scholarly journals Rheotaxis Response Based on Sexual Dimorphism in the Green Swordtail Fish, Xiphophorus hellerii

Biota ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 128-139
Author(s):  
Muhammad Irsyad Abiyusfi Ghafari ◽  
Vita Fitrianti
Keyword(s):  
Sexual Dimorphism ◽  
Gravid Female ◽  
Adult Males ◽  
Dioecious Species ◽  
Swordtail Fish ◽  
Xiphophorus Hellerii ◽  
Males And Females ◽  
Morphological Differences ◽  
Gravid Females ◽  
The Individual

Morphological distinctions between males and females of a species are referred to by sexual dimorphism. It may result from various selection pressures affecting either sex or both and may occur in any dioecious species, including Green Swordtail fish, which are sexually reproductive. This study examined the different rheotaxis responses of Xiphophorus hellerii based on different sexes and morphological features. We analyzed ten adult males, ten gravid females, and ten non-gravid females of Xiphophorus helleri collected down the river and transferred into the column. We counted the number of the individual that performed positive rheotaxis (+), negative rheotaxis (-), and indifference response (0). The result showed different rheotaxis responses shown by male, non-gravid female, and gravid female X. hellerii. The highest percentage of positive rheotaxis response (movement against the current) was shown by non-gravid female X. hellerii, reaching up to 89%. Morphological differences between male, non-gravid female, and gravid female X. hellerii appear to affect the orientation and ability of X. hellerii in giving response against current and certainly has an impact on their survival in nature.

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 Sexual dimorphism in the electric knifefish, Gymnorhamphichthys rondoni (Rhamphichthyidae: Gymnotiformes)

2019 ◽  
Vol 49 (3) ◽  
pp. 213-220
Author(s):  
Elisa Queiroz GARCIA ◽  
Jansen ZUANON
Keyword(s):  
Sexual Dimorphism ◽  
Body Height ◽  
Principal Component ◽  
The Body ◽  
Vertical Line ◽  
Head Length ◽  
Genital Papilla ◽  
Adult Males ◽  
Dioecious Species ◽  
Males And Females

ABSTRACT Sexual dimorfism refers to morphological differences between males and females of a species. It may be a result of different selection pressures acting on either or both sexes and may occur in any sexually-reproducing dioecious species, including fishes. We analyzed 63 females and 63 adult males of Gymnorhamphichthys rondoni (Gymnotiformes) collected by us or deposited in museum collections. Sex was identified through abdominal dissection. We measured length from snout to posterior end of anal-fin, anal-fin length, distance from anus to anal-fin origin, distance from genital papilla to anal-fin origin, body width at beginning of anal-fin, and head length. Morphometric data submitted to a Principal Component Analysis (PCA) grouped males and females according to variables related to body size (along the first component) and to head length and body height along the second and third components. Females were larger than males, whereas males had proportionally larger heads and higher bodies than females. The urogenital papilla of males and females showed differences in shape, size and relative position on the body. The female papilla was elongated horizontally, larger than that of males, and was located on a vertical line below the eye, while the papilla of the males was vertically elongated and located on a vertical line below the operculum. To our knowledge, this is the first recorded case of sexual dimorphism in a species of Rhamphichthyidae, a condition that is now known in all the currently recognized families of Gymnotiformes.

scholarly journals New Macrostylidae Hansen, 1916 (Crustacea: Isopoda) from the Gay Head-Bermuda transect with special consideration of sexual dimorphism

Zootaxa ◽  
2012 ◽  
Vol 3277 (1) ◽  
pp. 1 ◽  
Author(s):  
TORBEN RIEHL ◽  
GEORGE D. F. WILSON ◽  
ROBERT R. HESSLER
Keyword(s):  
Sexual Dimorphism ◽  
Special Consideration ◽  
Adult Males ◽  
Remarkable Similarity ◽  
The Family ◽  
Morphological Differences

