Patch exploitation strategies of parasitoids: The role of sex ratio and forager's interference in structuring metapopulations

2012 ◽  
Vol 230 ◽  
pp. 11-21 ◽  
Author(s):  
Carolina Reigada ◽  
Sabrina B.L. Araujo ◽  
M.A.M. de Aguiar
Keyword(s):  
Sex Ratio ◽  
Patch Exploitation

Using Meta-analysis to Test Ecological and Evolutionary Theory

2013 ◽  
Author(s):  
Michael D. Jennions ◽  
Christopher J. Lortie ◽  
Julia Koricheva
Keyword(s):  
Sexual Selection ◽  
Sex Ratio ◽  
Case Studies ◽  
Evolutionary Theory ◽  
Meta Analysis ◽  
Basic Research ◽  
Fighting Behavior ◽  
Main Research ◽  
Sex Ratio Theory

This chapter describes nine case studies that illustrate how meta-analysis has contributed to theoretical developments in basic research in ecology and evolution. The main research topics cover are maintenance of biodiversity (Case 1); sexual selection (mate choice/fighting behavior) (cases 2, 8, 9); sex ratio theory (Case 3); allometric scaling (Case 4); the invasiveness of exotic plants (Case 5); seed size and plant abundance (Case 6); and the role of competition and predation in structuring communities (Case 7). It is hoped that these case studies will resonate with the reader and provide “templates” for ways to conduct comparable tests on analogous controversies in their own fields of research.

Translocation reverses birth sex ratio bias depending on its timing during gestation: evidence for the action of two sex-allocation mechanisms

2007 ◽  
Vol 19 (7) ◽  
pp. 831 ◽  
Author(s):  
W. L. Linklater
Keyword(s):  
Glucose Metabolism ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Preimplantation Embryo ◽  
Sex Ratio Bias ◽  
In Captivity ◽  
Developmental Asynchrony ◽  
Adjustment Mechanisms ◽  
Excess Glucose

Many sex allocation mechanisms are proposed but rarely have researchers considered and tested more than one at a time. Four facultative birth sex ratio (BSR) adjustment mechanisms are considered: (1) hormone-induced conception bias; (2) sex-differential embryo death from excess glucose metabolism; (3) sex-differential embryo death from embryo–uterine developmental asynchrony; and (4) pregnancy hormone suppression and resource deprivation. All mechanisms could be switched on by the corticoadrenal stress response. A total of 104 female rhinoceroses (Rhinocerotidae), translocated from 1961 to 2004 at different stages of gestation or conceived soon after arrival in captivity, were used to test for a reversal in BSR bias as evidence for the action of multiple sex-allocation mechanisms. Translocation induced a statistically significant BSR reversal between early gestation (86% male births from 0 to 0.19 gestation) and mid-gestation (38% male from 0.2 to 0.79 gestation). Captivity also induced a strongly male-biased (67% male) BSR for conceptions after arrival in captivity. The results indicate the action of at least two sex-allocation mechanisms operating in sequence, confirm the important role of sex-differential embryo death around implantation and of stress in sex allocation, and lend support to suggestions that sex-differential glucose metabolism by the preimplantation embryo likely plays a role in facultative BSR adjustment.

scholarly journals Causes and consequences of adult sex ratio imbalance in a historical U.S. population

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160314 ◽  
Author(s):  
Ryan Schacht ◽  
Ken R. Smith
Keyword(s):  
Biological Sciences ◽  
Sex Ratio ◽  
Life History Traits ◽  
Male Mating ◽  
Age At First Birth ◽  
The Social ◽  
Adult Sex Ratio ◽  
Sex Ratio Imbalance ◽  
Animal Societies

