Ecology - Exam 1

What is the definition of Ecology? (chapter 1)

The branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

How does ecology differ from environmentalism?

Ecology is a science studying organism-environment interactions, while environmentalism is a political movement advocating for environmental protection

A more complete definition of ecology?

The study of how organisms interact with each other and the physical environment, and how these interactions determine species distributions and abundances.

Examples of physical factors influencing ecology?

Soil nutrients, light, moisture, temperature.

Examples of biological factors influencing ecology?

Competitors, seed dispersers, herbivores, decomposers, pathogens.

What are the hierarchical levels of ecological organization?

Individual → Population → Community → Ecosystem → Landscape → Biosphere.

Define population in ecology.

Many individuals of a same species that can reproduce

Define community in ecology.

Many individuals of different/multiple species

Define ecosystem.

All organisms in an area + interaction w/ abiotic factors

What determines the type of ecology studied?

The spatial scale of the question (population, community, ecosystem, global).

What are major subfields of ecology?

Theoretical, evolutionary, disease, animal, plant, applied, behavioral, molecular, conservation, landscape, global change, physiological, human, invasion ecology.

What are the steps of the scientific method in ecology?

Observation → Question → Hypothesis → Prediction → Test (experiment or observation).

Difference between observational vs. experimental study?

• Observational looks for natural patterns

  • Field experiment = natural setting (realistic, less controlled).

• Experimental manipulates factors.

  • Lab experiment = controlled, less realistic.

What is the role of statistics in ecology?

To analyze data and test hypotheses about ecological interactions.

What is genetic variation? (Chapter 5)

Differences in nucleotide sequences of genes at the same locus between/within individuals.

Define allele.

Different versions of the same gene.

What is this kind of allelic variation called?

Homozygote

What is this kind of allelic variation called?

Heterozygote

Define genotype vs phenotype.

• Genotype = genetic makeup

• Phenotype = observable traits.

What do you call an allele that completely overshadows another?

What do you call an allele that is completely overshadowed?

• Complete dominant

• Recessive

What is phenotypic plasticity? How many types are there?

• Ability of the same genotype to produce different phenotypes in different environments. (diff phenotypes for diff environments)

• 2 types (developmental plasticity and acclimation)

What is developmental plasticity?

Irreversible, shaped during development

What is acclimation?

Reversible, often physiological/behavioral

What kind of phenotypic plasticity is this?

Developmental Plasticity

(Another example)

What kind of phenotypic plasticity is this?

Acclimation

What maintains genetic variation in populations?

Sexual reproduction.

What is the Hardy-Weinberg principle?

Populations DONT evolve if…

• mating is random

• no mutations

• large population

• no migration

• no natural selection

What are the main mechanisms of evolution? (ways evolution happens)

• Natural selection

• mutation

• migration (gene flow)

How do we measure whether populations change through time? (Quantifying genetic variation)

• Given number / total number

• same thing with calculating population variation (ex. # brown beetles / total # beetles

What is a Selection Agent?

doing the action selection (could be rain, animals, other stuff, it's just what's causing the change)

(Predators, competition, environment)

Do individuals evolve?

NO, individuals dont evolve, POPULATIONS do!!!

What does natural selection act on?

Phenotype, not genotype

(selection agent has no idea what the genotype its)

Why must Phenotypes differ for populations to evolve?

• Need to have variation among individuals, some more likely to survive — other not

What does it mean when something is selected for?

Higher survivorship

What does it mean when something is selected against?

Lower survivorship

What are the outcomes of Natural selections

• populations evolve

• Leads to adaption

In order for Natural Selection to lead to —> Adaption…

• Traits must be heritable + Beneficial (increase fitness)

What is fitness

• Probability of contributing alleles to the next generation.

• How likely is an organism gonna have babies and pass down its alleles

Is Natural Selection random? Is mutation random?

• No its not random

• Yes it is random

What are the 3 types of natural selection?

• Stabilizing (favors average, middle)

• Directional (favors one extreme)

• Diversifying/Disruptive (favors both extremes)

What type of Natural Selection is this? What does it show?

• Stabilizing Selection

• The extreme phenotypes are selected against, and the common/average/middle is selected for

• ex.

What type of Natural Selection is this? What does it show?

