Selection For Large Body Size Research Articles

Fat storage influences fasting endurance more than body size in an ungulate

Abstract The fasting endurance hypothesis (FEH) predicts strong selection for large body size in mammals living in environments where food supply is interrupted over prolonged periods of time. The Arctic is a highly seasonal and food‐restricted environment, but contrary to predictions from the FEH, empirical evidence shows that Arctic mammals are often smaller than their temperate conspecifics. Intraspecific studies integrating physiology and behaviour of different‐sized individuals may shed light on this paradox. We tested the FEH in free‐living Svalbard reindeer Rangifer tarandus platyrhynchus. We measured daily energy expenditure (DEE), subcutaneous body temperature (Tsc) and activity levels during the late winter in 14 adult females with body masses ranging from 46.3 to 57.8 kg. Winter energy expenditure (WEE) and fasting endurance (FE) were modelled dynamically by combining these data with body composition measurements of culled individuals at the onset of winter (14 years, n = 140) and variation in activity level throughout winter (10 years, n = 70). Mean DEE was 6.3 ± 0.7 MJ/day. Lean mass, Tsc and activity had significantly positive effects on DEE. Across all 140 individuals, mean FE was 85 ± 17 days (range 48–137 days). In contrast to the predictions of the FEH, the dominant factor affecting FE was initial fat mass, while body mass and FE were not correlated. Furthermore, lean mass and fat mass were not correlated. FE was on average 80% (45 days) longer in fat than lean individuals of the same size. Reducing activity levels by ~16% or Tsc by ~5% increased FE by 7% and 4% respectively. Our results fail to support the FEH. Rather, we demonstrate that (a) the size of fat reserves can be independent of lean mass and body size within a species, (b) ecological and environmental variation influence FE via their effects on body composition and (c) physiological and behavioural adjustments can improve FE within individuals. Altogether, our results suggest that there is a selection in Svalbard reindeer to accumulate body fat, rather than to grow structurally large. A free Plain Language Summary can be found within the Supporting Information of this article.

Motorway age is linked to larger body size, but not song carrier frequency, in male grasshoppers from roadside populations

Producing calls with increased minimum carrier frequency is well documented in sound communicating species confronted with noise pollution, possibly helping them to avoid acoustic masking of low-frequency signals. However, the lack of studies on invertebrates limits our understanding of the potentially adverse effects of anthropogenic noise on natural populations. While males of the grasshopper Chorthippus biguttulus are known to produce courtship signals with elevated low-frequency local maxima (LFLM) in roadside populations, previous studies provided no insight into morphological traits underlying LFLM shifts. Although developmental plasticity was identified as one main factor accounting for elevated LFLM, an additional role for a more hard-wired trait architecture was proposed, possibly as a result of adaptation to traffic noise. Our current study therefore aims to assess (1) whether the position of LFLM is related to male body size, (2) whether body size is correlated with motorway age, and (3) whether the position of LFLM is correlated with motorway age in C. biguttulus males from roadside populations. In addition to substantial variation in LFLM among C. biguttulus males, we found that larger males produced signals with lower LFLM, suggesting a potential role in female choice as a predictor of male quality. While we found no significant correlation between LFLM and motorway age, C. biguttulus males were larger near older motorway sections. This positive correlation may be due to several reasons, including: (1) higher nutrient concentration and availability in plant tissues due to eutrophication of roadside habitats; (2) temporal succession of male size phenotypes during colonization processes; and/or (3) selection for larger body size in roadside populations. Our results highlight the multifaceted and often complex nature of the relationships between morphology, signal traits and anthropogenic pressures on sound communication in invertebrates.

Bergmann's rule is followed at multiple stages of postembryonic development in a long-distance migratory songbird.

