scholarly journals Mate-finding dispersal reduces local mate limitation and sex bias in dispersal

2019 ◽  
Author(s):  
Abhishek Mishra ◽  
Sudipta Tung ◽  
V.R. Shree Sruti ◽  
Sahana V. Srivathsa ◽  
Sutirth Dey
Keyword(s):  
Behavioral Plasticity ◽  
Sex Bias ◽  
List Type ◽  
Allee Effects ◽  
Same Sex ◽  
Mate Finding ◽  
Density Effects ◽  
Spatial Sorting ◽  
Large Populations ◽  
Mate Limitation

AbstractSex-biased dispersal (SBD) often skews the local sex ratio in a population. This can result in a shortage of mates for individuals of the less-dispersive sex. Such mate limitation can lead to Allee effects in populations that are small or undergoing range expansion, consequently affecting their survival, growth, stability and invasion speed.Theory predicts that mate shortage can lead to either an increase or a decrease in the dispersal of the less-dispersive sex. However, neither of these predictions have been empirically validated.To investigate how SBD-induced mate limitation affects dispersal of the less-dispersive sex, we used Drosophila melanogaster populations with varying dispersal propensities. To rule out any mate-independent density effects, we examined the behavioral plasticity of dispersal in presence of mates as well as same-sex individuals with differential dispersal capabilities.In the presence of high-dispersive mates, the dispersal of both male and female individuals was significantly increased. However, the magnitude of this increase was much larger in males than in females, indicating that the former show greater mate-finding dispersal. Moreover, the dispersal of either sex did not change when dispersing alongside high- or low-dispersive individuals of the same sex. This suggested that the observed plasticity in dispersal was indeed due to mate-finding dispersal, and not mate-independent density effects.Strong mate-finding dispersal can diminish the magnitude of sex bias in dispersal. This can modulate the evolutionary processes that shape range expansions and invasions, depending on the population size. In small populations, mate-finding dispersal can ameliorate Allee effects. However, in large populations, it can dilute the effects of spatial sorting.

scholarly journals Mate‐finding dispersal reduces local mate limitation and sex bias in dispersal

2020 ◽  
Vol 89 (9) ◽  
pp. 2089-2098 ◽  
Author(s):  
Abhishek Mishra ◽  
Sudipta Tung ◽  
V. R. Shree Sruti ◽  
Sahana Srivathsa ◽  
Sutirth Dey
Keyword(s):  
Sex Bias ◽  
Mate Finding ◽  
Local Mate ◽  
Mate Limitation

Sexually transmitted infections and mate-finding Allee effects

2017 ◽  
Vol 114 ◽  
pp. 59-69 ◽  
Author(s):  
Luděk Berec ◽  
Eva Janoušková ◽  
Michal Theuer
Keyword(s):  
Sexually Transmitted Infections ◽  
Allee Effects ◽  
Mate Finding ◽  
Sexually Transmitted

scholarly journals Genetic Allee effects and their interaction with ecological Allee effects

2016 ◽  
Author(s):  
Meike J. Wittmann ◽  
Hanna Stuis ◽  
Dirk Metzler
Keyword(s):  
Population Size ◽  
Inbreeding Depression ◽  
Survival Probability ◽  
Allee Effect ◽  
Extinction Risk ◽  
List Type ◽  
Small Populations ◽  
Allee Effects ◽  
Deleterious Mutations ◽  
Lethal Equivalents

SummaryIt is now widely accepted that genetic processes such as inbreeding depression and loss of genetic variation can increase the extinction risk of small populations. However, it is generally unclear whether extinction risk from genetic causes gradually increases with decreasing population size or whether there is a sharp transition around a specific threshold population size. In the ecological literature, such threshold phenomena are called “strong Allee effects” and they can arise for example from mate limitation in small populations.In this study, we aim to a) develop a meaningful notion of a “strong genetic Allee effect”, b) explore whether and under what conditions such an effect can arise from inbreeding depression due to recessive deleterious mutations, and c) quantify the interaction of potential genetic Allee effects with the well-known mate-finding Allee effect.We define a strong genetic Allee effect as a genetic process that causes a population’s survival probability to be a sigmoid function of its initial size. The inflection point of this function defines the critical population size. To characterize survival-probability curves, we develop and analyze simple stochastic models for the ecology and genetics of small populations.Our results indicate that inbreeding depression can indeed cause a strong genetic Allee effect, but only if individuals carry sufficiently many deleterious mutations (lethal equivalents) on average and if these mutations are spread across sufficiently many loci. Populations suffering from a genetic Allee effect often first grow, then decline as inbreeding depression sets in, and then potentially recover as deleterious mutations are purged. Critical population sizes of ecological and genetic Allee effects appear to be often additive, but even superadditive interactions are possible.Many published estimates for the number of lethal equivalents in birds and mammals fall in the parameter range where strong genetic Allee effects are expected. Unfortunately, extinction risk due to genetic Allee effects can easily be underestimated as populations with genetic problems often grow initially, but then crash later. Also interactions between ecological and genetic Allee effects can be strong and should not be neglected when assessing the viability of endangered or introduced populations.