In the Asellota, sexual dimorphism is often characterized by males that show pronounced morphological differences after thefinal moult compared to females but also to sub-adult males. Such a sexual dimorphism may strongly complicate allocation ofthese terminal males to conspecifics. Consequently, we regard it to be a likely explanation for why in 50% of the described spe-cies of the family Macrostylidae Hansen, 1916, only one sex is known. Based on detailed description of two previouslyunknown species of the isopod genus Macrostylis Sars, 1864, the changes in the morphology that can occur during the finalmoult of the males are highlighted. M. dorsaetosa n. sp. is unlike any other species owing to the row of spine-like setae on theposterior margins of pereonites 5–6. M. strigosa Mezhov, 1999 shows remarkable similarity but lacks these setae. In M. papil-lata n. sp., cuticular ridges overlap posteriorly with the margin of the pereonites 1–4 and head forming a warty appearance. Thisspecies is easily identifiable and unlike any previously described macrostylid owing to the presence of the tergal articulationbetween pleonite 1 and pleotelson. Information for the identification of terminal males is provided and implications of our results for future taxonomic and systematic work on this isopod family are discussed.

scholarly journals The Diet and Sexual Differences of the Caspian Bent-Toed Gecko,Tenuidactylus caspius(Squamata: Gekkonidae), in Northern Iran

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Vida Hojati ◽  
Reza Babaei Savasari
Keyword(s):  
Sexual Dimorphism ◽  
Culex Pipiens ◽  
Tail Length ◽  
Adult Males ◽  
Northern Iran ◽  
Widespread Distribution ◽  
Adult Females ◽  
Significant Difference ◽  
Males And Females ◽  
Prey Items

The Caspian bent-toed gecko,Tenuidactylus caspius, is one of the most common nocturnal lizards of Iran with widespread distribution especially in the northern provinces. This research was done in order to study the diet and sexual dimorphism of this species in Sari County from 5 May to 20 October. During this research, 40 specimens of them including 20 males and 20 females were studied for diet and 140 specimens including 70 adult males and 70 adult females were studied for sexual dimorphism. Prey items identified were insects that belong to 15 species of 8 families and 6 orders. The most common prey items wereCulex pipiensandMusca domestica. There is no significant difference between diets of males and females. Results show that the adult males in addition of having the apparent femoral and preanal pores are heavier than females and have larger body, head, and tail length.

Sexual dimorphism in the carapace shape and length of the freshwater palaemonid shrimp Macrobrachium potiuna (Müller, 1880) (Decapoda: Caridea: Palaemonidae): geometric and traditional morphometric approaches

2017 ◽  
Vol 67 (2) ◽  
pp. 93-103 ◽  
Author(s):  
Madson Silveira de Melo ◽  
Setuko Masunari
Keyword(s):  
Body Weight ◽  
Sexual Dimorphism ◽  
Behavioral Differences ◽  
Geometric Morphometric ◽  
Freshwater Shrimps ◽  
Morphometric Analyses ◽  
Males And Females ◽  
Morphological Differences ◽  
Three Rivers ◽  
Coastal Basin

Sexual dimorphism is characterized by morphological, physiological, or behavioral differences between males and females. The genus Macrobrachium is a diverse group of freshwater shrimps distributed throughout tropical and subtropical regions. They have a great intra- and interspecific morphological variation, with some species showing sexual dimorphism. We investigated the sexual dimorphism of the size and shape of the carapace and body weight of Macrobrachium potiuna (Müller, 1880) in three populations of the State of Paraná through traditional and geometric morphometric techniques. The populations were sampled from three rivers: the Pombas River, Coastal Basin, the Piraquara River, First Plateau, and the Guabiroba River, Second Plateau. Morphometric analyses indicated that male shrimps showed differences in carapace length and body weight: the higher the distance from the sea, the smaller and lighter the shrimps. Carapace shape also differed significantly between the sexes in all three populations, with males having a less robust carapace, but a more elongated rostrum than females. The morphological differences between the genders seem to reflect the reproductive roles of males and females in this environment.

scholarly journals Hydraulic constraints of reproduction do not explain sexual dimorphism in the genus Leucadendron (Proteaceae)

2017 ◽  
Author(s):  
Adam B. Roddy ◽  
Justin van Blerk ◽  
Jeremy J. Midgley ◽  
Adam G. West
Keyword(s):  
Sexual Dimorphism ◽  
Fire Frequency ◽  
Sexually Dimorphic ◽  
Hydraulic Efficiency ◽  
Costs Of Reproduction ◽  
Dioecious Species ◽  
Shoot Architecture ◽  
Males And Females ◽  
And Function ◽  
In Fire

