Presentation on theme: "Energy Budgets Class Notes 2:4. Objectives Understand the Principle of Allocation Describe the differences between r-strategists and k-strategists Explain."— Presentation transcript:
Objectives Understand the Principle of Allocation Describe the differences between r-strategists and k-strategists Explain how this information relates to Endangered Species
Suppose you have a job and earn a predictable amount of money each week Energy Budgets
How should you spend it? Money that you spend on one activity will not be available for other expenditures F amily needs? S ave for college? A bacon double-cheeseburger? C lothes? M usic? S ports? C omputer games?
Few organisms have unlimited supplies of energy Most have some typical, average amount of energy available on a day-to-day basis
How should this energy be expended? T o maintain body heat? o care for offspring? o activate enzymes? Aiphanes T o maintain a heartbeat? o fight infections? S hould I dig a burrow? O r is a shell a better idea? S hould I fly south for the winter? H ow about growing some needle-like spines like this Aiphanes palm?
The Principle of Allocation How much energy should a plant expend on defensive chemicals?
Or to build a shell, or a nest? Is a long migration each year a good use of available energy or not? Chambered nautilus
Or is it a better use of energy to have fewer offspring and take better care of them?
The Principle of Allocation Energy expended for one life activity is not available to support other life activities
r-strategists and k-strategists In terms of energy budgets, we classify some organisms as r-strategists Oysters, tapeworms, dandelions, weeds, and most insects are good examples of r-strategists
k- strategists Whales, gorillas, rhinos, elephants, and redwood trees are examples of k-strategists Still other species fall somewhere in between Other organisms are k-strategists and exhibit very different types of energy budgets
What Do r-strategists Have in Common? Grasses, ants, wildflowers, weeds, fruit flies and clams exemplify traits commonly seen in r-strategists
S mall body size hort lives M ature early L arge numbers of young T hey are good at quickly colonizing new habitats B ut they invest little energy in caring for their young
This tapeworm exemplifies an r-strategist’s approach to species survival It produces hundreds or thousands of eggs and offspring most of which will never survive
As long as just two or three offspring manage to survive, the species will continue to exist r-strategists are often said to be careless of the individual
k-Strategists Gorillas, rhinos, orangutans, and whales are classic examples of k-strategists
Characteristics Large size Long lives Many years before maturity Do best in stable and undisturbed environments
k-Strategists k-strategists produce few young at long intervals think of a whale with one calf at a time k-strategist parents expend a great deal of energy to care for their young and ensure their survival Do males and females of the same species necessarily have the same energy budgets?
Energy Budgets in Plants How much energy should be expended on spines? Do plants exhibit energy budgets? Snake cactus
How much energy should be expended on seeds? Should energy be spent producing an orange or an apple or not? Cycad
How does a vine differ from a tree in its energy allocations? Energy Budgets in Plants Bamboo
This tree is expending a lot of energy on all of these mangos Does it gain any advantage as a result?
270,000 plant species on earth expend a lot of energy on flowers Capparis
Why? Answer: To entice hummingbirds and insects to help them reproduce
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