How Dragonflies Males Find and Mate with Females

Dragonfly sex is a rough-and-tumble affair. If youve ever seen a pair of mating dragonflies in the act, you know that their sexual coupling requires the flexibility and acrobatic skill of a Cirque de Soleil performer. Females get bitten, males get scratched, and sperm winds up everywhere. These strange mating habits have survived millions of years of evolution, so the dragonflies must know what theyre doing, right? Lets take a closer look at how dragonflies mate. How Dragonfly Males Find Receptive  Females Dragonflies dont engage in elaborate courtship rituals. In a few dragonfly families, the male might display his colors or fly over his territory to show a potential mate what a good oviposition site hes chosen for their offspring, but thats about it. Since dragonflies have extraordinarily good vision, the males rely mostly on their eyesight to find appropriate female partners. A typical pond or lake habitat will support many species of dragonflies and damselflies. To succeed in passing on his DNA, a male dragonfly must be able to distinguish females of his own species from all the other Odonates flying around. He can recognize a conspecific female by observing her flight style, her colors and patterns, and her size. How Dragonflies Mate (and the Wheel Formation) As with many insects, male dragonflies make the first move to initiate sex. When a male spots a female of his own species, he must first subdue her. Hell approach her from behind, usually while they are both in flight, and hold onto her thorax with his legs. He might bite her, too. If he hopes to mate successfully, he must get a firm  grip on her quickly. He pulls his abdomen forward and uses his anal appendages, a pair of cerci, to clasp her by the neck (her prothorax). After he has her tightly by the neck, he extends his body and continues to fly with her, in tandem. This position is known as tandem linkage. Now that hes got a hold of a mate, the male dragonfly prepares for sex. Dragonflies have secondary sex organs, meaning they dont store sperm near the copulatory organ. He must transfer some sperm from a gonopore, on his ninth abdominal segment, to his penis, which is located under his second abdominal segment. After hes charged his seminal vesicle with sperm, hes ready to go. Now for the acrobatics. Somewhat inconveniently, the females genital opening is near her thorax, while the males penis is closer to the tip of his abdominal segments (on the underside of his second segment). She has to bend her abdomen forward, sometimes with coaxing from the male, to bring her genitalia into contact with his penis. This position during copulation is known as a wheel formation because the couple forms a closed circle with their joined bodies; it is unique to the order Odonata. In dragonflies, the sex organs lock together briefly (not so for damselflies). Some dragonflies will mate in flight, while others will retire to a nearby perch to consummate their relationship. Competition Among Male Dragonflies If given the opportunity, a female dragonfly might mate with multiple partners, but the sperm from her final sexual partner will fertilize her eggs, in most cases. Male dragonflies, therefore, have an incentive to make sure their sperm is the last to be deposited in her. A male dragonfly can increase his chances of fatherhood by destroying the sperm of his competitors, and hes well equipped to do so when he mates. Some dragonflies have backward-facing hooks or barbs on their penises, which they can use to scoop out any sperm they find inside their partner before depositing their own. Other dragonflies use their penises to tamp down or move the offending sperm, pushing it aside before he places his own in the ideal location for fertilization. Still, other dragonfly males will dilute any existing sperm they find. In all cases, his goal is to ensure that his sperm supersedes that of any prior partners she has had. Just to provide an added measure of security for his sperm, the male dragonfly will often guard the female until she oviposits her eggs. He tries to prevent her from mating with any other males, so his sperm is assured the last in position that will make him a father. Male damselflies will often continue to grasp their partners with their cerci, refusing to let go until she oviposits. Hell even endure a dunking in the pond if she submerges to place her eggs. Many dragonflies prefer to guard their partners by simply chasing off any approaching males, even engaging in wing-to-wing combat if necessary. Sources Paulson, Dennis. Dragonflies and Damselflies of the West. Princeton University Press, 2009.Resh, Vincent H., and Ring T. Carde, eds. Encyclopedia of Insects, 2nd ed., Academic Press, 2009.

Smokers’ Social Responsibility Supporting Cigarette Ban...