Bergmann’s rule is a well‐established, ecogeographical principle that states that body size varies positively with latitude, reflecting the thermoregulatory benefits of larger bodies as temperatures decline. However, this principle does not seem to easily apply to migratory species that are able to avoid the extreme temperatures during winter at higher latitudes. Further, little is known about the ontogeny of this relationship across life stages or how it is influenced by ongoing global climate change. To address these knowledge gaps, we assessed the contemporary relationship between latitude and body size in a long‐distance migratory species, the prothonotary warbler (Protonotaria citrea) across life stages (egg to adult) on their breeding grounds. We also measured historic eggs (1865‐1961) to assess if the relationship between latitude and size during this life stage has changed over time. In accordance with Bergmann’s rule, we found a positive relationship between latitude and body mass during all post‐embryonic life stages, from early nestling stage through adulthood. We observed this same predicted pattern with historic eggs, but contemporary eggs exhibited the reverse (negative) relationship. We suggest that these results indicate a genetic component to this pattern and speculate that selection for larger body size in altricial nestlings as latitude increases may possibly drive the pattern in migratory species as even rare extreme cold weather events may cause mortality during early life stages. Furthermore, the opposite relationships observed in eggs, dependent on time period, may be related to the rapidly warming environments of higher latitudes that is associated with climate change. Although it is unclear what mechanism(s) would allow for this recent reversal in eggs (but still allow for its maintenance in later life stages). This evidence of a reversal suggests that anthropogenic climate change may be in the process of altering one of the longest‐standing principles in ecology.

Does sexual dimorphism vary by population? Laryngeal and ear anatomy in cricket frogs.

Acoustic communication in many anuran species can show the effects of both natural and sexual selection. This is reflected in the sexually dimorphic anatomy of the larynx and ear structures, as well as the allometric relationship of these morphological traits to head or body size. In this study, we examined laryngeal and ear structures of cricket frogs Acris crepitans not only as sexually dimorphic characteristics, but also as they differ across populations in environmentally different habitats. We used 2-way ANOVA to determine whether the volumetric or linear measurements of these structures differed by sex and population. Females have significantly larger body, head, and ear sizes, but significantly smaller larynges than males. Furthermore, females as well as males show larger body and head sizes, ears, and larynges in a dryer open habitat. An ANCOVA analysis shows that males, but not females, differ in laryngeal size across populations beyond the allometric changes attributable to head size alone indicating that males have a greater degree of laryngeal population variation. In contrast, our covariate analysis found that in both sexes many of the ear differences are non-significant once head size is accounted for, suggesting that most of the population-level ear variation is due to allometric effects of body size. We conclude that although both sexes show size differences in the larynx related to selection for larger body size in dry, open habitats, selection on males for larger larynx size related to the production of lower frequency calls in those habitats does not result in correlated changes in the female larynx. The results suggest that in anurans, selection for changes in body and head size affects both sexes equally, male calls and the vocal structures responsible for them can further diversify without concordant changes in females.

Clinal variation in avian body size is better explained by summer maximum temperatures during development than by cold winter temperatures

ABSTRACT Across many taxa, clinal variation in body size has been observed to follow Bergmann's rule, which predicts larger body size in colder climates. For more than a century, this pattern has typically been ascribed to selection for large body size in cold winter climates. Here, in spatially distributed observational data from 30 populations of House Sparrow (Passer domesticus) introduced into Australia and New Zealand, we show that this relationship appears to be explained by a negative relationship with high temperatures during the breeding season. Our results suggest that higher temperatures during the breeding season could reduce body size through developmental plasticity, which should be considered in combination with or as an alternative to selection. Our findings would predict that a hotter climate during breeding could drive significant changes in morphology among populations (and potentially within populations as well, if climate varies temporally across a breeding season). This idea, and our...

Effect of Body Weight on Reproductive Fitness in Spodoptera Litura (Lepidoptera: Noctuidae)

The exact nature and even existence of the balance between natural and sexual selection are still controversial. Body size is a key determinant of an organism’s ecological and physiological properties. It is widely accepted that selection for higher fecundity is the main force behind the selection for larger body size. However, there are conflicting selection pressures operating on body size of both sexes in many organisms, for instance, natural selection for higher survival might reduce body size. In the present study, we found that in the common cutworm moth, Spodoptera litura, female fecundity and fertility significantly increased with her body weight, while male body weight or female–male weight interaction had no effect on female reproductive output. Results of this study also showed that heavier parents have heavier male and female offspring than those from lighter parents. Although not statistically significant, offspring from heavy and light parents showed lower survival rate than those from average weight parents.

