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Life strategies

Life strategies. Organisms may trade-offs to maximize the number of offspring that survive. They use different life strategies . The strategies are usually correlated to the type of environment they live in.

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Life strategies

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  1. Life strategies • Organisms may trade-offs to maximize the number of offspring that survive. • They use different life strategies. • The strategies are usually correlated to the type of environment they live in. • In unstable environments the strategy is to reproduce close to biotic potential and produce as many offspring as possible in a short period of time. In more stable environments populations live close to carrying capacity, they have fewer offspring and provide their young with more care, investing their energy in ensuring their offspring reach reproductive age.

  2. r- and K-selected Strategies • Species that have an r-selected life strategy live close to their biotic potential (r). • In general these organisms: • Have a short life span • Become sexually mature at a young age • Produce large broods of offspring • Provide little or no parental care to their offspring

  3. r-selected strategies • Ex. Insects, Annual plants, Algae • They take advantage of favorable conditions such as the availability of food, sunlight and warm temperatures and reproduce quickly. • They experience exponential growth during the summer and die in large numbers at the end of the season.

  4. K-selected strategies • Organisms with a K-selected strategy live close to the carrying capacity (K) of their habitats. In general these organisms • Have a relatively long life span • Become sexually mature later in life • Produce few offspring per reproductive cycle • Provide a high level of parental care • Ex. Mammals and Birds

  5. Organisms tend towards r or K-selected life strategies, but most populations are somewhere in between the two groups. • For example the balsam fir is large and lives for many years yet produces hundreds of gamete-bearing seeds in cones.

  6. Connection to Ecology • Whether an organism is r- or K-selected also depends on the population you are comparing it to. • Rabbits are K-selected when compared to mosquitoes, but r-selected when compared to bears. • Scientists use life strategies to predict the success of a population in a given environment. Ex. Antarctic fur seals.

  7. ASSIGNMENT • Read pages 517 and 518 from McGraw Hill Ryerson Text • Complete page 527

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