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Thomas H. Kunz - One of the best experts on this subject based on the ideXlab platform.
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The economics of Harem maintenance in the sac-winged bat, Saccopteryx bilineata (Emballonuridae)
Behavioral Ecology and Sociobiology, 2001Co-Authors: Christian C. Voigt, Otto Von Helversen, Robert H. Michener, Thomas H. KunzAbstract:Saccopteryx bilineata has a polygynous mating system in which males defend females in a Harem territory. Harem defense and courtship include energetically costly flight maneuvers and hovering displays. We tested if (1) Harem males have a greater field metabolic rate than non-Harem males or females and if (2) the field metabolic rate of Harem males is correlated with the number of females in a Harem territory. We measured the energy budget in 32 S. bilineata with the doubly labeled water method and compared these estimates with behavioral observations in the daytime roost. Among adult bats, field metabolic rate varied with body mass by an exponent of approximately two. We found no significant difference in field metabolic rate or mass-specific field metabolic rate between Harem and non-Harem males. The mass-specific field metabolic rate of Harem-males increased with Harem size. The latter finding supports the hypothesis that the energy costs of courtship display and territorial defense influence the energy budget of Harem males. Overall, field metabolic rates of S. bilineata were lower than those of similarly sized bats of the temperate zone and only 2.3 times above the basal metabolic rate recorded for this species. We suggest that male S. bilineata did not take advantage of their metabolic capacity because a prudent allocation of energy to activities of Harem maintenance is an adaptive strategy for males in this mating system.
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social structure of a polygynous tent making bat cynopterus sphinx megachiroptera
Journal of Zoology, 2000Co-Authors: Jay F Storz, Hari R Bhat, Thomas H. KunzAbstract:The social structure of an Old World tent-making bat Cynopterus sphinx (Megachiroptera), was investigated in western India. A combination of census and mark–recapture data over 2 years (1996–98) was used to infer the form of the mating system, compositional stability of social groups and mode of new social group formation. The breeding population of C. sphinx was subdivided into diurnal roosting colonies, each of which contained one to five discrete roosting groups and often one or more solitary bats in adjacent roosts. Bats most frequently roosted in stem tents constructed in the flower/fruit clusters of the kitul palm Caryota urens. Temporal variation in social structure was assessed using visual census data for a subset of the study population over 3 years (1995–98) spanning six consecutive reproductive periods. The sex and age composition of diurnal roosting groups indicated a polygynous Harem-forming mode of social organization, as groups invariably contained a single adult male, 1–37 reproductive females and their dependent young (n= 33 Harems). Harem size averaged 6.1 adults in the wet season (n= 19, sd= 3.5) and 13.6 adults in the dry season (n= 14, sd= 8.5). The same Harem social configuration was maintained year-round, despite a high degree of synchrony and seasonality in the timing of reproduction. Juveniles of both sexes dispersed after weaning and sexually immature bats were never present in Harems at the time of parturition. Adult females often remained associated as roostmates from one parturition period to the next, and group cohesion was unaffected by turnover of Harem males. Adult females frequently transferred among roosts within the same colony, and Harems underwent periodic fissions and fusions. The founding of new Harems most often resulted from the fissioning of previously cohesive Harems within the same colony. However, some Harems contained disproportionate numbers of yearling females, indicating that new groups are also founded by nulliparous females of the same age cohort. A significant degree of heterogeneity in age composition among Harems was revealed in the 1998 dry season, but was unrelated to age-stratification of tent roosts. Although formation of new Harems may be non-random with respect to age composition of the founders, founding events are not restricted to newly created tents and often involve recolonization of previously occupied roosts.
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dispersion and site fidelity in a tent roosting population of the short nosed fruit bat cynopterus sphinx in southern india
Journal of Tropical Ecology, 2000Co-Authors: Jay F Storz, J Balasingh, Thiruchenthil P Nathan, K Emmanuel, Thomas H. KunzAbstract:Patterns of dispersion and site fidelity were investigated in a tent- roosting population of the short-nosed fruit bat, Cynopterus sphinx (Megachiroptera), in southern India. A local population of C. sphinx occupied diurnal roosts in a variable subset of 45 stem tents constructed within the dense foliage of mast trees (Polyalthia longifolia). Individually marked tent-roosting bats were visually censused over the course of a 38-d interval spanning the postpartum oestrus period. On any given day, 33.3-85.7% (mean = 60.8%, SD = 14.2) of adult males roosted singly, with the remainder holding Harems of 1-10 breeding females (mean = 3.01, SD = 0.79). Average Harem sex ratio was 2.8-fold higher than the adult sex ratio of the total tent-roosting population within the study area, indicat- ing the potential for a high variance in male mating success within a single breed- ing season. Bats of both sexes typically occupied one primary tent, interspersed with shorter periods of residency in alternate tents. Males exhibited a significantly higher degree of roost fidelity than females. Some females roosted sequentially with different males and with different combinations of females, whereas others remained continuously associated with a single male and/or particular female roostmates over the duration of the census period. There were no statistically significant relationships between physical characteristics of tents and rates of occupancy by males or females. Intermittent transfers by females between groups suggest that the defence of diurnal roosts by males represents a more profi- table mating strategy than the direct defence of compositionally labile female groups.
