scholarly journals Parasitic manipulation or by-product of infection: an experimental approach using trematode-infected snails

2022 ◽  
Vol 96 ◽  
Author(s):  
Alice Namias ◽  
Lynda F. Delph ◽  
Curtis M. Lively
Keyword(s):  
Natural Selection ◽  
Sexual Dimorphism ◽  
Experimental Approach ◽  
Normal Development ◽  
Parasite Fitness ◽  
Size And Shape ◽  
Host Growth ◽  
Internal Volume ◽  
One Year ◽  
Outdoor Mesocosms

Abstract Natural selection should favour parasite genotypes that manipulate hosts in ways that enhance parasite fitness. However, it is also possible that the effects of infection are not adaptive. Here we experimentally examined the phenotypic effects of infection in a snail–trematode system. These trematodes (Atriophallophorus winterbourni) produce larval cysts within the snail's shell (Potamopyrgus antipodarum); hence the internal shell volume determines the total number of parasite cysts produced. Infected snails in the field tend to be larger than uninfected snails, suggesting the hypothesis that parasites manipulate host growth so as to increase the space available for trematode reproduction. To test the hypothesis, we exposed juvenile snails to trematode eggs. Snails were then left to grow for about one year in 800-l outdoor mesocosms. We found that uninfected males were smaller than uninfected females (sexual dimorphism). We also found that infection did not affect the shell dimensions of males. However, infected females were smaller than uninfected females. Hence, infection stunts the growth of females, and (contrary to the hypothesis) it results in a smaller internal volume for larval cysts. Finally, infected females resembled males in size and shape, suggesting the possibility that parasitic castration prevents the normal development of females. These results thus indicate that the parasite is not manipulating the growth of infected hosts so as to increase the number of larval cysts, although alternative adaptive explanations are possible.

Sexual dimorphism, deformations, and epibionts of Phrynops tuberosus (Testudines, Chelidae)

2015 ◽  
Vol 65 (3-4) ◽  
pp. 311-320 ◽  
Author(s):  
João Fabrício Mota Rodrigues ◽  
José Roberto Feitosa Silva
Keyword(s):  
Sexual Dimorphism ◽  
Natural History ◽  
Tail Length ◽  
Condition Index ◽  
Head Width ◽  
Body Condition Index ◽  
Future Studies ◽  
History Of ◽  
One Year ◽  
Effective Conservation

Studies focusing on the natural history of species are essential for developing effective conservation measures and evaluating ecological hypotheses. To this end, we describe natural history data of the Cotinga River toadhead turtle, Phrynops tuberosus, in the Banabuiú River in Ceará, Brazil, and evaluated sexual dimorphism, epibionts, and mutilation effects. We hand-captured 134 individuals by snorkeling, over a period of one year, resulting in the capture of 94 males, 24 females, and 16 juveniles. Females had larger head width and body mass than males, while males had longer tail length. One quarter of the turtles captured had some sort of injury or deformation, most common injuries being missing claws, mutilations, and shell deformations. We found no difference in body condition index between mutilated and non-mutilated animals. Mollusks, insects, and leeches were found as epibionts on P. tuberosus and most of the captured turtles had extensive algal cover. Future studies should focus on understanding the effect of mutilations on animal fitness and reproductive success.

Phenotypical characterization of Kababich breed in peri-urban zone of N’Djamena-Chad

2021 ◽  
Vol 2 (2) ◽  
pp. 041-049
Author(s):  
Djalal Ardjoun Khalil ◽  
Mahamat Ibrahim Souleymane ◽  
Issa Youssouf ◽  
Madjina Tellah ◽  
Mopate Logtene Youssouf ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Genetic Improvement ◽  
The Body ◽  
Phenotypic Characterization ◽  
Phenotypic Traits ◽  
Phenotypic Characteristics ◽  
Young Males ◽  
Urban Zone ◽  
One Year

