Ecology Study Guide - Exam 1

Genetic Drift

A change in allele frequency as a result of random change.

Describe how a common garden experiment could help you distinguish between genetic differentiation and phenotypic plasticity.

A common garden experiment puts individuals from different populations in the same environment to see if phenotypic differences arise.

Root-to-Shoot Ratio

A comparison of biomass of a plants roots to its leaves and stems.

Hypolimnion

A deeper layer of cold, dense water

Negative Feedback Loop

A deviation in the controlled quantity is counterbalanced by the control system.

Positive Feedback Loop

A deviation in the controlled quantity is further amplified by the control system.

Biome

A distinct biological community that has formed in response to a shared physical climate

Genotype

A genetic constitution of an organism.

Population

A group of individuals living in a specific area at a specific time

Ecosystem

A group of interacting organisms and their physical environment

Community

A group of species that occupy a given are interacting directly/indirectly with one another

Individual

A living being, a single specimen

Locus

A particular location on a a chromosome that is occupied by a particular gene.

Give an example of behavioral, morphological, and physiological phenotypic plasticity.

Behavioral - Frog eggs hatch when embryos sense predators Morphological - Tadpoles raised in the presence of beetle larvae have deep tails Physiological - Tadpoles metamorphose more quickly from a drying pond

What are the different layers of soil?

O : organic matter A : topsoil B : subsoil C : parent rock

Explain how feedback loops allow animals to deal with environmental variability.

Our body temperature is controlled by a negative feedback loop.

How and why does oxygen vary with water depth? How does this change seasonally?

Oxygen varies with water depth due to diffusion. Colder water increases oxygen solubility, until the formation of ice.

Soil Structure

Particle to soil volume

Chemical Weathering

Particles are chemically altered and broken down through chemical reactions - oxidation, hydrolysis, reduction

Qualitative Trait

Phenotypic characteristics that fall into a limited number of discrete categories.

Explain the processes of photosynthesis and cellular respiration.

Photosynthesis is the process of converting CO2 and water into simple sugars. Cellular respiration is the process of converting simple sugars (glucose) and oxygen into energy.

Abiotic

Physical, not derived from living organisms

Explain how plants can alter their structure to handle low water availability.

Plants can change the location of their photosynthetic processes to handle low water availability. They can also time their processes with temporal cycles.

Explain why plants have a temperature optimum. Characterize leaf shape as an adaptation to temperature.

Plants increase their rate of photosynthesis as temperature increases. However, there is a limit to heat in which the reverse effect occurs. Thin and spaced out leaves are typically found in warmer environments while thicker, dense leaves are found in colder environments.

Characterize leaf retention and carnivory as adaptations to low nutrient availability.

Plants may resort to storing water in their leaves or can ivory as an adaption to low nutrient availability.

Explain how poikilotherms and homeotherms regulate their temperature via adaptation and acclimation. What are the advantages and disadvantages of each strategy?

Poikilotherms regulate body temperature primarily through behavioral mechanisms. Homeotherms regulate body temperature through metabolic processes and behavioral mechanisms. Poikilotherms are less energetically expensive but have a narrow range of acceptable environmental conditions. Homeotherms remain active in a variety of conditions but are more energetically expensive.

Stomata

Pores in the epidermis that allow gas exchange.

Distinguish between positive and negative assortative mating. Which type of non-randommating might lead to inbreeding depression?

Positive AM is when mates are chosen based on similar phenotypic traits. Negative AM is when mates are chosen on less similar phenotypic traits Positive AM might lead to inbreeding depression.

How and why does precipitation vary over space and time?

Precipitation is highest near the equator and decreases towards the poles. Air temperature plays a crucial role in the exchange of water between the atmosphere and Earth's surface.

Soil Texture

Proportion of different sized soil particles

Common Garden Experiment

Puts individuals from different populations in the same environment and see if you get phenotypic differences

Explain the existence of alleles that are deleterious in homozygous recessive individual.

Recessive deleterious alleles are "hidden" from natural selection by their dominant non-deleterious counterparts. An individual carrying a single recessive deleterious allele will be healthy and can easily pass the deleterious allele into the next generation.

How and why does light vary with water depth?

Red light is filtered out at shallow depths. Blue light penetrates the deepest. Due to wavelength.

Genetic Bottleneck

Reduced genetic diversity that results from a sharp reduction in the size of the population.

Shade Tolerance

The ability of a plant to maintain a positive carbon balance in low light conditions. Plants with shade tolerance have a high LSP and a low LCP.

