The article reviewed in this summary is
Hayes, T.B., Khoury, V., Narayan, A., Nazir, M., Park, A., Brown, T., Adame, L., Chan, E., Buchholz, D., Stueve, T., and Gallipeau, S. 2010. Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis). Proceedings of the National Academy of Sciences 107: 4612-4617. The authors have assigned key words described throughout this article including amphibian decline, endocrine disruption, pesticide and sex reversal. The larger or global context for the research conducted in this article is that the pesticide Atrazine is widely utilized across the entire world, contaminating water sources by mobilizing through rainfall, disrupting habitats and impacting
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Spermatogenesis data was collected from five random testicular tubules as well as the largest tubule. DNA for sex determination was obtained from the prepared toe tips of the amphibians and aromatase samples were collected from the RNA removed from the gonads of atrazine induced females. The authors collected data on mating choice behavior from single and paired frogs of both male groups to ZW stock females placed in a pool together. Testosterone levels were obtained from the same paired and single males by taking centrifuged blood samples and extracting the plasma testosterone. Fertility data was collected by pairing controlled and atrazine exposed males with ZW stock females and gathering eggs and embryos from these matings. The data collected spans from hatching of the larvae until about two to three years after metamorphosis. For the morphometric measurements, statistical analyses were performed. The dilator larynges were examined by the proportion extended beyond the thiohyral in order to determine the significance of the length of the extension. The presence or absence of observable nuptial pads was analyzed, to determine it as a sex characteristic of males. Breeding glands were evaluated by considering the maximum area of the largest gland which was then compared to the areas of other glands to observe the size differences between the control and atrazine treated males. Stages of spermatogenesis for the testis and tubules with and
Rain washes the pesticides that are used in our Australians households and then become run-off in drains and sewers. They then make their way into nearby water bodies, wether that be creeks, rivers or even oceans and settle within the soil by sticking to small particles, including tiny living organisms like phytoplankton (M. Barwick, 2003, pp. 471-502). Small fish consume these tiny organisms, which may then be eaten by a larger organism and this continues until the top order consumer is reached. The concentration that first began in the phytoplankton and has multiplied sufficiently as it moves along the food chain. The amount of the pesticide has reached a highly toxic level in the top order predator, whether that is birds or even humans. As a result of the biomagnification of pesticides and other chemical the marine environment and the organisms that live within it are heavily affected. The build up of heavy metals, for example, it interferes with the formation of red blood cells, creates liver and kidney implications and forms reproductive defects in many organisms. This hinders an organism’s ability to survive and reproduce and can create a decline in species
The alligator is one of the largest living reptiles today. In North America, they inhabit freshwater swamps or wetlands in the south, from Texas to North Carolina. Distinguishing features include the fourth mandibular tooth, the long, broad snout, and the thick, scaly skin. Like some other reptiles, alligators have temperature-dependent sex determination, which is a non-genetic way of determining the sex ratio of offspring produced. Unlike other reptiles, alligators exhibit parental care; they nest-guard, and even offer evidence of maternal care for juveniles after hatching. Through the reviewing of multiple experiments conducted on Alligator mississippiensis, evidence is provided for the temperature-dependent mode of sexing and maternal
In insect species with indirect sperm transfer, sperm is packed in a spermatophore that is either externally attached to the female 's genital opening or introduced into her bursa copulatrix. Sperm transfer is not immediate in these species, and consequently mate guarding has been suggested to function as a mechanism of guarding sperm until it is released from the spermatophore into the female (i.e. spermatophore guarding). Spermatophore guarding is relatively common in insect species with external spermatophores (e.g. Orthoptera; Alcock 1994; Simmons 2001), but supposedly absent in species with internal spermatophores and rapid sperm release (Simmons 2001). This study focuses on two hypothesis associated with mate guarding a tactic of many species that adjust their reproductive behaviour according to the apparent risk of sperm competition. The phenomenon of mate guard to consider sperm competition levels and evolution of internal spermatophore guard is wide spread in insects and other animals. We analyse two hypothesis one the rival exclusion followed by the next spermatophore renewal hypothesis. Results showed that as rival was introduced to the arena of mating of the distinctive original male (guard) in many cases showed a strong aggressive behaviour regardless of whether successively avert the rival. In the second hypothesis certainly majority of the incidents showed an attempt of
This analysis of case studies from Los Alamos National Laboratory, and the case study to predict the effects of pesticides on aquatic systems and the waterfowl that uses them. Comparing the two processes of these case studies, along with analysis of the assessments. Describing the case study on the effects of pesticides in aquatic ecosystem, the risk assessment correlated to observed field studies and evaluate the importance of this type of correlation in general for all risk assessment efforts. Breaking down the ecological and social
