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Estradiol, reproductive cycle and preference behavior in a northern swordtail
Mary E Ramsey1, Ryan Y Wong, Molly E Cummings
1Section of Integrative Biology, University of Texas at Austin, TX 78712, USA. mramsey@mail.utexas.edu
General and Comparative Endocrinology
|October 28, 2010
Summary
Female fish reproductive state influences estradiol levels, but not mating preference or receptivity. Estradiol impacts locomotion and slightly influences preference, suggesting a dissociated reproductive system in Xiphophorus nigrensis.
Area of Science:
- Reproductive Biology
- Animal Behavior
- Endocrinology
Background:
- Estrogen is linked to female sexual behaviors, but its role in preference versus receptivity is unclear.
- Studying preference and receptivity separately is challenging due to their coupled expression.
- The live-bearing fish Xiphophorus nigrensis, with sperm storage, is a model for female mate choice evolution.
Purpose of the Study:
- To investigate the relationship between reproductive state, estradiol levels, and female behaviors (preference, receptivity, locomotion) in X. nigrensis.
- To determine if estradiol levels predict behavioral variations independently of the reproductive cycle.
- To explore the potential for a dissociated reproductive system in female fish.
Main Methods:
- Assayed estradiol and measured preference, receptivity, and locomotor behaviors in gestating X. nigrensis females.
- Re-tested females at multiple time points post-parturition (days 1, 7, 14, 21, 28).
- Assessed reproductive cycle status post-hoc to correlate with hormone levels and behaviors.
Main Results:
- Endogenous estradiol levels varied across the reproductive cycle, with lower levels in gestating females compared to those vitellogenesis/fertilizing.
- Receptivity and preference behaviors remained consistent throughout the reproductive cycle.
- Estradiol levels did not predict receptive behavior but were associated with increased locomotion; a slight negative correlation existed between estradiol and preference.
Conclusions:
- Female X. nigrensis exhibit consistent preference and receptivity behaviors irrespective of their reproductive cycle.
- Estradiol levels fluctuate with the reproductive cycle and influence locomotion and, to a lesser extent, preference.
- The findings suggest a facultatively dissociated reproductive system in X. nigrensis females, separating hormonal influences on different behavioral components.
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