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opencc-by-4.0Mar 2013View details →

Fig. 1. Residentmalependulinetitsreacttoplaybacksongandadummypendulinetit aroundtheirnest. Behaviouralresponsesincludedattacking, i.e in Acoustic Signalling In Eurasian Penduline Tits Remiz Pendulinus: Repertoire Size Signals Male Nest Defence

Fig. 1. Residentmalependulinetitsreacttoplaybacksongandadummypendulinetit aroundtheirnest. Behaviouralresponsesincludedattacking, i.e. peckingatthedummy, as

opencc-by-4.0Mar 2013View details →

Fig. 2 in Acoustic Signalling In Eurasian Penduline Tits Remiz Pendulinus: Repertoire Size Signals Male Nest Defence

Fig. 2. SonogramsofsometypicalsyllabletypesofEurasianpendulinetits. Songbouts mayconsistofvarioussyllables (topandbottomsonograms) ormayincludemonotone

opencc-by-4.0Mar 2013View details →

Fig. 3 in Acoustic Signalling In Eurasian Penduline Tits Remiz Pendulinus: Repertoire Size Signals Male Nest Defence

Fig. 3. Approachdistance (a) and % behaviouralresponses (b) towardsanintruderinre- lationtotheresidentmale'sownrepertoiresize. Behaviouralresponsesincludedcalling, singing, tailquiveringandattacking. Opencirclesindicateresponsesofchallengedresi- dentsonsmallrepertoireplayback, whereasfilledcirclesindicatethesamemales' respons- esonlargerepertoireplayback. Notethatpointsshownontheupperhalfregionof (a) represent males that were mostly present very close to their nest (15 m from the stimulus,

opencc-zeroAug 2022View details →

Onthophagus babirussa sexual size dimporphism and male sexual trait files and R codes

Sexual size dimorphism (SSD) arises when natural selection and sexual selection act differently on males and females. Male-biased SSD is rare in insects and usually indicates strong selection pressure on a population or species. Patterns of SSD can also vary between populations of species that are exposed to different environmental conditions, such as differing resource availability and diversity. Here, we investigate intra-specific variation in SSD as well as relative investment in precopulatory (horn length) and postcopulatory traits (sperm length and testes weight) in a tropical rainforest dung beetle Onthophagus babirussa across Singapore and Peninsular Malaysia. Overall, three out of four populations displayed significant male-biased SSD and SSD was greater in populations with smaller overall body size. Average male body size was similar across all populations while female body size was significantly smaller in Singapore, suggesting that the pronounced SSD may also be due to stronger sexual selection on male body size in Singapore populations. All populations showed significant investment in horns as a weapon used in precopulatory competition, while postcopulatory traits showed no clear scaling relationship with body size, suggesting a higher priority on precopulatory sexual traits in the mating system of this species.

opencc-by-4.0Dec 2010View details →

Fig 2 in Sexual Size Dimorphism In Free-Living Populations Of Mus Musculus: Are Male House Mice Bigger?

Fig 2. Variation in SSD during the first five weeks of postnatal development in five mice populations. SSD is expressed as Lowich-Gibbons ratios of mean body weight (see under Material and Methods)

opencc-by-4.0Dec 2010View details →

Fig. 1 in Sexual Size Dimorphism In Free-Living Populations Of Mus Musculus: Are Male House Mice Bigger?

Fig. 1. Map of the studied localities: 1 = Czech Republic, 2 = The Balkans, 3 = Iran, 4 = Jordan, 5 = hybrids. See Material and Methods for coordinates of the localities

opencc-by-4.0Oct 2012View details →

Name Size Figure 4.2. Ratio of male to female participants-The Effects of CALL on Vocabulary Learning: A Case of Iranian Intermediate EFL Learners

