Chapter 8 Community Ecology: Structure, Species Interactions, Succession, and Sustainability Miller – Living in the Environment 13 th Edition

ECOTONE transition zone or boundary between two ecosystem, merging area may be narrow or sharp (b/n woodland- grassland) may be gradual or wide (estuary to ocean) greater number of species along with greater pop. density in an ecotone than in either single ecosystem

Most Species Rich Environments Tropical rainforests Coral reefs The deep sea Large tropical lakes

What are Edge Effects? EDGE EFFECTS = changes occurring at boundaries or edges b/n habitats, there are changes in community structure and physical properties (sunlight, temp, wind) favorable habitat for edge species (ex. Deer)

Roles of Species in Ecosystems native non-native indicator keystone

Native and Non-native Species Native species Species that normally live and thrive in a particular ecosystem Non-native (exotic or alien) species Species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem Cane toads, Zebra Mussels, Kudzu, Water Hyacinth

Indicator Species Species that serve as early warning of environmental damage to an ecosystem(most sensitive), environmental health gauge Birds (canary in a coal mine) Fish (trout) Amphibians Herps

Habitat loss Drought Pollution UV radiation Parasitism Over-hunting Diseases Immigration or introduction of predators or competitors sperm Eggs Sexual reproduction Fertilized egg development Organ formation Egg hatches Tadpole develops Into frog Young frog Adult frog (3 years) Indicators of thing like...

Keystone Species Species that play roles affecting many other organisms in an ecosystem Strong interaction with other species affect health and survival of species species whose removal would effect many others as they play a critical role loss of species can result in population crash or extinction critical roles: involve pollination, predation, nutrient recyclers

Species Interactions competition predation parasitism mutualism commensalism

Competition Intraspecific competition – competition between members of the same species Gain a competitive advantage (Plants) Chemical inhibitors Seed dispersal Territoriality (Animals) Patrol or mark an area Defend an area

Competition Interspecific competition – competition between members of two or more different species Abundant commonly used resources (food, sunlight, water, soil nutrients, space, nesting sites) Fundamental niche Limited resources Overlap of fundamental niches

Competitive Exclusion Principle The niches of two species cannot overlap completely or significantly for very long. one species excluded/eliminated from niche by competition for limited resources

Paramecium p. 174 Paramecium Experiment = grown separately, then together RESULTS = two species needing same resource CANNOT coexist due to limited resources, niches of two species CANNOT overlap completely or indefinitely

HOW DO WE SURVIVE????

Resource Partitioning organisms access slightly different resources to coexist (ADAPT & EVOLVE) use resources in different ways, from different areas, or at different times thus resources are partitioned EX. Spruce forest warblers: distinct feeding habits

Resource Partitioning Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion of the spruce tree and by consuming somewhat different insect species.

Number of individuals Resource use Species 1 Species 2 Regionof niche overlap Species 1 Species 2 © 2004 Brooks/Cole – Thomson Learning Resource Partitioning Niche Specialization

Predator – Prey Relationship Predation – members of one species (predator) feed directly on all or part of a living organism of another species (prey). Benefits from reducing prey population Gives remaining prey greater access to food supply Can improve the genetic stocks of the prey population

PREDATOR STRATEGIES include: Pursuit and Ambush ~ traits that increase hunting efficiency (ex. Speed, intelligence, camouflage, attractions, trickery)

Predator Tactics Pursuit Cheetah Eagle Wolves Ambush Preying Mantis Snowy Owls Humans

Prey Strategies Escapism ~ traits that increase ability to FLEE! Sensory alertness ~ sight/smell alerts of predators lurking

Protective outer armor ~ shells, spines, thorns, bark for protection

Unique adaptations lizard tails that break away Camouflage chameleons, arctic fox

Chemical Warfare ~ poisons (toxic, irritating, bad tasting) excreted when threatened Behavioral Strategies ~ scare off predators by behavioral activity (puff body, spreading wings, herds, mimicry)