POSC 333 Test #2

Activational effects

-Activational effects: occur in adulthood and tend to be transient ∗ Lasting only as long as the hormone is present at high levels ∗ Involve subtle changes in previously established connections ∗ i.e. slight changes in neurotransmitter production or release along established pathways ∗ Not involved in gross reorganization of neural pathways

Adults vs. juvenile responses to sex steroids

-Activational hormones: sex steroids in adults have only a transient activational effect on copulatory behavior ∗ By adulthood, the nervous systems of adult males and females have already differentiated ∗ The organizational effects of early steroid secretion have long since occurred ∗ Mature brains are not capable of responding to hormonal signals of the opposite sex

Hormones affect salmon migration

-Adult Atlantic salmon leave the ocean and return to their natal stream to spawn in the fall ∗ Laying thousands of large, fertilized eggs in a gravel depression called a redd ∗ Parr: very young salmon, 5 cm long, with vertical marks on their sides for camouflage ∗ Smolt: 15 cm long fish that undergoes smoltification, which prepares them for migration to the ocean ∗ Dramatic changes in physiology, morphology, and behavior occur during changes from parr to smolt ∗ To prepare for migration

Perception of biologically relevant stimuli

-An animal bombarded with stimuli from its environment can detect only a limited range -It ignores background "noise" -An animal's sensory system is selective -It provides only information vital to the animal's lifestyle And reproductive success -Receptors are "tuned" to detect biologically relevant stimuli -ex: through natural selection, fish in different habitats have eyes sensitive to the most common wavelength of light in that habitat

Sound localization

-An organism must be able to locate the source of sound i.e. the sound of a potential mate or a predator -What properties of sound enable its source to be located? 1. Its intensity: it is louder when the receptor is close 2. Binaural comparison: both ears are used in locating sound 3. Timing at the onset of sound: sound begins and ends sooner in the ear closest to the source 4. Timing during an ongoing sound: differences in the phase of the sound wave reaching each ear -The extent of the phase difference depends on the sound's wavelength and the distance between the ears -If the wavelength of the sound is twice the width of the head: The peak and trough of a wave arrive at each ear separately The sound can be easily localized -If the wavelength of the sound equals the head width: the phase of the sound wave is the same in each ear and the sound is difficult to localize

Autonomic Nervous System

-Can be divided into 2 divisions: -Sympathetic Nervous System: "Fight or Flight" -Parasympathetic Nervous System: "Rest and Digest" -These 2 systems are antagonistic (go against each other) -Typically, we balance these 2 to keep ourselves in a state of dynamic balance.

Antihormones

-Cannulation techniques administer tiny amounts of hormone to specific regions ∗ Antihormones: drugs that temporarily and reversibly suppress the actions of specific hormones ∗ The antihormone RU486 blocks projesterone receptors (mice stop killing kids)

Constant (opportunistic) reproductive pattern

-Characteristic of species in harsh environments (i.e. deserts) ∗ Suitable breeding conditions occur suddenly and unpredictably ∗ Indesert-dwellinganimals, reproduction is initiated by rainfall ∗ While waiting for breeding conditions ∗ Species maintain large gonads, mature gametes, and high circulating levels of sex steroids -Zebra finches live in Australia where there is drought but as soon as it rains that means there is food to be had so need to be ready to breed

Communication (Test-label or draw pic)

-Communication between neurons is not typically a one-to-one event. 1. Divergence: Sometimes a single neuron branches and its collaterals synapse on multiple target neurons. 2. Convergence: A single postsynaptic neuron may have synapses with as many as 10,000 postsynaptic neurons. -Can you think of an advantage to having convergent and divergent circuits? some sensations get stimulated at once and cause one reaction, or one cause to get reaction

The organizational effects of gonadal steroids on sexual behavior

-Development of a "male" brain requires testosterone around the time of birth ∗ In the absence of testosterone, a "female" brain develops ∗ The effects of perinatal testosterone on adult sexual behavior are organizational ∗ Occur early in life and involve permanent structural changes in the brain

Electrical and chemical synapses

-Electrical: less common, fast transmission, connected by tubules so ions flow directly -Chemical: larger space, slower transmission, neurotransmitters, calcium ions

Steroid hormones have activational effects on sexual behavior in rats

-Female rats with high estrogen and progesterone levels display feminine sexual behaviors when near a sexually active male ∗ But not when levels of these ovarian hormones are low ∗ Removal of the testes in an adult male eliminates copulatory behavior ∗ Steroid hormone effects on sexual behavior are activational ∗ Estrogen, progesterone and testosterone exert their effects by activating existing neural pathways ∗ In contrast to permanent changes in sexual behavior caused by testosterone during the neonatal period

Adjusting to the environment

-Habitats of species provide different mating opportunities ∗ Associations between gonadal hormones and sexual behavior varies among species ∗To allow the greatest number of surviving offspring ∗ A diversity of reproductive patterns exits in: ∗ (1) production of gametes ∗ (2) secretion of sex steroids by the gonads, ∗ (3) timing of mating behavior ∗ Three general patterns of reproduction exist in vertebrates: associated, dissociated, and constant (but other patterns exist)

The hormonal basis of helping at the nest

-Helpers: nonbreeding animals that assist the breeding pair in rearing young ∗ Providingfoodandprotectingtheyoung ∗ The evolutionary causes of helping: helpers get some of their genes into the population even though they don't breed ∗ Florida scrub jays live in small groups in south central Florida scrub oaks ∗ Helpers:offspringofthebreedingpairfroma previous year who remain on the territory and help raise siblings -Helpers are physiologically capable of reproduction ∗ Their testes and ovaries produce hormones ∗They can gather enough food to breed successfully ∗ Levels of the stress hormone corticosterone (suppresses production of reproductive hormones) equal breeders' ∗ Prolactin levels increase through the breeding season, initiating parental care ∗ Females produce more prolactin than males ∗Cues from the nest, eggs, and nestlings stimulate production ∗ Helpers have low prolactin levels because breeders won't allow them near the nest until the young have hatched -There is a relationship between a helper's level of prolactin and the feeding score (a measure of how much a bird fed the nestlings) ∗ Feedingscore=0:helpers didn't help ∗ Prolactinlevelsofthe helpers that did help are much higher

