10.5061/DRYAD.14MB6
Clemente, Christofer J.
University of Queensland
Data from: The evolution of bipedal running in lizards suggests a
consequential origin may be exploited in later lineages.
Dryad
dataset
2014
Adaptive Radiations
Selection - Natural
Exaptation
rates of evolution
co-opted traits
2014-04-23T18:26:10Z
2014-04-23T18:26:10Z
en
https://doi.org/10.1111/evo.12447
25217 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
The origin of bipedal locomotion in lizards is unclear. Modeling studies
have suggested that bipedalism may be an exaptation, a byproduct of
features originally designed to increase maneuverability, which were only
later exploited. Measurement of the body center of mass (BCOM) in 124
species of lizards confirms a significant rearward shift among bipedal
lineages. Further racetrack trials showed a significant acceleration
threshold between bipedal and quadrupedal runs. These suggest good general
support for a passive bipedal model, in which the combination of these
features lead to passive lifting of the front of the body. However,
variation in morphology could only account for 56% of the variation in
acceleration thresholds, suggesting that dynamics have a significant
influence on bipedalism. Deviation from the passive bipedal model was
compared with node age, supporting an increase in the influence of
dynamics over time. Together, these results show that bipedalism may have
first arisen as a consequence of acceleration and a rearward shift in the
BCOM, but subsequent linages have exploited this consequence to become
bipedal more often, suggesting that bipedalism in lizards may convey some
advantage. Exploitation of bipedalism was also associated with increased
rates of phenotypic diversity, suggesting exploiting bipedalism may
promote adaptive radiation.
Clemente_Supp_data1Clemente_Supp_data1.csv contains data for the
horizontal body center of mass and snout vent length for 124 species of
lizards. Species names are as formatted in the Pyron et al. (2013)
phylogeny. BCOM.hip represents the mean horizontal position of the body
center of mass forward from the hip. SVL is the mean snout to vent length
for each species measured. Two additional columns classify bipedal
locomotion. Column 4 (bipedal) was used in the study and is divided into
species for which bipedal locomotion has been observed (yes), with all
other species being placed in the unknown category (unknown). Column 5
(bi.cat) is similar with the exception that species are divided into
bipedal, where bipedalism is observed (yes), where only quadrupedal
locomotion was observed after high speed filming and observation (no), and
unknown where it is ambiguous
(unknown).Clemente_Supp_data2Clemente_Supp_data2.csv contains
accelerations for bipedal, quadrupedal and transitional strides for each
species. Column 1 contain species names, formatted as in the Pyron et al.
(2013) phylogeny. Column 2 contains mean acceleration during the stride.
Column 3 contains the gait category for each stride as quadrupedal (0),
transitional (0.5) or bipedal
(1.0).Clemente_Supp_data3Clemente_Supp_data3.csv contains the stride
kinematics used to determine predicted threshold kinematics for each
species. Column 1 contain species names, formatted as in the Pyron et al.
(2013) phylogeny. Column 2 contain the average position of the foot
relative to the hip during the stance phase (xfh). Column 3 contains the
average hip height during the stance phase used to approximate the
vertical COM (ybc). Column 4 contains hind limb length (HLL) used to
standardize kinematics for size. Column 5 contains the horizontal BCOM
forward of the hip (BCOM). Pyron, R. A., F. T. Burbrink, and J. J. Wiens.
2013. A phylogeny and revised classification of Squamata, including 4161
species of lizards and snakes. BMC evolutionary biology 13:93.