽  
pp. 1138-1147 ◽  
Author(s):  
Paul D. N. Hebert
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Resource Use ◽  
Brood Size ◽  
Calanoid Copepod ◽  
Size Dependent ◽  
Body Sizes ◽  
Low Arctic ◽  
Herbivorous Species ◽  
Tundra Ponds

Four species of calanoid copepod regularly co-occur in tundra ponds near Churchill, Manitoba. Despite the physical uniformity of the habitats they occupy, twofold variation in body size and fivefold variation in brood size existed among conspecific populations of each species. Size shifts were concordant in the sexes, but the extent of sexual dimorphism was size dependent in each species. Size differences among populations persisted through two summers. The three herbivorous species showed parallel variation in body sizes and fecundities, while the predatory species did not. The size covariation in the herbivorous taxa may reflect significant overlap in resource use despite their size divergence.

Avian Egg Morphometrics - Allometric Models of Egg Volume, Clutch Volume and Shape

1994 ◽  
Vol 42 (3) ◽  
pp. 307 ◽  
Author(s):  
PD Olsen ◽  
RB Cunningham ◽  
CF Donnelly
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Clutch Size ◽  
Egg Volume ◽  
Simple Power ◽  
Wide Range ◽  
Body Weights ◽  
Body Sizes ◽  
Simple Power Function

This paper describes three comprehensive new models of the allometric relationships between egg volume, clutch volume and shape, and body weight. Mean egg dimensions, clutch sizes and adult body weights were obtained for 326 species, mainly of four bird types: raptors (including owls), shorebirds, frogmouths (including nightjars), and storks (including the New World vultures). These are groups in which there is a wide range of body sizes and of sexual dimorphism in body size (in direction and degree). Female body weight alone accounted for 92% of the variation in egg volume. Sexual dimorphism in body size, phylogenetic relationship, and clutch size were significant contributors to the model of egg volume; their addition increased the explained variance to over 98%. The model was curvilinear (quadratic) in form, rather than linear as assumed in previous models. Larger species laid smaller eggs than expected under a simple power function. For the fitted model, within bird types, generic groupings had parallel curvilinear slopes but differing intercepts. Between bird types, the slopes differed. Clutch volume was scaled to body weight; all the bird types had a common slope, which was curvilinear. Body weight and dimorphism accounted for 89.5% of the variation in clutch volume. For all bird types, eggs became proportionally longer in shape as body weight increased, according to a simple power law. The relevance of these relationships to hypotheses on the evolution and adaptive significance of sexual dimorphism and to the trade-off between egg size and clutch size is discussed briefly.

Allometry and sexual dimorphism in the lung morphology of prairie rattlesnakes, Crotalus viridis viridis

1999 ◽  
Vol 20 (4) ◽  
pp. 377-389 ◽  
Author(s):  
J. Scott Keogh ◽  
V. Wallach
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Intraspecific Variation ◽  
Relative Length ◽  
Single Population ◽  
Crotalus Viridis ◽  
Lung Morphology ◽  
Body Sizes ◽  
Vascular Component

AbstractWe quantified sexual dimorphism and allometric changes in the lung morphology of 160 juvenile and adult specimens of prairie rattlesnake, Crotalus viridis viridis, from a single population. In virtually all lung components, those of males are located more posteriorly than are those of females of the same body size. Males display a longer vascular component than females but there is no sexual dimorphism in size of the avascular component. Thus, males generally have longer lungs than do females at all body sizes. With increasing body size, the lung components are found more anteriorly, relative length of the vascular lung decreases, and relative length of the avascular lung increases in both sexes. However, total lung length increases isometrically with body size. These sexual and allometric differences suggest that intraspecific variation should be taken into account when lung size characters are used in snake systematic studies.

Interpopulational variation in sexual dimorphism, reproductive output, and parasitism of Liophis miliaris (Colubridae) in the Atlantic forest of Brazil

2006 ◽  
Vol 27 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Lígia Pizzatto ◽  
Otavio Marques
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Atlantic Forest ◽  
Reproductive Output ◽  
Sexual Size Dimorphism ◽  
The Other ◽  
Female Body Size ◽  
Body Sizes ◽  
Northern Atlantic ◽  
Males And Females

AbstractSexual maturity, sexual dimorphism, reproductive output, and parasitism of the colubrid snake Liophis miliaris were compared among populations inhabiting four regions of Brazil: (1) northern coastal Atlantic forest, (2) southern coastal Atlantic forest, (3) northern inland Atlantic forest (4) southern inland Atlantic forest. Females delayed maturity and attained larger body sizes than males in all regions. Males and females from northern Atlantic forest were smaller and attained maturity with a smaller body size than males of other regions. The sexual size dimorphism index ranged from 0.19 to 0.23 and was lowest in the northern Atlantic forest. There was no sexual dimorphism in head length in any of the populations studied. Clutch size was similar in all populations and increased with maternal body size. The reproductive frequency was lower in the northern coastal Atlantic forest and in contrast to the other regions, tended to increase with female body size. The nematoda Ophidiascaris sp. and cystacanths of Oligacanthorynchus spira (Acanthocephala) occurred equally in both sexes. Fewer snakes from the northern coastal Atlantic forest were infested by parasites compared to the other regions and parasitism apparently did not influence reproduction.

