Question

In Data and Graphing 7, you saw how population growth can be limited by both predation and carrying capacity. Imagine that an invasive species of snail arrives on an island. On this island, it has no natural predators. The snail feeds on an uncommon plant, which grows in only a few places on the island.

1. Will the snail experience exponential or logistic growth in the short term?

2. Once the snail has reached all patches of suitable habitat on the island, will it experience logistic or exponential growth in the long term?

Explain your answers.

Answer 1

Answer 1:

Initially, there would be a very number of snails, and more habitat patches where they can feed on the uncommon plant. Also, they have no predators on the island. This means food will be abundant and no predatory stress on snail population. Thus, there would be neither intraspecific (within the snails) or interspecific (snail and other species) competition and snails would grow exponentially.

Snails will grow exponentially in the short term because of abundant food and lack of any predator.

Answer 2:

In the long run, as the population of snails will rise, fewer and fewer habitable patches with the uncommon plant would be left for occupation. This means, intraspecific competition will arise in the population for food and population would grow logistically.

Snails will experience logistic growth in the long run because once all patches gets occupied food (uncommon plant) will become limited and there will be intraspecific competition among snails.