Issues exploration paper
Amphibians – Frogs and preservation
Throughout the 1800s theories of human origin and human evolution began to
flourish and rise throughout the world. Questions such as where do we come from,
became more and more common. As we continue to progress and populate the earth we
have developed the capacity to overcome the other species that inhabit the earth by
demonstrating our superiority. One of the most evident consequences seen through this
expansion of our populace has been the extinction of many amphibious habitats.
We all need to become more aware and do our part to preserve these habitats due
to the amount of benefits they provide. Frog populations have been one of the most
affected amphibious habitats. “Having lost an estimated 170 species in the last 10 years
alone, with another 1,900 in a threatened state, which is one step below the endangered
designation (Pushcendorf 2011)” One perfect example of this mistreatment was found in
a study performed in California.
“A fungal pathogen has been directly connected to the recent extinction and serious
decline of hundreds of amphibian species. The pathogen recognized as Batrachochytrium
dendrobabtidis spread through three lakes, each of which contained populations of the
yellow-legged frog. The disease spread through the populations in a wave-like pattern
until all populations were infected. The prevalence rapidly reached 100% and the
infection intensity on frogs increased in parallel. Frog mass mortality began only when
infection intensity reached a critical threshold and repeatedly led to extinction of
populations. (Vance 2010)”
Chemicals that are used for pesticides are one of the most common causes of this
catastrophe. Atrazine is a very common pesticides, consuming almost 80 billion pounds
of pesticide are used every year. Farmers use this chemical when harvesting sugar, yams,
rice, corn, and for common lawn care. The effects harm embryonic development and
cause frogs to exhibit altered morphology. (Bartell 2013) Atrazine disrupts endocrines
that will ultimately cause male frogs to change into females. Studies have also confirmed
that atrazine can cause cancer in mammals and dramatically alter fish development. This
pesticide can be most commonly found in rainwater, tap water and groundwater.
Overcoming this predicament can be found to be extremely challenging due to the $14.2
million in sales during 2012 a 7% increase from 2011. (Syngenta 2012)
Climate change is the change of weather patterns over time caused by biotic
processes and variations found in weather patterns. Dramatic changes in weather have a
large effect on amphibians for various reasons one being the way their eggs are laid.
Amphibians require a wet climate to lay their eggs, they lack a hard shell and consist of
wet jelly –like sacks. This makes successful reproduction extremely difficult especially
among frogs that are found in high mountainous regions. The University of Pennsylvania
conducted a study to measure the potential harm.
“Harlequin frogs are vibrantly colorful and active genus of frog in Central and South
America. They suffered widespread extinction in the twentieth century – 67% of 110
species – despite attempts at habitat protection. The culprit is apparently a pathogenic
outbreak triggered by climate change. (Wayne 2007)”
The pathogen is known as Chytrid fungus and it grows on moist skin eating away
the epidermis and teeth, before causing the frog to die. Approximately 80% of the
harlequin frog species was eliminated after an unusually warm year. As mountainous
climates become warmer the chytrid fungus continues to expand in elevation range to an
approximate 5348M elevation, chasing certain species of frog to extinction. The fungus
has been detected on 287 species of amphibians and over 36 countries.
A more popular method of frog elimination is found in elementary, Jr. high and
Sr. high schools. Beginning in the 1920’s dead frogs became readily available to schools
for use in educational programs. Frog dissection eventually became a common routine in
numerous high school classes throughout the world. In 1988 it had been determined that
frog dissection occurred in 75-80% of pre-college level courses. (Orlans 1988)
Advancements in technology have provided a lifeline to all of the millions of frogs that
suffer from dissection. New interactive methods have been developed that allow students
to further understand and interact with a variety of dissectible animals. The use of these
methods also allows students the opportunity to understand and value all forms of life.
Now that we have developed a more profound understanding of the many dangers
faced by frogs we can begin to understand why it is so necessary for us to preserve them.
Frogs have been the cause of many breakthroughs in medical science and research. The
largest breakthrough came from the discovery of peptides and antimicrobial agents found
on frog skin. Frogs are very susceptible to disease due to the nature of their habitats.
