Problem 13 - Campbell Biology Concepts & Connections

Question

The mountain gorilla, spotted owl, giant panda, snow leopard, and grizzly bear are all endangered by human encroachment on their environments. Another thing these animals have in common is their \(K\) -selected life history traits. Why might they be more easily endangered than animals with \(r\) -selected life history traits? What general type of survivorship curve would you expect these species to exhibit? Explain your answer.

Step-by-Step Solution

Answer

K-selected species are easily endangered due to slow reproduction and need for stable environments. They show Type I survivorship curves.

Step 1: Understand K-selected vs. r-selected Traits

K-selected species, like mountain gorillas and giant pandas, have life history traits characterized by producing few offspring with higher probabilities of survival. They invest significant resources in nurturing their young. In contrast, r-selected species produce many offspring but invest little in each, with lower probabilities of survival for each individual.

Step 2: Identify Vulnerability Factors

K-selected species are more vulnerable to endangerment because their slow reproduction rates make it difficult to recover from population declines. They need stable environments, which are often disrupted by human activities.

Step 3: Survivorship Curve Analysis

These species typically exhibit Type I survivorship curves, where most individuals survive to old age. This curve reflects low mortality rates in early and middle life but higher mortality at older ages.

Key Concepts

Endangered Species

Endangered species are animals or plants that are at risk of extinction. Many factors contribute to a species becoming endangered. Some common causes include:

• Habitat loss
• Introduction of invasive species
• Pollution
• Over-harvesting
• Climate change

These threats are often magnified for K-selected species like the mountain gorilla, spotted owl, or giant panda. These animals have slow reproductive rates and invest lots of resources in a small number of offspring. Because it takes a long time for their populations to recover, any additional pressure can push them toward extinction more quickly.

Human Encroachment

Human encroachment refers to the expansion of human activities into natural habitats. This encroachment has devastating effects on wildlife, mainly by:

• Destroying habitats
• Disrupting food chains
• Introducing pollution
• Causing direct harm through hunting or vehicle collisions

K-selected species, which require stable environments, suffer more from these disruptions. Since humans also need space for agriculture, urban development, and infrastructure, these activities often lead to habitat fragmentation and loss, putting these species at even greater risk.

Survivorship Curves

Survivorship curves are graphical representations of the number of individuals surviving at each age for a given species. There are three main types of survivorship curves:

• Type I: High survival in early and middle life, followed by a rapid decline in later life. Common in K-selected species.
• Type II: A constant death rate at all ages. Often seen in birds and some reptiles.
• Type III: High mortality in early life with a few individuals reaching adulthood. Typical for r-selected species.

The mountain gorilla and other K-selected species generally exhibit Type I survivorship curves. This means that most offspring survive to adulthood, but once they reach old age, their mortality rate increases significantly. This pattern further emphasizes their vulnerability, as losing adult individuals can have substantial impacts on population numbers.

Conservation Biology

Conservation biology is the science of protecting and managing biodiversity. It plays a vital role in preventing species from becoming extinct. Key strategies include:

• Creating and enforcing protected areas like national parks and wildlife reserves
• Restoring degraded habitats
• Developing captive breeding programs
• Implementing laws and regulations to limit pollution and hunting
• Raising public awareness and education

For K-selected species, conservation efforts often focus on maintaining stable environments and minimizing human impacts. Effective conservation policies are critical for ensuring these species have a chance to thrive and avoid extinction.