Life history strategy
the overall pattern in the timing and nature of life history events are aged across all the individuals in the species
Each species has a range of environmental tolerances that determines its ________ geographic distribution.
The ________geographic distribution of a species is also related to other factors, such as dispersal ability, disturbances, and competition.
The range of conditions over which it occurs.It is a useful tool for predicting the species’ response to climate change.
environmental change results in decreased rates of physiological processes, lowering the potential for survival, growth, or reproduction.
not enough oxygen is delivered to tissues
Adjusting to stress through behavior or physiology. It is a short-term, reversible process, (e.g. acclimatization to high elevations involves higher breathing rates, greater production of red blood cells, and higher pulmonary blood pressure).
natural selection can result in_______ of a population to environmental stress
Ecotypes can eventually become separate species as populations diverge and become reproductively isolated.
The temperature of an organism is determined by __________.
exchanges of energy with the external environment
Some organisms can survive periods of extreme heat or cold by entering a state of_____, in which little or no metabolic activity occurs.
Organisms must either____ temperature change or____ it by physiological, morphological, or behavioral means.
transfer of energy from warmer to cooler molecules
•heat energy is carried by moving water or air.
Latent heat transfer
•water absorbs heat as it changes from a liquid to a gas state.
For terrestrial plants, energy inputs include_____ and______ from surrounding objects, as well as from_____ and _____ if the ground or air is warmer than the plant.
sunlight infrared radiation conductionconvection
Losses of energy include______ of infrared radiation, _______________________________
emission conduction and convection and evapotranspiration
Temperature change in a plant:
SR = Solar radiation IR = Infrared radiation Hconv = Convective heat transfer Hcond = Conductive heat transfer Het = Heat transfer by evapotranspiration
Transpiration rates can be controlled by specialized guard cells surrounding leaf openings called_______.
Variation in ________________ controls the rate of transpiration and thus leaf temperature.
degree of opening and number of stomates
Other mechanisms include ________—hairs on leaf surfaces that reflect solar energy. But hairs also reduce conductive heat loss.
Generating heat internally is an advantage because .....
•Animals can maintain constant internal temperatures near the optimum for metabolic functions under a wide range of external temperatures. •These animals can extend their geographic range.
Rely primarily on internal heat generation—mostly birds and mammals.
Regulate body temperature through energy exchange with the external environment Ectotherms generally have a greater tolerance for variation in body temperature than endotherms.
Heat exchange with the environment depends on the ________ ratio of the body.
A larger _______ allows greater heat exchange, but makes it harder to maintain internal temperature.
As body size increases, _________and large ectotherms are thus improbable.
surface area-to-volume ratio decreases,
Ectotherms in temperate and polar regions must_____ or_____ freezing.
behavior includes seasonal migration to lower latitudes or to microhabitats that are above freezing (e.g., burrows in soil).
to freezing involves minimizing damage associated with ice formation in cells.
Small endotherms with large surface area-to-volume ratio have_____ metabolic rates and require_____ energy and higher feeding rates than large endotherms.
The water balance of an organism is determined by exchanges of ____________ with the external environment.
water and solutes
_____organisms live in an isoosmotic environment, so water balance is not a problem.
_____is the medium in which all biochemical reactions necessary for life occur.
•_______—more saline than an organism’s cells •________—same salinity •_______—less saline
________organisms lose solutes to and gain water from their hypoosmotic environment.
Water flows from a region of high concentration (low solute concentration) to a region of low concentration (high solute concentration).
Energy associated with attractive forces on surfaces of large molecules inside cells or on surfaces of soil particles.
________organisms lose water to the dry atmosphere.
Water flows downhill. The associated energy is gravitational potential (experienced in tall trees).
From an area of higher pressure to lower. The associated energy is pressure (turgor) potential.
(units of pressure, usually megapascals) is the sum of all these energy components:
: A force that impedes water movement (or other substances).
•Cell walls allow development of __________when water moves into a cell, the expanding cell presses against the cell wall.