Buoyancy

The ability to float in water

Gene Pool

The alleles from all the genes of every individual in a population.

Describe the anatomy of a leaf.

The anatomy of a leaf consists of two main sections, the mesophyll and the epidermis. A third component, the vascular bundle, is used as the transport system. The mesophyll is the tissue layer of the leaf where photosynthesis occurs. Chloroplasts conduct photosynthesis and contain light absorbing pigments called chlorophyll. The epidermis is the outer layer of cells on a leaf. The stomata contains pores in the epidermis that allow gas exchange. Water is also transpired through the stomata.

Allen's Rule

The appendages of animals are smaller relative to body size in colder climates and vice versa.

How do air temperature and movement influence global ocean current?

The atmosphere transports heat through a complex, worldwide pattern of winds; blowing across the sea surface, these winds drive corresponding patterns of ocean currents. But the ocean currents move more slowly than the winds, and have much higher heat storage capacity.

Surface tension

The attractive force exerted upon the surface molecules of a liquid by the molecules beneath that tends to draw the surface molecules into the bulk of the liquid and makes the liquid assume the shape having the least surface area.

Cellular Respiration

The breakdown of carbohydrates (glucose) to harvest energy.

Microclimate

The climate of a very small/restricted area, especially when it differs from the climate of the surrounding area.

Weather

The combination of temperature, humidity, precipitation, wind, clouds, occurring at a specific place and time.

Net Photosynthesis

The difference between the uptake of carbon in photosynthesis and the loss of carbon through respiration.

Explain the ecological niche concept and how it incorporates concepts from throughout this unit: physical world, evolution, adaptations.

The ecological niche concept is the specific set of environmental conditions in which an organism can live and reproduce. A species' ecological niche is an n-dimensional hyper volume where n indicates the number of dimensions (or environmental conditions) that determine where an organism can survive.

Coriolis effect

The effect of Earth's rotation on the direction of winds and currents. A mass moving in a rotating system experiences a force acting perpendicular to the direction of motion and to the axis of rotation.

Diffusion

The general tendency of molecules to move from a region of high concentration to one of lower concentration.

Soil

The layer of chemically and biologically altered material that overlies bedrock other unaltered material at Earth's surface

Light Saturation Point

The level of light at which net photosynthesis reaches the maximum potential.

Chlorophyll

The light absorbing pigment in chloroplasts.

Climate

The long term average pattern of weather

Parent Material

The material from which soil develops; bedrock

Field Capacity

The maximum amount of water held by soil particles against the force of gravity

Ion Exchange Capacity

The number of negatively or positively charged sites on soil particles within a volume of soil

Epidermis

The outer layer of cells on a leaf.

Countercurrent Heat Exchange

The physical arrangement of arteries and veins to allow the transfer of heat. To stay warm or to stay cool.

Phenotype

The physical expression of the genotype, how it looks.

What are the physical properties of soil? How do saturation, field capacity, and wilting point ofour sandy soils compare to those of different soil types

The physical properties of soil are color, texture, structure, moisture, and depth. Sandy soils have are easily saturated and have a low wilting point and field capacity. Loamy soils are moderate throughout. Silty soils are not easily saturated and have a high wilting point and field capacity.

Feedback

The property of a control system to use its output as a part of its input.

Viscosity

The property of a material that measures the force necessary to separate the molecules and allow an object to pass through

Fitness

The proportionate contribution that an individual makes to future generations.

Water Use Efficiency

The ratio of carbon stored (after respiration) per unit of water lost (through transpiration).

Ecology

The scientific relationships between organisms and their environment

Ecological Niche

The specific set of environmental conditions in which an organism can live and reproduce.

Allometry

The study of the relationship of body size to shape, anatomy, physiology.

Subspecies

populations of a species that are distinguishable by one or more characteristics, very little or no gene flow

Sexual Selection

bias toward certain member of the opposite sex based on specific phenotypic traits

Developmental Plasticity

changes in resource allocation during an organisms growth are permanent

Intrasexual Selection

competition between members of the same sex for mating opportunities

Genetic Differentiation

genetic variation between subpopulations (local populations of interbreeding individuals, geographically separated from other pops)

Assortative Mating

individuals choose mates non-randomly with respect to their genotype, usually based on phenotypic traits

Intersexual Selection

mate choice. When members of one sex mate preferentially with of the other sex that have larger, more intense, or more exaggerated characters

Inbreeding

mating of individuals in a population that are more closely related than expected by chance

Adaptive Radiation

the process by which one species gives rise to many species, each are adapted to exploit different features of the environment

Speciation

the process by which two species arise from one common ancestral species

Stabilizing Selection

Natural selection that favors intermediate variants by acting against extreme phenotypes.

