Intrasexually selected weapons

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2018, Номер 94(1), С. 60 - 101

Опубликована: Июнь 20, 2018

ABSTRACT We propose a practical concept that distinguishes the particular kind of weaponry has evolved to be used in combat between individuals same species and sex, which we term intrasexually selected weapons (ISWs). present treatise ISWs nature, aiming understand their distinction evolution from other secondary sex traits, including ‘sexually weapons’, sexually dimorphic monomorphic weaponry. focus on subset traits are result same‐sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, offer hypotheses answer questions such as: why have only some fight for opposite or breeding resources? examined seem entire animal phylogeny, restricting classification ISW enlarged adults one sexes, during intrasexual fights. Because absence behavioural data and, many cases, lack discriminated series juveniles adults, exclude fossil record this review. merge morphological, ontogenetic, information, first time thoroughly review tree life identify separate ISWs. found bilateral animals, appearing independently nematodes, various groups arthropods, vertebrates. Our sets reference point explore taxa with potential morphological studies warranted. establish most come pairs, located near head, endo‐ exoskeletal modifications, overdeveloped structures compared those females, modified feeding and/or locomotor appendages, common terrestrial taxa, frequently guard territories, both, also signalling displays deter rivals attract females. females few possess better‐developed than males, cases independent evenly distributed across animals possessing developed non‐hunting habits (e.g. herbivores) faunivores prey very small relative body size insectivores). Bringing together perspectives variety conceptualize there five ways trait, apart primary can fixed: sexual selection, fecundity parental role division, differential niche occupation interference competition. discuss these trends factors involved nature.

Язык: Английский

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Male alternative reproductive tactics and sperm competition: a meta‐analysis

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2022, Номер 97(4), С. 1365 - 1388

Опубликована: Фев. 28, 2022

ABSTRACT In many animal species, males may exhibit one of several discrete, alternative ways obtaining fertilisations, known as reproductive tactics (ARTs). Males exhibiting ARTs typically differ in the extent to which they invest traits that improve their mating success, or face sperm competition. This has led widespread prediction associated with a high competition risk, lower investment into competitiveness before mating, should more heavily after such large ejaculates and high‐quality sperm. However, despite studies investigating this question since 1990s, evidence for differences ejaculate between male is mixed, there been no quantitative summary field. Following systematic review literature, we performed meta‐analysis examining how testes size, number either low increase success. We obtained data from 92 67 species across kingdom. Our analyses showed fish facing risk had significantly larger (after controlling body size) than those risk. effect appears be due inappropriate use gonadosomatic index body‐size corrected measure investment, overestimates difference most cases. found significant different ARTs, regardless whether were measured stores following ejaculation. also exception adenosine triphosphate (ATP) content fish. Finally, post‐mating was not influenced by flexible, frequency sneakers population. Overall, our results suggest that, clear theoretical predictions, little substantially species. The incongruence empirical could explained if ( i ) models fail account overall resource levels fundamental trade‐offs traits, ii often do reflect accurately affect fertilisation

Язык: Английский

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Sperm and alternative reproductive tactics: a review of existing theory and empirical data

Philosophical Transactions of the Royal Society B Biological Sciences, Год журнала: 2020, Номер 375(1813), С. 20200075 - 20200075

Опубликована: Окт. 18, 2020

Males that exhibit alternative reproductive tactics (ARTs) often differ in the risk of sperm competition and energetic trade-offs they experience. The resulting patterns selection could lead to between-tactic differences ejaculate traits. Despite extensive research on male ARTs, there is no comprehensive review whether what traits exist between ARTs. We existing theory evolution relevant ARTs then conduct a vote-counting empirical data comparing males adopting general expectation sneaker should produce are more competitive (e.g. higher quality or performance), we find does not predict explicitly how majority studies significant difference performance dominant males. However, when difference, tend have trait values than propose ways future theoretical can improve our understanding highlight studying species with will broader knowledge evolution. This article part theme issue ‘Fifty years competition’.

Язык: Английский

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Squid male alternative reproductive tactics are determined by birth date

Proceedings of the Royal Society B Biological Sciences, Год журнала: 2024, Номер 291(2021)

Опубликована: Апрель 24, 2024

Alternative reproductive tactics (ARTs) are discontinuous phenotypes associated with reproduction, observed in males of many species. Typically, large adopt a tactic competing rivals for mating, while small stealing fertilization opportunities from the males. The ‘birth date hypothesis', proposing that birth influences determination each male's tactic, has been tested only teleost fish to date. Here, hypothesis was ARTs Japanese spear squid Heterololigo bleekeri (consort/sneaker) by analysing statolith growth increments. significantly differed between consorts (early-hatched) and sneakers (late-hatched). However, no differences were detected history up 100 days hatching. Most immature caught during season larger than sneakers, their hatch similar consorts, suggesting these had already following life-history pathway as consort. These results indicate H. determined based on early life. This study firstly suggests applies aquatic invertebrates, mechanism which determines individual phenotype is phenomenon more common previously believed.

