The sex of a male or female is mostly determined by sex chromosomes which results from set of genes. In the recent time, it can be said that environment partly contributes to sex determination. They are so many environmental factors that may affect this production like humidity, cell types, temperature, food, location of the birth and timely of the sexual intercourse but this essay focuses on effect of temperature alongside other factors .
Most reptiles show temperature dependent sex determination in which low temperature within the range of 20-27 degree Celsius producing females and producing males at higher temperature within the range of 30 and above degree Celsius .Temperature in between these two ranges stated above gives varying ratios of males and females. Usually, the temperature is between 28-31 degree is usually termed the threshold. The reason for this variation for this variation is hormonal. Males has higher amount of testosterone and it is their primary sex hormone.. The level of aromatase is necessary for the development of ovaries than the presence or the absence. Aromatase is competitive inhibitor which competes with 5- alpha reductase for androgen substrate in the brain .Aromatase activity in the brain shows increase in the selection of gonads in both sexes. Due to the effect of aromatase (it converts testosterone to estradiol which is form of estrogen) which works at a very low temperature more females are produced in the. If by any chance males are needed in the population, the enzymes could be blocked by raising the temperature.Enzyme is catalyst that speeds up the rate of chemical reaction by lowering the activation energy. Enzyme can be denatured by high temperature and high ph .Most males can also be produc...
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...fact that it need to long term data, correlations and researches. More information is needed on how temperature sex determination works under natural conditions to know its full ecological implication.
Works Cited
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Sturtevant, H. The Himalayan rabbit case, with some considerations on multiple allelomorphs. American Naturalist 47, 234–238 (1913).
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Metabolic rate is directly linked to the core temperature in an animal. An ectotherm, or cold blooded animal, warms its body mainly by absorbing heat from its surroundings. The amount of heat it derives from its metabolism is negligible. In contrast, endotherms derive most or all of its body heat from its own metabolism (Campbells,p899). Because ectotherms do not produce their own heat, they cannot actively ensure their ideal temperature for an ideal metabolic rate (aquacult.htp).
To begin with, gender must be examined at the basic level of science in regard to physical and biological development of humans. We all understand the physical differences between the male and female gender, but how is our sex actually determined. After conception,
The courting ritual begins with the males circling females in an offshore mating ground and then the males approach and bite a female’s neck and if she accepts, they mate; if she does not accept, she swims to the bottom of the mating grounds (Deurmit L 2007). Males have long claws to use during mating because other males try to remove the mating male in order to mate with the female (Deurmit L 2007). Caretta caretta are polygynandrous and breed seasonally in the early summer (Deurmit L 2007). With mating, the females have the ability to store sperm throughout the reproductive season (Sakaoka K et al.). This characteristic developed with “changes in the sperm storage tubules (SSTs) in the oviduct” and allows the females to reproduce more (Sakaoka K et al.). This storage helps to combat climate change because Caretta caretta, as a species, only breed during certain temperatures (Sakaoka K et al.). Female loggerhead turtles have developed sperm storage abilities within mating to combat climate
...to 300 individuals, the newborn seahorses are independent of parental care and the male is free to fertilize and accept more eggs(Lourie 11). The offspring bearing roles displayed by Hippocampus spp. is an extreme shift in relation to many other species of kingdom Animalia, of which the bearing of young is predominantly carried out by females. According to Foster, growth rates throughout the life cycle and the duration of the life cycle of seahorses in the wild varies between species and cannot be determined due to insufficient research data(foster 22). Once sexual maturity is reached, often determined by the presence of a brood pouch in males, adults are able to reproduce. During reproduction, the overwhelming majority of Hippocampus species display monogamous behaviors, usually mating with the same partner for the duration of the mating cycle(lourie 10-11).
"Persistent female choice for a particular male trait values should erode genitive variance in male traits and thereby remove the benefits of choice, yet choice persists” (Miller, Christine and Allen Moore). This phenomenon is know as the Lek Paradox and has puzzled scientists for many years. Throughout all species there has been abundant evidence showing continuous female choice of male traits, yet there is still no definite answer as to what allows for genetic variance to be maintained, and why a specific trait never becomes fixed. Many hypotheses have been theorized and researched, all providing some explanation as to how this variance in species is maintained, from traits signaling resistance to parasites, according to Hamilton and Zuk, to the hypothesis of mutational and environmental affects. Condition-dependence can also provide information as to how the lek paradox is able to exist; this hypothesis will be looked at in this paper.