Founder Effect

A small number of individuals leave a large population to colonize a near area and bring with them only a small amount of genetic variation.

Gene

A stretch of DNA that encodes a biological molecule with a physiological/behavioral function. The basic unit of inheritance

Chromosome

A threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Mesophyll

A tissue layer in a leaf where photosynthesis occurs.

Quantitative Trait

A trait that is continuously distributed.

Diversifying Selection

A type of natural selection in which organisms with phenotypes at both extremes of the phenotypic range are favored by the environment.

Distinguish adaptation from acclimation. Give one example each of a behavioral, morphological,and physiological adaptation.

Adaptation is a generic phrase encompassing all changes undertaken by an organism to reduce the negative effects of unfamiliar and undesirable external environment. Acclimation differs from acclimatization in that rather than adaptive characteristics being augmented in a natural climate or environment, the stimuli for adaptation is artificially induced, typically within an enclosed chamber within which ambient conditions (temperature/oxygen content) are altered.

Recessive Allele

An allele that is masked when a dominant allele is present. Masked in the heterozygote.

Dominant Allele

An allele whose trait always shows up in the organism when the allele is present. Expressed in the heterozygote.

Distinguish between ecotype and subspecies.

An ecotype is a population adapted to its unique local environmental conditions, but gene flow occurs between adjacent populations. A subspecies is a population of species that are distinguishable by one or more characteristics, with very little or no gene flow between populations.

Explain the concept of an evolutionary trade-off. How and why do trade-offs lead to adaptive radiation?

An evolutionary trade-off occurs when an increase in fitness due to a change in one trait is countered by a simultaneous decrease in fitness due to change of another trait. Trade-offs are a result of environmental conditions. Adaptive radiation, the process by which one species gives rise to many species, can occur through the trade-off of favorable and non-favorable traits.

Chloroplast

An organelle that conducts photosynthesis in the mesophyll.

Poikilotherm

An organism that has varying internal body temperature.

Heterotherm

An organism that uses body endothermy and ectothermy.

Homeotherm

An organisms that maintains nearly constant internal body temperature.

Adaptation

Any heritable, behavioral, morphological, or physiological trait of an organism that has evolved by natural selection and maintains or increases the fitness of an individual in a particular environment.

Demonstrate the relationship between organism size and surface area:volume ratio. How doesthis constrain body size in homeotherms and poikilotherms

As an organism grows larger, its volume grows faster than its surface area. Therefore, its surface area to volume ratio decreases. Poikilotherms are relatively smaller than homeotherms.

Distinguish between biotic and abiotic influences

Biotic influences are all living things. Abiotic influences are not derived from living organisms, they are physical.

Regulator

Uses a variety of physiological, morphological, and behavioral mechanisms to regulate their internal environment over a broad range of external environmental conditions.

Compare and contrast the C3, C4, and CAM pathways in plants. What is the main advantage and disadvantage of each pathway? When/where does each kind of plant perform the Calvin cycle.

C3 plants make up 85% of plants. They intake CO2 through the C3 pathway for the Calvin Cycle. This occurs in the mesophyll. C4 plants are adapted to low water availability. The steps are spatially separated. The C4 pathway is found in the mesophyll while the Calvin Cycle is within a bundle health. These plants expend more energy but lose less water in the process. CAM plants are adapted to very low water availability. The steps are temporally separated. The C4 pathway occurs at night while the Calvin Cycle occurs during the day. Both occur in the mesophyll. This process is very time consuming, resulting in slower plant growth.

Macronutrients

Carbohydrates, proteins, and fats needed in large quantities.

Mechanical Weathering

Caused by physical forces: water, wind, temperature

Marcoevolution

Change above the level of species, takes a significantly longer time.

Microevolution

Change within a species, typically over short time scales.

Conformer

Changes in environmental conditions induce internal changes in the body that parallel the external conditions.

Evolution

Changes in genetic composition of a population over time.

Explain how climate influences biome.

Climate determines the biome based on its typical weather patterns.

Environmentalism

Concern about and action aimed at protecting the environment

Distinguish between conformers and regulators.

