Chapter 50: Ecology I. The scope of ecology A. Ecology is the scientific study of the interactions between organisms and their environments 1. very difficult to conduct experiments and control variables 2. models used frequently 3. multidisciplinary 4. includes biotic and abiotic components *short-term (ecological time) interactions could have long-term (evolutionary time) effects through natural selection B. Ecological research ranges from the adaptations of organisms to the dynamics of ecosystems 1. organismal ecology: studies the behavioral, physiological, & morphological ways individuals meet abiotic environmental challenges a) distribution is limited by tolerance 2. Population ecology: studies groups of individuals of the same species living in a particular geographic area a) questions concern factors that affect population size and composition 3. Community ecology: studies all organisms that inhabit a particular area a) questions concern predation, competition, disease and other ways in which interactions among organisms affect community structure and organization 4. Ecosystem ecology: studies all abiotic factors as well as communities of organisms in an area a) questions concern energy flow and chemical cycling among the abiotic and biotic components C. Ecology provides a scientific context for evaluating environmental issues II. Abiotic factors of the biosphere (sum of all earth’s ecosystems) A. Climate and other abiotic factors are important determinants of the biosphere’s distribution of organisms 1. global and regional patterns reflect differences in climate and other abiotic factors 2. temperature, humidity, salinity, and light influence distribution of organisms B. Major abiotic factors 1. temperature a. most organisms are unable to regulate their body temperature precisely b. 0-45 degrees C are critical temperatures 2. Water 3. Sunlight a. provides the energy that drives all ecosystems b. physiology, development and behavior of many animals and plants are sensitive to photoperiod 4. Wind—evaporation, transpiration, etc. 5. rocks and soil 6. periodic disturbances (Catastrophic) --Climate and topography have the greatest effect on species distribution 1) major components of climate: water, temp, light, wind 2) determined by annual temperature averages, rainfall 3) results in various “biomes” around the world CONCEPTS OF ORGANISMAL BIOLOGY (PHYSIOLOGICAL, MORPHOLOGICAL & BEHAVIORAL MECHANISMS THAT ALLOW SPECIES TO MEET THE CHALLENGES OF THEIR ENVIRONMENT REGULATORS & CONFORMERS—REFERS TO MECHANISMS USED TO ACHIEVE HOMEOSTASIS 1) REGULATORS USE BEHAVIORAL AND PHYSIOLOGICAL MECHANISMS (SUCH AS PACIFIC SALMON, USING OSMOREGULATION TO CONTROL INTERAL SALT CONCENTRATIONS), WHICH CONSUMES ENERGY 2) CONFORMERS ALLOW CONDITIONS WITHIN THEIR BODY TO VARY WITH EXTERNAL CONDITIONS, EVEN IF THE RESULT IS DEATH (*MANY SPECIES DO A LITTLE OF BOTH, INCLUDING US. CAN YOU THINK OF AN EXAMPLE?) THE PRINCIPLE OF ALLOCATION—STATES THAT EACH ORGANISM HAS A LIMITED AMOUNT OF ENERGY THAT CAN BE ALLOCATED FOR OBTAINING NUTRIENTS, ESCAPING PREDATORS, COPING WITH ENVIRONMENTAL FLUCTIONS, ETC. (AND IS THEREBY UNAVAILABLE FOR OTHER FUNCTIONS) SHORT-TERM RESPONSES MUST OPERATE WITHIN THE EVOLUTIONARY FRAMEWORK 1) PROXIMATE CAUSATION (OF A BEHAVIOR OR CHARACTERISTIC) ADDRESSES THE IMMEDIATE REASON (i.e., WHAT ARE THE DIFFERENCES IN THE PINEAL GLAND OF NOCTURNAL VS. DIURNAL ORGANISMS?) 2) ULTIMATE CAUSATION OF THE SAME BEHAVIOR/CHARACTERISTIC ADDRESS HOW NATURE SELECTED THAT MECHANISM INSTEAD OF SOME OTHER BEHAVIOR OR CHARACTERISTIC PHYSIOLOGICAL RESPONSES MAY OCCUR OVER MANY TIME SCALES (SECONDS TO WEEKS) --REGULATION, HOMEOSTASIS ARE FOUNDATION RESPONSES --ACCLIMATION INVOLVES SUBSTANTIAL BUT REVERSIBLE CHANGES THAT SHIFTS A TOLERANCE CURVE AND IS GENERALLY LIMITED BY A RANGE OF CONDITIONS A SPECIES NATURALLY EXPERIENCES MORPHOLOGICAL RESPONSES ALTER FORM OR INTERNAL ANATOMY --MAY DEVELOP OVER THE LIFETIME OF AN INDIVIDUAL (MORE LIKELY ASSOCIATED WITH PLANTS) OR ACROSS GENERATIONS BEHAVIORAL RESPONSES MAY BE INSTANTANEOUS AND ARE EASILY REVERSED (REFLEX, MIGRATION)