Prey morphology and predator sociality drive predator prey preferences

Predator prey preferences shape the dynamics of predator–prey assemblages. Understanding the determinants of a predator’s prey preferences is therefore important. Trends in prey preferences of the large African predators have been described at a species scale, limiting our ability to assess the influence of prey morphology (size and horns) and predator social structure (sex and sociality) on prey preferences. An analysis of cheetah Acinonyx jubatus kill and prey abundance information from throughout South Africa shows that the presence of prey horns and the type of cheetah social group interact with prey size to influence cheetah prey preference. The size threshold above which prey is avoided by cheetah is lower for horned prey than non-horned prey, providing evidence that horns are a predation deterrent in medium-sized prey. Horned females occur significantly more frequently in antelope species on the cusp of being too large for cheetah predation, supporting the hypothesis that horns evolved as an antipredator defense in the females of medium-sized prey. Male coalition cheetah have access to a broader weight range of prey than solitary cheetah, which may infer fitness benefits by way of expanded resource options. The prey weight range accessible to solitary male cheetah is similar to that accessible to solitary female cheetah, suggesting that, in the absence of cooperative hunting, the slightly larger size of the male cheetah infers no hunting advantage. These findings provide insight into the predation pressures driving the evolutionary selection for large body size and horns in prey, and expanded resource access leading to predator sociality.

Genetic responses to seasonal variation in altitudinal stress: whole-genome resequencing of great tit in eastern Himalayas.

Species that undertake altitudinal migrations are exposed to a considerable seasonal variation in oxygen levels and temperature. How they cope with this was studied in a population of great tit (Parus major) that breeds at high elevations and winters at lower elevations in the eastern Himalayas. Comparison of population genomics of high altitudinal great tits and those living in lowlands revealed an accelerated genetic selection for carbohydrate energy metabolism (amino sugar, nucleotide sugar metabolism and insulin signaling pathways) and hypoxia response (PI3K-akt, mTOR and MAPK signaling pathways) in the high altitudinal population. The PI3K-akt, mTOR and MAPK pathways modulate the hypoxia-inducible factors, HIF-1α and VEGF protein expression thus indirectly regulate hypoxia induced angiogenesis, erythropoiesis and vasodilatation. The strategies observed in high altitudinal great tits differ from those described in a closely related species on the Tibetan Plateau, the sedentary ground tit (Parus humilis). This species has enhanced selection in lipid-specific metabolic pathways and hypoxia-inducible factor pathway (HIF-1). Comparative population genomics also revealed selection for larger body size in high altitudinal great tits.

Ideal body condition improves reproductive performance and influences genetic health in female mink

Selection for large body size in mink (Neovison vison) can result in obesity, which is associated with poor reproduction and metabolic disorders. Caloric restriction is effective in diminishing oxidative stress and delaying aging-related diseases. This study investigated the effects of moderate diet restriction on body condition, health, and reproductive success of mink breeder females. One-hundred control females were fed according to conventional feeding practice, while the feed allowance of their 100 sister-pair females was restricted in order to maintain an ideal body condition during the fall and eliminate the need for drastic slimming prior to breeding. Repeated measures analyses revealed that body weight gain during the fall and weight loss prior to breeding was significantly less for the restricted females. The restricted females had significantly larger live litters (5.88 kits) than the control dams (4.62 kits; P<0.05). They were also able to maintain their body weight and condition during early lactation and were able to regain weight and condition post-lactation, unlike their control sisters. Based on their comet scores (restricted: 88; control: 116), the restricted primiparous females experienced less DNA damage (P<0.05), while no significant differences were apparent for the multiparous females (restricted: 170; control: 153). No changes in telomere length were observed among the dams. Moderate diet restriction of mink breeder females during the fall eliminated extreme fluctuations in body weight and condition throughout the seasonal production cycle and improved their litter size, and in primiparous females, lessened DNA damage.

Ecological Specialization in Fossil Mammals Explains Cope’s Rule

Cope's rule is the trend toward increasing body size in a lineage over geological time. The rule has been explained either as passive diffusion away from a small initial body size or as an active trend upheld by the ecological and evolutionary advantages that large body size confers. An explicit and phylogenetically informed analysis of body size evolution in Cenozoic mammals shows that body size increases significantly in most inclusive clades. This increase occurs through temporal substitution of incumbent species by larger-sized close relatives within the clades. These late-appearing species have smaller spatial and temporal ranges and are rarer than the incumbents they replace, traits that are typical of ecological specialists. Cope's rule, accordingly, appears to derive mainly from increasing ecological specialization and clade-level niche expansion rather than from active selection for larger size. However, overlain on a net trend toward average size increase, significant pulses in origination of large-sized species are concentrated in periods of global cooling. These pulses plausibly record direct selection for larger body size according to Bergmann's rule, which thus appears to be independent of but concomitant with Cope's.

