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Factors Causing Seasonal Forms in Ascia monuste (Lepidoptera).
Science (New York, N.Y.)
|September 21, 1962
Summary
Environmental light influences seasonal color changes in Ascia monuste butterflies, with females showing distinct melanic (long-day) and white (short-day) forms. Genetic factors in Florida populations may determine the capacity for melanic coloration.
Area of Science:
- Entomology
- Environmental Biology
- Genetics
Background:
- Ascia monuste butterflies exhibit seasonal polyphenism, with distinct color morphs.
- Environmental factors, particularly light, are suspected to influence these seasonal changes.
- Previous research has not definitively identified all causative agents for this phenomenon.
Purpose of the Study:
- To investigate the role of light as a causative agent for seasonal forms in Ascia monuste.
- To determine if light is the sole factor responsible for seasonal polyphenism.
- To explore the genetic basis of melanic form capacity in Ascia monuste populations.
Main Methods:
- Controlled experiments exposing Ascia monuste to varying light durations (long-day vs. short-day).
- Observation and documentation of resulting adult female phenotypes (coloration).
- Comparative analysis of melanic form frequency across different geographic populations, focusing on Florida.
Main Results:
- Light exposure demonstrably influences the seasonal forms of Ascia monuste.
- The long-day photoperiod results in a melanic phenotype, while the short-day photoperiod yields a white phenotype.
- These light-induced effects are exclusively observed in female butterflies.
- The predisposition to develop the melanic form is most prevalent in the Florida Ascia monuste population, suggesting a genetic component.
Conclusions:
- Photoperiodic light is a significant environmental cue inducing seasonal polyphenism in Ascia monuste females.
- While light is a key factor, other unproven agents may also contribute to seasonal form determination.
- Genetic variation, particularly within the Florida population, likely underlies the differential capacity for expressing the melanic phenotype.
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