Lec 7: Rhythms HW2 In-class review and discussion of HW2 Handout “Guidelines for answering short answer questions” Lecture clarification sympatric speciation, character displacement Circadian Rhythms

HW2

In-class review and discussion of HW2

Handout “Guidelines for answering short answer questions”

Lecture clarification sympatric speciation, character displacement

Circadian Rhythms

Animal Behavior, Lec. 6, BIOL 4518 Sympatric speciation Create a species - > How? restrict gene flow Who? Among members of the same population

Create a species - >

How? restrict gene flow

Who? Among members of the same population

Sympatric Speciation Sympatric speciation is a theory Does this happen in nature? Why is it controversial? Is instantaneous or gradual more likely to be a mechanism used?

Sympatric speciation is a theory

Does this happen in nature?

Why is it controversial?

Is instantaneous or gradual more likely to be a mechanism used?

Sympatric speciation Mechanisms for restricting gene flow in a population Polyploidy How does this work? Is behavioral isolation involved?

Mechanisms for restricting gene flow in a population

Polyploidy

How does this work?

Is behavioral isolation involved?

Reproductive character displacement 2 Components Female discrimination females are choosy! Females choose among variation in male traits “Receiver preference function” Male character divergence Over time key traits in males become more and more different Bimodal distribution

2 Components

Female discrimination

females are choosy!

Females choose among variation in male traits

“Receiver preference function”

Male character divergence

Over time key traits in males become more and more different

Bimodal distribution

Reproductive character displacement How would it work? What is reinforcement? Is low hybrid fitness required? How do hybrid offspring have low fitness?

How would it work?

What is reinforcement?

Is low hybrid fitness required?

How do hybrid offspring have low fitness?

Reproductive character displacement Evidence supporting this theory Polyploid frogs Character: Female discrimination: Cause of low hybrid fitness:

Evidence supporting this theory

Polyploid frogs

Character:

Female discrimination:

Cause of low hybrid fitness:

Reproductive character displacement Evidence supporting this theory Polyploid frogs Character: vocalization Value which females discriminate: frequency of pulses Cause of low hybrid fitness: 3N are not viable Song bird

Evidence supporting this theory

Polyploid frogs

Character: vocalization

Value which females discriminate: frequency of pulses

Cause of low hybrid fitness: 3N are not viable

Song bird

Summary Reproductive Character Displacement and Sympatric Speciation Sympatric restrict gene flow within a pop. Low hybrid fitness Mechanisms Instantaneous: Polyploidy Gradual: Female discrimination and male character divergence Why controversial?

Sympatric

restrict gene flow within a pop.

Low hybrid fitness

Mechanisms

Instantaneous: Polyploidy

Gradual: Female discrimination and male character divergence

Why controversial?

Geomagnetism: Earth's Magnetic Field Gary A. Glatzmaier

Geomagnetism: Earth's Magnetic Field Gary A. Glatzmaier Why does the Earth have a magnetic field How is it generated? Poorly understood Hypothesis: Iron-rich magma in the earth's crust rises with heat and sinks with cooling generating the field

Why does the Earth have a magnetic field

How is it generated?

Poorly understood

Hypothesis:

Iron-rich magma in the earth's crust rises with heat and sinks with cooling generating the field

Geomagnetism: Earth's Geomagnetism: Earth's Magnetic Field: Animal navigation Is it changing? Yes! Polarity changes North and South magnetic poles reverse Evidence in tectonic plates on sea floor that preserve the polarity as the new magma cools Field strengthens and weakens the dipole moment will decay in about 1,300 years. How often does the magnetic field reverse? During the past 100 million years, the reversal rates vary (5 thousand years to 50 million years). Last reversed 750,000 - 780,000 years ago.

Is it changing?

Yes!

Polarity changes

North and South magnetic poles reverse

Evidence in tectonic plates on sea floor that preserve the polarity as the new magma cools

Field strengthens and weakens

the dipole moment will decay in about 1,300 years.

How often does the magnetic field reverse?

During the past 100 million years, the reversal rates vary (5 thousand years to 50 million years).

Last reversed 750,000 - 780,000 years ago.

Geomagnetism: Pigeon navigation Pigeons navigate in overcast skies Suggest they are using magnetic field

Pigeons navigate in overcast skies

Suggest they are using magnetic field

Geomagnetism: Pigeon navigation Pigeons navigate in overcast skies Suggest they are using magnetic field Evidence?

Pigeons navigate in overcast skies

Suggest they are using magnetic field

Evidence?

