Reversed sexual dimorphism in the beak of a finch

The ecology and function of many Australian predators has likely been disrupted following major changes in prey base due to declines in distribution and abundance of small mammals following European settlement. This study investigated various aspects of the dietary ecology of sooty owls (Tyto tenebricosa tenebricosa), including sexual variation as they potentially exhibit the greatest degree of reversed sexual dimorphism of any owl species worldwide. Sooty owls are highly opportunistic predators of non-volant small mammals, consuming most species known to exist in the region, so their diet fluctuates seasonally and spatially due to varying prey availability, and is particularly influenced by the breeding cycles of prey. Significant intersexual dietary differences existed with female sooty owls predominantly consuming much larger prey items than males, with dietary overlap at 0.62. The current reliance on relatively few native mammalian species is of conservation concern, especially when mammal declines are unlikely to have ceased as many threatening processes still persist in the landscape. Sooty owl conservation appears inextricably linked with small mammal conservation. Conservation efforts should be focussed towards improving prey densities and prey habitat, primarily by implementing control programs for feral predators and preventing the loss of hollow-bearing trees throughout the landscape.

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A new miniature Pristella (Actinopterygii: Characiformes: Characidae) with reversed sexual dimorphism from the rio Tocantins and rio São Francisco basins, Brazil

Canadian Journal of Zoology ◽

10.1139/cjz-2020-0241 ◽

2021 ◽

pp. 339-348

Author(s):

F.C.T. Lima ◽

R.A. Caires ◽

C.C. Conde-Saldaña ◽

J.M. Mirande ◽

F.R. Carvalho

Keyword(s):

Phylogenetic Analysis ◽

New Species ◽

Sexual Dimorphism ◽

Color Pattern ◽

Bony Fishes ◽

Reversed Sexual Dimorphism ◽

A New Species

A new species of the genus Pristella Eigenmann, 1908 (Pristella crinogi sp. nov.) is described from the middle rio Tocantins and middle rio São Francisco basins, Brazil. The new species can be diagnosed from its two congeners, Pristella ariporo Conde-Saldaña, Albornoz-Garzón, García-Melo, Villa-Navarro, Mirande, and Lima, 2019 and Pristella maxillaris (Ulrey, 1894), by a combination of color pattern and teeth morphology characters. A phylogenetic analysis of the genus recovered P. crinogi as the sister taxa of P. ariporo. Pristella crinogi, along with P. ariporo, are the first characiform fishes, and one of the first bony fishes, to be reported as presenting a reversed sexual dimorphism, with females presenting a more developed color pattern than males. Comments on the miniaturization of the species, as well as remarks on the biogeography of the genus Pristella, are presented.

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A Comparative Study of the Canine Tooth as a Tool in Gender Determination in Nigerian Population

Galician Medical Journal ◽

10.21802/gmj.2019.2.9 ◽

2019 ◽

Vol 26 (2) ◽

Author(s):

Peter O Otuaga ◽

Lilian Ebite Chris-Ozoko ◽

Oghenetega Lynda Sakpoba ◽

John Chukwuma Oyem

Keyword(s):

Sexual Dimorphism ◽

Sex Determination ◽

Canine Tooth ◽

Maxillary Canine ◽

Male And Female ◽

Study Results ◽

Significant Difference ◽

Nigerian Population ◽

Reversed Sexual Dimorphism ◽

Dental Evidence

Dental evidence has been demonstrated as a major forensic tool for the identification of individuals and sex determination. The objective of the research was to determine sex in Delta Ibo ethnic group of Nigeria using the mandibular and maxillary canine teeth. Materials and methods. The study comprised 201 (100 males and 101 females) subjects of Delta Ibo ethnicity at the age of 17 – 25 years. The mesiodistal crown width and intercanine distance of both the maxillary and mandibular canines were measured intraorally using a pair of dividers and a ruler. Unpaired T-test at a probability value of p<0.05 was used to ascertain the mean significant differences between the male and female canine indices. Results. Study results showed a statistically significant difference between male and female mandibular and maxillary canine mesiodistal width. This implied a sexual and reversed sexual dimorphism in the studied population. Conclusions. The study confirmed that the canines of Delta Ibos exhibit sexual dimorphism like other populations and the maxillary canine indices give the most accurate prediction in sex determination.

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Effects of hypophysectomy and growth hormone infusion on rat hepatic carbonic anhydrases

Journal of Endocrinology ◽

10.1677/joe.0.1100123 ◽

1986 ◽

Vol 110 (1) ◽

pp. 123-126 ◽

Cited By ~ 21

Author(s):

S. Jeffery ◽

C. A. Wilson ◽

A. Mode ◽

J.-Å. Gustafsson ◽

N. D. Carter

Keyword(s):

Growth Hormone ◽

Sexual Dimorphism ◽

Carbonic Anhydrase ◽

Sexual Differentiation ◽

Isozyme Pattern ◽

Male Rats ◽

Carbonic Anhydrases ◽

Reversed Sexual Dimorphism ◽

Normal Males ◽

Soluble Carbonic Anhydrase

ABSTRACT Rat liver exhibits a reversed sexual dimorphism of its two endogenous soluble carbonic anhydrase (CA) isozymes, CA II and CA III. Normal males have hepatic CA III concentrations ten–twenty times those in the female, while female liver contains two–three times more CA II than the male. Hypophysectomy abolishes this sexual differentiation, having no effect on male liver but producing isozyme concentrations in the female liver similar to those in the male. Infusion of a continuous level of GH into male rats induces a female-like isozyme pattern for both CA II and CA III. J. Endocr. (1986) 110, 123–126

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