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69 Cards in this Set

  • Front
  • Back

What defines a chordate?

Chordates are organisms that at some point in their development have the following characteristics:

- Notochord

- Pharyngeal slits

- Dorsal hollow nerve cord

- Postanal tail

- Endostyle

What kinds of groupings are denoted in the figure?

What kinds of groupings are denoted in the figure?

(a) monophyletic

(b) paraphyletic

(c) polyphyletic

What is convergent evolution? Provide some examples of convergent evolution.

Convergent evolution is where traits are shared between organisms that are not closely related and did not have a common ancestor that also expressed that trait.


- Plankton feeding cartilagenous fish (basking shark, whale shark,reef manta, megamouth shark)

- Hummingbird tongue and the tongue of other probers. Presence of papilla at the top of the tongue. Use of blood to extend papilla and increase SA.

- Flight in bats and birds. Bat wings are strengthened with an elastin network instead of rigid feathers. However, they can create similar vortices. Forms of flight also seen in sugar gliders, flying fish, gliding snakes

- Regional endothermy in fish. Also found in the flippers and flukes of some sea mammals (whale, turtle, seal). The countercurrent exchange mechanisms however, is widely used across most species.

- Saltatorial motion in kangaroo, ring-tailed lemur, rodents, lagomorphs. Good for rapid acceleration and sudden directional shifts.

- Winglessness in birds. If the birds have fewer predators, and rarely use flight in their foraging, it is more beneficial to lose this trait that is expensive to maintain. Species that live in low species richness areas actually have smaller flight muscles (low species richness being used as an indicator of number of predators)

- Biofluorescence in deep sea creatures.

- Infrared detection in snakes and bats. Use of pit organ (or pit organ like pit) to detect infrared energy. Snakes are able to integrate this ability with their vision and likely generate an image with the new information. Vampire bats have a similar organ, likely so they can more easily seek out hosts.

How do whale sharks sustain and power their large body size?

4 behavioral swimming tactics

- constant low speed, gliding, fixed low power, asymmetrical diving

Basking at surface to regain heat so they can perform deep dives in cold water.

Negative buoyancy (no swim bladder but use the liver and motion)

Specialized muscle plan where muscle core is surrounded by thin red muscle

Compare and contrast a shark's muscle plan with the muscle plan of a bony fish (i.e. tuna) focusing on how they function in thermogenesis.

Sharks: Inner core of white muscle surrounded by a thin layer of red muscle overlaid by connective tissue (thick layer). Used more to just retain heat so they can dive deep down. Speed is not much of a priority.

Tuna: Red muscle centered around vertebrae to keep spinal cord warm. Use to facilitate fast movements needed for hunting as well as reflexes.

What are some events that allowed for major diversification? Give examples of where this happened.

Evolution of jaws

- African ciclid fish have two sets of jaws that allowed them to exploit their environment. Pharyngeal jaw was very plastic and was capable of responding to environmental input. Allowed for plasticity within a generation. Works closely with neurocranium, is a trait that "evolves" quickly.

Evolution of wings

- Exploitation of new territory, be it to escape from predators to a higher elevation, or to be better predators themselves. There is also great disparity in birds in their degree of use and form of use for the wings.

What are some examples of evolutionary trade offs seen in animals today?

Shark teeth: sharp serrated teeth vs durability

Bird feathers: hydrophobicity vs iridescence; sexual selection vs survival (distribution of resources)

Avian eye: visual acuity vs range (binocular vision vs monocular)

Flight: Body weight vs lift; soaring ability vs balance on land

Toxicity in newts: TTX production vs production of offspring.

Resistance in snakes (TTX): TTX resistance vs crawling speed

What are the stages of vertebrate evolutionary radiation?

Habitat: Changed habitat causes changes in groups

Morphology: Certain morphologies allow exploitation of different niches.

Communication: Ability to communicate within species and with other taxa often heavily involved with survival and sexual selection

Describe major events in the evolution of tetrapods and their transition from water to land.

