Respuesta :
Complete question:
In Australia, both opossums and foxes eat rats. The sizes of the populations have been stable for the last 12 years, but recently the size of the opossum population increased. What will likely happen to the fox population? It will . .
- increase. An increase in the size of any population leads to an increase in the size of all other populations in an ecosystem.
- stay the same. Opossums and foxes do not eat each other, so the number of births and deaths in the fox population will stay the same.
- decrease. The larger opossum population will leave fewer energy storage molecules for all other populations in the ecosystem, so the fox population will reproduce less. This will lead to fewer births than deaths in the fox population.
- decrease. Fewer energy storage molecules will be available to the fox population from the smaller rat population, so the fox population will reproduce less. This will lead to fewer births than deaths in the fox population.
Answer:
Decrease. Fewer energy storage molecules will be available to the fox population from the smaller rat population, so the fox population will reproduce less. This will lead to fewer births than deaths in the fox population.
Explanation:
In the trophic web occurs a process of energy transference through different organisms that places at different levels. Each level feeds on the preceding one and becomes food for the next one. The first link is an autotroph organism or producer. The following links are the consumers: herbivores are primary consumers and feed on producers. Carnivores are secondary consumers and feed on herbivores, and so on. The last links are the decomposers, microorganisms that act on dead animals degrading organic matter.
If any of the links change their population size (increasing it or decreasing it), it affects the superior links and the immediately anterior link.
Also, when two or more species are competing for the same source of food, a change in any of the population sizes will affect the other ones.
In the exposed example, foxes are affected by the increase in the opossum population size, that a direct competitor.
Both species, opossums and foxes, feed on the rats. As long as their population sizes remain stable, no species will be hardly affected by the other. However, when a change occurs, the size of any of the populations is altered, indefectibly affecting the other populations. In this example, the opossum population increased. The more opossums are in the region, the more they will prey on rats. Opossums will become stronger competitors to foxes, whose population remains the same. Rats´ population is also affected because they do not have enough time to reproduce at a higher rate recover. So we have
- opossum reproducing at a higher rate
- opossum population increasing
- opossums strongly competing with foxes
- more opossums feeding on more rats
- rats not being able to reproduce at a necessary rate
- rats decreasing in number
- foxes not having enough food (rats) to feed on
- foxes survival and reproductive rates affected
- foxes death rate increasing
- foxes population decreasing.
As more opossums are feeding on more rats, and fewer rats are available for foxes, the fox population is affected. They do not have enough food to feed on and to survive. And they do not have enough energy to reproduce. So the survival and reproductive rates in the foxes population decrease. And as they do not have enough food, their death rate increases. Eventually, the fox population decreases in size.
