Population Growth

Unchecked growth! Can one bacterial cell take over the world????? No. too many factors control or influence a populations size. Resources- food, air, waste removal, proper space, predation. Changing conditions- temp, salt, oil spills!! Both abiotic and biotic factors control population size. Environments can only support a certain number of individuals before conditions begin to decline and limit or reduce the population. Terms to know….

Terms to know Factors that control population growth Carrying Capacity- the largest population size that can be supported by the area. Limiting resource-required for growth but in small amounts Abiotic and biotic features Competition- intra and inter specific Self Regulating Population- growth rate is limited by the size of the population

Question An aquarium owner decides to get rid of his aquarium and releases a few non-native sea urchins into the ocean nearby. Many years later, a scientist studying that area notices that the population of native sea urchins has drastically decreased. What may have occurred?

Predator and Prey Part of self regulating a population Too many predators- prey decreases Predators leave Too few predators- prey increases Predators move in

Strategies Efficient hunter Lure camouflage Speed camouflage defense Page 192 Speed camouflage defense

Symbiosis Close living association between 2 species Host and symbiont (smaller one) Commensalism= +, 0 Parasitism= +, - Mutualism- +, + Zooxanthellae and coral in module 4. Commensalism Parasitism Mutualism- the mutualism between xooxanthellae and coral is sometimes referred to as co-evolution. Termed ‘co-evolution-… meaning that they must have evolved at the same time b/c One could not have survived. This is tough because the probability of 2 mutually dependent organisms evolving simultaneously is near impossible. And yet, we see so many of these relationships today. The probability that so many of these relationsips could result from co-evolution is a HUGE statistical impossibility. As an example, there are so many ‘cleaner’ and cleaned’ relationship in the marine environment. Cleaner fish and shrimp set up cleaner stations to service many species of fish to be cleaned. Tehse fish voluntarily open their mouths of lift their fins to accommodate the cleaner. Others wait in line to be cleaned.