• Directional Selection

• One extreme phenotype is selected for

• ex.

  

What type of Natural Selection is this? What does it show?

• Diversifying Selection

• Both the Extremes are selected for while the intermediate/middle is selected against

• ex.

  

COVID and Delta variant Example…

1. COVID mutated into Delta

2. Migrated to US

3. Adapted to become resistant to medicine and to become for contagious

Define Cline and give example

A Gradual change in phenotypical traits cross geographical space

ex. Body size in moose get larger as you go further North

Define Ecotype and give example.

• Abrupt changes in trait caused by adaptions to local environment

• Ex.

Define Local adaptation

• When a population is better suited to its local environment, than others of the same species elsewhere

What is Genetic Drift? Does it happen in small or large pops? is it random?

• Mechanism for evolution

• occurs in small populations

• Yes its random

• 

What abiotic resources do plants require? Chapter 6)

Light, nutrients (N, P, etc.), water, temperature.

What is an environmental gradient?

A change in availability/quality of abiotic resources over space or time.

What is photosynthesis?

• Conversion of CO₂ + H₂O into sugars using light energy (produces oxygen as byproduct).

• Takes up a lot of energy bc of chloroplast

Why don’t all plant cells have chloroplasts?

Chloroplasts are costly to build (require nitrogen); plants must also allocate energy to structure, respiration, roots.

If photosynthesis is so important, why don’t plants just produce all cells with chloroplasts?

1. The structure (chloroplast) and enzyme for

reaction (rubisco) are energetically costly

to produce and require lots of resources

(e.g. nitrogen)

2. Plants that are undergoing photosynthesis

lose a lot of water through transpiration

What is transpiration?

Water loss from plants during photosynthesis, mainly through stomata.

What is stomata?

Leaf pores that regulate gas exchange and water loss.

Plant adaptations to dry environments?

• Efficient stomatal timing (closes in the day, open at night)

• Fewer stomata per leaf

• Deep roots

• Thicker leaves (reduces surface area ration on leaf)

• Slower growth. (less growth = less photo = less water loss)

Plant adaptations to nutrient-poor environments?

• Large root systems (root hairs)

• Mutualistic relationship with other organisms (Mutualisms with mycorrhizal fungi)

• Long-lived leaves

  

• Plant adaptations to differing light levels?

• Shade tolerance meaning?

Shade tolerance = Ability of a plant to tolerate low light

Shade Tolerant Plants…

• lower Photosynthesis rates

• Slower growth

• more defense (these survive more bc better defense)

• Invest more into root, less in leaves

Shade Intolerant Plants…

• Higher Photosynthesis rates

• faster growth

• less defense

• Invest more on leaves, less on roots

Why don’t plants always grow in better conditions than they were in before?

A species adapted to low amounts of resources does not do well when those resources become highly available (vice versa)

Animals are heterotrophs, what are the types? (Chapter 7)

• Herbivores: Eat plants.

• Carnivores: Eat animal tissue.

• Omnivores: Eat both plants and animals.

• Detritivores: Eat dead/decaying matter.

• Key Example: Mouth part adaptations in Galapagos finches.

Animals have adapted to cope w/ fluctuating temperatures or environmental gradients.

What are the two types of Thermoregulation?

• Endothermy (heats comes from within)

• Ectothermy (get heat from external means)

What is Endothermy?

• Use metabolic processes to heat to maintain constant temp (e.g., mammals, birds). Energetically costly but allows year-round activity.

• “Warm Blooded”

What is Ectothermy?

• Rely on external environment for heat (e.g., reptiles, insects). More energy-efficient but body temp fluctuates, can become sluggish in cold.

• “Cold Blooded”

• How are Thermoregulation strategy restricted by body size and geographic range?

Endotherms

• smaller species = small body = more heat lost due to surface area being small

• Smaller the body the more heat lost to the ENV, bc metabolic processes cant catch up

• Need to consume their body weight in food

• How are Thermoregulation strategy restricted by body size and geographic range?

Ectotherms

• Bigger animal = larger volume = harder to heat bc of surface area

• Body too large = cant absorb heat from ENV

• Larger ectotherms (crocodiles) are restricted to hotter climates

Why are large bodied ectotherms are restricted to warm climates?