In the past, vocabulary teaching and learning were often given little priority in second language programs but recently there has been a renewed interest in the nature of vocabulary and its role in learning and teaching. Although most teachers might be aware of the importance of technology, say, computer, rarely teachers use it for teaching vocabulary. Thus, the current study aims at exploring the effects of CALL on vocabulary learning of Iranian EFL Learners. In this study, 40 intermediate EFL learners, both male and female aged from 16 to 18 studying New Interchange, book III, were chosen randomly from a language institute in Tehran. They were divided into two twenty-member groups. The experimental group was given the VTS.S (a computer program for teaching vocabularies), a computerized dictionary and provided with teacher efeedback. The control group received no special software and vocabularies were taught using the conventional ways with the help of a paper dictionary.

opencc-zeroAug 2023View details →

Data from: The role of male body size in mating success and male-male competition in a false widow spider

In many animals, body size is correlated with reproductive success. Selection sometimes generates striking differences in body size between males and females (i.e., sexual size dimorphism, SSD). SSD is common in spiders (Araneae), and is typically explained by selection for larger, more fecund females, and rapidly maturing, and consequently smaller males. Within a species males and females also often vary in body size. In the false widow spider (Steatoda grossa), females are larger than males and males trade off body size for rapid development and early maturation. Moreover, males exhibit considerable variation in body size, suggesting that under certain conditions there may be advantages to large size. Here, we tested the role of male body size on mating success under non-competitive and competitive mating conditions (i.e., male-male competition) in S. grossa. We found that body size did not influence mating success or copulation duration under non-competitive conditions, but that larger males were more successful at obtaining access to females under competitive mating conditions. Additionally, we found that total copulation duration was significantly lower when a rival male was present. Our results show a large male advantage under male-male competition, which we suggest may contribute to the high variation in male body size observed in S. grossa. We further suggest that the reduced copulation duration observed under competitive mating conditions may have potential ramifications for male and female reproductive success, and discuss how patterns of selection acting on male body size might limit the extent of SSD in this species.

publicAug 2023View details →

Data from: The role of male body size in mating success and male-male competition in a false widow spider

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publicSep 2025View details →

Sexual selection in wild populations of seed bugs: the role of size in pre-copulatory mate choice by females and males

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publicAug 2022View details →

Onthophagus babirussa sexual size dimporphism and male sexual trait files and R codes

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opencc-zeroJul 2020View details →

Data from: The size, symmetry, and color saturation of a male guppy's ornaments forecast his resistance to parasites

Sexually selected ornaments range from highly dynamic traits to those that are fixed during development and relatively static throughout sexual maturity. Ornaments along this continuum differ in the information they provide about the qualities of potential mates, such as their parasite resistance. Dynamic ornaments enable real-time assessment of the bearer's condition: they can reflect an individual's current infection status, or resistance to recent infections. Static ornaments, however, are not affected by recent infection but may instead indicate an individual's genetically-determined resistance, even in the absence of infection. Given the typically aggregated distribution of parasites among hosts, infection is unlikely to affect the ornaments of the vast majority of individuals in a population: static ornaments may therefore be the more reliable indicators of parasite resistance. To test this hypothesis, we quantified the ornaments of male guppies, Poecilia reticulata, before experimentally infecting them with Gyrodactylus turnbulli. Males with more left-right symmetrical black coloration and those with larger areas of orange coloration, both static ornaments, were more resistant. However, males with more saturated orange coloration, a dynamic ornament, were less resistant. Female guppies often prefer symmetrical males with larger orange ornaments, suggesting parasite-mediated natural and sexual selection act in concert on these traits.

opencc-zeroAug 2020View details →

Data from: Effects of female group size on the number of males in blue monkey (Cercopithecus mitis) groups

The number of males per group varies substantially in group-living primates, both between and within species. In blue monkeys (Cercopithecus mitis), males may temporarily join groups during annual mating seasons when sexually receptive females are present. A likely determinant of the number of males per group is female group size (the number of adult females in a group). To clarify the role of female group size in driving variation in the number of males per group, we expanded on earlier observations of a wild population in the Kakamega Forest, Kenya with a larger sample of groups that varied five-fold in female group size. We found considerable flexibility in social organization, with groups experiencing multi-male episodes both during and outside mating seasons, some persisting over multi-year periods. The dichotomy between single- and multi-male mating seasons was less distinct than previously reported, suggesting greater variation in multi-male states. Across 65 group-specific conception periods, female group size strongly influenced how often multiple sexually active females and multiple males were present in a group. The number of sexually active females present on a given day related closely to the number of males in the group that same day, especially during conception periods. Results suggest that males join and remain in larger groups where mating opportunities are greater and costs of joining or staying may be lower than in smaller groups. This longitudinal study highlights intraspecific social variation within and across groups while confirming that female group size influences the number of males.

