Physical and Chemical Factors 1 Temperature a Global pattern Total annual insolation solar radiation that hits and is absorbed by surface of the Earth land and sea o Highest at equator lowest at poles o Geometry of beam on sphere Solar radiation more concentrated near the equator o Atmosphere contributes more at poles deflects more particles back to space Daily temperature cycle o Colder at night warmer during the day o Caused by Earth s rotation Seasonal temperature cycle o June solstice North pole has 24hrs daylight South pole has 24hrs darkness o December solstice daylight North pole has 24hrs darkness South pole has 24hrs o Caused by tilt of Earth s axis relative to the plane of orbit around the sun 23 5 degree tilt Continental Climates o Inland areas more variable in temperature tan coastal areas o Cause land heats and cools faster than water water has a high specific heat b Effects of temperature Lethal temperature o Critical minima and maxima o EX cactus in low temps Suboptimal temperatures o Not lethal but prevents reproduction c Metablolic considerations Endothermy ability to produce substantial amounts of metabolic heat EX mammals birds Ectothermy cannot produce lots of metabolic heat Homeothermy metabolic ability to control body temperature Poikilothermy inability to control body temperature metabolically Endothermic homeotherm makes heat and regulates body temp Heterothermy intermediate metabolisms EX tuna migrates during annual cycle when migration starts body temp is higher than water temp endothermic poikilotherm when not migrating body temp lower than water temp endothermic homeotherm Q10 factor by which reaction rates change per 10 degrees C in temperature o At critical max lethality due to protein denaturation homeostasis of integrated reactions lost d Temperature and development Developmental time degrees x days o Time for development expressed with relation to temperature o Equation developmental time deg x days X avg ambient temp C threshold for development C o EX let developmental time 60 let threshold temp 5 At 10 deg C adulthood takes 12 days At 15 deg C adulthood takes 6 days At higher ambient temps development takes less o Apply to famer with pest in crops Needs to have pesticide when needed don t buy ahead to save money Can predict developmental time to predict outbreak days of pest e Temperature limitation To demonstrate Examples o Determine the most sensitive phrase to temperature of life cycle extension of Shelford s law o Determine range of tolerances during this phase critical maxima and critical minima o Correlate microclimate tolerance and distribution data o Establish cause and effect by experimental manipulation o Eastern phoebe fly catching plant Minimum Jan temp 4C Insect eaters may not be food in north during winter o Wild madder Average Jan temp 4C isotherm Extends north of isotherm but cannot breed here temp is not lethal but suboptimal f Interaction with other factors Example back capped Chickadee o Occurs up into Canada in coniferous forests o Doesn t extend into northern Canada o During winter spend time in roost hills then come out and feed all day Some died of hypothermia by morning If temps were warmer day length were longer or greater food supply the species could extend further north Implications under global warming g Example American Beech o Warm temps control southern limit cold temps control o Would need to migrate north 500 miles to survive under northern limit rapid global warming Does not have the dispersal ability for this Would be more likely to become extinct Dispersal distance about 1 km 10 years 2 Moisture a As a condition b As a resource c Global pattern EX most aquatic organisms EX terrestrial plants soil moisture Annual precipitation o Highest at the equator Subtropical subsidence Warm air rises and cools as it gets higher condenses then rains o Lowest at subtropical deserts and the polar deserts Cold dry air warms as it gets closer to Earth o Hadley cells one in North hemisphere and one in South hemisphere subtropical subsidence o Deserts are about 30 degrees north or south of the equator o Cloud cover lower in deserts o Tropic of Cancer 23 5 deg N o Tropic of Capricorn 23 5 deg S o June solstice N wet season S dry season o December solstice N dry season S wet season d Skip e Temperature moisture interactions EX loblolly pine and winter drought o Has root system and needles o Stomata must be open to photosynthesize o Water gets so cold root system stops working o Loses water by evapotranspiration Under water stress i Loses water through stomata can t gain water from roots Illustrates temperature dependent interactions 3 Additional factors a See lecture outline