Lesson 4.3 - Reproductive Rate

You learned about the relationship between predator-prey populations.  You also learned that other limiting factors affect the populations of organisms.  Why are some species so slow to increase their population when conditions are right while other species can multiply quickly to enormous numbers?  

Read Reproductive Rate on page 267 in your textbook. Then, answer the following questions.

 

Question 1. What does reproductive rate mean?

Question 2. When will a population with a high reproductive rate increase rapidly?

Question 3. When will a population with a low reproductive rate increase rapidly?

Question 4. What can you say about the way a species cares for its young just by looking at the reproductive rate?

Question 5. Why is the Earth not overrun with flies and ants when they have such high reproductive rates?

Question 6. What do species with low reproductive rates do to ensure the survival of the species?

Question 7. Do you think other species would show similar cycles in their populations?

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What does reproductive rate mean?

In the textbook, reproductive rate means the rate at which organisms can reproduce.

Question 2. When will a population with a high reproductive rate increase rapidly?

A population with a high reproductive rate such as houseflies increase rapidly when the limiting factors favour reproduction and survival.  The supply of food, water, and other other abiotic limiting factors must be very good.  The biotic factors such as predators and disease must be very low.  Then, conditions are ripe for a population explosion.  The locust swarms in Africa in 2004 are an example of this.

Question 3. When will a population with a low reproductive rate increase rapidly?

A population with a low reproductive rate will never increase rapidly.  There are not enough offspring produced to have a rapid increase in population.  What can happen is that the population continues to increase slowly when conditions are right.

Question 4. What can you say about the way a species cares for its young just by looking at the reproductive rate?  Give an example of a species with a low reproductive rate and an example of a species with a high reproductive rate.

In general, if a species cares for its young, the reproductive rate is low.  Species that do not care for their young usually have very high reproductive rates.  The exceptions are communal insects such as ants, termites, bees, and wasps.  An elephant is a species with a low reproductive rate.  A species with a high reproductive rate is the housefly.

Question 5. Why is the Earth not overrun with flies and ants when they have such high reproductive rates?

The Earth is not overrun with species of organisms that have very high rates of reproduction because they have a short life span, limited food supply, and many biotic limiting factors such as predators as well as abiotic limiting factors such as space.

Question 6. What do species with low reproductive rates do to ensure the survival of the species?

Species with low reproductive rates take care of their young to ensure the survival of the species.

 


Now, do Assignment 13D.  Page forward to access it.