Type 3 survivorship curve

Definition

A Type 3 survivorship curve represents a pattern of survival where most individuals die young, but if they survive to a certain age, their chances of living longer increase significantly. This curve is typically characterized by high mortality rates during early life stages, followed by a decline in mortality once individuals reach maturity. Organisms that exhibit this curve often produce large numbers of offspring, relying on the survival of just a few to sustain their population.

5 Must Know Facts For Your Next Test

1. Type 3 survivorship curves are commonly found in species that produce a high number of offspring, such as fish and many invertebrates.
2. In this curve, mortality is highest during the early stages of life, with very few individuals surviving to adulthood compared to those that are born.
3. Once individuals reach a certain age or stage in life, their risk of dying decreases significantly, leading to a longer life expectancy.
4. Species with Type 3 survivorship strategies often invest little parental care into their young, instead relying on sheer numbers to ensure some survive.
5. The curve contrasts with Type 1 and Type 2 survivorship curves, where organisms typically have higher survival rates throughout their life cycle.

Review Questions

• How does the reproductive strategy of organisms with a Type 3 survivorship curve impact their population dynamics?
  • Organisms with a Type 3 survivorship curve tend to have high fecundity, producing numerous offspring with the understanding that most will not survive to adulthood. This reproductive strategy leads to fluctuations in population dynamics, where populations can grow rapidly during favorable conditions but may also experience significant declines when environmental conditions are unfavorable. The high mortality rate among the young means that populations must consistently produce many offspring to maintain their numbers.
• Compare and contrast the Type 3 survivorship curve with the Type 1 and Type 2 curves in terms of survival patterns and reproductive strategies.
  • While Type 3 survivorship curves display high mortality in early life stages with few surviving to adulthood, Type 1 curves illustrate the opposite pattern where most individuals survive through infancy and experience lower mortality rates later in life. Type 2 curves represent a more constant mortality rate across all ages. The reproductive strategies also differ: Type 1 species often invest heavily in parental care to ensure survival, whereas Type 3 species focus on producing large numbers of offspring with little care given, leading to different survival outcomes based on environmental pressures.
• Evaluate how environmental factors may influence the characteristics of a Type 3 survivorship curve in certain populations.
  • Environmental factors such as predation rates, availability of resources, and habitat conditions can significantly shape the characteristics of a Type 3 survivorship curve. For example, if predation pressure is high on young individuals, it could lead to even greater mortality rates in early life stages, intensifying the curve's shape. Conversely, if resource availability improves or there are fewer predators, more young may survive to maturity. This flexibility shows how populations adapt their reproductive strategies and survival tactics based on their changing environment.

Related terms

Survivorship: The probability of an individual organism surviving to a particular age.

Fecundity: The potential reproductive capacity of an organism or population, often measured as the number of offspring produced.

Life History Strategy: The overall pattern of traits that relate to growth, reproduction, and survival within a species.