The responsiveness of individuals to partner availability has been well-documented across the literature. However, there is disagreement regarding the direction of the consequences of sex ratio imbalance. Specifically, does an excess of males or females promote male–male mating competition? In an attempt to clarify the role of the adult sex ratio (ASR) on behaviour, here we evaluate both competing and complimentary expectations derived from theory across the social and biological sciences. We use data drawn from a historical, nineteenth century population in North America and target several life-history traits thought to be affected by partner availability: age at first birth, relationship status, completed fertility and longevity. Furthermore, we assess the role of various contributors to a population's ASR. We find that both the contributors to and consequences of sex ratio imbalance vary over time. Our results largely support predictions of greater male pairbond commitment and lesser male mating effort, as well as elevated bargaining power of women in response to female scarcity. After reviewing our findings, and others from across the literature, we highlight the need to adjust predictions in response to ASR imbalance by the: (i) culturally mediated mating arena, (ii) variable role of demographic inputs across time and place, (iii) constraints to behavioural outcomes across populations, and (iv) ability and accuracy of individuals to assess partner availability. This article is part of the themed issue ‘Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies’.

Conclusion

2017 ◽  
Author(s):  
Gregory L. Carter ◽  
Maryanne L. Fisher
Keyword(s):  
Sex Ratio ◽  
Operational Sex Ratio ◽  
Future Research ◽  
Female Competition ◽  
Mate Poaching ◽  
Attitudes And Behaviors ◽  
Theoretical Perspectives ◽  
Wide Range ◽  
Mate Copying

This handbook has presented a wide range of theoretical perspectives on the motivations, attitudes, and behaviors involved in female competition. Using a metatheoretical framework, the contributors have examined how, when, and why women compete. This conclusion articulates the book’s main themes, beginning with evidence regarding women as active, competitive individuals and the value of mating information, addressing topics such as women’s competitive choices regarding mate copying, mate poaching, and mate retention. It then considers the role of intrasexual aggression in adolescence in relation to dating and reproduction, the importance of Operational Sex Ratio (OSR) to female competition, the concept of cooperative mothering or allomothering, and infanticide. It also discusses women as competitors in both traditional and novel social arenas as well as the role of women’s physiology in their competitive behaviors. Finally, it suggests directions for future research on topics that warrant further scrutiny.

scholarly journals The role of maternal preconception vitamin D status in human offspring sex ratio

2019 ◽  
Vol 112 (3) ◽  
pp. e26-e27
Author(s):  
Alexandra C. Purdue-Smithe ◽  
Keewan Kim ◽  
Carrie J. Nobles ◽  
Enrique F. Schisterman ◽  
Karen C. Schliep ◽  
...  
Keyword(s):  
Vitamin D ◽  
Sex Ratio ◽  
Vitamin D Status ◽  
Offspring Sex Ratio ◽  
Offspring Sex

scholarly journals Sperm sex ratio adjustment in a mammal: perceived male competition leads to elevated proportions of female-producing sperm

2020 ◽  
Vol 16 (6) ◽  
pp. 20190929
Author(s):  
Renée C. Firman ◽  
Jamie N. Tedeschi ◽  
Francisco Garcia-Gonzalez
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Female Offspring ◽  
Male Competition ◽  
Offspring Sex ◽  
Sex Ratio Adjustment ◽  
Adaptive Adjustment ◽  
Male House

Mammal sex allocation research has focused almost exclusively on maternal traits, but it is now apparent that fathers can also influence offspring sex ratios. Parents that produce female offspring under conditions of intense male–male competition can benefit with greater assurance of maximized grand-parentage. Adaptive adjustment in the sperm sex ratio, for example with an increase in the production of X-chromosome bearing sperm (CBS), is one potential paternal mechanism for achieving female-biased sex ratios. Here, we tested this mechanistic hypothesis by varying the risk of male–male competition that male house mice perceived during development, and quantifying sperm sex ratios at sexual maturity. Our analyses revealed that males exposed to a competitive ‘risk’ produced lower proportions of Y-CBS compared to males that matured under ‘no risk’ of competition. We also explored whether testosterone production was linked to sperm sex ratio variation, but found no evidence to support this. We discuss our findings in relation to the adaptive value of sperm sex ratio adjustments and the role of steroid hormones in socially induced sex allocation.

The role of lemming herbivory in the sex ratio and shoot demography of willow populations

Oikos ◽  
2001 ◽  
Vol 92 (3) ◽  
pp. 459-466 ◽  
Author(s):  
Martin Predavec ◽  
Kjell Danell
Keyword(s):  
Sex Ratio
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