Operational sex ratio and density predict the potential for sexual selection in the broad-horned beetle

House, Clarissa M.; Rapkin, James; Hunt, John; Hosken, David J.

doi:10.1016/j.anbehav.2019.03.019

Cited by 17 publications

(15 citation statements)

References 56 publications

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“…Future changes in moisture conditions in Alpine areas can be especially concerning because they may affect survival of dung beetles by influencing the sex ratio. Such changes can cause a reduction in mate availability with consequent possible changes in the strength of sexual selection (Kvarnemo & Ahnesjo, 1996; González‐Tokman et al ., 2017; House et al ., 2019).…”

Section: Discussionmentioning

confidence: 99%

Dung beetle resistance to desiccation varies within and among populations

et al. 2021

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The study of desiccation resistance and its underlying traits is key to understanding species responses to changes in water availability, especially in the context of predicted increases in the frequency and severity of droughts due to climate change. We performed laboratory experiments using dung beetles, important ecosystem service providers, to investigate variations in physiological traits within species, both at population and individual levels. Desiccation resistance, water loss tolerance and water content were measured in lowland and mountain populations to investigate whether physiological traits vary (i) according to elevation across four species, and (ii) according to sex or male morphology (minor and major morphs) in two species, and if these responses were consistent across species. Our results showed that desiccation resistance of dung beetles varies both at individual and population levels. We found that desiccation resistance varied between lowland and mountain populations, but no differences were found for other traits such as water loss tolerance. Moreover, differences in individual physiological responses between females, major and minor males suggest that females were more resistant to desiccation than minors and majors, but these responses were species‐dependent. Our analysis at two hierarchical levels, individual and population, emphasizes the importance of considering within‐species variability in predictions of how species may respond to future climatic conditions. Predictions of the responses of species to environmental change may produce different conclusions if they rely on observations from single populations or take into account only a limited range of phenotypes per population.

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Section: Discussionmentioning

confidence: 99%

Dung beetle resistance to desiccation varies within and among populations

et al. 2021

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“…We also anticipated that males with highest numbers of fights per day would have lower mating success, linked to a potential trade-off in energy and time investment between fighting versus mating. However, we predicted that males that more often win fights would gain more matings, given that winning is an attractive trait to females (Gerber et al, 2010; House et al, 2019). Lastly, we expected males to change their investment in fights and matings as the rut progressed, given the energetically costly rut-related activities and the existence of various mating tactics expressed in this species (Ciuti & Apollonio, 2016)…”

Section: Introductionmentioning

confidence: 99%

Delayed benefits for fallow bucks: more fights decrease same day mating success, but may increase matings the next day

Bateman-Neubert

Briefer

McElligott

2022

Preprint

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Dominance hierarchies help to reduce unnecessary fights and associated costs during the mating season. Fallow deer (Dama dama) typically have high levels of male-male competition and strong reproductive skew. Nevertheless, how male dominance and daily fight rates affect mating success remains unknown. We used a two-year dataset from a large population of tagged fallow deer (620-689 individuals), to calculate male dominance ranks based on their agonistic interactions prior to the mating season (‘prerut’), in order to then examine how rank is related to fight rates and mating success during the mating season (‘rut’). Overall, higher-ranked males fought at least twice a day on a higher proportion of days during the rut and secured more matings. Males engaging in more than 10 fights per day were less likely to secure a mating that same day, and those males exceeding 15 fights per day secured no matings at all. Nevertheless, males with the highest numbers of fights (i.e. 15-21 fights per day) on a given day had higher mating success on subsequent days. Although higher-ranked males secured most matings during the rut, their fight rates decreased towards the end. We propose that engaging in more fights negatively affects daily individual mating success, but may benefit mating success on subsequent days, and potentially increase long-term fitness benefits. Additionally, engaging in more fights as the rut progresses probably allows lower-ranked males to secure some matings before the availability of oestrous females ends for almost a year.SIGNIFICANCE STATEMENTFighting carries a risk of injury and high energetic costs. Male fallow deer establish dominance hierarchies, that help reduce unnecessary fights among individuals of different competitive abilities. However, whether high-ranked males fight more or less is yet unknown. By calculating social ranks of fallow bucks before the start of their mating period, we show that males of higher social status do fight and mate more during the mating season (rut). Furthermore, by investigating how investment in fights affects individual mating success that same day and the next day, we find that males that fight more cause a decrease in their immediate daily mating success, but can potentially increase their chances of mating in subsequent days. Thus, to fight more may allow males to climb the hierarchical social ladder, hence increasing longer-term fitness benefits associated to higher ranks.

