Name: life history strategies and survivorship
Uploaded: 2026-06-01T06:28:26.918Z
Duration: 1 min 29 s
Channel: JoVE

K12 Standards

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NC K-12 Science Standard Course of Study

9-12

Biology

ecosystems-interactions-energy-and-dynamics

Ecosystems- Interactions, Energy, and Dynamics

LS.Bio.4.2

Life Histories

All the events that affect an organism&#x27;s survival and reproduction make up its life history. The pattern of these events varies across species, even among organisms living in the same habitat.For example, a small snail matures quickly and produces thousands of eggs.Most of these offspring die early in life, so producing many eggs increases the chance that a few survive to adulthood.This pattern reflects an r-selected strategy, a term used to describe species that produce many offspring and provide little parental care.Species with this strategy often show a Type III survivorship curve, characterized by high mortality early in life. Individuals that survive the early stages have a much higher chance of reaching adulthood.On the other hand, howler monkeys follow a K-selected strategy. They mature slowly, have only a few offspring over a long lifespan, and provide years of parental care to help ensure their survival.These primates show a Type I survivorship curve, characterized by high survival rates during early and middle life and high mortality in old age.The final survivorship curve, Type II, shows an equal probability of survival and mortality throughout an organism&#x27;s life cycle.For example, many songbirds face similar threats from predators, disease, and environmental stress at every age. Because of that, their survivorship curve forms a steady diagonal line.These survivorship curves show how different species adopt different strategies to balance their survival and reproduction.

life histories

Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented by two primary reproductive strategies; K-strategists produce few offspring but provide substantial parental support, whereas r-strategists produce much progeny that receives little care. These strategies are related to an organism&#x2019;s survival likelihood across its lifespan, which is represented by a survivorship curve. Three general types of survivorship curves are exhibited by organisms that: tend to live long lives (Type I, K-strategists); are equally likely to die at all ages (Type II); or have high early mortality rates, but long lifespans if they survive into adulthood (Type III, r-strategists).<h4>Life History Strategies Reflect a Trade-Off between Offspring &#x201C;Quantity&#x201D; and &#x201C;Quality&#x201D;</h4>An organism&#x2019;s life history includes all the events occurring across its lifespan, including birth, development, sexual maturation, reproduction, and death. Trade-offs involving the patterns and timing of life history events (notably survival and reproduction) across different ages and developmental stages represent different life history strategies. R-strategists and K-strategists make distinct reproductive compromises between the number of offspring and level of parental care, or offspring quantity versus quality. R-strategists (r for rate) tend to have high fecundity (reproductive potential) and produce many offspring that are widely dispersed, receive little parental care, and have low early survival rates. R-strategists typically thrive in unpredictable environments, mature early and have small bodies. K-strategists (K for Kapazit&#xE4;tsgrenze, or capacity-limit in German) produce fewer offspring and devote more parental care than r-strategists, and their progeny thus have higher early survival rates. K-strategists prosper in stable environments. Importantly, most organisms are not strict r- or K- strategists, but lie somewhere on a continuum of these traits. For example, sea turtles have long lifespans and strong competitiveness (K traits), yet produce many offspring that receive little parental care (r traits).<h4>Population Survival and Growth Can Be Visualized on Survivorship Curves and Age Structure Diagrams</h4>A survivorship curve displays the percentage of a population surviving (y-axis) at different age intervals (x-axis). Of the three general types of survivorship curves, two correspond to K- and r- strategists. K-strategists, including humans and most primates and zoo animals, exhibit Type I survivorship and tend to die when elderly. Species displaying Type II survivorship have an equal chance of survival at each age interval. Type II survivorship is highly theoretical, with few real-world examples. Hydras, gulls, and American robins exhibit fairly linear survivorship curves, and rodents, rabbits, many adult birds, and some turtles exhibit a sigmoid or concave curve that approaches linearity. R-strategists, including trees, marine invertebrates, fish, and some insects, display Type III survivorship. These organisms often die young, but those that survive to adulthood generally live long lives. Most species display some combination of these patterns. For example, a species displaying Type III juvenile survivorship may exhibit Type II adult survivorship. On survivorship curves, the number of surviving individuals (y-axis) is often plotted on a logarithmic scale to better display per capita (proportion) effects and allow comparisons with idealized Types I, II, and III.An age structure diagram shows the proportion of a population (x-axis) at each age interval (y-axis) and can be used to predict whether a population will shrink or grow. For example, greater growth would be expected in a population with more females and young individuals. Different diagram shapes represent distinct patterns of likely population changes (growing, stable, or shrinking).

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Education

JoVE Core

Ecology

Population and Community Ecology

KEY TERMS AND CONCEPTS

life history strategies and survivorship

Life history strategies show how organisms balance survival and reproduction across a lifetime. An organism’s life history includes birth, growth, sexual maturation, reproduction, and death. These patterns reflect trade-offs in how much energy and resources go to making offspring and caring for them.

R-strategists and K-strategists show two common reproductive strategies. R-strategists, with r standing for rate, have high fecundity, or reproductive potential. They produce many offspring that are widely dispersed, get little parental care, and often have low early survival. They usually do well in unpredictable environments, mature early, and are often small-bodied. K-strategists, with K from the German word for capacity limit, produce fewer offspring and invest more care in them. Their young usually survive better early in life, and K-strategists tend to do well in stable environments. Most organisms fall somewhere along a continuum between these two extremes. Sea turtles are a good example because they show long life and strong competition, which are K traits, but they also produce many offspring with little parental care, which is an r trait.

