Bio II Exam IV (ch. 49, 50, 51, 52)

Ecology (49)

the study of how organisms interact w/ each other and their environment, and increasingly the impact that humans have

5 main levels of ecological study (49)

1. organisms

2. population

3. community

4. ecosystem

5. global/biome

Organismal ecology (49)

level of ecological study

researchers explore morphological, physiological, and behavioral adaptations

e.g., how do individuals interact w/ each other and their physical environment?

Adaptations (49)

heritable traits that increase the fitness of an individual in a particular environment relative to individuals lacking the trait

Population ecology (49)

level of ecological study

researchers focus on how the number and distribution of individuals in a population change over time

e.g., how and why does population size change over species and time?

Population (49)

group of individuals of the same species that lives in the same area at the same time

Community ecology (49)

level of ecological study

researchers focus on the nature of the interactions b/w species and the consequences of those interactions

• might focus on predation, parasitism, and competition

• or explore how communities respond to fires, floods, and other disturbances

e.g., how do species interact, and what are the consequences?

Community (49)

consists of populations of different species that interact w/ each other within a particular area

Ecosystem ecology (49)

level of ecological study

• an extension of organismal, population, and community ecology

researchers study how nutrients and energy move among organisms and through the surrounding atmosphere and soil or water

e.g., how does energy flow and how do nutrients cycle thru the local environment?

Ecosystem (49)

consists of all the organisms in a particular region along w/ nonliving components

• these physical and chemical, or abiotic (non-living) components include air, water, and nonliving parts of soil

Global ecology (49)

level of ecological study

researchers focus on the effects of human impacts on the biosphere

• humans are modifying landscapes and releasing massive amounts of energy and nutrients to the biosphere

e.g., how is the biosphere affected by global changes in nutrient cycling and climate?

Biosphere (49)

thin zone surrounding the Earth where all life exists

• the sum of all terrestrial and aquatic ecosystems

Conservation biology (49)

the effort to study, preserve, and restore threatened genetic diversity in populations, species diversity in communities, and ecosystem function

• biologists of this study are like physicians—they identify threatened environments and propose remedies to preserve biodiversity, clean air, pure water, and productive soils

Abiotic (49)

not alive

e.g., air, water, and some components of soil

Niche (49)

the range of conditions that a species can tolerate and the range of resources it can use

• it’s a product of many abiotic and biotic factors, both present and past

Biotic (49)

living, or produced by a living organism

Dispersal (49)

the movement of individuals from their place of origin to the location where they live and breed as adults

Continental drift (49)

the slow movement of Earth’s surface plates over million of years

Weather (49)

consists of the specific short-term atmospheric conditions of temperature, precipitation, sunlight, and wind

Climate (49)

the prevailing, long-term weather conditions found in an area

occurs in relatively predictable global patterns

Equator (49)

at this area, sunlight strikes the Earth at an angle allowing maximal amount of solar radiation

as Earth’s surface slopes away from here toward the poles, sunlight arrives at lower angles, minimizing energy (and heat)

• sun radiation

areas along here also receive the most moisture

• areas abt 30°N and 30°S latitude are among the driest on Earth

Hadley cell (49)

a major cycle in global air circulation responsible for making the Amazon River basin wet and the Sahara dry

• air heated by sunlight along the equator expands and rises; warm air thus holds a lot of moisture

• as air rises above the equator, it cools and is less able to hold water, producing rain

Seasons (49)

regular, annual fluctuations in temperature, precipitation, or both

Elevation (49)

the height of land above sea level

an important factor b/c temperature decreases as a function of altitude

• it’s colder in the mountains than in lowlands

Rain shadow (49)

the dry region on the side of a mountain range away from prevailing wind

mountain ranges can modify regional climate:

• as moist air blows UP a mountain range, it cools and loses its ability to hold water, producing rain

• the cool, dry air then passes the mountain ridge; the area on this side of the ridge receives little precipitation and is said to be this