A reciprocal relationship between hormones and behavior

-Hormones can activate specific forms of behavior - And behavioral stimuli can induce rapid changes in hormone levels ∗ Sexual stimuli can trigger a rapid increases in androgen levels ∗ In the marine toad, androgen levels increase with time spent in amplexus ∗ Suggesting that mating behavior induced the hormonal response rather than vice versa

Hormonal suppression of behavior

-Hormones can also rapidly and selectively suppress a behavior ∗ Androgens and vasotocin mediate amplexus in newts ∗ Males clasp a female while she becomes sexually receptive ∗ What happens if a male in amplexus detects a predator? ∗ Does he continue with amplexus and "hope for the best?" ∗ Or terminate the behavior and seek a safe hiding place? ∗The hormone corticosterone suppresses amplectic behavior ∗ Reducing the activity of neurons active during amplexus ∗ It acts via a receptor in the membrane of neurons, not by altering gene expression and protein synthesis

Visual experience increases auditory map precision

-If the auditory map conflicts with visual input owls trust their vision over their hearing -Normally the auditory space map and visual space map in the are aligned -If the two maps are misaligned, the owl adjusts the location of sound to match its distorted visual map

Chemical messengers

-In an elaborate system of internal communication ∗Hormones and neurohormones exert effects at the cellular level ∗ Altering metabolic activity or inducing growth and differentiation ∗Changes at the cellular level can eventually influence behavior ∗Chemical signals function within an individual to influence its behavior, morphology, and physiology ∗ A hormone can have diverse effects within an individual ∗Some chemicals function in communication between animals ∗ In arthropods, insects, crustaceans, spiders, and scorpions

Steroid hormones influence behavior through organizational effects

-In organizational effects, steroids organize neural pathways responsible for certain patterns of behavior ∗ Occur early in life - just before or after birth ∗ Are permanent: the brain or cells change structurally ∗ i.e. in the responsiveness of neurons to steroid hormones ∗ Can have organizational effects on nonneural systems ∗ i.e. changes to the male western mosquitofish fin and its skeletal supports cause sex differences in mating behavior ∗ Also activate neural systems responsible for mediating specific patterns of behavior

Hormones influence development of singing behavior in birds

-In the zebra finch, sex differences in the brain nuclei that control song are established around the time of hatching ∗ Soon after hatching, the brain's hormonal environment establishes sex differences in adult singing behavior (males sing and females do not) ∗ The steroid hormones involved in the early masculinization of the zebra finch brain are neurosteroids, not gonadal steroids

message of a neuron

-Ion movements are responsible for a neuron's message -Action potential: an electrochemical signal caused by electrically charged atoms (ions) moving across the membrane -Ions cross a cell's membrane either by the sodium-potassium pump or ion channels -Passive channels are always open and triggering signals open ion gated channels (triggers are neurotransmitters, changes in membrane potential, or changes in calcium ions) -The pump uses cellular energy to move sodium ions (Na+) outward while transporting potassium ions (K+) inward -An ion channel is a small pore through a cell's membrane -Ions move across an open channel in response to -A concentration gradient: ions move from a highly concentrated area to an area of lower concentration -An electrical gradient: ions move away from an area with a similar charge and toward an area of the opposite charge

Suspension Feeding

-Many aquatic species remove small suspended food particles from the surrounding water • Some species sieve water and strain food • Others trap particles on sticky surfaces of mucous • Blue whales weigh over 100 tons yet survive on tiny shrimp-like creatures (krill) • The annelid worm creates a mucous net in its burrow, rolls into a ball and swallow 1. Sessile/Stationary: take food that comes their way 2. Move: whales • Some adjust their filtration pattern to choose particular types of particles •Dabbling ducks strain food through filters on their bills • Feeding on different sized particles by changing their bill's position

Dissociated reproductive pattern

-Matingbehavioriscompletely uncoupled from gamete maturation and secretion of sex steroids ∗ Gonadal activity occurs after rall breeding activity has ceased ∗ Gametes are produced and stored for the next breeding season ∗ Gonadal hormones may not play a role in the activation of sexual behavior

Bats and moths

-Nervous systems gather and process information about the source of sounds to produce adaptive behaviors -Escape behavior by prey -How a night-flying (noctuid) moth escapes from an echolocating bat -Each ear has two auditory receptor cells each tuned to the frequencies of the echolocation calls of species of bats living in their vicinity -The A1 cell receptor cell is extremely sensitive and it begins responding when the bat is still at a distance Warns the moth there is a hunting bat in the vicinity -The A2 receptor cell responds only to loud sounds coming from a nearby bat -The moth responds to bat sounds long before the bat detects the moth -The moth can decode incoming data, to detect both the presence and location of the bat -It can determine if the bat is: Near or far, On its left or right side, Above or beneath, In front or behind

Why nervous system in animals?

