1. Environmental Controls on Life Light Temperature Moisture Picea glauca & 10°C July isotherm

2. Light Heliophytes – –sun loving (shade intolerant) –C 4, CAM Sciophytes – –shade loving (shade tolerant) –C 3

3. Photosynthesis and Light PS increases until maximum, then declines Hyperbolic shape Compensation point Saturation point Photoinhibition

4. Physical Adaptations to High Light Environment Small and thick leaves, Thick cuticle – (covering) Curled, less surface area Reflective surface layer High number of stomata Leaf orientation (heliotropic)

5. Large, soft leaves High amounts of chlorophyll Long-lived leaves Heliotropic leaves! Physical Adaptations to Low Light Environment

6. Life History Adaptations to Light Annuals versus perennials Canopy trees flower more Seeds require light to germinate –Loblolly pine (Pinus taeda)

7. Physiological Adaptations to Light Phenology – timing of changes in growth –Flowering –Leaf shedding –Leaf burst

8. Temperature - Plants Poikilothermic Optimum temperature for photosynthesis - varies EX. Circumarctic treeline –Cold stress, freezing damage

9. Black spruce (Picea glauca) limits and July temps

10. Plant Adaptations to Temperature Dormancy – deciduous How do needleleaved plants survive? Frost hardening –Chemical alteration of liquids (“antifreeze”) –Less water in cells –Cell walls deformed

11. Saguaro –CAM photosynthesis –Palo Verde nurse shrubs Plant Adaptations to Temperature

12. Palm distribution Why can’t palms be cultivated at higher latitudes?

13. Temperature - Animals Poikilotherms –“cold-blooded” -1.9°C body temp OK for Antarctic icefish, 6°C lethal Homeotherms –generate heat through metabolism –37-47°C (10°C higher than core temps.) lethal

14. Northern Limits of the Eastern Pheobe

15. Adaptations to Temperature in Animals Metabolic rates Sweating, panting, licking Ratio of body mass to surface area Behavioral adaptations Shivering Super-cooling (gylcerol) Hybernation Insulation

16. Allen’s Rule Low latitude = high surface area:volume High latitude = low surface area: volume Low latitude = long extremities High latitude = short extremities Latitude and Body Shapes

17. Adaptations to Moisture - Plants Photosynthesis Turgor (rigidity) Movement of nutrients (vascular plants) Xerophytes – dry loving Mesophytes – moist loving Hydrophytes – water loving

18. Transpiration Release of water to atmosphere by plants Generally through stomata Evapotranspiration = transpiration + evaporation

19. Water Stress and Range Moisture deficit = evaporative demand > root absorbtion Creosote (Larrea tridentata) = -2.0- -2.9 Mpa Alder (Alnus spp) = -1 Mpa

20. Lower Treeline High elevations: –Lower evaporative demand –Higher rainfall (orographic) Seedlings have highest sensitivity Fig 3.9

21. Plant Adaptations – Moisture Stress Water stress escapees –Annual plants Water stress avoiders –Cacti –Drought deciduous (Fouquieria splendens –ocotillo) Water stress tolerators –Selaginella lepidophylla “resurrection plants”

22. Cactus Family - avoiders Fine surface root systems Enlarged stems to store water Light colored thorns reflect light CAM ps pathway (stomota open at night) Slow growth rates

23. Moisture - Excess Diffusion of O 2 through water is slow!! Plantanus occidentalis (sycamore) growth declines at >50% soil moisture saturation

24. Moisture - Animals 2/3 water by weight Mammal losses 15-20% water – fatal Water loss lower in arid dwellers Ex. Kangaroo rat (Dipodomys spectabilis) –Dry urine, feces –No sweat –Nocturnal –Water from dry food!

25. Other Physical Factors Chemical nutrients/environment –Nitrate, phosphorous, potassium in plants –Salinity, oxygen for aquatic orgs. Combinations of factors

26. Geographical Range vs. Density Range: Area where species is found Density : Abundance per unit area (rare versus common) Highest densities in range center

27. Gaussian Curve and Environmental Gradients Physiological functioning Density

28. What is a niche? Ecological concept Species exist in a multi-dimensional space defined by various limiting factors that affect physiological functioning and abundance

29. Generalist vs. Specialist Generalist: wide ranges of environmental tolerances Specialist: restricted gradient distributions

30. Correlation Caveat If the geographic range of a species and some climatic variable overlap, does that mean that this variable controls the range of this species? What other factors might affect a species’ range?