Lecture 3-Coping w/ Environmental Variation

Phenotypes

the product of genes interacting with environments

• environmentally induced have a a genetic basis, the environment turns of or off certain genes so different phenotypes develop

reaction norm

the pattern of phenotypic expression of a single genotype across a range of environments.

Phenotypic trade-off

A given phenotype experiences higher fitness in one environment, other phenotypes experience higher fitness in other environments

• how species evolove and adapt

Phenotypic plasticity

The "ability" of a single genotype to produce multiple phenotypes.

• induced by environment

Phenotypic plasticity Factors

• Morphology

• Physiology

• Behavior

• Life history

• Phenology

Morphology

• deals with form and structure

• (e.g., physical defenses, height, size of digestive tract to extract more nutrients).

Physiology

• mechanisms and functions of the body

• (e.g., digestive enzymes, chemical defenses).

Behavior

• organism’s response to stimuli

• (e.g., habitat use, aggressiveness).

Life History

• lifecycle, survival and reproduction events

• (e.g., sexual maturity, clutch size).

Phenology

• timings of seasonal/cyclical biological events

• (e.g., time to start reproduction)

Metabolism

The sum of an organism's biochemical reactions that acquire, use energy and tend to maintain homeostasis

Temperature

Intensity of heat: Average kinetic energy of the molecules in an object or system.

• Animals must regulate their internal temperature (homeostasis)

• °C or °F.

Thermal Neutral Zone

The temperature range over which an endothermic animal at rest can maintain its metabolic rate and temperature without appreciable change.

Critical upper or lower temperatures

Temperatures disrupting metabolic functions and cellular components in the organisms. Important changes can be detected

Radiation

Heat transfer between two objects in the absence of direct contact (no contact).

• sun

Convection

The transfer of heat energy by mass movement of a fluid (gas or liquid).

• cup of water (hot/cold)

Conduction

The transfer of energy (heat) from one place to another directly (by physical contact). Heat flows down a gradient from warmer to cooler areas.

• holding laptop

Evaporation

Loss of water in the form of vapor. Heat is transferred from an organism to its surroundings as water evaporates from the organisms’ surface.

• clouds

Endotherms

Rely primarily on internal heat generation, remain active below freezing temperatures, demand high energy (food) to support metabolism animal

Ectotherms

Regulate body temperature through energy exchange with environment, and tolerate great variation in body temperature

Variation in water availability

An organism’s water balance is determined by energy exchange with the environment

Migration

The seasonal movement of animals from one region to another.

• Temperature

• Darkness

• Food supplies

• Water supplies

• Reproduction

• Predation

Storage of resources

(reserve of energy) in the tissues, roots

Dormancy

Dramatic reduction of the metabolic processes (physiological shutdown):

• Diapause: Insects.

• Hibernation: Mammals

• Torpor: Small birds and mammals

• Aestivation: Snails, desert tortoises, Nile crocodiles