Population variation in skeletal sexual dimorphism

2017 ◽  
Vol 278 ◽  
pp. 407.e1-407.e7 ◽  
Author(s):  
Douglas H. Ubelaker ◽  
Cassandra M. DeGaglia
Keyword(s):  
Sexual Dimorphism ◽  
Population Variation

scholarly journals Phenotypic Variation in Skull Size and Shape Between Newfoundland and Mainland Populations of North American Black Bears, Ursus americanus

2003 ◽  
Vol 117 (2) ◽  
pp. 236 ◽  
Author(s):  
John A. Virgl ◽  
Shane P. Mahoney ◽  
Kim Mawhinney
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Ursus Americanus ◽  
Population Variation ◽  
Black Bears ◽  
Selection Pressures ◽  
Skull Shape ◽  
Skull Size ◽  
Environmental Selection ◽  
Gape Size

It is well recognized that differences in environmental selection pressures among populations can generate phenotypic divergence in a suite of morphological characteristics and associated life history traits. Previous analysis of mitochondrial DNA and body size have suggested that Black Bears (Ursus americanus) inhabiting the island of Newfoundland represent a different subspecies or ecotype from mainland populations. Assuming that body size covaries positively with skull size, we predicted that skull size would be greater for bears on the island than the mainland, and the distribution of size-related shape components in multivariate space should show a distinct separation between Newfoundland and mainland populations. Measurements of 1080 specimens from Newfoundland, Alberta, New York, and Quebec did not provide unequivocal support for our prediction that skull size in Newfoundland bears would be larger than bears from the mainland populations. After removing ontogenetic effects of skull size, between-population variation in skull shape was greater in females than males, and the analysis significantly separated Newfoundland bears from mainland populations. Explanations for this pattern are numerous, but currently remain hypothetical. Limited covariation between skull size and body size suggests that genetic traits regulating the size of Black Bear skulls are more heritable (i.e., less influenced by environmental selection pressures) than characteristics affecting body size. We hypothesize that if gape size does not limit prey size in solitary terrestrial carnivores, large degrees of among-population variation in body size should be coupled with little covariation in skull size. In general, sexual dimorphism in skull size and shape was marginal for the phenotypic characters measured in our study. We believe that sexual dimorphism in skull size in Black Bears is primarily driven by intrasexual selection in males for increased gape size display, while similarity in skull shape between sexes is associated with the constraints of a temporally-selective, but similar diet.

scholarly journals Intra-Specific Venom Variation in the Australian Coastal Taipan Oxyuranus scutellatus

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 485 ◽  
Author(s):  
Theo Tasoulis ◽  
Anjana Silva ◽  
Punnam Chander Veerati ◽  
Mark Baker ◽  
Wayne C. Hodgson ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Snake Venom ◽  
Geographical Variation ◽  
East Coast ◽  
Population Variation ◽  
The Other ◽  
North East ◽  
The North ◽  
Specific Variation ◽  
Two Populations

Intra-specific venom variation has the potential to provide important insights into the evolution of snake venom, but remains a relatively neglected aspect of snake venom studies. We investigated the venom from 13 individual coastal taipans Oxyuranus scutellatus from four localities on the north-east coast of Australia, spanning a distance of 2000 km. The intra-specific variation in taipan venom was considerably less than the inter-specific variation between it and the other Australian elapids to which it was compared. The electrophoretic venom profile of O. scutellatus was visually different to six other genera of Australian elapids, but not to its congener inland taipan O. microlepidotus. There was minimal geographical variation in taipan venom, as the intra-population variation exceeded the inter-population variation for enzymatic activity, procoagulant activity, and the abundance of neurotoxins. The pre-synaptic neurotoxin (taipoxin) was more abundant than the post-synaptic neurotoxins (3FTx), with a median of 11.0% (interquartile range (IQR): 9.7% to 18.3%; range: 6.7% to 23.6%) vs. a median of 3.4% (IQR: 0.4% to 6.7%; range: 0% to 8.1%). Three taipan individuals almost completely lacked post-synaptic neurotoxins, which was not associated with geography and occurred within two populations. We found no evidence of sexual dimorphism in taipan venom. Our study provides a basis for evaluating the significance of intra-specific venom variation within a phylogenetic context by comparing it to the inter-specific and inter-generic variation. The considerable intra-population variation we observed supports the use of several unpooled individuals from each population when making inter-specific comparisons.

