4/3 ATB What is hibernation? Today: Go over test Describe photoperiod

4/10 ATB What is photoperiod? Today: Begin quick chapter on photoperiod and hibernation.

Photoperiod & Hibernation

Photoperiod Photoperiod (or photoperiodism) – Examples: What makes light so important? Energy source for photosynthesis But also plays an important influencing plant / animal behavior Photoperiod (or photoperiodism) – Duration of an organism's daily exposure to light and… …the effects of the exposure on the organism Examples: Growth Development

4/11 ATB Name at least three examples of how photoperiod can affect organism behavior. Today: Continue discussing lights affects on organisms Turn in article questions Test – next Tuesday? PSSA’s Pd 1 – E218 (Mr. Freeman) Pd 3 – A202

Photoperiod – Affect on Plants What main purpose of light in plants? Photosynthesis What is the graph below stating? As light (irradiance) increases, the rate of photosynthesis increases until saturation point is met Why doesn’t the rate of photosynthesis continue to increase? Because the cellular machinery is saturated or at “full capacity”

Light Tolerances Remember: Shade tolerant vs. shade intolerant Different plants have different tolerances for the length of the photoperiod Look at the graph: Which is the “shade” leaf? How do you know? B. Faster growth with lower light. Saturation point reached sooner

Light – Other influences on Plants Acts as a Timing mechanism Keeps plants in tune with daily and seasonal changes Triggers plant activities Leaves unfolding or falling off Production of flowers and seeds Some bloom in lengthening days of spring to make the most out of the available sunlight Some flower only during days of shortening daylight

Critical daylength - Example: The duration of light (or dark) that it inhibits or promotes a response from the organism Usually falls between 10-14 hours Example: Only in 10 hours of daylight will a plant bloom

Short-day vs. Long-day Plants Short-day Plants – Only bloom when amount of light is LESS than their critical period EX: Only flower when there is LESS than 10 hrs of light Long-day organisms - Only bloom when amount of light is MORE than their critical period EX: Only flower when there is MORE than 10 hrs. of light

Short-day vs. Long-day Plants

It actually may be the length of the DARK period rather than the light that controls the organisms response. The terms long day/short day plants are actually misnomers. Research has proved that when the long night period was interrupted by a brief exposure to light, the plants failed to flower. So the scientists concluded that what is essential for flowering is long and uninterrupted dark period rather than a short day length. A brief interruption of the dark period with light nullified the effect of long night. So short day plants were called long night plants and long day plants were called short night plants.

4/12 ATB What is a critical day length? Today: Circadian rhythms

Day-Neutral Day-neutral organisms – not affected by daylength Examples: Tomatoes, cucumbers, sunflower, dandelions and cotton What could be some signaling factors for these organisms? Rain, temperature or others

How do horticulturists (people who cultivate plants) exploit short-day and long-day responses? Forcing plants to bloom throughout the year using artificial light How you get flowers in middle of winter

Circadian rhythm Circadian rhythm - Biological clock Rhythm of activity and inactivity covering 24 hours characteristic of living things Biological clock Timekeeper of physical / physiological activity in livings things Circadian rhythms are important in determining the sleeping and feeding patterns of all animals, including human beings. Circa = around diem or dies = "day”

Examples: Growth of antlers in male deer (hormonal changes) Reproductive cycle of deer / sheep – shortening days of fall Birds -- breeding season during the longest days

Rhythms of Waking and Sleep What is jet lag? disruption of the circadian rhythms due to crossing time zones. mismatch of the internal circadian clock and external time. Characterized by sleepiness during the day, sleeplessness at night, and impaired concentration. Traveling west “phase-delays” our circadian rhythms. Traveling east “phase-advances” our circadian rhythms.

Figure 9.6: Jet lag. Eastern time is later than western time. People who travel six time zones east fall asleep on the plane and then must awaken when it is morning at their destination but still night back home.

4/13 ATB What is jet lag? Today Finish chapter – hibernation and feeding habits Finish article

Light also affects when species become active in search of food

Nocturnal Nocturnal - Organisms that are adapted to night activity Usually have highly developed sense of smell and/or hearing and/or eyesight Some organisms can function during the day or night (cats) Others are strictly nocturnal (bats, bushbabies) Many have large eyes in order to see in low light conditions

Diurnal Diurnal - Examples: Organisms that are active during the day (sleep at night) Examples: Squirrels, many birds

Crepuscular Crepuscular - Organisms that are active during twilight periods (during dawn and dusk) Crepusculum - meaning "twilight” Evolved as a possible way to avoid predators who may be active during the middle of the day or during the night Examples: Cats, dogs, rabbits, skunks, deer

Torpor Torpor (“temporary hibernation”) – State in animals where body temp. falls, metabolism decrease and O2 intake falls Usually to save energy during cold temps Can be short term or long term Body restores to normal when the animal becomes active Seen as a way to save energy when the animal is not active Will awaken to stimuli Young bats w/o enough stored energy may die

Examples: Lungfish Hummingbirds, mice, bats may use this when their pool dries up Have lungs – can breath air Hummingbirds, mice, bats

Hibernation Hibernation – Body temps drops to (almost) environmental temp (almost freezing) Substantial drop in metabolic rate Lower oxygen intake Animals may wake, but not from stimuli (like predators, making them easy prey if found) What is the goal? survive during periods of cold weather with little food Organisms must eat large amounts of food prior to hibernation Examples: Woodchuck, ground squirrels some rodents

Winter hibernation - Winter's Tale - BBC http://www.youtube.com/watch?v=3hSGuYMOe3E&feature=fvsr Black bear and cubs in hibernation - BBC wildlife http://www.youtube.com/watch?v=TpY4frpheWw http://www.youtube.com/watch?v=3hSGuYMOe3E ‪Waking up from Hibernation - Animals: The Inside Story – BBC‬ http://www.youtube.com/watch?v=Svm6yqKx-Go&feature=relmfu

Do bears hibernate? Most do not consider it a “true” hibernator Body temp. does drop, but not as much as a “true hibernator” Metabolism does decrease Heart rate does decrease Totally rely on large amounts of stored energy in their fat Do not eat, drink, defecate or urinate

The End

4/16 ATB What happens to an organisms body as they enter hibernation? Today: Review for the test Test / Study Guide – Tomorrow Don’t forget PSSA’s Pd. 1 – E218 (Mr. Freeman) Pd. 3 – A202

IV. Abiotic Factors: Light Major concepts in this unit: a. how light is measured b. plant adaptations to light c. circadian rhythms and animals d. biological clocks e. photoperiodism/phenology f. Subunit: Raptors (highlight diurnal/nocturnal adaptations) g. Subunit: Whitetail deer (highlight periodicity in animals)