Related Experiment Video
Updated: Jun 5, 2026
06:49
Volatile Sex Pheromone Extraction and Chemoattraction Assay in Caenorhabditis elegans
Published on: August 9, 2024
Sex in an Evolutionary Perspective: Just Another Reaction Norm
Evolutionary Biology
|December 21, 2010
Summary
Biological sex and associated traits are not static but are phenotypically plastic. This evolutionary perspective reveals significant variability in sex determination, roles, and sexual dimorphism, challenging discrete classifications.
Area of Science:
- Evolutionary Biology
- Developmental Biology
- Genetics
Background:
- Commonly, sex differences are viewed as biologically inevitable and static.
- Sexual selection theory often reinforces a deterministic view of sex and traits.
- This perspective does not fully align with evolutionary theory on sex determination and sexual dimorphism.
Purpose of the Study:
- To challenge the notion of static biological sex and sex-associated traits.
- To explore sex as a reaction norm with phenotypic plasticity.
- To review evolutionary changes in sex, sex determination, and sex roles.
Main Methods:
- Review of recent findings in sex determination mechanisms.
- Analysis of empirical data on morphology and behavior.
- Integration of genetic and developmental models.
Main Results:
- Sex determination is fundamentally plastic, even when genetically influenced.
- Phenotypic expression of sex-associated traits always includes a plastic component.
- Evolutionary changes in sex, sex determination, and sex roles are extremely variable.
Conclusions:
- Sexual differences are not expected to be discrete or pre-determined.
- Viewing sex as a reaction norm highlights significant plasticity and overlap between sexes.
- Acknowledging this variability is crucial for objective evolutionary research.
Related Concept Videos
01:23Criticisms of the Evolutionary Perspective
In a study where individuals posing as strangers offered compliments and proposed casual sex to students, the responses differed significantly based on gender. Not a single woman accepted the proposal, while 70% of the men agreed. This outcome provides a useful scenario to explore through the lens of evolutionary psychology and social learning theory, highlighting the diverse perspectives on human sexual behaviors.
Evolutionary psychology provides one explanation for these findings, suggesting...
Evolutionary psychology provides one explanation for these findings, suggesting...
01:06Natural Selection and Mating Preferences
The principle of natural selection posits that organisms better adapted to their environment are more likely to survive and reproduce. This principle is closely intertwined with mating preferences, a key aspect of sexual selection, which evolutionary psychologists believe is driven by instincts to propagate one's genes. Such instincts significantly influence mating behaviors and preferences between genders.
Females, due to their biological roles in conception, pregnancy, and nursing, inherently...
Females, due to their biological roles in conception, pregnancy, and nursing, inherently...
01:20Evolutionary Psychology
Evolutionary psychology explores the origins of human behavior and mental processes by framing them within the context of natural selection, a theory famously propounded by Charles Darwin. This field asserts that many behaviors common across human societies — ranging from instinctive fear reactions to complex social interactions — arose as evolutionary adaptations. These adaptations enhanced the survival and reproductive success of our ancestors, thereby becoming embedded in the human psyche...
01:20Mate Choice
Mate choice—the decision about whom to mate with—is a type of natural selection, since animals must reproduce to pass down their genes. Mate choice is also called intersexual selection because the behavior occurs between the sexes.
02:45The Ratio of X Chromosome to Autosomes
In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
02:27Background and Environment Affect Phenotype
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...