Ch 14 Interactions in Ecosystems 14.1 Habitat and Niche Abiotic + biotic factors Ecological niche Phys, chem, bio factors species needs to survive/reproduce Niche includes: food, all abiotic factors, and behaviors of species Ex. Bee vs butterfly

Competitive Exclusion If 2 species are competing for same niche then 1 that is better suited gets it (other move/dies) Niche partitioning- use different parts Evolutionary response- divergent evolution to use different resource Ecological Equivalents In different geological region/habitats species inhabit similar niches

14.2 Community Interactions Competition Interspecific: 2 different species compete same resources Intraspecific: 2 of same species compete Predation Hunting/ killing prey Natural selection of both predator (how well obtain food) and prey (can they avoid being eaten)

Symbiosis: 2 or more species in direct contact Mutualism +/+, both benefit Ex: bee and flower Commensalism +/no effect, one benefits other not affected Ex. Shark and remora Parasitism +/-, one benefits and other is harmed Ex. Dog intestines and worms

14.3 Popln Density and Distribution = # individuals / area (m2) Popln distribution Clumped: in groups Uniform: territory Random: no pattern Clumped dispersion Uniform Random

Survivorship Curves Type I Type II Type III Lots of individuals/ live long Ex. Large mammals Type II Survivorship rate = at all ages Ex: birds, small mammals, reptiles Type III High birth rate, but few survive Ex. Invertebrates, fishes, amphibians, plants

14.4 Popln Growth Patterns Changes to Popln + Births & Immigration (come in) Deaths & Emmigration (exit) Exponential Growth (J-curve) Resources abundant Popln grows rapidly Logistic Growth (S-shaped) Resources limited Slow growth, exponential growth, stabilizing

Density-dependent limiting factors Carrying capacity Max amt for environment Popln crash Dramatic decline popln Density-dependent limiting factors Affected by # of individuals in area Competition, predation, disease, parasitism Density-independent limiting factors Doesn’t matter popln density Weather, natural disasters, human impacts

14.5 Ecological Succession biological changes/ sequences to regenerate 1 2 3 4 or reestablish damaged community Primary Succession: uninhabited ecosystem 1: 0-15yrs, bare rocks covered moss and lichen 2:15-80yrs, shrubs begin to grow 3:80-115yrs, soil thickens to allow tree growth 4:115-200yrs, diff tree species in direct sunlight

Secondary Succession: Reestablishment of a damaged ecosystem, no end to it! 1 2 3 4 1: 0-2yrs, weeds/ grasses 2: 2-18yrs, grasses and shrub, saplings 3: 18-70yrs, pines and young hardwoods 4: 70-100yrs, mature forrests