Lecture 29- Mammal Adaptations Flashcards
Mammals in the north are in ____ diversity
Low
Describe the type of mammals in the boreal
- 70 species of which 50 are herbivores
- Artiodactyla = ungulates
- Rodentia = rodents
- Lagomorpha = hares, rabbits, pikas
Describe the types of mammals in the Arctic
- Terrestrial and marine
- 30-50 mammals in the circumpolar Arctic
- 14% lagomorphs
- 40% rodents
- 33% carnivores
- 13% ungulates
- 8-10 seal species and about 9-12 whale species
What are some morphological conditions for adaptations for mammals in the north?
- Body size (Bergmanns rule)
- Colouration (Glogers rule)
- Limb size (Allens rule)
What are some morphological adaptations for mammals?
- Thick insulating coat
- Prescence of a longer baculum
- Low foot loading
What are the two types of coats mammals have during the year?
- Short, thin summer coat = usually brown
- Long, thick winter coat = usually white
What is an example of a species that have hollow hairs?
Caribou
Polar bears have ____ hair because ______
- Translucent
- It reflects light (appears white) which allows for better absorption of thermal radiation to black skin
Other than a longer baculum, what are some other sexual adaptations in mammals?
- Delayed implantations
- Allows seperation between mating and giving birth
- Allows mating during season when mates are accessible
Why do is a longer baculum beneficial in mammals higher north?
- May increase copulation success
- Evolved to compensate for seasonality of resources and lower population density
What is a benefit to lower foot loading?
- Lower foot loading = high foot surface area
- Spreads lower body mass across a larger area
- Skin less in the snow = saves energy and move efficiently
What is the downfall to higher foot loading?
- Sink further in the snow
- Present in species poorly adapted to snow travel
What are some behavioural adaptations for mammals?
- Migration (mostly caribou)
- Basking (seals and walruses)
- Synchronous birthing (caribou, lemmings)
- Food caching
- Subnivean living
- Snow coping methods
What is basking?
Angles body towards the sun which warms the body after cold dives
Predator swamping reduces the probability that ______
Any one individual will be prayed on
What is synchronous birthing?
Majority of the young are born within a short time frame
What is food caching?
Store excess food for future
What are the two types of food caching?
- Scatter hording = many small caches (reduces likelihood of stealing and requires spatial memory)
- Larder hoarding = one large cache (kept near den of animals, must be defended)
What are some benefits to subnivean living?
- Tunnels, air circulation = space to live, feed in
- Access to plants for food
- Provides insulation from cold
- Protection from predators
- Insulates fluctuations in air temperature
- Hiemal threshold
Deeper snow =?
Higher density =?
- More insulation
- Less insulation
What is the hiemal threshold?
Snow thickness at which subnivean environment is protected from temperature fluctuations
Describe some snow coping methods
- Utilize food above the snow (browsing)
- Digging into the snow for food
- Specialized locomotion
- Trail making
- Habitat selection within winter range (choose most suitable snow conditions)
Describe the snow and lemming cycles experiment
- Tracked lemming density throughout trapping
- Also tracked snow conditions
What are the results of the snow and lemming cycle experiment?
- Highest lemming density every 3-4 weeks
- Large fluctuations in snow conditions
- Over time snow depth increased, hiemal threshold reached sooner
- Higher snow depth = higher lemming densities
- Higher snow density = lower lemming densities
- Snow characteristic influenced population cycles