Effects mountains and oceans have on climate (49)

oceans have a moderating effecting on temperature

water has a high specific heat, or capacity for storing heat energy:

• water absorbs atmospheric heat in the summer and releases it in winter

• coastal areas generally have more moderate climates than inland areas

• gyres bring warm water to colder latitudes and vice versa

Biome (49)

regions characterized by distinct abiotic characteristics and dominant types of vegetation

e.g., broad-leaved evergreen forests, deserts, grasslands, tundra

Net primary productivity (NPP) (49)

the total amount of biomass generated by the fixation of carbon per year minus amount that is oxidized during cellular respiration

• temperature and moisture influence this

represents organic matter available as food for other organisms

terrestrial environments:

• this is often estimated by measuring aboveground biomass

maximized in sunny, warm, wet conditions

Biomass (49)

refers to the total mass of organisms, and primary producers

Aboveground biomass (49)

the total mass of living plants, excluding roots

Simulation studies (49)

one of the ways scientists study the effects of climate change on biomes

these studies are based on computer models of weather patterns in local regions

predict how temperature and precipitation profiles will change w/ increasing temperatures—and how the distribution of biomes might changes as a result

Observational studies (49)

one of the ways scientists study the effects of climate change on biomes

these studies are based on long-term monitoring at fixed sites around the globe

researchers document changes in key physical variables—temperature and precipitation—as well as changes in distribution and abundance of organisms`

Historical studies (49)

one of the ways scientists study the effects of climate change on biomes

these studies examine the relationship b/w CO₂ levels, climate change, and the distribution and abundance of organisms during events that occurred millions of years ago

Experiments (49)

one of the ways scientists study the effects of climate change on biomes

these are designed to simulate changed climate conditions and to record responses by the organisms present

Salinity (49)

one of the abiotic factors that distinguish streams from oceans

the proportion of solutes dissolved in water in natural environments

has dramatic effects on osmosis and water balance in organisms:

• species are adapted to specific ranges of this

• it’s a major determinant of species distributions

Four abiotic factors that distinguish streams from oceans (49)

1. salinity

2. water depth

3. water flow

4. nutrient availability

Water depth and sunlight availability (49)

one of the abiotic factors that distinguish streams from oceans

water absorbs and scatters light, so the amount and types of wavelengths available to organisms change dramatically as water depth increases

• light availability has a major effect on productivity

biologists use water depth and light to define zones in oceans:

• intertidal zone

• neritic zone

• oceanic zone

• benthic zone

• photic zone

• aphotic zone

Intertidal zone (49)

one of the most common zones in the ocean

consists of a rocky shoreline, sandy beach, or mud flat that’s exposed to the air at low tide but submerged at high tide

Neritic zone (49)

one of the most common zones in the ocean

extends from the intertidal zone to depths of abt 200 m

its outermost edge is defined by the end of the continental shelf—the gently sloping, submerged portion of a continental plate

Oceanic zone (49)

one of the most common zones in the ocean

the “open ocean”—the deepwater region beyond the continental shelf

Benthic zone (49)

one of the most common zones in the ocean

the bottom of the ocean at all depths

organisms in this zone survive by consuming the nutrients that drift down from the photic zone

Photic zone (49)

one of the most common zones in the ocean

the intertidal and sunlit regions of the neritic, oceanic, and benthic zones

in this zone, sunlight is abundant, but nutrients are hard to come by

• when organisms in the zone die, rather than remain there to provide nutrients, they drift down to the benthic zone

Aphotic zone (49)

one of the most common zones in the ocean

areas that do not receive sunlight

Littoral zone (49)

zone in lakes

• comparable to the photic, aphotic, and benthic zones in the ocean

consists of the waters along the shore that are shallow enough for plants to take root

“seashore”

Limnetic zone (49)

zone in lakes

• comparable to the photic, aphotic, and benthic zones in the ocean

water that receives enough light to support photosynthesis but too deep for plants to take root