AbstractBecause of the importance of reproduction in plant life history, the physiological costs of reproduction often influence vegetative structure and function. In dioecious species, these effects can be quite obvious, as different costs of male and female reproductive functions are entirely separated among different individuals in a population. In fire-prone ecosystems, in which recruitment is driven by fire frequency, many plants will maintain their seeds in the canopy, only to be released after a fire. The dioecious genus Leucadendron is a notable case of this, as females can maintain their seed cones for years, and, even more interestingly, species in the genus differ substantially in the degree to which males and females are sexually dimorphic. A recent study (Harris and Pannell 2010) argued that the hydraulic costs of maintaining seed cones for many years would effect the degree of sexual dimorphism among species. However, this assumed that shoot hydraulic architecture would be related to traits exhibiting sexual dimorphism. Here we explicitly test this hypothesis on two Leucadendron species. We found (1) that metrics of branch ramification used in the previous study to characterize dimorphism do not conform to known scaling relationships and (2) that sexual dimorphism in shoot architecture has no effect on hydraulic efficiency. Both of these results seriously question the pattern described by Harris and Pannell (2010) and suggest that the hydraulic costs of prolonged seed retention in Leucadendron do not significantly affect branch architecture.

scholarly journals The Roles of DNA Methyltransferases 1 (DNMT1) in Regulating Sexual Dimorphism in the Cotton Mealybug, Phenacoccus solenopsis

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 121 ◽  
Author(s):  
Mohamed A.A. Omar ◽  
Meizhen Li ◽  
Feiling Liu ◽  
Kang He ◽  
Muhammad Qasim ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Dna Methyltransferase ◽  
Dna Methyltransferases ◽  
Invasive Pest ◽  
Adult Males ◽  
Small Interfering Rnas ◽  
Phenacoccus Solenopsis ◽  
Adult Females ◽  
Cotton Mealybug ◽  
Gravid Females

The cotton mealybug, Phenacoccus solenopsis, is an invasive pest that can cause massive damage to many host plants of agricultural importance. P. solenopsis is highly polyphagous, and shows extreme sexual dimorphism between males and females. The functions of DNA methyltransferase (DNMT) enzymes in the cotton mealybug have not been well studied. Here, we carried out an investigation of DNMTs in cotton mealybug to study their roles in sexual dimorphism. We found that the cotton mealybug has two copies of PsDnmt1, but Dnmt3 is absent. We then amplified the full-length cDNAs of PsDnmt1A (2225 bp) and PsDnmt1B (2862 bp) using rapid amplification cDNA ends (RACE). Quantitative reverse transcriptase PCR shows that both PsDnmt1A and PsDnmt1B are highly expressed in adult males, while the expression of PsDnmt1B is 30-fold higher in gravid females than in virgin females. We knocked down PsDnmt1A and PsDnmt1B with small interfering RNAs (siRNAs), and both genes were successfully down-regulated after 24 h or 72 h in adult females and pupa (t-test, p < 0.05). Down-regulating the expression of these two DNMT genes led to offspring lethality and abnormal body color in adult females. Furthermore, the silencing of PsDnmt1B induced abnormal wing development in emerged adult males. Our results provide evidence that PsDnmt1 plays a crucial role in regulating sexual dimorphism in the cotton mealybug.

Sexual dimorphism in the biomechanical and toxicological performance in prey incapacitation of two morphologically distinct scorpion species (Chactas sp. and Centruroides sp.)

2019 ◽  
Author(s):  
Julio César González-Gómez ◽  
Juan Carlos Valenzuela-Rojas ◽  
Luis Fernando García ◽  
Lida Marcela Franco Pérez ◽  
Giovany Guevara ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Niche Partitioning ◽  
Pinch Force ◽  
Ecological Implications ◽  
Males And Females ◽  
Morphological Differences ◽  
Force Volume

Abstract Morphological differences between the sexes are a common feature in many groups of animals and can have important ecological implications for courtship, mating, access to prey and, in some cases, intersex niche partitioning. In this study, we evaluated the role of sexual dimorphism in the performance of the two structures that mediate the ability to access prey, the pinchers or chelae and the venomous stinger, in two species of scorpions with contrasting morphologies: Chactas sp., which has marked sexual dimorphism in the chelae, and Centruroides sp., which does not have such marked dimorphism in the chelae. We evaluated aspects such as chela pinch force, toxicity to prey (LD50) and the volume of venom in males and females of each species. We found significant differences between males and females of Chactas sp. in the chela pinch force, volume of venom and LD50. In contrast, for Centruroides sp., no differences between males and females were found in any of these traits. We discuss several potential selective regimes that could account for the pattern observed.

