Untitled Flashcards Set

Chapter 3

• Combination of all ecosystems on Earth form the Biosphere

  • 20-km thick layer around Earth between the deepest ocean bottom and the highest mountain peak

• When one organism consumes another, not all of the energy in the consumed organism is transferred to the consumer

• Photosynthesis is the process of using solar energy to convert carbon dioxide and water into glucose

  • Glucose is a form of potential energy that can be used by a wide range of organisms 

  • Also produces oxygen as a waste product 

  • Solar energy + 6 H2O + 6 CO2 → C6H12O6 + 6 O2

• Cellular respiration is the process by which cells unlock the energy of chemical compounds 

  • Aerobic respiration is when cells convert glucose and oxygen into energy, CO2, and water 

  • Anaerobic respiration is when cells convert glucose into energy in the absence of oxygen 

  • Does not provide as much energy as aerobic respiration

  • Energy + 6 H2O + 6CO2 ← C6H12O6 + 6 O2

• Producers both produce and consume oxygen 

  •  Generate more oxygen through photosynthesis than they consume through respiration 

  • Overall, producers photosynthesize more than they respire 

  • Net effect is excess of oxygen released into the air and an excess of carbon stored in the tissues of producers 

• Consumers are incapable of performing photosynthesis and must obtain energy by consuming other organisms 

  • Primary Consumers 

    • Herbivores

    • Include a variety of familiar plant and algae eating animals such as zebras, grasshoppers, tadpoles, and zooplankton

  • Secondary Consumers

    • Carnivores

    • Lions, hawks, rattlesnakes

  • Tertiary Consumers

    • Carnivores that eat secondary consumers

    • Bald eagles 

• Successive level of organisms consuming one another are knows as trophic levels

• Sequence of consumption from producers through tertiary consumers is the food chain 

  • Helps us visualize how energy and matter move between trophic levels 

• Food web is a complex model of how energy and matter move through trophic levels 

• Omnivores operate at several trophic levels 

  • Grizzly bears who eat berries and fish 

  • Venus Fly Trap can photosynthesize and digest insects 

• Each trophic level eventually produces dead individuals and waste products 

  • Scavengers

    • Organisms that consume dead animals such as vultures

  • Detritivores

    • Organism such as dung beetles that specialize in breaking down dead tissues and waste products into smaller particles

  • Decomposers

    • Fungi and bacteria that complete the breakdown process by converting organic matter into small elements and molecules that can be recycled back into the system 

• Amount of energy available in an ecosystem determines how much life the ecosystem can support 

• Gross Primary Productivity

  • Measure of the total amount of solar energy that the producers in the system capture via photosynthesis over a given time 

  • GPP does not subtract the energy that is lost when the the producers respire 

  • Measure of how much photosynthesis is occurring over some amount of time 

  • Difficult ot calculate because a plant rarely photosynthesizes and respires simultaneously 

• Net Primary Productivity 

  • Energy captured by producers in an ecosystem minus the energy producers respire 

  • Ranges from 25 to 50 percent of the GPP 

  • Helps measure change in a system 

• Net primary productivity of an ecosystem establishes the rate at which biomass- the total mass of all living matter ina  specific area- is produced over a given amount of time 

• The amount of biomass present in an ecosystem at a particular time is its standing crop 

  • Standing crop measures the amount of energy in a system at a given time, while productivity measures the rate of energy production over a span of time 

• Proportion of energy that can be passed from one trophic level to another is referred to as ecological efficiency 

  • Are fairly low: range from 5 to 20 percent 

  • Total biomass available at a given trophic level leads to only 10 percent being converted into energy at the next higher trophic level

• Trophic pyramid is representation of the distribution of biomass, numbers, of energy among trophic levels

  • Tend to have similar proportions across ecosystems 

  • Most of the energy and biomass are found at the procure level and they commonly decrease as we move up the pyramid

Chapter 6 

• Community ecology is the study of interactions among species

• Symbiotic relationships 

  • Relationship between two species that  are living in close association with each other 