Male-Male Competition in a Mixed-Mating Fish

Mating systems that comprise a mixture of pure males and self-fertilising hermaphrodites remain an evolutionary enigma. In particular, our understanding of the sexual selection pressures associated with such mating systems is nascent. Males can only reproduce by fertilising hermaphrodites’ eggs, but hermaphrodites can also fertilise their own eggs and gain a genetic advantage by doing so. Consequently, there should be intense competition among males to access hermaphrodites. Here, we test the importance of male size, colour and heterozygosity in predicting the outcome of male–male competition using the mangrove rivulus, which has a male-hermaphrodite mixed-mating system. We pitted males against one another in dyadic laboratory trials to develop a dominance score for each male. We then correlated these scores with male length, several components of male colour, and heterozygosity. Male size was the only significant correlate of dominance: larger males dominated smaller males, implying selection for large male size. However, male mangrove rivulus are similar in size to hermaphrodites, indicating that directional selection for large body size in males is no greater than it is in hermaphrodites. Across all trials, colour was unrelated to dominance, but contests between similarly sized males were usually won by more colourful individuals. As mangrove rivulus are dichromatic, we suspect that male colour may prove to be more important in mate choice than we found it to be in intrasexual competition. Heterozygosity did not explain dominance directly, but correlated strongly with male size, implying an indirect role in intrasexual competition.

Growth and survivorship as proximate causes of sexual size dimorphism in peninsula dragon lizards Ctenophorus fionni

AbstractMales and females differ in body size in many animals, but the direction and extent of this sexual size dimorphism (SSD) varies widely. Males are larger than females in most lizards of the iguanian clade, which includes dragon lizards (Agamidae). I tested whether the male larger pattern of SSD in the peninsula dragon lizard, Ctenophorus fionni, is a result of sexual selection for large male size or relatively higher mortality among females. Data on growth and survivorship were collected from wild lizards during 1991–1994. The likelihood of differential predation between males and females was assessed by exposing pairs of male and female lizards to a predator in captivity, and by comparing the frequency of tail damage in wild‐caught males and females. Male and female C. fionni grew at the same rate, but males grew for longer than females and reached a larger asymptotic size (87 mm vs. 78 mm). Large males were under‐represented in the population because they suffered higher mortality than females. Predation may account for some of this male‐biased mortality. The male‐biased SSD in C. fionni resulted from differences in growth pattern between the sexes. The male‐biased SSD was not the result of proximate factors reducing female body size. Indeed SSD in this species remained male‐biased despite high mortality among large males. SSD in C. fionni is consistent with the ultimate explanation of sexual selection for large body size in males.

Developmental constraints on the evolution of wing‐body allometry in Manduca sexta

Artificial selection on body size in Manduca sexta produced genetic strains with large and small body sizes. The wing-body allometries of these strains differed significantly from the wild type. Selection on small body size led to a change in the scaling of wing and body size without changing the allometry: the wings were smaller relative to the body, but to the same degree at all body sizes. Selection for large body size led to a change in allometry with a decrease in the allometric coefficient, wing size becoming progressively smaller relative to body as body size increased. When larvae were deprived of food so as to produce adults of a range of small body sizes, all strains retained the same allometric coefficient but showed an increase in the scaling factor. Thus individuals starved as larvae had a smaller adult body size but had proportionally larger wings than fed individuals. We analyzed the developmental processes that could give rise to this pattern of allometries. Differences in the relative growth of body and wing disks can account for the differences in the allometric coefficients among the three body size strains. The change in wing-body allometry at large body sizes was primarily due to an insufficient time period for growth. The available time period for growth of the wing imaginal disks poses a significant constraint on the proportional growth of wings, and thus on the evolution of large body size.

Genetic and phenotypic parameters of age at first mating, litter size and animal size in Finnish mink

Mink skin size in Finland, as well as in other countries, has increased considerably during last decade. However, there are signs that selection for large body size has a negative impact on litter size (LS) and also for survival of kits. Therefore, it is important to study the genetic relationships among fertility traits and animal size (AS). The variance components for age at first mating (AFM) and first three parity LS and AS were estimated using multi-trait restricted maximum likelihood animal model. Data included 82 945 animals born during 1990 to 2004, originating from nine farms. Heritability estimates for the fertility traits were from 0.10 to 0.15. For AS, heritability was estimated to be 0.18. Genetic correlation between AS and all fertility traits was estimated to be negative (varying from −0.004 to −0.38). It is important to recognize this antagonistic relationship and include the reproductive traits into breeding goals to maintain good reproductive performance when selecting for increased body size and hence larger pelts in fur animals. Genetic correlations between the traits should be accounted in breeding value evaluations by using a multi-trait model. Including AFM into breeding value estimation would also improve the accuracy of breeding value estimation for fertility, because females missing the first LS still have record on AFM.

