Fitness? - Hard to measure evolutionary consequences of individual variation in performance abilities - Use estimates of fitness mating success locomotor

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

Performance

Physiology Biochemistry Genes?

Fitness

Morphology

Sprint Speed Endurance etc.

Survival and Reproduction

Constraints and Trade-offs ?

These, and their interactions, affect: - activity period - growth rate - locomotor performance - reproductive effort - etc.

- Temperature - Water - Energy

e.g., - lizards are faster when warmer (up to a point)

- dehydrated anurans have lower optimal temperatures

Constraints and Trade-offs ? Pough et al., 2001

Chap. 6

- dehydrated anurans are more prone to fatigue and don’t jump as well

Constraints and Trade-offs ? e.g., Ctenophorus ornatus (an Australian lizard)

growth rate (+) mating success

growth rate (-) surviving dry summergrowth rate (-) ability to regulate salt and

water growth rate (+) survive cold winters

Alternative strategies!

Ctenophorus nuchalis

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-1 -0.5 0 0.5 1

log Endurance (s)

log

Sp

rin

t S

pee

d (

m/s

)

Sceloporus

Sand

Horned

Crotaphytidae

Agamidae

Teiidae

Lacertidae

Scincidae

Anguidae

Speed and Endurance are positively correlated

23 Species (Adult Males)

Residuals (from regressions

on body mass) Speed and Endurance

do not trade-off

r2 = 0.187 p = 0.039

Speed-Endurance Trade-Offs

Wilson et al. 2002

Xenopus laevis1. Peroneus Muscle 2. Whole Animal

Body Mass

Speed-Endurance Trade-Offs

Wilson et al. 2002

Xenopus laevis

Workloop

Trade-off between speed and endurance at level of individual muscle, but not at level of animals

Peroneus Muscle

- Fiber Recruitment - Intermittent - Extrapolate from 1 muscle - ’Athletes’, Health, Injury

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

Metabolism

Feeding in Herps - more time, energy to consume large prey but, cost <1% energy from meal - time minimizers (many small) - movement minimizers (few large) ~ sit and wait ~ active foraging

Pough et al., 2001 Fig 6-17

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?

Locomotion Modes: Terrestrial how - quadrupedal

- bipedal - limbless

Aquatic - body undulations - limbs

Aerial - modifications

where - surface - fossorial - climbing

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.

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

F Pough et al. 2001

Figure 8-1

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

F Pough et al. 2001

Figure 8-1

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

Lever Systems Lever = Rigid bar that pivots around a fulcrum

bone

joint

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

Levers


Antagonistic muscles

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)

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


Locomotion

How does sprawling terrestrial locomotion work?Lepidosaur specializations

- vertebrae - pectoral girdle - hindlimb

Vertebrae - allow lateral bending - facilitates longer stride length

Locomotion

Lepidosaur specializations

- vertebrae - pectoral girdle - hindlimb

Pectoral Girdle - tongue and groove joint at coracoid and sternum - allows coracoid to slide relative to sternum


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

Locomotion

Dynamic bipeds - Support on two legs if in

motionBipedal trends - long hindlimbs - short forelimbs - short presacral vertebral

moves G backwards - relatively long tail

counterbalance - muscles of hindlimb moved proximally

longer tendons speed > force

- elongate plantar tubercle of 5th metatarsal increases in-lever of gastrocnemius -> more

thrust

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

Locomotion

How deal with sand?

Moveable substrate...

Fringes of scales on trailing edge of each

toe

Uma spp.