Growth, maturity, and sexual dimorphism in the wood turtle, Clemmys insculpta

1990 ◽  
Vol 68 (4) ◽  
pp. 672-677 ◽  
Author(s):  
Jeffrey E. Lovich ◽  
Carl H. Ernst ◽  
John F. McBreen
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Carapace Length ◽  
Sexual Size Dimorphism ◽  
Von Bertalanffy ◽  
Size Dimorphism ◽  
Adult Females ◽  
Body Sizes ◽  
Von Bertalanffy Growth Model ◽  
Wood Turtle

Growth in the wood turtle (Clemmys insculpta) is described using the von Bertalanffy growth model and nonlinear regression. Growth in both sexes is similar until about 160 mm plastron length. Males grew at a faster rate after this size. Males appear to mature at a larger size and later age than females, although age-specific body size is highly variable. Sexual size dimorphism, in carapace length, is pronounced, with males attaining mean body sizes significantly larger (1.07–1.10 times) than those of adult females. Plastron length is an inappropriate measure of sexual size dimorphism because of the development of plastral concavity in males. Females tend to predominate in samples, possibly owing to differential maturity of the sexes. The direction of sexual size dimorphism may be maintained by intrasexual competition among males for access to females. Data for several adults captured at intervals of from 9 to 20 years support the concept of indeterminate growth.

scholarly journals Body size dependent dispersal influences stability in heterogeneous metacommunities

2021 ◽  
Author(s):  
Kurt E. Anderson ◽  
Ashkaan K. Fahimipour
Keyword(s):  
Body Size ◽  
Food Web ◽  
Trophic Levels ◽  
Dispersal Rate ◽  
Ecological Stability ◽  
Size Dependent ◽  
Heterogeneous Habitat ◽  
Body Sizes ◽  
Demographic Processes ◽  
The Stability

AbstractBody size affects key biological processes across the tree of life, with particular importance for food web dynamics and stability. Traits influencing movement capabilities depend strongly on body size, yet the effects of allometrically-structured dispersal on food web stability are less well understood than other demographic processes. Here we study the stability properties of spatially-arranged model food webs in which larger bodied species occupy higher trophic positions, while species’ body sizes also determine the rates at which they traverse spatial networks of heterogeneous habitat patches. Our analysis shows an apparent stabilizing effect of positive dispersal rate scaling with body size compared to negative scaling relationships or uniform dispersal. However, as the global coupling strength among patches increases, the benefits of positive body size-dispersal scaling disappear. A permutational analysis shows that breaking allometric dispersal hierarchies while preserving dispersal rate distributions rarely alters qualitative aspects of metacommunity stability. Taken together, these results suggest that the oft-predicted stabilizing effects of large mobile predators may, for some dimensions of ecological stability, be attributed to increased patch coupling per se, and not necessarily coupling by top trophic levels in particular.

scholarly journals Body Size Dependent Dispersal Influences Stability in Heterogeneous Metacommunities

2021 ◽  
Author(s):  
Kurt Anderson ◽  
Ashkaan Fahimipour
Keyword(s):  
Body Size ◽  
Food Web ◽  
Trophic Levels ◽  
Dispersal Rate ◽  
Ecological Stability ◽  
Size Dependent ◽  
Heterogeneous Habitat ◽  
Body Sizes ◽  
Demographic Processes ◽  
The Stability

Abstract Body size affects key biological processes across the tree of life, with particular importance for food web dynamics and stability. Traits influencing movement capabilities depend strongly on body size, yet the effects of allometrically-structured dispersal on food web stability are less well understood than other demographic processes. Here we study the stability properties of spatially-arranged model food webs in which larger bodied species occupy higher trophic positions, while species' body sizes also determine the rates at which they traverse spatial networks of heterogeneous habitat patches. Our analysis shows an apparent stabilizing effect of positive dispersal rate scaling with body size compared to negative scaling relationships or uniform dispersal. However, as the global coupling strength among patches increases, the benefits of positive body size-dispersal scaling disappear. A permutational analysis shows that breaking allometric dispersal hierarchies while preserving dispersal rate distributions rarely alters qualitative aspects of metacommunity stability. Taken together, these results suggest that the oft-predicted stabilizing effects of large mobile predators may, for some dimensions of ecological stability, be attributed to increased patch coupling per se, and not necessarily coupling by top trophic levels in particular.

