Inferring social behavior from sexual dimorphism in the fossil record

2000 ◽  
Vol 39 (3) ◽  
pp. 327-344 ◽  
Author(s):  
J.Michael Plavcan
Keyword(s):  
Sexual Dimorphism ◽  
Social Behavior ◽  
Fossil Record

scholarly journals The ander's organ: a mechanism for anti-predator ultrasound in a relict orthopteran

2020 ◽  
pp. jeb.237289
Author(s):  
Charlie Woodrow ◽  
Kevin A. Judge ◽  
Christian Pulver ◽  
Thorin Jonsson ◽  
Fernando Montealegre-Z
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Peak Frequency ◽  
Anatomical Location ◽  
Term Survival ◽  
Extinct Species ◽  
The Family ◽  
Predator Defence ◽  
Predator Evasion

The use of acoustics in predator evasion is a widely reported phenomenon amongst invertebrate taxa, but the study of ultrasonic anti-predator acoustics is often limited to the prey of bats. Here, we describe the acoustic function and morphology of a unique stridulatory structure in the relict orthopteran Cyphoderris monstrosa (Ensifera, Hagloidea): the Ander's organ. This species is one of just eight remaining members of the family Prophalangopsidae, a group with a fossil record of over 90 extinct species widespread during the Jurassic. We reveal that the sound produced by this organ has the characteristics of a broadband ultrasonic anti-predator defence, with a peak frequency of 58±15.5 kHz and a bandwidth of 50 kHz (at 10 dB below peak). Evidence from sexual dimorphism, knowledge on hearing capabilities and assessment of local predators, suggest the signal likely targets ground-dwelling predators. Additionally, we reveal a previously undescribed series of cavities underneath the organ that likely function as a mechanism for ultrasound amplification. Morphological structures homologous in both appearance and anatomical location to the Ander's organ are observed to varying degrees in 4 of the 7 other extant members of this family, with the remaining 3 yet to be assessed. Therefore, we suggest that such structures may either be more widely present in this ancient family than previously assumed, or have evolved to serve a key function in the long-term survival of these few species, allowing them to outlive their extinct counterparts.

scholarly journals Seasonal dynamics of dental sexual dimorphism in the Atlantic stingray Dasyatis sabina

1996 ◽  
Vol 199 (10) ◽  
pp. 2297-2306 ◽  
Author(s):  
S Kajiura ◽  
T Tricas
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Reproductive Season ◽  
Sexually Dimorphic ◽  
Mating Season ◽  
Selective Pressures ◽  
Dasyatis Sabina ◽  
Atlantic Stingray ◽  
Cartilaginous Fishes

Cartilaginous fishes continuously replace their teeth throughout their life (polyphyodonty) and often show a sexually dimorphic dentition that was previously thought to be an invariant sex character. Radial vector analysis of tooth shape in the polyphyodontic stingray Dasyatis sabina across a consecutive 24 month period shows a stable molariform morphology for females but a periodic shift in male dentition from a female-like molariform to a recurved cuspidate form during the reproductive season. The grip tenacity of the male dentition is greater for the cuspidate form that occurs during the mating season than for the molariform dentition that occurs during the non-mating season. Dental sexual dimorphism and its sex-dependent temporal plasticity probably evolved via polyphyodontic preadaptation under selective pressures on both sexes for increased feeding efficiency and sexual selection in males to maximize mating success. These phenomena are important considerations for the identification and classification of cartilaginous fishes and possibly other polyphyodontic vertebrates in the fossil record.

scholarly journals Sexual Dimorphism in the Gut Microbiome

2018 ◽  
Vol 4 (1) ◽  
pp. 12-16
Author(s):  
Clarissa Ren ◽  
Kristyn Sylvia
Keyword(s):  
Sex Differences ◽  
Sexual Dimorphism ◽  
Social Behavior ◽  
Gut Microbiome ◽  
Fine Tuning ◽  
Adult Males ◽  
Gut Microbes ◽  
Males And Females ◽  
And Behaviors ◽  
The Individual

