Lecture Notes I Part 7.doc

Evolution by changes in the timing of growth and development Allometry: change in shape during growth due to differential growth rates Heterochrony: evolution change in the rate or timing of development Paedomorphosis: retention of juvenile features in the adult stage Competition ?The use or defense of a resource by one individual that reduces the availability of that resource for other individuals? Intraspecific Competition: Between individuals of a single species Interspecific Competition: Between individuals of different species ?Resource? Something that is used by an organism or a population that can lead to increased growth rates as its availability in the environment is increased Increased resources = increased growth rates Resources are used by individuals or populations for their own maintenance and growth NOT resources Conditions: influence the ability to utilize resources but are not themselves used Classification of Resources External: ?external? to the system (ex. Sunlight) Indirect link Resources generated in the ecosystem and abundance is affected by the consumer (food ( animals or plants) Direct link ?Limiting Resources? As a population grows the need for resources increases and its abundance decreases Eventually the population reaches the resources ?carrying capacity? K and it is said to be at equilibrium when N (population) is equal to K Usually not so level like this and more ?cyclic? (sinusoid) ?Leibig?s Law of the Mininum? When multiple resources are needed, the least abundant will control the rate of growth Resource Food Light Water Nurtients Shelter Space Mates Breeding Sites Nesting Sites Interspecific ( ( ( ( ( ( ( ( Intraspecific ( ( ( ( ( ( ( ( ( The resource may be abundant at times but the organism may also not be able to fully utilize it and it may, thus, be limited