Sexual dimorphism in a freshwater atyid shrimp (Decapoda: Caridea) with direct development: a geometric morphometrics approach

Zootaxa ◽  
2016 ◽  
Vol 4196 (1) ◽  
pp. 120 ◽  
Author(s):  
DANIELA ELIANA SGANGA ◽  
LUCAS RAUL FERNANDEZ PIANA ◽  
LAURA SUSANA LÓPEZ GRECO
Keyword(s):  
Sexual Dimorphism ◽  
Geometric Morphometrics ◽  
Mating System ◽  
Abdominal Segment ◽  
Sexual Size Dimorphism ◽  
Centroid Size ◽  
Caridean Shrimp ◽  
Size Dimorphism ◽  
Adult Females ◽  
Ornamental Species

Neocaridina davidi is a caridean shrimp that has gained popularity in recent years as an ornamental species. Using geometric morphometrics, we investigated sexual dimorphism in carapace and second abdominal segment shape of N. davidi. Adult females displayed a more elongated carapace and a longer rostrum than males. However, male carapace shape was similar to that of juvenile females. The second abdominal pleura was more elongated and wider in adult females than in males. Significant differences were found in centroid size for the carapace and the second abdominal segment between sexes, which is consistent with sexual size dimorphism. These results support the hypothesis of a “pure search” mating system in N. davidi, where small males search actively for receptive females, and after insemination they continue searching. 

Growth, maturity, and sexual dimorphism in the wood turtle, Clemmys insculpta

1990 ◽  
Vol 68 (4) ◽  
pp. 672-677 ◽  
Author(s):  
Jeffrey E. Lovich ◽  
Carl H. Ernst ◽  
John F. McBreen
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Carapace Length ◽  
Sexual Size Dimorphism ◽  
Von Bertalanffy ◽  
Size Dimorphism ◽  
Adult Females ◽  
Body Sizes ◽  
Von Bertalanffy Growth Model ◽  
Wood Turtle

Growth in the wood turtle (Clemmys insculpta) is described using the von Bertalanffy growth model and nonlinear regression. Growth in both sexes is similar until about 160 mm plastron length. Males grew at a faster rate after this size. Males appear to mature at a larger size and later age than females, although age-specific body size is highly variable. Sexual size dimorphism, in carapace length, is pronounced, with males attaining mean body sizes significantly larger (1.07–1.10 times) than those of adult females. Plastron length is an inappropriate measure of sexual size dimorphism because of the development of plastral concavity in males. Females tend to predominate in samples, possibly owing to differential maturity of the sexes. The direction of sexual size dimorphism may be maintained by intrasexual competition among males for access to females. Data for several adults captured at intervals of from 9 to 20 years support the concept of indeterminate growth.

scholarly journals Morphometric Analysis of the Host Effect on Phenotypical Variation ofBelminus ferroae(Hemiptera: Triatominae)

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Claudia Magaly Sandoval Ramirez ◽  
Elsa Evelia Nieves Blanco ◽  
Reinaldo Gutiérrez Marin ◽  
Diego Alexander Jaimes Mendez ◽  
Nelcy Ortiz Rodríguez ◽  
...  
Keyword(s):  
Morphometric Analysis ◽  
Sexual Size Dimorphism ◽  
Etiologic Agent ◽  
Wing Shape ◽  
Centroid Size ◽  
Mahalanobis Distances ◽  
Size Dimorphism ◽  
Host Effect ◽  
Successive Generations ◽  
Greater Wing

The Triatominae subfamily includes hematophagous insects, well known for their role as vectors for theTrypanosoma cruziparasite, etiologic agent of Chagas’ disease.Belminus ferroaeis a triatomine that showed an increased demographic fitness when cockroaches were used as hosts. Here we compare the centroid size (CS) and wing shape betweenB. ferroaeparents and three successive generations (O1, O2, and O3) of their offspring fed on cockroaches or mice under laboratory conditions. Morphometric analysis of the wings bugs fed on cockroaches showed a significant reduction in CS in both sexes among all generations. Sexual size dimorphism (SSD) was observed in the insects fed on cockroaches (O2 and O3), as well as those bugs fed on mice (O2). Differences in the shape of wings were observed between parental and offspring wings when fed on mice, but not in males (O1, O2, and O3) or females (O1 and O2) fed on cockroaches. There was a greater wing shape similarity between the cockroach-fed offspring and their parents according to the Mahalanobis distances. Our results support the idea of higher adaptation of this Triatominae with arthropod hosts.

