Ecology Exam 1

What is ecology?

The scientific study of interactions among organisms and between organisms and their environment

What types of interactions are central to ecology?

Interactions among organisms and interactions between organisms and biotic and abiotic environmental factors

What is a key question ecologists ask about energy?

How organisms acquire, use, and transfer energy and nutrients

What resources do organisms compete for?

Mates, food, water, light, space, and nutrients

Why do ecologists study population distribution?

To understand how many organisms exist and why they occur where they do

What are biotic factors?

Living components of the environment such as predators, prey, competitors, parasites, and mutualists

What are abiotic factors?

Non-living physical and chemical factors like temperature, water, light, oxygen, and nutrients

What is conservation biology?

A mission-driven, multidisciplinary science focused on protecting biological diversity

Why is conservation biology mission-driven?

Because it aims to solve real-world threats to species and ecosystems

Example of conservation biology influencing policy

The Endangered Species Act

Why are southern sea otters ecologically important?

They are a keystone species that strongly influence kelp forest ecosystems

What problem was observed in sea otter populations?

Populations were not recovering despite long-term legal protection

What disease significantly affected sea otters?

Toxoplasmosis caused by Toxoplasma gondii

What organism causes toxoplasmosis?

The protozoan parasite Toxoplasma gondii

What is the primary land-based source of Toxoplasma?

Domestic cats shedding oocysts in feces

How does Toxoplasma reach marine ecosystems?

Through flushed cat litter, runoff, and sewage entering coastal waters

Why is prey choice important for sea otters?

Different prey species carry different risks of pathogen exposure

What ecological concept does this case illustrate?

Everything in ecosystems is interconnected across land and sea

What methods do ecologists use to study nature?

Observational studies, field experiments, lab experiments, and quantitative models

What is an observational study?

A study that records natural patterns without manipulating variables

What is the purpose of quantitative models?

To predict ecological patterns and test scenarios that are difficult to observe directly

Step 1 of the scientific method

Make observations and ask questions

Step 2 of the scientific method

Develop hypotheses using prior knowledge or intuition

Step 3 of the scientific method

Evaluate hypotheses using experiments, observations, or models

Step 4 of the scientific method

Use results to refine hypotheses, ask new questions, or draw conclusions

What does “everything is connected” mean?

Changes in one part of an ecosystem can affect many other parts

Why is time important in ecology?

Ecosystems change over time and differ between past, present, and future

Why can no population grow indefinitely?

Resources are limited, placing constraints on population size

What is the difference between climate and weather?

Weather is short-term atmospheric conditions; climate is long-term averages and variation measured over decades

Why is climate fundamental to the physical environment?

It shapes ecosystems, species distributions, and long-term environmental patterns

What are the major time scales of climate change?

Daily, seasonal, multi-year, millennial, and geological (millions–billions of years)

How can daily weather affect organisms?

Cold or rainy conditions can reduce activity, such as bats hunting fewer insects

What are examples of seasonal variation?

Winter vs. summer and wet vs. dry seasons

What is the El Niño Southern Oscillation (ENSO)?

A multi-year climate pattern occurring every 3–8 years and lasting ~18 months

What defines El Niño conditions?

Warmer-than-average sea surface temperatures in the Pacific Ocean

How does ENSO affect seabirds?

Warming events can shift nesting ranges northward (e.g., Elegant Terns)

What occurs at the millennial climate scale?

Ice ages, interglacial periods, and biome shifts

What distinguishes ice ages from interglacial periods?

Ice ages are colder with extensive ice cover; interglacials are warmer intervals

What drives climate change over millions of years?

Plate tectonics and continental drift

What is a biome?

A large-scale ecological community defined by temperature and precipitation

What two variables define biomes?

Average annual temperature and precipitation

What are growth forms?

Structural plant adaptations to specific climates

What climate defines tropical rain forests?

Warm temperatures and high rainfall year-round

What characterizes temperate deciduous forests?

Seasonal climate and trees that lose leaves annually

What climate defines chaparral?

Hot, dry summers and mild, wet winters

What are sclerophyllous shrubs adapted for?

Dry conditions and water conservation

What climate defines boreal forests?

Long, cold winters and short growing seasons

What defines desert climates?

Extremely low precipitation

What conditions favor grasslands?

Moderate rainfall, fire, and grazing pressure

What characterizes tundra climates?

Cold temperatures, low precipitation, and permafrost

Why is energy central to ecosystems?

It controls productivity, food webs, and survival

What are autotrophs?

