Sexual dichromatism in the marbled salamander, Ambystoma opacum

2007 ◽  
Vol 85 (9) ◽  
pp. 1008-1013 ◽  
Author(s):  
Brian D. Todd ◽  
Andrew K. Davis
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Relative Proportion ◽  
Dorsal Surface ◽  
Sexual Dichromatism ◽  
Sexually Dimorphic ◽  
Ambystoma Opacum ◽  
Males And Females ◽  
Marbled Salamander ◽  
Image Analysis Techniques

Reports of sexual dichromatism in salamanders are rare and have been generally restricted to a few species in the families Hynobiidae and Salamandridae. We used image analysis techniques to examine sexual dichromatism in the marbled salamander, Ambystoma opacum (Gravenhorst, 1807). We measured the average hue of white saddles on male and female marbled salamanders (n = 118), as well as the proportion of white dorsal surface area relative to the black dorsal surface area, to determine the extent of sexual dichromatism in this species. We also tested whether patterning and coloration were correlated with body size or relative body mass. Males had significantly whiter saddles and higher relative proportions of white coloration on their dorsal surfaces than did females. Furthermore, the relative proportion of white areas on the dorsum was positively correlated to body condition in both males and females. Body size was not correlated with hue or proportion of white area on the dorsum. To our knowledge, we report the first confirmation of sexually dimorphic coloration in the ambystomatid salamander family, extending the known distribution of sexual dichromatism in the order Caudata.

Body size, not age, predicts parasite load in Clark’s Spiny Lizards (Sceloporus clarkii)

2019 ◽  
Vol 97 (3) ◽  
pp. 220-224 ◽  
Author(s):  
H.V. Watkins ◽  
G. Blouin-Demers
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Intraspecific Variation ◽  
Wild Population ◽  
Parasite Load ◽  
Older Individuals ◽  
Fundamental Goal ◽  
Males And Females ◽  
Ectoparasite Load

Determining the factors that influence parasite load is a fundamental goal of parasitology. Body size often influences parasite load in reptiles, but it is unclear whether higher levels of parasitism are a result of greater surface area of individuals (a function of size) or of longer periods of exposure to parasites (a function of age). Using skeletochronology in a wild population of Clark’s Spiny Lizards (Sceloporus clarkii Baird and Girard, 1852), we tested the hypotheses that (i) larger individuals have higher parasite loads due to increased surface area available for colonization by parasites and their vectors and that (ii) older individuals have higher parasite loads because they have had longer exposure to parasites and their vectors. Males harboured more ectoparasites than females. Males and females differed in how body size influenced chigger (Acari: Trombiculidae) load; larger males harboured more chiggers than smaller males, but this was not the case in females. Age did not affect ectoparasite load in either sex. These results emphasize the importance of disentangling the effects of size and age in models of parasitism to gain a clearer understanding of intraspecific variation in parasite load.

Relationship of larval density and heterozygosity to growth and survival of juvenile marbled salamanders (Ambystoma opacum)

1996 ◽  
Vol 74 (6) ◽  
pp. 1122-1129 ◽  
Author(s):  
Anne C. Chazal ◽  
John D. Krenz ◽  
David E. Scott
Keyword(s):  
Body Size ◽  
Larval Density ◽  
Larval Growth ◽  
Adult Survival ◽  
Growth And Survival ◽  
Ambystoma Opacum ◽  
Size At Metamorphosis ◽  
Body Sizes ◽  
Marbled Salamander ◽  
Relationship Of

Intraspecific competition and enzyme variability have been observed to influence the bioenergetics of many organisms. In amphibians, larval growth affects body size at metamorphosis, which in turn can lead to differences in adult survival and fecundity. We manipulated larval density in a population of the marbled salamander, Ambystoma opacum, and measured body size and enzyme variability in surviving newly metamorphosed juveniles. Crowded larval conditions resulted in lower survival and smaller body sizes at metamorphosis. Multilocus heterozygosity showed no relation to body size at high larval densities; however, at low larval densities relatively homozygous animals were larger. There was a significant interaction between heterozygosity and larval density in their effects on larval traits. Competition had a greater effect on body size at metamorphosis than did heterozygosity. Survival may be enhanced by heterozygosity but in a manner unrelated to body size.

