Thorley, JackClutton-Brock, Tim H.Spence-Jones, Helen C.Turner, ZoeSharp, Stuart P.Manser, Marta B.Boner, WinnieGillespie, RobertCram, Dominic L.2026-03-112026-03-112026-02Thorley J., Clutton-Brock T., Spence-Jones H.C. et al. 2026, 'The ecology of gestational growth in a wild cooperative mammal', Journal of Animal Ecology, vol. 95, no. 2, pp. 257-269, doi : 10.1111/1365-2656.70199.0021-8790 (print)1365-2656 (online)10.1111/1365-2656.70199http://hdl.handle.net/2263/108896DATA AVAILABILITY STATEMENT : Data and reproducible R code are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.j6q573nv5 (Thorley et al., 2025). SUPPORTING INFORMATION FIGURE S1. The distribution of inter-birth intervals (IBI) in meerkats. FIGURE S2. The strong positive associations between conception mass and post-birth mass in meerkats. FIGURE S3. The data distribution for the maternal and social covariates, and the correlations among them, in pregnant meerkats. FIGURE S4. Estimating body condition at the start of each pregnancy in wild meerkats. FIGURE S5. The average body condition of all known-age meerkats from 1998 to 2022. FIGURE S6. Time series of the weekly mean maximum and minimum temperature, weekly total rainfall, normalized vegetation index (NDVI), and the average adult meerkat body condition at the Kalahari Meerkat Project, from 2002 to 2022. FIGURE S7. The relationship between the age at first weighing (emergence) and body weight in wild meerkats. FIGURE S8. The effect of dominance status, maternal age, and group size on variation in meerkat body weight at the start of pregnancy. FIGURE S9. Effects of various predictors on the duration and rate of gestational weight gain in wild meerkats. FIGURE S10. The duration of gestational weight gain was not associated with any fitness measure in wild meerkats. FIGURE S11. The quadratic effect of temperature on gestation lengths in wild meerkats. Increases in temperature are associated with shorter gestation lengths, up until around 30ºC, after which point the average gestation length levels off. TABLE S1. Within-pregnancy correlations in the shape parameters of the gestational weight gain curve for wild meerkats. TABLE S2. Models of gestational weight dynamics fitted in the study. TABLE S3. Model 1 output. TABLE S4. Model 2 output. TABLE S5. Model 3 output: maternal, social, and environmental effects on variation in gestational body weight in wild pregnant meerkats. TABLE S6. Model 4 output: The effect of supplemental feeding throughout pregnancy on gestational body weight in wild meerkats. TABLE S7. Model output: factors affecting gestation length in wild meerkats. TABLE S8. Model 5 output: body weight changes for meerkat pregnancies that started with an observed oestrus or mating event. TABLE S9. The effect of gestational weight gain parameters on the body weight of meerkat pups at emergence from the birth burrow (approximately 18 days). TABLE S10. The effect of gestational weight gain parameters on meerkat pup telomere length at emergence. TABLE S11. The effect of gestational weight gain parameters on meerkat pup survival to independence (90 days). TABLE S12. Model output: the effect of gestational weight gain parameters on meerkat pup survival to adulthood (1 year).1. In wild mammals, early postnatal growth strongly affects offspring survival and fitness, but little is known about the causes and consequences of variation in prenatal growth. 2. We investigated whether gestational weight gains vary according to maternal traits and social and environmental conditions, and how prenatal growth affects the fates of the resulting offspring, using an exceptionally large sample of repeated pregnant body weight records from individually recognizable wild meerkats (Suricata suricatta). 3. Pregnant meerkats' body weights remained stable during the first half of gestation and then increased linearly until they gave birth. 4. Gestational weight gains were more rapid under favourable environmental conditions and when mothers were experimentally food-supplemented, suggesting that nutrition strongly determines prenatal growth. 5. While social conditions and reproductive competition shape postnatal growth in many social vertebrates (including meerkats), these factors had a limited effect on prenatal growth, and adjustment to gestation lengths were modest and unrelated to social factors. 6. Pups that grew faster in utero were heavier when they emerged from the birth burrow yet this rapid growth was not associated with shortened leukocyte telomeres, and they were consequently more likely to survive to adulthood. 7. Broadly, we identified pronounced variation in gestational weight gains, which is largely driven by food availability and strongly predicts offspring birth weights and survival. 8. Our findings also highlight constraints in the flexibility of prenatal growth and gestation lengths in this species, which may limit adjustments in response to prevailing social conditions, and enhance selection for flexibility in postnatal growth.en© 2025 The Author(s). Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society. This is an open access article under the terms of the Creative Commons Attribution License.GestationGestational weight gainMaternal investmentMeerkat (Suricata suricatta)PregnancyPrenatal growthTelomeresArticle