-Nervous systems have evolved so an animal can quickly Detect pertinent events in its environment -Choose appropriate responses to events -Coordinate the parts of its body to execute its responses 1. Sensation: Monitors events occurring inside and outside the body. These changes are known as stimuli and the cells that monitor them are called receptors. 2. Integration: The parallel processing and interpretation of sensory information to determine the appropriate response. 3. Reaction: Motor output. The activation of muscles or glands; typically via the release of neurotransmitters (NTs)

Birth and death of nerves

-Neurogenesis: the birth of new neurons Can occur even in older animals -Brain changes that occur with behavioral changes include the birth of new neurons and death of old neurons -Neurogenesis regularly replaces neurons in a bird's brain -Song system: discrete but interconnected centers in the songbird's brain that allow learning and production of songs -The size of two song centers (HVC and RA) increase and decrease seasonally, along with the amount of song learning -After an animal has begun to master a task, the neurons that have not made connections with other neurons die -Cell death is necessary for the survival of the earlier born neurons and for an increase in neurogenesis, which increases the pool of new neurons -The number of new neurons in the hippocampus also changes with spatial learning during food storing and retrieval in birds

Neurons are classified based on function

-Neurons = nerve cells -Sensory (afferent) neurons: carry signals from a receptor organ at the periphery toward the central nervous system. In vertebrates, the brain and spinal cord. In invertebrates, the brain and nerve cord -Efferent (motor) neurons: carry signals away from the central nervous system to muscles and glands -Interneurons: within the central nervous system -Connect neurons to each other -Process sensory input and determine the motor response

Summation

-One EPSP is usually not strong enough to cause an AP. -However, EPSPs may be summed. 1. Temporal summation: The same presynaptic neuron stimulates the postsynaptic neuron multiple times in a brief period. The depolarization resulting from the combination of all the EPSPs may be able to cause an AP. 2. Spatial summation: Multiple neurons all stimulate a postsynaptic neuron resulting in a combination of EPSPs which may yield an AP

Studying hormone-behavior relationships: correlational studies

-Researchers look for changes in behavior that parallel fluctuations in hormone levels ∗ Not as conclusive as experimental work because there is no evidence of causation (correlation doesn't equal causation) ∗ One correlational study examined the relationship between testosterone levels and aggressive behavior in male song sparrows

Scent-marking

-Scent-marking: the act of strategically placing a chemical mark in the environment ∗ Many mammals apply urine, feces, or secretions from special scent glands on the digits, legs, chest, belly, head, or in the anal canal ∗ Many mammals have scent glands at multiple locations ∗ Scent marks convey information about individual identification, age, and reproductive state ∗ Establish and maintain territories and breeding relationship -ex: urine marking in dogs: usually sexually dimorphic (female typically squat and males lift legs); testosterone not need for lifted leg; most common close to estrous cycle

parts of a motor neuron

-Soma: cell body that contains the nucleus -Neurites: small-diameter processes -Dendrites: neurites that receive information -Axon: the single, long, neurite that transmits information to other neurons -It ends on a muscle or a gland (an effector) -Myelin sheath: the fatty wrapping around some axons in vertebrates; not continuous allowing message to jump and be faster, formed by glial cells

Associated reproductive pattern

-Some animals (i.e. the Norway rat) exhibit a close temporal association between gonadal activity and mating ∗ Gonadal growth and increased levels of sex steroids activate mating behavior ∗ Found in most vertebrates studied -Inhabit harsh environments with a predictable, but narrow, window of opportunity to breed ∗ Specific physical or behavioral cue triggers mating behavior ∗ Red-sided garter snakes range farther north than any other reptile in the Western Hemisphere ∗ The mating opportunity lasts 1 to 4 weeks ∗ Male courtship behavior is activated by increased ambient temperature following winter dormancy ∗ Not by testicular hormones -Testicular activity is minimal in male snakes during the period between emerging from hibernation and mating ∗ Five to ten weeks after males have left the den site and no longer court females ∗ The testes grow and androgen levels increase ∗ Sperm produced is stored for use the next spring ∗ Males use environmental cues, not sex hormones, to determine mating season ∗In females, changes in sexual attractivity and receptivity are mediated by physiological changes that occur as a consequence of mating

Questioning the dichotomy

-Some researchers think the distinction between organizational vs. activational effects is too restrictive ∗ Some effects produced by steroid hormones are both ∗ i.e. the production of permanent effects in adulthood ∗ Specific cellular processes uniquely associated with each type of effect have not been identified ∗ However, the traditional distinction of organizational and activational effects is still useful in categorizing hormonal effects on behavior

Sexual differentiation in the young rat

-Testosterone enters the brain - Is converted to estradiol, causing masculinization • Males develop the capacity to express masculine sexual behavior - Losing the capacity to express feminine copulatory behavior • Also, androgens masculinize the muscles of the penis and their motor neurons

Hormones rapidly change behavior

-The dynamic interactions between hormones, behavior, and the nervous system allow the behavioral state of an animal to shift rapidly and adaptively to changing environmental circumstances. ∗ Hormones allow an animal to adjust its behavior so that it is appropriate for the situation at hand ∗ Hormones, behavior, and the environment interact to generate adaptive behavior in the long term

Hormonal vs. neural communcation

-The endocrine system is closely associated with the nervous system ∗ Some hormones are made by nerve cells ∗ Neurons and hormones can work together to control a single process ∗ Neuroendocrine system: association of nervous and endocrine systems ∗ However, neural and hormonal information systems have different purposes

Individual differences in the behavior of male tree lizards

-The organizational/activational dichotomy explains differences between individuals of the same sex ∗ Individual differences are most pronounced in species with naturally occurring alternative male phenotypes ∗ Such as plainfin midshipman fish and tree lizards ∗ The tree lizard has alternative malephenotypes that differ in aggressive behavior and color of the dewlap ∗ Aggressive males have orange-blue dewlaps ∗ Nonaggressive males have orange dewlaps

EPSPs & IPSPs

-Typically, a single synaptic interaction will not create a graded depolarization strong enough to migrate to the axon hillock and induce the firing of an AP. -However, a graded depolarization will bring the neuronal Voltage closer to threshold. Thus, it's often referred to as an excitatory postsynaptic potential or EPSP. -Graded hyperpolarizations bring the neuronal VM farther away from threshold (more negative) and thus are referred to as inhibitory postsynaptic potentials or IPSPs.

