Fitness

1
Fitness?
- Hard to measure evolutionary consequences of
individual variation in performance abilities
- Use estimates of fitness mating success
locomotor performance growth rate survival
etc.
- Role of genes AND environment
- Break research into 1. Gene to performance
2. Performance outward
2
Morphology
Physiology Biochemistry Genes?
Performance
Sprint Speed Endurance etc.
Fitness
Survival and Reproduction
3
Constraints and Trade-offs ?
- Temperature - Water - Energy
These, and their interactions, affect -
activity period - growth rate -
locomotor performance - reproductive effort
- etc.
4
Constraints and Trade-offs ?
Pough et al., 2001 Chap. 6
e.g., - lizards are faster when warmer (up to
a point)
- dehydrated anurans are more prone to fatigue
and dont jump as well
- dehydrated anurans have lower optimal
temperatures
5
Constraints and Trade-offs ?
e.g., Ctenophorus ornatus (an Australian lizard)
growth rate () mating success
growth rate (-) surviving dry summer
growth rate (-) ability to regulate salt and
water
growth rate () survive cold winters
Ctenophorus nuchalis
Alternative strategies!
6
Speed and Endurance are positively correlated
Residuals (from regressions on body mass)
Speed and Endurance do not trade-off
r2 0.187 p 0.039
23 Species (Adult Males)
7
Speed-Endurance Trade-Offs
Body Mass
Wilson et al. 2002
Xenopus laevis
1. Peroneus Muscle 2. Whole Animal
8
Speed-Endurance Trade-Offs
Wilson et al. 2002
Peroneus Muscle
Xenopus laevis
Trade-off between speed and endurance at level
of individual muscle, but not at level of
animals
Workloop
- Fiber Recruitment - Intermittent -
Extrapolate from 1 muscle - Athletes, Health,
Injury
9
The Speed - Endurance trade-off question is
unresolved
Taxa Humans 18 mammal spp. Garter snakes 1
Sceloporus 1 Lacertid 4 Lacertids 12 Lacertids
Trade-off? depends NO NO NO NO YES YES
Inter/Intra Intra Interspecific Intra Intra
Intra Interspecific Interspecific
Reference Heinrich 1985 Garland et al. 1988
Brodie and Garland 1993 Tsuji et al. 1989
Sorci et al. 1995 Huey et al. 1984
Vanhooydonck et al. 2001
10
Metabolism
Feeding in Herps - more time, energy to
consume large prey but, cost lt1 energy from
meal - time minimizers (many small) -
movement minimizers (few large) sit and wait
active foraging
Pough et al., 2001 Fig 6-17
11
Herps Aspects of LOCOMOTION
First tetrapods ashore in Devonian (360 ma) -
modified fleshy finned fishes - fish-like
lateral undulations - ancestral pattern -
becomes modified...
Diversity - modes - limb and body shape
Small body size and elongate shape possible in
ectotherms. Why?
12
Locomotion
Modes Terrestrial how - quadrupedal
- bipedal - limbless
where - surface - fossorial -
climbing
Aquatic - body undulations - limbs
Aerial - modifications
13
Locomotion
Physical Principles
Newton 1st Law - at rest, stay at rest -
in motion, stay in motion 2nd Law - F ma
(Force mass x acceleration) 3rd Law - for
every action there is an equal and
opposite reaction
Locomotion is result of environment pushing
against an organism as it applies a force.
14
Locomotion
Locomotion is Result of environment pushing
against an organism as it applies a Force.
Two vectors important 1. up against gravity
(Vertical) 2. thrust in direction of motion
(Propulsion)
R
Pough et al. 2001 Figure 8-1
F
15
Locomotion
Locomotion is Result of environment pushing
against an organism as it applies a Force.
Two vectors important 1. up against gravity
(Vertical) 2. thrust in direction of motion
(Propulsion)
R
Pough et al. 2001 Figure 8-1
F
16
Locomotion
Gait - timing and pattern of limb movements
- Walk each foot on ground for at least half
of gait cycle - Run each foot on
ground for less than half of gait cycle
Stride cycle of limb movements - propulsion
- recovery
17
Locomotion
joint
Lever Systems Lever Rigid bar that pivots
around a fulcrum
bone
Law of the Lever Fi x Li Fo x Lo in-force
times in-lever out-force times out- lever
Pough et al. 2001 Figure 8-3
18
Levers
Pough et al. 2001 Figure 8-3
Antagonistic muscles
19
Locomotion
Terrestrial w/ limbs - ancestral sarcopterygian
locomotion - sprawling in lepidosaurs and
salamanders - includes lateral undulations
- slightly more erect in crocodylians and in
chamaeleons (narrow profile) and in dinosaurs
(support great weight)
20
Locomotion
How does sprawling terrestrial locomotion work?
a. upper segment swung anteroposteriorly
b. girdle thrust forward as body axis bends
laterally
c. upper element (humerus/femur) rotated about
its long axis
Pough et al. 2001 Figure 8-4
21
Locomotion
How does sprawling terrestrial locomotion work?
