scholarly journals Sexual behaviour and morphological variation in the millipede Megaphyllum bosniense (Verhoeff, 1897)

2018 ◽  
Vol 87 (3) ◽  
pp. 133-148
Author(s):  
Vukica Vujić ◽  
Bojan Ilić ◽  
Zvezdana Jovanović ◽  
Sofija Pavković-Lučić ◽  
Sara Selaković ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Behaviour ◽  
Morphological Variation ◽  
Morphological Traits ◽  
Morphological Evolution ◽  
Random Mating ◽  
Mate Preferences ◽  
Linear Measurements ◽  
Time Duration ◽  
Sexual Selection Theory

Sexual selection can be a major driving force that favours morphological evolution at the intraspecific level. According to the sexual selection theory, morphological variation may accompany non-random mating or fertilization. Here both variation of linear measurements and variation in the shape of certain structures can significantly influence mate choice in different organisms. In the present work, we quantified sexual behaviour of the millipede Megaphyllum bosniense (Verhoeff, 1897) as characterized by several sequences. These are: mating latency, duration of copulation, contact to copulation time, duration of contact without copulation, time from entrance (time-point when individuals were placed in boxes in which tests occurred) to contact with copulation, and time from entrance to contact without copulation. Further, we analysed the influence of morphological variation (both variation of linear measurements and variation in the shape of several structures) on mating success. Variation of body length, antennal length, length of the walking legs, trunk width, and trunk height was analysed by traditional morphometrics, while variation in size and shape of the antennae, walking legs, head, and gonopods (promeres, opisthomeres) was analysed using geometric morphometrics. More than half of all physical contacts detected among the millipedes resulted in copulation. Based on the value of sexual selection coefficients, preferences toward the previous partner were found to be prevalent in both female and male choice tests. Individuals with different mating status significantly differed in some morphological traits (body mass, head centroid size, head shape, and promere shape). Our study yielded new information about the sexual behaviour of millipedes and variation of morphological traits as a potential basis for mate preferences.

scholarly journals Habitat, Sexual and Allometric Influences on Morphological Traits of Intertidal Crabs

2020 ◽  
Author(s):  
P. Vermeiren ◽  
C. Lennard ◽  
C. Trave
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Morphological Variation ◽  
Morphological Traits ◽  
Low Cost ◽  
Habitat Preferences ◽  
Mangrove Crab ◽  
Habitat Factors ◽  
Specific Factors ◽  
Claw Shape

Abstract Intertidal crabs display distinct morphological traits that allow differential interactions with biotic and abiotic features of the intertidal landscape, but are also influenced by allometry and sexual selection. This study aimed to explore the influence of sexual, allometric and habitat factors on morphological variation in the intertidal mangrove crab assemblage. A standardized photographic protocol was developed using readily available, low-cost technology to capture the morphology of carapaces and claws as sets of Cartesian landmarks. Digitization errors were 1 to 2 orders of magnitude smaller than the variation among individuals. In Tubuca seismella and Tubuca signata (superfamily Ocypodoidea), species that have traditionally been studied for sexual dimorphism, standardized major claw sizes were 2.8 and 3.7, respectively, times larger for males than females. Sexual dimorphism in claw size was also observed for Metopograpsus frontalis and Parasesarma longicristatum (superfamily Grapsoidea), with the largest claw in males being 15% and 33%, respectively, larger than in females. In contrast to size, claw shape did not relate to sex, except for T. seismella. Carapace shape, although variable among individuals and displaying asymmetry, was unrelated to sex. Claw and carapace shapes displayed high correlations, with values around 0.78. Carapace shapes grouped into taxonomic families and linked to habitat preferences, while claw shapes varied along a taxonomic gradient. These results complement studies on crab morphology that focus on specific factors or species, and stress the importance of multiple, interacting factors including sexual, allometric and habitat influences as drivers of morphological trait variability.

scholarly journals Intelligence can be detected but is not found attractive in videos and live interactions

