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Biological and environmental influences on parturition date and birth mass of a seasonal breeder.

Wolcott DM, Reitz RL, Weckerly FW - PLoS ONE (2015)

Bottom Line: Random effects revealed considerable variation among mothers and years.This study demonstrates that, in long-lived polytocous species, environmental factors may have a greater influence on natal features than previously supposed and the influence from biological factors is also complex.The documented responses to environmental influences provide unique insights into how mammalian seasonal reproductive dynamics may respond to current changes in climate.

View Article: PubMed Central - PubMed

Affiliation: Texas State University, Department of Biology, San Marcos, Texas, United States of America.

ABSTRACT
Natal features (e.g. Julian birth date and birth mass) often have fitness consequences and can be influenced by endogenous responses by the mother to seasonal fluctuations in nutritional quality and photoperiodic cues. We sought to further understand the biological and environmental factors that influence the natal features of a polytocous species in an environment with constant nutritional resources and limited seasonal variation. During a 36-year study we assessed the influence of biological factors (maternal age and litter type [i.e., litter size and sexual composition]) and environmental factors (total precipitation and mean maximum temperature during months encompassing conception, the last trimester of gestation, and the entire length of gestation) on Julian birth date and birth mass using linear-mixed effects models. Linear and quadratic functions of maternal age influenced both natal features with earliest Julian birth dates and heaviest birth masses occurring at prime-age and older individuals, which ranged from 5-9 years of age. Litter type influenced Julian birth date and birth mass. Interestingly, environmental factors affected Julian birth date and birth mass even though mothers were continuously allowed access to a high-quality diet. Random effects revealed considerable variation among mothers and years. This study demonstrates that, in long-lived polytocous species, environmental factors may have a greater influence on natal features than previously supposed and the influence from biological factors is also complex. The documented responses to environmental influences provide unique insights into how mammalian seasonal reproductive dynamics may respond to current changes in climate.

No MeSH data available.


Related in: MedlinePlus

Walter climate diagram derived from a weather station in Kerrville, TX, USA from 1977–2012.The solid line represents the average total precipitation (mm) and the dashed line represents the average mean temperature for each month.
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pone.0124431.g001: Walter climate diagram derived from a weather station in Kerrville, TX, USA from 1977–2012.The solid line represents the average total precipitation (mm) and the dashed line represents the average mean temperature for each month.

Mentions: Environmental factors were collated from a weather station in Kerrville, TX, USA (30° 4.0’ N, 99° 7.0’ W), which was located approximately 38 km from the pens. Precipitation variables consisted of monthly total precipitation during periods deemed important to conception and parturition of neonates (October–December and April–June). We included two additional predictor variables by summing the monthly total precipitation from October–June (prior to conception and throughout gestation) and April–June (encompassing the months surrounding the last trimester of gestation). Months encompassing the last trimester of gestation were deemed important because most fetal growth occurs during this period [38]. Predictor variables for mean maximum temperature were calculated similarly to those of total precipitation. Mean maximum temperature was recorded for the individual months of October–December and April–June, and was also averaged between the months of October–June and April–June. Mean maximum temperature was used because it can affect activity patterns and rumination time in ungulates [39,40]. Average annual precipitation at the pens, during the study, was 802.9 mm (min = 333.1 mm, max = 1298.7 mm, SE = 38.5 mm, CV = 0.30) with most precipitation occurring from May–June (average = 195.0 mm) and September–October (average = 180.8 mm, Fig 1). Winters were mild, with mean minimum temperatures in January of 0.6°C, and summers were hot with mean maximum temperatures in August of 34.2°C.


Biological and environmental influences on parturition date and birth mass of a seasonal breeder.

Wolcott DM, Reitz RL, Weckerly FW - PLoS ONE (2015)

Walter climate diagram derived from a weather station in Kerrville, TX, USA from 1977–2012.The solid line represents the average total precipitation (mm) and the dashed line represents the average mean temperature for each month.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401666&req=5

pone.0124431.g001: Walter climate diagram derived from a weather station in Kerrville, TX, USA from 1977–2012.The solid line represents the average total precipitation (mm) and the dashed line represents the average mean temperature for each month.
Mentions: Environmental factors were collated from a weather station in Kerrville, TX, USA (30° 4.0’ N, 99° 7.0’ W), which was located approximately 38 km from the pens. Precipitation variables consisted of monthly total precipitation during periods deemed important to conception and parturition of neonates (October–December and April–June). We included two additional predictor variables by summing the monthly total precipitation from October–June (prior to conception and throughout gestation) and April–June (encompassing the months surrounding the last trimester of gestation). Months encompassing the last trimester of gestation were deemed important because most fetal growth occurs during this period [38]. Predictor variables for mean maximum temperature were calculated similarly to those of total precipitation. Mean maximum temperature was recorded for the individual months of October–December and April–June, and was also averaged between the months of October–June and April–June. Mean maximum temperature was used because it can affect activity patterns and rumination time in ungulates [39,40]. Average annual precipitation at the pens, during the study, was 802.9 mm (min = 333.1 mm, max = 1298.7 mm, SE = 38.5 mm, CV = 0.30) with most precipitation occurring from May–June (average = 195.0 mm) and September–October (average = 180.8 mm, Fig 1). Winters were mild, with mean minimum temperatures in January of 0.6°C, and summers were hot with mean maximum temperatures in August of 34.2°C.

Bottom Line: Random effects revealed considerable variation among mothers and years.This study demonstrates that, in long-lived polytocous species, environmental factors may have a greater influence on natal features than previously supposed and the influence from biological factors is also complex.The documented responses to environmental influences provide unique insights into how mammalian seasonal reproductive dynamics may respond to current changes in climate.

View Article: PubMed Central - PubMed

Affiliation: Texas State University, Department of Biology, San Marcos, Texas, United States of America.

ABSTRACT
Natal features (e.g. Julian birth date and birth mass) often have fitness consequences and can be influenced by endogenous responses by the mother to seasonal fluctuations in nutritional quality and photoperiodic cues. We sought to further understand the biological and environmental factors that influence the natal features of a polytocous species in an environment with constant nutritional resources and limited seasonal variation. During a 36-year study we assessed the influence of biological factors (maternal age and litter type [i.e., litter size and sexual composition]) and environmental factors (total precipitation and mean maximum temperature during months encompassing conception, the last trimester of gestation, and the entire length of gestation) on Julian birth date and birth mass using linear-mixed effects models. Linear and quadratic functions of maternal age influenced both natal features with earliest Julian birth dates and heaviest birth masses occurring at prime-age and older individuals, which ranged from 5-9 years of age. Litter type influenced Julian birth date and birth mass. Interestingly, environmental factors affected Julian birth date and birth mass even though mothers were continuously allowed access to a high-quality diet. Random effects revealed considerable variation among mothers and years. This study demonstrates that, in long-lived polytocous species, environmental factors may have a greater influence on natal features than previously supposed and the influence from biological factors is also complex. The documented responses to environmental influences provide unique insights into how mammalian seasonal reproductive dynamics may respond to current changes in climate.

No MeSH data available.


Related in: MedlinePlus