• it’s offshore

Nutrient availability (49)

in many aquatic ecosystems, nutrients such as nitrogen and phosphorus are in short supply

these levels are important:

• scarcity of nutrients limits growth rates in the photosynthetic organisms that provide food for other species

three types of water flow provide critical nutrients:

1. coastal runoff

2. ocean upwelling

3. lake turnover

Coastal runoff (49)

as water rushes down mountains and streams get wider and slower, nutrients gather, sink, and collect at the bottom as debris

nutrients tend to be plentiful in the shallow estuaries:

• sunlight is also plentiful in estuaries, making them among the most productive environments on Earth

Estuaries (49)

where freshwater rivers meet the ocean

nutrients are plentiful here

sunlight is also plentiful here, making them among the most productive environments on Earth

Ocean upwelling (49)

in certain coastal regions, nutrients (that have fallen to benthic zones) are brought up to the surface by currents that cause upwelling

as the surface water moves away from the coast, it is steadily replaced by nutrient-rich water moving up from the ocean bottom

Lake turnover (49)

each year, glacially formed lakes undergo spring and fall turnovers in response to air temperature changes

in winter and summer, the temperature in these lakes varies along a vertical gradient (thermocline)

Thermocline (49)

“heat-slope”

a gradient in temperature, or thermal stratification

How aquatic biomes are affected by humans (49)

humans have caused direct and indirect changes to the physical, chemical, and biotic properties of aquatic biomes:

• wetlands are filled or drained

• streams are dammed

• water is removed from ponds and rivers for agriculture

• new aquatic anthromes—like reservoirs—have been created

• invasive species such as the zebra mussel have been transported

• fisheries have been overexploited, leading to cascading food-web effects

• debris is intentionally and unintentionally disposed of in aquatic biomes, clogging creeks and creating masses of trash in oceans

• chemicals have been released into aquatic habitats

• global climate change is leading to ocean acidification, which has negative effects on many species

Behavior (50)

an action; a response to a stimulus

Behavioral ecology (50)

a subset of organismal ecology

the study of the behavioral adaptations that have evolved in response to ecological selection pressures

Proximate causation (50)

a type of biological causation

also known as mechanistic causation

explains how actions occur in terms of the growth and function of genetic, neurological, hormonal, and skeletal-muscular mechanisms

Ultimate causation (50)

a type of biological causation

also known as evolutionary causation

explains why actions occur

• based on their evolutionary history and consequences

Proximate causes: consolation behavior (50)

e.g., you see a friend in distress

types of biological consolation:

• neurons in your brain process sensory information and cause changes

  • brain signals adrenal glands to produce cortisol

  • neural signals in pituitary signal hormone oxytocin

• your responses may include consolation behaviors such as speaking softly or physical caresses

Ultimate causes: consolation behavior (50)

traits that strengthen social bonds are favored by natural selection and lead to higher evolutionary fitness:

• increased health

• increased access to resources

• decreased vulnerability to threats

not all behaviors are adaptive in all environments:

• oxytocin-mediated consolation behavior in highly social prairie voles observed, but not in less social meadow voles

Innate behavior (50)

type of behavior that’s inherited and tend to be inflexible to environmental changes

• requires no learning

• shows little variation based on learning or the individual’s condition

Fixed-action patterns (FAPs) (50)

highly inflexible, stereotypical (innate) behavior patterns

e.g., sneezing, yawning in humans, jump-back behavior in kangaroos, rats, etc.`

Learning (50)

an enduring change in behavior that results from a specific experience in an individual’s life

• an adaptive behavioral strategy in changing or unpredictable environments

capacity to do this has genetic basis and varies among individuals

Foraging (50)

food seeking behavior

in most cases, animals have a relatively wide range of foods to exploit over a lifetime

even for species that eat limited foods there are still choices to be made:

• e.g., giant pandas eat almost entirely bamboo, but they still have to choose which bamboo plants to harvest

Ultimate causes: optimal foraging (50)

rover allele is favored at high population density:

