Whether using artificial insemination or nature’s way, rhino breeders are most successful when they can time sperm transfer to coincide with ovulation The surest way to achieve this synchrony is to induce the female to ovulate when a male rhino or sperm sample is ready. As you have learned, ovulation in mammals is stimulated by a surge of LH and FSH. which in turn is simulated by a surge in GnRH. Ovulation in rhino cows can be induced by injecting the females with a synthetic version of GnRH.
The next step depends on how the cow will be fertilized. For normal mating, the biologists wait until the female shows signs of mating interest. The male and female are then housed together and watched carefully for signs of mating or aggression. For artificial insemination, the biologists use ultrasound to check for the presence of ripe follicles Semen collected from a bull rhino is then inserted into the cow’s uterus. For IVF. the biologists suck ripe eggs out of the cow's ovary. again using ultrasound to guide their efforts, mix the eggs with sperm, and implant the resulting embryos into the cow s uterus.
These procedures have all proven successful. White, black, Indian, and Sumatran rhinos have been successfully bred using one or more of these techniques. With highly endangered species like the Sumatran. Javan, and black rhinos, preserving genetic diversity is extremely mportant. which means that every male and female should be given the chance to pass on their genes by reproducing with rhinos around the world. Artificial insemination using frozen sperm is much safer and less expensive than shipping rhinos between zoos. Artificial insemination can even help to preserve the genes of deceased bull rhinos. Tashi. the Indian rhino cow at the Buffalo Zoo. was artificially inseminated with sperm from Jimmy, a rhino bull who died at the Cincinnati Zoo about 10 years earlier. Jimmy's sperm had been stored all that time, frozen in liquid nitrogen. The Buffalo Zoo named the calf Monica, after Dr. Monica Stoops of the Cincinnati Zoo. who performed the artificial insemination (see the chapter opener photo).
Similar techniques have also been used with other endangered species For example, at the Smithsonian National Zoo in Washington. D.C.. black-footed ferrets were born whose fathers had died almost a decade earlier. In addition to the Cincinnati Zoo. several other facilities including the Audubon Nature Institute and the San Diego Zoo. maintain Frozen Zoos—liquid nitrogen storage tanks containing frozen sperm, tissue samples, and even embryos tom endangered species.
By rhino standards, southern white rhinos are abundant—there are about 20,000 of them. In contrast, there are fewer than 50 Javan rhinos and 100 Sumatran rhinos in the world. How might white rhinos be used to increase reproduction of Javan and Sumatran rhinos? Describe advantages and obstacles to you proposals.
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BIOLOGY: LIFE ON EARTH ACCESS CODE W/E
- Ovulation in mammals, whether it is induced or spontaneous,occurs in response to a surge of luteinizing hormone (LH).Compare and contrast the ways the LH surge is generated ininduced and spontaneous ovulators.arrow_forwardBirth control pills are oral contraceptives taken by women to prevent pregnancies. The most effective forms of birth control pills contain estrogen and a small amount of progestin (a synthetic hormone that mimics the effects of progesterone). Although the most effective forms of oral contraceptive for women contain estrogen and progestin, some birth control pills contain a small dose of progestin only. This is because there are many risks and side effects associated with estrogen.Which of the following statements is NOT a reason for using a progestin-only oral contraceptive? Select one: a. Progesterone suppresses the maturation of follicles, thereby preventing ovulation of a mature ovum. b. Progesterone maintains the corpus luteum as corpus luteum releases a large amount of progesterone and some estrogen. c. Progestin-only oral contraceptives prevent the production of FSH and LH in the anterior pituitary. d. Progesterone suppresses the production of GnRH in the hypothalamus.arrow_forwardFishes and some species of amphibians like frogs fertilize their eggs outside of their body. Which of the following statements is TRUE about external fertilization? * A small number of gametes need to be produced by the male and female to ensure reproductive success It produces a small number of offspring compared to internal fertilization A body of water is not required no answer Chances of fertilization are diminished by environmental hazards and Predatorsarrow_forward
- Female athletes who train intensively often stop menstruating. The important factor appears to be the reduction of body fat below a certain level. Give a possible evolutionary explanation for a relationship between body fat in females and reproductive cycles.arrow_forwardMate guarding is an evolved response to sperm competition. Chimpanzee (Pan troglodytes) females regularly mate with several males in the same estrous cycle, whereas gorilla (Gorilla gorilla) females almost never do, since they typically live in bands, each controlled by a single, powerful male. How large (as a proportion of body size) should the testes of chimpanzee males be relative to gorilla testes (Harcourt et al. 1981)? If the testes of men are more similar to those of chimpanzees, what would this tell us about the intensity of sperm competition during our evolutionary past? If, on the other hand, human testes resemble those of gorillas, what conclusion is justified? Please don't write from any online source.arrow_forwardAlthough the most effective form of an oral contraceptive for woman contain estrogen and progestin, some birth control pills contain a small dose of progestin-only. This is because there are many risks and side effects. Which of the following statements is NOT a reason for using a progestin-only oral contraceptive? Select one: A. progesterone maintains the corpus luteum as corpus luteum release a large amount of progesterone and estrogen. B. progesterone suppresses the maturation of follicles, thereby preventing ovulation of a mature ovum. C. progestin-only oral contraceptives prevent the production of FSH and LH in the anterior pituitary. D. progesterone suppresses the production of GnRH in the hypothalamus.arrow_forward
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- Why does the estrogen released at the follicular phase inhibit FSH levels by a negative feedback mechanism? A high level of FSH will cause ovulation. A high level of FSH will cause menstruation. To ensure that the endometrium is ready to receive an embryo. To prevent multiple follicles from maturing at the same time.arrow_forwardA friend of yours wants to better understand the difference between estrous and menses in mammals. Which answer below would provide a good way of explaining the main difference? O only menstrual cycles are affected by seasonal changes throughout the year O copulation normally occurs across the estrous cycle, whereas in menstrual cycles copulation only occurs during the period surrounding ovulation O the endometrium shed by the uterus during the estrous cycle is reabsorbed with no extensive fluid flow out of the body, whereas the shed endometrium of menstrual cycles is excreted from the body O behavioral changes during estrous cycles are much less apparent than those of menstrual cycles MacBook Proarrow_forwardFigure 18.17 Which of the following statements about hormone regulation of the female reproductive cycle is false? a. LH and FSH are produced in the pituitary, and estrogen and progesterone are produced in the ovaries. b. Estradiol and progesterone secreted from the corpus luteum cause the endometrium to thicken. c. Both progesterone and estrogen are produced by the follicles. d. Secretion of GnRH by the hypothalamus is inhibited by low levels of estrogen but stimulated by high levels of estrogen.arrow_forward
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