Ecology Exam 1

Ecologists study…?

• Ecologists study environmental relationships from individual organisms to factors that influence global processes.

What makes the transport of water through plants possible

Water cohesion

Physiological ecologists focus on…?

• Physiological ecologists focus on the evolution of physiological and anatomical mechanisms that organisms adapt due to physical and chemical environmental challenges 

Behavior ecologists focus on…?

• Behavior ecologists focus on the evolution of behaviors that allow animals to survive and reproduce 

Population ecology focuses on…?

• Population ecology focuses on factors influencing population structures and processes

Population definition

• Population: Group of interbreeding individuals of a single species in a defined area

Community definition

• Community: Association of interacting species

Ecosystem definition

• Ecosystem: Biological community together with its associated physical and chemical environment

Biosphere definition

• Biosphere: The portions of the Earth that support life, including the land, waters, and atmosphere

What type of ecology is involved with the biosphere

Landscape ecology

What are the three types of research?

Observation, Experimentation, Modeling

What is observational research

• Collection of data in unmanipulated settings

Give examples of observational research

• Counting the number of birds or describing types of fungal spores

• Work takes place either in situ, in the field, or using specimens collected in nature that are then observed in a laboratory. 

• Binoculars, drones with cameras, stable isotope analysis

What is experimentation research

• Experimentation: Research that involves manipulation of variables of interest while holding others constant to test a hypothesis

Where does experimentation research occur?

Occurs in the field or controlled environments like a lab, garden, greenhouse, or outdoor enclosures

What is modeling research?

• Modeling: Creation and analysis of representations of data or ideas to provide insight or make predictions

What are conceptual models?

• Conceptual models: Systems in pictures or diagrams

What are quantitative models?

• Quantitative models: Mathematical and may involve complex equations

What is a phenotype?

Observable characteristic

What is phenotypic plasticity?

• Phenotypic Plasticity: Organisms change the expression of traits in response to the environment

What are ecotypes?

• Ecotypes: Locally adapted and genetically distinctive populations within a species

Discuss the Clausen’s Common Garden Experiment

• Individuals from two or more populations are transplanted and grown in the same environment. Cloning lowland, mid-elevation, and alpine plants and growing them in experimental gardens

• Plant height differed significantly among the study sites. Different plants responded differently to the environments. Mid-elevation and alpine plants attained the greatest height in the mid-elevation garden. Lowland plants grew tallest in the lowland garden

What is the Hardy-Weinberg Principle for?

• Hardy-Weinberg equilibrium: Helps identify evolutionary forces that can change gene frequencies in populations

What are the two equations for the hardy-weinberg pricnple?

• p² + 2pq + q² = 1.0

• p + q = 1.0

What are the conditions for the hardy-weinberg principle?

Conditions: Random mating, no mutations, large population size, no migration, and all genotypes have equal fitness

Fitness definition

• Fitness: Genetic contribution of individuals to future generations

Natural selection definition

• Differential survival and reproduction among phenotypes

• Polygenic traits definition

• Polygenic traits: Characteristics controlled by multiple genes

• Traits may have two possible categories or vary along a gradient

• Like skin color

• Quantitative genetics definition

• Quantitative genetics: Mathematical treatment of continuously varying traits and how they respond to natural selection

• Stabilizing selection definition

• Stabilizing selection: Acts against extreme phenotypes and can act to impede changes in populations

Stabilizing selection characteristics

• Favors average phenotype

• Bell-shaped curve

• Average individuals have higher evolutionary fitness compared to extremes

• Directional Selection defintion

• Directional Selection: Favors extreme phenotype over other phenotypes

• Disruptive Selection definition

• Disruptive Selection: Favors two or more extreme phenotypes over the average phenotype in a population

Heritability definition

• Heritability: The proportion of total phenotypic variation in a trait attributable to genetic variation. It determines the potential for evolutionary change in a trait

What is heritability symbolized as?

• Usually symbolized as h²

Heritability equations:

• h² = V_G / V_P

• h² = V_G / ( V_G + V_E )

• h² = V_G / V_P

• h² = V_G / ( V_G + V_E )

What do the variables stand for?

• h² = Heritability

• V_G = Genetic variance

• V_P = Phenotypic variance

• V_E = Environmental effect

What does the heritability of a particular trait depend on?

• Heritability of a particular trait depends on the relative sizes of genetic versus environmental variance

Describe Stabilizing selection for egg sizes

• Eggs too small or too large lead to lower hatching and reduced lifetime production of offspring

Describe Directional selection for soapberry bugs

• Feeds on seeds using slender beaks.

