Problem 7 - Biology Today and Tomorrow with Physiology

Question

Members of a species with an __________ life history have many off-spring and invest little in each one. a. equilibrial b. opportunistic

Step-by-Step Solution

Answer

The correct answer is b. opportunistic.

Step 1: Understand the Terms

In this exercise, we are comparing two types of life history strategies. 'Equilibrial' life history refers to species that produce fewer offspring but invest more in the care and survival of each. In contrast, an 'opportunistic' life history involves producing many offspring with little investment in each.

Step 2: Analyze the Context

The exercise asks us to identify which type of life history matches the description of a species having many offspring with little investment in each. This aligns with the opportunistic strategy, as these species tend to focus on quantity over quality.

Step 3: Select the Correct Answer

Based on the analysis, the description given in the exercise fits the 'opportunistic' life history strategy, which emphasizes producing a large number of offspring with minimal parental care or resources allocated to each one.

Key Concepts

Equilibrial Strategy

Species with an equilibrial strategy focus on quality over quantity when it comes to reproduction. They typically have fewer offspring but invest significantly in each one's upbringing. This means providing care, protection, and resources to ensure that these few offspring have a higher chance of reaching maturity and reproducing successfully themselves.
This strategy often occurs in stable environments where resources are reliable. It allows parents to exert more energy and resources per offspring, increasing the chances of survival in competitive or resource-scarce settings. For example, species like elephants and humans, which invest heavily in raising each young, practicing behaviors such as teaching, nurturing, and protecting. These efforts significantly enhance the offspring's survival odds.

• Fewer offspring.
• High investment in each individual.
• Common in stable environments.
• Parental care and nurturing.

Equilibrial strategists are usually long-lived with slower reproduction rates, focusing on long-term survival and success.

Opportunistic Strategy

Species adopting an opportunistic strategy opt for quantity over quality in their reproductive practices. They tend to produce many offspring but invest very little in the care or resources for each one. This strategy is ideal in fluctuating or unpredictable environments where the survival odds are uncertain.
The idea is that by producing numerous offspring, at least some will survive to adulthood despite minimal parental involvement. This method is common among species such as insects, many fish, and some plants. These organisms capitalize on their ability to reproduce quickly and in large numbers, spreading the risk across many individuals.

• Many offspring produced.
• Low individual investment.
• Optimal in unpredictable environments.
• Minimal parental care.

Opportunistic species often have shorter lifespans but high reproductive rates, allowing them to take advantage of favorable conditions when they arise.

Reproductive Investment

Reproductive investment refers to the amount of energy, time, and resources a species allocates to ensure the survival and success of its offspring. This concept is central to understanding different life history strategies as it affects evolutionary and ecological dynamics.
High reproductive investment is typical of equilibrial species where the focus is on ensuring the offspring have the best possible chance of surviving to adulthood. This might include extended periods of parental care, protection, and even teaching. Such an investment is essential when offspring survival hinges more on parental effort compared to sheer numbers.

• Energy and resources allocated per offspring.
• High investment increases survival chances.
• Varies across species based on environmental demands.

Conversely, low reproductive investment characterizes opportunistic species where the emphasis is on producing as many offspring as possible. The sheer number of offspring ensures that some will survive despite minimal individual attention.