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Economy of Harem Maintenance in the Greater Spear-Nosed Bat, Phyllostomus hastatus
Journal of Mammalogy, 1998Co-Authors: Thomas H. Kunz, Simon K.a. Robson, Kenneth A. NagyAbstract:To investigate constraints on males associated with maintenance of Harems, we used a time-energy approach to explore the relationship between temporal occupancy of roosts and nightly foraging activity in male and female greater spear-nosed bats, Phyllostomus hastatus. Harem males and females differed significantly in frequency and duration of nightly foraging bouts. Harem males spent less time away from their roost at night and departed and returned more frequently than did other members of the Harem. Adult females and one subadult male foraged mostly during the first 2-3 h after sunset. Total time spent foraging by Harem males, adult females, and a subadult male, averaged 98, 152, and 115 min per night, respectively. On average, Harem males engaged in 7.2 randomly spaced foraging bouts per night, compared with 2.1 bouts for Harem females and 2.0 bouts for a subadult male. Field metabolic rate, expressed on a mass-specific basis (ml CO2 g-1 h-1), averaged 3.4 ± 0.69 SD for Harem males, 3.0 ± 0.85 for adult females, 1.9 ± 0.08 for a subadult male. These values varied predictably but did not differ significantly. Similarly, daily energetic expenditure, expressed on a whole-animal basis (kJ/day), averaged 168.6 ± 32.5 for Harem males and 124.9 ± 38.9 for adult females but did not differ significantly. Because Harem males allocate less time to nightly foraging activity compared with adult females, males should have more time and energy available for vigilance at the roost and/or the defense of females.
Justin A. Welbergen - One of the best experts on this subject based on the ideXlab platform.
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Testosterone is associated with Harem maintenance ability in free-ranging grey-headed flying-foxes, Pteropus poliocephalus.
Biology Letters, 2009Co-Authors: Stefan M. Klose, Justin A. Welbergen, Elisabeth K V KalkoAbstract:Males of many vertebrate species aggressively defend their reproductive interests by monopolizing females, and the ‘challenge hypothesis’ predicts that testosterone levels in reproductive contexts rise to facilitate males' competitive behaviours necessary for meeting social challenges. The hypothesis is successful in explaining patterns of testosterone secretion in many avian species, but remains comparatively unexplored in mammals. ‘Circulating plasma testosterone levels (T)’ were studied in relation to Harem maintenance in grey-headed flying-foxes, Pteropus poliocephalus. In this species, Harems provide mating opportunities and so a male's ability to maintain a Harem is likely to correlate with his fitness. We hypothesized that if T reflect a male's ability to withstand challenges from competitors, then T should be linked to successful Harem maintenance. To test this, we temporarily removed males from their territories prior to and during the short mating period, recording their Harem sizes both before removal and after reintroduction. Most males successfully reclaimed their territory and a Harem, but during the mating period, males with higher T had Harems closer to their original size, and males with lower T suffered reduction in Harem size. Our findings highlight the role of T in Harem maintenance in a major mammalian taxon with complex forms of social organization.
