Type 2 survivorship curve

Definition

A Type 2 survivorship curve is a graphical representation of the mortality rate of a species that remains relatively constant throughout its life span. In this curve, individuals have an equal chance of dying at any age, meaning mortality is not strongly influenced by age, which often characterizes species with stable environments and moderate predation pressures.

5 Must Know Facts For Your Next Test

1. Type 2 survivorship curves are typically associated with organisms like birds and some small mammals, where individuals face constant predation risk throughout their lives.
2. In a Type 2 curve, the slope of the graph is linear, indicating a steady decline in the number of individuals as age increases.
3. This type of curve contrasts with Type 1 and Type 3 survivorship curves, which display different patterns of mortality related to age.
4. Species exhibiting a Type 2 survivorship curve often have stable populations, as they are not overly impacted by environmental changes during specific life stages.
5. Understanding Type 2 survivorship helps ecologists predict population trends and the effects of environmental changes on various species.

Review Questions

• How does a Type 2 survivorship curve differ from Type 1 and Type 3 curves in terms of mortality patterns?
  • A Type 2 survivorship curve features a linear decline in survivorship, indicating that individuals face a consistent risk of mortality at any age. In contrast, Type 1 curves show high survival rates during early and middle life stages but experience increased mortality at older ages, typical of larger mammals. Type 3 curves exhibit high mortality rates in early life stages with fewer surviving to adulthood, common among many fish and amphibians. These differences highlight how species adapt their life strategies based on environmental pressures and reproductive success.
• What are some ecological implications of having a population that follows a Type 2 survivorship curve?
  • Populations following a Type 2 survivorship curve often indicate stable ecosystems where predation and environmental factors are relatively balanced. This stability allows for consistent population sizes, as these species can maintain their numbers despite moderate mortality rates. Ecologically, it means these species may play critical roles in their habitats, such as maintaining food webs. Additionally, understanding these dynamics helps in managing conservation efforts and predicting how populations may respond to environmental changes.
• Evaluate how knowledge of Type 2 survivorship curves can inform conservation strategies for vulnerable species.
  • Knowledge of Type 2 survivorship curves can significantly enhance conservation strategies by allowing ecologists to identify critical life stages at risk of mortality. Since these species experience constant predation or environmental pressures throughout their lives, targeted interventions can be developed to protect them during vulnerable periods. For example, if certain habitats are crucial for breeding or feeding and contribute to higher survival rates, conservation efforts can focus on preserving those areas. This informed approach ensures resources are allocated effectively to help maintain stable populations in the face of habitat loss or climate change.

Related terms

Survivorship: The probability of an individual organism surviving to a particular age, often used in ecological studies to understand population dynamics.

Life Table: A table that shows the mortality and survival rates for a population at different ages, used to calculate survivorship curves.

Reproductive Strategies: The strategies that organisms use to reproduce, which can affect their survivorship curves, including r-selected and K-selected species.