Sexual dimorphism in the claws of the European terrapin (Emys orbicularis): potential implications for the reproductive fitness of the species.

2019 ◽  
Author(s):  
Gonzalo Alarcos ◽  
Jaime Madrigal-González ◽  
Miguel Lizana ◽  
Fabio Flechoso
Keyword(s):  
Sexual Selection ◽  
Comparative Analysis ◽  
Sexual Dimorphism ◽  
Reproductive Success ◽  
Sexual Maturity ◽  
Reproductive Fitness ◽  
Emys Orbicularis ◽  
Future Studies ◽  
Different Populations ◽  
Males And Females

There are many biometric differences between the males and females of the European pond turtle (Emys orbicularis) as regards their size, colouring, the shape of the plastron, tail, etc. The males use their claws to grasp the female during copulation and hence sexual selection should favour the males that have larger claws, which allow them to grasp the female better. Here, we address this type of sexual dimorphism in a comparative analysis of indices obtained from claw length, the length of the carapace and the locality where individuals were sampled. The results show that the curvature of the claws differs between the two sexes, being longer in males and increasing with age, size, and hence, the state of sexual maturity, than in females. Greater claw length could confer advantages for males when grasping the carapace of females, and hence, improve their reproductive fitness. Importance in the reproductive success that might have this feature in males could originate future studies that will relate the shape, thickness, length and other measures of the claws in males with their reproductive success in different populations, genetic variety, and most importantly, viability of populations. 

scholarly journals Safe sex: male–female coalitions and pre-copulatory mate-guarding in a fiddler crab

2009 ◽  
Vol 6 (2) ◽  
pp. 180-182 ◽  
Author(s):  
Richard N. C. Milner ◽  
Michael D. Jennions ◽  
Patricia R. Y. Backwell
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Success ◽  
Observational Data ◽  
Fiddler Crab ◽  
Lower Boundary ◽  
Mate Guarding ◽  
Maintenance Costs ◽  
Boundary Maintenance ◽  
Uca Annulipes ◽  
Males And Females

In fiddler crabs both males and females defend territories that are essential for survival. Given pronounced sexual dimorphism in weaponry, how do weaponless females defend their territory from well-armed males? Using observational data and two simple experiments, we test whether male Uca annulipes protect their female neighbours from conspecific intruders. We show that males defend their female neighbours against male but not female intruders. We also show that females sometimes mate with their immediate neighbours. Male defence of female neighbours appears to represent both pre-copulatory mate-guarding and a territorial coalition. Males who ensure that their neighbour remains female could benefit through increased opportunity for future reproductive success and lower boundary maintenance costs.

Long-term mating positively predicts both reproductive fitness and parental investment

2021 ◽  
pp. 1-12
Author(s):  
Janko Međedović
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Parental Investment ◽  
Reproductive Fitness ◽  
Human Populations ◽  
Number Of Children ◽  
Fitness Indicators ◽  
Number Of Sexual Partners ◽  
Sexual Selection Theory

Abstract Empirical data on the relations between mating and reproductive success are rare for humans, especially for industrial and post-industrial populations. Existing data show that mating (and especially long-term mating) can be beneficial for fitness, especially that of males. This finding is in line with the hypothesis of sexual selection operating in human populations. The present research expands on previous studies by: 1) analysing additional fitness indicators, including having children with different partners; 2) including parental investment in the analysis as another important marker of sexual selection; 3) analysing several mediators between mating, reproductive fitness and parental investment, i.e. age of first and last reproduction and desired number of children. The data were obtained in 2019 from a sample of parents living in Serbia (N=497). The findings showed that long-term mating (duration of longest partner relationship) was positively related to parental investment and number of offspring and grand-offspring. Furthermore, the link between long-term mating and reproductive success was completely mediated by the age of first reproduction and desired number of children. Short-term mating (number of sexual partners) was marginally positively related to the number of children participants had with different partners and negatively related to parental investment. No sex differences in the link between mating, fitness and parental investment were detected. In general, the signatures of sexual selection were weak in the present data, but those that were detected were in line with sexual selection theory. The present findings provide a deeper insight into the adaptive function of mating and also the mechanism of how mating is beneficial for fitness.