Environmental and genetic influences on queen and worker body size in the social wasp Vespula maculifrons

Many social insects exhibit morphologically distinct worker and queen castes that perform different functions. These functional differences may generate unique selection regimes operating on body size. For example, queens may be under directional selection for large body size, whereas directional selection on worker body size may be limited. Such contrasting selection pressures may differentially affect levels of genetic variation associated with size variation in the two castes. This study sought to determine if genetic effects underlying phenotypic differences varied between the worker and queen castes of the social wasp Vespula maculifrons. We predicted that directional selection would remove genetic variation associated with size differences in the queen caste, whereas a lack of directional selection would tend to maintain genetic variation associated with size differences in the worker caste. We thus (1) calculated broad and narrow sense heritabilities for several morphological traits, (2) examined whether some paternal genotypes produced more morphologically diverse offspring than others, and (3) determined whether trait size variation was associated with genetic variation within colonies. We found that few morphological traits were significantly heritable, indicating that little genetic variance for those traits existed within our study population. We also found that some patrilines produced more morphologically variable offspring than others, suggesting a role of genotype in phenotypic plasticity. And finally, no significant correlations between genetic diversity arising from multiple mating by queens within colonies and trait variation in either caste were found. Overall, our findings indicate a weak effect of genotype on both worker and queen body size variation and are suggestive of a large environmental influence on morphological trait size. Moreover, our results do not indicate that levels of genetic variation underlying size variation differ substantially between castes in this species.

Atmospheric Hypoxia Limits Selection for Large Body Size in Insects

BackgroundThe correlations between Phanerozoic atmospheric oxygen fluctuations and insect body size suggest that higher oxygen levels facilitate the evolution of larger size in insects.Methods and Principal FindingsTesting this hypothesis we selected Drosophila melanogaster for large size in three oxygen atmospheric partial pressures (aPO2). Fly body sizes increased by 15% during 11 generations of size selection in 21 and 40 kPa aPO2. However, in 10 kPa aPO2, sizes were strongly reduced. Beginning at the 12th generation, flies were returned to normoxia. All flies had similar, enlarged sizes relative to the starting populations, demonstrating that selection for large size had functionally equivalent genetic effects on size that were independent of aPO2.SignificanceHypoxia provided a physical constraint on body size even in a tiny insect strongly selected for larger mass, supporting the hypothesis that Triassic hypoxia may have contributed to a reduction in insect size.

Atmospheric hypoxia limits selection for large body size in insects

AbstractRecent geological models indicate a marked increase in atmospheric oxygen partial pressure (aPO~2~) to 32 kPa in the Permo-Carboniferous (approx. 300 million years ago), subsequently falling to 13 kPa in the Triassic^1^.These aPO~2~ changes have been hypothesized to cause multiple major evolutionary events^2^ including the appearance and subsequent extinction of giant insects and other taxa^3, 4^. Patterns of increasing tracheal investment in larger insects support this hypothesis^5^, as do observations of positive relationships between aPO~2~ and body size in single- or multi-generational experiments with Drosophila melanogaster and other insects^6^. Large species likely result from many generations of selection for large body size driven by predation, competition or sexual selection^7^. Thus a crucial question is whether aPO~2~ influences the capacity of such selection to increase insect size. We tested that possibility by selecting for large body size in five Drosophila melanogaster populations for 11 generations in hypoxic (10 kPa), normoxic (21 kPa) and hyperoxic (40 kPa) aPO~2~, followed by three generations of normoxia without size selection to test for evolved responses. Average body sizes increased by 15% during 11 generations of size selection in 21 and 40 kPa aPO~2~ flies and even stronger responses were observed for the flies in the largest quartile of body masses. However, flies selected for large size in 10 kPa aPO~2~ had strongly reduced sizes compared to those in higher aPO~2~. Upon return to normoxia, all flies had similar, enlarged sizes relative to the starting populations. These results demonstrated that positive size selection had equivalent genetic effects on all flies independent of aPO~2~, but that hypoxia provided a physical constraint on body size even in a relatively small insect under strong selection for larger mass. Our data support the hypothesis that Triassic hypoxia may have contributed to a reduction in insect size.

