Vastly Differing Circadian Rhythms of the Spiders Cyrtophora citricola and Allocyclosa bifurca Suggest Short Clocks Pair with Diurnal Crypsis

Authors' Affiliations

Jessica Upham, Department of Biological Sciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN Thomas Jones, Department of Biological Sciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN Darrell Moore, Department of Biological Sciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN

Location

Culp Center Ballroom

Start Date

4-25-2023 9:00 AM

End Date

4-25-2023 11:00 AM

Poster Number

126

Faculty Sponsor’s Department

Biological Sciences

Name of Project's Faculty Sponsor

Thomas Jones

Additional Sponsors

Darrell Moore

Classification of First Author

Undergraduate Student

Competition Type

Competitive

Type

Poster Presentation

Project's Category

Circadian Rhythms

Abstract or Artist's Statement

Circadian rhythms are outputs of the internal clock that regulates the daily functions of almost all living organisms. Circadian rhythms are typically 24 hours because they are synchronized by external cues such as the natural light/dark cycles of the environment. When external cues are removed, the circadian rhythm “free-runs,” thus revealing the organism’s endogenous circadian period. Recent studies have found that the trashline orbweaving spiders Cyclosa turbinata and Allocyclosa bifurca have abnormally short circadian rhythms of approximately 19 and 18 hours, respectively. Trashline orbweavers construct a line of debris made of prey carcasses in the center of their web and then remain undetectable by being cryptic within their trashline. Despite similar circadian rhythms and web-building behaviors, recent genetic findings indicate that these species actually are not closely related. In fact, both genetic and morphological data now suggest A. bifurca is more closely related to Cyrtophora citricola, the Tropical Tent-web spider. This would suggest that trashline behavior and exceptionally short circadian clocks evolved independently in C. turbinataand A. bifurca. This study analyzed the circadian rhythm of C. citricola and compared it to the circadian rhythm of A. bifurca. If C. citricola has an abnormally short clock like A. bifurca, this would indicate that the evolution of the short clock preceded the divergence of these species’ lineages. However, if C. citricola has a more typical clock, this would suggest that the unusually short clock evolved in the A. bifurca lineage and may be more ecologically linked to the trashline behavior. Thirty-two female C. citricola were collected in Southern Florida and had their locomotor activity measured over four days of 12:12 light/dark cycles followed by complete darkness to determine their circadian free-running periods (FRP). Cyrtophora citricola was found to have a more typical FRP of 24.0 + 0.43 hours. Despite being closely related, C. citricola and A. bifurca differ significantly in their circadian rhythms, suggesting that short circadian rhythms may be ecologically linked with trashline behavior.

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Apr 25th, 9:00 AM Apr 25th, 11:00 AM

Vastly Differing Circadian Rhythms of the Spiders Cyrtophora citricola and Allocyclosa bifurca Suggest Short Clocks Pair with Diurnal Crypsis

Culp Center Ballroom

Circadian rhythms are outputs of the internal clock that regulates the daily functions of almost all living organisms. Circadian rhythms are typically 24 hours because they are synchronized by external cues such as the natural light/dark cycles of the environment. When external cues are removed, the circadian rhythm “free-runs,” thus revealing the organism’s endogenous circadian period. Recent studies have found that the trashline orbweaving spiders Cyclosa turbinata and Allocyclosa bifurca have abnormally short circadian rhythms of approximately 19 and 18 hours, respectively. Trashline orbweavers construct a line of debris made of prey carcasses in the center of their web and then remain undetectable by being cryptic within their trashline. Despite similar circadian rhythms and web-building behaviors, recent genetic findings indicate that these species actually are not closely related. In fact, both genetic and morphological data now suggest A. bifurca is more closely related to Cyrtophora citricola, the Tropical Tent-web spider. This would suggest that trashline behavior and exceptionally short circadian clocks evolved independently in C. turbinataand A. bifurca. This study analyzed the circadian rhythm of C. citricola and compared it to the circadian rhythm of A. bifurca. If C. citricola has an abnormally short clock like A. bifurca, this would indicate that the evolution of the short clock preceded the divergence of these species’ lineages. However, if C. citricola has a more typical clock, this would suggest that the unusually short clock evolved in the A. bifurca lineage and may be more ecologically linked to the trashline behavior. Thirty-two female C. citricola were collected in Southern Florida and had their locomotor activity measured over four days of 12:12 light/dark cycles followed by complete darkness to determine their circadian free-running periods (FRP). Cyrtophora citricola was found to have a more typical FRP of 24.0 + 0.43 hours. Despite being closely related, C. citricola and A. bifurca differ significantly in their circadian rhythms, suggesting that short circadian rhythms may be ecologically linked with trashline behavior.