  • Include competition, predation, parasitism, and herbivory

Negative interactions

• Competition

  • Struggle of individuals to obtain a shared limiting resource 

  • Competitive exclusion principle

    • Two species competing for the same limiting resource cannot coexist 

  • Leads to resource partitioning in which two species divide a resource based on differences in their behavior or morphology 

  • Temporal resource partitioning 

    • Process in which two species utilize the same resource but at different times 

  • Spacial resource partitioning

    • Two species reduce competition by using different habitats 

  • Morphological Resource partitioning

    • Evolution of differences in body size or shape 

• Predation 

  • Interaction in which one animal typically kills and consumes the other animal 

  • Parasitoids are animals that lay eggs inside other organisms

  • Defenses include behavioral, morphological, and chemical 

• Parasitism 

  • Interaction in which one organism lives on or is in another organism 

  • Single parasite rarely causes the death of its host 

  • Pathogens are parasites that cause diseases in their hosts 

• Herbivory

  • Interaction in which an animal consumes a producer 

  • Typically only eat a portion of a producer without killing it  

Positive Interactions

• Mutualism

  • Interaction between two species that increases the chances of survival or reproduction of both species 

  • Under such conditions, natural selection will favor individuals that no longer engage in the mutualistic interaction

• Commensalisms

  • Relationship between species in which one species benefits and the other species is neither harmed nor helped 

  • Very common in nature 

• Keystone species is a species that is not very abundant but has a large effect on an ecological community 

  • Beavers

  • Without the keystone in place, the arch would fall apart

• Ecosystem engineer is a keystone species that creates or maintains habitat for other species 

  • Beavers and alligators 

Chapter 4

• Terrestrial Biomes are geographic regions categorized by a particular combination of average annual temperature, annual precipitation, and distinctive plant growth forms on land

• Aquatic Biomes are aquatic regions characterized by a particular combination of salinity, depth, and water flow 

• Tundra Biome

  • Cold and treeless with low growing vegetation 

  • Growing season is usually about 4 months during the summer, when the polar region is titled toward the Sun and the days are very long

    • During this time, the upper layer of soil thaws, creating pools of standing water 

  • Permafrost is an impermeable, permanently frozen layer of soil

    • Prevents water from draining and roots from penetrating 

  • Permafrost and cold temperatures prevent deep rooted plants from growing 

  • Little precipitation, but enough to support plant growth 

  • Contains small woody shrubs, mosses, heaths, lichens

  • Dead plants and animals decompose very slowly 

• Boreal forest Biome

  • Forest biome made up primarily of coniferous evergreen trees that can tolerate cold winters and short growing seasons

  • Sometimes called Taiga 

  • Has a very cold climate and plant growth is more constrained by temperature than by precipitation 

  • Soil is covered in a thick layer of organic material, but poor in nutrients 

  • Some deciduous trees such as birch, maple, and aspen can be found 

  • Needles of coniferous trees can tolerate freezing conditions

  • Serve as an important source for paper,pulp, and building materials 

• Temperate Rainforest Biome 

  • Coastal biome typified by moderate temperatures and high precipitation

  • Winters are rainy and summers are foggy

  • Supports growth of very large trees

  • Slow decomposition, but not as slow as the tundra or Boreal forest

• Temperate Seasonal Forest

  • Biome with warm summers and cold winters with over 1 m of precipitation annually 

  • Dominated by deciduous trees

  • Rapid decomposition 

  • Have high soil fertility and support plant productivity 

  • Said to be one of the first biomes to be converted to agriculture on a large scale 

• Woodland/Shrubland Biome 

  • Biome characterized by hot, dry summers and mild, rainy winters

  • 12 month growing season, but plant growth is constrained by high temperatures and low precipitation in the summer and by cool temperatures and high precipitation in the winter

  • Ideal conditions for growing grapes to make wine 

  • Favor occurrence of wildfires 

  • Drought resistant shrubs such as Yucca, scrub, oak, and sagebrush 

  • Soil is low in nutrients due to leaching by the winter rains 

  • Also called chaparral 

• Temperate Grassland/Cold Desert

  • Biome characterized by cold, harsh winters, and hot, dry summers

  • Plant growth is similar to Woodland 

  • Fires are common, as the dry and frequently windy conditions fan flames ignited by lightning 

