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Objective: Folate in breastmilk has important implications for offspring health and survival given the essential role of this vitamin in DNA synthesis, epigenetic functions, and amino acid metabolism. Yet, little is understood about the variation of folate in breastmilk and transfer across the postpartum year and beyond. Published studies tend to be limited to milk during days/weeks postpartum, and none applied an evolutionary perspective of parental investment. Methods: A secondary analysis of the data and specimens from 200 breastfeeding mothers within 1.5 years postpartum in food-insecure northern Kenya was conducted. ELISA determined folate-binding protein (FOLR1) in cryogenically archived breastmilk and maternal blood specimens, originally collected in 2006. Maternal folate was defined as blood serum FOLR1 multiplied by –1 because elevated FOLR1 is associated with folate deficiency. The concentration of milk FOLR1 was evaluated in relation to maternal folate and 1) infant sex (Trivers-Willard hypothesis), 2) time postpartum and parity (maternal residual reproductive value) using regression models adjusted for covariates. Results indicated: 1) no Trivers-Willard effect; 2) support for time postpartum but not for parity. Maternal folate and time postpartum inversely predicted milk FOLR1. There was an interaction between these variables (p<0.05). Maternal folate improved over time at a varying rate while milk FOLR1 decreased at a relatively steady rate. This inverse relationship became stronger as time advanced. Conclusion: The priority shift from the investment in current offspring toward maternal soma and potential future offspring in this study provides empirical support for the evolutionary hypothesis of parental investment and parent-offspring conflict. This study was funded by NSF (BCS #1638167), and the Wenner-Gren Foundation (Grant #9278). The original data/specimen collection was supported by NSF (BCS #0622358) and the Wenner-Gren Foundation (Grant #7460).
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A simple biochemical plasma test as an indicator of maternal energy balance predicts offspring survival in bighorn sheep
In species where offspring survival is highly variable relative to adult survival, such as bighorn sheep ( Ovis canadensis ), physiological indicators of maternal investment could clarify the functional mechanisms of life history trade-offs and serve as important predictors of population dynamics. From a management perspective, simple predictors of juvenile survival measured non-lethally from maternal samples could aid in identifying at-risk populations or individuals before significant mortality occurs. Blood biochemical parameters can offer low-cost insights into animal health and physiology, therefore we sought to develop a simple biochemical predictor of juvenile survival based on maternal blood samples. We measured biochemical indicators of energy balance in adult bighorn sheep at a single time point in January or February, and then monitored survival through August of the same year to assess how those measures related to survival of individual adults and their juvenile offspring. Juvenile survival was lower over the subsequent spring and summer when maternal adult serum beta-hydroxybutyric acid (β-HBA) concentration was high, indicating a negative energy balance in the mothers. However, serum β-HBA did not correlate with adult survival over the same period. Our findings suggest that even when maternal body condition is high, short-term caloric deficit may be sufficient trigger to decrease investment in offspring survival. This mechanism could protect adult females from investing heavily in juvenile survival when resources become too limited to support population growth. Our study suggests that β-HBA could be a powerful monitoring tool for bighorn sheep and other threatened ruminant populations under resource limitation.
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- Award ID(s):
- 1911994
- PAR ID:
- 10424909
- Date Published:
- Journal Name:
- Frontiers in Ecology and Evolution
- Volume:
- 11
- ISSN:
- 2296-701X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fevo.2023.1106635
