Aggression in female mammals: Is it really rare?

1999 ◽  
Vol 22 (2) ◽  
pp. 218-218 ◽  
Author(s):  
Paul F. Brain
Keyword(s):  
Sexual Dimorphism ◽  
Short Duration ◽  
Physical Aggression ◽  
Animal Studies ◽  
Human Values ◽  
Sexual Competition ◽  
Laboratory Rodents ◽  
Selection Of

The view that female mammals are more docile appears to arise in part from imposing human values on animal studies. Many reports of sexual dimorphism in physical aggression favouring the male in laboratory rodents appear to select circumstances where that expectation is supported. Other situations that favour the expression of conflict in females have been (until recently) relatively little studied. Although female rodents generally do not show the “ritualised” forms of conflict that characterise male sexual competition, they can use notably damaging strategies (especially if they are of short duration). Such considerations might weigh in the selection of strategies by our own species.

scholarly journals Sex-biased immunity is driven by relative differences in reproductive investment

2014 ◽  
Vol 281 (1790) ◽  
pp. 20140333 ◽  
Author(s):  
Crystal M. Vincent ◽  
Darryl T. Gwynne
Keyword(s):  
Immune Response ◽  
Sex Differences ◽  
Immune System ◽  
Sexual Dimorphism ◽  
Parental Investment ◽  
Sex Role ◽  
Reproductive Investment ◽  
Paternal Investment ◽  
Sexual Competition ◽  
Relative Differences

Sex differences in immunity are often observed, with males generally having a weaker immune system than females. However, recent data in a sex-role-reversed species in which females compete to mate with males suggest that sexually competitive females have a weaker immune response. These findings support the hypothesis that sexual dimorphism in immunity has evolved in response to sex-specific fitness returns of investment in traits such as parental investment and longevity, but the scarcity of data in sex-reversed species prevents us from drawing general conclusions. Using an insect species in which males make a large but variable parental investment in their offspring, we use two indicators of immunocompetence to test the hypothesis that sex-biased immunity is determined by differences in parental investment. We found that when the value of paternal investment was experimentally increased, male immune investment became relatively greater than that of females. Thus, in this system, in which the direction of sexual competition is plastic, the direction of sex-biased immunity is also plastic and appears to track relative parental investment.

Selection of skull morphological traits for sexual dimorphism analysis

HOMO ◽  
2012 ◽  
Vol 63 (4) ◽  
pp. 258-274 ◽  
Author(s):  
D. Psonak ◽  
B. Kwiatkowska
Keyword(s):  
Sexual Dimorphism ◽  
Morphological Traits ◽  
Selection Of

Selection of Tourism Destination as a Representation of Human Values

2015 ◽  
Vol 3 (2) ◽  
pp. 95-108
Author(s):  
Beena Salim Saji ◽  
Mohit Vij ◽  
Sajal Kabiraj
Keyword(s):  
Human Values ◽  
Tourism Destination ◽  
Selection Of

scholarly journals Artificial sexual selection alters allometry in the stalk-eyed fly Cyrtodiopsis dalmanni (Diptera: Diopsidae)

1993 ◽  
Vol 62 (3) ◽  
pp. 213-222 ◽  
Author(s):  
Gerald S. Wilkinson
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Body Length ◽  
Sexually Dimorphic ◽  
Selected Lines ◽  
Variable Intensity ◽  
High Line ◽  
Cumulative Selection ◽  
Selection For ◽  
Selection Of

SummarySelection for increased and decreased ratio of eye span to body length was exerted on male stalk-eyed flies (Cyrtodiopsis dalmanni) from Malaysia using replicate selected and unselected lines. Response to selection was symmetrical. After 10 generations high line male eye span increased to 1·3 body lengths while low line male eye span declined to 1·1 body lengths. Realized heritabilities for eye span to body length ratio, estimated using regressions of deviations from unselected controls on cumulative selection differentials, were greater than zero for all four selected lines with average h2 = 0·35 + 0·06. The static linear allometric relationship between eye span and body length diverged between selected lines and rotated among selected line males in the same direction as among males in other sexually dimorphic diopsid species. Crosses between lines after 13 generations of selection indicate that the genes which influence relative eye span combine additively and do not exhibit sex linkage or maternal effects. The genetic correlation between the sexes, 0·29 + 0·05 as estimated by the regression of female on male change in eye span, did not prevent sexual dimorphism in eye span from diverging between lines. These results suggest that the exaggerated eye span of male C. dalmanni is maintained by natural selection opposing sexual selection rather than by lack of or asymmetry in additive genetic variation. Furthermore, the variation in sexual dimorphism for eye span-body length allometry observed among extant diopsid species is consistent with sexual selection of variable intensity acting on relative eye span.

scholarly journals Studying the cognitive states of animals: Epistemology, ethology and ethics