This work was carried out on the phenotypic characteristics of the Kababich sheep exploited in the peri-urban zone of N'Djamena (Chad). This phenotypic characterization of Kababich sheep should be continued on local breeds for genetic improvement and objective optimization of productivity. The objective of this study is the characterization of phenotypically Kababich sheep exploited in the peri-urban area of ​​N'Djamena-Chad. It was conducted in 39 farms and involved 1035 sheep aged less than one year old. Phenotypic traits were measured according to the guideline defined by FAO. A total of 12 variables were measured including five qualitative and seven quantitative. The results obtained show a positively significant correlation (p> 0.001) between the age of the sheep estimated by the breeder and the dentition (0.83). The ears are drooping and measure 17.90 ± 2.77 cm. The color of the brown dress (fawn) and the smooth and short coat are dominant. The females are matte and the rams of brown dress have horns in the forms of the vestiges. The Kababich is large with a height at the withers of 81.50 ± 9.40 cm, a rump height of 83.24 ± 9.42 cm and a chest circumference of 88.29 ± 9.22 cm. The body is 72.82 ± 9.63 cm long, has a basin width of 19.89 ± 2.53 cm and a chest depth of 40.68 ± 5.16 cm. These measurements show that Kababich is a meat breed by excellence. In addition, the sexual dimorphism very accentuated in this race orients towards a valorization of the young males in the fattening workshops.

scholarly journals Sexual dimorphism in the size and shape of the raptorial pedipalps of Giant Whip Spiders (Arachnida: Amblypygi)

2019 ◽  
Vol 310 (1) ◽  
pp. 45-54
Author(s):  
C.J. McLean ◽  
R.J. Garwood ◽  
C.A. Brassey
Keyword(s):  
Sexual Dimorphism ◽  
Size And Shape

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.

A new fouling Hydroides (Annelida, Sabellida, Serpulidae) from southern Gulf of California

2015 ◽  
pp. 1-13 ◽  
Author(s):  
María Ana Tovar-Hernández ◽  
Tulio F. Villalobos-Guerrero ◽  
Elena K. Kupriyanova ◽  
Yanan Sun
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Sexual Dimorphism ◽  
Gulf Of California ◽  
Sequence Data ◽  
Marine Fouling ◽  
Size And Shape ◽  
Broadcast Spawner ◽  
Polychaete Family ◽  
A New Species

Members of the tubicolous polychaete family Serpulidae constitute one of the most important groups of marine fouling biota. This paper describes a new species of the serpulid genusHydroidesfrom dock fouling at Mazatlán (southern Gulf of California), providing information about live colouration and reproductive features.Hydroides dolabrussp. nov. belongs to a subgroup of species in which verticil spines are equal in size and shape, lack both external and lateral spinules, but have various modifications to their tips. However,Hydroides dolabrussp. nov. is distinct in having tips of verticil spines pickaxe-shaped, with asymmetrical triangular radially orientated projections: the internal projections are short and point inward the verticil centre, while longer external projections point outward the verticil centre. Like all species of the genus,H. dolabrussp. nov. is a gonochoristic broadcast spawner lacking sexual dimorphism. A phylogenetic analysis of Hydroides based on COI, 18S and cytbsequence data reveals thatH. dolabrussp. nov. is genetically distinct from other species ofHydroidesfor which sequence data are available. The new species is the 11th in the genus described from Mexican waters.

scholarly journals Nasal index among Students of People’s Dental College and Hospital

2019 ◽  
Vol 1 (1) ◽  
pp. 21-27
Author(s):  
Mangesh Bajracharya ◽  
Samjhana Sharma
Keyword(s):  
Ethnic Identity ◽  
Sexual Dimorphism ◽  
Female Students ◽  
Baseline Data ◽  
Craniofacial Surgery ◽  
Male And Female ◽  
Size And Shape ◽  
Gender Differentiation ◽  
Significant Difference ◽  
The Mean