EVOLUTION OF BODY SIZE IN THE MAP TURTLES AND SAWBACKS (EMYDIDAE: DEIROCHELYINAE: GRAPTEMYS)

Map turtles and sawbacks (Emydidae: Deirochelyinae: Graptemys) are a diverse group of turtles that are of ecological interest due to their diversity in trophic morphology, particularly in females, and their extreme sexual size dimorphism (with females larger). I used comparative analyses (independent contrasts in correlation analyses and GLM analyses) to examine hypotheses regarding the evolution of body size in the genus. Evolutionary changes in body size of both males and females were positively related to inferred shifts in latitude. Trophic morphology (relative head width, expressed either as a continuous or a discrete variable) was not an additive source of variation in male body size, but was for female body size, primarily due to the large body sizes exhibited by the megacephalic southern clade (G. pulchra, G. ernsti, G. gibbonsi, and G. barbouri). Status as allopatric or sympatric to other species of Graptemys was not an additive source of variation in female body size. These results argue against the hypothesis that character displacement of body size in females was important in the radiation of map turtle and sawback species and instead suggest a functional relationship whereby degree of molluscivory in females covaries with body size. Sexual size dimorphism was found to increase with body size of females, also due primarily to the large females of the megacephalic clade; this result means Graptemys is an exception to Rensch's Rule. In a latitude-corrected analysis of body size evolution in deirochelyine turtles, the exceptional degree of sexual size dimorphism in Graptemys appears to result more from reduction in male size than increase in female size. Decreased male size may indicate relaxed selection for large body size in Graptemys males as a consequence of the fact that they rarely leave the water for terrestrial excursions, because selection for larger male body size in other deirochelyines may be mediated by (a) predation pressure imposed by terrestrial predators, (b) enhancement of overland mobility for mate searching, and (c) the need for resistance to desiccation during overland excursions. Alternatively, male body size reduction in Graptemys may be explained by energetic requirements of searching for mates in the fluvial environment or unknown differences in social structure among deirochelyine turtles.

Size breeds success: multiple paternity, multivariate selection and male semelparity in a small marsupial, Antechinus stuartii

Mating in the marsupial genus Antechinus is a synchronous annual event that is characterized by monoestry in females and abrupt postmating mortality in males. Male semelparity (multiple copulations during a single breeding season per lifetime) is often assumed to occur as a consequence of the intense mating effort expended by males in the rut, but the forces selecting for this remain elusive. Here, we investigate selection in male brown antechinus, Antechinus stuartii, and test two hypotheses for the evolution of semelparity: intermale competition and sperm competition. If intermale competition drives semelparity, we predicted that males would be under strong selection for large body size. If sperm competition is important, we predicted that selection would be strongest on scrotal size, a surrogate for testes volume. Using microsatellite markers, we found that 92% of females in free-living conditions mated with multiple males, producing litters of eight that had up to four fathers. These observations confirm the potential for sperm competition. Using selection analysis, we then found paternity success in 119 males to be related most strongly to body mass and scrotal size, thus providing support for both hypotheses. Large males presumably experience increased paternity success by gaining more matings or prolonged copulations via mate guarding, while large testes may allow increased sperm investment per copulation. Increased levels of free corticosteroid hormones in males facilitate the extreme mating effort during the short period of rut, but lead to immune suppression and consequently to the phenomenon of postmating mortality.

Reproductive ageing and sexual selection on male body size in a wild population of antler flies (Protopiophila litigata)

Little is known about the importance of trade-offs between ageing and other life history traits, or the effects of ageing on sexual selection, particularly in wild populations suffering high extrinsic mortality rates. Life history theory suggests that trade-offs between reproduction and somatic maintenance may constrain individuals with higher initial reproductive rates to deteriorate more rapidly, resulting in reduced sexual selection strength. However, this trade-off may be masked by increased condition dependence of reproductive effort in older individuals. We tested for this trade-off in males in a wild population of antler flies (Protopiophila litigata). High mating rate was associated with reduced longevity, as a result of increased short-term mortality risk or accelerated ageing in traits affecting viability. In contrast, large body size was associated with accelerated ageing in traits affecting mating success, resulting in reduced sexual selection for large body size. Thus, ageing can affect sexual selection and evolution in wild populations.