Sexual dimorphism in leg length among orb-weaving spiders: a possible role for sexual cannibalism

Investigations of millipede mating dynamics have focussed primarily on Old World or North American species. In contrast, data for the diverse and abundant polydesmid millipedes of Australia are lacking. Here I examine copulation, behaviour and sexual dimorphism in an Australian millipede, Cladethosoma clarum. In this species, copula position is best described as ‘in parallel’. Both females and males mated with two or more individuals of the opposite sex, and average copulation duration was 4.7 min. Behavioural observations revealed differences between the sexes in patterns of behaviour. Specifically, females devoted most of their time to feeding, whereas males were more mobile and were observed walking more often than females. The sexes also exhibited marked sexual dimorphism in that females exhibited greater body width and body mass compared with males, whereas males had longer legs relative to females. In millipedes, longer legs allow an individual to walk faster. Consequently, male C. clarum appear to be capable of relatively rapid locomotion. As Australian millipede densities are spatially unpredictable, the increased mobility of males likely reflects an active mate-location strategy. Furthermore, the occurrence of multiple mating by females suggests that male leg length may have evolved as an adaptation for rapid mate location under scramble competition polygyny.

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Sexual dimorphism and allometry in the giant water strider Gigantometra gigas

Canadian Journal of Zoology ◽

10.1139/z99-071 ◽

1999 ◽

Vol 77 (6) ◽

pp. 923-929 ◽

Cited By ~ 23

Author(s):

Michelle Tseng ◽

Locke Rowe

Keyword(s):

Body Size ◽

Sexual Dimorphism ◽

Body Length ◽

Total Body Length ◽

Correlated Response ◽

Water Strider ◽

Leg Length ◽

Allometric Analysis ◽

Total Leg ◽

Total Body

This study describes sexual dimorphism in size (total body length and lengths of leg components) and in the allometric relationships between leg-component lengths and total body length in the giant water strider Gigantometra gigas (Heteroptera: Gerridae). Gigantometra gigas is the largest known gerrid, and has been previously described as monomorphic for body size. We compare our results with analogous data collected on Gerris buenoi, a species of more moderate size, where females are larger than males. Based on 94 specimens of G. gigas, we conclude that males are larger than females in all measured traits. This dimorphism was most spectacular in the leg components, which are 10-50% longer in males than in females. Males are generally more variable in size than females, and this is especially so for leg components. Allometric analysis suggests that total leg lengths (particularly middle and rear) increase at a much greater rate with body size in males than in females, therefore there is sexual dimorphism in allometries on the scale of that in the traits themselves. The relationship between middle and hind leg lengths is strong in both sexes, and appears to differ very little between the sexes or between G. gigas, and Ge. buenoi. These data suggest a constraint on this relationship, perhaps because of the biomechanics of locomotion. We propose that sexual selection acting on middle leg lengths in males explains both the increase and variance in middle leg length, and that hind leg length follows by correlated response.

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Sexual dimorphism in the Arachnid orders

PeerJ ◽

10.7717/peerj.5751 ◽

2018 ◽

Vol 6 ◽

pp. e5751 ◽

Cited By ~ 7

Author(s):

Callum J. McLean ◽

Russell J. Garwood ◽

Charlotte A. Brassey

Keyword(s):

Sexual Dimorphism ◽

Body Shape ◽

Sexual Size Dimorphism ◽

Future Research ◽

Sexually Dimorphic ◽

Leg Length ◽

Animal Kingdom ◽

Males And Females ◽

Total Body ◽

Insight Into

Sexual differences in size and shape are common across the animal kingdom. The study of sexual dimorphism (SD) can provide insight into the sexual- and natural-selection pressures experienced by males and females in different species. Arachnids are diverse, comprising over 100,000 species, and exhibit some of the more extreme forms of SD in the animal kingdom, with the males and females of some species differing dramatically in body shape and/or size. Despite this, research on arachnid SD has primarily focused on specific clades as opposed to observing traits across arachnid orders, the smallest of which have received comparatively little attention. This review provides an overview of the research to date on the trends and potential evolutionary drivers for SD and sexual size dimorphism (SSD) in individual arachnid orders, and across arachnids as a whole. The most common trends across Arachnida are female-biased SSD in total body size, male-biased SSD in relative leg length and SD in pedipalp length and shape. However, the evolution of sexually dimorphic traits within the group is difficult to elucidate due to uncertainty in arachnid phylogenetic relationships. Based on the dataset we have gathered here, we highlight gaps in our current understanding and suggest areas for future research.