The____ is the zone of life on Earth
•the_______—Earth’s surface crust and upper mantle and
•the_______—the lowest layer of the atmosphere
are large-scale terrestrial communities shaped by the physical environment, categorized by dominant plant forms and characteristics such as leaf deciduousness or succulence.
Evolution of similar growth forms among distantly related species in response to similar selection pressures.
are graphs of average monthly temperature and precipitation at a location, showing the characteristic seasonal climate pattern.
Between 10°N and 10°S Annual precipitation > 2000 mm No seasonal changes High biomass, high diversity—about 50% of Earth’s species Broadleaved evergreen and deciduous trees
Tropical Seasonal Forests and Savannas
•North and south of the wet tropics •Wet and dry seasons associated with movement of the ITCZ •Shorter trees, deciduous in dry seasons, more grasses and shrubs
•In high pressure zones at 30°N and S •High temperatures, low moisture •Sparse vegetation and animal populations •Low water availability constrains plant abundance and influences form
•Between 30° and 50°N latitude •Warm, moist summers and cold, dry winters •Grasses dominate maintained by frequent fires and large herbivores such as bison
Temperate Shrublands and Woodlands
•Between 30° and 40°N latitude •Evergreen shrubs and trees •Mediterranean-type climates—wet winters and hot, dry summers •Fire is common and helps maintain the biome
Temperate Deciduous Forests
•30° to 50°N, on continental edges with enough rainfall for tree growth •Leaves are deciduous in winter •Oaks, maples, and beeches occur everywhere in this biome •Species diversity lower than tropical rainforests
Temperate Evergreen Forests
•30° to 50°N and S, coastal, continental, and maritime zones •Lower diversity than tropical and deciduous forests •Leaves tend to be acidic, and soils nutrient-poor
(Taiga): •50° to 65°N •Long, severe winters •Permafrost (soil that remains frozen year-round) prevents drainage and results in saturated soils •Trees present are conifers—pines, spruces, larches—and birches
•Above 65° latitude, mostly in the Arctic •Cold temperatures, low precipitation •Short summers with long days •Vegetation is sedges, forbs, grasses, low-growing shrubs, lichens, and mosses •Widespread permafrost
Streams and rivers are_____ (flowing water) systems.
Fast moving water with coarse particles on the stream bed.
Deeper water, with slower flow and finer sediments.
organisms are bottom dwellers and include many kinds of invertebrates. Some feed on detritus (dead organic matter), others are predators. Some live in the hyporheic zone—the substratum below and adjacent to the stream.
The _________________describes changes in biological communities with stream order and channel size.
river continuum concept
Lakes and still waters (_____) occur where depressions in the landscape fill with water.
Open water dominated by plankton (small and microscopic organisms suspended in the water).
are photosynthetic, restricted to the upper layers through which light penetrates (photic zone)
are nonphotosynthetic protists and tiny animals.
near shore, where the photic zone reaches the bottom. Macrophytes occur in this zone.
Ocean water rises and falls in most nearshore zones twice daily. Tides produce unique transition zones between terrestrial and marine environments.
occur where rivers flow into oceans. Salinity varies as fresh water from the river mixes with salt water from the sea.
Shallow coastal wetlands dominated by grasses and rushes.Terrestrial nutrients enhance productivity.Tides produce salinity gradients that result in zones with different plant species.Marshes provide food and protection for fish, crabs, birds, and mammals
dominate some tropical coastal zones. Mangroves are salt-tolerant, evergreen trees and shrubs from 16 different plant families. The roots trap sediments, which build up and modify the shoreline.provide nutrients to other marine ecosystems and habitat for many animals. Several unique animals associated with mangroves include manatees, crab-eating monkeys, fishing cats, and monitor lizards.