Introduction: Nasal anthropometry is a study that deals with the measurements of the proportion, size, and shape of the nose. The nasal index is considered as one of the major landmarks for craniofacial surgery, gender differentiation, and ethnic identity. This study is aimed to provide baseline data of the nasal index of Nepalese people and to assess the gender variation which will be of clinical, surgical interest in rhinology and craniofacial prosthetic purpose. Methods: BDS students from 17 to 25 years with various ethnicity were included in the study. A total of 160 students with an equal number of male and female students was included. Nasal parameters were measured and the nasal index was calculated for each student. Result: The mean nasal index was 78.03±7.07 suggesting Mesorrhine type of nose. The nasal width and height show statistically significant differences whereas there was no significant difference found between the nasal indices of male and female students. Hill Janajati showed the highest nasal index followed by Newar, Brahmin and Chettri; and Others. Conclusion: The study concludes the type of nose has an effect on gender when compared between the sex but the nasal index calculated to have a little contribution to sexual dimorphism. Mesorrhine nose was found to be most frequent. Among the population, Hill Janajati showed the highest nasal index. We recommend further study to compare the nasal index of various ethnical groups of the Nepalese population. Keywords: Anthropometry, Mesorrhine, Nasal Index

scholarly journals Morphometric differentiation and sexual dimorphism in Limnomedusa macroglossa (Duméril & Bibron, 1841) (Anura: Alsodidae) from Uruguay

2021 ◽  
Vol 16 (1) ◽  
pp. 11-25
Author(s):  
Valeria De Olivera-López ◽  
Arley Camargo ◽  
Raúl Maneyro
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Phenotypic Plasticity ◽  
Life History Strategies ◽  
Clinal Variation ◽  
Size And Shape ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Morphological Differences

Intersexual morphological differences within a species occur in many traits, including body size and shape. Many processes that cause geographic variability in morphology have been proposed: population structure, phenotypic plasticity (environmental effects on development), and natural and/or sexual selection. Several hypotheses can explain patterns of sexual dimorphism in anurans, including natural or intra/inter-sexual selection, and differences in life history strategies between sexes. Limnomedusa macroglossa is considered a habitat specialist restricted to rocky outcrops in Brazil, Argentina, Paraguay, and Uruguay. We evaluated the extent of sexual (size and shape) dimorphism in L. macroglossa from Uruguay based on morphometrics and secondary sexual characteristics, while taking into account geographic variation. Sexual dimorphism in body size of adults was found, but multivariate analyses did not demonstrate the existence of significant differences in shape. There were also significant differences in body size and hind leg measurements among six hydrographic basins as a result from the phenotypic plasticity correlated with local temperature, representing a clinal variation along the latitudinal gradient of Uruguay. The sexual dimorphism found in body size is probably the consequence of higher growth rates and/or late sexual maturity in females, which favors larger body size for accommodating larger ovaries, and thus, higher reproductive output. 

scholarly journals Adaptation to a novel predator inDrosophila melanogaster: How well are we able to predict evolutionary responses?

2014 ◽  
Author(s):  
Michael DeNieu ◽  
William Pitchers ◽  
Ian Dworkin
Keyword(s):  
Natural Selection ◽  
Experimental Evolution ◽  
Phenotypic Selection ◽  
Ancestral Population ◽  
Wing Size ◽  
Short Term ◽  
Heritable Variation ◽  
Size And Shape ◽  
Evolutionary Trajectories ◽  
Short Term Prediction

Evolutionary theory is sufficiently well developed to allow for short-term prediction of evolutionary trajectories. In addition to the presence of heritable variation, prediction requires knowledge of the form of natural selection on relevant traits. While many studies estimate the form of natural selection, few examine the degree to which traits evolve in the predicted direction. In this study we examine the form of natural selection imposed by mantid predation on wing size and shape in the fruitfly,Drosophila melanogaster. We then evolve populations ofD. melanogasterunder predation pressure, and examine the extent to which wing size and shape have responded in the predicted direction. We demonstrate that wing form partially evolves along the predicted vector from selection, more so than for control lineages. Furthermore, we re-examined phenotypic selection after ~30 generations of experimental evolution. We observed that the magnitude of selection on wing size and shape was diminished in populations evolving with mantid predators, while the direction of the selection vector differed from that of the ancestral population for shape. We discuss these findings in the context of the predictability of evolutionary responses, and the need for fully multivariate approaches.

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