Lepidosaur specializations - vertebrae -
pectoral girdle - hindlimb
Vertebrae - allow lateral bending -
facilitates longer stride length
22
Locomotion
Lepidosaur specializations - vertebrae -
pectoral girdle - hindlimb
Pectoral Girdle - tongue and groove joint at
coracoid and sternum - allows coracoid to
slide relative to sternum
Pough et al. 2001 Figure 8-5
23
Locomotion
Lepidosaur specializations - vertebrae -
pectoral girdle - hindlimb
Hindlimb - unusual tarsal bones first
4 metatarsals fused special shape of 5th
metatarsal (hook or L-shaped) 1st
class lever to extend ankle provide push
(like gastroc/ achilles tendon/ heel)

- ankle specializations also
24
Locomotion
Dynamic bipeds
- Support on two legs if in motion
Bipedal trends - long hindlimbs - short
forelimbs - short presacral vertebral moves
G backwards - relatively long tail
counterbalance - muscles of hindlimb moved
proximally longer tendons speed gt force -
elongate plantar tubercle of 5th metatarsal
increases in-lever of gastrocnemius -gt more
thrust
25
Locomotion
How increase speed?
Increase stride length - longer limbs (hind)
- run up on phalanges (not foot) - alter
kinematics of stride
Increase stride frequency - propulsion and
retraction - muscle twitch speed
26
Locomotion
How deal with sand?
Moveable substrate...
Fringes of scales on trailing edge of each toe
Uma spp.
27
Convergent Evolution
Callisaurus draconoides crinitus
(Stebbins, 1985)
Callisaurus draconoides draconoides
Zebra-tailed Lizard
- Fringes on Toes - Live in Sand
28
Herps Aspects of LOCOMOTION
Terrestrial Turtles - no axial bending of
vertebral column - slow - limbs in prolonged
contact - let body fall forward
Pough et al., 2001
29
Jumping! Locomotion
Anurans (...light and rigid) - use long
hindlimbs together - specialized pelvic girdle
Takeoff angle - max height if take off at 90
degrees - max distance if take off at 45 degrees
Takeoff velocity - weight lowers velocity and
height - longer legs facilitate acceleration
- hindlimb length correlated with jump ability
- remain aerodynamic in the air - land on
arciferal (ancestral) or firmisternal pectoral
girdle
30
Anuran Locomotion
Jumpers (Rana) - shorter ilia, round sacral
diapophyses ilium rotates to straighten trunk
- take off at 45 degrees
Hoppers/walkers - wider iliosacral joint,
ilium swings laterally - allows lateral gait
Other (some fossorial toads and some branch
walkers and Pipidae) - ilium slides
anteroposteriorly - lengthens stride
Pough et al., 2001
31
Limbless Terrestrial Locomotion
- Caecilians, Amphisbaenians, Snakes, Many
Lizards - limblessness with elongation
- multiple origins amphisbaenians lost
hindlimbs first (e.g., Bipes) squamate groups
lost forelimbs first (e.g., some vestigial
snake hindlimbs)
32
Snake Terrestrial Locomotion
6 modes No static points 1. Lateral
undulation 2. Slide-pushing
Static points 1. Rectilinear 2. Concertina 3.
