TY - JOUR
T1 - Eye size at birth in prosimian primates
T2 - Life history correlates and growth patterns
AU - Cummings, Joshua R.
AU - Muchlinski, Magdalena N.
AU - Kirk, E. Christopher
AU - Rehorek, Susan J.
AU - DeLeon, Valerie B.
AU - Smith, Timothy D.
N1 - Funding Information:
This study was supported by grants from the Pennsylvania State System of Higher Education and Slippery Rock University. For training in phylogenetic comparative methods, we thank the AnthroTree Workshop. We thank C. Vinyard for scanning the several fetal and infant cadavers. We are grateful to J. Wible for allowing us to use photographic equipment to produce . Thanks to Sarah Zehr and DLC veterinary staff for preserving valuable cadaveric specimens. This is DLC publication number 1218.
PY - 2012/5/2
Y1 - 2012/5/2
N2 - Background: Primates have large eyes relative to head size, which profoundly influence the ontogenetic emergence of facial form. However, growth of the primate eye is only understood in a narrow taxonomic perspective, with information biased toward anthropoids. Methodology/Principal Findings: We measured eye and bony orbit size in perinatal prosimian primates (17 strepsirrhine taxa and Tarsius syrichta) to infer the extent of prenatal as compared to postnatal eye growth. In addition, multiple linear regression was used to detect relationships of relative eye and orbit diameter to life history variables. ANOVA was used to determine if eye size differed according to activity pattern. In most of the species, eye diameter at birth measures more than half of that for adults. Two exceptions include Nycticebus and Tarsius, in which more than half of eye diameter growth occurs postnatally. Ratios of neonate/adult eye and orbit diameters indicate prenatal growth of the eye is actually more rapid than that of the orbit. For example, mean neonatal transverse eye diameter is 57.5% of the adult value (excluding Nycticebus and Tarsius), compared to 50.8% for orbital diameter. If Nycticebus is excluded, relative gestation age has a significant positive correlation with relative eye diameter in strepsirrhines, explaining 59% of the variance in relative transverse eye diameter. No significant differences were found among species with different activity patterns. Conclusions/Significance: The primate developmental strategy of relatively long gestations is probably tied to an extended period of neural development, and this principle appears to apply to eye growth as well. Our findings indicate that growth rates of the eye and bony orbit are disassociated, with eyes growing faster prenatally, and the growth rate of the bony orbit exceeding that of the eyes after birth. Some well-documented patterns of orbital morphology in adult primates, such as the enlarged orbits of nocturnal species, mainly emerge during postnatal development.
AB - Background: Primates have large eyes relative to head size, which profoundly influence the ontogenetic emergence of facial form. However, growth of the primate eye is only understood in a narrow taxonomic perspective, with information biased toward anthropoids. Methodology/Principal Findings: We measured eye and bony orbit size in perinatal prosimian primates (17 strepsirrhine taxa and Tarsius syrichta) to infer the extent of prenatal as compared to postnatal eye growth. In addition, multiple linear regression was used to detect relationships of relative eye and orbit diameter to life history variables. ANOVA was used to determine if eye size differed according to activity pattern. In most of the species, eye diameter at birth measures more than half of that for adults. Two exceptions include Nycticebus and Tarsius, in which more than half of eye diameter growth occurs postnatally. Ratios of neonate/adult eye and orbit diameters indicate prenatal growth of the eye is actually more rapid than that of the orbit. For example, mean neonatal transverse eye diameter is 57.5% of the adult value (excluding Nycticebus and Tarsius), compared to 50.8% for orbital diameter. If Nycticebus is excluded, relative gestation age has a significant positive correlation with relative eye diameter in strepsirrhines, explaining 59% of the variance in relative transverse eye diameter. No significant differences were found among species with different activity patterns. Conclusions/Significance: The primate developmental strategy of relatively long gestations is probably tied to an extended period of neural development, and this principle appears to apply to eye growth as well. Our findings indicate that growth rates of the eye and bony orbit are disassociated, with eyes growing faster prenatally, and the growth rate of the bony orbit exceeding that of the eyes after birth. Some well-documented patterns of orbital morphology in adult primates, such as the enlarged orbits of nocturnal species, mainly emerge during postnatal development.
UR - http://www.scopus.com/inward/record.url?scp=84860469228&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0036097
DO - 10.1371/journal.pone.0036097
M3 - Article
C2 - 22567127
AN - SCOPUS:84860469228
SN - 1932-6203
VL - 7
JO - PLoS ONE
JF - PLoS ONE
IS - 5
M1 - e36097
ER -