5: Organisms and their environment (Part 2)

Terrestrial Environments

Water and soil properties

  • Water is key for life

  • Soil structure

  • Soil particle size

Example:

  • Vogt et al. (2016). Vulnerability of tropical forest ecosystems and forest dependent communities to droughts. Environmental Research 144: 27-38.

Net production is plant biomass growth: leaves, flowers, fruits, and seeds.

Plant Adaptations

Transpiration

  • Transpiration: moving water from the soil to the leaves

    • they must release water in order to move water from the roots (lose to gain)

  • Cohesion-tension theory

Example

A note on data presentation:

Photosynthetic Pathways

  • Adaptation to different environments

    • C3

      • least specialized

      • stomata open during the day

      • wet environments

    • C4

      • important for water-limited environments, in between dry and wet (more dry)

    • CAM plants

      • most specialized

      • example: desert plants, like cacti

      • open stomata at night when they lose less water

        • Crassulacean acid metabolism

Structural adaptations

  • smaller leaves dissipate heat

  • stomata being protected to prevent water loss

  • these adaptations deal with heat and water

Animal adaptations

Water, salt, nitrogen balance

  • Homeostasis

  • Negative feedbacks

  • Nitrogen

    • Ammonia

    • Urea: useful in limited water environments

    • Uric acid: useful if you have enough water

Temperature

  • Body size and thermal inertia

    • Small body-size animals are more vulnerable to losing or gaining heat

    • Large animals have problems losing heat

  • Thermoregulation

Thermal optima

  • the range of temperatures within which organisms perform best

  • Thermoregulation

    • Ectotherms

    • Endotherms

Replication and data variability

Replication: the practice of assigning each treatment to many experimental subjects (the more subjects in each treatment condition, the lower the variability of the dependent measures)

Adaptations to the Environment

Summary

  • Adaptations to the terrestrial environments

    • Importance

    • Variability in time and space