Related Experiment Video
Updated: May 15, 2026
08:03
Methods for Staging Pupal Periods and Measurement of Wing Pigmentation of Drosophila guttifera
Published on: January 24, 2018
Drosophila mutants suggest a strong drive toward complexity in evolution
Leonore Fleming1, Daniel W McShea
1Department of Philosophy, Duke University, Box 90743, Durham, NC 27708, USA. leonore.fleming@duke.edu
Evolution & Development
|January 22, 2013
Summary
Evolutionary biology suggests complexity increases over time. Laboratory experiments on Drosophila melanogaster mutants support the Zero Force Evolutionary Law (ZFEL), indicating complexity rises when evolutionary pressures are low.
Area of Science:
- Evolutionary biology
- Developmental biology
- Genetics
Background:
- The increase of complexity during evolution is widely accepted, but its underlying causes remain unclear.
- The Zero Force Evolutionary Law (ZFEL) proposes a natural tendency towards increased complexity in the absence of strong selective pressures or constraints.
- Heritable variation accumulation drives complexity when evolutionary opposition is minimal.
Purpose of the Study:
- To investigate the Zero Force Evolutionary Law (ZFEL) hypothesis.
- To evaluate the morphological complexity of laboratory-generated mutants in Drosophila melanogaster.
- To determine if reduced selective forces lead to increased organismal complexity.
Main Methods:
- Assessed gross morphological complexity in Drosophila melanogaster mutants.
- Measured complexity across part types, shape, and color at two focal levels.
- Compared complexity of mutants to wild-type organisms.
- Analyzed complexity based on the degree of constraint on different organismal parts.
Main Results:
- Drosophila melanogaster mutants exhibited significantly greater morphological complexity compared to wild-type.
- Weakly constrained parts in mutants showed significantly higher complexity than more constrained parts.
- Findings provide empirical support for the ZFEL hypothesis.
Conclusions:
- The study supports the Zero Force Evolutionary Law (ZFEL) as a driver of evolutionary complexity.
- Reduced selective forces in laboratory mutants correlate with increased morphological complexity.
- These results offer a foundation for further empirical research into the ZFEL's applicability and scope.
Related Concept Videos
01:24Evolution of New Traits in Microbes
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
02:55The Evidence for Evolution
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.
02:46Genetic Screens
Genetic screens are tools used to identify genes and mutations responsible for phenotypes of interest. Genetic screens help identify individuals or a group of people at risk of developing genetic diseases and help them with early intervention, targeted therapy, and reproductive options.
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...