• The beak length depends on the radius of the fruit. The larger the fruit, the larger the beaks

Describe Disruptive selection of finches

• Favored smaller and larger beak sizes, not medium beak sizes

What can change gene frequencies in populations, especially small populations

Genetic drift

Define Genetic drift

• Genetic Drift: Allele frequencies change over generations due to random chance instead of natural selection

Define founder effect

• Founder effect: Subset of the original population becomes a new population

Define population bottleneck

• Population bottlenecks: Large portions of a population are killed by a chance event unrelated to genotype, leaving behind reduced genetic diversity and/or different frequencies of alleles than existed before

What can population bottlenecks lead to?

• Can lead to increased inbreeding

  • Populations with the highest level of inbreeding have the highest probabilities of extinction

Macroclimate definition

• Macroclimate: Prevailing weather conditions in a region over a long period of time

Microclimate definition

• Microclimate: Climatic variation on a scale of a few kilometers, meters, or even centimeters, usually measured over short periods of time

What are the six (kinda seven) things that affect microclimates?

• Altitude: Temperatures are generally lower at higher elevations

• Aspect: Topographic features such as hills and mountains due to shading some parts and exposing other parts to the sun.

• Vegetation: Shades the landscape, creating microclimates, and plant litter also produces microclimates that decrease temperature

• Color of the Ground: Changes the temperature

• Presence of boulders and burrows: Decreases temperature

• Aquatic temperatures: 

  • Very stable temperature

    • High capacity to absorb heat

    • Large amount of heat absorbed by water as it evaporates

    • Heat energy that water gives up to the environment as it freezes

  • Riparian vegetation: Vegetation that grows along rivers and streams, influences the temperature in streams, decreasing temperature

What is the principle of allocation?

• Principle of allocation: If an organism allocates energy to one function, such as growth or reproduction, it reduces the amount of energy available to other functions, such as defense

What did Bennett and Lenski test with bacterium fitness?

• Bennett and Lenski tested bacterium fitness at 20C and 40C and found that adaptations occurred at 20C with decreased fitness compared to ancestors grown at 40C

What is acclimation?

• Acclimation: Physiological adjustment to a change in a particular environmental factor, such as temperature or salinity

Equation for heat stored in the body of an organism

• H_S = H_m ± H_cd ± H_cv ± H_r - H_e

• H_S = H_m ± H_cd ± H_cv ± H_r - H_e

• What do the variables stand for?

• H_S : The total heat stored in the body of an organism

• H_m : Heat gained from metabolism

  • Metabolic heat is the energy released within an organism during cellular respiration

• H_cd : Heat lost or gained by conduction

  • Conduction is the transfer of heat between objects in direct physical contact

• H_cv : Heat lost or gained by convection

  • Convection is the process of heat flow between a solid body and a moving fluid

• H_r : Heat lost or gained by radiation

  • Radiation is the transfer of heat through electromagnetic radiation,

• H_e : Heat lost by evaporation

Define poikilotherms

Organisms whose body temperature varies directly with environmental temperatures

Define ectotherms

• Ectotherms: Organisms that rely mainly on external sources of energy for regulating body temperature

Define endotherms

• Endotherms: Organisms that rely mainly on internally derived metabolic heat energy

Define homeotherms

• Homeotherms: Endotherms that use metabolic energy to maintain a relatively constant body temperature

Plant heat regulation eqation

• H_S = H_cd ± H_cv ± H_r 

• Metabolism is so small that it is negligible

• To decrease overheating desert plants do what

• Place their foliage far enough above the ground to avoid conductive heating.

• Have small leaves, which give high conductive cooling

• Have reflective surfaces to decrease radiative heat gain

• To conserve heat, arctic/alpine plants do what

• Have dark pigments and orient leaves and flowers perpendicular to sun rays, all of which increase radiative heat gain 

• Have cushion growth, which gains heat from warm substrate through conduction and reduces convective heat loss

What do Tropical Alpine Plants do to maintain temperature?

Retain dead leaves to insulate the stem, conserving heat and reducing convective heat losses

What do lizards do to maintain body temperature? What type of therm is it?

• Ectothermic

• Basks in the sun to warm its body or seeks shade to cool

What do grasshoppers do to maintain body temperature? What type of therm is it?

