Impact of male–male competition and morphological traits on mating strategies and reproductive success in broiler breeders

Polar bears ( Ursus maritimus ) from East Greenland and Svalbard exhibited very high concentrations of polychlorinated biphenyls (PCBs) in the 1980s and 1990s. In Svalbard, slow population growth during that period was suspected to be linked to PCB contamination. In this case study, we explored how PCBs could have impacted polar bear population growth and/or male reproductive success in Svalbard during the mid-1990s by reducing the fertility of contaminated males. A dose–response relationship linking the effects of PCBs to male polar bear fertility was extrapolated from studies of the effects of PCBs on sperm quality in rodents. Based on this relationship, an individual-based model of bear interactions during the breeding season predicted fertilization success under alternative assumptions regarding male–male competition for females. Contamination reduced pregnancy rates by decreasing the availability of fertile males, thus triggering a mate-finding Allee effect, particularly when male–male competition for females was limited or when infertile males were able to compete with fertile males for females. Comparisons of our model predictions on age-dependent reproductive success of males with published empirical observations revealed that the low representation of 10–14-year-old males among breeding males documented in Svalbard in mid-1990s could have resulted from PCB contamination. We conclude that contamination-related male infertility may lead to a reduction in population growth via an Allee effect. The magnitude of the effect is largely dependent on the population-specific mating system. In eco-toxicological risk assessments, appropriate consideration should therefore be given to negative effects of contaminants on male fertility and male mating behaviour.

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Male–male competition leads to less abundant but more attractive sperm

Biology Letters ◽

10.1098/rsbl.2013.0762 ◽

2013 ◽

Vol 9 (6) ◽

pp. 20130762 ◽

Cited By ~ 7

Author(s):

Z. Valentina Zizzari ◽

Nico M. van Straalen ◽

Jacintha Ellers

Keyword(s):

Reproductive Success ◽

Adaptive Response ◽

Mating Systems ◽

Male Competition ◽

Male Reproductive Success ◽

Optimization Strategy ◽

Relative Contribution ◽

Female Quality ◽

Rival Male ◽

Spermatophore Production

Males employ complex strategies to optimize their reproductive success when faced with male–male competition; for instance, they can adjust the ejaculate characteristics. In copulating species, a male may also strategically adjust his ejaculate expenditure according to female quality. Quantifying the relative contribution of ejaculate plasticity in male reproductive success is often difficult, especially when females exert postcopulatory cryptic choice. One way to quantify the functional significance of ejaculate plasticity is offered by mating systems in which the reproductive partners do not meet each other during insemination. In the collembolan Orchesella cincta , males deposit their ejaculates (spermatophores) irrespective of the presence of females. We tested whether Orchesella males adjust spermatophore number when exposed to the presence of another male and whether changes in spermatophore production influence female choice. We found that Orchesella males display plasticity in spermatophore allocation. Males decreased the spermatophore number when exposed to a rival male. Moreover, females preferentially took up spermatophores of males that were exposed to a competitor. The reduction in spermatophore number suggests, besides an adaptive response to the risk of ejaculate removal by rival males, an optimization strategy owing to the costs of more attractive spermatophores.

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Factors influencing male affiliation and coalitions in a species with male dispersal and intense male–male competition, Colobus vellerosus

Behaviour ◽

10.1163/1568539x-00003089 ◽

2014 ◽

Vol 151 (7) ◽

pp. 1045-1066 ◽

Cited By ~ 10

Author(s):

Julie A. Teichroeb ◽

Eva C. Wikberg ◽

Nelson Ting ◽

Pascale Sicotte

Keyword(s):

