Chapter 3 January 17th

Light Sunlight controls the distribution of plants Amount of sunlight depends on latitude With respect to light, plants classified into 2 categories: Heliophytes Obligate Facultative Sciophytes

Figure 3.2

Morphological Adaptations to Light Succulents Sargassum Sunflower Banana plant (Moorea)

Temperature Transpiration allows plants to be cooler than or warmer than the surrounding air temperature The rate of photosynthesis is dependent upon temperature

Figure 3.3

Figure 3.4

Figure 3.6

Adaptations to heat Features that decrease leaf temperature: Reflective coatings Small hairs Leaves oriented vertically Heliotrophs High transpiration rates Leaf loss Dimorphism

Temperature Cold-blooded animals are pokiliotherms Warm-blooded animals are homeotherms Allen’s Rule – short extremities relative to body mass decreases heat loss Bergmann’s Rule – warm-blooded individuals from cooler climates tend to have larger bodies and smaller surface-to-volume rations, and individuals of the same species from warmer climates

Allen’s Rule/ Bergmann’s Rule

Allen’s Rule/ Bergmann’s Rule

Moisture Required by plants for photosynthesis and temperature control Xerophytes Mesophytes Hydrophytes Transpiration Evapotranspiration

Moisture Three categories of adaptations to dry conditions: Water stress escapees Water stress avoiders Water stress toleraters

Two fundamentals for describing geographic distributions of a species: range and density Geographic range – entire area where a species can be found regardless of whether it is common or rare Density – Difference in abundance of species within its range Carrying capacity – the number of individuals an environment can support per meter or hectare

Carrying Capacity

Ordination Analysis Figure 3.13

Environmental Gradients for Physiological Functioning and Density Zone of optimum – Zone of stress – Zone of intolerance – Zone of tolerance -

Niche – the function of a species in the environment Habitat – explicit spatial environment where a species can be found Generalists – species that can tolerate a wide range of environmental conditions Specialists – species that have narrow environmental tolerances

Limiting Factors