Ecology

finals practice

Define Ecology

1. The scientific study of interactions between organisms and their environment

2. the scientific study of interactions that determine the distribution (geographic location) and abundance of organisms.

What is the Ecological Hierarchy (name each and describe them)

1. Organism - Single individual

2. Population - a group of individuals of a species that are living and interacting in a particular area.

3. Community - Association of populations of different species in the same area

4. Ecosystem - community of organisms plus the physical environment.

5. Biosphere - all living organisms on earth plus the environment in which they live.

Describe how energy works in an ecosystem

• Energy moves through the ecosystem in a single direction

• it cannot be recycled

• nutrients are continuously recycled form environment to organism and back again.

Why are amphibians “biological indicators”

• permeable skin: pollutant molecules can pass easily

• eggs have no protective shell

• spend part life in land, part in water (exposed to UV in both)

What are the steps in the scientific method?

1. Make observations and ask questions

2. use previous knowledge or intuition to develop hypotheses

3. evaluate hypotheses by experimentation, observational studies, or quantitative models

4. use the results to modify the hypotheses, pose new questions or draw conclusions about the natural world.

Ecological experiments

the spatial scale of ecology ranges from lab experiments, to small-scale field experiments, to large-scale experiments that alter major components of an ecosystem.

Two ways the physical environment influences an organism’s ecological success?

1. extreme conditions can exceed tolerance limits and impact survival.

2. availability of energy and resources impacts growth and reproduction

Why are plants good indicators of the environment?

They do not move.

Climate envelope

the range of conditions over which a species can occur (survive and reproduce)

Physiological ecology

the study of interactions between organisms and the physical environments that influence their survival and persistence.

• physiological processes have optimal conditions for functioning

• deviations from the optimum reduce the rate of process.

Stress

environmental change results in decreased rates of physiological processes, lowering the potential for survival, growth, or reproduction

acclimatisation

adjusting to stress through behaviour or physiology

• usually short-term, reversible

How does adaptation work?

over time, natural selection results in the adaptation of a population to environmental stress. Individuals with traits that enable them to cope with stress are favoured. Over time these genetic traits become more common.

True or False, adaptation and acclimatization are not similar

False, they are in fact similar because both processes involve a change that lowers stress.

• the ability to acclimatise represents a type of adaptation.

• adaptation is long term, acclimatization is short.

Ecotypes

populations with adaptations to unique environments.

• can eventually become separate species as population diverge and become reproductively isolated.

Environmental temperature

large variation throughout the biosphere, survival and function of an organism is tied to their internal temperature.

Dormancy

Where some organisms can survive periods of extreme heat or cold by entering a state of dormant, in which little or no metabolic activity occurs.

What are enzymes?

• Protein-based molecules that catalyze biochemical reactions

• have narrow temperature ranges for optimal function where they stay structurally stable.

What happens to an enzyme at high temperatures?

Enzyme function is destroyed and they lose their structural integrity (denatured)

How does temp affect properties of cell membranes?

Cell membranes are made of two layers of lipid molecules

• at low temps, these lipids can solidify, embedded proteins cannot function, cell leaks metabolites

• plants that thrive at low temps have higher proportions of unsaturated lipids (double bonds).

Ectotherms

regulate body temperature through energy exchange with the environment.

• their surface area-to-volume ratio is important in exchanging energy with the environment.

  • higher surface area= more contact with environment

  • smaller= less contact but also ness control of internal temp.

Endotherms

rely primarily on internal heat generation - mostly birds and mammals

• can maintain internal temps near optimum for metabolic functions

• extend geo range.

Cryonics

the preservation of bodies by freezing, in hopes of reviving them later on

• freezing water is limited to outside of cells

  • ice-nucleating proteins outside cells serve as sites of slow, controlled ice formation

  • inside are solutes with lower freezing points.

Thermoneutral zone

range of environmental temps over which a constant basal metabolic rate can be maintained

Lower critical temperature

when heat loss is greater than metabolic production; body temp drops and metabolic heat generation increases.

Torpor

a dormant state where body temp and basal metabolic rates are low, which conserves energy

• energy reserves needed to come out of torpor

• larger animals can stay dormant longer as they can store more energy

Hibernation

long periods of torpor (dormancy) that become possible for animals that can store more energy

Conduction

transfer of energy from warmer to cooler molecules

Convection

heat energy is carried by moving water or air

Evapotranspiration

heat loss that occurs through transpiration and surface evaporation

Transpiration

• important evaporative cooling method for leaves

• evaporation of water from inside the plant

• Can be controlled by guard cells surrounding leaf openings called stomates

T/F: transpiration is a good mechanism when soil water supply is limited

False, transpiration needs a lot of water so when it becomes limited it is not a good mechanism

• will cause the leaves to die.

Pubescence

hairs on leaf surfaces that reflect solar energy, lowering the amount of solar radiation absorbed by the leaf’s surface.

• can also lower effectiveness of convective heat loss, creating a trade-off

Boundary layer

a zone of turbulent flow due to friction next to a leaf’s surface

Autotrophs

assimilate radiant energy from sunlight

Heterotrophs

Obtain their energy by consuming organic compounds from other organisms

Holoparasites

plants that have no photosynthetic pigments and get energy from other plants (heterotrophs)

Photosynthesis

(most autotrophs) sunlight provides the energy to take up CO2 and synthesize organic compounds.

Chemosynthesis

Energy from inorganic compounds is used to produce carbohydrates.

What are the two major steps in photosynthesis?

