Transcript Ecology
Ecology Behavior, Communities, Ecosystems Behavioral ecology Scientific study of behavior in natural environments from an evolutionary perspective Behavior • What an animal does • How it does it • Usually in response to stimuli from the environment Cost-benefit analysis to determine whether a behavior is adaptive Contribute to direct fitness Animal’s reproductive success measured by the number of viable offspring When benefits outweigh costs, behavior is adaptive Behavior Results from the interaction of innate behavior and environmental factors Learned behavior • Behavior is modified in response to environmental experience Imprinting Establishes a parent-offspring bond Ensures that the offspring recognizes the parent Selfish behavior Increases individuals chances of survival Social groups; selfish herd; dominance hierarchies Altruistic behavior Sacrifice for the good of the group Bees Inclusive fitness – passing on the genes that make organism care for relatives Social behavior Adaptive interaction, usually among members of the same species Animal communication involves exchange of recognizable signals Pheromones are chemical signals that convey information between members of a species Are mating and parental behavior under genetic influence? Those that can attract more mates, reproduce more, pass on those genes Parenting is an energy consuming role, but it ensures offspring survive to pass on genes What is the relationship between ecology and evolution? The reason species evolve is due to environmental pressures Food is scarce – maybe better digestive tract or teeth help some survive – they pass on those traits 5 factors that shape community structure Interaction between climate and topography Food Adaptive traits of species Species interactions Pattern of population size Ecological niche Distinctive lifestyle and role of an organism in a community Takes into account all abiotic and biotic aspects For example, an organism’s habitat is one parameter used to describe the niche Interspecific competition – between 2 populations Requirements of 2 species are close, but never exactly the same Competitive exclusion principle Two species cannot occupy the same niche in the same community for an indefinite period One species is excluded by another as a result of competition Resource partitioning Predation Defenses Camouflage Warning coloration Mimicry Moment of truth Predator response to prey Mimicry Camouflage Symbiosis Mutualism • Both partners benefit Commensalism • One partner benefits and the other is unaffected Parasitism • One partner benefits while the other is harmed Keystone species Present in small numbers but are crucial in determining the species composition and ecosystem functioning • Beaver – creates new ecosystems that animals rely on Dominant species Affect the community because they are so common Ecological succession Primary succession • Occurs in an area not previously inhabited Secondary succession • Occurs where there is a preexisting community and wellformed soil Energy flow through an ecosystem Ecological pyramids Express the progressive reduction in numbers of organisms, biomass, and energy found in successive trophic levels Biomagnification Gross primary productivity (GPP) Rate at which photosynthesis captures energy Net primary (ecosystem) productivity (NPP) Energy that remains after plants and other producers carry out cellular respiration Carbon cycle Carbon dioxide is the most important gas Carbon enters plants, etc., as CO2 Cellular respiration, combustion, and erosion of limestone return CO2 to the environment Nitrogen cycle Five steps • Nitrogen fixation – converting N2 to ammonia • Nitrification – convert ammonia to nitrates (which plants use) • Assimilation – nitrogen taken by organism to make organic compounds • Ammonification – ammonia ions • Denitrification – ammonia to N2 Hydrologic cycle Renews the supply of water Involves an exchange of water between the land, ocean, atmosphere, and organisms Water enters the atmosphere by evaporation and transpiration Water leaves the atmosphere as precipitation