Optimal foraging theory

-What is eaten and how much, is of critical importance for reproductive success. • Thus, feeding behavior should be acted upon strongly by natural selection. • Premise: Animals should forage to maximize intake rate (amount/time) of limiting resource. • Simply put: to get the most food while doing the least amount of work. • So what are the most important factors then?: Types of food and Types of location. • Food quantity and profitability. • Profitability is affected by 1. Energy gain per "unit": prey individual, berry, bite 2. Energy expended per "unit" 3. Time spent catching, handling, & processing

Developmentally fixed & developmentally plastic phenotypes

-When phenotypes are developmentally fixed, they can't change ∗ Caused by organizational effects of steroid hormones in neonates ∗Developmentally plastic phenotypes can change ∗ Behaviors change in response to environmental conditions ∗ Changes in adult hormone levels reflect activational effects ∗Relative plasticity hypothesis: developmentally fixed phenotypes rely on organizational effects of steroid hormones ∗ Developmentally plastic phenotypes rely on activational effects

Estradiol's role in masculinization

-Why doesn't estradiol in young female rats have the same effect? ∗ Estradiol levels in young females are very low ∗ An estrogen-binding protein (alpha-fetoprotein) is produced in male and female fetuses ∗ Persists in decreasing amounts during the first three weeks of life ∗ In females, it prevents estradiol from reaching target neurons in the brain ∗ It does not bind testosterone, which is converted to estradiol, and results in sexual differentiation

Hormones

-chemical substances secreted in one part of the body; responsible for physical and behavioral differences ∗ And cause changes in other parts of the body ∗ Secreted by endocrine glands or neurons ∗ Endocrine glands lack ducts and secrete their products into the spaces between cells ∗ The hormones then diffuse into the bloodstream ∗ And travel to every part of the body ∗ Neurohormones (neurosecretions): secreted by neurons ∗ Produced in the nerve cell and released at the axon tip -act within individual, between individuals or same and different sp.

Prey localization by barn owls

-good sight but it can to strike with deadly precision using sound alone -facial ruff: densely packed feathers on the owl's face focuses and amplifies sound which makes the ear more sensitive to sound from certain directions -The right ear: sensitive to high- frequency sounds from above the head -The left ear: sensitive to high- frequency sounds from below the head -Information on the timing and loudness of sounds in each ear is sent to the brain -Each side of the brain has two cochlear nuclei: -The magnocellular nucleus receives timing information that places sound on a horizontal plane -The angular nucleus receives intensity information that places sound on a vertical plane -These features of sound are processed along nearly independent pathways to higher processing stations where a map of auditory space is formed in midbrain -Where neurons respond to binaural differences, depending on the sound's location -The resulting auditory space map is transmitted to the optic tectum -An area of the brain involved in localizing and orienting to visual information

Compass Orientation

-no landmarks; may use the sun, stars, and earth's magnetic field as compasses. -ex: When immature birds of some migratory species are displaced. • They flew in the same direction as the parent group that had not been moved. They flew for the same distance -Compass orientation is indicated if an animal is moved to a distant location and does not compensate for the relocation. -can be used in: • Short-distance and long-distance navigation • First time migrants usually reach their destination without knowing where that goal is located. • Vector navigation: an inherited program that tells juveniles in which direction to fly and how long to fly. • Ex: Birds in the laboratory fly in the direction in which they would be flying if they were free. • Captive birds cease their activity at the same time as free-living birds have completed their migratory journey.

Organization of nervous system

1. Central Nervous System -the brain + the spinal cord -The center of integration and control. 2. Peripheral Nervous System -The nervous system outside of the brain and spinal cord. 31 Spinal nerves -Carry info to and from the spinal cord. -12 Cranial nerves -Carry info to and from the brain

Feeding Choices

1. Omnivory: animals eat both plants and animals • Animals are omnivorous for many reasons: • Limited amounts of a preferred food • A need for nutritional variety • Minimizing exposure to risks (predators or toxins) associated with a particular food type 2. Herbivory: plant eaters 3. Carnivory: meat eaters

Predator strategies

1. Pursuit: chase their prey (cheetah's 70mph; seabirds plunge dive) • Tracking: steering to keep the moving image in front (e.g., houseflies, beetles) • Intercepting: aiming at a place front of the prey (i.e. dragonflies) • Hunting in groups 2. Stealth: pursuit can be exhausting so stalk and rush instead • Predators choose hunting sites with good cover • Even if prey are fewer • Camouflage makes the predator hard to detect -Smokescreening: predators use environmental disturbances to camouflage their approach • Jumping spiders prey on other spiders by climbing into the prey's web (move when wind moves web) • aggressive mimicry: A predator gets close to its prey because it mimics a signal that is not avoided by the prey • And may even be attractive to it (lures-angler fish) -may mimic beneficial species: blennid fish looks and behaves like the cleaning wrasse, but it bites the gills or other soft parts of the fish -send signals to mimic: A Photuris female signals to a Photinus male and when the male lands the female eats him (not a firefly) • Another firefly may have evolved to be day-active to escape predation by Photuris 3. Traps: bubble nets by humpback whales -spiders: webs

Steps to a neuron

1. Resting potential: the charge difference across the membrane; inside is more negative than outside (Na+ is greater outside and K+ inside, lots of - inside) 2. Depolarization:Na+ enters the neuron 4. Repolarization: restores negative charge bc Na+ moves back out -hyper-polarization: enough potassium ions leave to make the cell's interior even more negatively charged than usual 5. Down the axon 6. Synapse

Peripheral Nervous System

1. Sensory Division: Sensory nerve fibers can be somatic (from skin, skeletal muscles or joints) or visceral (from organs within the ventral body cavity); pain 2. Motor Division: Conducts impulses from CNS to effectors (muscles/glands). -Somatic nervous system: VOLUNTARY; Somatic nerve fibers that conduct impulses from the CNS to skeletal muscles. (moving arms) -Autonomic nervous system: INVOLUNTARY: Conducts impulses from the CNS to smooth muscle (cardiac muscle)

How do predators detect prey?

