Obligate and Facultative Brood Reduction in Eagles: An Examination of Factors that Influence Fratricide

The Auk ◽  
1983 ◽  
Vol 100 (3) ◽  
pp. 630-635 ◽  
Author(s):  
Thomas C. Edwards ◽  
Michael W. Collopy
Keyword(s):  
Relative Size ◽  
Brood Reduction ◽  
Size Difference ◽  
Feeding Rates ◽  
Proximate Mechanisms ◽  
Offspring Sex ◽  
Locomotor Development ◽  
Relative Differences

Abstract Fratricide in eagles (Accipitridae: Accipitrinae) is either obligate [second hatched nestling (C2) always dies] or facultative (C2 occasionally dies) and appears to be a function of relative size differences between siblings. Several factors, including time between hatching, differences in hatching weights, and possibly the sex of the nestling in conjunction with its hatching sequence, influence size difference. Size differences are modified further by feeding rates of young by adults. These factors determine the relative differences in locomotor development and coordination and thus the ability of the first-hatched nestling to control access to and monopolize parent-provided resources. Significantly greater (P < 0.0001) within-clutch volume differences (an indicator of disparity in hatching weight) and greater time between hatching (mode of 3 versus 2 days) are found in eagles in which fratricide is obligate (three species) than in those in which fratricide is facultative (eight species). We suggest that these differences are proximate mechanisms that account for observed differences in the frequency of fratricide in eagles. Although size difference is determined in part by the sex and hatching sequence of the nestling, the role of offspring sex in fractricide is not clear.

TOLERATED CO-FEEDING IN RELATION TO DEGREE OF KINSHIP IN JAPANESE MACAQUES

Behaviour ◽  
2001 ◽  
Vol 138 (4) ◽  
pp. 487-509 ◽  
Author(s):  
Bernard Chapais ◽  
Patrick Belisle
Keyword(s):  
Macaca Fuscata ◽  
Japanese Macaques ◽  
Preferential Treatment ◽  
Feeding Rates ◽  
Dominance Relationship ◽  
Mothers And Daughters ◽  
Dominant Female ◽  
Different Types ◽  
Access To Food

AbstractWe analyzed co-feeding in relation to degree of kinship in Japanese macaques Macaca fuscata), testing experimentally five categories of matrilineal kin dyads: mother-daughter, grandmother-granddaughter, sisters, aunt-niece and nonkin. In each test, two adult females with a clear dominance relationship had access to a box containing a limited quantity of highly prized food. The dominant female could easily prevent the subordinate from eating so that food was easily monopolizable, hence the use of the expression tolerated co-feeding. Rates of tolerated co-feeding increased steeply with degree of kinship. The aggression levels of dominant females towards subordinate females decreased with increasing degree of kinship and this effect was most apparent between mothers and daughters. The confidence level of subordinate females increased with degree of kinship and this effect became apparent above the aunt-niece kin class. Prior access to food by the subordinate female was a significant means of access to food, mostly beyond the grandmother-granddaughter kin category. The results point to a relatedness threshold for the preferential treatment of kin at r = 0.25 (grandmother-granddaughter and sister dyads), beyond which (r = 0.125: aunt-niece dyads), levels of tolerated co-feeding were comparable to those of nonkin females. The identity of this threshold with that found in previous studies on the same group for two different types of interactions suggests the existence of a generalized relatedness threshold for kin favoritism in Japanese macaques. Assuming that the costs of food defense by the dominant females were negligible and that tolerated co-feeding was altruistic, our results support the role of kin selection in the evolution of altruism in primates beyond the mother-offspring bond.

scholarly journals Size-mediated, density-dependent cannibalism in the signal crayfish Pacifastacus leniusculus (Dana, 1852) (Decapoda, Astacidea), an invasive crayfish in Britain

Crustaceana ◽  
2017 ◽  
Vol 90 (4) ◽  
pp. 417-435 ◽  
Author(s):  
R. J. Houghton ◽  
C. Wood ◽  
X. Lambin
Keyword(s):  
Relative Size ◽  
Pacifastacus Leniusculus ◽  
Gut Contents ◽  
Size Distributions ◽  
Signal Crayfish ◽  
Density Dependent ◽  
Invasive Crayfish ◽  
The Relationship ◽  
Best Fit

