Ecology Quiz 1

Ecology is

The study of relationships between organisms and their environment

Zoonosis

Disease due to pathogen that resides in a non-human vertebrate

Reservoir

Non-human vertebrate that maintains/amplifies the pathogen

Emerging infectious disease

Appears suddenly OR increase dramatically in incidence or geographic extent

Vector-borne disease

Pathogen moves from host-to-host via blood-feeding anthropod

In the black-legged tick example, what is the relationship between ticks, mice, Lyme disease, and acorns?

On years where trees mast (produce more acorns), the mice have lots of food and can reproduce more. Therefore, the FOLLOWING year, there’s a boom of mice. After THAT year, ticks peak, and along with it, Lyme disease cases

In the black-legged tick example, which year does Lyme disease peak?

Year 3

Evolution

a change in allele frequencies over time

What are the 4 mechanisms for evolution?

• Mutation

• Natural Selection

• Genetic drift

• Gene flow

Which evolutionary mechanism is the source of all variation?

Mutation

What do natural selection, genetic drift, and gene flow all have in common?

They change the frequency of variants

Where does variation come from?

Mutations in alleles

What makes up the gene pool?

All alleles from ALL individuals in a population

Evolution is driven by……

Ecological interactions among organisms and with their environment

What kinds of mutations could we have?

Point mutations (single nucleotides)

Chromosomal rearrangements

Mutations have effects on…

Function and fitness

What kinds of effects can mutations have on function?

Loss of function

Gain of function

What kinds of effects can mutations have on fitness?

• Lethal effects

• Neutral effects

• Deleterious effects

• Beneficial effects

Is mutation the direct cause of allele frequency changes?

No! It’s too rare

Is all variation the result of different genotypes?

No! Think tans due to sun exposure

Phenotype is a product of…

genotype + environment

What is phenotypic plasticity?

The ability of one genotype to produce more than 1 phenotype when exposed to different environments

• Hydrangea example

What does no plasticity mean?

Change in environment does not change trait value

What does high variable plasticity mean?

Strong genotype-by-environment relationship

What is the plasticity example in ducks?

In seasons when male-to-male competition for access to mates is greater, males grow longer penises

Genes did NOT change, but the environment did

What is the guppy example with natural selection?

Endler noticed that guppies at the top of the waterfall are colorful (no predators). Guppies at the bottom are not (blend into environment bc predators).

Ran experiment: 2 different backgrounds (course gravel and fine gravel) and after 15 generations, the guppies closely matched their gravel

Fish with these traits survive long enough to breed… natural selection!

What are the 3 things required for evolution by natural selection?

1) There is variation in traits

2) There’s differential reproduction (some survive to reproduce and some do not)

3) There is heredity (surviving individuals have babies that are similar to them bc of shared genes - CONSISTENT CHANGE)

At what level does selection occur? At what level does evolution occur?

Selection occurs at level of the individual (traits are properties of individuals)

Evolution occurs at level of population

What are the 3 types of selection

1) Directional selection

• Selection that acts to push some aspect of a pop. phenotype in one particular direction

2) Stabilizing selection

• Selection favoring phenotypes that are intermediate in some aspect

3) Disruptive selection

• Selection favoring extreme phenotypes at the expense of intermediate phenotypes

Adaptive evolution

Increase in average fitness of the population in their environments

Adaptations

Features of organisms that improve their ability to survive and reproduce in their environments

Fitness

Relative genetic contribution of individuals to future generations

• Depends on your population.

• Are you higher in fitness RELATIVE to people in your population?

Population

Group of individuals of the same species inhabiting a particular area

What is the mechanism that consistently causes adaptive evolution?

Natural selection

What is genetic drift?

Stochastic process - Occurs when chance events determine which alleles are passed on to the next generation. Totally random

When is genetic drift the most important?

For small populations

• founder effects

• Bottlenecks

What happens with genetic drift within populations? (A consequence!)

