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Published byRoss Harold Stevens Modified over 9 years ago
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a. When individuals produce more offspring at a time B. Reproduce more often C. Reproduce earlier in life Reproducing earlier in life has greatest effect
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Smaller organisms like bacteria and insects usually have shorter generation times and can reproduce when they are only a few hours or days old. As a result: These populations grow more quickly! Larger organisms take longer to sexually mature and have a lower reproductive potential.
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Grow faster and faster Large number of individuals are added to the population in each succeeding time period For this to occur must have plenty of food, space, no competition/predators “J” shaped curve
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IF ONE DOG HAS 6 PUPPIES: EACH PAIR OF DOGS IN THAT GENERATION HAS 6 PUPPIES THERE WILL BE 18 DOGS IN THE NEXT GENERATION. IF EACH OF THOSE 18 PUPPIES MATES AND HAS 6 PUPPIES, THE NEXT GENERATION WILL HAVE 54 DOGS, AND SO ON………………….
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Natural conditions not ideal or constant Rarely grow at reproductive potential Eventually reach Carrying Capacity Resource Limits Competition Within a Population
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Maximum population that the ecosystem can support indefinitely May increase beyond but cannot stay at that size Ex. Rabbits May be briefly exceeded But not sustained
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A. Originally no rabbits in Australia, introduced in 1859 B. Numbers increased rapidly C. No predators, no competition, plenty of food (vegetation) D. Eventually, disease and starvation caused crash E. Over time, vegetation recovered F. Rabbits increased again G. Continued increases and decreases, but less dramatically
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Competition occurs in populations when members use the same resource in the same way As fewer resources become available, competition among individuals increases and the population reaches carrying capacity. Population density = number of individuals per unit area
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Population is limited dependent on the size of the population. Characteristics: A. Death occurs more quickly in crowded populations B. Densely packed together C. Rapid growth Examples: limited resources, disease, predation
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Certain percentage of population dies regardless of population’s density. Examples: Severe weather Natural disasters
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The unique ROLE of a species in an ecosystem. It is NOT a PLACE (that would be a habitat) An organism’s niche includes: A. Physical home B. Environmental factors necessary for survival C. All interactions with other organisms
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