First major transition required would be the development of enough structure in the fins (pre-legs) to support body mass without buoyancy. Tiktaalik was the first fossil record of an intermediate limb between lobe finned fish and Acanthostega

Other difficulties of surviving on land include:

- Gas exchange

- Nitrogenous waste excretion

- Desiccation/dehydration

- Feeding

- Ion regulation

- Body support

What factors may have driven the transition of fish onto land?

Use of emersion as a strategy to escape poor water conditions, or predation.

To prevent overheating

Exploitation of a new, unoccupied niche

What cofactors that are driving the decrease in amphibian diversity?

Historical constraints: these are life-history constraints which make amphibians more susceptible to change.

Evolutionary compromises: trade offs. to adapt to changes, what can they compromise.

Non-adaptive evolution: having traits that may have been adaptive historically but are more non-adaptive now.

Evolution alters existing variation: loss of variation due to strong directional selection

Evolution takes time: species may not change fast enough to collectively adapt to the change.

Describe the controversy around the evolution of the shell in turtles.

Not sure which direction selection for the shell came from. I.e. were they formed from riblets or as extensions of the spinal cord?

Potentially it constricted the body cavity leading to decrease in metabolic, requiring them to have armour to defend against preda

What are Timbergen's 4 levels of analysis (proximate and ultimate questions)?

Evolution, Development, Mechanism, Adaptation

Describe the potential path of evolution for pennaceous feathers used in flight.

Hollow tube: likely initially had a sensory function.

Barbs: branching of the tube, has slight thermoregulatory function

Rachis/Barbules: addition of more elements for stability, rigidity, and better thermoregulation.

Hooks on barbules: further development for rigidity

Asymmetry: help with lift for flight

What is required to enable flight?

Strong wings, but light body. Fusion, elimination, and pneumatization of bones

Morphological adaptations like the keel and sternum, or wing musculature

Reallocation of body mass to legs

Cambering of wing: asymmetry required to create pressure differential below and above the wing

Angle of attack: leading edge tilted up to capture more air under wing without causing turbulence

Alula and coverlets allow for better control of vortices (reduce turbulence

What are some supporting statements for the two theories on the evolution of flight?

Ground up:

- WAIR: wing assisted incline running.

- Toe structure in historical flyers did not have the anisodactyl structure like most tree-dwellers today

- Archaeopteryx, thought to be a transitional species between terrestrial theropods and modern birds, had similar posture to ground dwelling birds.

Top down:

- Claw structure suitable for climbing

- Gliding is more efficient than taking off from the ground.

- Presence of asymmetrical feathers would help bird generate lift and glide more effectively

What is the difference between behavioural thermoregulation and physiological thermoregulation?

Behavioural thermoregulation: changes in behaviour to make use of environmental factors to cool/warm body. (ex. basking, orientation to wind/sun, changing body shape/colour)

Physiological thermoregulation: changes within the body to improve heat loss/retention. Typically involving the dilation of blood vessels, increasing heart rate, or adjustment of metabolic rate.

What are evolutionary advantages of endothermy? What are the requirements to be able to sustain it?

Advantages: Ability to be independent from the environment. Exploitation of new niches otherwise not physiologically possible to survive in. Ability to perform high energy tasks more effectively.

Requirements: A constant source of heat (metabolism, digestion, muscle activity), insulation, turbinates (specialized epithelium at surface of gas exchange to recover water and heat from exhaled air)

What are the five hypothesis for endothermy?

Niche expansion model

Thermoregulatory model

Aerobic capacity model

- Natural selection of locomotory activity also promoted increased aerobic capacity. Max metabolic rate and basal metabolic rate is genetically correlated and increased in parallel.

Parental care model

- Endothermy evolved as a by-product for selection for parental care

Assimilation efficiency model

- Parental care required increased daily energy expenditure which increased food consumption and and energy assimilation from the food. Endothermy side effect of increased number of mitochondria and membrane leakiness

What evidence may suggests that heterothermy in hummingbirds is ancestral?