Convergent Evolution

Callisaurus draconoides draconoides (Stebbins, 1985)

Callisaurus draconoides crinitus

- Fringes on Toes - Live in Sand

Zebra-tailed Lizard

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

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

Anuran Locomotion

Jumpers (Rana) - shorter ilia, round sacral diapophyses

ilium rotates to straighten trunk - take off at 45 degrees

Pough et al., 2001

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”

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)

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


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

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

Pough et al., 2001


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


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

Fig. 8-15 Pough et al. 2001

rectilinear locomotion


Concertina - slow - high energy - repeated establishment of fixed and

stable contact with substrate

Pough et al., 2001

- used in tunnels - used by arboreal snakes


Sidewinding - low friction or shifting substrates - most snakes capable - forces directed ~vertically

Pough et al., 2001

- sections of body alternately lifted up, moved forward, set down

- snake usually in contact at two points

- can be more efficient than lateral undulation


Saltation ! - small Bitis caudalis (Viperidae) - rapid straightening from anterior to posterior

http://www.plumed-serpent.com/dscour.html

Aquatic Locomotion

Water is dense and viscous

Pough et al., 2001

- 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)

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

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)


- undulatory, concertina, rectilinear

- internal concertina

Pough et al., 2001


- 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)

- breathing?

Uma spp.

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


2. Adhesion - salamanders, frogs, lizards

bolotigolossines with webbed feet - capillary action if small - suction if larger (lift center)

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

Pough et al., 2001


2. Adhesion (con’t) - instead of capillary action, some lizards use weak forces (shared

electrons) - B. dry adhesion

some larger geckos add scansors beneath tail

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


2. Adhesion (B. con’t) scansors: - platelike subdigital lamellae

- transversely expanded scales - complex tendon and vascular

control

Pough et al., 2001

setae:each

with spatulate ending

Van d

er

Waals

forc

es

Aerial Locomotion

- Fall - Parachute

- Glide

- body mass to surface area - webbing, skin flaps (with (= patagia) or without ribs)

Pough et al., 2001

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)

Movements and Orientation

Acquisition of Resources - food and water - mates - basking or hibernation sites - nesting sites - etc.

Why move?

Costs and Benefits - Energy - Predation - Exposure


Herps: - most are small - a few travel long distances

Why move?

Consider: - home ranges - territories - migration - dispersal - homing


Movement and Biology:

Individuals - water and temperature - foraging strategy - energy balance - mating system - predation pressure - interspecific encounters

e.g., dispersal often high juvenile

mortality toads sea turtles ~clutch size

Populations - metapopulations - genetic structure - philopatry - conservation corridors


Mark and Recapture...

Methods

Continuous Monitoring...


1. Station keeping (home range) - foraging - commuting - defense

Types of Movement

2. Ranging ~Dispersal - mate searching

3. Dispersal - increase space between

indivs4. Migration


(Convex polygon, Other methods)

Home Range Movements

Effect of body size and ecology

- Fidelity - Shifting - Nomadic

Pough et al. 2001


1. Depleted or 2. Not depleted

Resources

Small home ranges if abundant resources or quickly regenerated

Large home ranges (or nomadic) if patchy resources or slowly regenerated

Predict from abundance, patchiness, renewal rate of food

-Green and Marine Iguanas

- Dermochelys - Vertebrate Diet

10-4, Pough et al. 2001

Varanus komodoensis


Territoriality (= Home Range Defense)Predict from abundance, patchiness, renewal rate

of foodCosts of Defense vs. Increased availability of resources

Favored if - resources moderately abundant - even or moderately patchiness - high renewal rate

Not Favored if - very high or very low resource abundance - high patchiness - low renewal rate


Territoriality

- Patchy distribution favors overlap of home ranges- Only use a small portion of HR at one time

- Too costly to defend (e.g., small verts or hidden insects)

HR defense - rare in actively foraging lizards - common in sit-n-wait insectivores

Pough et al. 2001


Territoriality

Sexual differences (~ lizards)

Female - not territorial - home ranges overlap - may defend nest sites (smaller than HR)

Male - often territorial - includes HRs of several females - related to mating more than food

Satellite Males


Territoriality

Sexual differences (~ lizards)

Female - not territorial - home ranges overlap - may defend nest sites (smaller than HR)

Male - often territorial - includes HRs of several females - related to mating more than food

Satellite Males

Spools PIT tags Genetics Radios Fluorescent Powder etc.