The link between sexual dimorphism, activity budgets, and group cohesion: the case of the plains zebra (Equus burchelli)

2002 ◽  
Vol 80 (8) ◽  
pp. 1437-1441 ◽  
Author(s):  
P Neuhaus ◽  
K E Ruckstuhl
Keyword(s):  
Body Size ◽  
Reproductive Status ◽  
Sexually Dimorphic ◽  
Time Budgets ◽  
Activity Budgets ◽  
Equus Burchelli ◽  
Lactating Females ◽  
Males And Females ◽  
Reproductive Females ◽  
Dimorphic Species

Animals that differ in reproductive status and body size have different needs in terms of foraging and resting. In most social ungulates this leads to sexual segregation, probably because of incompatibilities between the activity budgets of males and females. Since most studies on behavioural differences between the sexes have been done on sexually dimorphic species, we decided to look at a system in which males and females are similar in body size. We studied time budgets, synchrony of behaviour, and bite rates of plains zebras (Equus burchelli) to evaluate the factors that enable these extremely social ungulates to stay in stable mixed-sex family groups throughout the year. As we predicted, time budgets were similar among males, lactating females, pregnant females, and non-reproductive females. Furthermore, we observed close synchronization of behaviours between females that differed in reproductive status and males. Lactating females, however, did take more bites per minute when foraging than either pregnant or non-reproducing females or males. We assume that the higher bite rates of lactating females were due to the extra costs of producing milk for their foal. We concluded that the special harem mating system, and for females the year-round possibility of conceiving, force the animals to synchronize their time budgets, which might be a major reason for the lack of difference in body size between males and females.

scholarly journals Differences in Pelvic Fin Length Represent Sexual Dimorphism in Utah Chub (Gila atraria)

2014 ◽  
Vol 7 (1) ◽  
pp. 42-45 ◽  
Author(s):  
Mark C. Belk ◽  
Scott Bird ◽  
Mehmet Cemal Oguz ◽  
Jerald B. Johnson
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Cyprinid Fish ◽  
Sexually Dimorphic ◽  
Adaptive Function ◽  
Males And Females ◽  
The Difference ◽  
Sexually Mature ◽  
Fin Length ◽  
Pelvic Fin

The cyprinid fish Gila atraria Girard (Utah chub) is generally considered a sexually monomorphic species. However, prior observations revealed variation in pelvic fin length within populations that appears sexually dimorphic. We measured the relative pelvic fin length of 419 sexually mature Utah chub from 8 different locations to determine the magnitude and generality of this apparent dimorphism. Pelvic fin length in G. atraria differs between sexes by about 10% on average; males have longer pelvic fins than females. The dimorphism is general across all locations, but it is not related to body size. Magnitude of the dimorphism varies by predation environment – the difference between males and females is slightly greater in low predation environments. We find no evidence for an adaptive function for this dimorphism; however, it does provide an efficient mechanism for determining sex without dissection.

Diving behaviour of male and female western grebes

1988 ◽  
Vol 66 (12) ◽  
pp. 2695-2698 ◽  
Author(s):  
L. Scott Forbes ◽  
Spencer G. Sealy
Keyword(s):  
British Columbia ◽  
Body Size ◽  
Water Depth ◽  
Wave Action ◽  
Diving Behaviour ◽  
Sexually Dimorphic ◽  
Habitat Conditions ◽  
Male And Female ◽  
Males And Females

We studied diving in western grebes (Aechmophorus occidentalis), which are sexually dimorphic, at Duck and Kootenay lakes in southeastern British Columbia to determine if differences in sex, and hence body size, resulted in differences in behaviour. Springing dives were used more frequently in deeper water and when wave action was higher, but there were no clear differences between males and females. As well, the dive–pause regressions for males and females did not differ. We conclude that differences in body size are not important determinants of diving behaviour in western grebes, but that habitat conditions (e.g., water depth, wave action) are.

scholarly journals Sexual Dimorphism in Eye Morphology in a Butterfly (Asterocampa leilia; Lepidoptera, Nymphalidae)

2000 ◽  
Vol 103 (1-2) ◽  
pp. 25-36 ◽  
Author(s):  
Kristine S. Ziemba ◽  
Ronald L. Rutowski
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Visual Field ◽  
Surface Area ◽  
Sexual Differences ◽  
Corneal Surface ◽  
Mate Searching ◽  
Eye Morphology ◽  
Eye Size ◽  
Males And Females

In the Empress Leilia butterfly,Asterocampa leilia, as in many insects, males have larger eyes than females. We explore the morphological causes and consequences of this dimorphism in eye size by comparing the corneal surface area, facet numbers, and patterns of variation in facet dimensions in males and females. We report that, with body size (measured by forewing length) controlled, male eyes are consistently larger than female eyes, and that, although males and females do not differ significantly in the number of facets per eye, males have significantly larger facets. Also, males have disproportionately larger facets both frontally and dorsally. As a result of these sexual differences in eye structure, males are expected to have a larger and more acute visual field than females which could be advantageous in the context of this species' mate searching tactic.