Looking at body size and metabolic rate, dinosaurs were found between endotherms and ectotherms, implying that they may have been heterotherms.

Given that, the most parsimonious distribution of torpor and heterothermy would imply that it is an ancestral trait instead of one that derived independently multiple times.

What is regional heterothermy and how does it work?

There are three types of regional heterothermy, based on where the heat generating tissue is found. Systemic (aerobic red muscle), visceral (viscera including stomach), crainial (brain and eye).

Utilization of the rete mirabile and countercurrent exchange to reduce heat loss

What is the importance of the microbiome and heath?

Important for early development, shape host physiology, shapes and extends phenotype, facilitates rapid adaptation and acclimation, important for proper functioning health.

What are arguments for and against de-extinction?

De-extinction can be a useful tool in conservation. Increasing the genetic diversity of endangered animals or working on bringing back keystone species can potentially have positive effects on our ecosystem. However, we must be very careful with this technology, it is easy to overlook factors that may result in negative consequences that were not predicted for.

What are arguments for and against use of GMO?

GMO is important for human health, economics, and the environment. However, safety is key, having proper regulation and reputable companies conducting quality tests is important. GMO can also have a negative impact on the environment through indirect effects on bordering species, or escape.

What are arguments for and against use of animals in research?

Animals provide with a better physiological model to study on. However, a lot of times animal trials don't lead to successful human trials. Efforts should be placed on developing other tools that are more effective and accurate to human physiology. Animals are very crucial, and especially in cases to study the animal itself.

What are the basic forms of locomotion?

Legged, Limbless, Rolling

What are the differences between a sprawling and erect posture

Sprawling: found in reptiles, ancient, and ectothermic animals. Torso slung between legs. Improved balance, can withstand large torsional load. Developed chest and leg muscles required to maintain.

Erect: found in mammals, birds, and some dinosaurs. Torso is balanced on the limbs. Leg skeleton is not as robust as legs of sprawlers. Majority of movement is derived from limb muscles.

What are the five locomotory specializations and what are some key characteristics of them?

Cursorial (running): Speed is dependent on stride length and stride rate. Stride length can be optimized by having longer distal limbs, reduction or loss of clavicle, differing foot posture. Stride rate is optimized by having shorter increasing number of joints (rising onto toes), decreasing limb inertia, and reallocating muscle mass more proximally. Other adaptations include dorso-ventral flexion of the spine to increase stride length and force generation. Some animals like horses also have very developed tendons that conserve elastic energy and help maintain muscle integrity.

Scansorial (climbing): Enhanced cerebellar (motor function center) capacity, frictional effects, claws, prehensile tail, suction. Most scansorial animals evenly distribute their muscle with the exception of bats who have majority of their muscle in the front limbs and chest (for flight).



Saltatorial (hopping): bipedal hopping is pronounced in many prey species. Forelimbs tend to be shortened and generalized for feeding or grooming. Other adaptations include: stiffening of spine to resist whiplash, high elasticity in hind limb ligaments, and a long counterbalancing tail. Advantages of saltatorial motion include: rapid acceleration and ability to rapidly change directions. Likely evolved to allow exploration of more niches, escape from predators, and increase the hours of activity in a day (since they can dodge better).

What are the two main characteristics of horses mentioned in the guest lecture? Why are they important in how horses function?

Barrel shaped trunk: eat grass which has cellulose that requires gut bacteria to digest. Horses are hind gut fermenters. To support the gut, vertebrae must be more rigid (cannot use flexion of spine like cheetahs to extend stride length).

