How Animals Tell Time (43-46)

How does detecting the passage of time benefit animals?

IT allows them to know when and where they should eat or sleep and when its the best time to reproduce

How do people witness aniamls ability to tell time?

When their pets predictably begin begging shortly before their feeding time every day

Animals sensory organs detect what which allows for telling of time?

Changes in temperatures, pressure, and light

In addition to sensory organs what else allows animals to track time?

Internal biological clock also known as a biological rhythm

What is the process which allows animals to tell time?

Biological rhythm

What did experiments which placed animals in complete darkness without external cues find?

That internal mechanisms regulating daily behavior cycles follow a roughly 24 hour period

_________ rhythms are found in every animal and meet specific ____________ requirements

Circadian; Universal

How often do circadian rhythms repeat?

Once every 24 hours

Circadian rhythms exist even in the lack of what?

External cues like light

Circadian rhythms adjust to what? What do they not adjust to?

They adjust to Local time but they maintain the same rhythm across temperatures

How do other biological rhythms differ from circadian rhythms?

They vary more depending on where the animal is and can range in frequency from seconds to decades

Biological rhythms vary across what durations?

Seconds to decades

How do birds and small mammals predict optimal times for breeding and raising young?

Temperature and length of daylight

What do chickens need to produce eggs>?

Exposure to a certain amount of sunlight

How do many aquatic animals coordinate behavior?>

Lunar cycles which dictate the phases of the tides

Biological cycles regulate what types of behaviors?

Cyclical behaviors which maintain animal life

What is chronobiology?

The study of biological rhythms

When did scientists begins studying how animals can determine when to sleep and wake?

1950s

What organism was used as a model for studying biological rhythms?

The fruit fly

What is the scientific name for the fruit fly?

Drosophila

Why are fruit flies good animals for laboratory conditions?

They are prolific breeders and have a short lifespan so they are easy to breed in short amt of time

What dose the ability to breed multiple generations of an animal allow?

Natural mutatiosn which allows behavior comparisons

What types of fruit flies did scientists select for biological clock experiments?

Those that expressed unusual behavior of sleeping longer or less than others

What hypothesis was created regarding differences in the amount of time fruitflies spent asleep?

Genetic differences

Comparing unusual fruit flies with normal biological rhythms what was found??

That several specific genes regulate the passaGE OF TIME

How are mammals similar to fruit flies in terms of rhythms?

Animals also have similar genes that control their circadian rhytm

What are circadian rhythm genes in fruit flies called?

Period (per)

What are circadian clock genes called in Neurospora crassa?

Frequency (frq)

What is the group of genes that regulates circadian rhythms called in mammals?

Clock genes

Why are period and frequency genes called per and frq?

They produce per and frq proteins respectively

How are all biological clocks across all species similar to animals?

They work vvirtually the same way across all species

How does the biological clock work?

Buildup of a protein as day goes on, then the cell uses feedback to determine the protein has reached upper limit or if it should be produced more. Once its reached capacity cell halts production, eventually it retriggers protein again when levels become too low. This cycle occurs every 24 hours

How many cells in the body maintain the daily biological rhythm?

Every cell

For animals __________ complex rhythms need to be maintained

More

All animals feature a central brain region or neuron cluster which does what?

Coordinates sensory information, circadian rhythm and all tissue in the body

What part of the brain do vertebrate animals which acts as master timekeeper?

Suprachiasmatic nucleus (SCN)

Where is the suprachiasmatic nucleus located?

Deep in the midbrain

What does the midbrain contain?

The most basic functions needed to survive common to all vertebrates

What part of the brain in animals determines complex time passages?

Suprachiasmatic nucleus (SCN)

What system does the suprachiasmatic use to synchronize its rhythm?

The visual system

How is the visual system used by the SCN?

To synchronize its rhythms and determine the start and end of days

What do underground animals rely on for biological rhythm resets?

Cues like temperature or light detecting cells

What is a zeitgeber?

