General ecology

Why are amphibians a good example for understanding ecology?

- Can you use this scenario to explain how interactions between organisms and their

environment can affect other organisms and lead to unexpected consequences?

Skin is permeable; pollutant molecules can pass through

easily.

– Eggs have no protective shell.

– They spend part of their life on land and part in water—

exposed to pollutants and UV in both environments.

Can you explain how the scientific method is used in ecology? How do observations and

experimentation work together? What are the main components of experiments and experimental

design? How do different types of experiments fit together?

The scientific method is used in ecology to create hypothesizes on real world observations they make. Observations show a real world thing, while experimentations allows us to isolate that specific thing and test it. the main components of experiments and experimental design include the observation, hypothesis, independent and dependent variable, and treatment and control groups.

different types of experiments fit together to approach a balance with control in the laboratory, but also realism with experiments out in the natural world.

How does ecology compare to environmental science?

Ecology refers to a scientific endeavor, not environmental

activism while environmental science incorporates concepts from the natural

sciences (including ecology) and the social sciences and focuses

on how people affect the environment and how to address

environmental problems.

What is the “balance of nature” and how to modern ecological ideas differ?

The balance of nature is in which natural systems are stable and tend to return to an original state after disturbance and each species play a distinct role in that balance.

Modern ideas now think: Natural systems do not necessarily return to their original state after disturbance.

• Random perturbations can play an important role.

• Different communities can form in the same area under similar

environmental conditions.

• Ecological interactions are more complex than previously thought

One view has not changed: Events in nature are interconnected. A

change in one part of an ecological system can alter other parts of

that system.

What are the scales of ecological study? What are the levels in the biological hierarchy?

Scales:

Spatial scales: – Small—e.g., soil microorganisms – Large—e.g., atmospheric pollutants

• Temporal scales: – Short—e.g., leaf response to sunlight – Long—e.g., species change over geologic time

Levels

Population: A group of individuals of a single species that live in a particular area and interact with one another.

• Community: An association of populations of different species living in the same area at the same time.

Ecosystem: A community of organisms plus their physical environment.

• Landscapes: Areas with substantial differences, typically including multiple ecosystems.

• All the world’s ecosystems comprise the biosphere—all living organisms on Earth plus the environments in which they live.

defs for: controlled experiment, ecology, environmental science, evolution, adaptation, natural selection,

Controlled experiment: Experimental groups are compared with a control group that lacks the factor being tested.

Ecology: the scientific study of how organisms affect, and area affected by, other organisms and their environment.

Environmental science incorporates concepts from the natural sciences (including ecology) and the social sciences and focuses on how people affect the environment and how to address environmental problems

Evolution: 1. Change in genetic characteristics of a population over time. 2. Descent with modification—organisms gradually accumulate differences from their ancestor

Adaptation: A characteristic that improves survival or reproduction.

Natural selection: Individuals with certain adaptations tend tosurvive and reproduce at a higher rate than other individuals.

defs for producers (autotrophs), Net primary production (NPP), consumers (heterotrophs), nutrient cycle

Producers (autotrophs) use energy from an external source (e.g., the sun) to produce their own food. Also called primary producers.

Net primary production (NPP): Energy captured by producers minus amount lost as heat in cellular respiration.

Consumers (heterotrophs) get energy by eating other organisms or their remains.

nutrient cycle: nutrients are continuously recycled from the physical environment to organisms and back again

Acclimatization vs. adaptation

Acclimatization: adjusting to stress through behavior or physiology, short term reversible change

adaptation: individuals with traits that enable them to cope with the stress are favored; over time, these genetic traits become more frequent in the population.

what two options do animals have with coping environmental variation?

tolerance and avoidance

defs for stress, thermoneutral zone, lower critical temperature, Hyperosmotic, isosmotic, hypoosmotic, turgor pressure

stress: Environmental changes result in decreased rates of physiological processes, lowering the potential for survival, growth, or reproduction.

thermoneutral zone: Range of environmental temperatures over which a constant basal metabolic rate can be maintained.

lower critical temperature: : When heat loss is greater than metabolic production; body temperature drops and metabolic heat generation increases

Hyperosmotic: more saline than an organism’s cells

Isosmotic: same salinity

Hypoosmotic: less saline

turgor pressure: as water moves into a cell, it expands and presses against the cell wall

Ectotherms vs Endotherms (Costs and Benefits)

ectotherms: regulate body temperature mainly through energy exchange with the external environment. Ectotherms generally have a greater tolerance for variation in body temperature than endotherms

Endotherms: rely primarily on internal heat generation— mostly birds and mammals. High demand for energy (food) for metabolic heat production

Surface area to volume ratio and heat/water exchange

Smaller surface area relative to volume decreases the animal’s ability to gain or lose heat.

torpor vs hibernation

torpor: temporary dormant state where body temperature and basal metabolic rates are low, which conserves energy. some endotherms may do daily torpor.

hibernation: longer periods of torpor, possible for animals that store enough energy

Water regulation in plants and animals

plants: must take up water from soil to replace water lost in atmosphere, can save water my closing their stomates, shedding leaves to cope with water loss. some have thicker cuticles to slow water loss. if too much water may grow air channels in root tissues or roots that grow vertically above the soil

Animals: Multicellular animals must also maintain water balance. Specialized organs for gas exchange, excretion, etc. create localized areas of water and solute exchange. Most animals are mobile and can move to different environments to maintain water balance.