Short skinny legs: legs are built for speed, stamina, and endurance. To maximize speed, legs are lengthened and the collar bone is reduced. The pivot point of the leg is now raised to be higher on the shoulder blade allowing muscles attached to the shoulder blade to be recruited to power movement. Foot poster has also changed to lengthen leg, a modified nail bears most of the weight and horses have a relatively shorter humerus to lower leg limb lengths. Inertia is reduced by reducing the mass distal to center of rotation by redistributing weight. Loss of toes also reduces lower mass while maintaining structural integrity Use of tendons and ligaments as springs also allows horses to take advantage of gravitational energy and recover energy from their own strides. Also this protects muscles from rupture by taking some of the stress off. The tendons in knee and ankle are locked together in a reciprocal manner to act as more springs as well as to allow more muscle recruitment.

What are some constraints on body size?

Physiological: metabolic limit to how much energy they can generate from their environment.


Resource availability: how much food is available at the time of growth

Biomechanical: physics of supporting a larger body size

What is Cope's rule and what are some hypothesis' for this trend?

Cope's rule: Lineages tend to increase in body size over the course of their evolution


- Sampling artifacts: it is easier to find larger animals

- Organism level selection for larger body size (but evidence for this is only on a microevolutionary scale, on a macroevolutionary scale, there was directional selection on body size over all three levels of fitness)

- Bounded increase in variance and directional speciation. Larger animals less likely to get larger, but small animals they can really only get bigger. More "space" to fill in the large direction if you start out small.

- Byproduct of another trend: Thermal niche expansion (larger animals tend to be found in colder environments)

What is Allen's rule and give an example of a group of animals in which this occurs.

Allen's rule states that animals get rounder and their appendages get shorter in colder climates. for example, comparing polar bears to grizzly bears, polar bears have shorter snouts and small ears.

This was also tested in lab mice, where tail length was seen to differ significantly between temperature treatments. However these may have been due to temperature influencing proliferation rate.

What is Bergmann's rule and explain how it applies (or does not apply) to ectotherms vs endotherms.

Bergmann's rule is the idea that larger sized species are more likely to be found in colder environments. This was thought to be driven by thermoregulatory capacity where larger animals have less SA to loose heat from.

However, this is the opposite case for ectotherms. The higher the temperature, the larger the ectotherm. This was likely to be due to temperature influencing growth rate. This has implications for fish since they may be reaching sexual maturity at a younger age (and thus a smaller size) which could be reducing the overall size of fish (or it could be due to selective removal by fisheries)

What is thermal niche expansion?

Thermal niche expansion is the hypothesis that the ability for an organism to thermoregulate either regionally or entirely, allows them to exploit new niches that they would otherwise have had trouble surviving in.

How has climate changed influenced the body size in endotherms?

Increase in temperature, and lack of extreme weather allows smaller individuals to survive and give birth to smaller young, however this is risky since they may be susceptible should a storm occur.

Food quality: animals aren't able to achieve the original size due to low nutrients. Not totally supported by nutrient level, but the activity level in goats did differ based on temperature. (too hot, less foraging)

How does the Island rule apply to gigantism as well as dwarfing in species?

Island rule states that when colonizing islands, species will either get larger or smaller depending on ecological factors.

Resource limitation: Decrease in size over time.

- Gestation time (if not enough resources, cannot gestate for a very long time)

- Generation time (smaller animals have shorter generation time)

- Thermoregulation (applies to warmer climates where loss of heat is easier in smaller species since they have more SA)

Predation release: Increase in size over time.

- Larger predators die (or are absent), smaller organisms can get larger

- Resource storage (less risk= more able to cache)

- Travel capacity (no predators, can exploit new areas with less danger)

- Competitive ability/ founder effect (organism that first arrives would have the most time to exploit resources and gain the higher footing. Have longer to "grow" in the new territory)

- Sexual selection (if predation is not much of a risk, larger more elaborate displays are more likely to appear)

What are the hypothesis of the Lilliput effect and how may the skew perception of how body size changes?

Lilliput effect refers to the reduction in body size after a mass extinction which may explain the trends seen in Cope's and Bergmann's rules regarding body size change.

