Contextualization

Survivorship curves are a fundamental concept in the field of ecology, specifically in understanding the dynamics of populations. They represent the number of individuals surviving at each age in a given population and are a visual representation of a species' mortality rates throughout their lifespan. This curve is a powerful tool for biologists to understand the life history of a species, which includes aspects such as reproductive strategy and lifespan.

There are three main types of survivorship curves:

1. Type I is characterized by high survival rates throughout most of the lifespan, with a sharp decline in survival in old age. This pattern is typically observed in large mammals, including humans, where individuals have a high chance of surviving to adulthood and senescence (old age).

2. Type II shows a relatively constant mortality rate throughout the organism's lifespan. This pattern is often seen in birds and small mammals, where the chance of survival does not depend on the individual's age.

3. Type III is characterized by high mortality rates early in life, followed by a period of relatively low death rates later in life. This pattern is frequently observed in species that produce a large number of offspring, such as fish and insects.

Survivorship curves are not only interesting from a biological perspective but also have real-world applications. They can help us understand and predict the population dynamics of species, which is crucial for conservation efforts. They can also be used to study the impact of environmental factors, such as climate change or pollution, on populations. In addition, survivorship curves are often used in actuarial science to determine life insurance premiums and pension plans.

To delve deeper into this topic, students can use the following resources:

1. Khan Academy's course on population ecology
2. BBC Bitesize's section on survivorship curves
3. National Geographic's article on understanding survivorship curves
4. Video from the Amoeba Sisters on survivorship curves

By understanding survivorship curves, students will gain a deeper appreciation for the complexity and beauty of life's diversity, and the delicate balance that exists within ecosystems. They will also develop critical thinking and problem-solving skills as they apply this knowledge to real-world scenarios and propose solutions for population management and conservation.

Practical Activity

Activity Title: "Population Dynamics: A Tale of Three Survivorship Curves"

Objective:

To understand the concept of survivorship curves and their implications in population dynamics and conservation efforts.

Description:

In this project, groups of 3 to 5 students will simulate and analyze the survivorship curves of three fictional species. The students will need to create their own survivorship curves based on the life histories of the species, and then analyze the implications of their curves in terms of reproductive strategy, lifespan, and population dynamics. Finally, they will propose ways in which the management and conservation of each species could be approached based on their survivorship curves.

Necessary Materials:

• Paper and writing materials for sketching and note-taking.
• Access to a computer with an internet connection for research.
• Presentation software for the final report (PowerPoint, Google Slides, etc.).

Detailed Step-by-Step:

1. Research Phase (2 hours): Each group will be assigned three fictional species. The students must research and understand the life history of these species, including their reproductive strategies, typical lifespan, and common causes of mortality.

2. Curve Creation (2 hours): Based on their research, each group will create a survivorship curve for each of their assigned species. They can use any format they prefer, such as a line graph or histogram. The x-axis should represent age, and the y-axis should represent the number or proportion of individuals surviving.

3. Curve Analysis (1 hour): After creating the curves, the students will analyze them. They should identify the type of survivorship curve each species follows and explain why they chose that specific type. They should also discuss how the curve relates to the species' life history traits and what it might indicate about their population dynamics.

4. Management and Conservation (1 hour): Based on their analysis, the students will propose management and conservation strategies for each species. They should consider factors such as the species' reproductive strategy, lifespan, and population dynamics. The strategies can be practical (e.g., protected breeding grounds) or theoretical (e.g., changing hunting regulations).

5. Report Writing (2 hours): Finally, the group will compile their research, curve creation, analysis, and conservation proposals into a report. The report should be divided into four main sections: Introduction, Development, Conclusions, and Used Bibliography. In the introduction, they should explain the concept of survivorship curves and their relevance. The development section should detail the research, curve creation, and analysis steps. The conclusion should summarize their findings and discuss the implications for population management and conservation. They should also indicate the sources they relied on for their research in the bibliography.

Project Deliverables:

• Three survivorship curves (one for each assigned species) with a detailed analysis of each curve.
• A written report detailing the project process and findings. The report should include an introduction, development, conclusion, and bibliography.
• A group presentation of the project, including a discussion of their curves and their proposed management and conservation strategies.

The written report and the group presentation should complement each other. The report will provide the detailed explanation of the project, while the presentation will allow the students to demonstrate their understanding of the concepts and their ability to communicate them effectively.