DOI: 10.5061/dryad.n02v6wx3v
title: Data from: Timing of conceptions in Phayre's leaf monkeys: energy and phytochemical intake

description: Raising offspring imposes energetic costs, especially for female mammals.
 Consequently, seasons favoring high energy intake and sustained positive
 energy balance often result in a conception peak. Factors that may weaken
 this coordinated effect include premature offspring loss and adolescent
 subfertility. Furthermore, seasonal ingestion of phytochemicals may
 facilitate conception peaks. We examined these factors and potential
 benefits of a conception peak (infant survival, interbirth interval) in
 Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus). Data were
 collected at Phu Khieo Wildlife Sanctuary, Thailand (78 conceptions). We
 estimated periods of high energy intake based on fruit and young leaf
 feeding and via monthly energy intake rates. Phytochemical intake was
 based on fecal progestin. We examined seasonality (circular statistics,
 cox proportional hazard models) and compared consequences of timing
 (infant survival and interbirth intervals, t-test, Fisher exact test).
 Conceptions occurred in all months but peaked from May to August. This
 peak coincided with high fecal progestin rather than presumed positive
 energy balance. Primipara conceived significantly later than multipara.
 Neither infant survival nor interbirth intervals were related to the
 timing of conception. Periods of high energy intake may not exist and
 would not explain the conception peak in this population. However, the
 presumed high intake of phytochemicals was tightly linked to the
 conception peak. Timing conceptions to the peak season did not provide
 benefits, suggesting that the clustering of conceptions may be a mere
 by-product of phytochemical intake. To confirm this conclusion, seasonal
 changes in phytochemical intake and hormone levels need to be studied more
 directly.
description: The data were observational in
 nature. Of the 78 total conceptions used in the analyses, 71 were based on
 the day of detection of a newborn in the study groups from which the mean
 gestation length (205 days) was subtracted to find the conception date.
 The 7 additional conceptions were determined via hormone analysis of fecal
 material (Lu, Borries, Czekala & Beehner, 2010). Lu, A.,
 Borries, C., Czekala, N. M., & Beehner, J. C. (2010). Reproductive
 characteristics of wild female Phayre's leaf monkeys.
 <em>American Journal of Primatology</em>,
 <strong>72</strong>, 1073-1081. https://doi.org/10.1002/ajp.20866.
description: READ ME The information compiled here is part of: Borries, Lu, Ossi-Lupo,
 Koenig (202x). Data from: Timing of conceptions in Phayre’s leaf monkeys:
 energy and phytochemical intake [Dataset]. Dryad.
 https://doi.org/10.5061/dryad.n02v6wx3v which is related to an accepted
 manuscript in American Journal of Biological Anthropology, (Borries, Lu,
 Ossi-Lupo & Koenig, AJPA-2023-00136.R1) The data were
 observational in nature. Of the 78 total conceptions used in the analyses,
 71 were based on the day of detection of a newborn in the study groups
 from which the mean gestation length (205 days) was subtracted to find the
 conception date. The 7 additional conceptions were determined via hormone
 analysis of fecal material (Lu, Borries, Czekala & Beehner, 2010).
 Due to a few gaps in observations, not all births were known to the day
 and were estimated based on the state of infant development as well as
 skin and coat color at the time of detection. Phayre’s leaf monkeys are
 born with a pale pinkish skin and a bright orange fur which changes
 gradually and predictably to the adult grey color over the course of
 several months, thus facilitating age estimates of small infants (Borries,
 Larney, Lu, Ossi & Koenig, 2008; Larney, 2013). File
 ‘all\_conceptions’ This file lists all 78 conceptions included in the
 analysis with each row representing one conception. They refer to 39
 females from 4 study groups during 21 complete group years between July
 2001 and June 2008. From left to right, the columns contain: ‘parity’ of
 the female, coded as * multiparous = adult female known to have had at
 least one prior offspring. * primiparous = the first conception of a
 nulliparous female. * unknown = female could be primiparous or
 multiparous. ‘current\_offspring’ of the female, coded as: * dead = female
 had an offspring which had died or disappeared by the time of this next
 listed conception. * living = female has a living offspring at the time of
 this next listed conception. * none = primiparous female, has not yet
 given birth for the first time and has no offspring. * unknown = female
 was not yet known at the time of conception but was known when she gave
 birth so that the conception date could be calculated.
 ‘group\_of\_residency’ of the female, coded as: * same = the conception
 listed here took place in the same group as the previous one (when the
 current offspring was conceived), i.e., no dispersal took place between
 these 2 conceptions. * new = female dispersed into another group between
 conceptions. * unknown = female residency unknown at the time of
 conception but known when she gave birth. * irrelevant = primiparous
 females have no prior conception for comparison. Per definition, they
 conceive for the first time in their life. ‘conception\_day’ provides the
 conception day of the month to illustrate how the
 ‘conception\_day\_of\_the\_year’ was found. ‘conception\_month’ provides
 the conception month to illustrate how the
 ‘conception\_day\_of\_the\_year’ was found and to facilitate plotting of
 the data. ‘conception\_day\_of\_year’ provides the conception dates in
 day-of-the-year format (considering the respective (leap) year) for
 testing of seasonal effects and between subsamples.