Sidewinding 4. Saltation
Several hundred vertebrae Complex,
multi-segmented muscle chains
spinalis-semispinalism, longissimus dorsi,
iliocostalis
33
Snake Terrestrial Locomotion
Lateral Undulation - most widely used -
horizontal waves down alternating sides of body
- generate force at fixed points in environment
- body pushes posterolaterally - lateral
components cancel
Pough et al., 2001
vs. limbed locomotion 1. No fixed points on body
for propulsion body moved past fixed points in
environment 2. No recovery phase (limb
retraction) 3. No real vertical component, but
combat friction
34
Snake Terrestrial Locomotion
Slide Pushing - resembles lateral undulation -
but no fixed points in the environment - rapid
body waves to generate some friction on smooth
surfaces
Pough et al., 2001
35
Snake Terrestrial Locomotion
Rectilinear - muscles on both sides of body
simultaneously - move in straight line - heavy
bodied snakes (boids and vipers)
- 2 sets of costocutaneous muscles from ribs to
ventral skin
A. Costocutaneous superior muscles pull skin
forward relative to ribs B. Ventral scales
anchored to substrate C. Costocutaneous inferior
pulls ribs (and vertebrae and everything else)
forward relative to stationary ventral skin
36
rectilinear locomotion
Fig. 8-15 Pough et al. 2001
37
Snake Terrestrial Locomotion
Concertina - slow - high energy - repeated
establishment of fixed and stable contact with
substrate
- used in tunnels - used by arboreal snakes
Pough et al., 2001
38
Snake Terrestrial Locomotion
Sidewinding - low friction or shifting
substrates - most snakes capable - forces
directed vertically
- sections of body alternately lifted up,
moved forward, set down
- snake usually in contact at two points
- can be more efficient than lateral
undulation
Pough et al., 2001
39
Snake Terrestrial Locomotion
Saltation ! - small Bitis caudalis (Viperidae)
- rapid straightening from anterior to posterior

http//www.plumed-serpent.com/dscour.html
40
Aquatic Locomotion
Water is dense and viscous
- support against gravity - resistance for
propulsion (e.g., webbed feet) - difficult to
move through - requires power
drag resistance of water due to viscosity -
boundary layer - laminar flow vs. turbulence
- improved boundary layer retention
decreases turbulence and drag
hydrofoil (pressure differential for lift)
Pough et al., 2001
41
Aquatic Locomotion
1. Lateral undulations - each part of body
generates force as well as friction -
undulations LARGER as move posteriorly
(opposite on land) increases in surface area
sea snakes, crocodiles, marine iguanas
2. Oscillatory (paired appendages) drag or lift
based - Frogs and turtles (no lateral flexion)
simultaneous, webbed Xenopus with special
sacral articulation - Marine turtles fly
through water generate lift on up and down
stroke of forelimbs hindlimbs for steering
42
Fossorial Locomotion
- Fossorial anurans generally use hindlimbs to
dig - shorter for increased power
- Common in legless groups - Scolecophidia -
Uropeltidae (Alethinophidia) - Amphisbaenians
and other Lizards - Caecilians
- specialized skulls robust, shaped to match
behavior - smooth skin - reduced number of
scales (if present)
43
Fossorial Locomotion
- undulatory, concertina, rectilinear
- internal concertina
Pough et al., 2001
44
Fossorial Locomotion
- sand diving 6 lizard families fringes on
toes counter sunk lower jaw labial scales
form cutting edge
- sand swimming e.g., Scincus ears sensitive
to seismic activity e.g., Chionactis
(shovel-nosed)
Uma spp.
- breathing?
45
Climbing Locomotion (Scansorial)
1. grasping or 2. adhesion
1. Grasping - more common in reptiles -
prehensile tails e.g. Bolotiglossa
Scincidae, Chamaeleonidae Imantodes
gap-bridging
- prehensile feet Chamaeleonidae
zygodactylus minimal lateral undulation
highly mobile pectoral girdle
Chamaeleo jacksonii
46
Climbing Locomotion (Scansorial)
2. Adhesion - salamanders, frogs, lizards
bolotigolossines with webbed feet - capillary
action if small - suction if larger (lift
center)
Pough et al., 2001
A. toepads - some anurans and a salamander
genus - polygonal tiles with deep crevices
between - use capillary adhesion, lots of
surface area - larger species with similar
tissue at toe joints - detach by peeling toe
forward - Hylidae, Centrolenidae w/ intercalary
cartilage
47
Climbing Locomotion (Scansorial)
2. Adhesion (cont) - instead of capillary
action, some lizards use weak forces (shared
electrons) - B. dry adhesion
structure of scansors (not toepads) -
platelike subdigital lamellae, - transversely
expanded scales, - covered with setae each
with spatulate ending (surface area)
- complex tendon and vascular control to get
maximal close contact
some larger geckos add scansors beneath tail
48
Climbing Locomotion (Scansorial)
2. Adhesion (B. cont)
scansors - platelike subdigital lamellae -
transversely expanded scales - complex tendon
and vascular control
Van der Waals forces
setae each with spatulate ending
Pough et al., 2001
49
Aerial Locomotion
- Fall - Parachute - Glide
Pough et al., 2001
- body mass to surface area - webbing, skin
flaps (with ( patagia) or without ribs)
50
1. Aquatic Locomotion -relatively efficient b/c
neutral buoyancy 2. Aerial Locomotion (birds
more than herps) -need to generate lift to
fight gravity -airfoil 3. Terrestrial rather
expensive -Center of Mass up and down (muscles
x2)
51
(No Transcript)