Disrupting information alters the behavioral response to a mutual signal trait in both sexes of Nicrophorus (Coleoptera: Silphidae) burying beetles

2019 ◽  
Vol 30 (4) ◽  
pp. 960-967
Author(s):  
Jillian D Wormington ◽  
Barney Luttbeg
Keyword(s):  
Body Size ◽  
Behavioral Responses ◽  
Reproductive Investment ◽  
Sexually Dimorphic ◽  
Burying Beetles ◽  
Signaling Function ◽  
Opposite Sex ◽  
Nicrophorus Orbicollis ◽  
Males And Females ◽  
Competition For Resources

AbstractEffective signals transfer information in a way that enhances the fitness of the sender. Signal traits are often sexually dimorphic. However, in some species, males and females display similar signals, and these mutual signals are less often studied. Competition for resources occurs in both males and females, and mate choice is likely to occur whenever mates vary in quality and reproductive investment is high. Nicrophorus burying beetles compete intrasexually over the carrion resources on which they biparentally raise their young. Nicrophorus species also often have clypeal membranes which scale hyperallometrically with body size, exaggerating the apparent body size of larger individuals. To examine the potential signaling function of clypeal membranes, we examined the behavioral responses of male and female Nicrophorus orbicollis and Nicrophorus pustulatus burying beetles to same- and opposite-sex social partners which had their membranes painted black or clear. We found evidence that blocking the information in clypeal membranes affected intrasexual aggressive interactions for both sexes of both species. Blocking a female’s signal reduced the likelihood of mating attempts for male N. pustulatus, whereas blocking a male’s signal influenced female rejection behaviors in N. orbicollis. Our results show that males and females can experience similar selection pressures, and suggest that examining mutual signals in a broader range of systems will expand our understanding of evolutionary differences and similarities between the sexes.

Morphometrics and molecular analysis ofOzolaimus linstowin. sp. (Oxyuroidea: Pharyngodonidae) from the green lizardIguana iguana

2015 ◽  
Vol 90 (2) ◽  
pp. 186-198 ◽  
Author(s):  
S.V. Malysheva
Keyword(s):  
Body Size ◽  
Large Subunit ◽  
Buccal Capsule ◽  
Small Subunit ◽  
Present Species ◽  
Lsu Rdna ◽  
Adult Males ◽  
Spicule Length ◽  
Males And Females ◽  
Characteristic Features

AbstractOzolaimus linstowin. sp. is described from the large intestine ofIguana iguanaLinnaeus, 1758 from Mexico. The present species can be easily distinguished fromO. megatyphlonandO. cirratusby the presence of a long and slender pharynx not divided into sections, more similar to the remaining two species,O. monhysteraandO. ctenosauri. Ozolaimus linstowin. sp. can be differentiated fromO. monhysteraby the shorter spicule length and smaller body size of both males and females. Males ofO. linstowin. sp. are morphologically close to those ofO. ctenosauri, but females possess a markedly smaller body size and differ in the organization of the oral cuticular armature. Adult males ofO. linstowin. sp. bear some characteristic features of the J3 juvenile morphology in terms of the cuticular organization of the oral and buccal capsule. Phylogenetic analysis ofO.linstowin. sp. using partial small subunit (SSU) and D2–D3 large subunit (LSU) rDNA shows relationships with several Oxyuridae genera.

Variation in Weight, Size, and Sex Ratio of Coccinellid Adults (Coleoptera: Coccinellidae)

1966 ◽  
Vol 98 (6) ◽  
pp. 639-644 ◽  
Author(s):  
B. C. Smith
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Water Content ◽  
Food Supply ◽  
Sexual Differences ◽  
Intraspecies Variation ◽  
Food Scarcity ◽  
Food Requirement ◽  
Males And Females

AbstractThe weight and size of coccinellid adults varied with species, sex, and feeding. Intraspecies variation in weight was generally similar in the eight species studied. Females were more variable than males in body size. Females of some species were heavier and larger than males, and species can be classified on a basis of difference in the weight and size of the sexes.An increase in the food supply after a period of food scarcity affected the sex ratio, as the minimum food requirement of females was greater than males. Females increased in weight more rapidly than males after feeding. The availability of food in the field affected the weight and size of some species. Adult water content was influenced by feeding but not by sex or the quantity of food given to the larva.Males were more abundant in species with small sexual differences in weight and size. The degree of difference in weight and size between males and females may be used as a criterion to select species that are best adapted to survive when food is scarce.

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