How Populations Grow

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Population Biology Noun

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[pop-yuh-ley-shuhn bahy-ol-uh-jee]

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Population Biology

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The scientific study of populations of organisms, focusing on factors that affect their size, density, distribution, and growth.

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Example: This graph shows how the number of predators (lynx) and prey (hares) are linked; as the hare population grows, the lynx population follows, causing both to cycle.

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Geographic Range Noun

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[jee-uh-graf-ik reynj]

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Geographic Range

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The specific area or region where a particular species or population can be found living naturally.

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Example: This map shows the specific area in the Arctic where the polar bear population lives, which is its geographic range.

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Population Density Noun

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[pop-yuh-ley-shuhn den-si-tee]

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Population Density

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A measurement of the number of individuals of a particular species living within a specific unit of area.

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Example: This map shows population density across the U.S. Red and orange areas are crowded (high density), while green areas are sparsely populated (low density).

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Population Distribution Noun

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[pop-yuh-ley-shuhn dis-tri-byoo-shuhn]

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Population Distribution

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The pattern describing how individuals of a population are spaced out across the area they occupy.

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Example: A population of robins is clumped in the forest habitat where resources are available, showing an uneven pattern of population distribution across the landscape.

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Random Distribution Noun

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[ran-duhm dis-tri-byoo-shuhn]

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Random Distribution

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A spacing pattern where the position of each individual is independent of the others, with no clear pattern.

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Example: This diagram shows that in a random distribution, the position of each individual in a population is independent of the others, with no predictable pattern.

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Uniform Distribution Noun

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[yoo-nuh-fawrm dis-tri-byoo-shuhn]

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Uniform Distribution

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A spacing pattern where individuals are evenly distanced from each other, often resulting from competition for resources.

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Example: This image shows a uniform distribution, where individuals in a population, like these plants, are spaced evenly apart, often due to competition for resources.

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Clumped Distribution Noun

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[kluhmpd dis-tri-byoo-shuhn]

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Clumped Distribution

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A spacing pattern where individuals are aggregated in patches or groups, often around resources or for social reasons.

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Example: This image shows a population of organisms (yellow dots) clustered together near a resource, like a river, which is a common reason for clumped distribution.

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Age Structure Noun

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[eyj struhk-cher]

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Age Structure

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The distribution of individuals among various age groups, including the number of males and females in each group.

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Example: This population pyramid shows age structure by graphing the number of males and females in different age groups, from youngest at the bottom.

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Growth Rate Noun

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[grohth reyt]

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Growth Rate

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The rate at which a population's size changes over a specific period, indicating increase, decrease, or stability.

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Example: This diagram shows a population of tiny organisms, like bacteria, increasing over four time steps. Growth rate describes how quickly the population gets larger.

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Birthrate Noun

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[burth-reyt]

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Birthrate

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The number of live births per unit of population over a given period, indicating reproductive frequency.

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Example: This world map uses a color scale to show the birth rate (births per 1,000 people) in different countries, illustrating how this factor of population growth varies globally.