scholarly journals A skeletochronological estimate of age and growth in a large riparian frog from Madagascar (Anura, Mantellidae, Mantidactylus)

Herpetozoa ◽  
2019 ◽  
Vol 32 ◽  
pp. 39-44 ◽  
Author(s):  
Fabio M. Guarino ◽  
Angelica Crottini ◽  
Marcello Mezzasalma ◽  
Jasmin E. Randrianirina ◽  
Franco Andreone
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Age And Growth ◽  
Growth Trajectories ◽  
Growth Coefficient ◽  
Size Dimorphism ◽  
Adult Females ◽  
Similar Growth

We characterized the body size (as snout-vent length), age, sexual size dimorphism, and growth rate in a population of one of the larger riparian frog from Madagascar (Mantidactylusgrandidieri) from a rainforest patch close to Vevembe, SE Madagascar. We identified a significant female-biased sexual size dimorphism. Age was estimated using phalangeal skeletochronology and was significantly higher in females than in males. Modal age class turned out to be 4 years in both sexes but a large percentage of adult females (75%) fell in the 5–6 years-old classes, while no male exceeded 4 years. We here report M.grandidieri as a medium-long-lived anuran species. Von Bertalanffy’s model showed similar growth trajectories between the sexes although the growth coefficient in females (k = 0.335) was slightly but not significantly higher than in males (k = 0.329).

Sexual size dimorphism in the viviparous caecilian amphibian Geotrypetes seraphini seraphini (Gymnophiona: Dermophiidae) including an updated overview of sexual dimorphism in caecilian amphibians

2016 ◽  
Vol 37 (3) ◽  
pp. 291-299 ◽  
Author(s):  
Markus Maerker ◽  
Sandy Reinhard ◽  
Peter Pogoda ◽  
Alexander Kupfer
Keyword(s):  
Sexual Dimorphism ◽  
Body Length ◽  
Sexual Size Dimorphism ◽  
Molecular Ecology ◽  
Female Size ◽  
Sexually Dimorphic ◽  
Size Dimorphism ◽  
Mating System Evolution ◽  
Accurate Comparison ◽  
Widespread Phenomenon

Sexual size dimorphism (SSD) describing intersexual size differences of a given taxon is a widespread phenomenon in the animal kingdom. SSD plays a significant role in understanding life history and mating system evolution. The snakelike morphology of limbless caecilian amphibians lacking obvious secondary sexual characters (in contrast to frogs and salamanders) impedes an accurate comparison between sexes.Here, the phylogenetically derived teresomatan and viviparous caecilianGeotrypetes seraphini seraphiniwas analysed for patterns of sexual dimorphism. In terms of body size females were the larger sex, but when body length was adjusted male-biased intersexual differences in cloacal shape appeared. The larger female size is likely explained by fecundity selection as clutch size was positively correlated to female body length. Unexpectedly a cryptic, ontogeny related variation of the nuchal collars was found. An overview of SSD in caecilians including data for 27 species of nine out of ten existing families revealed a quite high number of taxa showing sexually dimorphic head size dimensions exclusively present among phylogenetically derived teresomatan caecilians. Still further research including insights into the behavioural ecology and molecular ecology of mating systems is warranted to better understand the evolution of sexual size dimorphism of caecilian amphibians.

The evolution of sexual dimorphism in the lizard Anolis polylepis (Iguania): evidence from intraspecific variation in foraging behavior and diet

1996 ◽  
Vol 74 (7) ◽  
pp. 1238-1245 ◽  
Author(s):  
Gad Perry
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Feeding Behavior ◽  
Rain Forest ◽  
Sexual Size Dimorphism ◽  
Costa Rican ◽  
Agonistic Interactions ◽  
Size Dimorphism ◽  
Food Items ◽  
Competing Hypotheses

Two main explanations, intraspecific niche divergence and sexual selection, have been proposed to explain the origin of sexual size dimorphism. To test these competing hypotheses I studied the ecology, feeding behavior, and diet of the lizard Anolis polylepis in a Costa Rican rain forest. Male A. polylepis were significantly larger and heavier than females but ate smaller food items and had lower stomach volumes, despite possessing longer and wider heads. Males were more sedentary than females or juveniles, chose higher perches, and were more likely to be involved in agonistic interactions. Diets of males, females, and juveniles were also significantly different taxonomically. These data are consistent with the sexual selection origin theory but not with an ecological one. Thus, observed dietary differences probably evolved once dimorphism had been attained through sexual selection.