These life history patterns are shown with survivorship curves. A survivorship curve plots the percentage of a population that survives at different ages. Type I curves fit K-strategists such as humans and most primates and zoo animals. These species tend to survive to old age and die later in life. Type II curves show an equal chance of dying at each age, but this pattern is mostly theoretical and has few real-world examples. Hydras, gulls, and American robins show fairly linear survivorship curves, and rodents, rabbits, many adult birds, and some turtles show curves that are sigmoid or concave but move toward linearity.

Type III curves fit r-strategists such as trees, marine invertebrates, fish, and some insects. These organisms often die young, but those that survive to adulthood may live a long time. Most species do not fit only one pattern. Some have Type III survivorship when young and Type II survivorship as adults. On survivorship curves, the number of survivors is often shown on a logarithmic scale. This makes proportional change easier to compare across the idealized Types I, II, and III.

Age structure diagrams give another way to predict population change. An age structure diagram shows the proportion of a population at each age interval. It can help predict whether a population will grow, stay stable, or shrink. A population with more females and more young individuals is more likely to grow. The shape of the diagram reveals the likely trend in population size.

Life History Strategies and Survivorship

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Life history strategies show how organisms balance survival and reproduction across a lifetime. An organism’s life history includes birth, growth, sexual maturation, reproduction, and death. These patterns reflect trade-offs in how much energy and resources go to making offspring and caring for them. R-strategists and K-strategists show two common reproductive strategies. R-strategists, with r standing for rate, have high fecundity, or reproductive potential. They produce many offspring that...

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ecological succession

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key terms and concepts

Explore r- and K-strategists, survivorship curves, and age structure diagrams to see how life history traits affect survival and population growth.

Life History Strategies and Survivorship | JoVE K12

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biology

Pennsylvania State Academic Standards

Life Science

interdependent-relationships-in-ecosystems

Interdependent Relationships in Ecosystems

3.1.9-12.I

3.1.9-12.L

3.1.9-12.M

Louisiana Student Standards for Science

High School

Life Sciences

Ecosystems: Interactions, Energy And Dynamics

HS-LS2-1

Environmental Science

HS-LS2-4

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Diversity And Interdependence Of Life

Ecosystems

Tennessee Academic Standards

Ecosystems: Interactions, Energy, and Dynamics

BIO1.LS2.5

Virginia  Standards of Learning

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BIO.7

BIO.7.b

BIO.8

BIO.8.a

LS.8

LS.8.b

Minnesota Academic Standards in Science

3.2.1 9L.3.2.1.4

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New Jersey Student Learning Standards for Science

Alabama Course of Study Science

Ecosystems: Interactions Energy and Dynamics

9-12.B.2.6

Unity and Diversity

9-12.EVS.2.3

Next Generation Science Standards

HS-LS2-6

Florida Department of Education

SC.912.L.17

SC.912.L.17.5

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South Carolina College and Career Ready Science Standards

B-LS2-2.

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New York State Science Learning Standards

Earth and Space Sciences

Earth’s Systems

HS-ESS2-7.

Georgia Standards of Excellence

SEC1.

SEC1.a

What are Biogeochemical Cycles?

The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited ...

The Water Cycle

The Earth&rsquo;s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, ...

The Carbon Cycle

Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among ...

The Nitrogen Cycle

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Use models to illustrate how processes in organisms contribute to the flow of energy and the cycling of matter within an ecosystem.

LS.Bio.4.1

What are Populations and Communities?

Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting ...

Distribution and Dispersion

Ecology is the study of how organisms interact with their environment and with one another. An important aspect of ecology is understanding where species ...

Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented ...

Energy Budgets and Reproductive Strategies

Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of ...

Population Growth

Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with ...

Use models to explain the relationship between the flow of energy and cycling of matter among organisms in an ecosystem.

Ecological Niches

All organisms have a position within an ecosystem. The complete set of living and nonliving factors&#x2014;including food resources, climate, and ...

Ecological Succession

Ecological succession is influenced by the processes of facilitation, inhibition, and toleration. Facilitation occurs when early successional species ...

Keystone Species

Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ...

Symbiosis

Symbiotic relationships are long-term, close interactions between individuals of different species that affect the distribution and abundance of those ...

Competition

When organisms require the same limited resources within an environment, they may have to compete for them. Competition is a net-negative interaction. ...

Predator-Prey Interactions

Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction ...

Ecological Disturbance

An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced ...

Use mathematics and computational thinking to explain how interactions between organisms (predator/prey, competition) affect carrying capacity and maintain stability in an ecosystem.

LS.Bio.5.1

What is Biodiversity?

Biodiversity describes the variety of living things at multiple organizational levels: genetic, species and ecosystem diversity. Species diversity ...

Threats to Biodiversity

There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species ...

Biodiversity and Human Values

Human civilization relies on biodiversity in many ways. Sudden changes in species biodiversity result in environmental changes that can modify weather ...

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Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the ...

Sustainable Development

As the human population continues to grow and use resources, we must be mindful of our planet&rsquo;s natural limits. Sustainable development provides a ...

Conservation of Small Populations

Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens ...

What is Weather?

Overview

Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the ...

Global Climate Change

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global ...

Conservation of Declining Populations

Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent ...

Habitat Fragmentation

Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land ...

Engage in argument from evidence to evaluate various solutions to reduce the impact of human activities on biodiversity and ecosystem health.

LS.Bio.5.2

Analyze the relationships between matter and energy within ecosystems.

Life History Strategies and Survivorship

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