scholarly journals An experimental test to separate the effects of male age and mating history on female mate choice

2020 ◽  
Vol 31 (6) ◽  
pp. 1353-1360 ◽  
Author(s):  
Upama Aich ◽  
Timothee Bonnet ◽  
Rebecca J Fox ◽  
Michael D Jennions
Keyword(s):  
Female Choice ◽  
Female Mate Choice ◽  
Adult Males ◽  
Visual Contact ◽  
Young Males ◽  
Male Age ◽  
Offspring Fitness ◽  
Mating History ◽  
Association Time ◽  
Older Males

Abstract Should females prefer older males as mates? Male survival to old age might indicate the presence of fitness-enhancing genes that increase offspring fitness. However, many correlational studies show that mating with older males can lower female fecundity and even reduce offspring fitness due to epigenetic or germline mutation effects. One problem in quantifying female choice based on male age is that age is usually confounded with mating history. This begs a question: Do females choose males based on their age or their mating history? The answer requires an experimental approach, but few such studies exist. Here, we test if experimentally induced variation in the mating history of old and young males (12-week difference in postmaturity age) affects female choice in the eastern mosquitofish (Gambusia holbrooki). To vary mating history, adult males were either allowed to freely mate with females for 3 weeks or they only had visual contact with females. Immediately thereafter, we ran four-choice mating trials, using association time, to test the effects of male age and mating history (2 × 2 design) on male attractiveness. Females did not show a clear preference for males based on either characteristic. This was not due to a lack of female choice: females spent significantly more time with larger males. In addition, female choice was significantly repeatable across four trials: twice as a virgin and twice as a nonvirgin. Finally, female mating status (virgin or nonvirgin) did not affect her choice of mate, although virgin females spent significantly more time associating with test males.

scholarly journals Separating the effects of male age and past mating effort on paternity success under sperm competition

2021 ◽  
Author(s):  
Upama Aich ◽  
Megan Head ◽  
Rebecca Fox ◽  
Michael D Jennions
Keyword(s):  
Sperm Competition ◽  
General Pattern ◽  
Male Mating ◽  
Mating Effort ◽  
Reproductive Senescence ◽  
Young Males ◽  
Male Age ◽  
Mating History ◽  
Paternity Success ◽  
Older Males

Older males often perform poorly under post-copulatory sexual selection. It is unclear, however, whether reproductive senescence is due to male age itself or the accumulated costs of the higher lifetime mating effort that is usually associated with male age. To date, very few studies have accounted for male mating history when testing for the effect of male age on sperm traits, and none test how age and past mating history influence paternity success under sperm competition. Here, we experimentally manipulate male mating history to tease apart its effects from that of age on ejaculate traits and paternity in the mosquitofish, Gambusia holbrooki. We found that old, naive males had more sperm than old, experienced males, while the reverse was true for young males. In contrast, neither male age nor mating history affected sperm velocity. Finally, using artificial insemination to experimentally control the number of sperm per male, we found that old males sired significantly more offspring than young males independent of their mating history. Our results highlight that the general pattern of male reproductive senescence described in many taxa may often be affected by two naturally confounding factors, male mating history and sperm age, rather than male age itself.

scholarly journals Male age alone predicts paternity success under sperm competition when effects of age and past mating effort are experimentally separated

2021 ◽  
Vol 288 (1955) ◽  
pp. 20210979
Author(s):  
Upama Aich ◽  
Megan L. Head ◽  
Rebecca J. Fox ◽  
Michael D. Jennions
Keyword(s):  
Sperm Competition ◽  
General Pattern ◽  
Male Mating ◽  
Mating Effort ◽  
Reproductive Senescence ◽  
Young Males ◽  
Male Age ◽  
Mating History ◽  
Paternity Success ◽  
Older Males

Older males often perform poorly under post-copulatory sexual selection. It is unclear, however, whether reproductive senescence is because of male age itself or the accumulated costs of the higher lifetime mating effort that is usually associated with male age. To date, very few studies have accounted for mating history and sperm storage when testing the effect of male age on sperm traits, and none test how age and past mating history influence paternity success under sperm competition. Here, we experimentally manipulate male mating history to tease apart its effects from that of age on ejaculate traits and paternity in the mosquitofish, Gambusia holbrooki . We found that old, naive males had more sperm than old, experienced males, while the reverse was true for young males. By contrast, neither male age nor mating history affected sperm velocity. Finally, using artificial insemination to experimentally control the number of sperm per male, we found that old males sired significantly more offspring than young males independently of their mating history. Our results highlight that the general pattern of male reproductive senescence described in many taxa may often be affected by two naturally confounding factors, male mating history and sperm age, rather than male age itself.

Genetic effects of kangaroo harvesting.