1. special senses: Some snakes select environments that provide good thermal contrast to hunt 2. touch: Predatory sand scorpions detect a prey's vibrations as it runs through the sand; The star-nosed mole finds prey by using its nose (can detect things underwater) 3. smell: Petrels and albatrosses sniff out seafood patches scattered over vast expanses of open ocean • Dead organisms release compounds that seabirds can smell • Krill feed on phytoplankton which releases dimethyl sulfide (DMS) • Which leads seabirds to krill • Odors of krill or DMS provide an immediate way to assess the potential productivity of an area • Different species use these cues in different ways • Before they fledge, young chicks prefer particular scents 4. Electrical: Shark close to its prey, its nose directs the search • Lateral line organs detect small disturbances in the water • Even if it cannot see prey • At close range, the shark sees its prey • Sharks also respond to electrical cues from prey (seen in rays, skates and lung fish too)

Onlookers in the social environment

An animal's social environment also influences hormone-behavior relationships ∗ Behavior and hormone levels change when conspecifics are watching ∗ Male Siamese fighting fish are spectacularly colorful ∗ They build mucus-covered bubble nests at the water surface ∗ Nests attract females and are home for eggs and hatched fry ∗ Males defend territories centered on their nest ∗ Social environment (presence/absence of an audience) and territory status (presence/absence of a nest) ∗ Influence aggressive behavior and hormone levels in males ∗ Males without a nest were less aggressive ∗And had lower 11KT levels, when a female audience or noaudience was present ∗ In the presence of another male, males were less aggressive ∗ And had lower 11KT hormone levels, when both had nests

The challenge hypothesis

Challenge hypothesis: the social environment influences hormone (i.e. testosterone) levels regulating aggression and dominance ∗ Social challenge or instability increases hormone levels ∗ i.e. during territory establishment in song sparrows ∗Nonmigratory male song sparrows exhibit territorial aggression ∗ Even when nonbreeding, when testes have regressed ∗ Estradiol, not testosterone, regulates this aggression ∗ In stressful times, testosterone is too costly in terms of: ∗ Increased metabolic rate ∗ Decreased body mass, fat stores, and immune function

Hormones influence sex differences in muscles

Most mammals have sexually dimorphic muscles and motor neurons ∗ But they are absent or reduced in females ∗ Sex differences in the copulatory movements of adult rats result from early hormonal influences ∗On growth and maintenance of muscles and motor neurons ∗ Specialized muscles control copulatory reflexes in male rats ∗ These muscles are present in both sexes at birth ∗ But are completely absent in adult females, due to a lack of androgen at birth

Hormones affect muscles and motor neurons

South African clawed male frogs emit six different calls ∗ The advertisement call allows females to find males ∗ Sexually receptive females produce a rapping call ∗ Unreceptive females tick ∗ Hormone-induced changes in the muscles of the larynx results in sex differences in calling behavior

Studying hormone-behavior relationships: interventional studies

The experimenter manipulates the hormones of the animal ∗ Removes the endocrine gland (testes) ∗ Followed by hormone replacement therapy ∗ For example, testosterone regulates courtship and copulation in the male green anole ∗ What happens when the testes are removed? -Removal led to a sharp decline in sexual behavior in green anoles ∗ Administration of testosterone reinstated this behavior ∗ Unlike sexual behavior, aggressive behavior only partially depends on gonadal hormones ∗ It's also influenced by social factors such as residence status

OFT predictions

• 1. When a profitable food type is abundant? • foragers should specialize on it. • 2. When it is scarce? • foragers should be opportunistic. • 3. When food is concentrated in certain patches? • foragers should devote their time there. • Over time, foragers should tend to equalize yield over all patches.

Platypus predators

• A platypus has electroreceptors and mechanoreceptors on its bill • Giving it a three-dimensional fix on prey • A platypus hunts at night in murky streams • Closing its eyes, ears, and nostrils • It digs in the silt with its paws and bill to stir up small animals • Prey generate electrical fields, sensed by electroreceptors • Mechanical waves are sensed by mechanoreceptors on its bill

Visual cues: landmarks

• An easily recognizable cue along a route that can be quickly stored in memory to guide a later journey. • Based on any sensory modality, but is most commonly visual. • Example: • The digger wasp relies on landmarks to relocate its nest after a foraging flight.

Navigational abilities

• Animal have great strategies for finding their way. • 3 Types: 1. Piloting: ability to find a goal by referring to familiar landmarks. • The animal may search randomly or systematically for landmarks. • The guidepost may be any sensory modality (not just visual). -Magnetic cues -Olfactory cues 2. Compass orientation: Animals head in a geographical direction without using landmarks. 3. True navigation: ability to maintain or establish reference to a goal, regardless of its location, without use of landmarks.

Two magnetoreceptor systems

• Animals might have one or both types of magnetic sensitivity 1. Light-dependent: involves specialized photoreceptors. • Certain animals can see the earth's magnetic field. • Photoreceptor molecules absorb light better under certain magnetic conditions. • The amount of light absorption provides information about the local magnetic field. 2. magnetite: a magnetic mineral in animals • It orients to the geomagnetic field • Found in bees, trout, salmon, birds, and sea turtles • In vertebrates, these deposits are found in the head or skull • It can twist to align with the earth's magnetic field, stimulating a stretch receptor • In the rainbow trout, nerves contain fibers that respond to magnetic fields

A magnetic compass

• Animals respond to the intensity of the geomagnetic field • The Earth's magnetic field can serve as a magnetic compass. • Orientation is affected by experience, species differences, and amount of stored energy. • Bees, Homing pigeons, am. alligator • Sea turtles: travel tens of thousands of kilometers during their lifetimes - Continuously swimming for weeks; With no land in sight Birth and then off, using local cues to head toward the ocean. When they first enter the ocean, they swim into the waves - To maintain an offshore heading, taking them out to sea - In the open ocean, waves are not a navigational cue - They can come from any direction based on the inclination of the magnetic lines of force. - Similar to a bird's compass - Hatchlings swim toward magnetic northeast in the normal geomagnetic field. - Continue to do so when the field is experimentally reversed

Sea turtle migration

• As a sea turtle matures, it learns the geomagnetic topography of specific areas • This is part of the map it uses to locate an isolated target (i.e. a nesting beach) • After spending years in the North Atlantic gyre • Sea turtles migrate between summer feeding grounds and winter feeding grounds in the south • Adults return to nest on the same beaches where they hatched • The earth's magnetic field provides a map that tells them their position relative to a goal. • Juveniles and adults use the geomagnetic field as navigational map • A more complex use than hatchlings • The magnetic field tells the turtle whether it is north or south of its goal • Simply put, turtles have a GPS system.

