Meeting Abstract

83.3  Friday, Jan. 7  Mouse phalangeal morphology and implications for agility within the fine-branch niche BYRON, CD*; OUY, L; ADENIYI, AR; VANVALKENBURGH, D; Mercer University; Mercer University; Mercer University; Mercer University cdbyron@gmail.com

Previous studies indicate significant phenotypic plasticity within the hindlimb and tail of a climbing mouse model. These mice engage in a kind of arboreal locomotion that is above branches and involves pedal and manual grasping. New data from both male and female climbers and controls include the proximal manual and pedal phalanges. Twenty male and female mice (ICR strain) were each divided into two experimental groups. Continuous Grasping Quadrupedal mice are reared on a narrow branch scaffolding whereby they are committed to an above-branch quadrupedal-like gait. Sedentary Control mice were reared in standard lab cages. Results show that climbing mice have significantly more gracile pedal phalanges caused by thinner diaphyses, however curvature is not influenced by fine-branch climbing. In the hand, proximal phalanges show no treatment effect from climbing. There is significant sexual dimorphism in these data. However, this does not statistically interact with effects from climbing. We hypothesize that the lack of manual phalangeal plasticity relates to an inability of mice to manually grasp the 3.3mm diameter substrate used in early experiments. To test this prediction experimental data are included here of mice crossing various substrate diameters (50 cm in length; 4.3-1mm in diameter). On thick substrates animals are measurably less agile. On thin branches secure manual and pedal grasping is employed and results in increased climbing performance. These results suggest that unique locomotor niche training (such as fine-branch arboreality) are not necessarily accompanied by skeletal plasticity.