Friday, January 15, 2016

r selection, K selection

In class, we discussed two types of reproduction strategy, r selection and k selection. R selection is when a population is far below the carrying capacity of an unstable environment. R-strategists are identified by short life expectancy, early maturity, small size, strong sex drive, and low intelligence. They often produce many cheap offspring and give them little care. R-strategists aim to make use of ephemeral resources and ensure that at least some offspring survive in unstable environment. Examples for r-strategists are bacteria and frogs. K selection is when a population is at or near the carrying capacity of the environment. K-strategists are identified by long life expectancy, late maturity, strength, weak sex drive, and high intelligence. They often produce few expensive offspring and give them much care. K-strategists tend to favor individual that slowly developing in order to successfully compete for resources. Examples for k-strategists are human, cat, and dog.


The survivorship curve has three different types: Type I, Type II and Type III. Type I represents k-strategist. It shows that k-strategists lost most of the individuals quickly but a few survived individual live much longer than the rest. Type III represents r-strategist. It shows that the r-strategist lost the individuals eventually as age increases. Type II shows the curve between Type I and Type II.


After the “Household pets and pests” activity, we concluded that pets tend to be k-strategist and pests are r-strategists. However this is not universally true as some people have pets that are r-strategists. For example, my friend has fish ,which is r-strategist, as pets. Species with k selection strategy tends to have more intimate relationship with human as they live longer and has higher intelligence than species with r selection strategy. 


2 comments:

  1. Great explanation.
    From this it can be seen how crucial the males are in driving this process via the immense success derived from sexual reproduction. Not for the males, humans probably would not be existing today, for that matter most complex organisms like birds and mammals.

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