• rovers are more likely to find unused food patches

sitter allele is favored at low population density:

• sitters do not waste energy searching for food

results link a proximate mechanism w/ an ultimate outcome:

• in this case, presence of certain alleles is responsible for a difference in fitness in specific types of habitats

Optimal foraging (50)

hypothesis that animals maximize their feeding efficiency

concept expressed as:

• fitness ∝ feeding efficiency ∝ benefits/costs (where ∝ means “is proportional to”)

logic:

• if animals maximize benefits and minimize costs, they will have more time and energy for reproduction and higher fitness

Monogamy (50)

one female mates w/ one male, forming a pair bond

• common in birds but rare in mammals

Polyandry (50)

one female mates w/ two or more males

• rarest of the mating systems

some females choose multiple mates while others are coerced

Polygyny (50)

one male mates w/ two or more females

• sometimes called a harem

often occurs in situations where a male defends a territory of resources

Promiscuity (50)

males and females each have two or more sexual partners

some females choose multiple mates while others are coerced

Sexual selection (50)

type of natural selection that favors individuals w/ traits that increase their ability to obtain mates or choose good mates

two types:

• intersexual selection

• intrasexual selection

Intersexual selection (50)

when individual of one sex chooses individual of another sex as a mate

individuals choose mates that will provide:

• direct benefits to them or their offspring (protection & food)

  • indirect benefits by contributing to “good alleles” to their offspring

Intrasexual selection (50)

two individuals of the same sex compete w/ one another for mates

animals that win physical battles tend to have higher mating success:

• competing for mates can be costly (energy), risk of injury, and other factors

• but it can also result in large benefits—increased fitness due to reproductive success

Migration (50)

the long-distance movement of a population associated w/ a change of seasons

Navigation (50)

movement of individuals in search of food, mates, shelter, and other resources is explored by biologists

biologists distinguish 3 categories of orientation used by animals:

1. piloting

2. compass orientation

3. true navigation

Piloting (50)

one way animals navigate

movement using visual cues and familiar landmarks

• many species use this to find their way

• useful along short distances

• some species of migratory birds and mammals:

  • offspring seem to memorize the route by following their parents south in fall and north in spring

Compass orientation (50)

one way animals navigate

movement that’s oriented in a specific direction

• animals may be able to detect a compass direction and travel along it in a straight line until they reach destination

• using Earth’s magnetic field, chemical cues or sounds

• sun or stars may be used, but over long distances the Earth’s rotation must be factored

during cloudy weather, birds and fish appear to orient using Earth’s magnetic field

two hypotheses for how animals detect magnetism:

1. animals; visual systems—chemical reaction that involves electron transfer among molecules

2. small particles of magnetic iron (magnetite)

True navigation (50)

one way animals navigate

the ability to locate a specific place on Earth’s surface (map orientation)

• animal released in unknown position on globe will know where it' is and can navigate directly home (more precise than compass orientation)

Why do animals migrate? (50)

migratory movements pose enormous challenges and costs (time, energy, and predation risk):

• some arctic terns migrate over 32,000km round trip

hypotheses include increasing reproductive success and increasing access to food

Communication (50)

any process in which a signal from one individual modifies the behavior of a recipient individual

crucial component of animal behavior:

• it’s not enough that a signal is sent, the signal must be received and acted on

type of signal used by an organism correlates w/ its habitat

• signals are diverse: different animals do this by sound, scent, or tactile or visual cues

• each mode has advantages and disadvantages

Honeybees: waggle dance (50)

bees move in a circular pattern w/ straight runs down the middle accompanied by vigorous waggles of the abdomen

this contains info abt food location:

• length of waggle run proportional to food distance

• direction of waggle run correlated w/ direction of food source from hive

• direction of food source communicated relative to current position of sun

Deceitful communication (50)

also known as lying

natural selection has favored the evolution of this:

• can be deceiving individual of the same or of another species

individuals sometimes increase their fitness by providing inaccurate or misleading information