Differences in male and female cognitive abilities: Sexual selection or division of labor?

1996 ◽  
Vol 19 (2) ◽  
pp. 254-255
Author(s):  
Michael T. Ghiselin
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Sexual Dimorphism ◽  
Division Of Labor ◽  
Cognitive Abilities ◽  
Reproductive Competition ◽  
Male And Female ◽  
Males And Females

AbstractIn Darwinian terminology, “sexual selection” refers to purely reproductive competition and is conceptually distinct from natural selection as it affects reproduction generally. As natural selection may favor the evolution of sexual dimorphism by virtue of the division of labor between males and females, this possibility needs to be taken very seriously.

Reproduction of the water snake Helicops infrataeniatus (Colubridae) in southern Brazil

2005 ◽  
Vol 26 (4) ◽  
pp. 527-533 ◽  
Author(s):  
Luís Felipe Schmidt de Aguiar ◽  
Marcos Di-Bernardo
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Cycle ◽  
Sexual Maturity ◽  
Statistical Difference ◽  
Rio Grande ◽  
Southern Brazil ◽  
Rio Grande Do Sul ◽  
Water Snake ◽  
Males And Females ◽  
Two Peaks

AbstractThe reproductive cycle, sexual maturity, fecundity, and sexual dimorphism of Helicops infrataeniatus Jan, 1865, were inferred from the analysis of 374 preserved specimens (110 males, 140 females) from the eastern Central Depression of Rio Grande do Sul, Brazil. There was no statistical difference between the SVL of newborn males and females, but mature females attained greater length than mature males. The tail of mature individuals was proportionally longer in males than in females. Males matured at a smaller size than females. The reproductive cycle of this species was longer than what is known for oviparous colubrids from subtropical and temperate zones of Brazil. In the studied population, vitellogenesis occurred from September to February. Oviductal embryos were found from September to May. Births took place in September, January, February and March, and occurred in two peaks. Litter size ranged from 5 to 22 offspring. The differences between the number of vitellogenic follicles and embryos, and between embryos and newborns were not significant, thus practically all follicles were generally converted into embryos and embryos into newborns.

Sexual conflict inGerris gillettei(Insecta: Hemiptera): influence of effective mating rate and morphology on reproductive success

2012 ◽  
Vol 90 (11) ◽  
pp. 1297-1306 ◽  
Author(s):  
Marie-Claude Gagnon ◽  
Pierre Duchesne ◽  
Julie Turgeon
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Sexual Conflict ◽  
Water Strider ◽  
Mating Rate ◽  
Multiple Matings ◽  
Males And Females ◽  
Genetic Mating System ◽  
Selection Framework ◽  
Resistance Traits

In water striders, the interests of both sexes diverge over the decision to mate, leading to precopulatory sexual conflict. The influence of mating rate and key persistence and resistance traits on reproductive success has seldom been investigated in the context of multiple matings. We used amplified fragment length polymorphism (AFLP) based genetic parentage analyses to estimate mating and reproductive success in Gerris gillettei Lethierry and Severin, 1896, while allowing for free multiple matings. We tested the hypotheses that males should display stronger opportunity for sexual selection and steeper Bateman gradients. In each sex, persistence and resistance traits should also impact mating and reproductive success. Surprisingly, males and females had similarly high and variable effective mating rates (i.e., number of genetic partners), and both sexes produce more offspring when mating with more partners. As predicted, exaggerated persistence traits allowed males to mate with more partners and sire more offspring. However, we found no evidence for an impact of resistance traits for females. The mating environment may have favoured low resistance in females, but high promiscuity can be beneficial for females. This first description of the genetic mating system for a water strider species suggests that the determinants of fitness can be further deciphered using the sexual selection framework.

