Question

________ is a density-independent factor that influences population growth. a. Resource competition c. Predation b. Infectious disease d. Harsh weather

Short answer

Harsh weather (d) is a density-independent factor influencing population growth.

Step-by-step solution

Understanding the Question

We need to identify which factor from the options provided is a density-independent factor influencing population growth. Density-independent factors operate regardless of population density.

Analyzing the Options

Let's consider each option in relation to whether they are density-dependent or density-independent. - a. Resource competition: This is density-dependent because it intensifies as the population grows. - b. Infectious disease: This is density-dependent as it spreads more easily in larger populations. - c. Predation: This can be density-dependent since predators typically focus on denser populations for more prey. - d. Harsh weather: This is density-independent as it affects populations regardless of their size.

Identifying the Density-Independent Factor

From the options analyzed, 'harsh weather' (option d) is the only one that affects populations regardless of their size and density, thus it is a density-independent factor.

Key concepts

Population Growth

Population growth is the change in the number of individuals in a population over time. It can be influenced by various factors such as birth rates, death rates, immigration, and emigration. In simple terms, if more individuals are born or migrate into the population than die or leave, the population grows. Conversely, if deaths and emigration exceed births and immigration, the population shrinks.

Population growth can also be affected by both biotic (living) and abiotic (non-living) factors, and understanding these can help predict future changes. The balance of growth can be impacted by availability of resources, environmental conditions, and predation pressures, among others.

Density-Dependent Factors

Density-dependent factors are factors that affect population growth based on the population density. They become more intense as the population size increases and can limit the overall population growth. These factors are mostly biotic and include:

• Competition for Resources: As population density increases, individuals compete more for limited resources like food, water, and shelter.
• Predation: Denser populations often attract more predators because they have more potential prey available.
• Disease: Diseases spread more efficiently in crowded populations due to closer and more frequent contact between individuals.

Density-dependent factors help to stabilize a population size by slowing its rate of growth as it reaches the environment's carrying capacity.

Harsh Weather Effects

Harsh weather effects are considered density-independent factors because they can affect a population regardless of its size. These can include extreme temperatures, droughts, floods, and storms. Unlike density-dependent factors, the impact of harsh weather is usually unpredictable and can cause significant population fluctuations.

• Extreme Temperatures: Very high or low temperatures can be deadly to individuals not adapted to such conditions.
• Droughts: Lack of water can lead to reduced plant growth, which affects herbivores and subsequently, carnivores higher up in the food web.
• Floods and Storms: Destructive weather events can destroy habitats and cause immediate declines in population numbers.

These factors demonstrate how external environmental conditions can shape population dynamics without regard to population density.

Ecological Factors

Ecological factors include both density-dependent and density-independent factors that influence how populations grow and interact with their environment. Understanding these helps in forecasting population changes and managing wildlife resources effectively.

Major ecological factors can include:

• Resource Availability: Essential for survival and reproduction, resource availability can dictate how large a population can grow.
• Climate: Climate patterns over time can influence natural habitat conditions, affecting populations in those habitats.
• Human Activity: Activities such as deforestation, pollution, and urbanization can alter ecosystems and influence population growth, often negatively.

Ecologists study these factors to develop conservation strategies and to understand the natural world's complexity better. Ecological factors illustrate how a network of interactions contributes to the dynamic nature of ecosystems.