2020 ◽  
Author(s):  
Julie Christin Driebe ◽  
Morgan Sidari ◽  
Michael Dufner ◽  
Juliane M. von der Heiden ◽  
Paul - Christian Bürkner ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Physical Attractiveness ◽  
Mate Preferences ◽  
Selection Theory ◽  
Theory Of Intelligence ◽  
Video Clips ◽  
Self Reports ◽  
Sexual Selection Theory ◽  
Short Video ◽  
Initial Attraction

Humans’ extraordinary intelligence seems to extend beyond the needs for survival. One theory to explain this surplus intelligence is that it evolved via sexual selection as a fitness indicator to advertise genetic quality to prospective mates. Consistent with this idea, self-reported mate preferences suggest intelligence is valued across cultures. Yet, as the validity of these self-reports has been questioned, it remains unclear whether objectively assessed intelligence is indeed attractive. We analysed data from two studies to test this key premise of the sexual selection theory of intelligence. In Study 1, 88 target men had their intelligence measured and based on short video clips were rated on intelligence, funniness, physical attractiveness and mate appeal by 179 women. In Study 2 (N = 729), participants took part in 2 to 5 speed-dating sessions in which their intelligence was measured and they rated each other’s intelligence, funniness, and mate appeal. Measured intelligence did not predict increased mate appeal in either study, whereas perceived intelligence and funniness did. More intelligent people were perceived as more intelligent, but not as funnier. Results suggest that intelligence is not important for initial attraction, which raises doubts concerning the sexual selection theory of intelligence.

scholarly journals Testing Mate Choice Hypotheses in a Transitional Small Scale Population

2021 ◽  
Author(s):  
Lynda Boothroyd ◽  
Jean-Luc Jucker ◽  
Tracey Thornborrow ◽  
Martin Tovee ◽  
Carlota Batres ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Demographic Data ◽  
Mate Preferences ◽  
Small Scale ◽  
Sexually Dimorphic ◽  
Facial Structure ◽  
Scale Population ◽  
Sexual Selection Theory ◽  
Objective Tests

Objective: Tests of theories of mate choice often rely on data gathered in White, industrialised samples and this is especially the case for studies of facial attraction. Our understanding of preferences for sexual dimorphism is currently in flux and a number of hypotheses require testing in more diverse participant samples. The current study uses opportunistically gathered facial dimorphism preference data from c. 300 participants in rural Nicaragua. We assess hypotheses drawn from sexual selection theory, and from more recent approaches which consider the impacts of economic development and cultural ‘modernisation’ on mate preferences. Methods: Participants verbally reported demographic data, and indicated preferences for five male and five female pairs of faces manipulated to differ in sexually dimorphic facial structure based on a sample of Salvadoran individuals.Results and conclusions: Pending

scholarly journals Pattern and pace of morphological change due to variable human impact: the case of Japanese macaques

Primates ◽  
2021 ◽  
Author(s):  
Madeleine Geiger
Keyword(s):  
Body Size ◽  
Human Impact ◽  
Morphological Variation ◽  
Japanese Macaques ◽  
Linear Measurements ◽  
Skull Shape ◽  
Rates Of Change ◽  
Animal Populations ◽  
Captive Populations ◽  
In Captivity

AbstractHuman impact influences morphological variation in animals, as documented in many captive and domestic animal populations. However, there are different levels of human impact, and their influence on the pattern and rate of morphological variation remains unclear. This study contributes to the ongoing debate via the examination of cranial and mandibular shape and size variation and pace of change in Japanese macaques (Macaca fuscata). This species is ideal for tackling such questions because different wild, wild-provisioned, and captive populations have been monitored and collected over seven decades. Linear measurements were taken on 70 skulls from five populations, grouped into three ‘human impact groups’ (wild, wild-provisioned, and captive). This made it possible to investigate the pattern and pace of skull form changes among the human impact groups as well as over time within the populations. It was found that the overall skull shape tends to differ among the human impact groups, with captive macaques having relatively longer rostra than wild ones. Whether these differences are a result of geographic variation or variable human impact, related to nutritional supply and mechanical properties of the diet, is unclear. However, this pattern of directed changes did not seem to hold when the single captive populations were examined in detail. Although environmental conditions have probably been similar for the two examined captive populations (same captive locality), skull shape changes over the first generations in captivity were mostly different. This varying pattern, together with a consistent decrease in body size in the captive populations over generations, points to genetic drift playing a role in shaping skull shape and body size in captivity. In the captive groups investigated here, the rates of change were found to be high compared to literature records from settings featuring different degrees of human impact in different species, although they still lie in the range of field studies in a natural context. This adds to the view that human impact might not necessarily lead to particularly fast rates of change.

