8 Latitudinal variation in sunlight intensity Figure 52.3aAtmosphere90°N (North Pole)60°NLow angle of incoming sunlight30°N23.5°N (Tropic ofCancerSun overhead at equinoxes0° (Equator)23.5°S (Tropic ofCapricorn)30°SFigure 52.3 Exploring: Global Climate PatternsLow angle of incoming sunlight60°S90°S (South Pole)Latitudinal variation in sunlight intensity
12 (a) 4.5°C warming over next century (b) 6.5°C warming over next Figure 52.7CurrentrangePredictedrangeFigure 52.7 Current range and predicted range for the American beech under two climate-change scenarios.Overlap(a) 4.5°C warming over nextcentury(b) 6.5°C warming over nextcentury
13 Sweden Finland Expanded range in 1997 Range in 1970 Figure 52.8 Figure 52.8 Northward range expansion of the silver-washed fritillary in Sweden and Finland.Expanded range in 1997Range in 1970
22 Kangaroos/km2 0–0.1 0.1–1 1–5 5–10 10–20 > 20 Limits of Figure 52.17Kangaroos/km20–0.10.1–11–55–1010–20> 20Limits ofdistributionFigure Distribution and abundance of the red kangaroo in Australia, based on aerial surveys.
23 Figure 52.18Why is speciesX absentfrom an area?YesArea inaccessibleor insufficient timeYesPredation,parasitism,competition,diseaseDoes dispersallimit itsdistribution?Habitat selectionYesDoes behaviorlimit itsdistribution?NoDo biotic factors(other species)limit itsdistribution?NoDo abioticfactors limit itsdistribution?NoPhysicalfactorsChemicalfactorsFigure Flowchart of factors limiting geographic distribution.Ecologists ask questions about where species occur and why species occur where they doTemperatureLightSoil structureFireMoisture, etc.WaterOxygenSalinitypHSoil nutrients,etc.
30 August 1982 February 1983 August 1983 February 1984 Figure 52.20RESULTS100Both limpets and urchinsremoved80Sea urchinOnly urchinsremoved60Seaweed cover (%)Limpet40Figure Inquiry: Does feeding by sea urchins limit seaweed distribution?Only limpets removed20Control (both urchinsand limpets present)August1982February1983August1983February1984