Smokers’ Social Responsibility: Supporting Cigarette Ban in Outdoor Areas Audience: Smokers in the city Genre: An article in local newspaper Results of many researches have proven that concentrations of tobacco smoke in outdoor areas possess the risk to individuals, kids and environment. Even cigarette butts are equally hazardous for environment and many creatures, especially in sea. Therefore, the recently laid ban on smoking in outdoor area in our city is a good move. However, the support of smokers is very much needed to make it successful. I appeal to all smokers to avoid smoking in restricted outdoor areas in ban such as park, beaches, playgrounds, enclosed public places and places of employment. Smoke exhaled by the smoker and†¦show more content†¦People with asthma and bronchial infection problems can face problems due to drifting tobacco smoke and cause other serious health problems in nonsmokers – without any such conditions. These serious health impacts include an elevated risk of heart diseases and lung cancer along with a range of respiratory diseases. Apart from illness, many non-smokers report discomfort in presence of the tobacco contents in air. Smokers shall understand the adverse effects of their habit on people surrounding them, among them are your near and dear ones also. Apart from above mentioned problems, there are many other negative effects for which facts suggest an association with ETS, but scientists are researching further for confirmation. These incorporate cervical cancer, uncontrived abortion, and chronic respiratory symptoms in adults and reduced fertility in female. Relative risk estimates related with few of these disorders and disease are small, but as the diseases are widespread, the overall impact can be fairly large. The collective evidence suggests a relative risk estimate of 1.2-1.7 for heart disease mortality in nonsmokers. For Asthma induction and middle ear infections, the relative risk is 1.62 and 2.25, respectively. A result of meta-analysis for all women states the risk of breast cancer 1.25 [1]. Late st studies also indicate negative impacts of tobacco contents exposure on menstrual cycles. Until now, many citizens are exposed to environmentalShow MoreRelatedChange Essay4238 Words   |  17 Pagesorganisation giving a detailed description of the organisational background and the change event. The paper further goes to list the research questions and review the purpose and scope of the study. The change models and relevant documentation supporting the study are discussed and used to better gain in depth understand of the change situation. It concludes by explaining the study methods used to acquire information about the organization and change management process. 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The Red Carpet of My Life Free Essays

