Rodents living in the Chihuahuan Desert can be classified as granivores that eat
ID: 215540 • Letter: R
Question
Rodents living in the Chihuahuan Desert can be classified as granivores that eat seeds or insectivores that eat insects. At the study site of Dr. Brown, there are three species - a large granivore, a small granivore, and a small insectivore. Dr. Brown and her colleagues wanted to know if the large granivore species limited the abundance of the smaller rodent species and if the two rodent species were competing for food The researchers set up plots surrounded by fences. One plot was surrounded by a fence that had holes that allowed both the big and small rodent species to enter and exit (the control plot). The other plot had holes that only allowed the small species to enter and exit (the excluded plot). At the start of the experiment, all large granivore rodents were removed from both plots. The numbers of the large granivore species of rodent in the plots over time was measured as a control to ensure that the small holes excluded the large rodent species. In the control plots, typical numbers of the large granivore species were found after removal (that is, the removed large rodents were able to return to the control plots). The researchers found none of the large granivore species after removal in the excluded plots (that is, the large rodents were not able to get through the fence to return to the excluded plots) Dr. Brown's hypothesis is that the large granivore species limits the abundance of the small species of granivores because they can outcompete the small species for food. What result on the numbers of small granivore species of rodent in the two plots would support this hypothesis A. The number of small granivore rodents in the control plot would be higher than the number B. The number of small granivore rodents in the control plot would be lower than the number of C. The number of small granivore rodents in the control plot would be equal to the number of D. The number of small granivore rodents in the control plot would start higher, then decrease of the small granivore rodents in the excluded plot the small granivore rodents in the excluded plot. the small granivore rodents in the excluded plot. to the same number of the small granivore rodents in the excluded plot. An alternative hypothesis is that the large granivore species can simply outcompete any small species of rodent, regardless of diet. What result on the numbers of small insectivore species of rodent in the two plots would allow you to reject this hypothesis A. The number of small insectivore rodents in the control plot would be higher than the number B. The number of small insectivore rodents in the control plot would be lower than the number C. The number of small insectivore rodents in the control plot would be equal to the number of D. The number of small insectivore rodents in the control plot would be start higher, then of the small insectivore rodents in the excluded plot. of the small insectivore rodents in the excluded plot. the small insectivore rodents in the excluded plot. decrease to the same number of the small insectivore rodents in the excluded plot.Explanation / Answer
Interaction between population may be:
Intraspecific- interaction between individuals in the population of same species or strains.
Interspecific- interaction between individuals in the population of different species or strains.
These interactions between similar individuals, may vary under different factors, like environmental conditions, ecological niche, or limiting resources.
When individuals interact in such a way, that it limits the existence of the other, creates an adverse effect, or is even detrimental to certain individuals in a population, such interactions are described as competition.
Usually, competition occurs under the condition of limiting resources, like sharing if ecological niche, food, water, mating conditions, size and health of the individual, etc. Competition may be again, interspecific, or intraspecific.
In this case, two conditions of limiting factors could either be:
a) Size of the individual species of rodent- as large (large granivores) and small (small granivores and small insectivores).
b) Feeding or eating habit of the individual species of rodent- as granivorous or insectivorous.
1. According to the hypothesis, where food is considered as limiting factor, the large granivores and small granivores will compete for food (as both are granivorous).
Thus, considering the condition, that the large granivores and small granivores are competing for food as limiting factor; due to advantage in size, the large granivores can outcompete the small granivores.
Hence,
In control plot, where the large and small granivore can interact, the population size will decrease.
In excluded plot, where the large and small granivore cannot interact, the population size will not be affected.
But here, initially the large graivores are excluded. Thus, the population of control plot would start higher, and then decrease to reach an equilibrium point.
Thus, correct option is D.
2. Considering alternate hypothesis, where size is acting as limiting factor, the larger rodents should compete with both granivorous and insectivorous rodents of smaller size (irrespective of feeding habit). The population size of smaller rodents (both as granivorous or insectivorous should decrease). Thus, if there is no effect or very less impact on population of insectivorous smaller rodents, the alternative hypothesis may be rejected.
Thus, correct option is C.
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