scholarly journals Mechanisms of density dependence in juvenile salmonids: prey depletion, interference competition, or energy expenditure?

Ecosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
Author(s):  
Jean‐Michel O. Matte ◽  
Dylan J. Fraser ◽  
James W. A. Grant
Keyword(s):  
Energy Expenditure ◽  
Density Dependence ◽  
Interference Competition ◽  
Juvenile Salmonids ◽  
Prey Depletion

Density dependence of feeding success in haematophagous ectoparasites

Parasitology ◽  
2007 ◽  
Vol 134 (10) ◽  
pp. 1379-1386 ◽  
Author(s):  
B. R. KRASNOV ◽  
A. HOVHANYAN ◽  
I. S. KHOKHLOVA ◽  
A. A. DEGEN
Keyword(s):  
Density Dependence ◽  
Intraspecific Competition ◽  
Interference Competition ◽  
Host Defence ◽  
Defence System ◽  
Feeding Success ◽  
Alternative Hypotheses ◽  
Mean Size ◽  
The Mean ◽  
Host Defence System

SUMMARYWe studied the effect of density on feeding success of 2 fleas, Xenopsylla conformis and Xenopsylla ramesis, when exploiting rodents Meriones crassus and Gerbillus dasyurus. We tested 2 alternative hypotheses: (i) that intraspecific interference competition occurs and, thus, feeding success of a flea decreases with an increase in density and (ii) that facilitation via suppression of a host defence system occurs and thus, feeding success of a flea increases with an increase in density. The mean size of a bloodmeal and the proportion of highly engorged individuals in X. conformis feeding on both hosts were affected by density. When on G. dasyurus, both the size of a bloodmeal and the proportion of highly engorged individuals were lower at low (5–15 fleas per host) than at high (25–50 fleas per host) densities. The opposite was true when this flea fed on M. crassus. The mean bloodmeal size and proportions of highly engorged X. ramesis parasitizing either host were not affected by flea density. This study showed that the density dependence of feeding success of a flea (a) varied both between fleas and within-fleas between hosts and (b) indicated either intraspecific competition or facilitation via the host in a particular flea-host association.

Failure of physiological metrics to predict dominance in juvenile Pacific salmon (Oncorhynchus spp.): habitat effects on the allometry of growth in dominance hierarchies1Order of authors represents their contribution to the manuscript.

2011 ◽  
Vol 68 (10) ◽  
pp. 1811-1818 ◽  
Author(s):  
Travis E. Van Leeuwen ◽  
Jordan S. Rosenfeld ◽  
Jeffrey G. Richards
Keyword(s):  
Dominance Hierarchy ◽  
Pacific Salmon ◽  
Interference Competition ◽  
Fish Growth ◽  
Stream Channels ◽  
Juvenile Salmonids ◽  
Natural Stream ◽  
Mixed Support ◽  
Juvenile Pacific Salmon ◽  
Access To Food

Territoriality is one of the best examples of interference competition and generally results in larger, dominant individuals gaining preferential access to food. However, the expectation of higher growth of dominant individuals among juvenile salmonids has received only mixed support. We used outdoor semi-natural stream channels stocked with varying sizes of young of the year juvenile salmonids under high and low food rations (i) to examine the mechanisms underlying variation in the benefits of dominance and (ii) to demonstrate that inconsistencies in the apparent benefits of dominance are a logical outcome of the allometry of growth and differential energy intake among fish of different size in a dominance hierarchy. Growth of dominants exceeded that of subordinates when food was abundant, but subordinates grew faster than dominants in low food treatments and when dominant fish increased in size and approached the capacity of their habitat. In general, size disparity within a dominance hierarchy may promote higher growth of subdominants because of the lower energetic requirements of smaller individuals, and the allometry of fish growth, relative to habitat capacity, can reverse the expected growth and condition of dominant and subordinate fish.

scholarly journals Density dependence, prey accessibility and prey depletion by fisheries drive Peruvian seabird population dynamics

Ecography ◽  
2017 ◽  
Vol 41 (7) ◽  
pp. 1092-1102 ◽  
Author(s):  
Christophe Barbraud ◽  
Arnaud Bertrand ◽  
Marilú Bouchón ◽  
Alexis Chaigneau ◽  
Karine Delord ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Prey Depletion ◽  
Seabird Population

A compendium of G-protein–coupled receptors and cyclic nucleotide regulation of adipose tissue metabolism and energy expenditure

2020 ◽  
Vol 134 (5) ◽  
pp. 473-512 ◽  
Author(s):  
Ryan P. Ceddia ◽  
Sheila Collins
Keyword(s):  
Adipose Tissue ◽  
Energy Expenditure ◽  
Signaling Pathways ◽  
G Protein ◽  
Uncoupling Protein ◽  
Beige Adipocytes ◽  
Nucleotide Regulation ◽  
Ucp1 Expression ◽  
Thermogenic Adipocytes ◽  
G Protein Coupled

Abstract With the ever-increasing burden of obesity and Type 2 diabetes, it is generally acknowledged that there remains a need for developing new therapeutics. One potential mechanism to combat obesity is to raise energy expenditure via increasing the amount of uncoupled respiration from the mitochondria-rich brown and beige adipocytes. With the recent appreciation of thermogenic adipocytes in humans, much effort is being made to elucidate the signaling pathways that regulate the browning of adipose tissue. In this review, we focus on the ligand–receptor signaling pathways that influence the cyclic nucleotides, cAMP and cGMP, in adipocytes. We chose to focus on G-protein–coupled receptor (GPCR), guanylyl cyclase and phosphodiesterase regulation of adipocytes because they are the targets of a large proportion of all currently available therapeutics. Furthermore, there is a large overlap in their signaling pathways, as signaling events that raise cAMP or cGMP generally increase adipocyte lipolysis and cause changes that are commonly referred to as browning: increasing mitochondrial biogenesis, uncoupling protein 1 (UCP1) expression and respiration.

Energy Expenditure Scales

1987 ◽  
Author(s):  
P. Christopher Earley ◽  
Pauline Wojnaroski ◽  
William Prest
Keyword(s):  
Energy Expenditure

Energy expenditure and physical activity in patients with anorexia nervosa

2013 ◽  
Vol 121 (03) ◽  
Author(s):  
U Elbelt ◽  
V Haas ◽  
T Hofmann ◽  
S Jeran ◽  
H Pietz ◽  
...  
Keyword(s):  
Physical Activity ◽  
Anorexia Nervosa ◽  
Energy Expenditure

Impact of Type 1 Diabetes on 24-Hour Energy Expenditure and Metabolic Flexibility

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 1887-P ◽  
Author(s):  
ELVIS A. CARNERO ◽  
KAREN D. CORBIN ◽  
CHRISTOPHER P. BOCK ◽  
STEVEN R. SMITH ◽  
RICHARD E. PRATLEY
Keyword(s):  
Type 1 Diabetes ◽  
Energy Expenditure ◽  
Metabolic Flexibility

Neuronal Deletion of the Mammalian Indy Homolog (Slc13a5) Increases Energy Expenditure in Mice

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 1804-P
Author(s):  
ANICA KURZBACH ◽  
DIANA M. WILLMES ◽  
TINA SCHUMANN ◽  
CHRISTINE HENKE ◽  
NERMEEN EL-AGROUDY ◽  
...  
Keyword(s):  
Energy Expenditure
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