Animal Behav. Ch. 3: Hormones and Neurobiology

House Sparrow’s in Kenya and its relation to stress hormones

House sparrows were introduced into Kenya and their stress responses increased (corticosterone) as their distance from their original introduction site increased.

• the farther they were from home, the more stressed

Ultimate Perspective Questions

asking a research question in the ultimate perspective is asking the “why.”

• why a certain behaviours evolved in terms of survival and fitness

Proximate perspective questions

• the biological processes that occur that elicit the behaviour 

• ex. hormones, psychological factors, etc. 

House Finch Plumage Example 

• male plumage is brighter than female plumage

• males who were artificially brightened were more likely to mate

• females preferred this because they were eating carotenoid rich foods which made it easier for them to fight off disease

  • less disease passed to offspring

House Finch Plumage experiment

• males were artificially brightened

• artificially brightened males more likely to mate 

• more likely to produce sons with bright plumage 

• more likely to feed their young rather than abandon

  • without bright plumage, they need to work harder for a mate so they abandon their young to mate as much as possible

Endocrine System

system of ductless glands that secrete hormones into the bloodstream of vertebrates

• serves for growth, reproduction, aggression, parental care, metabolism, and other functions 

Difference between protein and steroid hormones

• steroid hormones cannot be stored in cells

  • once they are produced they are released into the bloodstream

• protein hormones can be stored in the cell

HPA axis

Hypothalamic pituitary adrenal 

• a type of activation that stimulates the secretion of hormones in glands

Magellanic Penguin Study

• studied the ethical implications of eco tourism

• penguins exposed to tourists have habituated to being around them and have had reduced defensive responses toward humans than their own species

• however they showed higher levels of stress hormones

Fight or Flight Pathways

• when an individual senses a stressor, the hypothalamus initiates a response which works along one of these 2 pathways

First pathway

• epinephrine is screted by the adrenal gland and nerves in the CNS. 

• burst of this hormone (aka adrenaline rush) and will cause the individual to respond appropriately 

Second Pathway

• three hormones released (CRH, GHRH, TRH)

• these hormones convert non-carbs into sugars which create energy to respond to the situation

In Utero Position Effects in Gerbils

• males surrounded by 2 females in the womb will act feminized and females surrounded by 2 males will act masculine

In Utero Position and Parental Behaviour in Gerbils

• males surrounded by 2 males provided less parental care (which is seen as a masculine trait) 

• males surrounded by 2 females provide more parental care

What do In-Utero Gerbil experiments suggest

that if the fetus is exposed to more testosterone, they will act more mascule and if they are not, they will act more feminine 

Prairie Vole vs. Meadow Vole

• prairie voles have more vasopressin receptors than meadow voles

• this is responsible for their difference in male social behaviour

• prairie voles are monogamous '

• meadow voles are polygamous

Vassopressin and Oxytocin

• hormones produced in the hypothamus and transported to various brain regions or sent to pituitary gland to be released

What role does vasopressin play in parental care in the prairie vs meadow vole?

• when vasopressin was injected into prarie voles, their parental care increased 

• when injected into meadow voles, it did not increase unless their receptors were increased

• shows that vasopressin has a role in parental care behaviours 

Honeybee Foraging

• young bees are usually the nurturers who clean, produce wax, guard the hive

• old bees are usually foragers

• removing the gland that produced the juvenile hormone (JH) in bees resulted in increased foraging behaviour even though it wasn’t their role 

Plainfin Midshipman Fish type 1 and 2

• 2 types of fish 

• type 1: larger, built more nests, produced hums to court females 

• type 2: small, low levels of cortisol, increased sounds during mating season

Midshipman fish experiment

• hypothesized higher levels of different hormones in type 1 and 2 during mating season

• type 1 males had higher KT levels while type 2 had higher cortisol levels

Mushroom bodies and bee foraging

• foraging navigation in invertebrates is known as the mushroom body (cluster of neurons)

• mushroom bodies of foragers were 14.8% larger than other groups

Mushroom bodies experiment

• gathered one day old bees and formed a colony

• their mushroom body configuration was the same as older foragers

• CONCLUSION: foraging related activities trigger a series of neural based changes that make the mushroom body bigger

  • suggests neural plasticity

Brain size and problem solving

theory: larger brains = better at solving novel problems 

Sleep and predation in Mallards — case study brain size and problem solving

Mallards sleep using USWS (one hemiphere is awake while the other eye is open) 

• mallards at the edge of groups keep an eye open

• mallards engage in a tradeoff between rest and vigilance to ensure survival throughout the night 

shows that they are able to solve complex problems 

Whooping Crane Case Study

• shows learned behaviours

• whooping crane video showed them being fed by a fake whooping crane

  • this is because chicks imprint their behaviour on the caregiver

  • if they are raised by a human, they do not reproduce with their own kind

Fruit Fly Interview Tim Tully

flies have similar memory genes to humans called creb genes

• experiment where the fly was shocked with chemicals

• if the fly avoided the scent of the chemical, they remembered the association

• the more creb gene a fly had the easier they remembered the association

Blind experiment

• participants do not know if they are apart of control or experimental group but the researcher does know

Double blind experiment

the researcher nor the participant know the role of the participants in the experiment 

which method is preferred and why?

double blind is preferred to avoid bias because there is a strong placebo affect in humans