4: Organisms and their adaptations to the environment

Adaptations to the Environment

Goals

  • Understand environmental controls on organisms

  • Obtain a general appreciation for adaptations

  • Discuss applications: invasive species, environmental assessment

Reading Guide

  • Chapter 3: The challenges of living in Aquatic Environments

  • Chapter 4: The challenges of living in Terrestrial Environments

Importance

The environment sets the stage, organisms have to adapt or move to other locations.

Understanding responses to the environment allows us to:

  • Understand adaptations

  • Determine habitat use

  • Draw species distributions

  • Manage invasive species

an example: red devils

Key adaptations

  • Low flow

  • High solutes

  • Reproduces in cavities, under rocks

  • Bottom feeder, omnivorous

Understanding the how organisms respond and adapt to their environments help us understand their current distribution and response to change.

Aquatic environments

Water properties

  • Water is key for life.

  • Thermal properties

  • Density

  • Viscosity

  • Solvent

  • Hydrogen and pH

Osmoregulation: Freshwater

  • Hyperosmotic

    • High solutes in tissue than in water

Osmoregulation: Saltwater

  • Hyposmotic

    • High solutes in water

Aquatic Environments

Saltwater

Food - Proteins - Nitrogen

  • Ammonia

    • simple way to excrete excess N

    • toxic

  • Urea

    • more complex

    • saves water

  • Urea as adaptation

    • sharks and rays

    • balance salts in body vs environment

    • require further adaptations

      • trimethylamine

Saltwater - energy cost

  • landlocked lakes

    • hypersaline

Osmotic balance

  • road salt impacts

Gas exchange

  • carbon dioxide

    • not as abundant in water

    • CO2 and HCO3- stable molecules

    • CO2 abundant in low pH environments

  • moves slowly in water

  • CO2 smaller than HCO3-

  • Boundary layer

Gases

Oxygen exchange

  • not as abundant in water

  • concurrent vs countercurrent circulation

Water pH

CO_2 - H2O balance

pH = -log (H+ concentration)

Episodic acidification

  • La Selva biological Station, Costa Rica

  • Aquatic organisms appear to be well - adapted to episodic events

  • Vulnerable only to extreme declines in pH

  • There is an energy cost!

Adaptations to the Environment

Summary

  • Adaptations to aquatic environments

    • Importance

    • Ion balance

    • Gas exchange

    • pH