E138 Locomotion

ex of facultative parthenogens

some varanid lizards

what does lab data of whiptail lizards indicate about parthenogens

parthenogenic offspring were all female and homozygous

• no alleles from the other species

• each box = locus on a chromosome

• each color = chromosome

what does lab data of wild-caught sawfish indicate about parthenogens

some individuals were likely the result of parthenogenesis

• high homozygosity

consequences of homozygosity on conservation

high homozygosity = low genetic diversity and high mortality

results in weird phenotypes

• breeding plans assume sexual reproduction

ex of obligate parthenogens

whiptail lizards

whiptail lizard reproduction

female lizard acting as a female

• high estradiol

female lizard acting as a male (stimulates ovary growth)

• hits ovulation → crash in estradiol → rise of progesterone = acting as a male

• cyclic

hormones drive this reproduction

how do obligate parthenogens avoid the homozygosity problem

they are triploids

• they are great model for studying what influences sexaul behaviors (genetics, hormones, neural, environment, toxins) and how they evolved

cost of transport

energy consumed to transport one unit of body mass over one unit of distance at a particular speed

cot equation

COT = (L O2/kg/hr) / (km/hr)

what impacts COT

energy efficiency, environment, morphology, behavior

• results in energy allocation trade-off and consequences

individual differences in cot

fitness, selection gradient, growth

group function in cot

cohesion, assortment, gene flow, population

species differences in cot

community, food web, conservation

cot varies by … and …

mode and size

most inefficient way to move

running (for most)

cheapest mode of transport

swimming

flying and cot

intermediate between swim (least) and run (most)

size and cot

smaller size = more expensive to move around

reason why swimming has such a low cot for some species

buoyancy

• swim bladder

• lipids

moving through water or air

reduced air pressure based on the shape of fins or wings

• diverse feathers = big feathers for soearing

fish head movement and swim speed

inverse relationship

• fastest when the head stays stable, but moves their body

why do we care about cot and movements

bio-inspired robotics

cot of robots

the tutle robot has greater COT for crawling, walking, and swimming in comp to an actual turtle

how does cot change when swimming a school

school of fish have a lower cot than swimming by themselves

• drafting

supracoracoideus contraction

produces the wing upstroke in flying

pectoralis contraction

producs the downstoke in flying

flying cot

parabolic relationship between speed and mechanical power

• lowest energy use = bottom of the parabola

• best for distance = greater speed with relatively low energy use

how to identify the best flight speed

draw a line from 0 through the bottom of the parabola

does all flight cost the same amount of energy

no

• hummingbirds hover = most expensive

thermal soaring

ride on top of the thermals (warm air rising)

terrestrial locomotion

least efficient

• COT varies with speed and gait

VO2 and speed relationship

VO2 increases linearly with speed

gallop

legs off the ground

speed and gait

lowest cot is similar between walk and trot in horses

hopping

in a 5kg quadruped, the O2 consumption increases linearly with speed

in a 5 kg wallaby, the O2 consumption increases then plateaus with speed

moving without legs

sidewinding

• move faster = consuming more O2

• only 2 parts of the body are on the ground