The gut microbiome has received increasing interest in past years due to its link to many diseases and its potential in therapy. One often-overlooked and newer area of research is the sexual dimorphism in the gut microbiome, and how it relates to the sex differences in behavior, diseases, and the underlying makeup between that of males and females. Reviewing the literature has demonstrated that in several organisms, adult males and females do naturally have different compositions of gut microbes. Differences between the sexes in gut microbiome have also been correlated with differences between the sexes in social behavior and various disorders. A thorough understanding of sexual dimorphism in the gut microbiome is crucial to designing better studies, understanding the mechanism of the diseases and behaviors tied to the sexual dimorphism in the microbiome, and fine-tuning more precise treatments that account for the sex of the individual.

scholarly journals Evolution and extinction can occur rapidly: a modeling approach

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11130
Author(s):  
Vitaly A. Likhoshvai ◽  
Tamara M. Khlebodarova
Keyword(s):  
Sexual Dimorphism ◽  
Ecosystem Functioning ◽  
Fossil Record ◽  
Life Forms ◽  
Living Systems ◽  
Adaptive Diversification ◽  
Self Development ◽  
Emergence Of Life ◽  
Selection Of ◽  
Reproduction Efficiency

Fossil record of Earth describing the last 500 million years is characterized by evolution discontinuity as well as recurring global extinctions of some species and their replacement by new types, the causes of which are still debate. We developed a model of evolutionary self-development of a large ecosystem. This model of biota evolution based on the universal laws of living systems functioning: reproduction, dependence of reproduction efficiency and mortality on biota density, mutational variability in the process of reproduction and selection of the most adapted individuals. We have shown that global extinctions and phases of rapid growth and biodiversity stasis can be a reflection of the emergence of bistability in a self-organizing system, which is the Earth’s biota. Bistability was found to be characteristic only for ecosystems with predominant sexual reproduction. The reason for the transition from one state to another is the selection of the most adapted individuals. That is, we explain the characteristics of the Earth’s fossil record during the last 500 million years by the internal laws of Earth’s ecosystem functioning, which appeared at a certain stage of evolution as a result of the emergence of life forms with an increased adaptive diversification associated with sexual dimorphism.

The earliest fossil record of the wasp subfamily Pelecininae (Hymenoptera: Proctotrupoidea: Pelecinidae) from the Yixian Formation of China

Zootaxa ◽  
2009 ◽  
Vol 2080 (1) ◽  
pp. 47-54 ◽  
Author(s):  
CHENXI LIU ◽  
CHUNGKUN SHIH ◽  
DONG REN
Keyword(s):  
New Species ◽  
Sexual Dimorphism ◽  
Fossil Record ◽  
New Genus ◽  
Upper Jurassic ◽  
Yixian Formation ◽  
Liaoning Province ◽  
Wing Margin ◽  
The World ◽  
A New Species

A new genus with a new species (Shoushida regilla gen. et sp. nov.) of pelecinid wasps is described and illustrated. The fossil has been collected from the Upper Jurassic to Lower Cretaceous of Yixian Formation at Huangbanjigou Village, Liaoning Province, China. The new species has vein Rs forking to two branches: Rs 1 straight and reaching wing margin much before apex and Rs 2 long, forming an “X” pattern together with 2r-rs. This finding represents the earliest fossil record of subfamily Pelecininae in the world up to date. Sexual dimorphism in Pelecinidae is briefly discussed.