An external cue which allows an animal to detect and regulate its biological rhythm

Zeitgeber is of what language?

German

What does Zeitgeber directly translate to?

Time giver

Zeitgebers allow animals to do what?

Reset or train their biological clock to match the current environment

What do animals which are awake during the day use as a zeitgeber?

Daylight

What do daytime animals do when no light or outside cue can act as a zeitgeber?

Their circadian rhythm follow an approximated 24 hour cycle

When humans experience jet lag what occurs?

The environmental cues and internal clock become mismatched and require a zeitgeber

What is one of the main treatments for jetlag?

Exposing yourself to daylight of current time zone and delay sleeping in til dark

Is jetlag solely human?

No it can occur in animals which travel long distances too, like migraters

The ability of the suprachiasmatic nucleus to do what allows animals to adapt to different environments?

Adapt and act as a master control as environmental cues change

Animals which are exposed to what external cue often engage in behaviors which fluctuate over 24 hours?

light

What is the most observed biological rhythm>?

Sleep-wake cycle

What rhythm determines when animas sleep and wake?

Circadian rhythm

What occurs when the optimal time for an animal to be active arrives?

Hormones and the brain interact in response to signals from the SCN to stay awake or sleep

Activity patterns are broken into what 3 patterns?>

Diurnal, nocturnal, and crepscular

What is diurnal?

Where animals are awake in the day and sleep at night

What is nocturnal?

When animals are awake at night and asleep during the day

What is crepuscular?

When animals are awake at dawn and dusk

What is the nature of the 3 types of activity patterns in terms of their ability to changee?

they can adapt but remain largely fixed

How do migratory birds exemplify shifting activity patterns?

When migrating they fly at night and feed during the day, but when they arrive at their destination they follow normal sleep-wake cycle, adjusting to the new day/night cycle in new environment

How do animals take advantage of weather when migrating?

They travel in cooler weather and lighter wind,

How do migratory birds rest while migrating??

They rest half their brain at a time

Daily rhythms are especially important for which 2 groups of species?

Social and sexual species

Why are biological rhythms important for social/sexual species?

They ended to find others of their species for such behavior and breeding, so if the SCN is damaged or mutated then it can affect fitness

What can cause extreme variations in circadian rhythms which cant be corrected by external cues?

Damage to SCN or a mutation to clock genes

What can extreme variations in SCN cause?

Reduced fitness, and activity when the animal lacks food or perceives an increase in predation risk

Do all animals follow a daily rhythm?>

No

What animal group are examples of some which don't experience daily rhythms? Why?

Animals what live deep underwater, in caves, or near the poles; They experience prolonged periods of darkness so don't follow 24 hour rhythm

What are 2 cues which animals which don't follow daily rhythms adapted to?

Fluctuations in food availability, which helps determine when they need to sleep or forage and changed rhythms based on role in a community

How do honeybees follow different daily rhythms?

Depending on their role in the hive. Workers that forage for food retain a daily rhythm while nurses that stay in the hive stay attentive continuously and rest only when tired

Seasonal rhythms are especially important for what animals?

Those in climates that have dramatic differences in the environment depending on time of year

What do seasonal rhythms allow animals to do?

Use endogenous and exogenous cues to make predictions about how to behave

What cues can signal taht winteris coming?

Diminishing daylight and a consistent temperature drop

What must birds do in response to winter cues?

Choose the best time to migrate to warmer environment

What happens if birds which migrate to warmer areas during winter migrate too early?

They could end up somewhere that doesnt have enough food yet

What happens if migratory birds migrate toa warmer region during winter too late?

They could get stuck in storms and have difficulties migrating

Animals __________ prepare for __________ changes throughout the year

Body; seasonal

What do animals tat hibernate do throughout the year?

SStore excess fat and energy to maintain homeostasis during freezing temps

What is the amount of food that hibernating animals eat and conserve dependent on?

Innate abilities and also partially learned from experience