Reproductive Success ◽

Group Size ◽

Species Interactions ◽

Male Competition ◽

Adult Males ◽

Cooperative Relationships ◽

Colobus Vellerosus ◽

Male Dispersal ◽

Factors Influencing ◽

High Level

Male Colobus vellerosus compete intensely for access to females, which sometimes leads to mortal wounding. Yet, males often form cooperative relationships to overtake prime-aged males and immigrate into bisexual groups. We investigated the factors that predicted the presence of coalitions and affiliative relationships among males in this species. Interactions among males in 292 dyads from six groups were examined from 2004 to 2010 at Boabeng-Fiema, Ghana. Affiliation rates among males were higher and aggression rates lower when one or both males in the dyad were subadult, compared to adult male dyads. Affiliation rates tended to be higher among males that were kin but no other aspect of male relationships predicted affiliation. Coalitions among males were rarely observed and primarily occurred in the context of joint defense against extra-group males (93.5% of events). Adult males were more likely to provide coalitionary support than subadults and coalitions occurred significantly more often when both males were high ranking, since these males probably benefited most in terms of reproductive success from excluding extra-group males. Rank-changing and leveling coalitions among low-ranking males appear to be quite rare or absent in C. vellerosus. The costs of these types of coalitions may be too high or male group size too small on average for these types of coalitions to have been selected for. The overall low rates of affiliation and coalitions among male C. vellerosus are likely influenced by male-biased dispersal and the high level of male–male competition.

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Causes and consequences of variation in early-life telomere length in a bird metapopulation

10.32942/osf.io/9zctr ◽

2021 ◽

Author(s):

Michael Le Pepke ◽

Thomas Kvalnes ◽

Peter Sjolte Ranke ◽

Yimen G. Araya-Ajoy ◽

Jonathan Wright ◽

...

Keyword(s):

Reproductive Success ◽

Population Density ◽

Telomere Length ◽

Environmental Conditions ◽

Early Life ◽

Morphological Traits ◽

Weather Conditions ◽

Population Fluctuations ◽

Individual Quality ◽

Pace Of Life

1.Environmental conditions during early-life development can have lasting effects on individual quality and fitness. Telomere length (TL) may correlate with early-life conditions and may be an important mediator or biomarker of individual quality or pace-of-life, as periods of increased energy demands can increase telomere attrition due to oxidative stress. Thus, knowledge of the mechanisms that generate variation in TL, and the relation between TL and fitness, is important in understanding the role of telomeres in ecology and life-history evolution. 2.Here, we investigate how environmental conditions and morphological traits are associated with early-life TL and if TL predicts natal dispersal probability or components of fitness in two populations of wild house sparrows (Passer domesticus). 3.We measured morphological traits and blood TL in 2746 nestlings from 20 cohorts (1994-2013) and retrieved data on weather conditions. We monitored population fluctuations, and individual survival and reproductive output using field observations and genetic pedigrees. We then used generalized linear mixed-effects models to test which factors affected TL in early-life, and if TL predicted dispersal propensity, or was associated with recruitment probability, mortality risk, or reproductive success.4.We found a negative effect of population density on TL, but only in one of the populations. There was a curvilinear association between TL and the maximum daily North Atlantic Oscillation (NAO) index during incubation, suggesting that there are optimal weather conditions that result in the longest TL. Dispersers tended to have shorter telomeres than non-dispersers. TL did not predict survival, but we found a tendency for individuals with short telomeres to have higher annual reproductive success.5.Our study showed how early-life TL is shaped by effects of growth, weather conditions and population density, supporting that environmental stressors negatively affect TL in wild populations. In addition, TL may be a mediator or biomarker of individual pace-of-life, with higher dispersal rates and annual reproduction tending to be associated with shorter early-life TL in this study. However, clear associations between early-life TL and individual fitness seems difficult to establish and may differ between different populations in the wild.

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Mating strategies and aggressive combat in wingless neotropical fig wasp males

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132008000400013 ◽

2008 ◽

Vol 51 (4) ◽

pp. 553-560 ◽

Cited By ~ 4

Author(s):

Rodrigo Augusto Santinelo Pereira ◽

Angelo Pires do Prado

Keyword(s):

Natural History ◽

Male Competition ◽

Mating Strategies ◽

Encounter Rate ◽

Contest Competition ◽

Fig Wasp ◽

Local Conditions ◽

Wasp Species ◽

Competition Theory ◽

Pollinator Species

The aim of this work was to study the wingless males of pollinating (Pegoscapus tonduzi) and two nonpollinating fig wasp species, genus Idarnes, associated with figs (Ficus citrifolia) in Brazil to answer the following questions: 1) Do wingless males of Idarnes spp. and P. tonduzi show different male-male competition strategies?; and, 2) Do the injury within-species variables correlate with fig/population features? Consistently higher injury levels were observed in the two species of Idarnes than in the pollinator species. The results suggested that aggressive confrontations were involved in the mating strategies of Idarnes, whereas non-aggressive strategies were shown by males of P. tonduzi. Generally, injury variables in Idarnes spp. correlated positively with the male encounter rate and negatively with the fig size, thus supporting the contest competition theory. The results pointed out that different species under similar local conditions might follow distinct evolutionary histories. Within species, natural-history particularities might have some influence upon quantified injury levels in wingless males.