Has 4 hypothesis:

- Survival of small taxa: larger animals tend to be the ones that go extinct

- Selective diversification after extinction and a perceived increase in smaller organisms

- Difficulty of finding larger organisms that may be more scarce, harder to locate.

- Miniaturization after extinction event. Smaller organisms have more room to survive, so even the larger organisms become smaller.

What is the importance of testosterone and dihydrotestosterone?

Testosterone and dihydrotestosterone are key in differentiating between male and female phenotypes. T is converted into DHT by 5 alpha reductase. DHT is more potent than T and is responsible for development of external male genitalia and other male phenotypic effects. The inhibition of the 5 alpha reductase pathway will result in intersex individuals (ex. Semenya)

Some costs of testosterone include reduction in parental care and immune suppression.

Hormone function can vary between species (ex. in some species DHTA drives aggression instead of testosterone, or that there is decoupling of testosterone and territoriality)

What role does DHEA play in the stress response in song birds?

DHEA is a prescursor to important hormones like testosterone and estradiol.

It was thought to be an anti-stress hormone.

DHEA may have a neuroprotective effect in the song center of the a songbird brainduring stress exposure. Saw that with the treatment of DHEA, the HVC (area in bird brain for song production and learning) volume, number of neurons, and number of new neurons increased while the opposite happened with corticosterone. The treatment involving both had no significant difference from the control

How does the endocrine system control behaviour?

Endocrine operates on an input, integration, and output model. Input from the physical or social environment is integrated in the CNS or endocrine glands and results in changes in behaviour, physiology, phenotypic plasticity

What is the differences between the two types of reproductive strategies: Income breeding, and Capital breeding?

Income breeding: Mother relies on current food supply to power the most expensive part of reproduction, lactation. So, conception typically occurs one gestation period before the annual food peak.

Capital breeding: Mother relies on stored food to power lactation. Conception occurs as food abundance begins to increase.

Also cases of migratory birds using both, where a portion of their reproductive process that relies on stored energy from wintering sites, and also from breeding sites.

What are the different types of seasonal rhythms and how did seasonal rhythms come to be?

Type I rhythm: mixed input, both exogenous and endogenous factors influence. ex. reproductive cycle.

Type II rhythm: endogenous rhythm. Not influenced by environment.

Type III rhythm: exogenous rhythm. Entirely based on environmental conditions.

These were thought to be controlled by changes in melatonin and cortisol.

What experimental conditions must be met in order to establish a hormone-behaviour relationship?

1: removal or hormone abolishes behaviour

2: restoration of hormone reinstates behaviour

3: changes in hormone concentration is associated with changes in behavioural intensity

What are the two mechanisms of hormone action? Provide examples of these two mechanisms in action.

Organizational effects: Long term, irreversible. Occurs during critical periods of development. Has permanent effects on adult physiology and behaviour. (ex. hormonal environment in-utero affecting adult behaviour in mice. Next to females, i.e. less testosterone, they showed decreased aggression and increased parental care in males. In females, they were more choosy when next to females. Next to males, they had riskier behaviour).

Activational effects: Short term, reversible. Maintains behaviours in adulthood. Changes in hormone levels initiates changes in physiology. Typically acute effects of hormones. (ex. oxytocin exposure triggering maternal behaviour in animals. This however, only occurred when stimulating oxytocin receptors in the left auditory cortex, thought to be connected to distress calls by the pups) (ex2. Prairie vole vs Montane vole w.r.t. vasopressin (AVP) influencing pair bond formation and monogamy. AVP receptors in the nucleus accumbens and ventral pallidium promoted formation of pair bond when AVP was released. AVP receptors were not present in montane voles whom did not form pair bonds.)

What are some examples of behaviour controlling hormone production?

Challenge hypothesis: hormones influence behaviour, but the outcome of the behaviour can also influence hormone production.


- Stimulated territorial intrusion elicited aggressive behaviour, but testosterone levels remained elevated after challenge was ceased.

- Fans of winning teams had increased levels of testosterone, while fans of losing teams had lower.