scholarly journals Body size dependent dispersal influences stability in heterogeneous metacommunities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kurt E. Anderson ◽  
Ashkaan K. Fahimipour
Keyword(s):  
Body Size ◽  
Food Web ◽  
Trophic Levels ◽  
Dispersal Rate ◽  
Ecological Stability ◽  
Size Dependent ◽  
Heterogeneous Habitat ◽  
Body Sizes ◽  
Demographic Processes ◽  
The Stability

AbstractBody size affects key biological processes across the tree of life, with particular importance for food web dynamics and stability. Traits influencing movement capabilities depend strongly on body size, yet the effects of allometrically-structured dispersal on food web stability are less well understood than other demographic processes. Here we study the stability properties of spatially-arranged model food webs in which larger bodied species occupy higher trophic positions, while species’ body sizes also determine the rates at which they traverse spatial networks of heterogeneous habitat patches. Our analysis shows an apparent stabilizing effect of positive dispersal rate scaling with body size compared to negative scaling relationships or uniform dispersal. However, as the global coupling strength among patches increases, the benefits of positive body size-dispersal scaling disappear. A permutational analysis shows that breaking allometric dispersal hierarchies while preserving dispersal rate distributions rarely alters qualitative aspects of metacommunity stability. Taken together, these results suggest that the oft-predicted stabilizing effects of large mobile predators may, for some dimensions of ecological stability, be attributed to increased patch coupling per se, and not necessarily coupling by top trophic levels in particular.

scholarly journals Unidirectional response to bidirectional selection on body size. I. Phenotypic, life history and endocrine response

2018 ◽  
Author(s):  
Clémentine Renneville ◽  
Alexis Millot ◽  
Simon Agostini ◽  
David Carmignac ◽  
Gersende Maugars ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Small Body ◽  
Large Body ◽  
Detailed Knowledge ◽  
Control Line ◽  
Large Body Size ◽  
Size Dependent ◽  
Body Sizes ◽  
Anthropogenic Perturbations

ABSTRACTAnthropogenic perturbations such as harvesting often select against a large body size and are predicted to induce rapid evolution towards smaller body sizes and earlier maturation. However, body-size evolvability and, hence, adaptability to anthropogenic perturbations remain seldom evaluated in wild populations. Here, we use a laboratory experiment over 6 generations to measure the ability of wild-caught medaka fish (Oryzias latipes) to evolve in response to bidirectional size-dependent selection mimicking opposite harvest regimes. Specifically, we imposed selection against a small body size (Large line), against a large body size (Small line) or random selection (Control line), and measured correlated responses across multiple phenotypic, life-history and endocrine traits. As expected, the Large line evolved faster somatic growth and delayed maturation, but also evolved smaller body sizes at hatch, with no change in average levels of pituitary gene expressions of luteinizing, folliclestimulating or growth (GH) hormones. In contrast, the Small medaka line was unable to evolve smaller body sizes or earlier maturation, but evolved smaller body sizes at hatch and showed marginally-significant signs of increased reproductive investment, including larger egg sizes and elevated pituitary GH production. Natural selection on medaka body size was too weak to significantly hinder the effect of artificial selection, indicating that the asymmetric body-size response to size-dependent selection reflected an asymmetry in body-size evolvability. Our results show that trait evolvability may be contingent upon the direction of selection, and that a detailed knowledge of trait evolutionary potential is needed to forecast population response to anthropogenic change.

Reproduction and feeding of the colubrid snake Tomodon dorsatus from south-eastern Brazil

2005 ◽  
Vol 26 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Ivan Sazima ◽  
Otavio Marques ◽  
Alessandra Bizerra
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Rainy Season ◽  
Feeding Behaviour ◽  
South Eastern ◽  
Eastern Brazil ◽  
Body Sizes ◽  
Upper Jaw ◽  
Reproductive Cycles ◽  
Clutch Mass

AbstractBody size, sexual dimorphism, reproductive cycles, fecundity, diet and feeding behaviour of the colubrid snake Tomodon dorsatus from south-eastern Brazil were studied. Females of this viviparous species attained larger body sizes than males, the latter maturing with smaller body size than the former. Vitellogenesis occurred at the onset of rainy season, ovulation by mid rainy season, and parturition from late dry to early rainy season. Reproductive cycle was extended, maybe as a consequence of the low metabolism and food intake. Litter size ranged 4-26 offspring and was correlated with maternal body size. Relative clutch mass ranged 0.48-0.82, and neonates ranged 12-17 cm in snout-vent length. Tomodon dorsatus was shown to feed exclusively on veronicellid slugs quickly swallowed by long excursions of the specialized upper jaw units.

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.

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