INFLUENCE OF ENVIRONMENTAL FACTORS
There are many parasitic relationships in today’s
environment. This is where a parasite will use an organism to its advantage by
getting proper nutrition or living conditions of some sort from their chosen
host. (1) There are many things that could influence how parasites choose their
hosts and gain the proper abilities to do so. One of the major influences is
the environment. Factors caused by the environment can greatly influence the
strengths or weaknesses of a relationship between a parasite and its host. (2) Some
of these environmental factors include, but are not limited to, the temperature
and altering an organism’s habitat. (3)
POSITIVE INFLUENCE
Environmental factors can greatly strengthen the
relationship between a parasite and its host. For example, whenever temperature
increases in the habitat of a host and parasite, hosts can obtain the ability
to have a greater amount of offspring. This being said, warmer temperatures are
expected to yield a stronger presence of parasitic relationships, because that will
increas the amount of susceptible hosts for the parasites. (4) As well as this,
there are some parasites that survive better in the warmer temperatures, thus
making them a bit stronger. For the malaria parasite, Plasmodium falciparum, temperature plays one of the biggest roles
in its development. As well as the proper amount of rainfall, warm climates are
crucial in order for the mosquitoes, the intermediate host of P. falciparum, to survive. This being
said, mosquitoes are less likely to bite in colder temperatures, thus
inhibiting the spread P. falciparum.
(5)
Mosquitoes less likely to bite in cold temperatures (6)
NEGATIVE INFLUENCE
Not only can the environment have a positive influence on
the relationship between the host and the parasite, but also it could affect it
negatively and create a disturbance or stress for the organisms. (3) For
example, humans can alter organisms’ habitat by converting a forest to something
like an amusement park. This changes the environment completely for the
organisms that once occupied that space, and thus creates a stressor among
them. This causes the relationship between any kind of host and parasite to
weaken, which might ultimately lead to the parasite’s life coming to an end. In
this instance, the parasite is more affected by the environmental disturbance
than the host. However, in other cases,
different hosts in a single environment may start dying rapidly thus causing
the parasites to eventually be removed from the population as well. (3) The
malaria virus, P. falciparum, could
also be used as an example to describe how the environment can influence a
parasite negatively. Whereas warmer temperatures aid in strengthening the
relationship between P. falciparum
and its mosquito host, the colder temperatures weaken it. Another species with
similar results is the Daphnia longispina
and the Caullerya mesnili parasite.
An experiment was conducted that resulted in more D. longispina species being infected with C. mesnili in 12°C
rather than at 20°C. (7) This being said, warmer temperatures have an opposite
affect on C. mesnili than how it
affected the malaria parasite.
Daphnia longispina (8)
WHY
DOES IT MATTER?
The
environment can affect parasitic relationships in many different ways. For
example, colder temperatures have a different affect on different types of
organisms. This explains why some species can only survive in certain places
around the world. This also suggests
that the environment has a lot to do with the selection of hosts among
different parasites (9). Environmental
factors can also take a role in the explanation of why some parasitic
relationships are not strong in areas that would be expected. This could occur
in places where an organism’s habitat has been altered.
SOURCES
(1) http://www.cdc.gov/parasites/
(2) http://rspb.royalsocietypublishing.org/content/early/2010/12/21/rspb.2010.2359.full
(3) http://parasitology.msi.ucsb.edu/pubs/Lafferty_Kuris_05_Thomas.pdf
(4) http://www.cidd.psu.edu/research/synopses/parasites-and-climate-change
(5) http://www.nature.com/srep/2013/130218/srep01300/full/srep01300.html
(6) http://www.dailymotion.com/video/x14tju7_mosquitoes-less-likely-to-bite-in-cold- temperatures_news
(7) http://rsbl.royalsocietypublishing.org/content/early/2010/08/06/rsbl.2010.0616.full
I found your post very informative and you presented very good examples regarding how the environment can impact various parasites. I would also like to add the environment of some humans bodies can also fight off certain parasites. For example, humans with one allele for sickle cell disease have a better chance of fighting malaria, due to the their red blood cells not being able to hold hemoglobin properly . This makes it harder for the malaria parasite to survive in this environment.
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