- Mice that won previously were more likely to win again. When this was simulated in california mice, mice that won and were given testosterone performed much better than those that only won, or only were given saline.

Use the example of protogenous fish to explain how brain controls behaviour and vice versa.

Protogenous fish are fish that are able to change sex from male to female. These fish often live in harems and males often act aggressively towards females. This act of aggression tends to inhibit aggressive behaviour in females as well as influence production of hormones in the fish.

If the male is removed from the harem, the largest female will begin to act aggressively, like the aggressive male (within hours). Within days, they adopt the alpha male phenotype.

11-ketotostosterone (KT) is a potent androgen in fish. there is only one enzyme that converts testosterone to KT. Aromatase is important in the conversion of testosterone to estradiol (E2). The balance between expression of KT and E2 is dependent on level of aromatase. High levels of aromatase means testosterone gets shuttled down the E2 pathway. Low levels means testosterone is shuttled down the KT pathway.

The change in brain of large female occurs after the larger females begin to act aggressively towards the smaller females. It is the first change in brain aromatase activity that stimulates changes in gonads that ultimately results in the large male becoming the alpha male.

What is the HPA axis and how does it react to stress?

HPA axis is the hypothalamus, pituitary, adrenal cortex axis. When stimulated, the hypothalamus releases corticotropin releasing hormones stimulating the anterior pituitary release adrenocorticotropic hormone, stimulating the adrenal cortex to release cortisol. All later steps negatively feed back to control the stress response.

This axis is highly conserved across vertebrates and all result in the release of glucocorticoids (corticosterone or cortisol)

If stimulated by an acute stress response, HPA axis results in:

- mobilization of energy stores to fuel fight or flight response

- increased heart rate

- inhibited reproduction

- inhibited digestion

- increased analgesia

- a short term and adaptive response.

Chronic stress on the other hand results in:

- fatigue

- hypertension

- impotence, anovulation

- peptic ulcers

- depression

- ultimately long term and costly responses

How does predation stress influence phenotypic plasticity in amphibian tadpoles?

Predation stress in tadpoles resulted in shorter and fatter tails. This was also seen in tadpoles that were given corticosterone, and the behaviour was absent in animals given a corticosterone synthesis inhibitor.

Describe how selection pressure differs in orange and blue morph tree lizards based on stress physiology.

Orange morphs in general have a longer lifespan. However, their testosterone secretion differs in low stress and high stress conditions. In low stress, they secrete high testosterone and have moderate reproductive success. In high stress situations, they secrete low levels of testosterone and have no reproductive success.

Blue morphs on the other hand have short lifespan. However, their testosterone secretion is not influenced by stress and have high reproductive success no matter the stress level.

Under low stress conditions, the orange morph and the blue morph have similar reproductive success and the tree lizard will experience disruptive selection.

Under high stress conditions, the orange morph has no reproductive success and the population will experience directional selection towards the blue morph.

How can stress of a mother affect the stress physiology of her offspring?

There can be direct effect of maternal stress on the fetus as well as the germline cells of the fetus depending on where in pregnancy the mother was stressed in.

If the mother was already pregnant and stressed, the germline cells of the fetus will also be affected which will mean that direct effects can last up to the third generation.

How does prenatal stress effect glucocorticoid receptor expression in rat offspring and what behavioural consequences does this have?

Early life stress changes behaviour as adults. High maternal glucocorticoids result in offspring with low numbers of glucocorticoid receptors, high levels of glucocorticoid expression, hypersensitivity to stress, anxiety as adults, and low maternal behaviour.

Low maternal stress results in the opposite of the above.

Stress induced changes in the maternal gut can also negatively impact offpsring. Vertically transferred microbiome can from mother to young is important for the ultimate composition of the offspring's microbiome.

Prenatal stress also manipulated pup growth rate. High levels of prenatal stress resulted in increased pup growth rate.

What is the difference between silver spoon vs environmental matching hypothesis?

