BIOB50H3 Chapter Notes - Chapter L#2: Schistosomiasis, Global Warming, Cellular Respiration
BIOB50 TEXTBOOK NOTES
CHAPTER 1: Pg 2-20 (LECTURE #2 READINGS)
- Humans have: transformed nearly half of Earth’s land surface, introduced new species
to areas, altered atmosphere of Earth (leading to climate change), ocean have dead
zones (low oxygen concentrations), decline in fish, coral reefs etc.
-Natural systems are driven by how org. interact w/ eachother and w/ their physical
env.
-Ecology: scientific study of how org. affect and are affected by other org. and their env.
Connections in Nature
- Phrase used to refer to events in
natural world being linked to
eachother caused by org.
interactions w/ eachother and
their env.
- All org. connected through
features of their env. eg. All
need food, space, other resources
etc.
Thus 2 species that don’t
interact directly, stil influence
eachother
Parasites and Amphibians
- Stephen Ruth discovered pacific
tree-frogs and long-toed
salamanders w/ extra limbs, missing limbs, other deformities all contained parasite
called Ribeiroia ondatrae (flatworm)
Tested hypothesis of flatworm causing development issues by using glass beads on
developing limb areas (mimics the worms effect) had limited limb development
-Johnson found 13 Pacific tree frogs of which 4 had deformities, while 15-45% of
tadpoles had some type of deformities
Proposed possible pollutants like pesticides were to blame none were found in the
ponds
Found that the ponds where they found the deformed frogs had snail Helisoma
tenuis snail is first of 2 intermediate hosts required for the parasite (requires
frog/fish as 2nd host for its life cycle)
oFound parasitic cysts in all the frogs w/ deformed limbs
Performed a controlled experiment tested experimental group with the control
group
oIn containers with parasite, very low survival rate (60% killed) + born with
deformities
oIn container w/o parasite 88% survival, no deformities
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-Kiesecker did study to see joint effects of pesticides and parasites on frog
development
Went to 6 ponds, 3 not close to farm,
3close to farm fields (and contained
pesticides)
In each 6 ponds, placed wood frog
tadpoles in a cage which allowed in water,
but prevented frogs from escaping
Placed 6 cages in each pond 3 had cages
w/ mesh to allow parasites to pass
through, 3 had mesh too small for
parasites i.e 3 tadpoles in each pond
were exposed to parasites, 3 weren’t
oFound: no deformities in frogs w/
cages too small for parasite
(regardless of pond), some
deformities in cages w/ mesh to
allow parasite (dissections show
every frog w/ deformity had
parasite)
oFOUND: greatest # of deformities
in cages which were in ponds w/ pesticides
oConcluded: (1) exposure to parasite was necessary for deformities to occur,
(2) when frogs were exposed to parasite, deformities were more common
in ponds w/ detectable levels of pesticides
Hypothesized: pesticides may reduce ability of frogs to counteract
infection by parasites
In a later experiment (in which he exposed all wood frogs to
parasite, but only some to pesticides) found that pesticides
suppressed the frog immune system (had fewer WBCs)
- Thus: deformities in amphibians are increased possibly b/c increase
of pesticides = decreased ability of amphibians to fight parasite
attacks
- Other env. Changes could possibly be: addition of nutrients to
natural or artificial ponds (can lead to increase in parasitic
infections) more nutrients into crops = more nutrients wash off
fertilizer into pond after rain = more algae = more snails = more hosts
for parasite = greater chance of infection b/c more parasites
- Events are linked eg. Damming of rivers in Africa = good habitats
for snails w/trematode parasites cause schistosomiasis can kill
people
- Many outbreaks of diseases can possibly be linked to human action on the env. (eg.
West Nile Virus thought to have come to North America through people, in 1999)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Humans have: transformed nearly half of earth"s land surface, introduced new species to areas, altered atmosphere of earth (leading to climate change), ocean have dead zones (low oxygen concentrations), decline in fish, coral reefs etc. Natural systems are driven by how org. interact w/ eachother and w/ their physical env. Ecology: scientific study of how org. affect and are affected by other org. and their env. Phrase used to refer to events in natural world being linked to eachother caused by org. interactions w/ eachother and their env. All org. connected through features of their env. Eg. all need food, space, other resources etc. Thus 2 species that don"t interact directly, stil influence eachother. Stephen ruth discovered pacific tree-frogs and long-toed salamanders w/ extra limbs, missing limbs, other deformities all contained parasite called. Tested hypothesis of flatworm causing development issues by using glass beads on. Ribeiroia ondatrae (flatworm) developing limb areas (mimics the worms effect) had limited limb development.
