scholarly journals Morphometric Correlates of Age and Breeding Status in American Coots

The Auk ◽  
1987 ◽  
Vol 104 (4) ◽  
pp. 640-646 ◽  
Author(s):  
Ray T. Alisauskas
Keyword(s):  
Body Size ◽  
Multivariate Techniques ◽  
Same Sex ◽  
Linear Measurements ◽  
Morphometric Variation ◽  
Size And Shape ◽  
Multivariate Dispersion ◽  
Age Related ◽  
The Social ◽  
Males And Females

Abstract I studied morphometric variation in 13 linear measurements from 228 American Coots (Fulica americana) collected in southern Manitoba. Univariate and multivariate techniques revealed differences in size and shape among adult coots that were 1, 2, and =2 yr old. In addition to the obvious differences in size between males and females, the morphometry of older birds differed from that of younger birds in two ways. First, older coots were of larger body size than younger coots of the same sex. Second, older coots had proportionately larger feet and claws relative to the size of their tarsi, and proportionately wider bills and heads relative to other head measurements, than did younger birds. Multivariate dispersion matrices within age/sex cohorts were less variable for older coots. In an analysis of 1-yr-old males, breeders did not differ from nonbreeders in overall body size, but breeders had relatively longer claws and wings than nonbreeders. Age-related differences in morphology may have relevance to the social structure of nesting coots, which involves highly aggressive territorial behavior. Part of the age-related variation in nesting phenology that has been documented elsewhere for coots may be a consequence of covariation in body size and shape.

Heads up: sexual dimorphism in house crickets (Acheta domesticus)

2008 ◽  
Vol 86 (4) ◽  
pp. 253-259 ◽  
Author(s):  
Sean E. Walker ◽  
J. Andrew Roberts ◽  
Israel Adame ◽  
Corey J. Collins ◽  
Daniel Lim
Keyword(s):  
Sex Differences ◽  
Body Size ◽  
Visual Display ◽  
Acheta Domesticus ◽  
Head Size ◽  
Visual Signal ◽  
Linear Measurements ◽  
Geometric Morphometric ◽  
Differential Selection ◽  
Males And Females

Many species are sexually dimorphic because of differential selection on each sex. In many species, males tend to have exaggerated traits or larger body size compared with females. In house crickets ( Acheta domesticus L., 1758), the males defend resources and compete for mates by engaging in a striking visual display sequence that includes mandible flaring, where males spread their mandibles wide open. This behavior presumably acts only in males as a visual signal of body size and as an indicator of the willingness to fight, as females do not exhibit this behavior. We tested the hypothesis that sex differences in the signals used for aggressive interactions will lead to sex differences in the morphology of the head in house crickets. To test this hypothesis we made linear measurements of body and head sizes on males and females and utilized geometric morphometric methods to reconstruct sex differences in shape. We also compared the total pigmented area of the faces of males and females. Males had larger heads with proportionally more pigmented area than females and there were significant shape differences. In addition, allometric relationships between head size and body size indicated that head size increases faster than body size in males. Geometric morphometric analysis indicated that the shape differences result in an exaggeration of the mandibular area in males compared with females. These data suggest that the differential selection acting on males and females can lead to differences in size, shape, and pigmentation related to signal structure and function.

scholarly journals Young chicks quickly lose their spontaneous preference to aggregate with females

2020 ◽  
Author(s):  
Virginia Pallante ◽  
Daniele Rucco ◽  
Elisabetta Versace
Keyword(s):  
Sex Discrimination ◽  
Phasianus Colchicus ◽  
Same Sex ◽  
Experimental Protocol ◽  
Male And Female ◽  
Sex Preference ◽  
Initial Preference ◽  
The Social ◽  
Males And Females ◽  
Young Chicks

AbstractIt is not clear when and how animals start to discriminate between male and female conspecifics and how this distinction drives their social behaviour. A recent study on pheasants found that one-week-old chicks (Phasianus colchicus) preferentially aggregated with same-sex peers and this trend became more pronounced through development, suggesting that sexual segregation increases during ontogeny. However, it remains unclear whether this ability depends on experience or develops spontaneously. Using a similar experimental protocol, we investigated whether sex discrimination is present at birth in domestic chickens (Gallus gallus) by testing the aggregation preferences of young chicks with clutch mates. We measured the amount of time spent close to male and female conspecifics in visually inexperienced chicks. Soon after hatching, both males and females preferentially aggregated with females. To clarify whether the experience with conspecifics modifies the initial preference for females we used an imprinting procedure. We exposed chicks to conspecifics of the same sex, different sex or both sexes for three days and then tested their preferences to aggregate with males or females. No sex preference was observed after three days of imprinting exposure. The disappearance of the initial sex preference shows that, although chicks can discriminate between conspecifics of different sex, sex segregation does not influence aggregation in the first week of life. We suggest that the absence of sexual assortment in the first week of age can enhance the social cohesion of the flock.

