Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Conservation of Declining Populations

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 populations from going extinct.

Population Growth

Population Growth

Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with unlimited resources, populations can increase exponentially, which plots as a J-shaped growth rate curve of population size against time. This type of curve is characteristic of newly-introduced invasive species, or populations that have suffered catastrophic declines and are rebounding.However, realistic environmental conditions limit the number of...

Conservation of Small Populations

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 the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...

Threats to Biodiversity

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 that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...

Genetic Drift

Genetic Drift

Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...

Limits to Natural Selection

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.For one, natural selection can only act upon existing genetic variation. Hypothetically, redtusks may enhance elephant survival by deterring ivory-seeking poachers. However, if there are no gene variants—or alleles—for redtusks, natural selection cannot increase the prevalence of...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Four-dimensional diffusion-weighted magnetic resonance imaging for stereotactic body radiation therapy in patients with abdominal cancer: abridged secondary publication.

Hong Kong medical journal = Xianggang yi xue za zhi·2023

Same author

Risk of epilepsy in surgical patients undergoing general or neuraxial anaesthesia.

Anaesthesia·2017

Same author

Forensic Science in Support of Wildlife Conservation Efforts - Developments in Morphological and Chemical Approaches in Taiwan.

Forensic science review·2015

Same author

Factorial analysis of variables influencing mechanical characteristics of a post used to restore a root filled premolar using the finite element stress analysis combined with the Taguchi method.

International endodontic journal·2015

Same author

Photon bunching in cathodoluminescence.

Physical review letters·2015

Same author

Ambient pressure structural quantum critical point in the phase diagram of (Ca(x)Sr(1-x))(3)Rh(4)Sn(13).

Physical review letters·2015

Same journal

Extreme Weather and Mortality of Vulnerable Urban Populations: An Examination of Temperature and Unclaimed Deaths in New York City.

Demography·2026

Same journal

Overlooked Potential? Childcare Services and Ukrainian Refugee Mothers in Germany.

Demography·2026

Same journal

Effect of First Births on Women's Employment in a Low-Income Context: Research Note Using Panel Data From Nepal.

Demography·2026

Same journal

Decomposing Differences in Cohort Health Expectancy by Cause and Age With Longitudinal Data.

Demography·2026

Same journal

Wildfires and Birth Outcomes: Evidence From Spain.

Demography·2026

Same journal

The Effect of the Great Recession on U.S. Fertility: Causal Estimates From a Novel Cohort Discontinuity Design.

Demography·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Jun 4, 2026

Single-cell Profiling of Developing and Mature Retinal Neurons

Single-cell Profiling of Developing and Mature Retinal Neurons

Published on: April 19, 2012

Natural population decrease in Iowa counties.

¹Department of Sociology and Anthropology Iowa, State University, 50010, Ames, Iowa.

|February 1, 2011

Summary

This summary is machine-generated.

Rural Iowa counties experience natural population decrease primarily due to out-migration, not low fertility. This demographic shift impacts county characteristics and birth-death ratios.

More Related Videos

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Published on: November 1, 2017

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Published on: July 30, 2014

Related Experiment Videos

Last Updated: Jun 4, 2026

Single-cell Profiling of Developing and Mature Retinal Neurons

Single-cell Profiling of Developing and Mature Retinal Neurons

Published on: April 19, 2012

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Published on: November 1, 2017

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Published on: July 30, 2014

Area of Science:

Demography
Sociology
Population Studies

Background:

Follows previous studies by Dorn and Beale on population dynamics.
Investigates factors contributing to natural population decrease in Iowa counties.
Highlights distinct demographic and socioeconomic differences between counties with natural increase and decrease.

Purpose of the Study:

To analyze the roles of migration and fertility in causing natural population decrease in Iowa counties.
To differentiate between Iowa counties exhibiting natural decrease versus natural increase.
To understand the relationship between out-migration, fertility rates, and population imbalance.

Main Methods:

Utilized data from population censuses and vital statistics.
Compared demographic and socioeconomic characteristics of different county groups.
Examined the influence of out-migration and fertility on birth-death ratios.

Main Results:

Out-migration is the dominant factor driving natural population decrease in rural Iowa.
Sustained net out-migration more significantly impacts natural decrease in low-fertility counties.
Low fertility contributes to population imbalance but its precise influence is confounded by fertility and Catholic Church membership correlation.

Conclusions:

Out-migration is the primary driver of natural population decrease in Iowa counties.
Fertility is a contributing factor, but its impact is complex and intertwined with other demographic variables.
Further research is needed to disentangle the specific effects of fertility on population dynamics in these counties.