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

---

Prenatal sex determination illuminates the unusual adult sex ratio of a group-living lemur

Biology Letters, Journal Year: 2025, Volume and Issue: 21(2)

Published: Feb. 1, 2025

Most mammals, including humans, exhibit even or slightly male-biased birth sex ratios (BSRs) and female-biased adult (ASRs) much later in life due to higher male mortality rates. The group-living primates of Madagascar are unusual this respect because they lack ASRs, but it is unknown whether the result skewed BSRs sex-specific disappearance patterns. Using long-term demographic data from wild red-fronted lemurs ( Eulemur rufifrons ), we analysed their ratio dynamics across lifespan. We assessed BSR via prenatal determination using maternal faecal oestrogen metabolite measurements during late pregnancy, confirming a visually determined equal three months after birth, indicating no early mortality. Demographic analyses additionally disclosed female within first 8 years age, likely associated with reproductive effort life. Thereby, survival had greatest positive effect on ASR. Our study offers rare perspective age- primate population, whose sex-reversed patterns may also contribute more general understanding mechanisms generating sex-biased

Language: Английский

---

Tadpoles Develop Elevated Heat Tolerance in Urban Heat Islands Regardless of Sex

Evolutionary Biology, Journal Year: 2024, Volume and Issue: 51(1), P. 209 - 216

Published: Feb. 3, 2024

Abstract The ability of wildlife to endure the effects high temperatures is increasingly important for biodiversity conservation under climate change and spreading urbanization. Organisms living in urban heat islands can have elevated tolerance via phenotypic or transgenerational plasticity microevolution. However, prevalence mechanisms such thermal adaptations are barely known aquatic organisms. Furthermore, males females differ tolerance, which may lead sex-biased mortality, yet it unknown how sex differences biology influence divergence. To address these knowledge gaps, we measured critical maxima (CT max ) male female agile frog ( Rana dalmatina tadpoles captured from warm ponds cool woodland ponds, a common-garden experiment where embryos collected both habitat types were raised laboratory. We found higher CT urban-dwelling compared their counterparts ponds. This difference was reversed experiment: originating had lower than no effect on its between habitats. These results demonstrate that amphibian larvae respond island with increased similarly other, mostly terrestrial taxa studied so far, be main driver this response. Our findings also suggest heat-induced mortality independent tadpoles, but research needed many more explore potentially sex-dependent responses.

Language: Английский

---

The causes and implications of sex role diversity in shorebird breeding systems

Ibis, Journal Year: 2023, Volume and Issue: 166(2), P. 357 - 385

Published: Oct. 11, 2023

Males and females often exhibit different behaviours during mate acquisition, pair‐bonding parenting, a convenient label to characterize these is sex role. The diverse roles that male female shorebirds (plovers, sandpipers allies) in mating parenting have played key role advancing mainstream theories avian ecology behavioural biology including sexual selection, conflict parental cooperation. Recent advances shorebird research also highlighted the significance of social environment driving by linking adult ratio with breeding behaviour population demography. Here we review using as an ecological model system. We identify knowledge gaps argue untapped potential accelerate fields evolutionary genomics, movement ecology, networks environmental changes. Future studies will benefit from individual‐based monitoring advanced tracking technologies, multi‐team collaborations are facilitated standardized data collection methodologies across species field. These not only contribute our understanding reproductive strategies, but they knock‐on effects on predicting resilience changes prioritizing for conservation.

Language: Английский

---

The evolution of sex roles: The importance of ecology and social environment

Proceedings of the National Academy of Sciences, Journal Year: 2024, Volume and Issue: 121(22)

Published: May 21, 2024

Males and females often have different roles in reproduction, although the origin of these differences has remained controversial. Explaining enigmatic reversed sex where males sacrifice their mating potential provide full parental care is a particularly long-standing challenge evolutionary biology. While most studies focused on ecological factors as drivers roles, recent research highlights significance social such adult ratio. To disentangle propositions, here, we investigate additive interactive effects several role variation using shorebirds (sandpipers, plovers, allies) model organisms that spectrum including some best-known examples sex-role reversal. Our results consistently show play prominent driving roles. Importantly, are associated with both male-skewed ratios high breeding densities. Furthermore, phylogenetic path analyses general support for variations rather than being consequence Together, important open future directions by showing opportunities major generating diversity system, care.

Language: Английский

---

A male-biased sex ratio increases the opportunity for precopulatory sexual selection but does not change the Bateman gradient

Evolution Letters, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 17, 2025

Abstract Theory predicts that the sex ratio within populations should influence strength of sexual selection, and is often used as a proxy for selection. However, recent studies challenge this relationship. We manipulated adult ratios in Drosophila melanogaster to comprehensively investigate relationship between Consistent with theory, we found stronger selection males than females an increased variance male reproductive success (the opportunity selection) male-biased ratios. In addition, faced more intense sperm competition ratios, although structure networks was largely invariant ratio. Despite this, show did not measured by Bateman gradient. leverage randomized null models reconcile these results higher may be explained random chance mating, rather competitive mechanisms. Our findings indicate caution warranted over long-standing assumption bias good

Language: Английский

---

Age-dependent drivers of sex-specific disappearance in wild redfronted lemurs: the role of behavior

Behavioral Ecology and Sociobiology, Journal Year: 2025, Volume and Issue: 79(4)

Published: April 1, 2025

Language: Английский

---

Ex-situ avian sex skews: determinants and implications for conservation

PeerJ, Journal Year: 2025, Volume and Issue: 13, P. e19312 - e19312

Published: April 18, 2025

With over half of all avian species in decline globally, zoo-based recovery programs are increasingly relied upon to save from extinction. The success such not only rests with political will, but also our understanding species’ breeding biology and how individuals populations respond changes their environment. Sex skews, that is, an imbalance the optimal number males females, is underlying mechanism population some threatened species. Ex-situ ( i.e ., zoo-based) management practices will need become more efficient support growing conservation reliant manage sex skews amend, repair restore stability both - ex-situ . In this article, we analysed data 182,000 birds global collections. We interpreted ratio variation by observing proportion within between orders, International Union for Conservation Nature (IUCN) threat status housing inside outside a natural range. Overall, results showed male-biased prevalent than they wild although vary greatly at institutional level, were closer parity level. amongst range less significant. These findings have implications potential function maximum effect integrated system.

Language: Английский

---

Untangling the relationship between pollination efficiency and pollen-ovule ratios

Perspectives in Plant Ecology Evolution and Systematics, Journal Year: 2025, Volume and Issue: unknown, P. 125872 - 125872

Published: April 1, 2025

Language: Английский

---

Variation in adult sex ratios in tetrapods is linked to sex chromosomes through mortality differences between males and females

PLoS Biology, Journal Year: 2025, Volume and Issue: 23(5), P. e3003156 - e3003156

Published: May 12, 2025

Sex chromosomes can determine male and female phenotypes, the resulting sex differences may have significant impacts on ecology life history. One manifestation of this link is that ZW/ZZ sex-determination systems are associated with more male-skewed adult ratio (ASR, proportion males in population) than XX/XY across tetrapods (amphibians, reptiles, birds, mammals). Here, we investigate four demographic processes: offspring production, juvenile mortalities timing maturation contribute to ASR variation between systems, using phylogenetic analyses a large dataset collected from tetrapod species wild. We show mortality reliably predict also male-biased species. time skews, but do not differ consistently systems. Phylogenetic path confirm an influence system through sex-biased mortalities. Together these results infer impact, via pathways, frequency-dependent selection emerging relative number females. call for follow-up studies uncover potentially complex web associations determination, population dynamics, social behavior.

Language: Английский

---