Rocky intertidal zones
provide a stable substrate for many organisms.Sessile organisms must cope with wet and dry conditions and changing salinity as the tides rise and fall.Mobile organisms can move into pools at low tide to avoid desiccation.
are not very stable, have little available food, and lots of wave action. But many invertebrates, such as clams, sea worms, and mole crabs, burrow into the sand. Smaller organisms, such as polychaete worms, hydroids, and copepods live on or among the grains of sand.
develop a complex habitat that supports a huge diversity of marine life. Rates of biomass production are some of the highest in the world.
submerged communities of flowering plants in subtidal marine sediments. Algae and animals grow on the plants, and larval stages of many organisms use them for habitat.
“forests,” support a diverse marine community, including sea urchins, lobsters, mussels, abalones, many other seaweeds, and sea otters.
: Open ocean beyond the continental shelves. The photic zone, which supports the highest densities of organisms, extends to about 200 m in depth. Below the photic zone, energy is supplied by falling detritus.
(swimming organisms capable of overcoming ocean currents)—fish, mammals, sea turtles, squid, octopus
Current or short term conditions—temperature, precipitation, humidity, cloud cover.
Energy transfer by movements of air or water currents.
Kinetic energy is transferred by molecules in direct contact with one another.
Sensible heat flux
Energy transfer from warm air immediately above the surface to the cooler atmosphere by convection and conduction.
Latent heat flux
Heat loss due to evaporation.
The atmosphere contains ________ that absorb and reradiate the infrared radiation emitted by Earth. • Water vapor (H2O) • Carbon dioxide (CO2) • Methane (CH4) • Nitrous oxide (N2O)
Warm air is less dense than cool air, and it rises
decreases with altitude, so the rising air expands and cools
Air descends when it cools and forms a high pressure zone at about 30°N and 30°S. Major deserts of the world are at these latitudes.
Large scale circulation patterns resulting from uplift in the tropics.
at the North and South Poles—cold air descends, creating high pressure zones with little precipitation (polar deserts).
exist at mid-latitudes.
These atmospheric circulation cells result in the major climatic zones in each hemisphere—______,_______, and _____ zones.
The winds appear to be deflected due to the rotation of the Earth
Water has a higher_______ than land—it can absorb and store more energy without changing temperature.
occurs where deep ocean water rises to the surface.Upwelling occurs where prevailing winds blow parallel to a coastline. Surface water flows away from the coast and deeper, colder ocean water rises up to replace it. Upwellings influence coastal climates.
Temperature decreases with elevation. Air pressure and density decrease with elevation there are fewer air molecules to absorb infrared radiation. Wind speed also increases at high elevations due to less friction with the ground surface.
Coastal areas have a _________—little daily and seasonal variation in temperature, and high humidity.
Areas in the center of large continents have ________—much greater variation in daily and seasonal temperatures, especially in temperate zones.
North–south trending mountain ranges create a ______________: The windward slope facing the prevailing winds has high precipitation and lush vegetation the leeward slope gets little precipitation.
rain shadow effect
Amount of solar radiation a surface reflects light-colored surfaces have highest albedo.
Water loss through transpiration by plants, plus evaporation from the soil. It transfers energy (as latent heat) and water into the atmosphere, thereby affecting air temperature and moisture.
Intertropical Convergence Zone
Seasonal changes in precipitation result from movement of the (ITCZ), the zone of maximum solar radiation and atmospheric uplift.The ITCZ moves from 23.5°N in June to 23.5°S in December.
Oceans and lakes can become_______—warm surface water on top of colder, denser water results in layers that do not mix.
Oceans and lakes can become_______—warm surface water on top of colder, denser water results in layers that do not mix.
In summer, the warm______ lies over the colder______. The________ is the zone of transition.
epilimnion, hypolimnion, thermocline
El Niño Southern Oscillation
(ENSO), are longer-scale climate variations that occur every 3 to 8 years and last about 18 months.
events are stronger phases of the normal pattern, with high pressure off the coast of South America and low pressure in the western Pacific. They usually follow El Niño, but tend to be less frequent.
