Chapter 4 Flashcards
Weather
the variation in temperature and precipitation over periods of hours or days.
Climate
the typical atmospheric conditions that occur through the year, measured over many years.
Large-scale spatial variation
caused by factors such as climate, land topography, and soil type
small scale variation
generated by factors such as plant structure and animal behavior.
Phenotypic trade-off
a situation in which a given phenotype experiences higher fitness in one environment, whereas other phenotypes experience higher fitness in other environments.
Phenotypic plasticity
the ability of a single genotype to produce multiple phenotypes.
Acclimation
which is an environmentally induced change in an individual’s physiology, can also be relatively rapid.
Hermaphrodites
individuals that produce both male and female gametes; individuals are able to fertilize their eggs with their own sperm (i.e., they are self-compatible).
Inbreeding depression
the decrease in fitness caused by matings between close relatives due to offspring inheriting deleterious alleles from both the eggs and the sperm.
Because of this cost, some species wait until self-fertilization becomes the last chance for reproduction.
Dormancy
a condition in which organisms dramatically reduce their metabolic processes.
Diapause
involves a partial or complete physiological shutdown in response to unfavorable conditions; common in insects.
Example:
Insects facing drought conditions enter diapause by dehydrating themselves. Some form an impermeable outer layer to prevent further dessication.
Hibernation
individuals reduce the energetic costs of being active by lowering heart rate and decreasing body temperatures; common in mammals.
Example:
During winter, chipmunks slow breathing and heart rates and reduce body temperature to close to 0C.
Torpor
a brief period of dormancy in which individuals reduce activity and body temperature; common in birds and mammals.
Example:
The West Indian hummingbird loses much of the heat it generates to cold temperatures. To save energy, the bird enters torpor when it is resting at night.
Aestivation
the shutting down of metabolic processes during the summer in response to hot or dry conditions. Well-known examples include snails, desert tortoises, and crocodiles.
Foraging decisions
Foraging is a plastic behavior because different feeding strategies represent different behavioral phenotypes.
Since resources vary in space and time, no single foraging strategy can maximize an animal’s fitness.
Animals must determine where to forage, how long to feed in a certain patch of habitat, and which types of food to eat.
Central place foraging
foraging behavior in which acquired food is brought to a central place (e.g., a nest with young birds).
As an individual forages farther from the central place, it finds greater amounts of resources, but this increases energy costs and the amount of food the individual must bring back.
As an individual feeds and collects prey, it becomes increasingly difficult to hold or consume the next prey item (i.e., there are diminishing benefits over time).
What do foraging decisions depend on?
the time needed to travel round-trip to site with resources (i.e., traveling time) and the time spent obtaining food at a site (i.e., searching time).
At sites farther away, birds should spend more time searching for food and bring back more food to offset the extra travel time.
Risk-sensitive foraging
foraging behavior that is influence by the presence of predators.
Example:
Creek chub feed on tubifex worms, but locations with worms also contain more predators.
Research has found that past a certain threshold of resource abundance, creek chub will risk feeding in an area with predators.
Below that threshold, creek chub avoid areas with predators.
Handling time
the amount of time that a predator takes to consume a captured prey.
The energy benefit of a resource item divided by the handling time is the amount of energy gained per unit time.
A predator should always eat the prey species that provides the highest amount of energy gained per unit time.
If the highest energy prey is rare, the animal should include less profitable items in its diet.
Diet mixing
Some foragers consume a varied diet because one type of food might not provide all of the necessary nutrients.
Examples:
Humans combine food items to consume all essential amino acids.
Nymphs of the American grasshopper grow faster when provided a mixed diet of plants, even though each of the plants is relatively low quality.