Organisms that convert sunlight or chemical energy into stored chemical energy

What are heterotrophs?

Organisms that obtain energy by consuming organic matter

What are responses to environmental variation?

They are physiological, behavioral, or morphological adjustments organisms make to cope with changing environmental conditions

How does the environment control physiology?

Environmental factors such as temperature, water, light, and nutrients regulate metabolism, growth, and survival

What is physiological stress?

It is a condition in which environmental demands exceed an organism’s ability to maintain homeostasis

What is acclimatization?

It is a reversible physiological adjustment made by an individual in response to environmental change

What are ecotypes?

They are genetically distinct populations adapted to specific local environmental conditions

What are coping mechanisms in ecology?

They are strategies that reduce the negative effects of environmental stress

What is energy in an ecological context?

Energy is the capacity to do work and limits growth, reproduction, and survival

How does variation in temperature affect organisms?

It alters metabolic rates, enzyme activity, and overall physiological performance

How do terrestrial plants exchange energy with their environment?

Through radiation absorption, convection, conduction, and transpiration

What physical modifications affect energy exchange in plants?

Leaf size, shape, orientation, surface color, and reflectivity influence heat gain and loss

How does variation in water availability affect organisms?

It influences water balance, photosynthesis, growth, and survival

Why is variation in solutes important for organisms?

Changes in solute concentrations affect osmotic balance and cellular function

What is the trade-off between photosynthesis and water loss?

Opening stomata allows CO₂ uptake but increases transpiration and water loss

What physical modifications help plants balance water loss?

Waxy cuticles, reduced leaf area, sunken stomata, and deep root systems

How does water balance vary among species?

Species differ in water-use efficiency and tolerance to drought or flooding

How do frozen frogs survive freezing temperatures?

They produce cryoprotectants that prevent ice damage to cells

What is evolution?

Evolution is a change in allele frequencies within a population over generations

What is directional selection?

It favors one extreme phenotype, shifting the population mean

What is disruptive selection?

It favors extreme phenotypes over intermediate ones

What is stabilizing selection?

It favors intermediate phenotypes and reduces variation

What is genetic drift?

It is random change in allele frequencies, strongest in small populations

What is life history?

It is the pattern of growth, reproduction, and survival across an organism’s lifetime

What is semelparity?

It is a life history strategy where an organism reproduces once and then dies

What is iteroparity?

It is a strategy where an organism reproduces multiple times during its life

How does mortality influence semelparity versus iteroparity?

High adult mortality favors semelparity, while low mortality favors iteroparity

What is fecundity?

Fecundity is the number of offspring produced by an organism

What is reproductive effort?

It is the proportion of energy allocated to reproduction instead of growth or maintenance

Why are salmon considered semelparous?

They reproduce once, investing all energy into a single reproductive event

Why are mayflies considered semelparous?

They have a brief adult stage focused entirely on reproduction

Why is bamboo considered semelparous?

It flowers once after many years and then dies

Why are kangaroos considered iteroparous?

They reproduce multiple times and provide extended parental care

Why are dandelions considered iteroparous?

They reproduce repeatedly and produce many small seeds over time

What is the trade-off between offspring number and offspring size?

Producing more offspring reduces resources available per offspring

How does offspring size affect survival?

Larger offspring generally have higher survival rates

What is the trade-off between parental care and no parental care?

Parental care increases offspring survival but reduces future reproduction

What is the trade-off between parental investment and parent survival?

High investment can reduce the parent’s longevity or future reproductive success

How do birds illustrate parental investment trade-offs?

Birds with high parental care produce fewer but larger offspring

How do fir trees show a trade-off between growth and reproduction?

Energy invested in cone production reduces growth and future competitive ability

How do grasses show a trade-off between growth and reproduction?

Early reproduction can limit vegetative growth and long-term survival

What are legacy effects of reproductive timing?

The timing of reproduction affects future growth, survival, and fitness

What characterizes r-selected strategies?

High fecundity, low parental care, short lifespan, and unstable environments

What characterizes K-selected strategies?

Low fecundity, high parental care, long lifespan, and stable environments

What is the CSR triangle in plant ecology?

A framework classifying plants as Competitive (C), Stress-tolerant (S), or Ruderal (R)

What defines a competitive (C) plant strategy?

Maximizing growth and resource acquisition in low-stress environments

How do stress-tolerant (S) and ruderal (R) strategies differ?

Stress-tolerant plants survive harsh conditions, while ruderal plants reproduce rapidly after disturbance