Related Experiment Video
Updated: Mar 7, 2026
15:00
Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli
Published on: August 18, 2023
4.5K
Enchytraeus crypticus fitness: effect of density on a two-generation study
Micael F M Gonçalves1, Susana I L Gomes2, Amadeu M V M Soares1
1Department of Biology & CESAM, University of Aveiro, Aveiro, 3810-193, Portugal.
Ecotoxicology (London, England)
|February 25, 2017
Summary
Organism density significantly impacts reproduction and size in Enchytraeus crypticus. Higher densities led to fewer offspring and smaller individuals, with no carry-over effects to the next generation.
Area of Science:
- Ecotoxicology
- Soil ecology
- Invertebrate biology
Background:
- Organism density is a critical factor influencing physiological processes and fitness.
- Enchytraeus crypticus, an oligochaete, is a standard model organism in soil ecotoxicology.
- Understanding density-dependent effects is crucial for accurate ecotoxicological assessments.
Purpose of the Study:
- To investigate the influence of organism density on life-history parameters in Enchytraeus crypticus across two generations.
- To determine if density-related effects on reproduction and growth are transgenerational.
- To assess the implications of these findings for standard ecotoxicological tests.
Main Methods:
- Testing two densities (1 and 20 organisms per replicate) for the parental generation (F0).
- Testing two soil masses (10g and 20g) for the second generation (F1).
- Assessing reproductive output (juveniles per adult) and organism length as key endpoints.
Main Results:
- Reproductive output was significantly reduced at higher densities (N20) compared to lower densities (N1).
- Organisms in N1 produced three times more juveniles per adult than those in N20.
- Organism length was negatively affected by both density and limited space, with smaller individuals observed under crowded or confined conditions.
- No transgenerational effects were observed; parental generation density (F0) did not influence F1 reproduction or length.
Conclusions:
- Organism density is a significant factor affecting reproduction and growth in Enchytraeus crypticus.
- Density-dependent effects are primarily confined to the generation experiencing the density stress and do not transfer to the offspring.
- Findings highlight the importance of considering density in the design and interpretation of Enchytraeid Reproduction Tests, as adult mortality can skew results due to density-related changes.
Related Concept Videos
01:21Frequency-dependent Selection
24.4K
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
24.4K
02:27Background and Environment Affect Phenotype
7.9K
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
7.9K
01:26Derivatives: Problem Solving
133
Temperature-Dependent Growth of Brook TroutThe growth of brook trout is closely influenced by water temperature. Experimental data demonstrate how trout weight changes over a 24-day period in response to varying water temperatures. At lower temperatures, such as 15.5 degrees Celsius, brook trout show significant weight gain. However, as the temperature increases, the amount of weight gained steadily decreases. At the highest temperature measured, 24.4 degrees Celsius, trout experience a net...
133
01:11Testing a Claim about Mean: Known Population SD
3.3K
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...
3.3K
02:04Conservation of Small Populations
17.6K
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...
17.6K
02:29Hybrid Zones
22.2K
Hybrid zones are narrow regions where two closely related species interact, mate, and produce hybrids. Relative to either parent species, hybrids may possess distinct phenotypic or genetic differences that impact their survival and reproductive success. The genetic variances introduced by hybridization influence species diversity and speciation processes within the hybrid zone.
22.2K