Geomagnetism: Pigeon navigation Pigeons navigate in overcast skies Suggest they are using magnetic field

Pigeons navigate in overcast skies

Suggest they are using magnetic field

Geomagnetism: Pigeon navigation Pigeons navigate in overcast skies Suggest they are using magnetic field

Pigeons navigate in overcast skies

Suggest they are using magnetic field

Electromagnetic Fields: Animals In addition to the use of the geomagnetic field for navigation, Some animals generate their own electric field for example for prey detection

In addition to the use of the geomagnetic field for navigation,

Some animals generate their own electric field for example for prey detection

Summary Geomagnetism, Electromagnetic fields Geomagnetism Electromagnetic fields generated by animals

Geomagnetism

Electromagnetic fields generated by animals

Time – circadian rhythm Clock is affected by environmental cues Clock is not affected by environmental cues Evidence: Conclusion – somewhere in the middle; free-running cycle updated with some environmental cues

Clock is affected by environmental cues

Clock is not affected by environmental cues

Evidence:

Conclusion – somewhere in the middle; free-running cycle updated with some environmental cues

Organization of clocks and behavior Chemical clock Clock located in central place Receives input and adjusts Sends signals to other behaviors

Chemical clock

Clock located in central place

Receives input and adjusts

Sends signals to other behaviors

Organization of clocks and behavior Chemical clock per PER, tau CKl e Clock located in central place Hypothalamus Suprachiasmic nucleus (SCN) Receives input and adjusts e.g., light on retina Sends signals to other behaviors PK2

Chemical clock

per PER, tau CKl e

Clock located in central place

Hypothalamus

Suprachiasmic nucleus (SCN)

Receives input and adjusts

e.g., light on retina

Sends signals to other behaviors

PK2

How is a clock made Endogenous Pacemaker, master clock Free-running cycle Gene product feedback

Endogenous

Pacemaker, master clock

Free-running cycle

Gene product feedback

How is a clock made

Cycles/Rhythms Single cycles Daily Lunar Tidal Seasonal Annual Multiple years Combinations of cycles

Single cycles

Daily

Lunar

Tidal

Seasonal

Annual

Multiple years

Combinations of cycles

Cycles/Rhythms

Circadian cycles Absence of cues Human sleep patterns

Absence of cues

Human sleep patterns

Lunar Cycles Lunar cycles

Lunar cycles

Lunar cycles - cues Hydrostatic pressure Temperature Salinity Turbulence Vibrations Immersion

Hydrostatic pressure

Temperature

Salinity

Turbulence

Vibrations

Immersion

Lunar Cycles - tides

Tidal cycles Intertidal pools of various heights Protists Encysted (18hr) and free swimming (6hr) Cycle – remain in pools during flooding Encyst for 2 high tides and one low tide Faster rhythms and change in phase and duration on lower tide pools

Intertidal pools of various heights

Protists

Encysted (18hr) and free swimming (6hr)

Cycle – remain in pools during flooding

Encyst for 2 high tides and one low tide

Faster rhythms and change in phase and duration on lower tide pools

Which cycle is the cue? Intertidal brown shrimp live in pools created at high tide They are exposed to both diurnal and tidal cycles What are cue are they using?

Intertidal brown shrimp live in pools created at high tide

They are exposed to both diurnal and tidal cycles

What are cue are they using?

Which cycle is the cue?

Which cycle is the cue?

Which cycle is the cue?

Which cycle is the cue?

Seasonal Cycles Hibernation without external cues

Hibernation without external cues

Multiple Years Cicadas Only in North America Spend most of life in ground in larval stages Emerge every 13 or 17 years Co-occur every 221 years! Emerge within a few days of each other Several species identified

Cicadas

Only in North America

Spend most of life in ground in larval stages

Emerge every 13 or 17 years

Co-occur every 221 years!

Emerge within a few days of each other

Several species identified

Multiple Years Can sympatric speciation occur by temporal displacement? Why would this be controversial, given what we have been discussing? What would you expect to observe if sympatric speciation occurred?

Can sympatric speciation occur by temporal displacement?

Why would this be controversial, given what we have been discussing?

What would you expect to observe if sympatric speciation occurred?

Multiple Years

Multiple Years Character divergence

Character divergence

Multiple Years

Multiple Years Suggests single gene change speciation event

Suggests single gene change speciation event

Summary on cicadas Sympatric speciation through timing? Character divergence

Sympatric speciation through timing?

Character divergence

Combinations of cycles Ocean Tidal cycles

Ocean

Tidal cycles

Relative vs. absolute time

Clock shifts Clock shifted pigeons change

Clock shifted pigeons change