scholarly journals Relative growth of freshwater prawn Macrobrachium brasiliense (Decapoda, Palaemonidae) and its implications for reproduction

2019 ◽  
Vol 109 ◽  
Author(s):  
Caio dos Santos Nogueira ◽  
Marcela Silvano de Oliveira ◽  
Giuliano Buzá Jacobucci ◽  
Ariádine Cristine de Almeida
Keyword(s):  
Sexual Dimorphism ◽  
Sexual Maturity ◽  
Carapace Length ◽  
Freshwater Prawn ◽  
Relative Growth ◽  
Guarding Behavior ◽  
Males And Females ◽  
One Year ◽  
Almost All

ABSTRACT The main objective of this study was to estimate the morphological sexual maturity of Macrobrachium brasiliense (Heller, 1862) and to analyze the relative growth of the species. During one year of sampling, from July 2012 to June 2013, 199 specimens were collected in a stream located in a Cerrado biome, in the Triângulo Mineiro region, state of Minas Gerais. Once identified and sexed, the length of the carapace, the length of the segments of the chelipeds (ischium, merus, carpus, propodus and dactyl) and width of the pleura were measured (mm). The maximum and mean sizes of the carapace length measured 20.5 mm (Mean: 9.6 ± 4.2 mm) and 20.1 mm (Mean: 7.7 ± 3.4 mm) for males and females, respectively. The propodus length for males, and the pleura width for females, were used for the classification of the specimens into juvenile and adult, using K-means analysis and discriminant analysis. The relative growth of the species was also evaluated through covariance analysis for all structures (ANCOVA, α = 0.05). In females, the growth of most structures occurred equally between juveniles and adults, with the exception of the merus and pleura structures. On the other hand, the growth of almost all structures of males differed between juveniles and adults. Only the carpus and the pleura growth were similar. We also estimated the size at onset of morphological sexual maturity at 8.64 mm CL for males (CL50% r = 1.71) and 8.03 mm CL for females (CL50% r = 0.07). Our results contribute to the understanding of some important questions related to the reproductive biology of M. brasiliense. We noted that males grow differently from females and become the largest individuals in the population, resulting in a sexual dimorphism. Such sexual dimorphism might promote the development of the temporary mating guarding behavior, a reproductive strategy very important for caridean shrimps.

scholarly journals Ontogenetic allometry in the foot size of Oligoryzomys flavescens (Waterhouse, 1837) (Rodentia, Sigmodontinae)

2015 ◽  
Vol 75 (2) ◽  
pp. 435-441 ◽  
Author(s):  
R. Maestri ◽  
R. Fornel ◽  
TRO. Freitas ◽  
JR. Marinho
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Sexual Dimorphism ◽  
Encounter Rate ◽  
Allometric Growth ◽  
Positive Allometry ◽  
Rate Of Growth ◽  
Ontogenetic Allometry ◽  
Males And Females ◽  
Oligoryzomys Flavescens

Ontogenetic allometry is the study of how the size or shape of certain structures changes over the course of an animal’s development. In this study, using Huxley's formula of allometric growth (1932), we assessed the changes in the rate of growth of the feet size of the sigmodontine rodent Oligoryzomys flavescens during its ontogeny and compared differences between males and females. We find evidence of a change of polarity during the ontogenetic development of the species, with the presence of positive allometry during pregnancy and negative allometry in adulthood. Moreover, we note the presence of sexual dimorphism in the size of the feet, in which males of the species have a higher rate of growth than females. This growth pattern is positively related to escape from predators in childhood in both sexes and, in adulthood, provides a higher encounter rate of females by males, due to the larger displacement of the latter. We suggest that both the forces of natural selection and sexual selection have acted to shape the evolution of foot size in this species.