scholarly journals Fire synchronizes flowering and boosts reproduction in a widespread but declining prairie species

2020 ◽  
Vol 117 (6) ◽  
pp. 3000-3005 ◽  
Author(s):  
Stuart Wagenius ◽  
Jared Beck ◽  
Gretel Kiefer
Keyword(s):  
Fire Suppression ◽  
Allee Effects ◽  
Echinacea Angustifolia ◽  
Mate Finding ◽  
Flowering Synchrony ◽  
The North ◽  
Local Plant ◽  
Mating Opportunities ◽  
North American Prairie ◽  
In Fire

Fire is an important determinant of habitat structure and biodiversity across ecosystems worldwide. In fire-dependent communities, similar to the North American prairie, fire suppression contributes to local plant extinctions. Yet the demographic mechanisms responsible for species loss have not been directly investigated. We conducted a 21-y longitudinal study of 778 individual plants of Echinacea angustifolia, a widespread perennial species with chronically limited mating opportunities, to explore how fire affects reproduction. In a large preserve, with management units on different burn schedules, we investigated Echinacea mating scenes, which quantify isolation from potential mates and overlap in the timing of flowering, to determine the extent to which fire influences the potential for sexual reproduction. We demonstrate that fire consistently increased mating opportunities by synchronizing reproductive effort. Each fire occurred during fall or spring and stimulated flowering in the subsequent summer, thus synchronizing reproduction among years and increasing the proximity of potential mates after a fire. Greater within-season flowering synchrony in postfire mating scenes further increased mating potential. The improved postfire mating scene enhanced reproduction by increasing pollination efficiency. Seed set in scenes postfire exceeded other scenes by 55%, and annual fecundity nearly doubled (88% increase). We predict the reproductive benefits of synchronized flowering after fire can alleviate mate-finding Allee effects, promote population growth, and forestall local extirpation in small populations of Echinacea and many other prairie species. Furthermore, the synchronization of flowering by burning may improve mating opportunities, reproduction, and the likelihood of persistence for many other plant species in fire-dependent habitats.

scholarly journals Can't live with them, can't live without them? Balancing mating and competition in two-sex populations

2017 ◽  
Vol 284 (1865) ◽  
pp. 20171999 ◽  
Author(s):  
Aldo Compagnoni ◽  
Kenneth Steigman ◽  
Tom E. X. Miller
Keyword(s):  
Sex Ratio ◽  
Mating Success ◽  
Sex Ratios ◽  
Structured Populations ◽  
Allee Effects ◽  
Mate Finding ◽  
Frequency Dependent ◽  
Density Dependent ◽  
Positive Effects ◽  
Demographic Processes

Two-sex populations are usually studied through frequency-dependent models that describe how sex ratio affects mating, recruitment and population growth. However, in two-sex populations, mating and recruitment should also be affected by density and by its interactions with the sex ratio. Density may have positive effects on mating (Allee effects) but negative effects on other demographic processes. In this study, we quantified how positive and negative inter-sexual interactions balance in two-sex populations. Using a dioecious grass ( Poa arachnifera ), we established experimental field populations that varied in density and sex ratio. We then quantified mating success (seed fertilization) and non-mating demographic performance, and integrated these responses to project population-level recruitment. Female mating success was positively density-dependent, especially at female-biased sex ratios. Other demographic processes were negatively density-dependent and, in some cases, frequency-dependent. Integrating our experimental results showed that mate-finding Allee effects dominated other types of density-dependence, giving rise to recruitment that increased with increasing density and peaked at intermediate sex ratios, reflecting tension between seed initiation (greater with more females) and seed viability (greater with more males). Our results reveal, for the first time, the balance of positive and negative inter-sexual interactions in sex-structured populations. Models that account for both density- and sex ratio dependence, particularly in mating, may be necessary for understanding and predicting two-sex population dynamics.

