scholarly journals Non-reproductive male cane toads ( Rhinella marina ) withhold sex-identifying information from their rivals

2019 ◽  
Vol 15 (8) ◽  
pp. 20190462 ◽  
Author(s):  
Crystal Kelehear ◽  
Richard Shine
Keyword(s):  
Sexual Identity ◽  
Standardized Tests ◽  
Opportunity Cost ◽  
Cane Toad ◽  
Rhinella Marina ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Reproductive Male ◽  
Male Specific ◽  
Do So

A male cane toad ( Rhinella marina ) that mistakenly clasps another male (rather than a female) in a sexual embrace (amplexus) can be induced to dismount by a male-specific ‘release call'. Although that sex-identifying system can benefit both males in that interaction, our standardized tests showed that one-third of male cane toads did not emit release calls when grasped. Most of those silent males were small, had small testes relative to body mass, and had poorly developed secondary sexual characteristics. If emitting a release call is costly (e.g. by attracting predators), a non-reproductive male may benefit by remaining silent; other cues (such as skin rugosity) will soon induce the amplexing male to dismount, and the ‘opportunity cost’ to being amplexed (inability to search for and clasp a female) is minimal for non-reproductive males. Hence, male toads may inform other males about their sexual identity only when it is beneficial to do so.

scholarly journals Molecular Characterization and Functional Study of Insulin-Like Androgenic Gland Hormone Gene in the Red Swamp Crayfish, Procambarus clarkii

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 645 ◽  
Author(s):  
Linlin Shi ◽  
Shuxin Han ◽  
Jiamin Fei ◽  
Long Zhang ◽  
Jonathan W Ray ◽  
...  
Keyword(s):  
Procambarus Clarkii ◽  
Functional Study ◽  
Distribution Analysis ◽  
Androgenic Gland ◽  
Secondary Sexual Characteristics ◽  
Single Sex ◽  
Red Swamp Crayfish ◽  
Rnai Technology ◽  
Sexual Characteristics ◽  
Male Specific

The androgenic gland (AG) is a male-specific endocrine organ that controls the primary and secondary sexual characteristics in male crustaceans. More evidence indicates that the insulin-like androgenic gland hormone gene (IAG) is the key male sexual differentiation factor, particularly the application of RNA interference (RNAi) technology on IAG. In this study, the full-length cDNA of IAG (termed PcIAG) was isolated from the red swamp crayfish, Procambarus clarkii. Tissue distribution analysis showed that in addition to its expression in the AG of male P. clarkii, PcIAG was widely expressed in female tissues and other male tissues. The PcIAG protein was detected in the reproductive and nervous systems of adult male P. clarkii. Additionally, RNAi results showed that the PcIAG expression could be silenced efficiently, and the male sperm maturation and release possibly present a transient adverse interference at lower doses (0.1 μg/g and 1 μg/g) of PcIAG–dsRNA (PcIAG double-stranded RNA). Dramatically, the expression level of PcIAG increased sharply shortly after the injection of higher doses (5 μg/g and 10 μg/g) of PcIAG–dsRNA, which might accelerate the maturation and release of sperm. Moreover, the expression of PcSxl (P. clarkii Sex-lethal) was detected by Quantitative Real-Time PCR (qPCR) after the injection of PcIAG–dsRNA to explore whether the PcIAG gene regulates the PcSxl gene, and we found that the PcIAG did not directly regulate PcSxl in P. clarkii. The study could help accelerate the progress of PcIAG functional research and provide a useful reference for the single-sex selective breeding of P. clarkii.

scholarly journals Sexual Dimorphism in Aggression: Sex-Specific Fighting Strategies Across Species

2021 ◽  
Vol 15 ◽  
Author(s):  
Matias Pandolfi ◽  
Maria Florencia Scaia ◽  
Maria Paz Fernandez
Keyword(s):  
Aggressive Behavior ◽  
Genetic Architecture ◽  
Model Systems ◽  
Female Aggression ◽  
Vertebrate Species ◽  
Neuronal Circuitry ◽  
Secondary Sexual Characteristics ◽  
Intrasexual Aggression ◽  
Sexual Characteristics ◽  
Male Specific

Aggressive behavior is thought to have evolved as a strategy for gaining access to resources such as territory, food, and potential mates. Across species, secondary sexual characteristics such as competitive aggression and territoriality are considered male-specific behaviors. However, although female–female aggression is often a behavior that is displayed almost exclusively to protect the offspring, multiple examples of female–female competitive aggression have been reported in both invertebrate and vertebrate species. Moreover, cases of intersexual aggression have been observed in a variety of species. Genetically tractable model systems such as mice, zebrafish, and fruit flies have proven extremely valuable for studying the underlying neuronal circuitry and the genetic architecture of aggressive behavior under laboratory conditions. However, most studies lack ethological or ecological perspectives and the behavioral patterns available are limited. The goal of this review is to discuss each of these forms of aggression, male intrasexual aggression, intersexual aggression and female intrasexual aggression in the context of the most common genetic animal models and discuss examples of these behaviors in other species.