• These ectotherms do thermal regulate from the energy in the envir --> this  is hard for large ectotherms bc they have a large volume RELATIVE to their surface area - more volume less surface area

 

• Small animals have an easier time, bc small body = less volume = more surface area

Example of an ectotherm producing own metabolic heat?

• flapping wings before flight to warm up

Energy Conservation strategies for endotherms: Torpor and Hibernation

What is Torpor?

• Short-term, daily reduction in body temperature and metabolic rate.

• They just shut down for a minute

• Ex. Bats hanging upside down during the day

Energy Conservation strategies for endotherms: Torpor and Hibernation

What is Hibernation?

• Long-term torpor, usually seasonal (e.g., during winter).

• 100% shut down (not bears)

• A kind of torpor

• Advantages of the spiky things - protection from animals

• Selection agent: The animals that are trying to eat that fruit

• Advantage: Long beak to get the nectar

• Selection agent: The flower itself

• Advantages: Dispersal

• Selection Agent: Getting away from moms competition, mom also has been there a while so she could have diseases or bugs so you want to get away from that

• Advantages: The houses are made by the male to impress the huzz

• Selection agent: The female birds

What is Population? (chapter 8)

An aggregate of individuals of the same species that are reproductively isolated from other such groups.

Define Metapopulation

A group of spatially distinct subpopulations connected by some degree of migration or dispersal (not completely reproductively isolated).

Define Population Distribution

 is determined by presence and absence potentially interbreeding individuals  (to have a pop, the indiv gotta be able to reproduce)

Define Geographic Range

• Is the spatial distribution of all individuals of a species, regardless of if the indiv are in the same pop or diff pop (where all of the indiv of a particular species are, regardless of if their in the same pop or not)

• Size of range determined by species tolerance to abiotic factors

• 2 types: Ubiquitous Species and Endemic Species

Ubiquitous Species?

Found over a large geographic area (e.g., white oak).

Endemic Species?

Found only in a specific, restricted area, often due to specific habitat needs (e.g., Arkansas oak).

Explain this idea

Just because it has a broad geographic range, doesn’t mean its gonna be found everywhere, their still gonna be in specific habitats

Define Population Size

Is defined by how abundant are its individuals (how many indiv)

• Species abundance = # of indiv of a population

  • Note: for most species its impossible to count all individuals of a population, but can estimate

  Population Density = # of indiv. In a given area

  • Ecologists often subsample the population to get an estimate of species abundance per unit area

What are the 3 types of Population distribution?

• Radnom

• Uniform

• Clumped

What kind of distribution is this?

Clumped - most common

What kind of distribution is this?

Uniform - usual reason is bc of defending territory

What are the different ways population density can be expressed?

• Crude Density

• Ecological Density

Define Crude Density

• Crude density: # indiv./ total area of population  (Black Border)

Define Ecological Density

• Ecological Density: #Indiv./ Area of suitable habitat w/I a pop distribution

  • This one takes into consideration that not all of that area in black border are gonna have wolves, so this density takes the indiv. And divides it my the area where you actually find grey wolves

  • More precise 

The green areas are actually where the wolves reside

Why is it important to see the distribution of individuals among different age classes in a population?

• Provides insight into whether a population is stable, growing (more juveniles), or declining (fewer juveniles). Critical for prediction.

• Decrease: Japan, Increase: Egypt

• Japan decreases bc less babies and Egypt has more babies

Population Dynamics:

How pops vary in size over space and time

Population Ecologists:

Use empirical data and mathematical pop models to understand pop dynamics and predict rends in population size over time

Exponential Growth Models

• N = population size

• r = per capita growth rate (b-d) = constant

• T = Time

• Nt = Number of indiv. in previous generations

What are the assumptions made on the Exponential Growth Model?

• Unlimited resources

• constant birth and death rates “r”

• No Migration (closed system)

• No random events

What happens to the change in numbers of indiv. over time (N/T) when…

r = zero

• N/T = 0

• Population size doesn’t change

What happens to the change in numbers of indiv. over time (N/T) when…

r > zero

• N/T > 0

• Population size increases

What happens to the change in numbers of indiv. over time (N/T) when…

r < zero (negative)

• N/T < 0

• Population size Decreases

Which species is still exponentially growing?

Thomas Austin?