OBJECTIVES: Great apes show considerable diversity in socioecology and life history, but knowledge of their physical growth in natural settings is scarce. We characterized linear body size growth in wild mountain gorillas from Volcanoes National Park, Rwanda, a population distinguished by its extreme folivory and accelerated life histories. METHODS: In 131 individuals (0.09-35.26 years), we used non-invasive parallel laser photogrammetry to measure body length, back width, arm length and two head dimensions. Nonparametric LOESS regression was used to characterize cross-sectional distance and velocity growth curves for males and females, and consider links with key life history milestones. RESULTS: Sex differences became evident between 8.5 and 10.0 years of age. Thereafter, female growth velocities declined, while males showed increased growth velocities until 10.0-14.5 years across dimensions. Body dimensions varied in growth; females and males reached 98% of maximum body length at 11.7 and 13.1 years, respectively. Females attained 95.3% of maximum body length by mean age at first birth. Neonates were 31% of maternal size, and doubled in size by mean weaning age. Males reached maximum body and arm length and back width before emigration, but experienced continued growth in head dimensions. CONCLUSIONS: While comparable data are scarce, our findings provide preliminary support for the prediction that mountain gorillas reach maximum body size at earlier ages compared to more frugivorous western gorillas. Data from other wild populations are needed to better understand comparative great ape development, and investigate links between trajectories of physical, behavioral, and reproductive maturation.
OBJECTIVES: Great apes show considerable diversity in socioecology and life history, but knowledge of their physical growth in natural settings is scarce. We characterized linear body size growth in wild mountain gorillas from Volcanoes National Park, Rwanda, a population distinguished by its extreme folivory and accelerated life histories. METHODS: In 131 individuals (0.09-35.26 years), we used non-invasive parallel laser photogrammetry to measure body length, back width, arm length and two head dimensions. Nonparametric LOESS regression was used to characterize cross-sectional distance and velocity growth curves for males and females, and consider links with key life history milestones. RESULTS: Sex differences became evident between 8.5 and 10.0 years of age. Thereafter, female growth velocities declined, while males showed increased growth velocities until 10.0-14.5 years across dimensions. Body dimensions varied in growth; females and males reached 98% of maximum body length at 11.7 and 13.1 years, respectively. Females attained 95.3% of maximum body length by mean age at first birth. Neonates were 31% of maternal size, and doubled in size by mean weaning age. Males reached maximum body and arm length and back width before emigration, but experienced continued growth in head dimensions. CONCLUSIONS: While comparable data are scarce, our findings provide preliminary support for the prediction that mountain gorillas reach maximum body size at earlier ages compared to more frugivorous western gorillas. Data from other wild populations are needed to better understand comparative great ape development, and investigate links between trajectories of physical, behavioral, and reproductive maturation.
Authors: Edward Wright; Jordi Galbany; Shannon C McFarlin; Eric Ndayishimiye; Tara S Stoinski; Martha M Robbins Journal: PLoS One Date: 2020-06-03 Impact factor: 3.240
Authors: Christopher B Ruff; Juho-Antti Junno; Winnie Eckardt; Kirsten Gilardi; Antoine Mudakikwa; Shannon C McFarlin Journal: Philos Trans R Soc Lond B Biol Sci Date: 2020-09-21 Impact factor: 6.237
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Authors: Edward Wright; Sven Grawunder; Eric Ndayishimiye; Jordi Galbany; Shannon C McFarlin; Tara S Stoinski; Martha M Robbins Journal: Sci Rep Date: 2021-04-08 Impact factor: 4.379
Authors: Kate McGrath; Amandine B Eriksen; Daniel García-Martínez; Jordi Galbany; Aida Gómez-Robles; Jason S Massey; Lawrence M Fatica; Halszka Glowacka; Keely Arbenz-Smith; Richard Muvunyi; Tara S Stoinski; Michael R Cranfield; Kirsten Gilardi; Chantal Shalukoma; Emmanuel de Merode; Emmanuel Gilissen; Matthew W Tocheri; Shannon C McFarlin; Yann Heuzé Journal: Proc Biol Sci Date: 2022-02-23 Impact factor: 5.530