Behaviour and survivorship of a dasyurid predator (Antechinus flavipes) in response to encounters with the toxic and invasive cane toad (Rhinella marina)

2013 ◽  
Vol 35 (2) ◽  
pp. 136 ◽  
Author(s):  
Wiebke Kämper ◽  
Jonathan K. Webb ◽  
Mathew S. Crowther ◽  
Matthew J. Greenlees ◽  
Richard Shine
Keyword(s):  
Native Species ◽  
New South ◽  
A Priori ◽  
Population Declines ◽  
Cane Toad ◽  
Mammal Species ◽  
Rhinella Marina ◽  
South Wales ◽  
Australian Marsupial ◽  
Do So

Australia’s biogeographical isolation has rendered many endemic species vulnerable to invaders. The recent spread of the cane toad (Rhinella marina) has caused serious population declines for some predatory reptile and mammal species. To determine a priori whether or not cane toad poisoning endangers native species, we can test the fates of predators in laboratory trials. We investigated whether an Australian marsupial whose range is increasingly being occupied by cane toads (the yellow-footed antechinus, Antechinus flavipes) is at risk of toad poisoning by testing (1) whether yellow-footed antechinuses approach or attack cane toads and, if so, whether they die as a result; and (2) if they survive, whether they then learn to avoid toads in subsequent encounters. We also investigated the effects of sympatry with toads on the feeding response. In all, 58% of antechinuses from eastern New South Wales approached or attacked a toad (over 4 or 5 opportunities to do so, on successive nights), and none showed ill effects after doing so. Antechinuses that attacked (killed or ingested) toads rapidly learnt to avoid them. Antechinuses from toad-exposed populations ingested more toad flesh, but otherwise reacted in the same ways as did conspecifics from toad-free areas. Hence, the yellow-footed antechinus is unlikely to face population declines via toad poisoning.

Sex determination and Y chromosome constitutive heterochromatin

2019 ◽  
Vol 1 (1) ◽  
pp. 1-5
Author(s):  
Abyt Ibraimov
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Constitutive Heterochromatin ◽  
Sex Differentiation ◽  
Secondary Sexual Characteristics ◽  
Biological Meaning ◽  
Heterochromatin Block ◽  
Sexual Characteristics ◽  
Open Question ◽  
Efficient Elimination

In many animals, including us, the genetic sex is determined at fertilization by sex chromosomes. Seemingly, the sex determination (SD) in human and animals is determined by the amount of constitutive heterochromatin on Y chromosome via cell thermoregulation. It is assumed the medulla and cortex tissue cells in the undifferentiated embryonic gonads (UEG) differ in vulnerability to the increase of the intracellular temperature. If the amount of the Y chromosome constitutive heterochromatin is enough for efficient elimination of heat difference between the nucleus and cytoplasm in rapidly growing UEG cells the medulla tissue survives. Otherwise it doomed to degeneration and a cortex tissue will remain in the UEG. Regardless of whether our assumption is true or not, it remains an open question why on Y chromosome there is a large constitutive heterochromatin block? What is its biological meaning? Does it relate to sex determination, sex differentiation and development of secondary sexual characteristics? If so, what is its mechanism: chemical or physical? There is no scientifically sound answer to these questions.

Evaluation of Writing Assignments

2017 ◽  
Vol 6 (2) ◽  
pp. 214
Author(s):  
Anita Jokić
Keyword(s):  
Standardized Tests ◽  
Teaching And Learning ◽  
Task Completion ◽  
Writing Assignments ◽  
Listening Skill ◽  
Job Application ◽  
Written Assignments ◽  
Insight Into ◽  
Teacher’S Responsibilities ◽  
Do So

Teaching English as a foreign language is now one of the most important subjects in Croatian secondary schools since English is one of the three obligatory subjects at 'matura' - standardized tests which the seniors need to pass to graduate. Writing is one of the three parts of the EL exam, the other two being listening and reading. When learning a language, students start from listening skill, move on to speaking and reading and finally to most difficult skill to master: writing. Teaching and learning writing faces a lot of challenges since it requires a lot of time to practice and even more to evaluate and monitor progress. Teacher's responsibilities are to regularly provide opportunities to write, encourage students to learn from their mistakes and promote their success. In order to do so, students should be given clear instructions on evaluation/assessment and concise feedback. Since grading written assignments takes up a lot of time, the author proposes rubrics which can be used to assess various types of writing taught at secondary level (description of place/event/person, letters of complaint, job application, invitation, discursive/opinion/for-and-against essay etc.). Author suggests four fixed rubrics and subdivisions: Task completion, Cohesion / coherence, Grammar and Vocabulary. All rubrics and subdivisions are described in the paper. A survey was also conducted on a sample of 140 students and has given an insight into students’ opinion on importance of assessment and feedback and its influence on their progress.

