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Increased Reproductive Output and Telomere Shortening Following Calcium Supplementation in a Wild Songbird
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  • Marina Rodriguez,
  • Susan Bailey,
  • Paul Doherty,
  • Kathryn Huyvaert
Marina Rodriguez
Colorado State University

Corresponding Author:mdrod@rams.colostate.edu

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Susan Bailey
Colorado State University
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Paul Doherty
Colorado State University
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Kathryn Huyvaert
Washington State University
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Abstract

Life history theory predicts increased parental investment comes with fitness costs, often expressed as negative effects on survival and future reproduction. Though annual telomere shortening has been shown to increase with higher reproductive output, we use calcium supplementation as a novel approach to experimentally alter overall reproductive investment and measure telomere shortening exclusively linked to the breeding season. Calcium is a nutrient critical to avian reproduction as the intake of natural calcium is needed for egg production, embryo development, and nestling growth. Altering the amount of calcium availability during the breeding season allows us to examine the individual biological response to the experimental modification of reproduction, and allows us to account for the reproductive costs associated with egg production and laying of the entire clutch. We used calcium supplementation in nesting Tachycineta bicolor (tree swallow) and measured telomere length before and after breeding to better understand the costs of reproduction and life history trade-offs. Measuring telomere length at the beginning and end of each breeding season facilitated evaluation of telomere shortening occurring only during the breeding period of this species. We found that mothers supplemented with calcium had higher reproductive success and greater telomere shortening, though their offspring had longer telomeres at 12 days old. Here we show tree swallow mothers supplemented with calcium had higher reproductive output and offspring with longer telomeres, yet these mothers suffered the cost of shorter expected lifespan, as indicated by relatively more shortening of their telomeres during the reproductive season. Our results provide clear support for previous work on trade-offs between reproduction and longevity and challenge previous calcium supplementation studies that suggest excess calcium reduces the cost of reproduction thereby improving fitness in calcium supplemented parents.
30 Jan 2024Submitted to Ecology and Evolution
01 Feb 2024Submission Checks Completed
01 Feb 2024Assigned to Editor
23 Feb 2024Review(s) Completed, Editorial Evaluation Pending
12 Mar 2024Editorial Decision: Revise Minor
11 Jun 20241st Revision Received
11 Jun 2024Review(s) Completed, Editorial Evaluation Pending
12 Jun 2024Reviewer(s) Assigned
22 Jul 2024Editorial Decision: Revise Minor
20 Sep 20242nd Revision Received
21 Sep 2024Submission Checks Completed
21 Sep 2024Assigned to Editor
21 Sep 2024Review(s) Completed, Editorial Evaluation Pending
30 Sep 2024Editorial Decision: Accept