scholarly journals Darwin's bawdy: the popular, gendered and radical reception of the Descent of Man in the US, 1871–1910

BJHS Themes ◽  
2021 ◽  
pp. 1-17
Author(s):  
Kimberly A. Hamlin
Keyword(s):  
Sexual Selection ◽  
Selection Theory ◽  
Scientific Establishment ◽  
Scientific Institutions ◽  
The Us ◽  
Sexual Selection Theory ◽  
Descent Of Man

Abstract Most studies of the American reception of Darwin have focused on the Origin. The Descent of Man, however, was even more widely read and discussed, especially by those outside the emerging scientific establishment. This essay maps the varied, popular and radical responses to the Descent and suggests that these unauthorized readers helped shape the formation of American scientific institutions (by encouraging scientists to close ranks), as well as ordinary Americans’ perceptions of gender and sex. I argue that the radical – freethinkers, socialists and feminists – embrace of sexual selection theory provides one explanation for naturalists’ scepticism of the theory.

More sires may enhance offspring fitness in Northern Map Turtles (Graptemys geographica)

2013 ◽  
Vol 91 (8) ◽  
pp. 581-588 ◽  
Author(s):  
Nicola Banger ◽  
Gabriel Blouin-Demers ◽  
Grégory Bulté ◽  
Stephen C. Lougheed
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Hatching Success ◽  
Locomotor Performance ◽  
Conservative Estimate ◽  
Genetic Quality ◽  
Offspring Fitness ◽  
Sexual Selection Theory ◽  
Map Turtles ◽  
Graptemys Geographica

Sexual selection theory predicts that males should be promiscuous to maximize their reproductive success, while females should be choosy. Yet females of many taxa often produce progeny sired by multiple males, indicating that promiscuity can be important for the reproductive success of females. Promiscuity may enhance the fitness of females if it increases the genetic quality, or the genetic variety, and thus the viability of their offspring. We quantified the number of sires per clutch in a population of Northern Map Turtles (Graptemys geographica (LeSueur, 1817)) in Lake Opinicon, Ontario, Canada, and tested whether the number of sires affects several metrics of viability in hatchlings. Based on the most conservative estimate, at least 71% of clutches in this population are sired by multiple males, but there was no evidence that larger clutches are sired by more males. Clutches sired by more males had higher hatching success and survival, but the differences were not statistically significant. We did not find any effect of the number of sires on hatchling morphology or locomotor performance. Collectively, our results partially support the hypothesis that promiscuity can increase the reproductive success of female Northern Map Turtles.

scholarly journals Evolutionary insight from a humble fly: sperm competition and the yellow dungfly

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200062
Author(s):  
Leigh W. Simmons ◽  
Geoff A. Parker ◽  
David J. Hosken
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Paradigm Shift ◽  
Mate Guarding ◽  
Reproductive Behaviour ◽  
Costs And Benefits ◽  
Theme Issue ◽  
Male And Female ◽  
Sexual Selection Theory ◽  
The 1960S

Studies of the yellow dungfly in the 1960s provided one of the first quantitative demonstrations of the costs and benefits associated with male and female reproductive behaviour. These studies advanced appreciation of sexual selection as a significant evolutionary mechanism and contributed to the 1970s paradigm shift toward individual selectionist thinking. Three behaviours in particular led to the realization that sexual selection can continue during and after mating: (i) female receptivity to remating, (ii) sperm displacement and (iii) post-copulatory mate guarding. These behaviours either generate, or are adaptations to sperm competition, cryptic female choice and sexual conflict. Here we review this body of work, and its contribution to the development of post-copulatory sexual selection theory. This article is part of the theme issue ‘Fifty years of sperm competition’.

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