2004 ◽  
Vol 26 (1) ◽  
pp. 75 ◽  
Author(s):  
PT Hale
Keyword(s):  
Gene Diversity ◽  
Adult Males ◽  
Evolutionary Potential ◽  
Offspring Fitness ◽  
Fitness Traits ◽  
Commercial Harvest ◽  
Genetic Impact ◽  
Fitness Benefits ◽  
Older Males

There is concern that the commercial harvest of kangaroos (Macropus spp.) is affecting species fitness and evolutionary potential because the harvest selects for larger individuals, particularly males. This paper reviews the likely effect of selective harvesting on specific traits associated with fitness, including size, and on adaptive genotypes through generalised loss of gene diversity. Heritability for traits associated with fitness is low generally. The intensity of selection imposed by harvesting is low for several reasons: the geographic size of genetic populations is much larger than the harvest localities, which are therefore not closed but open with immigration acting to correct any change in allele frequencies through harvesting; the harvest targets kangaroos above a threshold weight that includes all adult males, not the largest males specifically; larger, older males may not confer significant fitness benefits on offspring; fitness traits are inherited through both sexes while males are targeted predominantly; populations are not at a selective equilibrium because food availability fluctuates, and the fittest is unlikely to be the largest. Comparisons of harvested and unharvested populations do not show any loss of gene diversity as a result of harvesting. The likelihood of a long-term genetic impact of kangaroo harvesting as currently practiced is negligible.

Musth and its effects on male–male and male–female associations in Asian elephants

2019 ◽  
Vol 101 (1) ◽  
pp. 259-270 ◽  
Author(s):  
P Keerthipriya ◽  
S Nandini ◽  
Hansraj Gautam ◽  
T Revathe ◽  
T N C Vidya
Keyword(s):  
Southern India ◽  
Adult Males ◽  
Age Classes ◽  
Asian Elephants ◽  
Young Males ◽  
Gain Access ◽  
Older Males ◽  
Term Data

Abstract Musth is an annual, asynchronous, rut-like phenomenon observed in male elephants. We examined whether musth is a roving strategy, and whether musth provides a temporary advantage to young males through increased access to female groups. We collected long-term data on the musth status, associations, and locations of male elephants in the Kabini population in southern India. We sighted older males more frequently in musth than younger males. We found a greater turnover of musth than non-musth males in the study area, suggesting that musth is a roving strategy, enabling males to travel widely and away from their non-musth range. Contrary to our expectation, young (15–30 years old) males spent a smaller proportion of their musth time than their non-musth time associating with females, and associated with similarly sized female groups irrespective of musth status. Old (> 30 years old) males spent only a slightly higher proportion of their musth time than non-musth time with female groups, but associated with larger female groups during musth. Although old males in musth associated with young non-musth males more often in the presence, than in the absence, of females, young males in musth were never sighted with old non-musth males in the presence of females. Therefore, the payoff from musth, as a strategy to gain access to females, was age-specific; musth in old males allowed for increased association with females, while musth in young males restricted their access to females. There was no spatial avoidance between musth and non-musth adult males at scales larger than immediate associations. Our results suggest that musth seems to be primarily a roving strategy for old males to find and associate with females and not a strategy for young males to gain a temporary advantage over old males, within the broad age-classes that we examined.

scholarly journals Effects of Male Age and Female Presence on Male Associations in a Large, Polygynous Mammal in Southern India: The Asian Elephant

2021 ◽  
Vol 9 ◽  
Author(s):  
P. Keerthipriya ◽  
S. Nandini ◽  
T. N. C. Vidya
Keyword(s):  
Social Learning ◽  
Social Organization ◽  
Asian Elephant ◽  
Southern India ◽  
Older Individuals ◽  
Adult Males ◽  
Young Males ◽  
Male Age ◽  
Study Population ◽  
Female Presence

We present a detailed study of male associations in the Asian elephant, using 6 years of data on identified, non-musth males. Adult males spent greater proportions of their time solitarily than in mixed-sex or in all-male groups. Old (over 30 years) males were sighted more frequently with their age-peers and less frequently with young (15–30 years) males than expected at random in all-male groups. Young males were not sighted more frequently with old males than with young males, and did not disproportionately initiate associations with old males. These results suggest that male associations, in the absence of females, may allow for old non-musth males to test strengths against age-peers. Social learning from older individuals did not seem to be important in male associations, unlike that observed in the African savannah elephant. We also found a constraint on the sizes of all-male groups, similar to that seen in female groups in our study population, and all-male groups were rarer and smaller than those in African savannah elephant. Although male associations were weak, most males had a significant top associate, with whom their association was the strongest, in female absence. In mixed-sex groups, male associations occurred at random, suggesting that males were tracking female groups independently. Differences in male social organization from that of the related African savannah elephant that occupies a similar niche possibly arise from differences in ecology.

