Topic 2 Migration Flashcards
What are some of the differences that could be seen between migratory patterns?
- Seasonal or not seasonal
- Round trip carried out by an individual or over multiple generations
- Direct of with stop-offs
- Destination used for hibernation, birthing, or both
- A learnt journey or lead by other signals
What is Telemetry?
A process in which individuals are tagged with satellite transmitters that encode position data on a radio sinal to collect data remotely. Often used in migration studies.
Define the term ‘Migration’
The movement from one habitat to another.
What physical property affects how an organism moves and the amount of energy they must exert?
The physical properties of the fluid they are moving through (e.g., water, air)
What does the viscosity of water cause when an organism is moving through it?
Drag
What are the two types of drag that occur when moving in water?
- Pressure drag (frontal area of organism)
- Skin friction drag (surface area of organism)
What is the most influencial force that contributes to the energetic costs of an animal when using air locomotion?
Gravity
What three things would need to be known about a bird to calculate it’s energy cost for air locomotion?
- Force produced by flight muscles
- How much each muscle shortens
- Rate of wing beat
What is partial migration?
Where some members of a population remain in the same breeding area whilst others of the population migrate overwinter.
Birds time their arrival to the breeding area to correlate with what?
An abundance of food in the breeding area.
What axis is migration mostly observed on?
North-South axis
Would bird species in seasonal environments be more or less likely to be migratory? Why?
- More likely
- Variation in food availability by season
Travelling overland and within continents is migratory behaviour seen in what type of migratory birds?
Short-distance migrants
Crossing seas, travelling between different continents, and using a flyway is migratory behaviour seen in what type of migratory birds?
Long-distance migrants
Give one example of a short-distance migratory bird.
Waxwings (Birds from Bombycilla genus)
Give one example of a long-distance migratory bird.
Common cuckoo (Cuculus canorus)
What are the three main flyways that are used by long-distance migratory birds?
- The Americas flyway
- The African-Eurasion flyway
- The East Asian-Australasian flyway
Define ‘Adaptation’.
A trait of an organism that increases it’s chances of survival and reproduction within a particular environment.
Define ‘Natural Selection’.
The differential survival and reproduction between individuals based on their particular phenotypes/traits
What process drives evolution?
Natural selection
What three things need to exist in a group of organisms for natural selection to occur?
- A heritable genetic code
- A struggle for survival
- Variation between individuals in terms of phenotypes
What are the three types of natural selection?
- Directional selection
- Stabilising selection
- Disruptive selection
Describe directional selection.
What it is, population curve, mean/median, evolutionary impact
Indidividuals of a population with an extreme of the phenotypic range are are favoured.
Population frequency curve regarding phenotype is shifted in a single direction.
Changes mean of phenotype
Dramatic evolutionary impact - can lead to speciation
Describe stabilising selection?
What it is, population curve, mean/median, evolutionary impact
- Individuals with intermediate variants in the phenotypic range are favoured
- Population frequency curve stabilises
- Maintains mean/ refines phenotype
- Non-dramatic evolutionary impact
Describe disruptive selection.
What it is, population curve, mean/median, evolutionary impact
- Individuals with the smallest and largest values of the phenotypic range are favoured
- 2 peaks are formed on the population frequency curve (M-shape)
- Changes mean and/or median
- Dramatic evolutionary impact - can lead to speciation
Which types of natural selection are more likely to cause speciation?
Directional selection and Disruptive selection.
Name and define two types of migratory behaviour?
- Obligate migration | Aspects of migratory behaviour are under genetic control mediated by changes in day length
- Facultative migration / irruptive migration | Migration is a direct response to conditions
What are some characteristics of obligate migrants and their migration?
- Consistent sacricity of food in winter in breeding areas
- Leave before food runs out
- Consisten timing, direction, and distance
- Consistent behaviour
- Long distance
What are some characteristics of facultative migrants and their migration?
- Food available in winter varies
- Variation in number of individuals that migrate
- Variable distances, timing, and direction
- Variable behaviour
- Short distances
What is the most common migratory pattern of all migratory animals?
Partial migration
If individuals within a bird population began to show migratory behaviour, and this increased their overall fitness, what would you expect to see over the next few generations of the population?
The entire population becoming migratory
What is the scientific name for the Blackcap?
Sylvia atricapilla
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What is migratory restlessness?
A behaviour seen in which birds in captivity mimic migratory behaviour seen in wild birds.
What is migratory inclination?
The predisposition of individuals to migrate or stay sedentary.
Crossing of migratory and sedentary birds showed what?
Migratory inclination can be bred into non-migratory birds and therefore must have a genetic component.
Name some changes seen in migratory behaviour of birds and what factors may be driving these?
Changes:
- Later departures in autumn
- Early arrival in spring
- Shortened distances
- Changes in overwintering grounds & direction
Factors:
- Warmer winters (climate change?)
- Availability of garden plants with winter fruit
- Humans feeding birds
- Saving energy and time (shorter distances)
- Earlier breeding may increase fitness
What is homeostasis?
An organisms physiological processes that regulate an optimal internal environment.
Name some of the aspects of physiology that are regulated.
- Temperature
- pH
- Concentrations
- Osmotic pressure
- Redox potentials
When would a homeostatic response occur?
If a change in the external environment deviates the internal environment from optimal.
What are endotherms?
Organisms that internally maintain a constant body temperature.
What are ectotherms?
Organisms with an internal temperature that relies on external sources.
What type of organisms can tolerate a substantial lowering of body temperature?
Ectotherms
What is metabolic rate?
The energy used by an organism over a particular unit of time.
What is basal metabolic rate (BMR)?
The amount of energy used by an endothermic organism whilst at rest that maintains basic cell function.
Basal metabolic rate can only occur in what zone?
The thermoneutral zone (range of temperatures in which BMR can be maintained)
What effect does extremely high or low temperatures have on enzyme activity?
- High temperatures (hyperthermia) may lead to denaturation of enzymes
- Low temperatures (hypothermia) reduces the enzyme activity, and therefore enzyme-mediated reactions also decrease
When under the most physiological stress, what type of metabolic rate is occuring?
Summit metabolic rate
Give 3 examples of ways birds ensure energy is available for migration?
- Avoid cold and heat stress | preserve energy
- Pre migratory fattening with lipids (produce water when metabolised)
- Panting | reduces body temperature
- Flying at higher altitudes | cooler temperature
- Changing feather covering and fat layers | reduce energy used for thermoregulation
- Huddling | especially at cold stopovers, conserve heat energy
- Controlled hypothermia | reduces energy expenditure and rebuilds atrophied tissue
What three internal compasses do birds have that help them navigate directionally during migration?
- Magnetic
- Stars
- Sun
Desribe how birds use magnetoreception?
- Cryptochromes (photoreceptors) in their eyes can detect the orienation of magnetic field lines.
- Iron-rich structures in the beak responds to changes in magnetic field intensity
What do birds need to be able to use their internal star compass?
- A clear sky
- Experience of the night sky previously
What 2 roles does the Sun have in bird migration?
- Helps deduce direction (limited)
- Regulates internal clock