Conformers parallel changes in their body to changing environmental conditions. Regulators use physiological, behavioral, and morphological mechanisms to regulate their internal environment over a broad range of environmental conditions.

Photosynthesis

Converts CO2 and water into simple sugars.

Allele

Variant of a gene.

What were the contributions of Cuvier, Lamark, Darwin, and Mendel to evolutionary theory.

Cuvier - extinction and catastrophism Lamark - transmutation and inheritance of acquired characters Darwin - natural selection, common descent Mendel- mechanism of inheritance

Biotic

Derived from living organisms

Natural Selection

Differential survival and/or reproduction of individuals, caused by interactions of the individual and its environment. Reduces genetic diversity.

Distinguish between ecology and environmentalism

Ecology is a science regarding the relationships between organisms and their environment. Environmentalism is the philosophical concern for the environment.

Transpiration

Evaporation of water from plants through the stomata.

How and why does solar radiation vary over space and time

For space, net surface radiation decreases from the equator to the poles. This is due to the length the light must travel and its corresponding surface area it covers, which changes based on the curvature of Earth. For time, the axial tilt is responsible for the seasons, which is a result of the changing distribution of sunlight.

Directional Selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve.

Mutation

Heritable changes in a gene or chromsome.

Explain how heterotherms use both endo- and ectothermy.

Heterotherms can create their own heat but can also exchange thermal energy with the environment.

How and why does topography influence climate?

Higher elevations experience cooler temperatures, slope orientation affects sunlight exposure and temperature variations, and mountains can alter wind patterns and precipitation.

Trait

How a gene affects an individuals physical/behavioral appearance.

Explain incomplete dominance and distinguish it from complete dominance.

In complete dominance, only one allele in the genotype is seen in the phenotype. In incomplete dominance, a mixture of the alleles in the genotype is seen in the phenotype.

Explain the Hardy-Weinberg principle, why its assumptions are unrealistic, and why it's useful anyway.

In the absence of the following conditions, the frequency of genotypes in a population remains constant from generation to generation. Unrealistic due to constant mutation, gene flow, small populations, nonrandom mating, and environmental change. It is useful to estimate the number of homozygous and heterozygous variant carriers based on its allele frequency in populations that are not evolving.

Explain the hierarchical nature of ecology

Individuals are single specimens of the same species that can group together to make a population. Populations of different species that interact with each other form a community. An ecosystem contains the communities and the abiotic (physical) environment that they interact with.

How and why do coastlines influence climate?

Inland areas experience greater seasonal variation in temperature than do coastal areas. This is due to water's high specific heat capacity, which regulates the temperature of the air.

Distinguish between intra- and intersexual selection and give an example of each.

Intrasexual selection is a type of sexual selection in which members of the same sex compete for mating opportunities. Intersexual selection is a type of sexual selection where members of one sex mate preferentially with members of the other sex that have profound characteristics.

What determines soil fertility?

Ion exchange capacity

Thermocline

Layer where temperature changes rapidly

Describe how different factors limit the rate of photosynthesis: light, temperature, water, nutrients.

Light - Plants must reach a light compensation point in order to meet photosynthetic demands. Photosynthetic active radiation (PAR) is the amount of light received. Temperature - Temperature of the leaf (not air) controls the rate of photosynthesis. Photosynthesis increases with an increase in temperature. Temperature will reach a limit in which photosynthesis rate decreases. Water - The rate of photosynthesis depends on the amount of water available. There are multiple ways plants photosynthesis based on water availability. Nutrients - Plants require micro/macronutrients in order to photosynthesize. Plants adapted to low nutrient conditions have long-lived leaves that have a low, steady rate of photosynthesis.

Distinguish between the light-dependent and the light-independent reactions. What are the main reactants and products of each.

Light-dependent reactions use light to create NADPH and ATP which are used in the formation of simple sugars. This process also releases O2. Light-independent reactions use CO2, NADPH, and ATP to form simple sugars. The absence of light requires additional ATP. The process also releases O2

Ectothermy

Maintaining body temperature through exchange of thermal energy with the surrounding environment.

Endothermy

Maintaining body temperature through internally generated metabolic heat.

Homeostasis

Maintenance of a relatively constant internal environment in a varying external environment.

Wilting Point

Moisture level has decreased to a point where plants can no longer extract water

Characterize various morphological adaptations that allow animals to achieve homeostasis in an environment with fluctuating temperatures.

