Sex roles and sex ratios in animals

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Journal Year: 2022, Volume and Issue: 98(2), P. 462 - 480

Published: Oct. 28, 2022

ABSTRACT In species with separate sexes, females and males often differ in their morphology, physiology behaviour. Such sex‐specific traits are functionally linked to variation reproductive competition, mate choice parental care, which have all been sex roles. At the 150th anniversary of Darwin's theory on sexual selection, question why patterns roles vary within across remains a key topic behavioural evolutionary ecology. New theoretical, experimental comparative evidence suggests that adult ratio (ASR) is driver Here, we first define discuss historical emergence role concept, including recent criticisms rebuttals. Second, review various ratios focus ASR, explore its theoretical links Third, causes, especially consequences, biased ASRs, focusing results correlational studies effect ASR choice, conflict, care mating systems, social behaviour, hormone fitness. We present animals diverse societies sensitive local even short timescales, propose explanations for conflicting results. conclude an overview open questions this field integrating demography, life history

Language: Английский

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Honey, What's for Dinner? Dietary Overlap and Size Dimorphism Between Female and Male Joro Spiders (Trichonephila clavata)

Integrative Zoology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 15, 2025

ABSTRACT Selection on body size tends to favor larger males that outcompete smaller mate with females, and larger, more fecund females. For many web‐building spiders in the Nephilidae family, reproductive success increases size, which turn, is related diet. The diet of female may overlap who share her web, but patterns could depend if certain have better access prey ensnared web. Therefore, we tested hypothesis Joro spider ( Trichonephila clavata ) dietary are sex‐specific condition. We combined morphometric analysis molecular gut content via DNA metabarcoding high‐throughput sequencing characterize male diets from 60 webs at 25 locations. Female were than their diverse. While consumed same taxa as 50 additional detected diets, led significant dissimilarity composition between sexes. As increased, diversity condition decreased, suggesting a potential trade‐off time spent foraging versus active defense position captured web shared taxa. However, proportion was not size. Combined, show patterns, appear less diverse food webs.

Language: Английский

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The origins and drivers of sexual size dimorphism in sharks

Ecology and Evolution, Journal Year: 2024, Volume and Issue: 14(3)

Published: March 1, 2024

Abstract While sexual size dimorphism (SSD) is abundant in nature, there huge variation both the intensity and direction of SSD. SSD results from a combination selection for large male size, fecundity female ecological either. In most vertebrates, it male–male competition that primarily underlies this study, we test four hypotheses regarding adaptive value sharks—considering potential each fecundity, sexual, reproductive mode as primary driver between species. We also estimate past macroevolutionary shifts direction/intensity through shark phylogeny. were unable to find evidence significant early sharks hypothesise derived state clade, has evolved independently observed other vertebrates. Moreover, no relationship testes mass or oceanic depth sharks. However, support previous speculation an important determinant interspecific This vertebrates thought be trends, with role clades being inconsistent at best. phylogenetic distribution among superficially similar vertebrate clades, relative importance selective pressures underlying its evolution appears differ.

Language: Английский

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Sexual selection and sexual size dimorphism in animals

Biology Letters, Journal Year: 2021, Volume and Issue: 17(9), P. 20210251 - 20210251

Published: Sept. 1, 2021

Sexual selection is often considered as a critical evolutionary force promoting sexual size dimorphism (SSD) in animals. However, empirical evidence for positive relationship between on males and male-biased SSD received mixed support depending the studied taxonomic group method used to quantify selection. Here, we present meta-analytic approach accounting phylogenetic non-independence test how standardized metrics of opportunity strength pre-copulatory relate across broad range animal taxa comprising up 95 effect sizes from 59 species. We found that based length measurements was correlated with sex difference but showed weak statistically non-significant Bateman gradient. These findings suggest plays limited role evolution context.

Language: Английский

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Sex‐specific inbreeding depression: A meta‐analysis

Ecology Letters, Journal Year: 2022, Volume and Issue: 25(4), P. 1009 - 1026

Published: Jan. 21, 2022

Abstract Inbreeding depression, the reduced fitness of offspring related individuals, can affect males and females differently. Although a comprehensive theoretical framework describing causes sex‐specific inbreeding depression is lacking, empirical evidence suggests that often one sex tends to be more vulnerable than other. However, generality, direction, degree difference in remains enigmatic as studies on this topic have reported conflicting results. Here, we conduct meta‐analysis test for differences magnitude depression. We synthetised 321 effect sizes experimental across 47 species found small between sexes: suffered slightly higher males. Furthermore, coefficient was correlated with there large amount heterogeneity remained unexplained, even when considering different factors could sexes, such sexual size dimorphism, heterogamety, type trait measured whether animals were tested stressful environment. As such, highlight need further explore determine occurrence increase our understanding evolutionary consequences

Language: Английский

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Substantial but Misunderstood Human Sexual Dimorphism Results Mainly From Sexual Selection on Males and Natural Selection on Females

Frontiers in Psychology, Journal Year: 2022, Volume and Issue: 13

Published: May 17, 2022

Human sexual dimorphism has been widely misunderstood. A large literature underestimated the effect of differences in body composition and role male contest competition for mates. It is often assumed that sexually dimorphic traits reflect a history selection, but natural selection frequently builds different phenotypes males females. The relatively small sex difference stature (∼7%) its decrease during human evolution have presumed to indicate decreased However, females likely increased relative order successfully deliver large-brained neonates through bipedally-adapted pelvis. Despite mass (∼16%), there are marked composition. Across multiple samples from groups with nutrition, typically 36% more lean mass, 65% muscle 72% arm than women, yielding parallel strength. These strength comparable those seen primates where arising aggressive mating competition, produced high levels dimorphism. Body fat percentage shows reverse pattern, having ∼1.6 times depositing regions males. We argue these adipose arise mainly on women accumulate neurodevelopmental resources.