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“…However, in natural systems, reproductive success is known to be highly dynamic and vary over time (Flanagan et al 2016). Reproductive fluctuations can be affected by ecological variables such as climatic factors (McAllan andGeiser 2006, Wacker et al 2014), the distribution and availability of nest sites/territories (Forsgren et al 1996), variation in mate quality (Kvarnemo and Forsgren 2000), the density of individuals (Eshel 1979, House et al 2019, or by the operational sex ratio (OSR) (Reichard et al 2008, Wong et al 2018. Throughout a breeding season, changes in such variables can cause fluctuations in the intensity and strength of sexual selection and can also interact to affect mate choice or mate quality (Reichard et al 2008, Milner et al 2010, Flanagan et al 2016.…”

Section: Introductionmentioning

confidence: 99%

“…showing that males compete more in male-biased OSRs and in some cases have increased their display of courtship behaviours (Forsgren et al 2004, Carrillo et al 2012, Aronsen et al 2013, Wacker et al 2013. Within-season change in the OSR is predominantly caused by changes in the density of individuals (House et al 2019). Population density is predicted to influence reproductive success by altering mate availability and competition (Eshel 1979, Forsgren et al 2004, House et al 2019.…”

Section: Introductionmentioning

confidence: 99%

“…Within-season change in the OSR is predominantly caused by changes in the density of individuals (House et al 2019). Population density is predicted to influence reproductive success by altering mate availability and competition (Eshel 1979, Forsgren et al 2004, House et al 2019. At high densities, individuals may be able to monopolize matings and female choosiness may increase due to a greater variance in male quality and increased intersexual encounter rates (Zeh 1987, Owens and Thompson 1994, Borg et al 2006.…”

Section: Introductionmentioning

confidence: 99%

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Disentangling the determinants of reproductive success in a temperate reef fish, Forsterygion lapillum

Tornquist¹

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<p>Identifying sources of individual variation in reproductive success has been a longstanding challenge for evolutionary ecologists. Reproductive success among individuals can be due to several factors such as competition between conspecifics for nest sites and mating partners, mate choice, or by the physical environment. Reproductive success, particularly among males, can be extremely diverse both within and between species and determining which components contribute to success can be particularly challenging. In this thesis, I investigated patterns and drivers of reproductive success in a temperate marine reef fish, Forsterygion lapillum (the common triplefin). Specifically, I examined how male quality, nest quality, and female choice influence male reproductive success. Additionally, I quantified male reproductive success during the winter and summer of the breeding season to examine the temporal dynamics of breeding success in F. lapillum. Selection of mates by females can be driven by the quality and behavioural attributes of the male or by the quality of resources offered. In Chapter 2, using field-based observations, combined with a lab-based study, I evaluated the effects of different male traits and nest characteristics on female choice and male reproductive success. Specifically, I observed egg guarding males in the field during the breeding season and recorded their phenotypic traits, behaviours, and nest characteristics. I then examined their influence on 3 different components of male reproductive success (brood size, individual egg size, and mate attraction). Additionally, I conducted dichotomous choice tests in the laboratory to evaluate female preference for different sized males, holding different sized nests. In the field, I did not detect a significant relationship between male mating success and male total length or nest size. Brood size and individual egg size were highly variable among sampled males, however, further factors such as courtship frequency, and the number of interactions with potential predators did not explain any additional variation. The number of agonistic displays performed by egg guarding males was the only factor to influence egg size, however, it had no direct impact on brood size or mate attraction. On the contrary, results from the laboratory experiment suggested that male total length and nest size were important during female choice. Females were attracted to and spawned more frequently with larger males holding larger nests. Additionally, females showed a particular preference towards males that displayed intense courtship behaviours. These results suggest that variation in reproductive success among individuals is not random in the common triplefin (F. lapillum) and may be due to a range of complex factors. In natural systems, individual variation in mating success is known to be highly dynamic and vary over time. In Chapter 3, I addressed 3 questions related to reproductive success in male common triplefin: 1) Does the operational sex ratio (OSR) and the density of individuals change predictably within the breeding season? 2) Does male reproductive success change within the breeding season? And 3) Does the age and growth rate of successful males change within the breeding season? To address these questions, I sampled a population of F. lapillum during two periods of the breeding season and quantified a set of morphological and physical traits. Furthermore, I reconstructed individual life histories from the otoliths of egg guarding males. My results show that the density of individuals in the population increased during the summer months, but the operational sex ratio (OSR) remained male-biased. Male reproductive success in terms of brood size and average egg size did not fluctuate during the sampling period. However, the size of males and the size of the nest (cobblestone) held by males was significantly larger in summer compared to winter. Interestingly, successful males sampled in the winter had hatched significantly earlier than successful males sampled in the summer, but their average growth rate remained similar. These findings indicate that variation in male traits across the breeding season plays an important role in female mate choice. The mating system and pool of mating individuals in the common triplefin (F. lapillum) is highly dynamic over the year and has the potential to shape the success of individuals. Overall, this study emphasizes the importance of considering multiple cues and temporal dynamics when disentangling the determinants of individual reproductive success. These findings suggest that male-male competition and female mate choice have a significant influence on male reproductive success. The reproductive ecology of F. lapillum is highly complex and my research has provided valuable insight into its dynamic nature. These results may apply to other species with male parental care and provides an important contribution towards understanding sexual selection and the evolution of mating systems with male parental care.</p>

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Operational sex ratio and density predict the potential for sexual selection in the broad-horned beetle

Cited by 17 publications

References 56 publications

Dung beetle resistance to desiccation varies within and among populations

Dung beetle resistance to desiccation varies within and among populations

Delayed benefits for fallow bucks: more fights decrease same day mating success, but may increase matings the next day

Disentangling the determinants of reproductive success in a temperate reef fish, Forsterygion lapillum

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