scholarly journals Sexual size dimorphism and sexual selection in artiodactyls

2020 ◽  
Vol 31 (3) ◽  
pp. 792-797
Author(s):  
Marcelo H Cassini
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Group Size ◽  
Sexual Size Dimorphism ◽  
Alternative Hypothesis ◽  
Mammalian Species ◽  
Generalized Least Squares ◽  
Size Dimorphism ◽  
Selection For

Abstract Sexual size dimorphism is biased toward males in most mammalian species. The most common explanation is precopulatory intramale sexual selection. Large males win fights and mate more frequently. In artiodactyls, previous tests of this hypothesis consisted of interspecific correlations of sexual dimorphism with group size as a surrogate for the intensity of sexual selection (Is). However, group size is not a proper measure of sexual selection for several reasons as is largely recognized in other mammalian taxa. I conducted an interspecific test on the role of sexual selection in the evolution of sexual dimorphism using the variance in genetic paternity as a proxy for the Is. I reviewed the literature and found 17 studies that allowed estimating Is= V/(W2), where V and W are the variance and mean number of offspring per male, respectively. A phylogenetic generalized least squares analysis indicated that dimorphism (Wm/Wf) showed a significant positive regression with the intensity of sexual selection but not group size (multiple r2= 0.40; F3,17= 12.78, P = 0.002). This result suggests that sexual selection may have played a role in the evolution of sexual size dimorphism in Artiodactyla. An alternative hypothesis based on natural selection is discussed.

scholarly journals Variation in Morphology and Mating System Among Island Populations of GaláPagos Hawks

The Condor ◽  
2003 ◽  
Vol 105 (3) ◽  
pp. 428-438 ◽  
Author(s):  
Jennifer L. Bollmer ◽  
Tania Sanchez ◽  
Michelle Donaghy Cannon ◽  
Didier Sanchez ◽  
Brian Cannon ◽  
...  
Keyword(s):  
Body Size ◽  
Mating System ◽  
Sexual Size Dimorphism ◽  
Negative Relationship ◽  
Interspecific Variation ◽  
Size Dimorphism ◽  
Island Populations ◽  
Cooperative Polyandry ◽  
El Sistema ◽  
Los Grupos

Abstract Interspecific variation in sexual size dimorphism has commonly been attributed to variation in social mating system, with dimorphism increasing as intrasexual competition for mates increases. In birds, overall body size has also been found to correlate positively with size dimorphism. In this study, we describe variation in morphology and mating system across six populations of the endemic Galápagos Hawk (Buteo galapagoensis). Galápagos Hawks exhibit cooperative polyandry, a mating system in which long-term social groups contain a single female and multiple males. Comparisons among islands revealed significant differences in overall body size for both adults and immatures. Populations ranged from completely monogamous to completely polyandrous, with varying mean group sizes. Data did not support our prediction that sexual size dimorphism would increase with the degree of polyandry (number of males per group) or with body size; there was no correlation between mating system and sexual dimorphism. We did find a significant negative relationship between degree of polyandry and body size among islands, opposite of the pattern predicted. Variación en Morfología y Sistema de Apareamiento entre Poblaciones de Buteo galapagoensis Resumen. Variación interespecífica en dimorfismo sexual ha sido atribuída comúnmente a variaciones del sistema social de apareamiento, de tal manera que el dimorfismo aumenta conforme aumenta la competencia intrasexual por parejas reproductivas. También se ha encontrado que el tamaño corporal se correlaciona positivamente con el dimorfismo. En este estudio describimos la variación morfológica y el grado de poliandría de seis poblaciones de Buteo galapagoensis, una especie que exhibe un sistema de apareamiento denominado poliandría cooperativa. En este sistema los grupos de individuos reproductivos incluyen una sola hembra y múltiples machos. Se comprobó que existen diferencias significativas en el tamaño del cuerpo de adultos y juveniles entre islas. Las poblaciones muestreadas variaron entre monógamas y completamente poliándricas, y el tamaño promedio de los grupos fue variable. Los datos no apoyaron las predicciones establecidas inicialmente pues el grado de dimorfismo sexual no aumentó con el nivel de poliandría (número de machos por grupo) ni con el tamaño corporal, ni hubo una correlación entre el sistema de apareamiento y el dimorfismo sexual. La relación entre el tamaño corporal y el sistema de apareamiento fue contraria a la que se predijo: hubo una correlación negativa significativa entre el grado de poliandría y el tamaño corporal entre islas.

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