Bio Two, Exam 4 Info

Endotherms vs. ectotherms and how they are adapted to maintain homeostasis in different ways?

Ectotherm: Gains heat from external sources (relies on environment to control its temperature)

• “Cold-blooded”

• Ex: basking in the sun, seal

Endotherm: Gains heat from metabolism

• “Warm-blooded”

• Ex: birds

Feedback loops involved in thermoregulation?

The hypothalamus acts as a thermostat

• Major regulating system of the body

• *regulate internal temperature

Negative feedback

Ex: exercise

Body temperature goes up

Hypothalamus acts on different tissues/glands

• Blood vessels dialate, brings the blood closer in contact with the surface

• Sweat, evaporative cooling

*Body temperature goes back down again

Positive feedback

Ex: rapid temperature drop

Body temperature goes down

Hypothalamus acts on muscles/tissues/glands (like before)

• Constrict blood vessels

• Shiver

• Shunt blood to core

*Body temperature goes back up again

Simple vs neuroendocrine pathways and examples?

Neuroendocrine pathways involve sensory nerves 

• (nerves and hormones)

Ex: suckling

Mammal suckling feedback loop

1. Stretching of mechanoreceptors in breast tissue

2. Impulses reach the hypothalamus

3. The hypothalamus sends signals to the posterior pituitary gland

4. Posterior Pituitary releases oxytocin

   1. If the hormones are released, animals do not want to have another mate

5. Oxytocin triggered milk release from the breast tissue

^positive feedback, the more milk, the more the suckling is encouraged

Simple endrocrine responses do not involve the nervous system

I.e.: Secretin produced by S cells

^negative feedback, the more food, the urge to eat more will stop

Feedback loops involved in the process of digestion?

Stomach distension releases gastrin (triggers HCl release) HCl digests food

• When sthe tomach stretches, gastrin is released

HCl degrades proteins

HCl activates pepsin a (protease, an enzyme that breaks down proteins, fully in the stomach)

• Normally, in inactive form called pepsinogen, HCl activates it to become pepsin

Acidic, partially-digested food (chyme) causes the release of secretin and CCK (triggers digestive enzymes from the pancreas)

• Digestive enzymes like Trypsin (breaks down proteins in the small intestine)

• Once released, it slows further digestion, preventing gastrin release (“fullness”)

What distinguishes male and female animals/how this influences behavior?

Males produce smaller gametes

Females produce larger gametes

• Invest more in reproduction

Males rush to females

Male cardinal will feed the female because the female does so much and it benefits him because offspring would survive

Sex determination in animals (including birds and mammals)?

In some species, individuals produce sex organs. hermaphrodites

• Earth worm

Sex can be determined by temperature

• Common in reptiles

Come switch sexes

• Hagfish, often 1 male to 100 females

• If a male dies, the ratio is not good for the population, so females can switch

Role of the y chromosome in mammalian sex determination?

Mammals: Y chromosome converts indifferent gonads to male

• The default is female unless a Y chromosome is present, SRY gene

• Males determine the sex of the offspring

Internal vs. external fertilization?

External fertilization

Female fish and amphibians shed eggs that are fertilized by males

• Fusion happens outside of the body

• Common in amphibians, frogs, and ray-finned fish

ADVANTAGE: Very cost-effective, not actually allowing the fertilized offspring to develop in the body for a certain amount of time. No time inside of her.

• Offspring develop outside of the female

• As easy as it gets

DISADVANTAGE: Because the offspring are open without the mother, they will likely die from predators. 

• “Infant” mortality is high.

• Most likely will get eaten

*IDEAL when offspring mortality is likely

Internal fertilization

In mammals, birds, and reptiles, males deposit sperm in female

A female will harbor the offspring at least for a certain amount of time

• Most investment by females

ADVANTAGE: lower offspring mortality rate

DISADVANTAGE: fewer offspring

*IDEAL when offspring mortality is low

Semelparity vs. iteroparity as reproductive strategies?

Iteroparity: continuous reproduces, animals that can reproduce multiple times in their life

• Humans

• Continued offspring production

Semelparity: can only reproduce one time in its lifetime

Advantages of semelparity and examples?

• Dandelion

• Salon swims upstream to fertilize, and the journey kills the salmon. The female hopes a male will come and reproduce

• BENEFITS: 

  • Explosive reproductive output, inversts a lot of energy into this reproductive event (dandalion and salmon)

  • Investing more eggs give the possibility of more fertilization

  • Reduces competition between parents and offspring (some animals cannot tell the difference between offspring and food), salmon sometimes eat their own offspring

  • Offspring feed on other things so there is not competition with the parents

*Reducing sperm competition (common in sexual cannibalism) (praying mantis)

r/K selected traits as a reproductive trade-off?

Trade-off: should animals produce many small offspring or few large?

R-selected species: selection of traits that are ideal in uncrowded environments

• Small

• High mortality rate

• Reproduce in large numbers

• Ex: rodents, because mice are so small their enviroment is big to them

K-selected species: selection of traits ideal in crowded environments

• Large

• Low mortality rate

• Reproduce in small numbers

• Ex: elephant

Reproductive behavior and ecological significance of Brown-headed cowbirds?