Nicholson KE, Harmon LJ, Losos JB. Evolution of Anolis Lizard Dewlap Diversity. PLOS ONE. 2007
For example, one can begin to determine the sex of the monarch butterfly in the larvae stage, but can only be done by dissection. The male will have a testis in the sixth abdominal segment, dorsal to the gut. The next stage of life is the Pupae. To determine the sex in this stage you need to have great vision or a microscope. The male butterfly has a cremaster which is a structure from which the pupa hangs, has a series of rings called abdominal sternites. Within the first ring, there are several paired black dots next to the cremaster. To determine that it is a female, the rings adjacent to the ninth sternite will have a line dissecting it which is centered between the pair of dots. Now we enter the adult stage of the Monarch butterfly. The male Monarch butterfly is somewhat larger than the female monarch butterfly. To designate if it is a male it will have a black spot on each of its hind wing. This is the most noticeable way to tell it is a male. In the female Monarch butterflies, they do not have spots on their hind wings they have thicker wing veins which make them darker in color than the male butterflies. If you happen to come across Monarch butterflies with their wings closed we are still able to determine the sex. The males’ dark spot should be able to be seen as it will bleed through the outside
Sexual dimorphism can be defined as “morphological differences or varied appearances between males and females within the same species,” stated from Webster’s Dictionary. Anthropologists and primatologists study sexual dimorphism for various reasons depending upon, what information is trying to be uncovered. For example, a forensic anthropologist might use sexual dimorphism to try to nail down traits that will allow easier identification of a sex within skeletal and dental remains (Plavcan, 2001). Alternatively, a primate biologist may focus on understanding the causes of sexual dimorphism in primates, and how these relate to the variation in behaviors and ecological structure (Plavcan, 2001).
Smith, D. G., & Schenk, M. P. (n.d.). A Dissection Guide & Atlas to the Mink. Google Books. Retrieved May 27, 2014, from http://books.google.com/books?id=kifAAgAAQBAJ&pg=PA83&lpg=PA83&dq=male+mink+reproductive+system&source=bl&ots=6Q8L-rNG76&sig=L2TpamuuykxepCG7uaLJdmyTeuM&hl=en&sa=X&ei=aa-DU8XFA8OhqAa2yIKYAw&ved=0CF0Q6AEwCA#v=onepage&q=male%20mink%20reproductive%20system&f
The traditional explication for the maintenance of sex was that the process of meiosis and fertilization engender genetic variation on which natural cull can act.
Even though there are so many differences between reptile species, there are a few things they all have in common. All reptiles are coldblooded, which is not quite right because there blood isn't cold. Coldblooded or poikilothermic actually means that the animals temperature must be regulated by external factors, that is why lizards are always sun bathing to get warm or in holes to cool off.
Gender is determined by the sex chromosomes, XX produces a female, and XY produces a male. Males are produced by the action of the SRY gene on the Y chromosome, which contains the code necessary to cause the indifferent gonads to develop as testes (1). In turn the testes secrete two kinds of hormones, the anti-Mullerian hormone and testosterone, which instruct the body to develop in a masculine fashion (1). The presence of androgens during the development of the embryo results in a male while their absence results by default in a female. Hence the dictum "Nature's impulse is to create a female" (1). The genetic sex (whether the individual is XX or XY) determines the gonadal sex (whether there are ovaries or testis), which through hormonal secretions determines the phenotypic sex. Sexual differentiation is not drive...
To conclude, the foremost important details of this section is that females amongst organisms are not as innocent as we assumed
Holcomb, D. 2005. "Pseudoryx nghetinhensis" (On-line), Animal Diversity Web. Accessed March 14, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Pseudoryx_nghetinhensis/
When looking at the biological make up of male and females, there are both similar physical characteristics