In the silver spoon hypothesis, it is always better to have less stress exposure.

In the environmental matching hypothesis however, there is greater fitness if early life stress matches the adult environment stress conditions.

What are the benefits of trichromatic vs dichromatic vision and what likely drove the selection for such a trait?

Trichromatic vision allows colour perception. It is seen in African/eurasian monkeys and it improves recognition of contrast in the environment and likely arose in environments where color perception is important in foraging.

Dichromatic vision is found in central and south american monkeys. These monkeys are unable to perceive colour, however they are much better at perceiving shapes. This trait likely was selected for in environments where shape is important for foraging.

How is vision different underwater and what might have brought upon these changes?

In aquatic eyes, the lens is spherical and instead of being deformed by the muscle, it is shifted wrt to the retina to focus the image.

Colour pigments in the eyes of fish are plastic, fish can increase/decrease their ability to see infrared light in murky waters.

Most light is not able to penetrate in deep water, fish that live in these limited light environments often have developed biofluorescence which allows them for communication in low light conditions.

What are the three potential drivers for the evolution of sensory systems?

A changing animal environment: positive selection to detect novel stimuli, changes in odour or pheromone release, changes in density of predators or prey.

Animals only sense a subset of their environment: they have a lot of room to developed enhanced sensing. There is selective advantage if an animal is better at sensing their environment. Subset of stimuli present also changes, different forms may be better for different situations.

Animals use sensory cues as information proxies: typically animals do not detect salient environmental features, but infer them from specific stimuli. Since salient cues change, so will the sensory cues.

What are three examples of physiological specializations that allow animals that rely heavily on scent to perform well.

Snakes: have a vomeronasal organ (aka jacobson's orgaon) that connects to the brain where they deposit scent particles collected by the tongue. Used to provide directional information.

Enhanced development of olfactory epithelium in noses of mammals. More development typically means more complexity of receptors.

Larger olfactory processing centers wrt rest of the brain. Important in processing of scent information.

What are the two primary hypothesis for directional sensing?

Cryptochrome: a photoreceptive protein that is found in many vertebrates, but mainly bird eyes. Sensitive to blue light. Once activated by specific wavelengths, unpaired components of this protein spin in certain directions influenced by the magnetic field.

Iron oxide (magnetite): iron based substance that can be magnetized and aligned in linear arrangements. Expressed in the beak of birds, snouts of trouts, and the bodies of eastern newts.

The coupling of these sort of receptors with other sensory cells is hypothesized to provide animal with ability to navigate. (i.e. coupling with stretch activated ion channels)

Alternatively, these two hypothesis may be combined in application. There is evidence of a MagR gene that binds iron and forms a complex with cryptochromes.

What are the differences between the "headgear" of deer, cows, giraffes, and pronghorns?


- Made of a single bone, no keratin layer (once fully mature)

- Growth and shedding is stimulated annually by hormones

- Only found in male cervids.


- Living bone inside a keratin sheath

- Fused to skull by connective tissue

- Present in males and some females

- Grows throughout life, nothing is shed

- Found in the bovid family


- Only found in giraffes

- No keratin sheath around bone, but is covered with a fuzzy epidermis


- Similar to bovid horns, but keratin sheath is shed yearly while the bone remains.

Describe the difference between the morphological and molecular phylogeny of antler loss in the mouse deer and musk deer. Which one is more parsimonious and why?

In the morphological phylogeny, there was hypothesized to be 4 independent origins of antlers. In the molecular phylogeny, there was 1 origin and 1 loss of antlers.

The molecular phylogeny is more parsimonious since it requires the least number of changes.

What is the difference between toxins and venoms?


- Must be ingested/passively encountered

- No specialized mechanism to deliver to the recipient


- Housed and produced in specialized structures

- Associated with a delivery device

- Active delivery to recipient

- Typically a blend of different compounds

Explain how the variation in snake venom between the diamond back rattle snake and the eastern coral snake may have arose.