Worldwide population variation in pelvic sexual dimorphism: A validation and recalibration of the Klales et al. method

2017 ◽  
Vol 277 ◽  
pp. 259.e1-259.e8 ◽  
Author(s):  
Michael W. Kenyhercz ◽  
Alexandra R. Klales ◽  
Kyra E. Stull ◽  
Kyle A. McCormick ◽  
Stephanie J. Cole
Keyword(s):  
Sexual Dimorphism ◽  
Population Variation ◽  
Worldwide Population ◽  
Pelvic Sexual Dimorphism

Population variation in sexual dimorphism in the human innominate

1986 ◽  
Vol 1 (3) ◽  
pp. 221-231 ◽  
Author(s):  
S. M. MacLaughlin ◽  
M. F. Bruce
Keyword(s):  
Sexual Dimorphism ◽  
Population Variation

Intraspecific variations in morphology of swamp barb (Puntius brevis)

2021 ◽  
Vol 13 (Aquaculture) ◽  
pp. 44-51
Author(s):  
Ngoc Son Le ◽  
Thuy Yen Duong
Keyword(s):  
Sexual Dimorphism ◽  
Intraspecific Variation ◽  
Mekong Delta ◽  
Population Variation ◽  
External Morphology ◽  
Biological Research ◽  
Egg Carrying ◽  
Fundamental Part ◽  
Intraspecific Variations ◽  
Fin Length

Understanding inter-population variation and sexual differences in morphology is a fundamental part of taxonomic and biological research. External morphology of swamp barb (Puntius brevis) was compared between sexes and among three populations in the Mekong Delta, including O Mon-Can Tho (n=86), U Minh Thuong-Kien Giang (n=49) and U Minh Ha-Ca Mau (n=77). The results illustrate that color and countable parameters are similar in all populations. Nonetheless, 9 out of 20 morphometric indices are significantly different among three populations (P<0.05), where 6 indices are more important criteria to distinguish among swamp barb populations. Furthermore, the sexual dimorphism of this species is indicated in 16/20 morphometric indices consisting of 5 indices relating egg-carrying characteristics. In particular, the females have higher values of indices relating to abdomen and head parts while most of fin length indices are larger in males than in females. In sum, intraspecific variation in morphometrics of swamp barb is mainly due to sexual dimorphism rather than populations.

RHYNCHOLITES AND THE PROBLEM OF NARROW AND BROAD CONCEPTION OF TAXONS

2018 ◽  
pp. 12-17 ◽  
Author(s):  
I. R. Khuzina ◽  
V. N. Komarov
Keyword(s):  
Sexual Dimorphism ◽  
Morphological Characteristics ◽  
Mass Scale ◽  
Individual Variability ◽  
Point Of View ◽  
The Other ◽  
New Taxon ◽  
Artificial System ◽  
Broad Understanding

The paper considers a point of view, based on the conception of the broad understanding of taxons. According to this point of view, rhyncholites of the subgenus Dentatobeccus and Microbeccus are accepted to be synonymous with the genus Rhynchoteuthis, and subgenus Romanovichella is considered to be synonymous with the genus Palaeoteuthis. The criteria, exercising influence on the different approaches to the classification of rhyncholites, have been analyzed (such as age and individual variability, sexual dimorphism, pathological and teratological features, degree of disintegration of material), underestimation of which can lead to inaccuracy. Divestment of the subgenuses Dentatobeccus, Microbeccus and Romanovichella, possessing very bright morphological characteristics, to have an independent status and denomination to their synonyms, has been noted to be unjustified. An artificial system (any suggested variant) with all its minuses is a single probable system for rhyncholites. The main criteria, minimizing its negative sides and proving the separation of the new taxon, is an available mass-scale material. The narrow understanding of the genus, used in sensible limits, has been underlined to simplify the problem of the passing the view about the genus to the other investigators and recognition of rhyncholites for the practical tasks.

Parental breeding age effects on descendants’ longevity interact over two generations in matrilines and patrilines

2019 ◽  
Author(s):  
Zac Wylde ◽  
Foteini Spagopoulou ◽  
Amy K Hooper ◽  
Alexei A Maklakov ◽  
Russell Bonduriansky
Keyword(s):  
Maternal Age ◽  
First Generation ◽  
Age Effects ◽  
Population Variation ◽  
Paternal Age ◽  
Interactive Effects ◽  
Competitive Environment ◽  
Larval Diet ◽  
Negative Effects ◽  
Two Generations

Individuals within populations vary enormously in mortality risk and longevity, but the causes of this variation remain poorly understood. A potentially important and phylogenetically widespread source of such variation is maternal age at breeding, which typically has negative effects on offspring longevity. Here, we show that paternal age can affect offspring longevity as strongly as maternal age does, and that breeding age effects can interact over two generations in both matrilines and patrilines. We manipulated maternal and paternal ages at breeding over two generations in the neriid fly Telostylinus angusticollis. To determine whether breeding age effects can be modulated by the environment, we also manipulated larval diet and male competitive environment in the first generation. We found separate and interactive effects of parental and grandparental ages at breeding on descendants’ mortality rate and lifespan in both matrilines and patrilines. These breeding age effects were not modulated by grandparental larval diet quality or competitive environment. Our findings suggest that variation in maternal and paternal ages at breeding could contribute substantially to intra-population variation in mortality and longevity.

Sign in / Sign up

Export Citation Format

Share Document