1. light reactions: light harvested, used to split water and provide electrons to make ATP and NADPH

2. Dark reactions: CO2 is fixed in Calvin cycle carbohydrates synthesized.

What does photosynthetic rate determine?

supply of energy, which in turn influences growth and reporduction

Light response curve

Shows the influence of light levels on photosynthetic rate

Light compensation point

Where CO2 uptake is balanced by CO2 loss by respiration

Saturation point

when photosynthesis no longer increases as light increases

T/F leaves at high light intensity are thinner

False, they are thicker and have more chloroplasts

What are the two ways temp. influences photosynthesis

1. it effects on the rates of chemical reactions

2. influences the structural integrity of membranes and enzymes

T/F most enzymes are made of nitrogen

true

T/F nitrogen levels affect photosynthesis levels

true

Why don’t plants allocate more nitrogen to their leaves to increase photosynthetic rate

1. supply of nitrogen is low, compared to demand. Also needed for other things such as growth and metabolic function

2. increasing nitrogen conc. increases chances herbivores will eat leaves. As they are usually nitrogen starved.

Rubisco

the key enzyme for carbon fixation, can catalyze two competing reactions:

1. carboxylase reaction for photosynthesis

2. oxygen reaction for photorespiration

Evolution

Viewed as the genetic change (allele frequencies), over time or as a process of descent with modification.

• populations evolve, individuals do not.

T/F natural selection, genetic drift, and gene flow can cause allele frequencies in a population to change over time.

True

T/F natural selection is the only evolutionary mechanism that consistently causes adaptive evolution

True

Inherited traits

traits passed onto offspring

Basic principles of genes

• genes are made of DNA that encode for protiens

• A gene can have alleles that create different versions of the protein coded for.

• the genotype represents two copies of each gene, one inherited from mother and one from father.

Evolution regarding descent

shared ancestry and shared characteristics

evolution regarding modification

the accumulation of differences

Natural selection

individuals with certain genetically determined characteristics survive and reproduce more successfully than other individuals.

• can be responsible for the “modification" part of evolution

• increases advantageous alleles.

Four processes that influence evolution

1. mutations

2. natural selection

3. genetic drift

4. gene flow

Mutations

cause the allele frequency in a population to change over time.

• a change in the DNA of a gene

• arise during events such as copying errors during cell division, mechanical damage, exposure to mutagens etc.

• VERY RARE, but needed for evolution

Recombination and independent assortment of chromosomes

offspring have different combinations of alleles that differ from their parents.

• mutations provide the raw material, this rearranges the raw material into new combinations

3 types of natural selection

1. directional selection

2. stabilising selection

3. disruptive selection

Directional selection

individuals at one phenotypic extreme are favoured over other individuals

• ex: large favoured over small individuals

Stabilizing selection

individuals with an intermediate phenotype are favoured

• ex: mid-sized individuals favoured

Disruptive selection

individuals with either of the extreme phenotype are favoured

• ex: small and large individuals favoured over mid-sized.

Genetic drift

occurs when chance events determine which alleles are passed to the next generation.

• significant only for small populations

• causes allele frequency to fluctuate randomly.

Fixation

an allele that occurs in a population at frequency of 100%

Gene flow

allele move between populations via movement of individuals or gametes.

• populations become more similar

4 ways genetic drift are related to effects on evolution

1. causes allele frequency to fluctuate randomly over time in small populations.

2. reduced the genetic variation, making individuals genetically similar

3. increases frequency of harmful allele

4. increases genetic differences between populations because random events may increase allele frequency in one pop. and be lost in another.

Adaptations

features that evolve by natural selection and improve an organism’s ability to survive and reproduce in its environment.

4 long term patterns of evolution shaped by large-scale processes

1. speciation

2. extinction

3. mass extinction

4. adaptive radiation

speciation

the process by which one species splits into two or more species

• most commonly occurs when a barrier prevent gene flow between pop of species

genetic barrier

when a new population becomes established from the parental population, or when isolation is induced by continental drift

ecological barrier

when a barrier to gene flow is established between populations, they will diverge genetically overtime.

adaptive radiation

repeated speciation events increases the number of species ina group

Reproductive barrier

caused by geographic and ecological barrier

Evolutionary tree

branching diagram representing the evolutionary history of a group

mass extinction

large proportions of earths species were driven to extinctions in a relatively short period of time.

Life history

consists of an individual’s major events related to its growth, development, reproduction, and survival

• life history events are adaptations

allocation

the relative amounts of energy or resources that an organism devotes to different functions

phenotypic plasticity

a single genotype may produce different phenotypes under different environmental conditions

fitness

the genetic contribution of an organism’s descendents to future generations determined by reproductive rates of the parents and the survival rates of both the parents and offspring

isogamy

production of equal sized gametes

anisogamy

the production of different sized gametes (most common for multicell organisms)

trade off

allocate limited energy or resources to one function at the expense of another.

parental care

invest time and energy to feed and protect offspring

T/F: life cycles are simple

False, very very complex

complex life cycle

at least two distinct stages that differ in their habitat

Dispersal

The movement of organisms from their birthplace

• provides advantages, such as reducing competition in an area

Semelparous Species

Reproduce only once

Iteroparous species

have the capacity to reproduce multiple times

r-selection

selection for high population growth rates

k-selection

selection for slower rates of increase, which occurs in populations that are approaching K (carrying capacity)

The meaning behind K

The carrying capacity or stable population size for their environment.

What are the 3 plant life history patterns?

1. Competitive (low-stress, low-disturbance)

2. Ruderal (low-stress, high- disturbance

3. Stress tolerant (high-stress, low-disturbance)

Behavioural ecology

The study of the ecological and environmental basis of animal behaviour

What does ‘proximate causes’ mean in behavioural ecology?

(immediate) how the behaviour occurs

What does ‘ultimate causes’ mean in behavioural ecology

why the behaviour occurs, the evolutionary and historical reasons

T/F: evolution is the basis for adaptive behaviour

true, natural selection favours individuals whose behaviours make them efficient in activities that aid in their survival.