8Latitudinal 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
13Sweden 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
22Kangaroos/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.
23Figure 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.