Related Experiment Video
Updated: Jun 15, 2026
07:37
Resurrection of Dormant Daphnia magna: Protocol and Applications
Published on: January 19, 2018
Differences in estimates of extinction risk between occupancy and abundance data.
Mattia Falaschi1, Elia Lo Parrino1, Raoul Manenti1
1Department of Environmental Science and Policy, Università degli Studi di Milano, Milan, Italy.
Summary
Comparing population trends using presence-absence and abundance data reveals differences in assessing extinction risk. Abundance data indicates faster declines but higher uncertainty, while occupancy data offers more robust, albeit slower, trend estimates for conservation status.
Area of Science:
- Conservation biology
- Population ecology
- Wildlife management
Background:
- Population trends are crucial for conservation status assessment.
- Presence-absence (occupancy) and abundance data are common but differ in sensitivity.
- Quantitative comparisons of threat status using these data types are limited.
Purpose of the Study:
- To quantitatively compare threat status assessments for amphibians using occupancy versus abundance data.
- To evaluate the consistency of International Union for Conservation of Nature (IUCN) criteria application with different data types.
- To determine which data type provides more robust and timely estimates of population declines.
Main Methods:
- Applied IUCN criteria to 25 years of amphibian population data.
- Developed and compared occupancy and abundance models.
- Assessed extinction risk and population decline rates using both data types.
Main Results:
- Both occupancy and abundance data indicated population declines.
- Abundance data revealed faster declines and higher IUCN threat categories but with greater uncertainty.
- Occupancy data showed smaller proportional changes but provided more robust estimates.
Conclusions:
- Occupancy and abundance data yield different insights into population trends and threat status.
- Abundance data detects declines earlier, while occupancy data offers greater reliability.
- Integrating multiple measures of population decline is recommended for accurate conservation status assessment.
Related Concept Videos
00:30What are Populations and Communities?
Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting populations of different species. Metapopulations span multiple populations of the same species that occupy different areas. Metapopulations interact through immigration and emigration, providing genetic diversity that lends resilience to harsh environments. Population size and density can be estimated using quadrat and mark and recapture...
01:50Threats 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...
02:04Conservation 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...
02:07Conservation 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.
02:31Habitat Fragmentation
Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land conversion, as well as slower geological processes leading to changes in the physical environment, are the two leading causes of habitat fragmentation. The fragmentation process typically follows the same steps: perforation, dissection, fragmentation, shrinkage, and attrition.
01:11Testing a Claim about Mean: Known Population SD
A complete procedure of testing the hypothesis about a population mean is explained here.
Estimating a population mean requires the samples to be distributed normally. The data should be collected from the randomly selected samples having no sampling bias. The sample size needed to be higher than 30, and most importantly, the population standard deviation should be already known.
In most realistic situations, the population standard deviation is often unknown, but in rare circumstances, when it...
Estimating a population mean requires the samples to be distributed normally. The data should be collected from the randomly selected samples having no sampling bias. The sample size needed to be higher than 30, and most importantly, the population standard deviation should be already known.
In most realistic situations, the population standard deviation is often unknown, but in rare circumstances, when it...