Many sources say that the initial spread of this invasive species began at the end of the 1800's when bullfrogs were shipped to California to fill hungry loggers appetite for frog legs. The frogs competed with the other native species with the supply of natural resources while also consuming and exploiting the native amphibian species as well. Worldwide Rana catesbeiana has driven over one-hundred native species of frogs to extinction (Save The Frogs! et al. 2013). This is a huge impact on amphibian wildlife worldwide because there are about 4,800 species of frogs. Over the past hundred years the bullfrog has wiped out over 2% of the world's species of frogs. Studies have shown one of the reasons bullfrogs will cripple Arizonian ecosystems and the native amphibian species directly is because a female bullfrog’s physiology
When fresh G.semen homogenate (“FH” treatments) was used we also observed the slight increase of daphnids body length after 72 h exposure (Fig. 5), but it was not statistically significant (P=0.108 – 0.231, Mann-Whitney U
The prediction that the percentage of male gametophytes would increase as the population density of the gametophytes increased, and the prediction that the percentage of male gametophytes would decrease as the population density of the gametophytes increased were not supported by our results. When the population density was low, the percentage of male gametophytes was relatively low because there would not be enough eggs to fertilize the sperm produced from both the hermaphrodite,and the sperm produced by the male gametophyte. When the population density was high, the percentage of male gametophytes was higher but still less than fifty percent because of the same reasons.The data from our results did support our
There are many environmental culprits that are causing species of amphibians to decline in numbers. Consequently, there are an alarming number of amphibians across the U.S. with deformities such as missing limbs or extra limbs due to environmental causes. Environmental scientists say that the widespread occurrence of amphibians with deformities might be due to water pollution or chemical pollutants in the water. There are other factors that might have caused these frogs to have missing or extra limbs such as parasites, ozone depletion, and weather patterns. However, Amphibians are not the only species that have declined in population. According to an article written by Beth Baker poor water quality is to blame for the decrease in population of sea grass, coral, and fish along with many other misfortunes.
16. Samuel F. Atkinson, William T. Waller, Kenneth L. Dickson, Sirichai Sanmanee, and Maria C. Moreno, “Atrazine Monitoring and Modeling in the Lake Lavon Watershed,” Denton, TX. UNT Digital Library, http://digital.library.unt.edu/ark:/67531/metadc29479/.
The main idea of Road salt can change sex ratios in frog populations was that road salt put down on roads to melt snow, can impact the sex ratios of frogs. The researchers found that the proportions of female in tadpoles were reduced down 10 percent when exposed to road salts. This suggest that road salt may have a masculinizing effect of frogs. For the experiment researchers used a 500 litter tank containing various levels of road salt to leaf litters from maple and oak trees. The scientist observed the sex ratio for the oak leaf litter without salt was female-biased 63 percent. But, when the salt was added the female portion of frogs decrease by 10 percent. The scientist also noticed that the oak leaf litter female tadpoles were larger
As the frog starts to sexually mature it goes through a process called metamorphosis. The frogs body changes, it’s tail gets shorter and the frog grows four limbs Now it can swim and hop, it’s diet also charges were frogs can eat insects as well as other frog and fish depending on
In order to run the statistical tests for this experiment, a larger bullfrog population was acquired by pulling data from an experiment identical in design from the previous year. Through this experiment it was revealed that there was not a significant difference between treatments over time in both tail width and tail length. This is contradictory to what was expected. It was hypothesized that both the low and high thyroxine groups would metamorphose quicker than that of the control and that the high thyroxine group would metamorphose faster than that of the low thyroxine group. Thyroid hormone is important in the metamorphosis in frogs and allows for them to adapt to terrestrial life from aquatic life by shortening the tail and producing
Andrea Smith was taking notes for her biology exam. Her professor has told her that the exam would cover, in part,
Fry and Toone (1986) found when they inject fertilised seabird eggs with DDT and its metabolites. The male chicks produced have varying degrees of intersexuality depending on dosage, reproductive system with both male and female structures. The female chicks had a partial to full developed right oviducts, instead of just left functional structures. In the area where the eggs were collected, there was multiple female-female pairing and low hatchability of eggs. Males exposed as embryos to estrogenic pesticides showed decreased to no sexual behaviour. (Fry and Toone, 1981) Louis Guillette noticed that male alligators from Lake Apopka in Florida have vestigial penis, follicle-like testis and elevated estrogens/testosterone ratios and the female hatching’s ovaries were producing multiple egg follicles and eggs with several nuclei (Luoma, 1995, Guillette et al., 1995) The females also had above normal estrogens levels. When he and his colleagues did a similar injection study with DDT and DDE, they produced results similar to those found in the field. The reduction in penis length and the abnormal gonads made the hatchlings reproductively incapable. Both the bird and alligator studies were prompted by the contamination of large water bodies by organochlorins and the low breeding success of the animals living and feeding in these areas.
Frogs, toads, caecilians, and salamanders are the members of the class Amphibian (amphi- meaning “on both sides” and bios- meaning “life”). These members always require water for reproduction. Most Amphibians undergo metamorphosis, which is a usually degenerative pathological change in the structure of a particular body tissue. And, in the case of Amphibians, it is the changing of a tadpole into