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timing of the evening emergence from day roosts of the grey headed flying fox pteropus poliocephalus the effects of predation risk foraging needs and social context
Behavioral Ecology and Sociobiology, 2006Co-Authors: Justin A. WelbergenAbstract:This study addresses the functional question of how variation in foraging strategy, predation risk, and social context influence the timing of the evening emergence from day roosts of the grey-headed flying fox, Pteropus poliocephalus. The onset of evening emergence was expected to vary according to the relative costs and benefits of emerging early and should, therefore, reflect an optimal trade-off between predation risks and foraging needs. The onset of the colony-wide emergence was closely correlated with the time of sunset and cloud cover. However, as expected, the onset of the colony-wide emergence was delayed when a diurnal avian predator was present, whereas the onset was advanced during lactation when presumably energetic demands are higher. The trade-off between predation risks and foraging needs was further reflected in the emergence times of individual bats: adult females emerged earlier when they had higher foraging needs as indicated by their body condition; young emerged later when they were smaller and likely to be more at risk from predation due to their less developed flying skills. However, the emergence time of adult males depended on their social status: smaller bachelor males emerged from the colony earlier than larger Harem-holding males who guard their Harems until the last female had left. Thus, whereas the colony-wide emergence time reflected the outcome of a trade-off between predation risks and general foraging needs, on an individual level, the outcome of this trade-off depended on sex, age, body condition, and structural size and was modified by social context.
Christian C. Voigt - One of the best experts on this subject based on the ideXlab platform.
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male greater sac winged bats gain direct fitness benefits when roosting in multimale colonies
Behavioral Ecology, 2012Co-Authors: Christian C. Voigt, Martina Nagy, Mirjam Knornschild, Frieder MayerAbstract:Social groups that are characterized by the presence of male kin are rare in mammals. Theory predicts that males reproducing in such groups need to overcome the costs of local mate competition, which are supposedly severe in polygynous or promiscuous mating systems. Here, we studied in a polygynous mammal with male philopatry whether male group size renders direct fitness benefits for males that could outweigh the costs of competing with related males for access to territories and mates. We used long-term behavioral observations and genetic data of the greater sac-winged bat to investigate the factors affecting lifetime breeding success (LBS) of Harem males living in colonies that contain varying numbers of male residents. We show that tenure of Harem males increased with the number of male coresidents and that Harem male tenure explained a large proportion of variation in their LBS. Thus, our results provide evidence that males gain direct fitness benefits from a social organization in colonies that include additional Harem territories and nonHarem males. Immigration of males into colonies was significantly lower when nonHarem males (young males that are often related to Harem males) were permanently present in colonies, suggesting that larger male groups may be better able to maintain a patriline in a colony and thus also ensure future indirect fitness benefits. Key words: female-biased dispersal, lifetime breeding success, male tenure, Saccopteryx bilineata, social organization. [Behav Ecol]
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queuing for Harem access in colonies of the greater sac winged bat
Animal Behaviour, 2003Co-Authors: Christian C. Voigt, W J StreichAbstract:Colonies of the greater sac-winged bat, Saccopteryx bilineata, consist of nonterritorial males and males that defend Harem territories in which females roost. The traits of nonterritorial males that define their success in Harem take-overs are so far unknown. We predicted that the time nonterritorial males spent in the colony and their proximity to Harems would be important factors. We temporarily removed Harem holders from a colony of 60 greater sac-winged bats on consecutive days and observed which of the nonterritorial males took over the Harem. To test for consistency of results, we repeated the experiments in some of the territories. In a second set of experiments, we removed both the Harem holder and the corresponding usurper from the first experiment. On average, usurping males preferred territories with a large Harem over territories with a small Harem and they belonged to groups of males who spent the daytime near the corresponding Harems. Usurpers in the second experiment were present in the colony for a shorter time than usurpers in the first experiment. Overall, the results support the hypothesis that nonterritorial males form overlapping peripheral groups for Harems and that they live in a hierarchy according to their tenure in the group. Group membership and hierarchy seemed to be the factors that determined whether a male occupied a vacant Harem. Hence, instead of floating, the pattern of Harem succession in greater sac-winged bats is best described by queuing of nonterritorial males for access to a Harem.
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The economics of Harem maintenance in the sac-winged bat, Saccopteryx bilineata (Emballonuridae)
Behavioral Ecology and Sociobiology, 2001Co-Authors: Christian C. Voigt, Otto Von Helversen, Robert H. Michener, Thomas H. KunzAbstract:Saccopteryx bilineata has a polygynous mating system in which males defend females in a Harem territory. Harem defense and courtship include energetically costly flight maneuvers and hovering displays. We tested if (1) Harem males have a greater field metabolic rate than non-Harem males or females and if (2) the field metabolic rate of Harem males is correlated with the number of females in a Harem territory. We measured the energy budget in 32 S. bilineata with the doubly labeled water method and compared these estimates with behavioral observations in the daytime roost. Among adult bats, field metabolic rate varied with body mass by an exponent of approximately two. We found no significant difference in field metabolic rate or mass-specific field metabolic rate between Harem and non-Harem males. The mass-specific field metabolic rate of Harem-males increased with Harem size. The latter finding supports the hypothesis that the energy costs of courtship display and territorial defense influence the energy budget of Harem males. Overall, field metabolic rates of S. bilineata were lower than those of similarly sized bats of the temperate zone and only 2.3 times above the basal metabolic rate recorded for this species. We suggest that male S. bilineata did not take advantage of their metabolic capacity because a prudent allocation of energy to activities of Harem maintenance is an adaptive strategy for males in this mating system.