Loss of alleles through fixation

What happens with genetic drift between/among populations? (A consequence!)

Increased diversity bc fixation is random and differs across populations

Why is genetic drift important for small populations?

One consequence of drift is loss of alleles, which means reduced diversity within populations. BAD!!

Why is reduced diversity bad?

• Harmful alleles can increase in frequency by chance

• Less variation on which selection can act (won’t be able to respond in adaptive direction if environment changes)

  Prairie chicken example

What is gene flow?

Movement of alleles between populations

• introduces new alleles to populations

• Homogenizes different populations genetically making them more similar to one another

Gene flow homogenizes….

populations genetically

How does the example of the Male Teleogyllus oceanicus (cricket)’s call to attract females bring together selection, drift, and gene flow?

Flatwing males were missing the scraper and were therefore silent.

This meant they were protected from the parasitoid fly and survived to be able to mate with females. Not choosy females were favored in small island populations (selection)

In small founding populations, genetic drift took place upon island colonization. More males becoming silent.

Crickets moved from island to island in the Pacific (gene flow)

Research definition

Systematic study to gain a fuller scientific knowledge or understanding of a subject

What is applied research?

Research to gain knowledge or understanding to meet a specific need. Solving problems.

What is basic research?

Research directed toward fuller knowledge or understanding of fundamental aspects of phenomena without specific applications or products in mind

• generating NEW knowledge. Exploring for exploring’s sake

• Does NOT aim to solve a problem

• Can produce discoveries that unexpectedly contribute

What are proximate causes?

Mechanistic answers that answer the “how”

• concerned with the environmental stimuli and underlying genetic, physiological, developmental, and anatomical mechanisms

What are ultimate causes?

Address evolutionary significance and answer the “why”

• concerned with selection (natural/sexual), fitness, evolutionary history

Is this an applied or basic research question?

How does the amount of light affect growth of shade tolerant versus intolerant plants?

Basic

What mechanisms can get ecological answers?

Natural history observations

Analysis of patterns

experiments

Quantitative models

What does a good experiment have?

Manipulation and controls, replication, and randomization

What do you do when you can’t measure a whole population?

Sample it.

• all metrics have some distribution — there’s variation among individuals -- and their average is assumed to have some “true” value

What are the 3 metrics we are concerned with?

1) Central tendency

2) Spread

3) Confidence (how certain we are about our estimates)

What are the 3 measures of central tendency?

• Mean (average)

• Median (middle value)

• Mode (most common value)

Why don’t we always just use the mean?

The mean is sensitive to extreme values, which could skew data dramatically

What is standard deviation?

How far away a value is from the mean

• Small st dev = data points CLOSE to the mean

• Big st dev = data points SPREAD over large # of values

What is variance?

Average squared distance of each data pt. from the mean

Independent variable

• On x-axis

• Thought to be the cause of the observed effect

Dependent variable

• on y-axis

  • Response variable

Categorical (discrete) variable

Variable with separate, indivisible categories

Continuous variable

Variable that can take on number values

Why are temperature and water relations important for evolution/life?

The physical world can constrain life and environmental conditions can be very variable, but organisms are adapted to a narrow range of conditions

All of the following are likely examples of trade-offs, except for:

The brightest red guppies are also the most parasite resistant

Measuring fitness is complicated because

• organisms can mate outside of the pair bond

• There are lots of components and proxies (# of children, # of grandchildren, etc.)

• Animals are difficult to follow throughout life

What are trade-offs in evolution?

The ability to perform 1 function reduces the ability to perform another

• Compromises in ability of organisms to perform many different, sometimes conflicting functions

What was the experiment with E. coli warm or frozen demonstrating?

Question was: Does adaptation to a low temperature reduce fitness at a high temperature?

E. coli adapted to 20º C because their fitness was greater than their ancestors. So no, not exactly.

Principle of allocation!!

Principle of allocation

Energy allocated to one of life’s functions will reduce the amount of energy available for other functions

What are the 3 ways organisms adapt to temperature extremes?