Female Choice in Middendorff's Grasshopper-Warbler (Locustella Ochotensis)

The Auk ◽  
1986 ◽  
Vol 103 (4) ◽  
pp. 694-700 ◽  
Author(s):  
Hisashi Nagata
Keyword(s):  
Mate Choice ◽  
Female Choice ◽  
Morphological Characteristics ◽  
Female Mate Choice ◽  
Food Abundance ◽  
Territory Size ◽  
Territory Quality ◽  
Female Mate ◽  
Nest Sites ◽  
Grasshopper Warbler

Abstract Morphological and territorial factors that influence female mate choice were examined in the monogamous Middendorff's Grasshopper-Warbler (Locustella ochotensis) on an islet near Fukuoka, Japan. I assumed that pairing date corresponded with female mate choice. Pairing date was correlated with both territory size and food abundance but was not correlated with selected morphological characteristics of males. Territorial quality was assumed to be correlated with territory size because preferable food resources and nest sites were distributed randomly. I conclude that female mate choice was influenced by territory quality rather than by the morphological characteristics of males.

scholarly journals Correlates and Treatment Outcome of Risky Sexual Behaviour in Young Males with ADHD and Comorbid Alcohol Use Disorder: A Prospective Study

2019 ◽  
Vol 1 (1) ◽  
pp. 62-69
Author(s):  
Shankar Kumar ◽  
Yamini Devendran ◽  
Madhumitha N. S. ◽  
Javagal Amith Thejas
Keyword(s):  
Sexual Behavior ◽  
Alcohol Use ◽  
Perceived Stress ◽  
Risky Sexual Behavior ◽  
Alcohol Use Disorder ◽  
Self Report ◽  
Adult Males ◽  
Young Males ◽  
Severity Scores ◽  
Inattention And Hyperactivity

Background: Attention-deficit/hyperactivity disorder (ADHD) is associated with risky sexual behavior (RSB). Alcohol use and high perceived stress in young adulthood contributes to this association. Previous studies have not found methylphenidate to reduce RSB in ADHD, as the population had comorbidities such as mood disorders and antisocial personality disorder. We aimed to study (a) the association of RSB with ADHD and severity of alcohol use among adolescents and young adult males with ADHD who had comorbid alcohol use disorder and (b) the effect of treatment of ADHD using methylphenidate on RSB in this population at 3- and 6-month follow-ups. Methodology: The study had 31 participants who were selected by screening for RSBs using the sexual behavior section of the HIV Risk-taking Behavior Scale (HRBS) manual among a cohort of individuals with ADHD and early onset alcohol use. These individuals were also administered WHO ADHD self-report scale (ASRS), alcohol-use disorders identification test (AUDIT), perceived stress scale (PSS), and HRBS-sexual behavior section. They were then treated with methylphenidate and these assessments were repeated at 3 and 6 months. Results: Those having ADHD with RSB had higher total ADHD score ( P = .007) and inattention score ( p = .0001) than those without RSB. There was a significant correlation between the ADHD total score with alcohol-use severity ( r = 0.47), with RSB ( r = 0.34), and ADHD hyperactivity scores with alcohol-use severity ( r = 0.49) and with RSB ( r = 0.34). There was also a significant reduction of ADHD total, inattention and hyperactivity scores, alcohol-use severity scores, RSB and perceived stress scores with use of methylphenidate at 3- and 6-month follow-ups. Multiple logistic regression predicted reduction in ADHD total scores to reduce RSB (odds ratio [OR] = 1.26, P = .01). Conclusion: RSB was associated with severity of ADHD and alcohol use. Methylphenidate not only reduced ADHD severity but also alcohol-use severity and RSB, whose reduction was predicted by reduction in ADHD severity.

scholarly journals Relating Reactive and Proactive Aggression to Trait Driving Anger in Young and Adult Males: A Pilot Study Using Explicit and Implicit Measures

2021 ◽  
Vol 13 (4) ◽  
pp. 1850
Author(s):  
Veerle Ross ◽  
Nora Reinolsmann ◽  
Jill Lobbestael ◽  
Chantal Timmermans ◽  
Tom Brijs ◽  
...  
Keyword(s):  
Pilot Study ◽  
Cognitive Biases ◽  
Young Male ◽  
Proactive Aggression ◽  
Implicit Measures ◽  
Adult Males ◽  
Young Males ◽  
Targeted Interventions ◽  
Driving Anger ◽  
Reactive And Proactive Aggression