Sexual dimorphism in the baiji, Lipotes vexillifer

1992 ◽  
Vol 70 (8) ◽  
pp. 1484-1493 ◽  
Author(s):  
Gao Anli ◽  
Zhou Kaiya
Keyword(s):  
Sexual Dimorphism ◽  
Body Length ◽  
Young Female ◽  
The Body ◽  
Analysis Of Covariance ◽  
Adult Males ◽  
Genital Aperture ◽  
Condylobasal Length ◽  
Males And Females ◽  
Width Measurements

Dimorphism was detected in body length and in skull dimensions of the baiji, Lipotes vexillifer. The age of a sample comprising 22 females and 14 males was estimated. A single-phase Laird growth model was fitted to the body length versus age data for females. Two curves were required for the males, one for those with 4 dentinal growth layer groups (GLGs) and another for those above that age, i.e., with more than 4 GLGs. Males and females have about the same growth rate until they have about 4 GLGs, after which males grow more slowly than females. Sexual dimorphism was also found in 9 external measurements, based on t-tests. Analysis of covariance showed that once the effect of body length was removed, only 1 of the 9 measurements, from the tip of the upper jaw to the genital aperture, differed significantly between males and females. Differences in skull measurements resulted mainly from an early slowdown in the rate of longitudinal growth of the male, before the increase in body length slowed. Females and males could be correctly sexed by discriminant analysis using the body length, condylobasal length, and zygomatic width, and also the condylobasal length, width of the rostrum at the base, and the zygomatic width, except for one young female. Eight skull length measurements were greater in adult females than in adult males after the effect of body length was removed, and five skull width measurements were greater in males when the effect of condylobasal length was removed. Asymmetry in the position of the blowhole and in skew of the skull is pronounced and is independent of body length and sex.

Distribution and reproductive biology of the blackchin guitarfish, Rhinobatos cemiculus (Pisces: Rhinobatidae), in Tunisian waters (central Mediterranean)

1994 ◽  
Vol 45 (4) ◽  
pp. 551 ◽  
Author(s):  
C Capape ◽  
J Zaouali
Keyword(s):  
Reproductive Biology ◽  
Gravid Female ◽  
Total Sample ◽  
High Rate ◽  
Adult Males ◽  
Central Mediterranean ◽  
Chemical Balance ◽  
Adult Females ◽  
Males And Females ◽  
The Mean

Aspects of the reproductive biology of Rhinobatos cemiculus are described from specimens collected in Tunisian waters. Sizes at first sexual maturity of males and females are 1000 mm and 1100 mm total length (TL), respectively. Adult females are generally larger than adult males, the maximum TL for males and females being 1920 mm and 2300 mm, respectively. The smallest gravid female observed was 1220 mm TL. R. cemiculus is an aplacental viviparous species, with each female having two ovaries and two uteri, both functional. Ripe oocytes in the ovaries, ova, embryos and fully developed fetuses in the uteri are symmetrically distributed. The gestation period could last for a maximum of eight months. Vitellogenesis proceeds in parallel with gestation, and at the time of parturition a crop of ripe oocytes is ready to be ovulated. Ovulation and parturition occur during winter and summer, respectively. There is probably one litter per year. The mean TL and mean weight of fully developed fetuses are 39.6 mm and 115.1 g, respectively. A computed chemical balance of development, based on the mean dry weights of fully developed fetuses and ripe oocytes, is 1.01. This low value is due to the fact that R. cemiculus is purely a lecithotrophic species. Fecundity ranges from 5 to 12 young per litter. Ovarian fecundity and uterine fecundity are slightly correlated with the size of females. Females are more numerous than males in the total sample, as well as in utero and at the juvenile stage; however, this is not the case for subadults and adults. This phenomenon is probably due to segregation of the sexes at different depths during certain stages of the reproductive cycle rather than to a high rate of mortality among subadult and adult females.

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