North Atlantic Oscillation
a similar atmospheric pressure–ocean current oscillation that affects climate in Europe, northern Asia, and the eastern coast of North America.
Pacific Decadal Oscillation
(PDO) affects climate around the North Pacific.
The glacial–interglacial cycles have been explained by regular changes in the shape of Earth’s orbit and the tilt of its axis
Concentration of dissolved salts in water. Salts are composed of positively and negatively charged ions that disassociate when placed in water. Salts affect the ability of organisms to absorb water. Salts can also be nutrients.
Soils in arid regions become saline when water is brought to the surface by plant roots or irrigation and high rates of evapotranspiration result in salt build-up.
Ability of a solution to act as an acid—a compound that gives up protons (H+) to a solution.
Ability of a solution to act as a base—a compound that takes up H+ or gives up hydroxide ions (OH–).
(low-oxygen) conditions can also promote formation of toxic chemicals (e.g., H2S).O2 levels are important for chemical reactions that determine nutrient availability.
The two aspects of the PDO that are significant for ecology
1.The relationship between climate and organism functioning, growth and reproduction, and population and community processes. 2. The time scale of the PDO is long—20- to 30-year cycles—relative to ENSO.
Experimental groups are compared with a control group that lacks the factor being tested.
the scientific study of interactions between organisms and their environment
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.
scales of study
Spatial scales: •Small—soil microorganisms •Large—atmospheric pollutants Temporal scales: •Short—leaf response to sunlight •Long—how species change over geologic time
A group of individuals of a species that are living and interacting in a particular area
An association of populations of different species in the same area.
Ecological studies often include both the_____ (living) and______ (physical) components of natural systems.
A community of organisms plus their physical environment
Areas with substantial differences, typically including multiple ecosystems
All the world’s ecosystems comprise the ________—all living organisms on Earth plus the environments in which they live.
1. Change in genetic characteristics of a population over time. 2. Descent with modification—organisms gradually accumulate differences from their ancestors.
A characteristic that improves survival or reproduction.
Individuals with certain adaptations tend to survive and reproduce at a higher rate than other individuals
use energy from an external source (e.g., the sun) to produce their own food
Net primary productivity (NPP)
Energy captured by producers minus the amount lost as heat in cellular respiration.
get energy by eating other organisms or their remains.
Energy moves through ecosystems in a single direction only—it cannot be recycled. But nutrients are continuously recycled from the physical environment to organisms and back again
A directional change in climate (such as global warming) that occurs over 30 years or longer.
performing each treatment more than once reduces possibility that results are due to a variable that was not measured or controlled in the study
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.
Evolution can be viewed as.....
genetic change over time or as a process of descent with modification
_______is the genetic makeup of an individual.
Genes can have two or more forms called______
change in allele frequencies (proportions) in a population over time
Evolution can be defined more broadly as......
as descent with modification
Individuals with certain heritable traits survive and reproduce more successfully than other individuals
Observable characteristics that are determined by the genotype, the environment, and interactions between the two
a change in DNA Mutations can result from: 1)copying errors during cell division 2)mechanical damage 3)exposure to chemicals (mutagens) 4)high-energy radiation
produces different genotypes within a population. Offspring have combinations of alleles that differ from those of their parents.
1.Individuals at one phenotypic extreme (e.g., large size) are favored.
Individuals with an intermediate phenotype are favored
Individuals at both phenotypic extremes are favored
occurs when chance events determine which alleles are passed to the next generation. It is significant only for small populations
Genetic drift has four effects on small populations:
1. It acts by chance alone, thus causing allele frequencies to fluctuate at random. Some may disappear, others may reach 100% frequency (fixation). 2. Because some alleles are lost, genetic variation of the population is reduced. 3. Frequency of harmful alleles can increase if the alleles have only mildly deleterious effects. 4. Differences between populations can increase. Chance events may lead to allele fixation in one population and loss from another population.
Alleles move between populations via movement of individuals or gametes. Gene flow has two effects: 1. Populations become more similar. 2. New alleles can be introduced into a population.
