The Tasmanian devil (Sarcophilus harrisii) is a species of mammal whose only wild population is native to the isolated island of
Tasmania, off the coast of Australia. Tasmanian devils have a very low level of genetic diversity across the entire species. Researchers hypothesize this lack of diversity is the result of several genetic bottlenecks in the species’ history. In 1996 a new disease called devil facial tumor disease (DFTDDFTD) appeared in the wild Tasmanian devil population. DFTDDFTD can spread from one animal to another and causes the death of most affected animals. The impact of DFTDDFTD on the Tasmanian devil population has resulted in a decrease in the total population of more than 85% over the last two decades. (a) Describe the process that maintained a stable Tasmanian devil population size before the appearance of DFTDDFTD in 1996. (b) Explain how the huge reduction of the Tasmanian devil population since 1996 affects the susceptibility of the current population to new diseases in comparison with the susceptibility of the population before 1996. (c) Tasmanian devils are top predators and are considered a keystone species in their community. Predict the effect of the rapid reduction of the Tasmanian devil population on the rest of the community. (d) Justify the prediction of Part c
1 answer:
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How does the altered circulation in Mr. G correlate with his symptoms? Drag and drop the appropriate labels into the correct sequence to clarify how this defect could lead to Mr. G's other issues. Complete the boxes in order, starting with 1, then 2, etc.
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Answer:
- When the left ventricle contracts, a portion of the blood flows through the mitral valve into the left atrium. Turbulent flow within the valve results in a systolic murmur, causing the atrium to become overfilled and dilated.
- Some blood returning through the mitral valve means less blood is ejected into the aorta, leading to an ejection fraction of just 43%.
- The reduced flow into the aorta results in lower SBP. The baroreceptor reflex triggers an increase in heart rate; the left ventricle's wall, under stress, thickens.
- Due to being partly filled with blood from the ventricle, the left atrium can receive less blood from the lungs, causing the lungs to become fluid-overloaded, leading to difficulties in breathing.
Explanation:
A murmur arises from abnormal heart blood flow. It produces unusual sounds heard between heartbeats. A systolic murmur happens when heart muscles contract, within the intervals defined by S1 and S2.
From the information presented, it appears Mr. G is suffering from mitral regurgitation. This condition occurs when the mitral valve fails to close tightly, causing blood to flow back from the left ventricle into the left atrium.