Language: Английский

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Climate is changing, are European bats too? A multispecies analysis of trends in body size

Ecology and Evolution, Journal Year: 2024, Volume and Issue: 14(2)

Published: Feb. 1, 2024

Abstract Animal size, a trait sensitive to spatial and temporal variables, is key element in ecological evolutionary dynamics. In the context of climate change, there evidence that some bat species are increasing their body size via phenotypic responses higher temperatures at maternity roosts. To test generality this response, we conducted >20‐year study examining changes 15 Italy, analysing data from 4393 individual bats captured since 1995. addition effect, considered potential influence sexual dimorphism and, where relevant, included latitude altitude as drivers change. Contrary initial predictions widespread increase our findings challenge assumption, revealing nuanced interplay factors contributing complexity Specifically, only three ( Myotis daubentonii , Nyctalus leisleri Pipistrellus pygmaeus ) out exhibited discernible over studied period, prompting reassessment reliable indicators change based on alterations size. Our investigation into influencing highlighted significance temperature‐related with emerging crucial drivers. cases, mirrored patterns consistent Bergmann's rule, larger recorded progressively latitudes Plecotus auritus mystacinus Miniopterus schreibersii or altitudes kuhlii ). We also observed clear effect most species, females consistently than males. The time suggests occurrence plasticity, raising questions about long‐term selective pressures individuals. unresolved question whether reflect microevolutionary processes plastic adds further understanding space.

Language: Английский

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Body size prediction in scorpions: a phylogenetic comparative examination of linear measurements of individual body parts

PeerJ, Journal Year: 2025, Volume and Issue: 13, P. e18621 - e18621

Published: Jan. 17, 2025

Body size has always been the focus of several ecological studies due to its undeniable influence on other life-history traits. The conventional representation body in arthropods typically relies linear measures, such as total length, or length specific parts that can be used represent size. While these measures offer simplicity over more complicated alternatives (e.g., dry mass), technical problems persist for with complex structures, is case scorpions. In animals, accurate measurements often require extensive handling, including stretching parts. light difficulties associated directly measuring and carapace scorpions (two prevalent proxies group), this study evaluates ability seven simple predicting boy under a phylogenetic framework. Predictive equations derived from mixed models fitted Bayesian framework were implemented custom R functions applied prediction wide range Overall, predictions could achieved using any studied traits single predictors. However, most obtained metasomal segment V, while best telson length. addition secondary predictor had low impact quality predictions, indicating increasing model complexity by incorporating additional predictors not necessary achieve estimates. Technical advantages limitations each measurement are discussed. conclusion, broadens repertoire methods available accurately estimating scorpions, particularly instances where information only indirectly through allometric relationships.

Language: Английский

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Instar determination, development, and sexual dimorphism for Gynaephora menyuanensis (Lepidoptera: Lymantriinae) and ultrastructure of adult antennae

Journal of Insect Science, Journal Year: 2025, Volume and Issue: 25(2)

Published: March 1, 2025

Abstract Gynaephora menyuanensis Yan & Zhou is one of the most devastating pests that harm ecosystem alpine meadows and hinder advancement animal husbandry. However, current knowledge morphology different developmental stages within G. reveals an information deficit needs to be addressed. This study first report life history, sexual dimorphism, eggs, mature larvae, pupae, adult antennal sensilla types menyuanensis. used a K-means clustering method, based on head width, body length, number crochets larvae at each instar, differentiate instars menyuanensis; description antennae employed light microscopy scanning electron photographs. The results revealed instar grouping was reliable verified by Brooks-Dyar combined with Crosby rules, revealing larval stage comprises 7 instars. species produces generation per year in meadow, its cycle lasting approximately 300 d total. pupae significantly differed between sexes, indicating dimorphism 2 genders. Nine 14 subtypes were observed male (bipectinate), while only 3 found female (club-like). Our findings have implications for better understanding adaptation strategies under extreme environmental conditions Qinghai-Tibet Plateau developing scientific effective pest control methods.

Language: Английский

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Do olive ridley turtles select mates based on size? An investigation of mate size preference at a major arribada rookery

Ecosphere, Journal Year: 2025, Volume and Issue: 16(4)

Published: April 1, 2025

Abstract We investigated mate size preferences in olive ridley sea turtles ( Lepidochelys olivacea ), one of the world's smallest and most abundant turtle species, using data from two years near a single mass nesting site. Even though past research has focused on many aspects reproductive biology these turtles, not much is known about their preference related behaviors. Our study large number that congregated for mating nearshore waters before nesting. captured, tagged, measured 268 individuals (134 pairs), analyzing correlation between male female carapace length to test assortative found significant positive correlation. Larger females produce more eggs, larger males can have physical advantages during mating, we think factors drive size‐based mating. also observed frequent biting scar marks multiple attempting with individual females, suggesting competition These findings enhance our understanding behavior, specifically choice size.

Language: Английский

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