Ex: brow-headed cowbird

Scarlet tanager:

Typical host life history:

• 1 clutch of eggs per year

• 3-5 eggs per year

• Takes a lot of time and energy so most of the offspring survive

Cowbird life history: 

• Wait for another bird to lay their eggs

• Wait for the mother to leave then lays an egg in the nest of the other bird

• Incubates the cowbird

• No investment

• May reduce the reproductive success of the host because when the mom comes and sees the cowbird is bigger, she will give it the food. The cowbird will like their behavior and kill off the other birds in the eggs by stabbing of pushing the eggs from the nest.

*Thrive in edge habitat (next to grassland because food is in the grassland)

• Humans fragment forests to build houses, and this benefits them because it creates more edge

• Are native species

• Can not be isolated because they do not know how to reproduce anymore

• Many times the host ends up only raising the other chick

• All efforts go to the cowbird that did no work

• Then cowbird finds another nest to do the same thing and can lay up to 40 eggs per season

• GET THE BEST OF BOTH WORLDS

Human influence on distributions (examples)?

Populations

Dingos would eat live stock

Humans build a fence to prevent dingos from coming in

Vegetation levels drop because the herbivores grew out of control because they were not taken out

Humans have control over where an animals population lives (distribution)

An organism’s distribution is where it is found (also known as range)

*Can be native or introduced

Native naturally found

Introduced ranged where humans have brought it

• Become invasive species outcompeting other animals

• Ex: whitenose fungus., european starling

• Shakespeare enthusiasts brought them to new york and spread

Sometimes species are introduced by nature

• Ex: lemurs, floated on vegetation raft

*Dispersal can affect distribution

Dispersal: a long-distance movement with no return trip

Dispersal during the Great American Interchange and its consequences?

The Great American Interchange

Mammals dispersed between North and South America

North America

• Mostly Placental Mammal

• Result: easily dispersed into South America

• Had a bigger area to live in and create competition, more space to evolve so they were better able to survive

• *Placentals have/had more efficient metabolism and larger brains

South America

• Mostly Marsupials (kangaroos)

• Result: could not disperse into North America

• Possome is the only marsupials that survived

  • Have a lower body temperature and cannot carry rabies

Biotic and abiotic factors that affect/limit growth in specific populations?

Biotic: dealing with living things

• Factors:

• Ex: nesting materials

• Food

• suitable mates

• habitate

Abiotic: dealing with non-living things

• Factors:

• Sunlight

• Salinity (sharks require a certain solute concentration)

• Humidity

• Temperature

Can determine if an organism can live in a certain spot

Africanized bees as an example of exponential growth?

Ex: Africanized Bees: are European honey bees x African honey bees (cross breed)

European Bees

• Docile (not aggressive)

• Form large colonies

• Stationary

African Bees

• Agressive

• String frequently

• Swarm frequently (colony breaks into new colony)

• Honey badger is a big predator

• *Ended up having drones (males) escape and mated with European queens

African traits became more dominant

Symbols used to describe species interactions?

Symbols for species interactions

• Mutualism (+/+)

• Commensalism (+/0)

• Parasitiam/predator (+/-)

• *Competition (-/-)

Examples of animal competition in modern animals?

Competitive exclusion as a consequence of competition?

Resource partitioning as a consequence of competition?

How character displacement occurs in different populations?

Steller’s Jay is the California version of Ohio’s blue jay

Western equivalent of our blue jay

All the unique stuff is the same

Maps shown where they are show they probably never interact

Examples of dominant, keystone, and foundation species (including why they are considered as such)?

Dominant species are the most abundant in a community

• Ex: grasses

• Ex: Kudzu, growing out of control, covering everything. Is becoming a dominant species that should not be a dominant species. Has the ability to grow roots from any part of the body (leaves, stems, and flowers) Lack of things that can keep it in control. Nothing is eating it and grows a lot.

Keystone species maintain diversity within a community

• Ex: bats, they consume so many insects that without them, the amount of insects would grow out of control and destroy other species.

• Ex: coral reef, so many aquatic animals use coral reefs as their habitat

*At least one that we want to see disappear

Foundation species can dramatically alter the landscape of an ecosystem

• Ex: arctic fox. Fur traders wanted to introduce them to different environments, they ended up eating the guano which was responsible for producing a lot of food to fertilize the soil and that caused less vegetation. (humans bring it)

• Ex: American beavers (naturally there). Beavers like the living forests where there are rivers and streams. During winter time there are few places to hide so they decided to build a lodge (structure of circle wood) because they cannot climb trees. In order to go under the lodge they need a slow stream so they build a dam to stop the flow of water making a high pool that few animals can go into it. Create a swampy wetland habitat around them.

• Mature forest -> wetlands

• Same animals benefit (llike more aquatic areas to eat aquatic animals) rail birds, others do not benefit (ots of tall trees so they can nest, beaters tear down the tree) chickadee

Effects of American beavers on landscapes?

Ex: American beavers (naturally there). Beavers like the living forests where there are rivers and streams. During winter time there are few places to hide so they decided to build a lodge (structure of circle wood) because they cannot climb trees. In order to go under the lodge they need a slow stream so they build a dam to stop the flow of water making a high pool that few animals can go into it. Create a swampy wetland habitat around them.

• Mature forest -> wetlands

Same animals benefit (llike more aquatic areas to eat aquatic animals) rail birds, others do not benefit (ots of tall trees so they can nest, beaters tear down the tree) cheacadee

House sparrows as dominant species?

Build nests everywhere

In human cavities (signs)

In other trees, they will kill the birds or eat the eggs so that they can have it to nest themselves

Reproduce multiple times a year

Dominant species

House sparrows became the dominant species because they are aggressive and benefit from human establishments