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Eating their cake and having it too: Or, how women maximize reproductive success by simultaneous mating and dating

Behavioral and Brain Sciences ◽

10.1017/s0140525x00313371 ◽

2000 ◽

Vol 23 (4) ◽

pp. 595-595 ◽

Cited By ~ 1

Author(s):

Gwen J. Broude

Keyword(s):

Reproductive Success ◽

Mating Strategies ◽

Short Term ◽

Data Support ◽

Target Article

Data support the claim from the target article that women, both cross-culturally and historically, have employed a variety of mating strategies, marrying but also engaging in short-term unions. But those strategies appear to be practiced simultaneously and not conditionally as Gangestad & Simpson propose, a finding consistent with assumed constraints on the potential reproductive success of females.

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Reproductive biology of Amasonia obovata Gleason (Laminaceae)

Acta Amazonica ◽

10.1590/s0044-59672014000400004 ◽

2014 ◽

Vol 44 (4) ◽

pp. 427-434 ◽

Cited By ~ 1

Author(s):

Thays de Assis Schvinn ◽

Anderson Fernandes de Miranda ◽

Celice Alexandre Silva

Keyword(s):

Reproductive Success ◽

Seed Production ◽

Reproductive Biology ◽

High Frequency ◽

Rainy Season ◽

Mating Strategies ◽

Floral Traits ◽

Mato Grosso ◽

Male And Female ◽

Self Fertilization

Floral mechanisms that ensure seed production via autogamy are more likely to occur in species growing in environments where pollination is scarce. Amasonia obovata was studied in the State of Mato Grosso-Brazil, from 2009 to 2012, to analyze the morphological and reproductive characteristics, aside from investigating the association of the reproductive success with the pollinator frequency and identity. The flowering and fruiting of A. obovata was concentrated in a period of five months during the rainy season. The dichogamy in flowers of A. obovata is not clearly defined, since the sexual functions were overlapped in the male and female phases. The species is self-compatible and not apomictic. The fruiting percentage obtained by hand self-pollination did not differ from cross-breeding (F = 0.74, P =0.39). In the observations from 2010 to 2012, a hummingbird (Thalurania furcata) legitimate visited 20-100% of the flowers in the male and female phases on different A. obovata plants. Due to the high frequency, this hummingbird was considered the single potential pollinator of the species. These findings show that a limited availability of pollinators may select for floral traits and plant mating strategies that lead to a system of self-fertilization.

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The genetic mating system, male reproductive success and lack of selection on male traits in the greater bilby

Australian Journal of Zoology ◽

10.1071/zo09092 ◽

2010 ◽

Vol 58 (2) ◽

pp. 113 ◽

Cited By ~ 4

Author(s):

Emily J. Miller ◽

Mark D. B. Eldridge ◽

Neil Thomas ◽

Nicola Marlow ◽

Catherine A. Herbert

Keyword(s):

Reproductive Success ◽

Mating System ◽

Morphological Traits ◽

Life History Traits ◽

Male Reproductive Success ◽

Home Ranges ◽

Captive Population ◽

Genetic Mating System ◽

Free Ranging ◽

Conservation And Management

The greater bilby (Macrotis lagotis) is the sole remaining species of desert bandicoot on the Australian mainland. The mating system of this species remains poorly understood, due to the bilby’s cryptic nature. We investigated the genetic mating system of the greater bilby in a five-year study of a semi-free-ranging captive population that simulated their wild environment. Morphological traits were examined to determine whether these influenced patterns of male reproductive success and whether selection was acting on them. In any given year more than half the males (59.2 ± 9.3%) failed to sire any offspring. Approximately 70% of sires fathered one offspring, and 30% two or three offspring. Since paternity was not dominated by few males, and given the species’ solitary nature, lack of territoriality and large home ranges, it is likely that males adopt a roving strategy to find receptive females. These results are consistent with an overlap promiscuous mating system. Sires and non-sires could not be distinguished by their morphological traits, and there was no evidence for strong linear or non-linear selection on male traits. These data increase our understanding of bandicoot life-history traits and will assist conservation and management efforts.

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