1) Storage

2) Dormancy

3) Thermoregulation

What is storage for adapting to extreme temperatures?

Reliance on resources accumulated under more favorable conditions

• Ex) Cacti storing water, squirrels remembering where food is

What is dormancy for adapting to temperature extremes?

Becoming inactive

• Ex) Hibernation in mammals, diapause in insects

What is thermoregulation in adapting to temperature extremes?

Maintaining particular internal temperatures.

Behavioral:

• Reptiles sunning

• Cactus wrens in microhabitats

Internal:

• Countercurrent exchange

• Skunk cabbage metabolize starch from root and melt snow around it to bloom

How do you balance water in an organism? What is the “equation?”

Wia = Wd + Wf + Wa - We - Ws

Wia = internal water of animal

Water sources:

• Wd = water taken in by drinking

• Wf = water taken in by food

• Wa = water absorbed from air

Water Losses:

• We = water lost by evaporations

• Ws = water lost through secretions and excretions

Ex) Kangaroo Rats. How do they balance water?

They have both physiological (producing concentrated urine, minimizing evaporation losses) and behavioral (venturing above ground at night) adaptations to conserve water.

Ex) Fog-basking beetles. How do they balance water?

They have an adaptation where they can take water in from the surrounding fog

The internal water balance of animals depends on

both water sources and losses

True or false: Both plants and animals can thermoregulate internally

True

Ecosystem

A biological community plus all the abiotic factors that influence the community

Climate

the average daily weather for an extended period of time at a given location

Weather

Current condition of temperature, precipitation, humidity, and cloud cover

What’s the difference between climate and weater?

Climate is what you expect, weather is what you get

Why are we interested in the climate in ecology?

Climate drives abiotic environment (availability of water and degree of heat)

Global biomes are predictable from climate

Biome

Large geographic area characterized by similar flora, fauna, and microorganisms

What does this tell us?

Vegetation follows precipitation patterns

What are the (4) things that have variation that global biomes are predictable from the climate?

• Solar radiation

• Precipitation

• Atmospheric and ocean circulation

• Topography

What is the major driving force behind climate?

Solar radiation

How does solar radiation affect Earth’s climate?

Climate variation mostly caused by uneven heating of its surface by the sun (due to sun angle and path length)

• Tilt of the earth results in seasonal changes in climate

Can affect species interactions (Mountain Pine Beetle example)

Explain Mountain Pine Beetle example and how it relates to solar radiation

The Mountain Pine Beetle attack trees under stress, but move to healthy trees. Beetles bore in, lay eggs, and eat the layer giving nutrients to the tree.

Usually, winters freeze and kill them, but warming causes beetle increases because winter in CO is no longer cold enough to kill larvae.

Results in millions of trees lost

Explain surface heating and the uplift of air

Sun heats air near equator. Less dense warm air rises and forms clouds. Once in the atmosphere, it spreads north + south, cools, rises, until it goes back into Earth

• Hadley Cells

What are hadley cells?

global-scale tropical atmospheric circulation patterns where warm air rises at the equator, moves poleward, cools, and sinks

There are multiple air circulation cells that are not just at the equator

What do global ocean currents do?

Distribute heat around the globe, generating warm coastal climates

• One reason we don’t have perfect bands of climate at latitude

Rain shadow

Air picks up moisture over water or flat land, hits the mountain and rises/cools, releasing moisture. As air descends on the other side, it warms, creating rain

Why isn’t the east side of the Rockies as lush as the west side?

Because of rain shadows. By the time cool air gets to eastern side, it’s lost a lot of its moisture

Why does climate differ across elevations?

Due to adiabatic heating/cooling

Adiabatic heating/cooling

Temperature decreases as air pressure decreases. As pressure decreases, gases expand, occupy larger volume, and lead to decreased temperatures (uses energy)

Are south or north facing slopes warmer?

South. They receive more incoming sunlight and are warmer and drier.

Slope aspect