Altruism (50)

behavior that has a fitness cost to the individual exhibiting the behavior and a fitness benefit to the recipient of the behavior

• self-sacrificing behavior

decreases an individual’s ability to produce offspring but helps others produce more offspring

existence of this behavior appears to be paradoxical:

• alleles that make an individual more likely to be altruistic should be selected

Kin selection (50)

natural selection of a behavior that may decrease the chance of survival for an individual but increases that of their kin (who share proportion of their genes)

e.g., black-tailed prairie dogs perform risky behavior called alarm calling:

• alarm callers draw attention to themselves: much greater danger of being attacked

Hamilton’s Rule (50)

model used to assess how an allele that contributes to altruistic behavior could increase in frequency in a population

states that altruistic behavior is most likely when 3 conditions are met:

1. fitness benefits of altruistic behavior are high for the recipient (B is high)

2. altruist and recipient are close relatives (r is high)

3. fitness costs to the altruist are low (C is low)

expressed as Br > C

• where B is fitness benefit to beneficiary

• r is the coefficient of relatedness (measure of how closely actor and recipient are related)

• C is fitness cost to the actor

• B and C are both measured in offspring produced

Direct fitness (50)

derived from an individual’s own offspring

parents can increase this by spending resources to ensure the welfare of their offspring (parental care)

Indirect fitness (50)

derived from helping relatives produce more offspring than they could produce on their own

e.g., a grandparent can increase this by caring for their offspring’s child (grandchild) so that their offspring will have more resources available to have a second child

Inclusive fitness (50)

combination of direct and indirect fitness components

Reciprocal altruism (50)

an exchange of fitness benefits that are separated in time

they help individuals who have either helped them in the past or are likely to help them in future

e.g., vervet monkeys are most likely to groom unrelated individuals that have groomed or helped them in past

Cooperation and mutualism (50)

some behaviors appears altruistic but are selfish b/c they increase (not decrease) direct fitness of animal exhibiting the behavior

when cooperation occurs among individuals of:

• same species—cooperation

• different species—mutualism

Individuals don’t act for good of species (50)

some apparent acts of cooperation are misunderstood

• like when animals sacrifice themselves for good of their species

e.g., “self-sacrificing” and “selfish” alleles

• individuals w/ self-sacrificing alleles would die and not reproduce

• individuals w/ selfish alleles would survive and reproduce

• “selfish” alleles would increase in frequency; “self-sacrificing” alleles would decrease

Geographic distribution (51)

distribution and abundance are two fundamental concepts in ecology

most species identification guides show the range (geographic distribution) of different species:

• abiotic and biotic factors determine range

ranges are dynamic (in constant flux) as abiotic and biotic factors change over time

Population density (51)

the number of individuals per unit area

3 different patterns:

1. random

2. clumped

3. uniform

Population: random (51)

the position of each individual is independent of the others

• may occur when seeds are dispersed by the wind and currents

the average fitness of populations increases in variable environments when dispersal distributes individuals

Population: clumped (51)

organisms associate in social groups (such as schools of fish) or the quality of the habitat is patchy

• individuals associate in social groups for feeding, mating, and/or avoiding predators or resources are patchy

individuals experience higher fitness when they associate in groups

• selection favors individuals that find patchy resources

Population: uniform (51)

if negative interactions occur among individuals, such as competition for space, water, or other resources

• individuals distance themselves from each other as they compete for nutrients, nesting space, or other resources

competition reduces fitness of individuals

• selection favors traits that minimize competition

Metapopulation (51)

a population of populations connected by migration

Demography (51)

the study of factors that determine the size and structure of populations through time

number of individuals present in a population depends on these 4 processes:

1. birth (grow)

2. death (decline)

3. immigration (grow)

4. emigration (decline)

Immigration (51)

when individuals enter a population by moving from another population

Emigration (51)

when individuals leave a population to join another population

Age structure (51)

how many individuals of each age are alive

Generation time (51)

the average time b/w a female’s first offspring and her offspring’s first offspring