Carnivores

• Carnivores must capture food that never benefits from being eaten • Evidence of an arms race: prey species have evolved defenses against predation • Predators have evolved to overcome those defense

Avoid being eaten

• Changes in foraging behavior in the face of predation include •Avoiding dangerous places: Chacma baboons live in four different habitats and each differs in food availability and predation risk • Avoiding dangerous times of day: Scorpions forage less on moonlit nights when they are more visible to predators • Increasing vigilance when foraging: • Vigilance comes with an energetic cost - it is hard to be both vigilant and forage. Greater elk spend more time being vigilant and less time feeding when wolves are present • Selecting portable foods: Foraging gray squirrels reject items with a higher profitability (energy gained per second of handling time) • For larger, less profitable items that easier to carry to cove

Sun Compass

• Determining compass direction from the position of the sun. (problematic if cloudy) • The specific course that the sun takes varies with the latitude of the observer and the season of the year. • But it is predictable • Its use is complicated by its apparent motion through the sky. • The sun appears to move at about 15° an hour. • Species that take short trips do not adjust their course. -What about long distances? -An animal traveling for long periods compensates for the sun's movement. -It measures the passage of time and adjusts its angle with the position of the sun. -After 6 hours of travel, an animal switches from having the sun 45° to its left to a 45° angle, with the sun on its right. -Time is measured by using a biological clock.

Astounding migration

• Different species use different navigational mechanisms • An arctic tern circumnavigates the globe • A monarch butterfly flutters thousands of miles to Mexico • Orientation systems include: multiple cues, a hierarchy of systems, transfer of information among various systems. • A species can use several navigational mechanisms • If one mechanism becomes inoperative, a backup is used • Navigational systems may use multiple sensory systems

Electrical cues and electrolocation

• Electrical cues have many uses for those organisms that can sense them. • What are some? • Foraging: Predators use electrical cues from organisms to detect prey • Navigation: Electrical fields generated by nonliving sources (i.e. ocean currents, waves, tides and rivers) provide cues for navigation • There is no evidence that migrating fish such as salmon, shad, herring, or tuna are electroreceptive • But electrical features of the ocean floor may help guide the movements of bottom-feeding species (i.e. dogfish shark) • Generate pulses, creating electrical fields used in communication and orientation. • Example: electric organs located near the tail of weak electric fish generate brief electrical pulses.

Star compass

• Example: Caged warblers housed in a planetarium oriented themselves in the proper migratory direction for that time of year. • When the star pattern of the sky was rotated, the birds oriented according to the sky's new direction. • When the dome was diffusely lit, the birds were disoriented. • When the moon and planets were not projected, the birds oriented correctly by taking their bearings from the stars. -Stars rotate around the polaris which provides the most stationary reference point in the northern sky • Other constellations rotate around it. • Birds learn that the center of rotation of the stars is in the north which guides their migration northward or southward • It is not necessary for all constellations to be visible at once • Once their star compass has been set, birds do not need to see the constellations rotate. • Simply viewing certain constellations is enough • The star compass has been studied in only a few species. • Garden warblers and pied flycatchers also learn that the center of celestial rotation indicates north.

Foraging

• Foraging: finding, processing, and eating food • Foraging decisions are based on a food item's size • Energetic value • How easy it is to carry • Its distance from cover • And how these variables interact • Animals must consume either plants or other animals to live • Acquiringenergy,carbonandnitrogenbyfeedingonother organisms • Animals have a wide range of adaptations for acquiring food

Orienting with landmarks

• Homing pigeons wearing frosted contact lenses did not see well. • Their flight paths were still oriented toward home. • What does this tell us then? • Pigeons do not need landmarks to guide their journey home. • But they may use landmarks when they are available.

How an animal perceives risk: cascading effect

• How do animals assess how risky they perceive a particular site to be? • When given a choice, gerbils prefer a safe plot over a risky plot (i.e. with owls during a full moon) •When both plots held the same number of seeds • Gerbils accepted increased risk when the price was right •If the risky plot contained enough seeds • Antipredator behavior can have a cascade of consequences for an ecological community •ecological consequences of anti predator behavior by foragers are wide-ranging • To avoid detection, grasshoppers decrease their movements in the presence of spiders •Reducing the amount of plant damage by grasshoppers • The spiders' mere presence changed the behavior of the grasshoppers enough • To have a significant, measurable impact on plant

Electrolocation

• In muddy water or in fish that are active at night. • Distinguishing between living and nonliving objects in the environment. • An object with greater conductivity than that of water (i.e. another animal) directs current toward itself . • Objects that are less conductive (i.e. a rock) deflect the current away. • Distortions in the electrical field create an electrical image of objects. • Telling a fish a great deal about its environment. • Varies according to the location of the object • The location of the image on its skin tells the fish where the object is located. • The fish performs a series of movements close to the object under investigation. • To provide sensory input that helps the fish determine the object's size or shape. • It builds a map.