Ectothermic

Bask in the sun and can adjust capacity for radiative heating. Differing pigmentation between species of grasshoppers

What is the Thermal Neutral Zone? What type of therm animals use it?

Endothermic

The range of environmental temperature over which the metabolic rate of a homeothermic animal does not change

What happens when temperatures are too low and too high outside of the thermal neutral zone?

• When temperatures are outside the zone:

  • Low Temperatures: Shivering, release hormones, etc

  • High Temperatures: heart rate and blood flow to skin increases which increases radiative heat loss

Why are aquatic animals able to be endothermic/homeothermic

• Can be homeothermic in an aquatic environment because:

  • They are all air breathers and do not expose respiratory surface to the surrounding water

  • Well insulated with thick layers of fat. Parts not insulated rely on countercurrent heat exchangers

Describe how plants can be thermogenic

• Use metabolic energy to heat their flowers

• Can change metabolic rate depending on the temperature

How do many organisms survive extreme temperatures?

Entering a resting state

Define animal inactivity

• Seeking shelter during the hottest or coldest times of the day

Describe animals reducing metabolic rate

• Reducing Metabolic Rate: When food is scarce and night temperatures are low, an organism can enter torpor for short-term or hibernation/estivation for long-term

Torpor definition

• Torpor: State of low metabolic rate and lowered body temperature

Hibernation definition

• Hibernation: A dormant state, involving reduced metabolic rate, that occurs in some animals during the winter.

Estivation defintion

• Estivation: A dormant state that some animals enter during the summer; involves a reduction of metabolic rate.

Discuss Hibernation in Tropical Species:

• During the dry season of the tropics, which can last up to eight months, some organisms will hibernate.

What influences the movement of water between an organism and its environment

Concentration graidnets

Relative humidity defintion

• Relative humidity: The percent of water content of air relative to a potential maximum

Relative humidity equation

• RH = Water Vapor Density / Saturation water vapor density * 100%

Water vapor pressure definition

• Water vapor pressure: The atmospheric pressure exerted by the water vapor in the air; increases as the water vapor in the air increases

Saturation water vapor pressure definition

• Saturation water vapor pressure: The pressure exerted by the water vapor in air that is saturated with water vapor

Diffusion definition

• Diffusion: Transport of material due to the random movement of particles; new movement is from areas of high concentration to low concentration

Osmosis definition

• Osmosis: Diffusion of water down its concentration gradient

• Aquatic organisms live in one of three circumstances. Name the three

Isomotic, Hypoosmotic, Hyperosmotic

Hypoosmotic definition

• Hypoosmotic: Organism with body fluids with a higher concentration of water and lower solute concentration than the external environment 

Isomotic defintion

• Isomotic: Organism with body fluids with the same concentration of water and solutes as the external environment

Hyperosmotic defintion

• Hyperosmotic: Organism with body fluids with a lower concentration of water and higher solute concentration than the external environment 

Water potential definition

• Water potential: The capacity of water to do work

How does changing solution concentration change water potential

• Increasing solute concentration decreases water potential 

• Decreasing solute concentration increases water potential 

What is the water potential of pure water?

0

What is the symbol of water potential?

Ψ (psi)

What is Ψ_solutes ?

• Ψ_solutes is the reduction in water potential due to dissolved substances, which is a negative number

Matric forces defintion

• Matric forces: A force resulting from water’s tendency to adhere to the walls of containers such as cell walls

• Ψ_matric

Cohesion defintion

• Cohesion: A property of water whereby molecules stick together, making the transport of water through plants possible

Equation of water potential of plants?

• Ψ_plant = Ψ_solutes + Ψ_matric + Ψ_pressure

How do Ψ_soil and Ψ_matric compare?

• Ψ_soil > Ψ_matric

How do Ψ_plant and Ψ_soil compare?

• Ψ_plant < Ψ_soil

How do terrestrial plants and animals regulate their internal water?

• Terrestrial plants and animals regulate their internal water by balancing water acquisition against water loss

What is the animal water regulation equation?

• W_ia = W_d + W_f + W_a - W_e - W_s

Define variables of the animal water regulation equation

W_ia = W_d + W_f + W_a - W_e - W_s

• W_ia : Internal water of an animal

• W_d : Water taken by drinking

• W_f : Water taken in with food

• W_a : Water absorbed from the air

• W_e : Water lost by evaporation

• W_s : Water lost with secretion/excretion

What is the plant water regulation equation?

• W_ip = W_r + W_a - W_t - W_s