Effects of Sex of Judge and Sex of Victim on Recommended Punishment of a Male Murderer in a Mock Scenario

2002 ◽  
Vol 91 (2) ◽  
pp. 533-536 ◽  
Author(s):  
Stuart J. McKelvie
Keyword(s):  
Death Penalty ◽  
Sex Bias ◽  
Prison Sentence ◽  
Same Sex ◽  
Female Victim ◽  
Male Victim ◽  
Two Samples ◽  
Extralegal Factors

Two samples of undergraduates (36 women, 7 men; 44 women, 45 men) read a mock transcript in which a murderer's victim was a man or a woman, after which they made prison sentence and death penalty judgments. Female judges gave longer sentences for the female victim than for the male victim, whereas male judges gave longer sentences for the male victim than for the female victim. This same-sex bias suggests that extralegal factors can affect judgments about sentencing.

scholarly journals A cascade of destabilizations: combining Wolbachia and Allee effects to eradicate insect pests

2016 ◽  
Author(s):  
Julie C. Blackwood ◽  
Roger Vargas ◽  
Xavier Fauvergue
Keyword(s):  
Pest Management ◽  
Allee Effect ◽  
Mating Disruption ◽  
Insect Pests ◽  
Control Strategies ◽  
Insect Pest ◽  
Host Population ◽  
Marginal Effect ◽  
List Type ◽  
Allee Effects

SummaryThe management of insect pests has long been dominated by the use of chemical insecticides, with the aim of instantaneously killing enough individuals to limit their damage. To minimize unwanted consequences, environmentally-friendly approaches have been proposed that utilize biological control and take advantage of intrinsic demographic processes to reduce pest populations.We address the feasibility of a novel pest management strategy based on the release of insects infected with Wolbachia, which causes cytoplasmic incompatibilities in its host population, into a population with a pre-existing Allee effect. We hypothesize that the transient decline in population size caused by a successful invasion of Wolbachia can bring the population below its Allee threshold and, consequently, trigger extinction.We develop a stochastic population model that accounts for Wolbachia-induced cytoplasmic incompatibilities in addition to an Allee effect arising from mating failures at low population densities. Using our model, we identify conditions under which cytoplasmic incompatibilities and Allee effects successfully interact to drive insect pest populations toward extinction. Based on our results, we delineate control strategies based on introductions of Wolbachia-infected insects.We extend this analysis to evaluate control strategies that implement successive introductions of two incompatible Wolbachia strains. Additionally, we consider methods that combine Wolbachia invasion with mating disruption tactics to enhance the pre-existing Allee effect.We demonstrate that Wolbachia-induced cytoplasmic incompatibility and the Allee effect act independently from one another: the Allee effect does not modify the Wolbachia-invasion threshold, and cytoplasmic incompatibilities only have a marginal effect on the Allee threshold. However, the interaction of these two processes can drive even large populations to extinction. The success of this method can be amplified by the introduction of multiple Wolbachia cytotypes as well as the addition of mating disruption.Our study extends the existing literature by proposing the use of Wolbachia introductions to capitalize on pre-existing Allee effects and consequently eradicate insect pests. More generally, it highlights the importance of transient dynamics, and the relevance of manipulating a cascade of destabilizatons for pest management.

Sex Differences in Rated Seriousness of Crimes

1992 ◽  
Vol 70 (3) ◽  
pp. 867-870 ◽  
Author(s):  
Katherine C. Kormos ◽  
Dean C. White ◽  
Charles I. Brooks
Keyword(s):  
College Students ◽  
Sex Differences ◽  
Female College Students ◽  
Sex Bias ◽  
Psychological Consequences ◽  
Same Sex ◽  
Female College

61 male and 84 female college students completed a 25-item “Attitudes Toward Crime” survey designed to examine ratings of seriousness of crimes. In the survey, the perpetrator of the crime was always a male, but the victim was either a male or a female. Also, subjects compared the seriousness of the crimes with respect to harmful psychological consequences for the victim versus harmful consequences for society at large. Analysis showed a same-sex bias which varied with the type of harm. Men saw little harm to society compared to women, but only when the victim was a man. When individual harm was the issue, however, women saw more harmful consequences than men, but only when the victim was a woman.

Sign in / Sign up

Export Citation Format

Share Document