Sources of energy

radiant energy: sunlight

chemical energy: stored in bonds of food molecules

kinetic energy: movement of molecules; measured as temperature

defs for autotrophs, heterotrophs, photosynthesis, chemosynthesis

autotrophs: assimilate energy from sunlight (photosynthesis) or inorganic compounds (chemosynthesis), and convert it to chemical energy in bonds of organic molecules

heterotrophs: obtain energy by consuming organic compounds from other organisms (originally synthesized by autotrophs).

photosynthesis: sunlight provides the energy to take up CO2 and synthesize organic compounds.

chemosynthesis: energy from inorganic compounds

light reaction, dark reaction, photorespiration

light reaction: pigments absorb energy from discrete units of light, called photons. The energy is used to split water and provide electrons. The electrons are passed to other molecules on the membranes, where they are used to synthesize ATP and NADPH.

dark reaction: Using AAP and NADHP converting CO2 into glucose

photorespiration: O2 is taken up, carbon compounds are broken down, and CO2 is release

C3, C4, CAM

C3: Co2 enters the bundle sheath cell and is fixed by RUBISCO

C4: minimizes photorespiration by storing CO2 in a four carbon compound in the mesophyll cell, where it is releases the CO2 into the bundle sheath cell, Uses more ATP, would be seen in environments with hotter environments.

CAM: minimizes water loss by opening stomates at night when it’s cooler and humidity is higher, and closing them during the day. – Night: CAM plants take up CO2 using PEPcase to make a 4-carbon organic acid and store it in vacuoles. – Day: the molecule is broken down to supply CO2 for the Calvin cycle. High CO2 concentrations reduce photorespiration.

defs for Evolution, Gene, Allele, mutation, adaptation, adaptive evolution

Evolution: the change in allele frequencies over time in a population

Gene: made of DNA; specify (encode) protein structure

allele: two or more forms of genes

mutation: A change to a DNA sequence

adaptation: Features of organisms that improve their ability to survive and reproduce.

adaptive evolution: traits that confer advantages tend to increase in frequency over time.

phenotype vs genotype

phenotype; an individuals observable traits resulting from their genotype and their interaction with the environment

genotype: genetic makeup of an individual; represented by letters

three types of natural selection

directional: Individuals at one phenotypic extreme are favored.

stabilizing: Individuals with an intermediate phenotype are favored.

disruptive: Individuals at both phenotypic extremes are favored.

genetic drift and the four effects it has on small populations

genetic drift: Occurs when chance events determine which alleles are passed to the next generation

1. Allele frequencies fluctuate at random; some may disappear, others may become fixed.

– 2. Genetic variation of the population is reduced.

– 3. Frequency of harmful alleles can increase if they have only mildly deleterious effects.

– 4. Chance events may lead to allele fixation in one population and loss from another population.

Gene flow and the 2 effects it has

gene flow: Alleles move between populations via movement of individuals or gametes.

1. Populations become more similar.

– 2. New alleles can be introduced into a population (acts similarly to

mutation).

Constraints of evolution

Lack of genetic variation: if there is no beneficial allele, adaptive evolution at that gene cannot occur. Advantageous alleles arise by chance, not “on demand.” Example: Initially, mosquito populations lacked alleles for pesticide resistance so the pesticides were effective.

Evolutionary history: Natural selection works on traits that already exist. Organisms have certain characteristics and lack others because of their ancestry. – Example: Dolphins evolved from terrestrial mammals; they have lungs and cannot “breathe” underwater.

Ecological trade-offs: The ability to perform one function may reduce the ability to

perform another function. Adaptations are the product of compromises in the abilities of organisms to perform different and sometimes conflicting functions.

defs for life history strategy, phenotypic plasticity, allocation, asexual reproduction, isogamy, anisogamy

life history strategy: the overall pattern in average timing and nature of life history events.

phenotypic plasticity: One genotype produces different phenotypes under different environmental conditions.

Allocation: The relative amounts of energy or resources that an organism devotes to different functions

Asexual reproduction: Simple cell division (binary fission)—all prokaryotes and many protists. Some multicellular organisms reproduce both sexually and asexually (e.g., corals).

isogamy: gametes are in equal size

Anisogamy: Most multicellular organisms produce gametes of different sizes; the egg is usually much larger and contains nutritional material.

complex life cycles

At least two stages with different body forms that live in different habitats and eat different foods. These life cycles are common in insects, marine invertebrates, amphibians, and some fishes. Also seen in parasites

metamorphosis

Abrupt transition between larval and juvenile stages.

semelparous vs iteroparous

Semelparous: species reproduce only once.