Recognizing sexual dimorphism in the fossil record: lessons from nonavian dinosaurs

Paleobiology ◽  
2017 ◽  
Vol 43 (3) ◽  
pp. 495-507 ◽  
Author(s):  
Jordan C. Mallon
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Statistical Tests ◽  
A Priori ◽  
Mixture Modeling ◽  
Statistical Investigation ◽  
Morphological Data ◽  
Sexually Dimorphic ◽  
Quantitative Evidence ◽  
Evolution Of Life

AbstractThe demonstration of sexual dimorphism in the fossil record can provide vital information about the role that sexual selection has played in the evolution of life. However, statistically robust inferences of sexual dimorphism in fossil organisms are exceedingly difficult to establish, owing to issues of sample size, experimental control, and methodology. This is particularly so in the case of dinosaurs, for which sexual dimorphism has been posited in many species, yet quantifiable data are often lacking. This study presents the first statistical investigation of sexual dimorphism across Dinosauria. It revisits prior analyses that purport to find quantitative evidence for sexual dimorphism in nine dinosaur species. After the available morphological data were subjected to a suite of statistical tests (normality and unimodality tests and mixture modeling), no evidence for sexual dimorphism was found in any of the examined taxa, contrary to conventional wisdom. This is not to say that dinosaurs were not sexually dimorphic (phylogenetic inference suggests they may well have been), only that the available evidence precludes its detection. A priori knowledge of the sexes would greatly facilitate the assessment of sexual dimorphism in the fossil record, and it is suggested that unambiguous indicators of sex (e.g., presence of eggs, embryos, medullary bone) be used to this end.

Sexual dimorphism in mid-Cretaceous silvanid beetles from northern Myanmar (Coleoptera, Silvanidae, Brontinae)

2019 ◽  
Vol 2 (3) ◽  
pp. 289-296 ◽  
Author(s):  
CHENYANG CAI ◽  
DIYING HUANG
Keyword(s):  
Sexual Dimorphism ◽  
Small Group ◽  
Fossil Record ◽  
Female Genitalia ◽  
Burmese Amber ◽  
Male And Female ◽  
Morphological Variations ◽  
Limited Sampling ◽  
Morphological Convergence ◽  
Dead Trees

Silvanidae is a small group of cucujoid beetles, and their fossil record is poorly documented. The two recently described genera from Burmese amber, Cretoliota Liu et al. and Protoliota Liu et al., are distinctive among all known Silvanidae, displaying markedly long antennae and mandibular horns in males, as found in the extant Uleiota Latreille. Due to the limited sampling of fossil specimens, the morphological variations of male mandibular horns remain a mystery. Here we report six well-preserved specimens of Protoliota with both male and female genitalia exposed from mid-Cretaceous Burmese amber. Our discovery confirms the presence of remarkable sexual dimorphism in Protoliota. Males of Protoliota antennatus Liu et al. display short to very long mandibular horns and much longer antennae. Interesting morphological convergence of the beetles (Silvanidae and Staphylinidae) living under the bark of dead trees is briefly discussed. Our discovery represents the first definitive sexual dimorphism in beetles from Burmese amber.

scholarly journals A Reevaluation of Sexual Dimorphism in the Postcranium of the Chasmosaurine Ceratopsid Chasmosaurus belli (Dinosauria: Ornithischia)

2006 ◽  
Vol 120 (4) ◽  
pp. 403 ◽  
Author(s):  
Jordan C. Mallon ◽  
Robert B. Holmes
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Statistical Significance ◽  
Separate Species ◽  
Moderate Amount ◽  
Show Evidence ◽  
Dinosaur Park Formation

The sexual dimorphism attributed to Chasmosaurus belli by Sternberg (1927) is revisited and reevaluated. A reexamination of the two specimens originally considered by Sternberg reveals that they are less complete than first suggested, with only a moderate amount of overlapping material between them. Only a few of the postcranial elements (humeri, sternal plates, and presacral vertebrae) show evidence of dimorphism, the significance of which is either doubtful or equivocal. Instead of representing sexual dimorphs, it is likely that the two specimens belong to separate species, C. belli and C. russelli, as evidenced by their distinct frill morphologies and by their stratigraphic segregation within the Dinosaur Park Formation of Alberta. These findings emphasize the need to remain sceptical about claims advocating sexual dimorphism in the fossil record in the absence of statistical significance or stratigraphic control.

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