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extra Harem paternity in the white lined bat saccopteryx bilineata emballonuridae
Behaviour, 1999Co-Authors: Otto Von Helversen, Christian C. Voigt, Frieder Mayer, Gerald HeckelAbstract:We studied the paternity in a colony of the Harem-polygynous white-lined bat Saccopteryx bilineata by microsatellite typing and compared the data with group composition and stability. Although we recorded a high stability for Harem groups, neither spatial proximity of males to Harem females nor Harem ownership allowed us to predict the paternity of the next year's Harem offspring. Eight out of 28 juveniles were fathered by holders of the Harem in which they were born, while the other 20 represent Extra-Harem-Young (EHY). 50% of EHY were fathered by males from outside the colony and 50% by other Harem holders or peripheral males of the colony. On average, reproductive success of Harem holders (1.2 offspring/year) was higher compared with peripheral males (0.4 offspring/year). Harem size seemed not to influence reproductive success of Harem holders. Although maintaining of a territory seems to be costly for a Harem male, his ability to control the females of his Harem may be restricted; instead female Saccopteryx bilineata appear to have a high potential for female choice.
Jorge Ortega - One of the best experts on this subject based on the ideXlab platform.
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Aggression and tolerance by dominant males of Artibeus jamaicensis: Strategies to maximize fitness in Harem groups
Journal of Mammalogy, 2008Co-Authors: Jorge Ortega, José Antonio Guerrero, Jesus E MaldonadoAbstract:Strategies of males in Harem-forming mammals may change depending on 2 variables, female group size and consequent ability of the Harem male to monopolize copulations, and the relative costs and benefits of tolerating other males. We studied Harems of 4–20 females associated with a dominant male in small groups of Artibeus jamaicensis ( 14 females). Dominant males displayed defensive behavior toward satellite males when they intruded into the roosting site. Small groups received the highest number of visits by satellite males, and dominant males did not display total defense of females. During the breeding season, females roosted in highly compacted clusters and dominant males were more active in their defensive behavior. Subordinate males were generally tolerated in Harem groups and their presence reduced the number of adult male visits. Some young in large Harem groups were sired by subordinate males, resulting in a genetic benefit for both dominant and subordinate males. Dominant males had the highest fitness in the large Harem groups by sharing paternity with related subordinate males and by rejecting unrelated intruders.
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Female interactions in Harem groups of the Jamaican fruit-eating bat, Artibeus jamaicensis (Chiroptera: Phyllostomidae)
Acta Chiropterologica, 2006Co-Authors: Jorge Ortega, Jesus E MaldonadoAbstract:ABSTRACT Harem groups of the Jamaican fruit-eating bat (Artibeus jamaicensis) are well-defined units that occupy different crevices in caves. For two consecutive years, we analyzed the non-random associations among female bats and their interactions with other members of the Harem. Female members occupying the edges of the Harems came from different parts of the cave and were more frequently expelled from the roosting site. Females from the central core of the Harem were attacked less often and received more affiliative interactions. Females occupying areas between the central core and the edges were the most active in repelling arriving females and were responsible for grooming the central core females. During the breeding season, aggressive activities decreased and females became more tolerant, which suggests that a potential benefit of roosting together is that it provides for a more suitable place to nurse newborns, because all females produce a better environment, in thermoregulatory ways.
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male dominance paternity and relatedness in the jamaican fruit eating bat artibeus jamaicensis
Molecular Ecology, 2003Co-Authors: Jorge Ortega, Hector T Arita, Jesus E Maldonado, Gerald S Wilkinson, Robert C FleischerAbstract:We analysed variation at 14 nuclear microsatellite loci to assess the genetic structure, relatedness, and paternity of polygynous Jamaican fruit-eating bats. A total of 84 adults captured in two caves exhibited little genetic differentiation between caves ( F ST = 0.008). Average relatedness among adult females in 10 Harem groups was very low ( R = 0.014 ± ± ± 0.011), providing no evidence of Harem structure. Dominant and subordinate males shared paternity in large groups, while dominant and satellite males shared paternity in smaller groups. However, our results suggest that male rank influences paternity. Dominant males fathered 69% of 40 offspring, followed by satellite (22%) and subordinate males (9%). Overall adult male bats are not closely related, however, in large Harem groups we found that subordinate and dominant males exhibited relatedness values consistent with a father-offspring relationship. Because dominant and subordinate males also sired all the pups in large groups, we propose that their association provides inclusive fitness to them.