2009 ◽  
Vol 37 (3/4) ◽  
pp. 369-422
Author(s):  
Otto Lehto
Keyword(s):  
Animal Studies ◽  
Natural Philosophy ◽  
Relevant Literature ◽  
Natural World ◽  
Cognitive Ethology ◽  
Evolutionary Account ◽  
Cognitive States ◽  
History Of ◽  
Scientific Quest ◽  
Selection Of

The question of cognitive endowment in animals has been fiercely debated in the scientific community during the last couple of decades (for example, in cognitive ethology and behaviourism), and indeed, all throughout the long history of natural philosophy (from Plato and Aristotle, via Descartes, to Darwin). The scientific quest for an empirical, evolutionary account of the development and emergence of cognition has met with many philosophical objections, blind alleys and epistemological quandaries. I will argue that we are dealing with conflicting philosophical world views as well as conflicting empirical paradigms of research. After looking at some examples from the relevant literature of animal studies to elucidate the nature of the conflicts that arise, I propose, in strict Darwinian orthodoxy, that cognitive endowments in nature are subject to the sort of continuum and gradation that natural selection of fit variant forms tends to generate. Somewhere between the myth of “free” humans and the myth of “behaviourally conditioned” animals lies the reality of animal behaviour and cognition. In the end, I hope to have softened up some of those deep-seated philosophical problems (and many quasi-problems) that puzzle and dazzle laymen, scientists and philosophers alike in their quest for knowledge about the natural world.

1. Darwin’s other big idea

2018 ◽  
pp. 1-15 ◽  
Author(s):  
Leigh W. Simmons
Keyword(s):  
Sexual Selection ◽  
Female Choice ◽  
Egg Production ◽  
Sexual Differences ◽  
The Other ◽  
Sexual Competition ◽  
Sexual Characteristics ◽  
Sexual Selection Theory ◽  
Males And Females ◽  
Selection Of

The idea that males and females often look, sound, smell, and behave differently is uncontroversial. Where those differences came from, however, and what role they play in various species—including humans—is not. ‘Darwin’s other big idea’ outlines Charles Darwin’s sexual selection theory: differential reproduction based on sexual competition, whether between the members of one sex for access to the other, or by selection of particular mating partners. Differences in reproductive parts directly involved in sperm or egg production—primary sexual characteristics—were relatively easy to explain. The other kinds of sexual differences, he proposed, could evolve in one of two ways: male–male competition resulting in weapons, or female choice resulting in ornaments, but this was highly controversial.

scholarly journals The majority of β-catenin mutations in colorectal cancer is homozygous

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Alexander Arnold ◽  
Moritz Tronser ◽  
Christine Sers ◽  
Aysel Ahadova ◽  
Volker Endris ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Lines ◽  
Animal Studies ◽  
Mutational Status ◽  
Mutational Hotspots ◽  
A Cell ◽  
Cytoplasmic Accumulation ◽  
Selection Of ◽  
Extracolonic Cancers ◽  
E Cadherin

Abstract Background β-catenin activation plays a crucial role for tumourigenesis in the large intestine but except for Lynch syndrome (LS) associated cancers stabilizing mutations of β-catenin gene (CTNNB1) are rare in colorectal cancer (CRC). Previous animal studies provide an explanation for this observation. They showed that CTNNB1 mutations induced transformation in the colon only when CTNNB1 was homozygously mutated or when membranous β-catenin binding was hampered by E-cadherin haploinsufficiency. We were interested, if these mechanisms are also found in human CTNNB1 mutated CRCs. Results Among 869 CRCs stabilizing CTNNB1 mutations were found in 27 cases. Homo- or hemizygous CTNNB1 mutations were detected in 74% of CTNNB1 mutated CRCs (13 microsatellite instabile (MSI-H), 7 microsatellite stabile (MSS)) but only in 3% (1/33) of extracolonic CTNNB1 mutated cancers. In contrast to MSS CRC, CTNNB1 mutations at codon 41 or 45 were highly selected in MSI-H CRC. Of the examined three CRC cell lines, β-catenin and E-cadherin expression was similar in cell lines without or with hetereozygous CTNNB1 mutations (DLD1 and HCT116), while a reduced E-cadherin expression combined with cytoplasmic accumulation of β-catenin was found in a cell line with homozygous CTNNB1 mutation (LS180). Reduced expression of E-cadherin in human MSI-H CRC tissue was identified in 60% of investigated cancers, but no association with the CTNNB1 mutational status was found. Conclusions In conclusion, this study shows that in contrast to extracolonic cancers stabilizing CTNNB1 mutations in CRC are commonly homo- or hemizygous indicating a higher threshold of β-catenin stabilization to be required for transformation in the colon as compared to extracolonic sites. Moreover, we found different mutational hotspots in CTNNB1 for MSI-H and MSS CRCs suggesting a selection of different effects on β-catenin stabilization according to the molecular pathway of tumourigenesis. Reduced E-cadherin expression in CRC may further contribute to higher levels of transcriptionally active β-catenin, but it is not directly linked to the CTNNB1 mutational status.