opencc-zeroJan 2021View details →

Different effects of mating group size as male and as female on sex allocation in a simultaneous hermaphrodite

Sex allocation theory predicts that the optimal sexual resource allocation of simultaneous hermaphrodites is affected by mating group size (MGS). Although the original concept assumes that the MGS does not differ between male and female functions, the MGS in the male function (MGSm; i.e., the number of sperm recipients the focal individual can deliver its sperm to plus one) and that in the female function (MGSf; the number of sperm donors plus one) do not always coincide and may differently affect the optimal sex allocation. Moreover, reproductive costs can be split into "variable" (e.g., sperm and eggs) and "fixed" (e.g., genitalia) costs, but these have been seldom distinguished in empirical studies. We examined the effects of MGSm and MGSf on the fixed and variable reproductive investments in the sessilian barnacle Balanus rostratus. The results showed that MGSm had a positive effect on sex allocation, whereas MGSf had a nearly significant negative effect. Moreover, the "fixed" cost varied with body size and both aspects of MGS. We argue that the two aspects of MGS should be distinguished for organisms with unilateral mating.

opencc-zeroMar 2024View details →

The condition-dependence of male genital size and shape

The male genitals of internal fertilizers evolve rapidly and divergently, and sexual selection is generally responsible for this. Many sexually selected traits are condition-dependent - with their expression dependent upon the resources available to be allocated to them - as revealed by genetic or environmental manipulations of the condition. However, it is not clear whether male genitals are also condition-dependent. Here we manipulate the condition in two ways (via inbreeding and diet) to test the condition-dependence of the genital arch of Drosophila simulans. We found that genital size but not genital shape suffered from inbreeding depression, whereas genital size and shape were affected by dietary manipulation of the condition. The differential effects of these treatments likely reflect the underlying genetic architecture that has been shaped by past selection: inbreeding depression is only expected when traits have a history of directional selection, while diet impacts traits regardless of historical selection. Nonetheless, our results suggest genitals can be condition-dependent like other sexually selected traits.

opencc-zeroMay 2022View details →

Data from: female preference for super-sized male ornaments and its implications for the evolution of ornament allometry

It has been argued that disproportionately larger ornaments in bigger males—positive allometry—is the outcome of sexual selection operating on the size of condition dependent traits. We reviewed the literature and found a general lack of empirical testing of the assumed link between female preferences for large ornaments and a pattern of positive allometry in male ornamentation. We subsequently conducted a manipulative experiment by leveraging the unusual terrestrial fish, Alticus sp. cf. simplicirrus, on the island of Rarotonga. Males in this species present a prominent head crest to females during courtship, and the size of this head crest in the genus more broadly exhibits the classic pattern of positive allometry. We created realistic male models standardized in body size but differing in head crest size based on the most extreme allometric scaling recorded for the genus. This included a crest size well outside the observed range for the study population (super-sized). The stimuli were presented to free-living females in a manner that mimicked the spatial distribution of courting males. Females directed greater attention to the male stimulus that exhibited the super-sized crest, with little difference in attention direct to other size treatments. These data appear to be the only experimental evidence from the wild of a female preference function that has been implicitly assumed to drive selection that results in the evolution of positive allometry in male ornamentation.

opencc-zeroOct 2022View details →

Reduced sexual size dimorphism in a pipefish population where males do not prefer larger females