______ is the only evolutionary mechanism that consistently causes adaptive evolution
are features of organisms that improve their ability to survive and reproduce. Adaptations include morphological and physiological features such as enzymes that function at high temperatures.
By consistently favoring individuals with certain alleles, natural selection causes ____________—traits that confer advantages tend to increase in frequency over time.
Environments are constantly changing, and there are constraints on evolution
1) Lack of genetic variation 2) Evolutionary history 3) Ecological trade-offs
Lack of genetic variation
If there is no beneficial allele, adaptive evolution at that gene cannot occur
Natural selection works on traits that already exist. Organisms have certain characteristics and lack others because of their ancestry.
The ability to perform one function may reduce the ability to perform another function. Adaptations represent compromises in the abilities of organisms to perform different and sometimes conflicting functions.
Biological Species Concept
Group of organisms whose members have similar characteristics and can interbreed.
The process by which one species splits into two or more species
is a branching diagram that represents the evolutionary history of a group
Increased diversity of the surviving groups. Mass extinctions remove competitor groups, allowing survivors to expand into new habitats or new ways of life.
Reciprocal evolutionary change in interacting species.
leaves isolated patches, which can affect evolutionary processes.
the genetic contribution of an organism's descendants to future generations however, all organisms face constraints that prevent evolution of a perfect life history
life history strategy
the overall pattern in the timing and nature of life history events averaged across all the individuals of a speccies
a single genome may produce different phenotypes under different environmental conditions every trait shows some degree of some plasticity
a single genotype produces discrete types, or morphs, with few or no intermediate form
describe the relative amounts of energy or resources that an organism devotes to different functions
differential growth of body parts that results in a change shape or proportion with size allometry is a very common mechanism of variation within and among species
complex life cycle
one in which there are at least two distinct stages that differ in their habitat, physiology, or morphology.
an abrupt transition in form from the larval to the juvenile stage that is sometimes accompanied by a change of habitat
simple life cycles are referred to this sometimes because development from fertilized eggs to juvenile occurs within the egg prior to hatching and no free-living larval stage occurs
produce only once in a lifetime
have the capacity for multiple bouts of reproduction
the selection for high population growth rates
refers to the section for slower rates of increase, which occurs in populations that are approaching that carrying capacity (K)
are superior in their ability to acquire light minerals water and space
grime classified plants the are adapted to habitats with high levels of disturbance and the low levels of stress as __________.
changes in sex during the course of the life cycle
such as earthworms and soil fungi, consume nonliving organic matter.
Parasites and herbivores
consume live hosts, but do not necessarily kill them.
capture and consume live prey animals.
photosynthetic but obtains nutrients, water, and some of its energy from the host plant (e.g. mistletoe)
have no photosynthetic pigments and get energy from other plants (they are heterotrophs) (e.g. dodder).
Sunlight provides the energy to take up CO2 and synthesize organic compounds (most autotrophs
(chemolithotrophy): Energy from inorganic compounds is used to produce carbohydrates
The electrons are used to generate high-energy___ and_____
Energy in ATP and NADPH is then used to take up CO2 and make carbohydrates
It occurs in both chemosynthetic and photosynthetic organisms.
Photosynthesis has two major steps:
1. Light-driven reactions—light energy is harvested and used to split water and provide electrons to make ATP and NADPH. 2. Carbon reactions—CO2 is fixed in the Calvin cycle, and carbohydrates are synthesized.
C4 photosynthetic pathway
reduces photorespiration and evolved independently several times. Many grass species use this pathway, including corn, sugarcane, and sorghum. It involves biochemical and morphological specialization.
Crassulacean acid metabolism (CAM)
minimizes water loss. CO2 uptake and the Calvin cycle are separated temporally. CAM plants open their stomates at night when it is cooler and humidity is higher and close them during the day.
The energy gain depends on the chemistry of the food and how much effort is needed to find and ingest the food.