Question

Ecology Homework Questions help! Thank you in advance!

Competition 1) You are studying competition between redbreast sunfish and green sunfish in a local stream. For the redbreast sunfish, K1-200 and α12-0.8. For the green sunfish, K2-150 and α21-0.6. Suppose the initial population sizes are 75 redbreast sunfish and 50 green sunfish. Graph the state space and isoclines for each species, and plot these initial population sizes. Predict the short-term dynamics of each population and the final outcome of interspecific competition. 2) You are studying competition between the invasive flathead catfish, Pylodictis olivaris, and the native channel catfish, Ictalurus punctatus, in a local iver. For the flathead catfish, K1- 500 and α12-0.8. For the channel catfish, K2-450 and α21-12. Suppose the initial population sizes are 75 flathead catfish and 500 channel catfish. Graph the state space and isoclines for each species in the space below, and plot these initial population sizes. Predict the short-term dynamics of each population and the final outcome of interspecific competition.

Answer 1

(1) N₁ = 75

K₁ = 200

A₁₂ = 0.8

N₂ = 50

K₂ = 150

A₂₁ = 0.6

N_{2 (eq)} = K₂-(a₁₂ N₁)

                = 90

When N₂ = 0; N₁ = K₂/a₁₂ = 187.8

When N₁=0; N₂= K₁/a₂₁ = 333.33

400 300 200 K2 100 Ka 100 K:/ α12 ро 300

When N₂ = 0, N₁ < K₁. This implies that the population of redbreast sunfish is growing

When N₁ = 0, N₂ > K₂. This implies that the population of green sunfish is shrinking.