Язык: Английский

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Environmental influence on life-history traits in male squid Uroteuthis edulis with alternative reproductive tactics

Marine Biology, Год журнала: 2022, Номер 169(3)

Опубликована: Фев. 3, 2022

Abstract Squid are characterized by flexible life-history traits (LHTs) that change in response to changing oceanic parameters. Male alternative reproductive tactics (ARTs), large-sized ‘consorts’ versus small-sized ‘sneakers’, commonly observed loliginid species. This study reports on LHTs flexibility male squids displaying ARTs. of consorts and sneakers Uroteuthis edulis , including body size, age, growth rate gonado-somatic energy allocation, were compared among seasonal geographical groups from Japan Taiwan. The ratio was highest the group spawning ‘Japan-warm’ season (June–November), followed ‘Japan-cold’ (December–May), lowest Taiwan (spring autumn). cohorts separated hatching catch location (Jwarm, Jcold cohorts). Mean size showed no difference cohorts, although relatively younger than consorts. age decreased with increased water temperature at hatching. Growth rates slightly different accordance differences statolith increment widths during their early life stage (50–150 days). both cohort, Jwarm cohort lowest. Sneakers invested more mantle gonadal weights all cohorts. Gonado-somatic allocation patterns consistent temperatures. U. strongly influenced temperature, higher

Язык: Английский

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Male Alternative Reproductive Tactics and Associated Evolution of Anatomical Characteristics in Loliginid Squid

Frontiers in Physiology, Год журнала: 2019, Номер 10

Опубликована: Окт. 15, 2019

Loliginid squids provide a unique model system to explore male alternative reproductive tactics (ARTs) and their linkage size, behavioral decision making, possibly age. Large individuals fight one another the winners form temporary consortships with females, while smaller do not engage in male-male agonistic bouts but use various sneaker obtain matings, each varying mating fertilization success. There is substantial flexibility most species, as males can facultatively switch consort behaviors context changes. These forms of ARTs involve different: posture; site spermatophore deposition; success; sperm traits. Most traits dimorphism (both anatomical behavioral) are consistent traditional sexual selection theory, others have features that may evolved response environment faced by or permanent morph.

Язык: Английский

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Strategic adjustment of ejaculate quality in response to variation of the socio-sexual environment

Behavioral Ecology and Sociobiology, Год журнала: 2021, Номер 75(6)

Опубликована: Май 14, 2021

Язык: Английский

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Dimorphic ejaculates and sperm release strategies associated with alternative mating behaviors in the squid

Journal of Morphology, Год журнала: 2017, Номер 278(11), С. 1490 - 1505

Опубликована: Июль 18, 2017

Abstract Sperm competition is a powerful postcopulatory selective force influencing male adaptations associated with increasing fertilization success, and it usually related to the evolution of different strategies ejaculate expenditure between individuals. Ejaculates may also be influenced by additional pressures sperm competition, such as timing insemination fertilization, female reproductive tract morphology, environment. Also, males that adopt alternative mating tactics face distinct pressures, which lead intraspecific diversity in ejaculates. In loliginid squids, (sneakers consorts) differ not only behavior, but transfer spermatophores into two sites within female. Here, we compared structure functioning sneakers consorts squid Doryteuthis plei applying microscopy techniques vitro experiments. Sneakers exhibit differences spermatophore spermatophoric reactions spermatangium morphologies. Moreover, sneakers, release lasts longer their show an aggregative behavior detected consorts. Slow strategy guarantee provision, given wide interval sneaker egg release. For consorts, turn, intense quick discharge advantageous, egg‐laying relatively short. Within complex system, factors (i) (ii) influence ultimately shape divergent ejaculates dimorphic males.

Язык: Английский

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Behavior of “Intermediate” Males of the Dimorphic Squid Doryteuthis pleii Supports an Ontogenetic Expression of Alternative Phenotypes

Frontiers in Physiology, Год журнала: 2019, Номер 10

Опубликована: Сен. 13, 2019

The expression of alternative reproductive tactics (ARTs) by different-sized males loliginid squids has been extensively investigated. In loliginids, phenotypes are characterized differences in behavior, body size, sperm deposition site, and morphology functioning ejaculates. Consort guard females, display agonistic behaviors towards rival males, mate with females male-parallel position (MP). Sneaker avoid fights instead adopt furtive to access guarded consort mating the head-to-head posture (HH). Recently, reappraisal preserved material from squid Doryteuthis pleii showed that intermediate-sized (so-called "intermediate" males) had both sneaker- consort- like ejaculates, leading hypothesis them being a transitional stage between phenotypes. Here, we describe observations made captivity showing intermediate can positions, depending on male's current context, i.e., generally HH, but switching MP when female is laying eggs. Such unusual findings simultaneously displaying sneaker comprise additional evidence corroborating ontogenetic for phenotypic ARTs this species. Taken together, our results indicate (1) competing large monopolization, small/young obtain opportunities, (2) as they continue grow, gradually modify their ejaculates going through an stage, before becoming males.

Язык: Английский

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Rare polyandry and common monogamy in the firefly squid, Watasenia scintillans

Scientific Reports, Год журнала: 2020, Номер 10(1)

Опубликована: Июль 3, 2020

Abstract In cephalopods, all species are considered to be polyandrous because of their common life history and reproductive traits reflecting a mating system. Contrary this belief, here we show several lines evidence for monogamy in the firefly squid, Watasenia scintillans . species, females capable long-term storage spermatangia, egg spawning even after complete disappearance males following breeding season. The stored spermatangia distributed equally between bilateral pouches under female’s neck collar. Such nonrandom pattern sperm prompted us hypothesize that might engage lifetime monandry. Hence, genotyped female-stored offspring, found 95% (18/19), had been delivered from single male embryos clutch sired by spermatozoa spermatangia. males, throughout season, relative testis mass was much smaller W. than other cephalopods examined previously. mean number male-stored spermatophores ~ 30, equivalent only 2.5 matings. Our genetic, demographic morphometrical data agree with mathematical model predicting monogyny is favored when potential mates scarce. Together, these results suggest mutual

Язык: Английский

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