Visual cues: polarized light

• Many animals orient correctly even when their view of the sky is blocked- use cue in patches of blue sky. • Light consists of many electromagnetic waves vibrating perpendicularly to the direction of propagation. • Unpolarized light: light waves vibrate in all possible planes perpendicular to the direction in which the wave is traveling • In polarized light: all waves vibrate in only one plane (vertical or horizontal) • Sunlight passing through the atmosphere becomes polarized by air molecules and particles • The degree and direction depend on the position of the sun (can tell direction of sun, even through clouds) • Polarized light is used as an axis for orientation. • An animal moves at an angle from the plane of polarization. • And provide orientation cues at dawn and dusk, when the sun is below the horizon. • Many birds that migrate at night set their bearings at sunset when polarized light is a more important orientation cue than the sun's position or the geomagnetic field

Magnetic cues

• Organisms can orient relative to the earth's magnetic field. • For direction finding and long and short distance navigation. • Advantages to using the earth's magnetic field as a compass? 1. Used where visual cues are limited or absent. 2. Unlike celestial cues, it is constant year round, night and day. • The magnetic poles are shifted slightly from the geographic, or rotational, poles. • The earth's magnetic declination: the difference between the magnetic pole and the geographic pole • Small in most places (< than 20°) • Magnetic north is usually a good indicator of geographic north.

Compass orientation: path integration

• Path integration: the animal integrates information on the sequence of direction and distance traveled during each leg of the outward journey. • Then, knowing its location relative to home, the animal can head directly there, using its compass. • It knows the shortest route.

Herbivory

• Plants - roots, leaves, stems, fruits, flowers - are consumed by different species of animals • The plant's perspective: it suffers a loss of fitness if an animal eats its roots or leaves • But benefits if its pollen is transferred to another plant • Or if its seeds are carried to a new germination site • Challenges facing an herbivore depend on whether the plant is marshalling a defense that must be overcome -spikes (cactus), poison/toxic (milkweek sap) • or encouraging animal's attention -fruit and flowers (red or black) with colors which attract frugivoros -birds prefer black and red -flowers have visual cues to attract animals to spread pollen

Electric fish can measure distance

• Regardless of the object's size, shape, or composition • The size (width) of an electrical image increases with distance • Amplitude differences in an electrical image become smaller with increasing distance of the object -Fish use size and amplitude to determine the distance of an object

Salmon migration

• Researchers buried salmon embryos at the bottom of a pond • The embryos emerged and migrated to the sea • And then migrated back to the creek • The marked salmon returned to the site of their incubation • The pond • Navigation in the open seas depends on several sensory cues • Magnetism, sun compass, polarized light, and odors • The olfactory hypothesis of salmon homing: young salmon learn the odors of the home stream • The odor is a mixture of amino acids in the water • Salmon use olfactory cues to locate the mouth of the river in which they hatched • Following a chemical trail to the tributary where they hatched • If they choose the wrong branch, they return to the fork and swim up another branch

Search Image

• Search image: the heightened ability of a predator to detect a target; look for particular features • After an animal gains experience with a particular species of prey it begins to focus its attention on it, and ignores other prey that did not fit the search image • This overselection is exhibited when prey are camouflaged or hard to find • Obvious prey are eaten • This hypothesis assumes that a search image is specific • Animals improve in their ability to detect a particular kind of prey • Through experience, an animal learns a prey's key characteristics • The predator looks for others of that type

Different approach to herbivory

• Some species cultivate some or all of their food • Agriculture has evolved independently in three insect orders: ants, termites, ambrosia beetles • Leaf cutter ants cut fresh leaves and carry the pieces back to the nest under the ground • The fungus that grows on the leaves is the ants' primary food source • Limpets (related to snails) leave behind mucous trails. Mucous traps microalgae and stimulates its growth • Limpets revisit their old slime trails to harvest the crop • Gorillas rip down large plants resulting in a surge in the growth young, fast-growing vegetation

Chemical cues

• Some species use olfactory cues for orientation during homing. • Example: Olfaction and salmon homing • Salmon hatch in the cold, clear fresh water of rivers or lakes and then swim to sea • After several years, they reach their breeding condition and return to the very river from which they came • Swimming upstream, they return to the specific location of the natal stream in which they were born

True Navigation

• The ability to maintain or establish reference to a goal, regardless of its location, without use of landmarks. • The animal cannot directly sense its goal • If displaced while en route, it changes direction to head again toward its goal • Only a few species have true navigational ability. • Homing pigeons • Oceanic seabirds • Sea turtles

Light dependent magnetoreception in birds

• The magnetoreceptor is located in the right eye. • Birds cannot remain oriented to a magnetic field in darkness. • Light must of specific wavelengths • Blue light is needed to remain oriented to a magnetic field • Birds may orient to red light if they are given time to adjust • Cryptochrome: a photopigment involved in magnetoreception • Stimulates photoreceptors differently depending on the orientation of the magnetic field • Migratory birds sense the magnetic field as a visual pattern

Magnetoreception in birds

• The two mechanisms of magnetoreception serve different functions • The light-dependent mechanism: a magnetic compass • The magnetite based mechanism: detects minute variations in earth's magnetic field and is part of the magnetic "map" receptor • To use the geomagnetic field as a map, an animal compares the local intensity of the field with that at the goal.

Nesting Behavior of the Digger Wasp: Timbergen

• Tinbergen used this experiment to test his prediction that digger wasps use landmarks to keep track of the location of their nests • In the experiment, Tinbergen placed a circle of pinecones around a nest opening • After the female flew away, Tinbergen moved the pinecones a few feet to one side of the nest opening - When the female wasp returned, she flew to the middle of the circle of pinecones rather than to the actual nest opening • Tinbergen next arranged the pinecones in a triangle around the nest and made a circle of small stones off to one side of the nest opening and this time flew to stones • The wasp cued in on the arrangement of the landmarks rather than the landmarks themselves • This experiment demonstrated that the wasp did use landmarks and that she could learn new ones to keep track of her nest