Reproductive failure of the red shiner (Cyprinella lutrensis) after exposure to an exogenous estrogen

2010 ◽  
Vol 67 (11) ◽  
pp. 1730-1743 ◽  
Author(s):  
Michelle M. McGree ◽  
Dana L. Winkelman ◽  
Nicole  K.M.  Vieira ◽  
Alan  M.  Vajda
Keyword(s):  
Reproductive Success ◽  
Great Plains ◽  
Endocrine Disrupting Chemicals ◽  
Water Control ◽  
Secondary Sexual Characteristics ◽  
Cyprinella Lutrensis ◽  
The Us ◽  
Sexual Characteristics ◽  
Solvent Control ◽  
17Β Estradiol

Endocrine disrupting chemicals (EDCs) have been detected in surface waters worldwide and can lead to developmental and reproductive disruption in exposed fishes. In the US Great Plains, EDCs are impacting streams and rivers and may be causing adverse reproductive effects. To examine how estrogenic EDCs might affect reproductive success of plains fishes, we experimentally exposed male red shiners ( Cyprinella lutrensis ) to exogenous 17β-estradiol. We characterized the effects of estradiol on male gonadal histology and secondary sexual characteristics, determined whether exposure reduced reproductive success, and examined the effects of depuration. Adults were exposed to a mean concentration of 70 ng·L−1 estradiol, a solvent control, or a water control for at least 83 days. Male exposure to estradiol resulted in elevated plasma vitellogenin concentrations, changes in spermatogenesis, reduced mating coloration and tubercles, altered mating behaviors, and reduced reproductive success with no viable progeny produced. Reproductive endpoints improved upon depuration (28 days). Exposure to estradiol had significant adverse effects on red shiners, indicating that wild populations may face developmental and reproductive difficulties if they are chronically exposed to estradiol.

Insurgent Compensation: Evidence from Iraq

2013 ◽  
Vol 103 (3) ◽  
pp. 518-522 ◽  
Author(s):  
Benjamin W Bahney ◽  
Radha K Iyengar ◽  
Patrick B Johnston ◽  
Danielle F Jung ◽  
Jacob N Shapiro ◽  
...  
Keyword(s):  
Risk Premium ◽  
Opportunity Cost ◽  
Marginal Product ◽  
Unskilled Labor ◽  
Outside Options ◽  
Estimated Risk ◽  
Do So ◽  
Low Wages

Participating in insurgency is physically risky. Why do people do so? Using new data on 3,799 payments to insurgent fighters by Al Qa'ida Iraq, we find that: (i) wages were extremely low relative to outside options, even compared to unskilled labor; (ii) the estimated risk premium is negative; and (iii) the wage schedule favors equalization and provides additional compensation for larger families. These results challenge the notion that fighters are paid their marginal product, or the opportunity cost of their time. They may be consistent with a “lemons” model in which fighters signal commitment by accepting low wages.

Comparative urogenital morphology and external sex determination in muskellunge, Esox masquinongy Mitchill

1989 ◽  
Vol 67 (4) ◽  
pp. 1053-1060 ◽  
Author(s):  
Bernard Lebeau ◽  
Gérard Pageau
Keyword(s):  
Ventral Surface ◽  
Northern Pike ◽  
Structural Basis ◽  
Simple Method ◽  
Esox Masquinongy ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Spawning Behaviour ◽  
Accurate Indicator ◽  
Secondary Sexual

Primary and secondary sexual characteristics in northern pike, Esox lucius Linneaus, and muskellunge, Esox masquinongy Mitchill, differ markedly. Differences in the internal urogenital anatomy include the structure of the genital ducts and the angle they form with the ventral surface. Externally, the genital and urinary ducts open directly to the environment in northern pike, whereas in muskellunge they open into a muscular papilla and then through a urogenital pore. Differences in sexual dimorphism between the two closely related esocids constitute a structural basis to explain the known differences in spawning behaviour and reproductive success. Differences in secondary sexual characteristics explain why the methods developed by Demchenko or Casselman to externally sex pike are inapplicable to muskellunge. To develop and test two external sexing techniques for muskellunge, specimens were collected from two regions in Canada from 1980 to 1987. Examination of reproductive products obtained from stripping provided an accurate indicator of sex and sexual maturity, but demonstrated serious limitations. A simple method to sex muskellunge by examination of the external urogenital morphology is described for juveniles and adults. Dissection of fish revealed that with the urogenital examination technique we sexed juveniles with a success rate of 92–98%, and adults with 100% accuracy.

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