The role of cannibalism in crayfish populations is not well understood, despite being a potentially key density-dependent process underpinning population dynamics. We studied the incidence of cannibalism in an introduced signal crayfish Pacifastacus leniusculus population in a Scottish lowland river in September 2014. Animals were sampled using six different sampling techniques simultaneously, revealing variable densities and size distributions across the site. Cannibalism prevalence was estimated by analysing the gut contents of crayfish >20 mm CL for the presence of crayfish fragments, which was found to be 20% of dissected individuals. When seeking evidence of relationships between the sizes of cannibals and ‘prey’, the density of conspecifics <56% the size of a dissected individual yielded the best fit. The relationship between cannibalism probability and crayfish size and density was equally well described by three different metrics of crayfish density. Cannibalism increased with crayfish size and density but did not vary according to sex. These results suggest that large P. leniusculus frequently cannibalize smaller (prey) conspecifics, and that the probability of cannibalism is dependent upon the relative size of cannibal-to-prey and the density of the smaller crayfish. We suggest that removing large individuals, as targeted by many traditional removal techniques, may lead to reduced cannibalism and therefore a compensatory increase in juvenile survival.

scholarly journals Ecophysiology of egg rejection in hosts of avian brood parasites: new insights and perspectives

2021 ◽  
Author(s):  
Francisco Ruiz-Raya
Keyword(s):  
Potential Role ◽  
Physiological State ◽  
Host Responses ◽  
Future Research ◽  
Egg Rejection ◽  
Fitness Costs ◽  
Brood Parasites ◽  
Proximate Mechanisms ◽  
Proximate Factors

Abstract Egg rejection is the most effective and widespread defence used by host species to counteract the extreme fitness costs frequently imposed by obligate avian brood parasites. Yet, the proximate mechanisms underlying between- and within-individual variation in host responses remain poorly explored. Emerging evidence suggests that egg rejection is dependent on individual physiological state, and draws attention to the role of hormones as mediators of flexible antiparasitic responses. In this perspective article, I outline recent advances in our understanding of the proximate factors that mediate egg rejection. I also point out some areas where knowledge remains still lacking, especially those related to the development and maintenance of effective cognitive functions, the potential role of oxidative stress, immunological state and developmental stressors. I propose new hypotheses that stimulate future research on behavioural host responses towards brood parasitism.

scholarly journals Differences in acid phosphomonoesterase activity in forest soils of the Smrk Massive in the Moravskoslezské Beskydy Mts. (Czech Republic)

Beskydy ◽  
2012 ◽  
Vol 5 (2) ◽  
pp. 135-152
Author(s):  
A. Bajer ◽  
P. Samec ◽  
M. Žárník
Keyword(s):  
Relative Size ◽  
Chemical Properties ◽  
Principal Component ◽  
European Beech ◽  
Soil Characteristics ◽  
Strong Correlations ◽  
Spruce Stands ◽  
The Individual ◽  
A Site

The purpose of this paper is to determine the individual relations between APEA and specific soils and environmental factors. To disclose these relations, analysis of component vectors and principal component analysis (PCA) were performed. Vectors of soil characteristics with participation of APEA (aAKFE) and vectors of pedochemical variables (aCHEM) were also calculated. Their ratio (ia) indicated the relative size of the APEA impact on the relations between pedochemical characteristics. Based on the statistical analyses, different role of APEA in Norway spruce and in European beech stands was detected. While APEA in spruce stands did not show significant correlations with the other examined soil chemical properties, soils under beech stands displayed strong correlations with some of the pedochemical variables. The idea of this research is to find out whether APEA could be used as an indicator of forest vegetation status and of the anthropogenic load on a site.

Cocaine‐induced inhibition of process outgrowth in locus coeruleus neurons: role of gestational exposure period and offspring sex

2004 ◽  
Vol 22 (5-6) ◽  
pp. 297-308 ◽  
Author(s):  
Diane M. Snow ◽  
Heidi M. Carman ◽  
Jeffrey D. Smith ◽  
Rosemarie M. Booze ◽  
Marian A. Welch ◽  
...  
Keyword(s):  
Locus Coeruleus ◽  
Exposure Period ◽  
Gestational Exposure ◽  
Offspring Sex ◽  
Process Outgrowth

scholarly journals The Bathtub Illusion

i-Perception ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 204166951985359 ◽  
Author(s):  
Marco Bertamini
Keyword(s):  
Size Difference

When a person looks at the fingers of their own hand as they line up in depth, the impression may emerge that the little fingers, which are farther away, are located too far and if so they are not part of the same hand. I describe the conditions and suggest this is due to the size difference between fingers (size-distance scaling). A role of size on perceived distance here is more powerful than knowledge about our own body.

scholarly journals The behavioral response of prey fish to predators: the role of predator size