Rule of thumb

• To determine whether it is beneficial to switch foraging locations • Time spent checking other trees is time lost feeding, so there is an optimal amount of sampling • Chipmunks spend more time sampling the food density at other locations as the quality of the patch being exploited decreased • Other animals may or may not have time to accurately sample their area • They assess their environment by watching conspecifics • Animals may get close enough to an optimal behavior by following a approximation called a "rule of thumb" • Northwestern crows search during low tide for whelks • A crow will pick up a whelk (large snail) then drop it • Crows are selective about the size of whelks they drop • Large whelks provide more energy • And require fewer drops to break

Predators can generate electrical fields

• To sense disturbances in the field created by prey • The nocturnal black ghost knifefish uses its electrical sense to feed on insect larvae and crustaceans • Tuberous electroreceptor organs detect changes in the electrical field the fish generates and uses for orientation • Ampullary organs detect electrical fields generated by external sources (i.e. a prey animal) • These receptors, and the mechanosensory lateral line system, help the fish hunt for prey at night or in muddy water • These fish swim backward, upside down or horizontally • Changing position affects the incoming electrical signals

Magnetic signposts

• Triggering changes in swimming direction during the open-sea navigation of sea turtles • Hatchling loggerhead sea turtles first swim toward magnetic northeast using the earth's magnetic field as a compass • Bringing them to the Gulf Stream • Then to the North Atlantic gyre, a circular current that flows clockwise around the Sargasso Sea • Where they remain for 5 to 10 years • Inherited orientation responses to magnetic fields keep the young in the gyre.

Is there a magnetic map?

• True navigation requires not only a compass but also a map. • The map is used to know one's position relative to the goal • A compass guides the journey in a homeward direction • An animal has a magnetic map if it can obtain positional information from the Earth's magnetic field • Relative to a target or goal • The map may be inherited or learned • Specific or general

Effects on development and activity of the central nervous system

∗ Circulating hormones affect behavior by influencing the central nervous system ∗ They influence different regions of the brain, including the (1) volume of brain tissue (2)number of cells in brain tissue (3)size of cell bodies (4)extent of dendritic branching (5)percentage of neurons sensitive to particular hormones (6)survival of neurons

Steroid hormones: not so simple

∗ Genomic steroids: bind to receptors inside the cell ∗Modify gene expression and protein synthesis over hours or days to produce long-lasting effects on behavior ∗ Nongenomic steroids: can produce rapid behavioral responses (seconds or a few minutes) ∗Don't involve modifications to gene expression and protein synthesis ∗ Peripheral steroids: produced by the gonads and adrenal glands of vertebrates ∗ Neurosteroids: produced by the nervous system and don't travel in the bloodstream but through the nervous system

Sex steroids

∗ Hormonal output is not rigidly determined by sex ∗ Females have small amounts of "male hormones" such as testosterone ∗ Males have low levels of "female hormones" including estrogens ∗ Although different hormones produce different effects, the sex steroids are chemically very similar

Effects on sensation and perception

∗ Hormones influence the ability to detect certain stimuli ∗ And the responses to and preferences for particular stimuli ∗ In some species, mate choice is based on hormone- mediated differences in the ability to detect stimuli ∗ ex: Female domestic pigs are attracted to the boar pheromone, 16-androsterone, while males are not -Castrated males given the male hormone estradiol show female responses to a boar ∗ Hormones can mediate behavioral responses to stimuli

How hormones influence behavior

∗ Hormones modify behavior by affecting sensory or perceptual mechanisms ∗ Development or activity of the central nervous system ∗ Muscles important in the execution of behavior

Mechanism of action: peripheral steroids and neurosteroids

∗ Neurosteroid mechanisms of action resemble peripheral steroids ∗Binding to receptors in the target cell and affecting gene expression ∗Others influence receptors on the membranes of neurons ∗ Still others act on microtubules (components of the cytoskeleton involved in cell transport, division and movement) within neurons ∗ Steroid hormones are produced by more locations within the vertebrate body ∗ Have very diverse mechanisms of action

Peptides

∗ Peptide hormones: chains of 3 to 300 amino acids ∗ Water-soluble ∗ Affect cells by binding to receptor molecules on the cell surface ∗ Involve complex molecular interactions, including secondary messengers (i.e. cAMP) ∗ Create short-term changes in cell membrane properties ∗ Activates enzymes ∗ For long-term changes in protein function ∗ Examples: luteinizing hormone (LH) and follicle- stimulating hormone (FSH)

Hormones can cause a change in preference in animals

∗ Sex steroids can change social preferences ∗ Given a choice of social partner, young animals that received parental care prefer family members ∗ As they mature, they prefer non-family members ∗ Hormone-mediated changes in social preference are not limited to maturing animals ∗In winter, adult female meadow voles prefer other females ∗During mating season (spring and summer), they prefer males ∗This reversal in preference is caused by higher estrogen levels, associated with longer days

Steroid hormones are substitutabile

∗ Some hormones lie along the pathway of synthesis of other hormones ∗ Testosterone is an intermediate step in the synthesis of estradiol ∗ Because these two have a similar structure, some behavior patterns may be activated by injections of either testosterone or estradiol ∗ A degree of substitutability is associated with these hormones

Steriods

∗ Steroid hormones: secreted by the gonads and adrenal glands in vertebrates ∗ Major classes: progestins, androgens, estrogens, and corticosteroids ∗ The first three are secreted by the gonads and are called sex steroids ∗ Are chemically derived from cholesterol ∗ Are highly fat-soluble ∗ Move easily into the cell's interior (cytoplasm) ∗ Once inside a cell, steroids combine with receptor molecules ∗ If binding occurs in the cytoplasm ∗ This complex moves to the nucleus ∗ And attaches to DNA ∗ Affecting gene expression and protein synthesis ∗ Takes hours or days and produces long-lasting effects on behavior

Vastocin influences mate choice in males

∗ Vasotocin enhances male responsiveness to female stimuli ∗ Male newts first rely on visual cues (i.e. size, shape, and color) ∗ Then switch to olfactory cues for close-up confirmation of species, gender, and reproductive state ∗ The male clasps the gravid female for hours in amplexus (become rigid) ∗ The female becomes sexually receptive