Evidence for an Allee effect in a declining fur seal population
Rebecca Nagel1, Claire Stainfield2, Cameron Fox-Clarke2
1Department of Animal Behaviour, Bielefeld University, 33501 Bielefeld, Germany.
Proceedings. Biological Sciences
|March 24, 2021
Summary
Allee effects may threaten Antarctic fur seals, with low-density colonies experiencing higher pup mortality due to predation. This challenges previous assumptions about population dynamics in declining species.
Area of Science:
- Ecology
- Population Dynamics
- Conservation Biology
Background:
- Allee effects, where population growth rate decreases at low densities, are crucial for extinction risk.
- Evidence for Allee effects in wild populations remains debated.
- Antarctic fur seals (Arctocephalus gazella) face population declines linked to climate change and reduced food availability.
Purpose of the Study:
- To investigate Allee effects in Antarctic fur seals using colonies of contrasting densities.
- To assess how population density influences pup mortality and body condition.
- To understand the role of predation in declining pinniped populations.
Main Methods:
- Utilized a natural experiment with two adjacent Antarctic fur seal colonies of different densities.
- Collected biometric time-series data from 25 pups per colony over two breeding seasons.
- Analyzed pup mortality rates, causes of death (trauma, starvation, predation), and pup body condition in relation to colony density.
Main Results:
- Contrary to previous findings, higher pup mortality occurred at low densities.
- Predation emerged as the primary cause of death in low-density colonies.
- Pup body condition was poorer in low-density colonies, especially during a poor food availability season.
Conclusions:
- Findings suggest Allee effects are present in this Antarctic fur seal population.
- Predation may play an increasing role in the decline of this species at low densities.
- This research provides critical insights into population dynamics and conservation challenges for Antarctic fur seals.
Related Concept Videos
02:07Conservation of Declining Populations
12.0K
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.
12.0K
02:04Conservation of Small Populations
16.0K
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...
16.0K
01:32What is Natural Selection?
122.8K
Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become more common within a population or species. Naturally selected traits initially arise via random genetic mutations. In order for selection to occur, there must be variation within a population, the trait controlling the variation must be heritable, and there must be an evolutionary advantage for variation in the trait.
122.8K
02:55The Evidence for Evolution
45.6K
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.
45.6K
00:48Optimal Foraging
12.8K
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
12.8K
01:39Keystone Species
22.8K
Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ecological community’s structure. Many factors affect community structure, including abiotic factors (e.g., sunlight and nutrients), disturbances (e.g., fire or flood), species interactions (e.g., predation or competition), and chance events (e.g., foreign species invasion). Certain species—such as keystone species—also play a...
22.8K