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3222 ◽  
Author(s):  
Zhong-Hua Tang ◽  
Qing Huang ◽  
Hui Wu ◽  
Lu Kuang ◽  
Shi-Jian Fu
Keyword(s):  
Relative Size ◽  
The Body ◽  
Size Difference ◽  
Prey Fish ◽  
Potential Predator ◽  
Black Carp ◽  
Predator Treatment ◽  
Predator Size ◽  
Significant Difference ◽  
Spontaneous Activities

Predation is one of the key factors governing patterns in natural systems, and adjustments of prey behaviors in response to a predator stimulus can have important ecological implications for wild fish. To investigate the effects of predators on the behavior of prey fish and to test whether the possible effects varied with predator size, black carp (Mylopharyngodon piceus) and snakehead (Channa argus) (a size-matched predator treatment with a similar body size to prey fish and a larger predator treatment with approximately 2.7 times of the body mass of prey fish) were selected to function as prey and predator, respectively. Their spontaneous activities were videorecorded in a central circular arena surrounded by a ring holding the stimulus fish. The distance between prey and predator fish was approximately 200% of the distance between two prey fish, which suggested that black carp can distinguish their conspecifics from heterospecifics and probably recognize the snakehead as a potential predator. The prey fish spent substantially less time moving and exhibited an overall shorter total distance of movement after the size-matched or large predator was introduced, which possibly occurred due to increased vigilance or efforts to reduce the possibility of detection by potential predators. However, there was no significant difference in either distance or spontaneous activities between two predator treatments. These findings suggested that (1) an anti-predator strategy in black carp might involve maintaining a safe distance, decreasing activity and possibly increased vigilance and that (2) the behaviors of prey response to predators were not influenced by their relative size difference.

Homologous chromosome pairing in meiosis of higher eukaryotes—still an enigma?

Genome ◽  
2020 ◽  
Vol 63 (10) ◽  
pp. 469-482
Author(s):  
J. Sybenga
Keyword(s):  
Chromosome Pairing ◽  
Dna Sequences ◽  
Homologous Chromosome ◽  
Homology Search ◽  
Size Difference ◽  
Primary Role ◽  
Dna Double Strand Breaks ◽  
Homologous Chromosome Pairing ◽  
Higher Eukaryotes

Meiosis is the basis of the generative reproduction of eukaryotes. The crucial first step is homologous chromosome pairing. In higher eukaryotes, micrometer-scale chromosomes, micrometer distances apart, are brought together by nanometer DNA sequences, at least a factor of 1000 size difference. Models of homology search, homologue movement, and pairing at the DNA level in higher eukaryotes are primarily based on studies with yeast where the emphasis is on the induction and repair of DNA double-strand breaks (DSB). For such a model, the very large nuclei of most plants and animals present serious problems. Homology search without DSBs cannot be explained by models based on DSB repair. The movement of homologues to meet each other and make contact at the molecular level is not understood. These problems are discussed and the conclusion is that at present practically nothing is known of meiotic homologue pairing in higher eukaryotes up to the formation of the synaptonemal complex, and that new, necessarily speculative models must be developed. Arguments are given that RNA plays a central role in homology search and a tentative model involving RNA in homology search is presented. A role of actin in homologue movement is proposed. The primary role of DSBs in higher eukaryotes is concluded to not be in pairing but in the preparation of Holliday junctions, ultimately leading to chromatid exchange.

Expertise Fails to Attenuate Gendered Biases in Judicial Decision-Making

2018 ◽  
Vol 10 (2) ◽  
pp. 227-234 ◽  
Author(s):  
Andrea L. Miller
Keyword(s):  
Decision Making ◽  
Gender Ideology ◽  
Controlled Experiments ◽  
Judicial Decision ◽  
Trial Court ◽  
Judicial Decision Making ◽  
Legal Decision Making ◽  
Subject Matter Expertise ◽  
Relative Differences

Although the influence of gender ideology on lay decision-making has been established, it is not known to what extent expertise may mitigate gendered biases and improve decision-making quality. In a set of controlled experiments, trial court judges and laypeople evaluated a hypothetical child custody case and a hypothetical employment discrimination case. The role of expertise was tested in two ways: by comparing judges’ and laypeople’s decision-making and by examining relative differences in expertise among judges. Judges were no less influenced by litigant gender and by their own gender ideology than the lay sample. Judges with greater subject-matter expertise were also no less influenced by gender ideology than other judges. In some cases, expertise was associated with greater, not less, bias. The results of this study suggest that expertise does not attenuate gendered biases in legal decision-making.

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