Contents
- 1 What are survivorship curves and what do they show us about a population?
- 2 What do the shapes of the survivorship curves tell us about patterns of survival and mortality?
- 3 Why is it important to understand survivorship patterns of populations?
- 4 What type of survivorship curves do humans typically display?
- 5 How are Survivorship curves and age-sex pyramids related?
- 6 What do animals have a type 2 survivorship curve?
What are survivorship curves and what do they show us about a population?
A survivorship curve is a graph showing the number or proportion of individuals surviving to each age for a given species or group (e.g. males or females). Survivorship curves can be constructed for a given cohort (a group of individuals of roughly the same age) based on a life table.
What do the shapes of the survivorship curves tell us about patterns of survival and mortality?
Survivorship curves are tools used by biologists to describe the typical mortality patterns of species. Type II curves depict individuals whose chance of survival is independent of age. Type III curves depict individuals that mostly die in the early stages of their life.
How does survivorship relate to population change?
A survivorship curve is the graphic representation of the number of individuals in a population that can be expected to survive to any specific age. In some species that produce many offspring but provide little care for them (r-selected species), mortality is greatest among the youngest individuals.
Why is it important to understand survivorship patterns of populations?
Another tool used by population ecologists is a survivorship curve, which is a graph of the number of individuals surviving at each age interval versus time. These curves allow us to compare the life histories of different populations (Figure 3).
What type of survivorship curves do humans typically display?
Humans and most primates have a Type I survivorship curve. In a Type I curve, organisms tend not to die when they are young or middle-aged but, instead, die when they become elderly.
What is the definition of a survivorship curve?
Definition of Survivorship curve: A survivorship curve is a graph showing the number or proportion of individuals surviving to each age for a given species or group. For making survivorship curves, ecologists identify a cohort, which is a group of individuals of the same species, in the same population, born at the same time.
Survivorship curves are graphs that show what fraction of a population survives from one age to the next. An age-sex pyramid is a “snapshot” of a population in time showing how its members are distributed among age and sex categories.
What do animals have a type 2 survivorship curve?
A type II survivorship curve shows a roughly constant mortality rate for the species through its entire life. This means that the individual’s chance of dying is independent of their age. Type II survivorship curves are plotted as a diagonal line going downward on a graph.
What kind of survivorship curve do primates have?
Type I. Humans and most primates have a Type I survivorship curve. In a Type I curve, organisms tend not to die when they are young or middle-aged but, instead, die when they become elderly. Species with Type I curves usually have small numbers of offspring and provide lots of parental care to make sure those offspring survive.