scholarly journals Inbreeding removes sex differences in lifespan in a population of Drosophila melanogaster

2016 ◽  
Vol 12 (6) ◽  
pp. 20160337 ◽  
Author(s):  
Pau Carazo ◽  
Jared Green ◽  
Irem Sepil ◽  
Tommaso Pizzari ◽  
Stuart Wigby
Keyword(s):  
Sex Differences ◽  
Drosophila Melanogaster ◽  
Evolutionary Biology ◽  
Social Effects ◽  
Same Sex ◽  
Deleterious Alleles ◽  
The Social ◽  
Specific Mortality ◽  
Males And Females ◽  
Female Lifespan

Sex differences in ageing rates and lifespan are common in nature, and an enduring puzzle for evolutionary biology. One possibility is that sex-specific mortality rates may result from recessive deleterious alleles in ‘unguarded’ heterogametic X or Z sex chromosomes (the unguarded X hypothesis). Empirical evidence for this is, however, limited. Here, we test a fundamental prediction of the unguarded X hypothesis in Drosophila melanogaster , namely that inbreeding shortens lifespan more in females (the homogametic sex in Drosophila ) than in males. To test for additional sex-specific social effects, we studied the lifespan of males and females kept in isolation, in related same-sex groups, and in unrelated same-sex groups. As expected, outbred females outlived outbred males and inbreeding shortened lifespan. However, inbreeding-mediated reductions in lifespan were stronger for females, such that lifespan was similar in inbred females and males. We also show that the social environment, independent of inbreeding, affected male, but not female lifespan. In conjunction with recent studies, the present results suggest that asymmetric inheritance mechanisms may play an important role in the evolution of sex-specific lifespan and that social effects must be considered explicitly when studying these fundamental patterns.

Influence of Same-Sex and Mixed-Sex Exercise Settings on the Social Physique Anxiety and Exercise Intentions of Males and Females

2004 ◽  
Vol 26 (4) ◽  
pp. 616-622 ◽  
Author(s):  
L. Darren Kruisselbrink ◽  
Ann M. Dodge ◽  
Sherry L. Swanburg ◽  
Amanda L. MacLeod
Keyword(s):  
Negative Impact ◽  
Exercise Behavior ◽  
Social Physique Anxiety ◽  
Same Sex ◽  
Female Fitness ◽  
Male And Female ◽  
The Social ◽  
Males And Females

Situational social physique anxiety (SPA) and immediate exercise intentions in male and female fitness club members were examined in response to all-female, all-male, and mixed-sex exercise setting scenarios. Overall, women showed higher levels of situational SPA than men. SPA increased significantly from an all-female, to a mixed-sex, to an all-male exercise setting for women but not for men. More women indicated they would shorten their workout in response to the all-male vs. all-female or mixed-sex exercise scenarios. For all-male and mixed-sex scenarios, participants who intended to shorten their workout also tended to report higher situational SPA scores. The results indicate that the presence of men in an exercise setting stimulates physique anxiety in women, and that exercising in an all-female environment may have the least negative impact on the exercise behavior of women.

Sexual size and shape dimorphism in the Near Eastern fire salamander, Salamandra infraimmaculata (Caudata: Salamandridae)

2017 ◽  
Vol 67 (1) ◽  
pp. 29-40 ◽  
Author(s):  
Abdullah Altunışık
Keyword(s):  
Body Size ◽  
Life History Traits ◽  
Leg Length ◽  
Near Eastern ◽  
Size And Shape ◽  
Significant Difference ◽  
Fire Salamander ◽  
Males And Females ◽  
Body Shapes ◽  
And Behavior

Sexual dimorphism, phenotypic difference between males and females of the same species, has been demonstrated in many invertebrates and vertebrates. In many of these studies, which were especially conducted on amphibians, female individuals were reported to be larger than males. However, this does not necessarily mean that this also applies to body shapes. Therefore, in this study, a total of 31 characters of body size and body shape were measured and analyzed in the Near Eastern fire salamander, in order to understand whether these characters differ between female and male individuals. The results suggest that there is a significant difference between the sexes in terms of both body size and some body shapes (e.g. arm and leg length, arm diameter, cloacal proportions) in this fire salamander. I conclude that both sexual size and shape dimorphism need to be taken into account to help understand an organism’s life-history traits, ecology, population dynamics and behavior.

