Population Level Population Growth – positive or negative changes can help in understanding nature of response Challenge is recognizing multiple factors might be involved Example – Science Focus p. 110
Why is Sea Otter Population Increase Slow? Slow reproduction Increase # orcas Cat parasites via kitty litter Toxic algal blooms (urea from fertilizer) PCBs & other pollutants (otters as biomagnifiers)
Recognizing Strategies of a Population: r-selected and K-selected species
Populations fluctuate around K or do not reach it? Why?
Community Level Role of Interactions Competition Predation Parasitism Mutualism Commensalism Have proximate (ecological) and ultimate (evolutionary) impacts
Competition – Evolutionary Influence Prevent species from reaching carrying capacity Change niche (realized niche) - barnacles Competitive exclusion