Fortunately they have developed this antimicrobial agent that secretes through their skin
and allows them kill bacteria that could potentially cause them harm. Scientist are
beginning to analyze the agents found in these secretions and have found over 76
antimicrobial peptides that can be used in modern medicine. “Intensive and systematic
studies on the broad-spectrum antimicrobial peptides found in amphibian skin secretions
are of particular interest in the quest for new antibiotics to treat multiple drug-resistant
bacterial infections. (Xi, 2013)” Researchers from Vanderbilt University conducted the
following experiment that identifies current research using frog secretion to combat
viruses.
“Topical antimicrobicides hold great promise in reducing human immunodeficiency virus
(HIV) transmission. Amphibian skin provides a rich source of broad-spectrum
antimicrobial peptides including some that have antiviral activity. We tested 14 peptides
derived from diverse amphibian species for the capacity to inhibit HIV infection. Three
peptides (caerin 1.1, caerin 1.9, and maculatin 1.1) completely inhibited HIV infection of
T cells within minutes of exposure to virus at concentrations that were not toxic to target
cells. (VanCompernolle 2005)” The university also conducted experiments testing other
viruses such as as murine leukemia.
Unfortunately the decline of frog populations is also frustrating efforts to conduct
experiments and further expand existing research. “The southern gastric brooding frog,
found in Australian rainforest in the 1980s, raised their young in the female’s stomach
using enzymes that preliminary studies showed could be used to treat human ulcers. But
the frogs became extinct. (Zetterström 2010)” Research has also shown that medical
experiments using frogs has led to the development of medicine such as painkillers,
relaxants and even anti-depressants.
Other then for medical purposes frogs also service over 20 different species of
animal. They are prey to snakes, lizards, birds, hedgehogs, coyotes, foxes, birds etc.
Frogs have also been used to eliminate insect infestations especially in areas where
insects are known to carry diseases such as the west nile virus and cholera. Tadpoles have
also been used to purify contaminated bodies of water, as they eat algae.
In conclusion we can come to the determination that frogs are vital to our
ecosystem and necessary for growth as humanity. Although we have learned to dominate
over every species on this earth we must also learn to preserve them, as they play a large
role in our progress. Amphibians lead to benefits that will guide our future in a wide
array of professional fields. None of this research would have been possible without first
creating awareness and then providing the necessary funds to allow the continuous
growth. We must seek opportunities within our own communities to demonstrate our
concern and together create a better life not only for humans but also for every species.
Citations
VanCompernolle SE, Taylor RJ, Oswald-Richter K, Jiang J, Youree BE, Bowie JH, Tyler
MJ, Conlon JM, Wade D, Aiken C, Dermody TS, KewalRamani VN, Rollins-Smith LA,
Unutmaz D. Department of Microbiology and Immunology, Vanderbilt University
School of Medicine Journal of Virology (Impact Factor: 5.08). 10/2005; 79(18):11598606. DOI:10.1128/JVI.79.18.11598-11606.2005
Source: PubMed
Zetterström, R. (2010). Sustaining Life. How Human Health Depends on Biodiversity.
Acta Paediatrica, 99(6), 953-954. doi:10.1111/j.1651-2227.2010.01773.x
Xi, X., Li, R., Jiang, Y., Lin, Y., Wu, Y., Zhou, M., & ... Shaw, C. (2013). Medusins: A
new class of antimicrobial peptides from the skin secretions of phyllomedusine frogs.
Biochimie, 95(6), 1288-1296. doi:10.1016/j.biochi.2013.02.005
Wayne Hsiung and Cass R. Sunstein
University of Pennsylvania Law Review, Vol. 155, No. 6, Symposium: Responses to
Global Warming: The Law, Economics, and Science of Climate Change (Jun., 2007), pp.
1695-1740
Orlans, F. Barbara. “Debating Dissection.” The Science Teacher 55(1988):36-40.
PUSCHENDORF, ROBERT, et al. "Environmental Refuge From Disease-Driven
Amphibian Extinction." Conservation Biology 25.5 (2011): 956-964. Academic Search
Premier. Web. 5 Dec. 2013.
Syngenta 2012 Full Year Results ." 2012 Full Year Results. N.p., n.d. Web. 05 Dec.
2013.
Bartell, S. M., Brain, R. A., Hendley, P., & Nair, S. K. (2013). Modeling the potential
effects of atrazine on aquatic communities in midwestern streams. Environmental
Toxicology & Chemistry, 32(10), 2402-2411. doi:10.1002/etc.2332