Territoriality

Density:

Pough et al. 2001

6 12 6


Territoriality

Site Defense

Non-depletable resources - burrows - basking sites

Some actively foraging lizards without HR defensePlethodontid salamanders

moist retreats under logs, rocks


Migrations

about Resources

Annual/cyclical basis - breeding areas - nesting sites - hibernation dens - feeding areas

Changing habitat - droughts/floods - e.g. drying ponds


Migrations for Amphibian Mating

- To aquatic breeding sites - Weather dependent

Rana in Europe up to 15 km most only a few hundred meters

- Breeding site fidelity common e.g., newts in California for 11 years


Migrations for Reptile Mating

- not that common - females moving to suitable nesting sites - sometimes aggressive defense

Most squamates nest in HR

Green iguanas in Panama swim to small sandy island to nest


Migrations for Reptile Mating

Sea Turtles

Thousands of kilometers Feeding areas to nesting beaches

Chelonia mydas

Site Fidelity - Feed together - Nest at original beach - Males similar?

Dermochelys travels farthest

10-8, Pough et al. 2001


Overwintering Migrations

- e.g. Rana clamitans summer in pond winter in stream

- e.g. Crotalus viridis overwinter communally


Juvenile Movements

- Suitable Habitat

- Adult Competition

e.g. - amphibs from water to land - turtles from land to water

‘Rare’ long distance dispersal Heterozygosity

e.g. - unoccupied habitat (Bufo marinus)

- avoid cannibalism


Juvenile Reptile Movements

- Most squamate offspring in parents HRTo Disperse or NOT disperse

- Dispersal (and sociality) from nesting aggregations

-scarce resources -mating with relatives -cannibalism -long-lived species

-exposure to predation -energetically costly -move to marginal habitat -high adult mortality

- Iguana iguana in Panama - crocodilians - sea turtles


Ability to return to home range or breeding site

Homing Behavior

Species differ in homing ability

Amphibs - Plethodontids up to 60m - Taricha newt 2-8 kmAbility correlated with HR size?

Mmmm… doughnuts

Reptiles - turtles, crocodiles often move many km - lizards, snakes not well-studied

ability to return correlated w/ territoriality Motivatio

n


Orientation 1. Local 2. Compass 3. Magnetic/Navigation

1. Local - Visual and chemical cues

Plethodontids?:

10-13, Pough et al. 2001

- Audio cues e.g. breeding pond- use multiple cues

Sceloporus?

start



1. Local

Some local cues reliable even in new environment

- Downhill orientation (newts toward water)- Orientation toward bright blue and purple light

(hatchling sea turtles moving toward ocean)



2. Compass

- Y-axis orientation

- Sun ~ Moon, star

Ability to orient w/o local cues

10-16, Pough et al. 2001



2. Compass

- Y-axis orientation

- Sun ~ Moon, star

Ability to orient w/o local cues

10-16, Pough et al. 2001

Movements and OrientationOrientation 1. Local

2. Compass 3. Magnetic/Navigation

2. Compass - Sun pineal organ (‘third eye’) in all but crocs

Important for: - photoperiod entrainment - circadian rhythms - internal clock

In some lizards: more advanced parietal eye (with retina, lens, cornea)

10-18, Pough et al. 2001



2. Compass - Sun polarized light

- atmosphere scatters light - e-vector perpendicular to sun’s rays - related to position of sun - overcast interferes

Detect with extraoptic photoreceptors (usually pineal body)

10-20, Pough et al. 2001



3. Magnetic Orientation and Navigation

some herps can - detect earth’s magnetic field - relate to gravitational field (sea turtles) - magnetic receptors not well understood

True Navigation: 1. Compass Sense 2. Map Sense

- amphibs, alligators, box turtles, sea turtles - probably use with chemical and visual cues

Navigation via Magnetic Fields

- Pelagic Whales - Homing Pigeons - Cave salamanders - Bacteria etc.

- often a redundant system

- Magnetite particles (Fe3O4) orient with magnetic field

- Receptors detect -> processed in CNS

Documents

Fitness? - Hard to measure evolutionary consequences of individual variation in performance abilities - Use estimates of fitness mating success locomotor