Iteroparous: species can reproduce multiple times; most animals, many kinds of plants.

r-Selection vs. K-selection

r-selection: Selection for high population growth rates; an advantage in newly disturbed habitats and uncrowded conditions. • r: intrinsic rate of increase of a population. Short life spans, rapid development, early maturation, low parental investment, high reproduction rates.

K-selection: Selection for lower growth rates in populations that are at or near K, the carrying capacity. • Advantage in crowded conditions; efficient reproduction is favored. Long-lived, develop slowly, late maturation, invest heavily in each offspring, low reproduction rates

defs for dispersal, dormancy, paedomorphosis, sexual selection, anisogamy, mating systems,

dispersal: Movement of organisms or propagules from their birthplace. – Small offspring are well-suited for dispersal. – Dispersal can reduce competition among close relatives, allow colonization of new areas, or escape from areas with diseases or high predation

dormancy: State of suspended growth and development in which an organism can survive unfavorable conditions. – Small seeds, spores, eggs, and embryos are best suited to dormancy—less metabolic energy is needed to stay alive. – Some larger animals also enter dormancy.

paedomorphosis: mature sexually while retaining larval morphology and habitat

sexual selection: Individuals with certain characteristics gain an advantage over others of the same sex solely with respect to mating success

Anisogamy: female invests more to produce a large egg, and often continues to invest more in the offspring (incubating eggs, caring for young, etc.)

mating systems: number of mating partners and patterns of parental care.

How does evolution play a role in behavior? What is the difference between proximate and ultimate causes?

Evolution plays a role in behavior because it helps to mold animals to do decisions based on their proximate and ultimate causes.

Proximate causes (immediate)—or how the behavior occurs.

• Ultimate causes—why the behavior occurs; the evolutionary and historical reasons.

Optimal foraging theory Equation and Graphs Examples? Limitations?

OFT: Animals will maximize the amount of energy acquired per unit of feeding time. – If energy is in short supply and impacts an animal’s fitness, then selection should act on foraging behavior to increase efficiency.

equation: Enet: net energy obtained from a food source Egross: total energy from a food source h: time spent handling the food source s: time spent searching for the food

Example: Birds choosing the largest of available mealworms

Defenses of prey

Prey species have evolved a range of defenses against their

predators. • Antipredator behaviors include making themselves less visible,

ways to detect predators, prevent attack, or escape once

attacked. • Prey may perform risky activities (such as foraging) during

times of day when predators are not active.

Mating Behavior

Males and females often differ in physical appearance; males often possess weapons such as horns, or gaudy ornaments.

• The sexes may also differ in behavior. Many males fight, sing loudly, or perform strange antics to gain access to females.

Parental Investment and exceptions to the rule

Females and males often differ in amount of energy and resources they invest in their offspring. • In many species, males don’t provide any parental care. Because of these costs, females tend to be choosy, males compete for females and often produce more offspring during their lifetimes than females. Differences in gamete size and parental care relate to mating behavior:

exceptions to the rule: n some species females compete for males. Males provide more parental care and females compete for the right to mate with choosy males

Ecological influence on mating

Mate choice can be altered by number and locations of potential mates, mate quality, food availability, and presence of predators or competitors.

Distribution vs. Abundance

Distribution: Geographic area where individuals of a species occur.

• Abundance: Number of individuals in a given area.

defs for population, population size, population density (How to determine what a population is (what are the criteria?))

Population: A group of individuals of the same species that live in a particular area and interact with one another.

• Population size (# of individuals)

• Population density (# of individuals per unit area).

Methods of measuring populations – how does the method depend on the characteristics of the species?

1. Area-based counts: individuals in a given area or volume are counted. – Used most often to estimate abundance of sessile organisms such as plants. – Quadrats: Sampling areas of specific size; must be a good representation of the entire area and are chosen at random or placed on a grid. – Individuals are counted in several quadrats; counts are averaged to estimate population size.

2. Distance Method: Distance of individuals from a line or point are converted into estimates of abundance. – Line transects: observer travels along a randomly placed line, counts individuals and determines distance from the line. – A detection function converts distance measurements into an estimate of the absolute population size.

3. Mark–recapture studies are used for mobile organisms. – A subset of individuals is captured and marked or tagged, then released. – At a later date, individuals are captured again, and the ratio of marked to unmarked individuals is used to estimate population size.

Dispersion: regular, random, clumped

Regular dispersion: Individuals are evenly spaced throughout their habitat.

– Random dispersion: Individuals are randomly spaced.

– Clumped dispersion: More common in natural populations.

defs for line transects, endemic, dispersal, metapopulation, geographic range, migration

line transects: observer travels along a randomly placed line, counts individuals and determines distance from the line.

endemic: species occurs in one location early and nowhere else on Earth

Dispersal: Movement of individuals into (immigration) or out of (emigration) an existing population.

• Metapopulation: Group of geographically isolated populations linked by dispersal.

• Geographic range, or distribution, of a species might consist of one or multiple metapopulations.

Processes Important to Distribution and Abundance

Habitat suitability determines distribution and abundance.

Abiotic factors: Moisture, temperature, pH, light, nutrients, etc.

Some species tolerate broad ranges of physical conditions, others have narrow ranges.