Within a species' distribution, populations are often exposed to diverse environments and may thus experience different sources of both natural and sexual selection. These differences are likely to impact the balance between costs and benefits to individuals seeking reproduction, thus entailing evolutionary repercussions. Here, we look into an unusual population (Baltic Sea) of the broadnosed pipefish, Syngnathus typhle, where males do not seem to select females based on size and hypothesise that this pattern may derive from a reduction of direct benefits to the male. We further hypothesise that if larger females do not persistently secure a higher reproductive success, either through pre- or post-copulatory sexual selection, a decrease in sexual size dimorphism in the Baltic population should be apparent, especially when contrasted with a well-studied population, inhabiting similar latitudes (Swedish west coast), where males prefer larger females. We found that, in the Baltic population, variation in female quality is low. We were unable to find differences in abortion rates or protein concentration in oocytes produced by females of contrasting sizes. Direct benefits from mating with large partners seem, thus, reduced in the Baltic population. We also found no evidence of any post-copulatory mechanism that could favour larger mothers as embryo development was unrelated to female size. While female size can still be selected through intrasexual competition or fecundity selection, the pressure for large female body size seems to be lower in the Baltic. Accordingly, we found a noticeable decrease in sexual size dimorphism in the Baltic population. We conclude that, although far from negating the significance of other selective process, sexual selection seems to have a decisive role in supporting pipefish sexual size asymmetries.

zenodo36/100

Dataset The relative importance of body size and UV coloration in influencing male-male competition in a Lacertid lizard

This is the dataset of the paper "The relative importance of body size and UV coloration in influencing male-male competition in a Lacertid lizard" published in Behavioral Ecology and Sociobiology by Names et al. (2019). It includes a metadata statement and five data spreadsheets. Abstract of the paper Communication via color signals is common in natural systems. Ultraviolet (UV)-blue patches located on the outer-ventral scales of some Lacertid lizards are thought to be involved in male-male competition. However, the mechanisms that maintain their honesty remain unknown. Here, we use the common wall lizard Podarcis muralis to test whether the lateral UV-blue spots are conventional signals, the honesty of which is guaranteed by receiver-dependent costs, and discuss their potential role as an amplifier of body size. We first described the morphology and reflectance properties of lateral blue spots in common wall lizards and investigated how they influence male- male competition. Spot size and number, UV chroma, and conspicuousness (calculated using vision models) were significantly greater in adult males relative to adult females and adult males relative to juveniles. Total spot area (and not spot number) of adult males was positively correlated with body size. We conducted staged competition encounters between focal males and smaller or larger rivals with control or manipulated spots. Spots were enlarged in small rivals and reduced in large rivals to disrupt the phenotypic correlation between spot area and body size. Aggressiveness and dominance were positively influenced by body size in control encounters. Spot manipulations resulted in greater submission and less aggressiveness in focal males. These results contradict the predictions associated with conventional signals and amplifiers, but suggest that spots contributed to opponent evaluation during short-distance encounters between competing males.

opencc-by-4.0Jun 2019View details →

opencc-zeroMay 2023View details →

Data for: Size rather than complexity of sexual ornaments prolongs male metamorphosis and explains sexual size dimorphism in sepsid flies

Male sexual ornaments often evolve rapidly and are thought to be costly, thus contributing to sexual size dimorphism. However, little is known about their developmental costs, and even less about costs associated with structural complexity. Here, we quantified the size and complexity of three morphologically elaborate sexually dimorphic male ornaments that starkly differ across sepsid fly species (Diptera: Sepsidae). Male forelegs range from being unmodified, like in most females, to being adorned with spines and large cuticular protrusions. The 4th abdominal sternites are either unmodified or are converted into complex de novo appendages. Male genital claspers range from small and simple to large and complex (e.g. bifurcated). We tracked the development of 18 sepsid species from egg to adult to determine larval feeding and pupal metamorphosis times of both sexes. We then statistically explored whether pupal and adult body size, ornament size, and/or ornament complexity are correlated with sex-specific development times. Larval growth and foraging periods of male and female larvae did not differ, but the time spent in the pupal stage was ca. 5% longer for sepsid males despite emerging 9% smaller than females on average. Surprisingly, we found no evidence that sexual trait complexity prolongs pupal development beyond some effects of trait size. Evolving more complex traits thus does not incur developmental costs.