Adaptations and Diversity: Adaptations to Cold Environments

VCE Biology Units 1&2 – Unit 2 AOS 2: How Do Inherited Adaptations Impact on Diversity?

This lesson focuses on adaptations that enhance an organism's survival and enable life to exist in a wide range of environments, specifically concentrating on cold environments.

Adaptations to Cold Environments

Animal Adaptations to Cold

Animals living in cold environments exhibit specific structural, physiological, and behavioural adaptations to minimize heat loss and maintain a stable internal temperature. These adaptations were previously covered in detail in Lesson 7 of Unit 1 AOS 2.

• Endothermy:

  • Definition: The physiological process of generating large amounts of heat within the body to maintain an internal temperature that is metabolically favourable.

• Common Adaptations:

  • Large Size: Larger body size reduces the surface area to volume ratio \left(\frac{SA}{V}\right), which minimizes the relative surface area exposed to the cold and thus reduces heat loss.

  • Rounded Shape: Similar to large size, a more compact, rounded body shape further decreases the surface area to volume ratio \left(\frac{SA}{V}\right), contributing to reduced heat loss.

  • Thick, Insulating Layer: Animals often possess a thick layer of insulation, such as fur, feathers, blubber, or adipose tissue. This layer traps air or provides a dense barrier that slows down the transfer of heat from the body to the environment.

  • Counter-Current Arrangement of Blood Vessels in Extremities: This physiological adaptation involves the positioning of arteries carrying warm blood to the extremities (e.g., feet, flippers) directly alongside veins carrying cooler blood back to the body core.

    • As warm arterial blood flows past the cooler venous blood, heat is transferred from the artery to the vein.

    • This pre-warms the blood returning to the body core, preventing significant heat loss from the core and allowing extremities to operate at a lower temperature without causing overall body hypothermia.

• Examples: Gentoo penguin (Pygoscelis\ papua) and Walrus (Odobenus\ rosmaris).

Plant Adaptations to Cold

Plants in cold environments also possess a variety of adaptations to cope with low temperatures, short growing seasons, and often frozen water availability.

• Low-Growing Form: Plants often grow close to the ground.

  • Benefit: This helps them stay beneath insulating snow cover, avoid strong cold winds, and take advantage of any warmth radiated from the ground.

• Rapid Growth and Seed Production during Warm Weather: In environments with very short summers, plants rapidly complete their life cycle during brief warm periods.

  • Benefit: This ensures reproduction and seed dispersal before the onset of the next cold season, allowing the species to persist.

• Deciduous:

  • Definition: Of a plant, losing its leaves in winter.

  • Benefit: Shedding leaves helps plants conserve water when the ground is frozen and water uptake is difficult, and prevents structural damage to leaves from frost and ice.

• Fuzzy/Waxy Coating:

  • Fuzzy Coating (Hairs/Trichomes): Traps a layer of still air close to the plant's surface, acting as insulation to reduce heat loss.

  • Waxy Coating (Cuticle): Reduces water loss through transpiration, which is crucial when water is unavailable due to freezing.

• Perennial:

  • Definition: Of a plant, living for longer than a year.

  • Benefit: Allows plants to survive harsh cold periods (often underground as bulbs, roots, or rhizomes) and then rapidly resume growth and reproduction when conditions become favorable again, without expending energy on establishing from seed each year.

• Heliotropic:

  • Definition: Of flowers, turning to follow the passage of the sun across the sky.

  • Benefit: Maximizes the absorption of solar radiation, warming the flower. This can accelerate seed development and attract pollinators by creating a warmer microclimate within the flower.

• Example: Arctic daisy (Arctanthemum\ arcticum).

Multiple Choice Activity Review

Question 1: Which of the following is not an animal adaptation to a cold environment?

• A. Small size

• B. Thick layer of insulation

• C. Rounded shape

• D. Arteries to the feet positioned alongside veins

Correct Answer: A. Small size

• Explanation: Animals in cold environments tend to be large, not small, as a larger size reduces the surface area to volume ratio, which minimizes heat loss. Small animals have a higher surface area to volume ratio and would lose heat more rapidly.

Question 2: Many plants that live in cold environments are perennial. This can be seen as an adaptation to cold environments because:

• A. it makes them larger, and therefore increases their surface area to volume ratio.

• B. they avoid losing nutrients in leaves that are killed by frost.

• C. when there is warmer weather they can rapidly start reproducing.

• D. they are protected from cold wind by the hairs on their leaves.

Correct Answer: C. when there is warmer weather they can rapidly start reproducing.

• Explanation: Being perennial allows plants to survive the winter (often via underground structures) and then quickly grow and reproduce during the short, warmer periods, making the most of the limited favorable conditions without needing to establish entirely new roots and shoots from a seed each year.

Linking Concepts

This lesson on adaptations to cold environments is part of a broader study examining how various adaptations (structural, physiological, and behavioural) enable plants and animals to survive in diverse environments. Cold is the second type of environment addressed, with future lessons exploring adaptations to hypertonic or hypotonic environments.