Sexual Selection in Dung Beetles .1. A Multivariate Study of the Morphological Variation in 2 Species of Onthophagus (Scarabaeidae, Onthophagini)

1987 ◽  
Vol 35 (2) ◽  
pp. 123 ◽  
Author(s):  
D Cook
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Morphometric Analysis ◽  
Body Shape ◽  
Dung Beetles ◽  
Structural Polymorphism ◽  
Multivariate Study ◽  
History Of ◽  
Males And Females ◽  
Horned Beetles

Sexual dimorphism in horned beetles reflects a history of different selection pressures operating on males and females. A multivariate morphometric analysis was carried out on two scarabaeine dung beetles, Onthophagus binodis Thunberg and O. ferox Harold. There is clear structural polymorphism within O. binodis; horned males, females and hornless males were separated on the basis of body shape. Sexual dimorphism within O. ferox was established; sexes were separated according to the size of pronotal and cephalic horns. The effect of differential selection is discussed within the context of sexual selection.

scholarly journals Morphometric measurements of the European pond turtle (Emys orbicularis)(L., 1758) in Lithuania

Biologija ◽  
2021 ◽  
Vol 67 (2) ◽  
Author(s):  
Karolina Lukošiūtė ◽  
Monika Brimaitė ◽  
Alma Pikūnienė ◽  
Ramūnas Krugelis ◽  
Algimantas Paulauskas
Keyword(s):  
Sexual Dimorphism ◽  
Protected Areas ◽  
Shell Height ◽  
Size Variation ◽  
Ecological Network ◽  
Morphometric Measurements ◽  
Emys Orbicularis ◽  
Life Project ◽  
Pond Turtle ◽  
Males And Females

In Lithuania, the number of European pond turtles Emys orbicularis decreased between 1975 and 2010, but increased significantly between 2010 and 2014, when the LIFE project was implemented. During this project, an ecological network was created, habitats were restored in protected areas, and European pond turtle nesting areas were protected from predators. Very few morphometric measurements of European pond turtles are carried out in Lithuania. The purpose of this study was to perform morphometric measurements, assess migration, spread, and morphometric size variation. Morphometric measurements of juvenile European pond turtles showed that the morphometric indicators depended on the place of habitation: males from Juodabalė Zoological Reserve (Meteliai Regional Park) are smaller than females. Also, female turtles from Meteliai Regional Park are larger than both males and females from Kučiuliškė Herpetological Reserve. When comparing the morphometric indicators of males and females at ten months of age, sexual dimorphism is already observed: the shell height, the width of the head, carapace, and plastron of a females are already bigger than those of males.

scholarly journals Size at morphological maturity of Ucides cordatus (Linnaeus, 1763) (Brachyura, Ocypodidae) in the Laranjeiras Bay, Southern Brazil

2005 ◽  
Vol 48 (1) ◽  
pp. 139-145 ◽  
Author(s):  
Glaucia Dalabona ◽  
Jayme de Loyola e Silva ◽  
Marcelo Antonio Amaro Pinheiro
Keyword(s):  
Sexual Dimorphism ◽  
Sexual Maturity ◽  
Carapace Length ◽  
Carapace Width ◽  
Southern Brazil ◽  
Monthly Basis ◽  
Ucides Cordatus ◽  
Size At Sexual Maturity ◽  
Males And Females ◽  
One Year

Morphometry and maturity of Ucides cordatus were analyzed with males and females collected during one year on a monthly basis at Laranjeiras Bay, Paraná State, Brazil. Carapace length, chelipeds propodus length and abdominal width were measured and related to carapace width to verify sexual dimorphism and size at morphological maturity of each sex. Carapace and propodus length of larger and smaller cheliped presented difference between sexes, confirming the use of both as secondary sexual characters. MATURE II program indicated 44mm and 43mm of carapace width to represent the size at sexual maturity of males and females, respectively.

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