Diamond back:

- Extensive geographical variation in venom

- Local adaptation to environment, likely as a result of co-evolutionary arms race with prey

- Difficult to produce an antivenom for this since their venom i composed of a wide array of toxins

Eastern coral:

- Almost no geographical variation in venom

- Recent invader, perhaps it hasn't had the time to locally adapt

- Easier to develop an antivenom for

What are a few different types of venoms?

Neurotoxins: Inhibit acetylcholine release, resulting in inhibition of neural impulses. Can result in paralysis and respiratory failure. There are two forms of paralytic neurotoxins: spastic paralysis (all contract) or flaccid paralysis (all relax)

Myotoxins: Depolarize muscles and cause necrosis in muscle tissue.

Hemotoxins: can be haemolytic, anti-coaglant, or pro-coagulant.

What is TTX and what are some examples of it being used?

TTX blocks voltage gated sodium channels.

- Causes membrane depolarization triggering muscle contraction.

Fugu pufferfish and california newts have developed TTX resistant sodium channels.

Fugu concentrate TTX in the liver and the roe, it is a sushi delicacy that derives euphoria, numbness and tingling to the consumer. But it also has later effects like nausea, paralysis, respiratory failure, inability to swallow, loss of brain stem reflexes.

Newts have developed a level of super toxicity that is beyond what is required to kill predators. Thought to have evolved sothey can kill their predators earlier and earlier. TTX is expensive to make, so they must derive even greater fitness benefit from being supertoxic.

What things must be tested to determine if it is a substrate for natural selection?

Is there:

- Variation

- Heritability

- Differential reproductive success

What are typical responses for an animal to adjust to climate change and altered thermal niches?

Shifting to a more favourable environment

Behavioural plasticity

Adaptations (physiological plasticity)

However all these are limited to time and environmental factors. Additionally, things like range expansions can result in the out competition of native species.

How are humans impacting extinction rate?

There is already an intrinsic rate that exists, however humans are accelerating the process. There is higher biodiversity near the equators, which may be why it has a higher intrinsic extinction rate. However most of human development is also occurring around those areas, which means those areas are even more so at risk.

What are some examples mentioned in class regarding the influence of climate change on survival of certain species.

Ex. Rodents and creosote tree:

The liver's ability to metabolize creosote tree toxins decreases with increasing temperature. It is seen that mice subject to warmer temperature treatments were unable to maintain their body weight due to lack of feeding.

Ex. Saiga antelopes:

Unexpected late cold weather caused 70% of the population to die since the increased glutocorticoids release in response to the stress resulted in a disturbance in their gut microbiome. Pasteurella, which is normally harmless in small quantities, proliferated during this chronic stress state and killed the hosts

Ex. Phenological mismatch

Fitness variation in a population is influenced by the timing of breeding and the timing of a species that is important to the survival of the focal species. For example, caterpillar abundance wrt to chick rearing.

Missing breeding season due to influence of anthropogenic artificial light

What is the difference between a proactive and a reactive response to a perceived stimulus in the environment?


- Aggressive and bold behaviour

- Rigid, and routine-like behaviour

- Low stress response

- Less sensitive to environmental change

- Less able to cope with environmental change

- More fit in a constant or predictable environment


- Cautious and shy behaviour

- Flexible behaviour

- High stress response

- More sensitive to change

- More able to adapt to change

- More fit in a changing environment

Why is the arctic more affected by climate change and what are some examples of mismatch timing influencing survival of arctic species?

Climate change occurs more rapidly at the poles. This can mean great differences between timing wrt cues on wintering grounds vs. breeding grounds. Polar species were also less able to acclimate to changes in temperature.

Colour changes of fur from white to brown in circumpolar species is impacted by changes in show cover due to climate change. The mismatch is getting more and more pronounced and as a result, these species aren't able to camouflage.

The rock ptarmigan has been seen to cover its white fur with dirt to increase cover, and it fares slightly better than the hares.