Morphological adaptations that allow animals to achieve homeostasis include shedding, and insulation. (Potentially evaporative cooling)

Gene Flow

Movement of genes between populations.

Characterize shade tolerance as an adaptation.

Shade tolerance is an adaptation for plants in low light conditions. These plants have a higher light saturation point and a lower light compensation point, allowing for the maintenance of positive carbon balance.

How is soil formed? What factors influence this process?

Soil forms from parent material, usually bedrock, combining with biotic factors under suitable climate, topography, and time.

Sympatric Speciation

Speciation between two or more lineages occupying the same physical location. Rare, no physical barrier that is preventing reproductive isolation

Describe the process of speciation and distinguish between allopatric and sympatric speciation.

Speciation is the process by which two species arise from one common ancestral species. Allopatric speciation occurs between two or more spatially disjunct populations. There are physical barriers responsible for the reproductive isolation. Sympatric speciation occurs between two or more lineages that occupy the same physical location. There are no physical barriers.

How and why does temperature vary with water depth? How does this change seasonally?

Temperature varies with depth and is categorized into three layers. The epilimnion (warm, upper), hypolimnion (cold, deep), and thermocline (change). In the winter, the coldest layer in a body of water is the surface. In the spring and fall, the thermocline layer breaks down. IN the summer, the coldest layer is the bottom.

How are terrestrial and aquatic biomes categorized?

Terrestrial biomes are categorized by major plant growth forms. Aquatic biomes are characterized by flow, depth, and salinity.

Convection

The transfer of heat through the circulation of fluids

Vascular Bundle

The transport system in vascular plants.

Light Compensation Point

The value of photosynthetic active radiation of which the uptake of CO2 for photosynthesis equals the loss of CO2 in respiration. The exact value of light to meet energetic needs.

How does sexual selection explain the existence of conspicuous (and often maladaptive) traits such as bright colors, horns, and very long tails? Understand two leading hypotheses to explain why maladaptive traits are sometimes preferred by the choosier sex: runaway sexual selection and the good genes hypothesis?

There are two hypothesis for the existence of conspicuous traits. The first, known as runaway sexual selection, theorizes that a mechanism whereby a secondary sexual trait expressed in one sex becomes genetically correlated with a preference for the trait in the other sex. The second, known as good genes, theorizes that the traits females choose when selecting a mate are honest indicators of the male's ability to pass on genes that will increase the survival or reproductive success of her offspring.

Saturation

There is more water than the pore space can hold

Explain properties of water and why they're important: thermal properties, density, surface tension, viscosity, depth, water movement

Thermal properties: *Solid below 0°C *Liquid between 0-100℃ *Gas above 100℃ Water has a high specific heat capacity and resists changing from one state to another. Density: *Water reaches maximum density at 4℃ Surface Tension: Viscosity: Depth: Light, temperature, and oxygen concentration vary with depth Water Movement: Shapes the environments through upwelling and tidal influence

What problems did aquatic organisms encounter when colonizing land? Given this, why gothere?

Transition from aquatic to terrestrial environments required overcoming seemingly insurmountable obstacles: severe desiccation, large temperature fluctuations, intense solar radiation, and the effects of gravity, all of which rendered the terrestrial environment deadly for most aquatic life forms.

Epilimnion

Upper layer of warm, lighter, less dense water

Micronutrients

Vitamins and minerals needed in small quantities.

How and why do air temperature and movement vary over space and time?

Warm surface air at the equator rises and moves towards the poles. The air at the poles cools and descends to the surface, where it moves back to the equator. Air temperature changes seasonally due to the tilt in Earth's access as well.

How and why does water movement shape the environment? What causes tides?

Water movement shapes the environment through upwelling and tidal influence.

Distinguish between weather and climate

Weather is day-to-day in a smaller area, climate is over a whole region and is the average weather for a long period of time

Bergmann's Rule

Within a broadly distributed clade, species of larger size are found in colder environments and vice versa.

Cline

a gradual phenotypic change over a geographic range

Ecotype

a population adapted to its unique local environmental condition, but gene flow occurs between adjacent populations

Trade-off

an increase in fitness due to a change in one trait is opposed by a decrease in fitness due to a simultaneous change in a second trait

Acclimation

reversible phenotypic changes in an organism in response to changing environmental conditions

Allopatric Speciation

speciation between two or more spatially disjunct populations. Physical barriers that is responsible for reproductive isolation.

Phenotypic Plasticity

the ability of a genotype to give rise to different phenotypic expressions under different environmental conditions