Driving anger and aggressive driving are main contributors to crashes, especially among young males. Trait driving anger is context-specific and unique from other forms of anger. It is necessary to understand the mechanisms of trait driving anger to develop targeted interventions. Although literature conceptually distinguished reactive and proactive aggression, this distinction is uncommon in driving research. Similar, cognitive biases related to driving anger, measured by a combination of explicit and implicit measures, received little attention. This pilot study related explicit and implicit measures associated with reactive and proactive aggression to trait driving anger, while considering age. The sample consisted of 42 male drivers. The implicit measures included a self-aggression association (i.e., Single-Target Implicit Association Test) and an attentional aggression bias (i.e., Emotional Stroop Task). Reactive aggression related positively with trait driving anger. Moreover, a self-aggression association negatively related to trait driving anger. Finally, an interaction effect for age suggested that only in young male drivers, higher proactive aggression related to lower trait driving anger. These preliminary results motivate further attention to the combination of explicit and implicit measures related to reactive and proactive aggression in trait driving anger research.

Dispersal patterns in a regional koala population in south-east Queensland

2003 ◽  
Vol 30 (3) ◽  
pp. 281 ◽  
Author(s):  
David S. Dique ◽  
Jim Thompson ◽  
Harriet J. Preece ◽  
Deidré L. de Villiers ◽  
Frank N. Carrick
Keyword(s):  
Urban Areas ◽  
Home Ranges ◽  
Adult Males ◽  
Dispersal Patterns ◽  
Young Males ◽  
Straight Line ◽  
The Social ◽  
Straight Line Distance ◽  
Males And Females ◽  
Natal Home

Koala dispersal was investigated as part of a detailed ecological study of a nationally significant koala population located 20 km south-east of Brisbane, Queensland. From 1996 to 2000, 195 koalas from three sites were captured and fitted with radio-collars. A total of 40 koalas (23 males and 17 females) dispersed from these sites. Most (93%) dispersing individuals were 20–36 months of age. Three adult females (more than 36 months old) dispersed and no adult males dispersed during the study. A significantly higher proportion of young males dispersed than females. Dispersal occurred between June and December, with most dispersal of males commencing in July and August and that of females commencing between September and November prior to, and early in, the annual breeding season. The mean straight-line distance between the natal and breeding home ranges for males and females was similar and was measured at 3.5 km (range 1.1–9.7 km) and 3.4 km (range 0.3–10.6 km) respectively. Dispersing males and females tended to successfully disperse south and west of their natal home ranges and were generally unable to successfully disperse to urban areas within the study area, as a high proportion of the mortality of dispersing koalas was associated with attacks by domestic dogs and with collisions with vehicles on roads. Information from other studies indicates that most young koalas disperse from their natal areas. It is likely that the social behaviour and mating systems of koala populations provide mechanisms for young koalas to disperse. The potential role of dispersal in the dynamics of regional koala populations is discussed.

scholarly journals Paternal effects correlate with female reproductive stimulation in the polyandrous ladybirdCheilomenes sexmaculata

2014 ◽  
Vol 104 (4) ◽  
pp. 480-485 ◽  
Author(s):  
M.A. Mirhosseini ◽  
J.P. Michaud ◽  
M.A. Jalali ◽  
M. Ziaaddini
Keyword(s):  
Female Reproduction ◽  
Paternal Effects ◽  
Female Fecundity ◽  
Adult Weight ◽  
Male Age ◽  
Mating History ◽  
Epigenetic Effects ◽  
Seminal Fluids ◽  
Egg Fertility ◽  
Male Factors

AbstractComponents of male seminal fluids are known to stimulate fecundity and fertility in females of numerous insect species and paternal effects on offspring phenotype are also known, but no studies have yet demonstrated links between male effects on female reproduction and those on progeny phenotype. In separate laboratory experiments employing 10-day-old virgin females ofCheilomenes sexmaculata(F.), we varied male age and mating history to manipulate levels of male allomones and found that the magnitude of paternal effects on progeny phenotype was correlated with stimulation of female reproduction. Older virgin males remained in copula longer than younger ones, induced higher levels of female fecundity, and sired progeny that developed faster to yield heavier adults. When male age was held constant (13 days), egg fertility declined as a function of previous male copulations, progeny developmental times increased, and the adult weight of daughters declined. These results suggest that male epigenetic effects on progeny phenotype act in concert with female reproductive stimulation; both categories of effects increased as a consequence of male celibacy (factor accumulation), and diminished as a function of previous matings (factor depletion). Male factors that influence female reproduction are implicated in sexual conflict and parental effects may extend this conflict to offspring phenotype. Whereas mothers control the timing of oviposition events and can use maternal effects to tailor progeny phenotypes to prevailing or anticipated conditions, fathers cannot. Since females remate and dilute paternity in polyandrous systems, paternal fitness will be increased by linking paternal effects to female fecundity stimulation, so that more benefits accrue to the male's own progeny.

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