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subordinate males in Harem groups of jamaican fruit eating bats artibeus jamaicensis satellites or sneaks
Ethology, 2002Co-Authors: Jorge Ortega, Hector T AritaAbstract:In the caves of Yucatan, Mexico, the Jamaican fruit-eating bat, Artibeus jamaicensis, forms Harems consisting of four to 18females and a dominant male that defends the group against foreign males. Large groups (>14 females) contain an additional subordinate male. In theory, subordinate males can associate with Harem groups either as satellites, if they provide at least some benefits to the dominant male, or as sneaks, if they only impose costs on the dominant male. We assessed the costs and benefits of subordinate males in three removal experiments. In the first experiment, when a dominant male was removed from its group, its role was occupied by the subordinate male (in large groups) or by a foreign male (in small groups). Former subordinate males took less time to gain control of the Harems and stayed longer with the groups than foreign males. In the second experiment, when a subordinate male was removed, the rate of visitation by foreign males and the number of agonistic displays by the dominant male both increased. In the third experiment, when the number of females in large groups was reduced, subordinate males spent less time with their groups and the rate of visitation by foreign males increased. However, the frequency of agonistic displays by dominant males towards subordinate males did not change. Dominant males invest large amounts of energy in defending the Harems, but obtain direct and immediate benefits from the presence of subordinate males in the form of access to a larger number of females, and suffer no obvious costs. Subordinate males apparently invest little energy in defending the Harems, obtain no obvious immediate benefit, but gain long-term benefits by having priority access to vacant positions left by dominant males. Subordinate males in Harem groups of the Jamaican fruit-eating bat can be considered satellites because their presence brings immediate benefits to the dominant males.
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Structure and Social Dynamics of Harem Groups in Artibeus jamaicensis (Chiroptera: Phyllostomidae)
Journal of Mammalogy, 1999Co-Authors: Jorge Ortega, Hector T AritaAbstract:The Jamaican fruit-eating bat ( Artibeus jamaicensis ) is one of the most common Neotropical chiropterans, but comparatively little is known about structure and dynamics of its social groups. In two caves of the Yucatan Peninsula, Mexico, we found Jamaican fruiteating bats forming Harem groups, consisting of 4–18 females and 1–2 males, inside solution cavities that develop on the ceiling of caves. Other individuals roosted solitarily in the same caves, but outside solution cavities. We identified three types of males: dominants (one in each Harem group), subordinates (present only in the largest Harems), and satellites (not associated with a Harem). Dominants were larger and heavier than males of the other two categories. During the 2-year study, Harem groups always roosted in the same cavity and presented a high degree of stability, with few changes in composition. Satellite males and solitary females, in contrast, shifted roosting sites frequently and never formed cohesive groups. Adult females performed more movements from and to Harem groups than males, and those movements were less frequent during the breeding season. Harems of the Jamaican fruit-eating bat presented subordinate males in large groups and differ from those of other phyllostomids in the lower degree of cohesiveness shown by females.
Nicolas Fasel - One of the best experts on this subject based on the ideXlab platform.
