Sexual Dimorphism in Head Shape, Relative Head Width, and Body Size of<i>Eurycea aquatica</i>and<i>Eurycea cirrigera</i>

Alcorn, Michael A.; Deitloff, Jennifer; Graham, Sean P.; Timpe, Elizabeth K.

doi:10.1670/11-317

Cited by 19 publications

(7 citation statements)

References 39 publications

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“…This decrease in the degree of dimorphism in the other species is the result of adult females having hypertrophied jaw muscles, similar to adult males, rather than the ancestral state of no jaw muscle hypertrophy in either sex. While males of a few other plethodontid species have hypertrophied jaw muscles, it tends to be a species-specific characteristic (e.g., Eurycea aquatica, Eurycea cirrigera [ Alcorn et al. 2013 ], Eurycea wilderae [ Sever 1979 ; Pierson et al.…”

Section: Discussionmentioning

confidence: 99%

The Evolution of Derived Monomorphism From Sexual Dimorphism: A Case Study on Salamanders

Staub

2020

Integrative Organismal Biology

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While sexual dimorphism has long received special attention from biologists, derived monomorphism, the condition in which both males and females express similar derived features, has been less well studied. Historically, the appearance of “male-like” features in females has been explained by the genetic correlation between the sexes. Recent work emphasizes the importance of studying the independent selective forces on both females and males to understand sexual dimorphism. Sexual dimorphism and derived monomorphism in the genus Aneides are examined in light of predictions of social selection. Aneides hardii shows the greatest degree of sexual dimorphism in snout-vent length and head width, with the other species of Aneides less sexually dimorphic. This reduced dimorphism, however, is not a return to an ancestral monomorphic state, but rather exemplifies derived monomorphism because females express traits that were limited in expression to males of ancestral species. Instead of calling these “male-typical” traits in females, I suggest the term “derived monomorphic” traits, as these traits are typical in these females and “derived monomorphic” can apply to both sexes. Increased attention to studying the patterns and ecological significance of derived monomorphism will shed light on the underlying selective forces, including sexual selection, on both females and males.

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Section: Discussionmentioning

confidence: 99%

The Evolution of Derived Monomorphism From Sexual Dimorphism: A Case Study on Salamanders

Staub

2020

Integrative Organismal Biology

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“…Sexual dimorphism of secondary sexual characters has been observed in many studies of plethodontid salamanders (Alcorn, Deitloff, Graham, & Timpe, 2013;Noble, 1929;Sever, 1985Sever, , 1989and others). Males in some species of plethodontid salamanders possess glands on the chin and dorsal base of the tail that are used in courtship and are thought to keep females more receptive throughout the process of fertilization, during the tail-straddle walk and spermatophore deposition (Noble, 1927(Noble, , 1929.…”

Section: Introductionmentioning

confidence: 88%

Histology of mental and caudal courtship glands in three genera of plethodontid salamanders (Amphibia: Plethodontidae)

Rupp

Sever

2017

Acta Zoologica

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Salamanders in the family Plethodontidae exhibit a unique tail‐straddle walk during courtship that can include the use of sexually dimorphic mental and caudal courtship glands. This study presents novel histological and fine structure data on mental glands and caudal courtship glands in Plethodon mississippi, Desmognathus conanti and Eurycea quadridigitata using both light microscopy and scanning electron microscopy. This study represents the first use of scanning electron microscopy to observe these glands. Both mental and caudal courtship glands were observed to vary seasonally in gland diameter and histology according to the breeding season of each species. Morphological variation was observed across the three species studied in both clustering and relative size of the glands compared to neighbouring mucous and granular glands. Hypertrophied mental glands are larger than mucous or granular glands in all species, but relationships among caudal courtship glands and other skin glands vary among species. In E. quadridigitata, active caudal courtship glands are larger than mucous and granular glands, but in D. conanti, caudal courtship glands are similar in size to granular glands and larger than mucous glands. In P. mississippi, caudal courtship glands are scattered among significantly larger granular glands and are similar in size to mucous glands.

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“…First, the methodological procedure introduced allowed us to identify shape differences between the sexes, although these are known to be very subtle in Salamandra salamandra and had been scarcely studied in the past. The same occurs in most urodeles, in which sexual dimorphism in size has been broadly addressed, whereas sexual dimorphism in shape remains much less studied (e.g., Romano et al, 2009;Labus et al, 2012Labus et al, , 2013Alcorn et al, 2013;Reinhard et al, 2015). The study of proportions has highlighted the presence of sexual shape dimorphism in several urodeles with weak differentiation between the sexes (Romano et al, 2009;Amat et al, 2015), even though its effectiveness in detecting shape variation could be too dependent of the structure or traits under study (Fabre et al, 2014).…”

Section: Biological Shape Variationmentioning

confidence: 99%

“…While the study of the cranium of both anurans and urodeles has been very fruitful for understanding sources of head shape variation in the dorso‐ventral direction, the procedures required for obtaining cranial elements are prohibitive when working with museum specimens and above all with living individuals from natural populations. To the best of our knowledge, only one study has applied GM to the analysis of external ventral head shape in urodeles (Alcorn et al, ), giving clues of the potential of the exploration of external head shape in these organisms.…”

Section: Introductionmentioning

confidence: 99%

A non-invasive geometric morphometrics method for exploring variation in dorsal head shape in urodeles: sexual dimorphism and geographic variation inSalamandra salamandra

Alarcón-Ríos

Velo‐Antón

Kaliontzopoulou

2017

Journal of Morphology

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The study of morphological variation among and within taxa can shed light on the evolution of phenotypic diversification. In the case of urodeles, the dorso-ventral view of the head captures most of the ontogenetic and evolutionary variation of the entire head, which is a structure with a high potential for being a target of selection due to its relevance in ecological and social functions. Here, we describe a non-invasive procedure of geometric morphometrics for exploring morphological variation in the external dorso-ventral view of urodeles' head. To explore the accuracy of the method and its potential for describing morphological patterns we applied it to two populations of Salamandra salamandra gallaica from NW Iberia. Using landmark-based geometric morphometrics, we detected differences in head shape between populations and sexes, and an allometric relationship between shape and size. We also determined that not all differences in head shape are due to size variation, suggesting intrinsic shape differences across sexes and populations. These morphological patterns had not been previously explored in S. salamandra, despite the high levels of intraspecific diversity within this species. The methodological procedure presented here allows to detect shape variation at a very fine scale, and solves the drawbacks of using cranial samples, thus increasing the possibilities of using collection specimens and alive animals for exploring dorsal head shape variation and its evolutionary and ecological implications in urodeles. J. Morphol. 278:475-485, 2017. © 2017 Wiley Periodicals, Inc.

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Sexual Dimorphism in Head Shape, Relative Head Width, and Body Size ofEurycea aquaticaandEurycea cirrigera

Cited by 19 publications

References 39 publications

The Evolution of Derived Monomorphism From Sexual Dimorphism: A Case Study on Salamanders

The Evolution of Derived Monomorphism From Sexual Dimorphism: A Case Study on Salamanders

Histology of mental and caudal courtship glands in three genera of plethodontid salamanders (Amphibia: Plethodontidae)

A non-invasive geometric morphometrics method for exploring variation in dorsal head shape in urodeles: sexual dimorphism and geographic variation inSalamandra salamandra

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