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Sexual dimorphism in the olfactory lobes of moths: functional organization and development

Neuroscience Research ◽

10.1016/s0168-0102(00)80864-0 ◽

2000 ◽

Vol 38 ◽

pp. S1

Author(s):

J Hildebrand

Keyword(s):

Sexual Dimorphism ◽

Functional Organization

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Total Knee Arthroplasty after Previous Ipsilateral Hip Arthroplasty Showed Lower Clinical Outcomes and Higher Leg Length Discrepancy Perception

The Journal of Knee Surgery ◽

10.1055/s-0040-1715447 ◽

2020 ◽

Author(s):

Han-Jun Lee ◽

Seong Hwan Kim ◽

Nicolas Pujol ◽

Yong-Beom Park

Keyword(s):

Clinical Outcomes ◽

Hip Arthroplasty ◽

Leg Length ◽

Function Score ◽

Patient’S Satisfaction ◽

Length Discrepancy ◽

Total Knee ◽

Group 2 ◽

Ks Function ◽

Group 1

AbstractThe purpose of this study is to compare perception of leg length discrepancy (LLD) and clinical results of total knee arthroplasties (TKA) in patients with or without previous ipsilateral hip arthroplasty. Between 2008 and 2015, navigation-assisted TKA was performed in 43 patients with previous hip arthroplasty after hip fracture. After 1:3 propensity score matching was performed, 108 patients of primary navigation-assisted TKA (group 1) and 36 patients with hip arthroplasty (group 2) were included. Knee Society (KS) scores, Western Ontario and McMaster Universities Index (WOMAC) scores, and patients' satisfaction including perception of LLD were evaluated. Radiographic evaluation included mechanical axis, component position, and LLD. Logistic regression analysis was performed to find the factors that affect the clinical outcomes. No significant differences in radiologic and clinical evaluations, except for KS function score, patient's satisfaction and LLD (p< 0.001), were detected between the groups. LLD and its perception were significantly higher in group 2 (1.8 ± 3.4 mm in group 1 and 9.7 ± 4.1 mm in group 2, p = 0.000). Risk factors for the low KS function score were found as LLD (odds ratio [OR]: 1.403, p = 0.008) and previous hip arthroplasty itself (OR: 15.755, p = 0.002), but much higher OR was found in previous hip arthroplasty. Although the outcomes of TKA in patients with ipsilateral hip arthroplasty are comparable to those of primary TKA, LLD was high and patient's satisfaction and functional outcomes were low in patients with previous ipsilateral hip arthroplasty. Care should be taken when considering TKA in patients with previous hip arthroplasty. This is a Level III, case control study.

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RHYNCHOLITES AND THE PROBLEM OF NARROW AND BROAD CONCEPTION OF TAXONS

Proceedings of higher educational establishments Geology and Exploration ◽

10.32454/0016-7762-2018-1-12-17 ◽

2018 ◽

pp. 12-17 ◽

Cited By ~ 3

Author(s):

I. R. Khuzina ◽

V. N. Komarov

Keyword(s):

Sexual Dimorphism ◽

Morphological Characteristics ◽

Mass Scale ◽

Individual Variability ◽

Point Of View ◽

The Other ◽

New Taxon ◽

Artificial System ◽

Broad Understanding

The paper considers a point of view, based on the conception of the broad understanding of taxons. According to this point of view, rhyncholites of the subgenus Dentatobeccus and Microbeccus are accepted to be synonymous with the genus Rhynchoteuthis, and subgenus Romanovichella is considered to be synonymous with the genus Palaeoteuthis. The criteria, exercising influence on the different approaches to the classification of rhyncholites, have been analyzed (such as age and individual variability, sexual dimorphism, pathological and teratological features, degree of disintegration of material), underestimation of which can lead to inaccuracy. Divestment of the subgenuses Dentatobeccus, Microbeccus and Romanovichella, possessing very bright morphological characteristics, to have an independent status and denomination to their synonyms, has been noted to be unjustified. An artificial system (any suggested variant) with all its minuses is a single probable system for rhyncholites. The main criteria, minimizing its negative sides and proving the separation of the new taxon, is an available mass-scale material. The narrow understanding of the genus, used in sensible limits, has been underlined to simplify the problem of the passing the view about the genus to the other investigators and recognition of rhyncholites for the practical tasks.

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Observation on the breeding biology of Polypedates teraiensis (Dubois, 1987) (Amphibia: Rhacophoridae)

Science Vision ◽

10.33493/scivis.17.01.05 ◽

2017 ◽

Vol 17 (1) ◽

pp. 25-32

Author(s):

Jacinta Lalchhanhimi ◽

Lalremsanga H.T.

Keyword(s):

Sexual Dimorphism ◽

Breeding Season ◽

Sound Production ◽

Reproductive Function ◽

Breeding Biology ◽

Tree Frog ◽

University Campus ◽

Morphometric Measurements ◽

Advertisement Calls ◽

Males And Females

The breeding biology of tree frog, Polypedates teraiensis was studied during the breeding season at Mizoram University Campus. It was found that sound production by male during the breeding season was primarily a reproductive function and advertisement calls attract females to the breeding areas and announce other males that a given territory is occupied. The aim of this study was to provide the detailed information on the breeding behaviour and the advertisement calls of Polypedates teraiensis. The morphometric measurements of the amplecting pairs (males and females) for sexual dimorphism along with clutch sizes were also studied.

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