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alternative reproductive tactics sperm mobility and oxidative stress in carollia perspicillata seba s short tailed bat
Behavioral Ecology and Sociobiology, 2017Co-Authors: Charlotte Wesseling, Nicolas Fasel, Fabrice Helfenstein, Gaétan Glauser, Armelle Vallat, Ahana Aurora Fernandez, Heinz RichnerAbstract:In social systems with alternative reproductive tactics, sneakers face a higher level of sperm competition than Harem males and hence are predicted to allocate more resources to ejaculates. Antioxidants can protect sperm against oxidative stress, and thus, their allocation to the ejaculate may depend on mating tactic. In this study on the frugivorous bat Carollia perspicillata, we assessed, for Harem and sneaker males, four sperm mobility traits, blood and ejaculate markers of the redox balance and the ejaculate to blood ratios of the redox markers. Under higher sperm competition, sneaker males should allocate proportionally more antioxidant resources to the protection of sperm than Harem males. In contrast, Harem males should favour pre-copulatory functions, which comprise the protection of blood. We found significantly higher sperm velocity and sperm survival in sneakers. There was no correlation between sperm mobility and sperm enzymatic antioxidant activity or ejaculate levels of lipid peroxidation (oxidative damage). Ejaculate levels of lipid peroxidation and sperm survival showed a significantly positive correlation, which could be attributed to the role of reactive oxygen species for sperm capacitation. Harem and sneaker males showed similar levels of redox balance markers in ejaculate and blood. However, Harem males showed a higher ratio of oxidized over reduced glutathione in blood, which may indicate higher cellular stress due to higher metabolism. Overall, our findings suggest that sneakers of C. perspicillata compensate for a higher level of sperm competition by higher sperm mobility. In social systems with alternative reproductive tactics, sneakers face higher level of sperm competition than Harem males and hence are predicted to allocate more resources to ejaculates. Antioxidants can protect sperm against oxidative stress, and thus, their allocation to the ejaculate may depend on mating tactic. In this study on the frugivorous bat Carollia perspicillata, we found sperm swimming significantly faster and longer in sneaker males compared to Harem males. However, traits other than the investigated antioxidant may favour higher sperm mobility. Measured redox pattern in blood of Harem males may indicate higher cellular stress due to higher metabolism. Our results provide support to the current sperm competition models at the intraspecific level, which is still debated for internal fertilizers. This study contributes to better understanding the trade-offs and adaptations resulting from alternative reproductive tactics in mammals.
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Alternative reproductive tactics and reproductive success in male Carollia perspicillata (Seba's short-tailed bat).
Journal of evolutionary biology, 2016Co-Authors: Nicolas Fasel, Verena Saladin, Heinz RichnerAbstract:The use of alternative reproductive tactics (ARTs) is widespread in animals. Males of some species may change tactics depending on age, body condition and social environment. Many bat species are polygynous where a fraction of males only have access to fertile females. For polygynous bats, knowledge of the reproductive success of males using different ARTs is scarce, and it remains unclear how age of males is related to switching decisions between social statuses. We studied a large captive population of Carollia perspicillata, where males are either Harem holders, bachelors or peripheral males. Using a multistate procedure, we modelled the age-related switches in reproductive tactics and in survival probability. From the model, we calculated the reproductive success and the frequencies of males displaying different reproductive tactics. As in mammals, the switch between social statuses is often related to age, we predicted that the transition probability of bachelor and peripheral males to Harem status would increase with age. We show, however, that social status transition towards a Harem holding position was not related to age. Reproductive success changed with age and social status. Harem males had a significantly higher reproductive success than bachelor males except between a short period from 3.8 to 4.4 years of age where success was similar, and a significantly higher reproductive success than peripheral males between 2.6 and 4.4 years of age. Harem males showed a clear decrease in the probability of maintaining social status with age, which suggests that senescence reduces resource holding potential.
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Modification of sperm quality after sexual abstinence in Seba's short-tailed bat, Carollia perspicillata
The Journal of Experimental Biology, 2016Co-Authors: Charlotte Wesseling, Nicolas Fasel, Heinz Richner, Fabrice HelfensteinAbstract:ABSTRACT In polygynous mating systems, few males have stable access to sexual mates. With an expected higher copulation rate, Harem males may deplete seminal fluids or increase epididymal sperm maturation, generating poor sperm quality. In a first study, we reported a higher sperm quality in sneaker males of Carollia perspicillata . To test whether the lower sperm quality observed in Harem males was generated by an elevated copulation rate, we temporarily removed males of both social statuses from the colony. We thus assessed status-related changes of sperm quality resulting from sexual abstinence. Moreover, released from territory and female guarding, Harem males were expected to show a reduction in somatic costs. On the basis of sperm competition models, we predicted a higher resource investment in the ejaculate with the reduction of pre-copulatory efforts. In line with our predictions, sperm quality of Harem males improved significantly in contrast to sneaker males, whose sperm quality did not change. Without an increase in ejaculate lipid peroxidation, our results also provide evidence that the duration of sexual abstinence was not sufficient to generate sperm oxidative damage through senescence. Harem males did not show a reduction in blood lipid peroxidation or in the ratio of oxidized to reduced glutathione. In line with the maintenance of these somatic costs, Harem males did not invest more superoxide dismutase to the ejaculate to maintain sperm quality. Our results suggest that a difference in copulation rate rather than an adaptation to sperm competition provides sneaker males with higher sperm quality in C. perspicillata .