 ‘conception\_known\_or\_calculated’ coded as * calculated = the conception
 date was found by subtracting 205 days (the mean gestation length, Lu et
 al., 2010) from the date of parturition. * known = the conception date was
 determined based on changes in hormone levels extracted from fecal samples
 (Lu et al., 2010). File ‘re\_conceptions’ The file provides information on
 the period leading up to re-conceptions by listing presumed conditions
 regarding high fecal progestin concentrations and positive energy balance
 for the respective time period. The data refer only to multiparous females
 with a living offspring at the time of re-conception and excludes females
 who dispersed into another group. The listing begins with the seventh
 month after parturition (third column) for each individual female (first
 column) / infant (second column) combination because the earliest
 re-conception in the population occurred in month 8 postpartum. Each month
 is characterized (1/0) as * high fP period, i.e., consecutive months when
 fecal progestin metabolite concentrations were significantly elevated. It
 is assumed that this effect is related to the intake of leaves and fruits
 from Vitex trees (Lu et al., 2011). Each year the high fP period was set
 to begin one month after the onset of the respective wet season (when at
 least 50 mm of rain fell per month, Walter, 1990) and to last until
 September inclusively. * high energy period, i.e., consecutive months
 which begin after the energy balance is assumed to have been positive for
 at least three months. Based on data from a complete year (Suarez, 2013)
 fruit feeding increased 3 months after the onset of the wet season.
 Therefore, the beginning of increased fruit feeding (i.e., a positive
 energy balance) in other years was determined relative to the wet season.
 After 3 consecutive months of positive energy balance, the high energy
 period begins. It is estimated to last until December inclusively each
 year. Depending on the respective year (variable onset of the wet season),
 the high energy period is estimated to last either 3 or 4 months. *
 re-conception, the month when the female conceived again was indicated as
 ’1’ and thereafter the female is removed from the sample for this
 re-conception. Females and infants are anonymized as numbers, but females
 contributing more than once to the dataset are identified by the same
 number. Consecutive offspring numbers for an individual female do not
 necessarily represent the birth order, because offspring who died prior to
 re-conception were not included here. Relationship between the two
 datasets The data compiled in the file named ‘re\_conceptions’ are a
 subsample of the data compiled in the file named ‘all\_conceptions’. Only
 re-conceptions in multiparous females with a living offspring at the time
 of re-conception were considered (28 cases for 17 females) in the file
 ‘re\_conceptions’. For these 28 cases, additional information is provided
 in the file ‘re\_conceptions’ beginning with month 7 after parturition. We
 excluded 22 additional conceptions because the multiparous female had not
 conceived again when the study ended (some females disappeared, others
 dispersed, or the last parturition took place very late in the study).
 File ‘interbirth\_intervals’ Interbirth intervals [in months] for
 multiparous females with a living offspring at the time of re-conception
 are listed in relation to when the conception occurred (peak versus
 off-peak, details below). There is no direct relationship to the data in
 the other two files. From left to right, the columns contain:
 ‘peak\_versus\_off\_peak’ * peak = the conception leading to the birth of
 the first infant of the interbirth interval occurred during the conception
 peak from May to August * off-peak = the conception leading to the birth
 of the first infant of the interbirth interval occurred during off-peak
 from September to April. ‘interbirth\_interval’ * Holds the numeric value
 of each interbirth interval [in months] that began with the respective
 conception. References Borries, C., Larney, E., Lu, A., Ossi, K.,
 & Koenig, A. (2008). Costs of group size: lower developmental and
 reproductive rates in larger groups of leaf monkeys. Behavioral Ecology,
 19, 1186-1191. https://doi.org/10.1093/beheco/arn088. Borries, C., Lu, A.,
 Ossi-Lupo, K., & Koenig, A. (in revision). Timing of conceptions
 in Phayre's leaf monkeys: energy and phytochemical intake. American
 Journal of Biological Anthropology. Larney, E. (2013). The influence of
 genetic and social structure on reproduction in Phayre's leaf monkeys
 (Trachypithecus phayrei crepusculus) dissertation thesis. Stony Brook
 University, Stony Brook. Lu, A., Beehner, J. C., Czekala, N. M., Koenig,
 A., Larney, E., & Borries, C. (2011). Phytochemicals and
 reproductive function in wild female Phayre's leaf monkeys
 (Trachypithecus phayrei crepusculus). Hormones and Behavior, 59, 28-36.
 https://doi.org/10.1016/j.yhbeh.2010.09.012. Lu, A., Borries, C., Czekala,
 N. M., & Beehner, J. C. (2010). Reproductive characteristics of
 wild female Phayre's leaf monkeys. American Journal of Primatology,
 72, 1073-1081. https://doi.org/10.1002/ajp.20866. Suarez, S. A. (2013).
 Diet of Phayre's leaf-monkey in the Phu Khieo Wildlife Sanctuary,
 Thailand. Asian Primates Journal, 3, 2-12. Walter, H. (1990). Vegetation
 und Klimazonen. Stuttgart: Eugen Ulmer.