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 Estimating Craniofacial Growth Cessation: Comparison of Asymptote- and Rate-Based Methods

2021 ◽  
pp. 105566562110026
Author(s):  
Anna M. Hardin ◽  
Ryan P. Knigge ◽  
Hee Soo Oh ◽  
Manish Valiathan ◽  
Dana L. Duren ◽  
...  
Keyword(s):  
Estimation Method ◽  
Logistic Models ◽  
Careful Consideration ◽  
Craniofacial Growth ◽  
Craniofacial Anomalies ◽  
Linear Measurements ◽  
Growth Cessation ◽  
Lateral Cephalograms ◽  
Males And Females ◽  
Important Milestone

Objective: To identify differences between asymptote- and rate-based methods for estimating age and size at growth cessation in linear craniofacial measurements. Design: This is a retrospective, longitudinal study. Five linear measurements were collected from lateral cephalograms as part of the Craniofacial Growth Consortium Study (CGCS). Four estimates of growth cessation, including 2 asymptote- (GCasym, GCerr) and 2 rate-based (GCabs, GC10%) methods, from double logistic models of craniofacial growth were compared. Participants: Cephalometric data from participants in 6 historic longitudinal growth studies were included in the CGCS. At least 1749 individuals (870 females, 879 males), unaffected by craniofacial anomalies, were included in all analyses. Individuals were represented by a median of 11 images between 2.5 and 31.3 years of age. Results: GCasym consistently occurred before GCerr and GCabs consistently occurred before GC10% within the rate-based approaches. The ordering of the asymptote-based methods compared to the rate-based methods was not consistent across measurements or between males and females. Across the 5 measurements, age at growth cessation ranged from 13.56 (females, nasion-basion, GCasym) to 24.39 (males, sella-gonion, GCerr). Conclusions: Adolescent growth cessation is an important milestone for treatment planning. Based on our findings, we recommend careful consideration of specific definitions of growth cessation in both clinical and research settings since the most appropriate estimation method may differ according to patients’ needs. The different methods presented here provide useful estimates of growth cessation that can be applied to raw data and to a variety of statistical models of craniofacial growth.

scholarly journals Friends’ influence on the development of academic values in mathematics: are there differences between female and male dyads?

2020 ◽  
Author(s):  
Marion Reindl ◽  
Burkhard Gniewosz ◽  
Markus Dresel
Keyword(s):  
Longitudinal Study ◽  
Social Cognitive Theory ◽  
Social Cognitive ◽  
Cognitive Theory ◽  
Intrinsic Value ◽  
Same Sex ◽  
Academic Values ◽  
Final Sample ◽  
The Social ◽  
Other Regarding

Abstract Based on the social cognitive theory and the emotional contagion theory, this study investigated if friends influence (reinforce or change) the development of academic values (intrinsic value, emotional cost) and if this process differs across same-sex friendship dyads. We drew on data collected in a two-wave longitudinal study in Germany. The final sample was based on 264 stable reciprocated friendship dyads of grades 5 and 7 (148 female dyads and 116 male dyads). Results of actor-partner-interdependence models indicated that friends reinforce each other regarding the intrinsic value and initiate change regarding the emotional cost. Moreover, female and male friendship dyads did not differ in the strength of influence on academic values. Results were discussed in terms of selection and socialization effects regarding friendships.

Dispersal patterns in a regional koala population in south-east Queensland

2003 ◽  
Vol 30 (3) ◽  
pp. 281 ◽  
Author(s):  
David S. Dique ◽  
Jim Thompson ◽  
Harriet J. Preece ◽  
Deidré L. de Villiers ◽  
Frank N. Carrick
Keyword(s):  
Urban Areas ◽  
Home Ranges ◽  
Adult Males ◽  
Dispersal Patterns ◽  
Young Males ◽  
Straight Line ◽  
The Social ◽  
Straight Line Distance ◽  
Males And Females ◽  
Natal Home

Koala dispersal was investigated as part of a detailed ecological study of a nationally significant koala population located 20 km south-east of Brisbane, Queensland. From 1996 to 2000, 195 koalas from three sites were captured and fitted with radio-collars. A total of 40 koalas (23 males and 17 females) dispersed from these sites. Most (93%) dispersing individuals were 20–36 months of age. Three adult females (more than 36 months old) dispersed and no adult males dispersed during the study. A significantly higher proportion of young males dispersed than females. Dispersal occurred between June and December, with most dispersal of males commencing in July and August and that of females commencing between September and November prior to, and early in, the annual breeding season. The mean straight-line distance between the natal and breeding home ranges for males and females was similar and was measured at 3.5 km (range 1.1–9.7 km) and 3.4 km (range 0.3–10.6 km) respectively. Dispersing males and females tended to successfully disperse south and west of their natal home ranges and were generally unable to successfully disperse to urban areas within the study area, as a high proportion of the mortality of dispersing koalas was associated with attacks by domestic dogs and with collisions with vehicles on roads. Information from other studies indicates that most young koalas disperse from their natal areas. It is likely that the social behaviour and mating systems of koala populations provide mechanisms for young koalas to disperse. The potential role of dispersal in the dynamics of regional koala populations is discussed.

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