scholarly journals A Decade of Progress in Deep Brain Stimulation of the Subcallosal Cingulate for the Treatment of Depression

2020 ◽  
Vol 9 (10) ◽  
pp. 3260 ◽  
Author(s):  
Sharafuddin Khairuddin ◽  
Fung Yin Ngo ◽  
Wei Ling Lim ◽  
Luca Aquili ◽  
Naveed Ahmed Khan ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Deep Brain Stimulation ◽  
Medial Prefrontal Cortex ◽  
Brain Stimulation ◽  
Animal Studies ◽  
Great Promise ◽  
Comprehensive Overview ◽  
Treatment Of Depression ◽  
Selection Of ◽  
Deep Brain

Major depression contributes significantly to the global disability burden. Since the first clinical study of deep brain stimulation (DBS), over 446 patients with depression have now undergone this neuromodulation therapy, and 29 animal studies have investigated the efficacy of subgenual cingulate DBS for depression. In this review, we aim to provide a comprehensive overview of the progress of DBS of the subcallosal cingulate in humans and the medial prefrontal cortex, its rodent homolog. For preclinical animal studies, we discuss the various antidepressant-like behaviors induced by medial prefrontal cortex DBS and examine the possible mechanisms including neuroplasticity-dependent/independent cellular and molecular changes. Interestingly, the response rate of subcallosal cingulate Deep brain stimulation marks a milestone in the treatment of depression. DBS achieved response and remission rates of 64–76% and 37–63%, respectively, from clinical studies monitoring patients from 6–24 months. Although some studies showed its stimulation efficacy was limited, it still holds great promise as a therapy for patients with treatment-resistant depression. Overall, further research is still needed, including more credible clinical research, preclinical mechanistic studies, precise selection of patients, and customized electrical stimulation paradigms.

scholarly journals Reduced susceptibility to amoxicillin of oral streptococci following amoxicillin exposure

2009 ◽  
Vol 58 (8) ◽  
pp. 1092-1097 ◽  
Author(s):  
H. Chardin ◽  
K. Yasukawa ◽  
N. Nouacer ◽  
C. Plainvert ◽  
P. Aucouturier ◽  
...  
Keyword(s):  
Short Duration ◽  
Tooth Extraction ◽  
Bacterial Resistance ◽  
Odontogenic Infection ◽  
Oral Streptococci ◽  
Oral Flora ◽  
Clinical Efficiency ◽  
The Impact ◽  
Selection Of

As antibiotic pressure often triggers bacterial resistance, the use of short-duration therapies is increasingly recommended. The objective of the present study was to evaluate both the clinical efficiency and the impact on oral streptococci of a 3 day versus a 7 day amoxicillin therapy for odontogenic infection requiring tooth extraction. On day 0, patients were randomly assigned to a 3 day or 7 day amoxicillin treatment. The tooth was extracted on day 2 and the post-operative follow-up was carried out on day 9. Oral flora was collected on days 0, 9 and 30, and the susceptibility of the streptococci to amoxicillin was determined. The results showed that treatment with amoxicillin for 3 or 7 days had a similar clinical efficiency, and also induced similar selection of oral streptococci with reduced susceptibility to amoxicillin, suggesting that the selection of strains with reduced susceptibility to amoxicillin is a rapid phenomenon, appearing even with short-duration therapies.

scholarly journals Evolution and extinction can occur rapidly: a modeling approach

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11130
Author(s):  
Vitaly A. Likhoshvai ◽  
Tamara M. Khlebodarova
Keyword(s):  
Sexual Dimorphism ◽  
Ecosystem Functioning ◽  
Fossil Record ◽  
Life Forms ◽  
Living Systems ◽  
Adaptive Diversification ◽  
Self Development ◽  
Emergence Of Life ◽  
Selection Of ◽  
Reproduction Efficiency

Fossil record of Earth describing the last 500 million years is characterized by evolution discontinuity as well as recurring global extinctions of some species and their replacement by new types, the causes of which are still debate. We developed a model of evolutionary self-development of a large ecosystem. This model of biota evolution based on the universal laws of living systems functioning: reproduction, dependence of reproduction efficiency and mortality on biota density, mutational variability in the process of reproduction and selection of the most adapted individuals. We have shown that global extinctions and phases of rapid growth and biodiversity stasis can be a reflection of the emergence of bistability in a self-organizing system, which is the Earth’s biota. Bistability was found to be characteristic only for ecosystems with predominant sexual reproduction. The reason for the transition from one state to another is the selection of the most adapted individuals. That is, we explain the characteristics of the Earth’s fossil record during the last 500 million years by the internal laws of Earth’s ecosystem functioning, which appeared at a certain stage of evolution as a result of the emergence of life forms with an increased adaptive diversification associated with sexual dimorphism.

Sign in / Sign up

Export Citation Format

Share Document