To further the cultural scene and repercussions, the novelist also makes a comparative study by expanding the background of the novel from the Shivalik Hills to Canada. Undoubtedly, human sensibility is alike all around. That is, human beings are not always necessarily rational even in the best circumstances. We will write a custom essay sample on The Red Carpet of My Life or any similar topic only for you Order Now In such a critical situation it is difficult to get solace and comfort. In this novel, it is shown that the hills have many dull men. The reason is explained through the characterization of Kalia and his ironical life since birth. To buy liquor is his need and he has to supplement finances; he wants Gauri to earn more. She is not in a position to earn more through hard work. To fight the situation, he with all his taciturnity arranges to sell his sister Gauri for Income Tax free Rs.20,000. The man who comes forward to buy is a weak man of this area only and spends money on her to supplement the roles of a woman and an ox: Poverty thy hood uncoils often. Kalia would be a talkative man for a while. Later, he was to be dumb—Gauri a forced dumb—he willingly so ever and anon. Gauri’s buyer had constraints beyond control. His poverty-stricken condition could not allow him much to spend. Last week only, an ox of his died. The plough could not move without a couple of oxen. It would—the purchase of Gauri— definitely save him two purchases. The bride too was an item to purchase. She was so young. Always busy with physical work. (38) All this kills the life force in her. She tries to commit suicide but God saves her. One day, after widowhood, she reaches back to her family. Kalia is no more. His wife is remarried to Mahato. Kalia’s daughter is Sonam and Mahato’s son is Ravi. It is really an ironical but actually factual example of the decaying culture. The brother who is supposed to take care of the safety of a sister sells his sister for money. In the modern society, a man has lost his sense to that extent where one cannot reach the core. As far as child atrocities are concerned, they are often neglected or abused in a family or an institutional setting by those known to them. It is less common for a child to be abused by a stranger. Radha, Chhotu, Gauri etc. are made to suffer first by their biological parents, brothers or sisters: â€Å"Kalia sold sister, Gauri and later died of country made liquor. (Agarwal 125) Keeping this in mind, the novelist coins the literary term ‘genderex’ as the word gender depicts the social aspects and distinction; and, sex is a biological and nature given discrimination. The folk scene is dismal but the novelist also suggests a way to bring woman out of this vicious circle. Accordingly, free education and books in library help the poor women and Kalia’s daughter Sonam represents this. Her growth as an educated working woman suggests Kalia’s mother to pronounce that Gauri is ‘The Last Sufferer.’ Meaning thereby that free education by government would help women grow. Education makes a man perfect in his life. It is really a good tool to make a man’s future bright. Dalai Lama once said that â€Å"open your arms free get ready to change with the world but do not let go your values.† (blog.oureducation date 25-8-18 7o clock in the evening.) Characters don’t internalize their feelings and seldom are plagued by mental torment. The characters of the novel are so simple and much far away from the malice and jealousy. They have presence of such expressions in life as love, hatred, greed, fear and jealousy. The life of the rustic people is very difficult. The protagonist of the novel suffers a lot; her path of life is full of thorns though she enjoys heavenly bliss at the end of the story. Literature, based on hilly areas, is related to the illiterate people of that society. In the journey of life, the protagonist gathers courage and strength against the opposite circumstances of life and after that, appears the achievement of the fruit of success which adds heroic dimensions. The themes related to these areas are heart touching. It is, generally, in simple and colloquial language. Sonam and Ravi are good at studies. Education is free, with the attempts of government. Keeping in mind this scene, the novelist prophecies that Gauri is the last sufferer because if an individual is progressive there is much to do and Sonam is getting education to work outside domestic walls to be independent. When the moment of suicidal bid on the part of Gauri passes away: â€Å"A heavy down pour of precious pearls on the cheeks melted the filth in the heart.† (46) Gauri reaches home. In her mother’s house, she talks to Kalia’s wife frankly: ‘I say so because I know the taste of hunger.’ ‘I know the labour of an ox.’ ‘I know the anger of a husband.’ ‘I know the lack of motherhood.’ ‘I know the lack of companionship.’ ‘Without the loss of virginity, I know the loss of womanhood.’ ‘I know the stranger’s status in my husband’s house.’(54) This painful expression of Gauri, stating those facts of her life which marred every iota of joy during these years passed with the husband who is incapacitated in every sense of the word. ‘Don’t you worry about Sonam. She will change her'(55). Gauri did not die. Anyhow, she understands the world around. Gauri knows that untimely death of a young girl may be her destiny. Gauri vehemently expresses that the girl might suffer at the hand of outsiders and her life be curbed: The novelist sets a moral through the growth of Chandrima. She is an orphan brought up by Radha, an orphan, sold thrice and rehabilitated five times. Radha is sheltered by Mrs. Preet Rani in her orphanage which is later on handed over to Radha. How to cite The Red Carpet of My Life, Papers

Microeconomics Additional Cost Charge

Question: Describe about the Microeconomics for Additional Cost Charge. Answer: 1. Business passengers are less sensitive to price. This allows the airlines the potential opportunity to charge additional costs arising from the price-based policy instruments to the passengers (Brons et al., 2002). The business passengers can, therefore, be charged more than the proportional without decreasing the demand. This explains why the estimated elasticity of demand (0.4) for transatlantic air travel in business class is less than that of the economy class at 0.62. This indicates that with a slight change in price for the economy class which is highly sensitive to price, there will be a bigger change in demand hence the higher elasticity for economy class than business class. 2. A slope of a straight-line demand with a constant slope has constantly altering elasticity. The measured elasticity increased as one moves up the demand curve to higher prices and lower quantities (Bass, 2010). The explanation is based on concept of elasticity itself that is percentage change-based (amount of change and starting point of the change). Since the slope is fixed, unit change is identical for individual segment on the curve but the base values are changing. References Bass, F. M. (2010). The relationship between diffusion rates, experience curves, and demand elasticities for consumer durable technological innovations. Journal of Business, S51-S67. Brons, M., Pels, E., Nijkamp, P., Rietveld, P. (2002). Price elasticities of demand for passenger air travel: a meta-analysis. Journal of Air Transport Management, 8(3), 165-175.