  • Cold deserts have even sparser vegetation than shortgrass prairies

  • Very cold winters and do not support characteristic plan growth of hot deserts such as cacti and euphorbs 

• Tropical Rainforest

  • Warm and wet biome found between 20 degrees N and 20 degrees S of the equator, with little seasonal temperature variation and high precipitation 

  • High productivity and rapid decomposition 

  • High rate of decomposition causes the soils to lose their fertility quickly , so little undecomposed organic matter(humus)

  • Contain mot biodiversitY 

  • Main threat is deforestation 

• Tropical Seasonal Forest/ Savanna

  • Biome marked by warm temperatures and distinct wet and dry seasons

  • Tropical deciduous forest

  • Common plants include acacia and baobab trees

  • Grazing and fire discourage growth of many smaller woody plants and keep the savanna landscape open 

  • Presence of trees and warmer average annual temperature differentiate savanna from grassland 

  • Promotes decomposition, but low precipitation constrains plants from using soil nutrients that are released

  • Soils are fertile 

• Subtropical Desert

  • Biome prevailing at approximately 30 degrees N and S with hot temperatures, extremely dry conditions, and sparse vegetation 

  • Also known as hot deserts

  • Contains Cacti, Euphorbs, and succulent plants

  • When there is rainfall, growth is rapid 

• Aquatic Biomes are not categorized by temperature 

• Freshwater Biomes include streams, rivers, lakes and wetlands

• Saltwater Biomes include shallow marine areas such as estuaries and coral reefs, also the ocean

• Streams and Rivers

  • Characterized by flowing fresh water that may originate from underground springs or as runoff from rain or melting snow

  • Streams are typically narrow and carry relatively small amounts of water

  • Rivers are typically wider and carry larger amounts of water 

  • Fast moving streams and rivers typically have stretches of turbulent water called rapids, where water and air are mixed together

  • The mixing allows large amounts of oxygen to enter the water and supports fish fish species

  • Slower moving rivers experience less mixing of air and water which favor species that can handle low-oxygen conditions

    • Catfish

• Lakes and Ponds

  • Contain standing water, at least some of which is too deep to support emergent vegetation 

  • Lakes are larger than ponds

  • Littoral zone is the shallow zone of soil and water in lakes and ponds where most algae and emergent plants grow

    • Most photosynthesis occurs in this zone

  • Limnetic zone is a zone of open water in lakes and ponds

    • Contains phytoplankton 

    • Extends as deep as sunlight penetrates

  • Profundal zone is region of water where sunlight does nor each, below the limnetic zone in very deep lakes 

    • Producers cannot survive here

  • Benthic zone is the muddy bottom of a lake,pond, or ocean 

  • Lakes are classified by their level of primary productivity 

    • Low productivity due to low amounts of nutrients such as phosphorous and nitrogen in the water are called oligotrophic 

    • Moderate level of productivity is mesotrophic

    • High level of productivity is Eutrophic 

• Freshwater Wetlands

  • Aquatic biomes that are submerged or saturated by water for at least part of each year, but shallow enough to support emergent vegetation 

  • Support species of plants that are specialized to live in submerged or saturated oils

  • Include swamps, marshes, and bogs

  • Swamps are wetlands that contain emergent tres

  • Marshes are wetlands that contain primarily non woody vegetation

  • Bogs are very acidic

  • Wetlands can take in large amounts of rainwater and release it slowly into the groundwater or into nearby streams

• Marine biomes contain salt water and can be categorized as salt marshes, mangrove swamps, intertidal zones, coral reefs and the open ocean. 

• Salt Marshes

  • Marsh containing nonwoody emergent vegetation, found along the coast in temperate climates

  • Found within an estuary which is an area along the coast where the fresh water of a river mixes with salt water from the ocean

  •  Habitat for spawning fish and shellfish 

• Mangrove swamps

  • Swamp that occurs along tropical and subtropical coasts, and contains salt-tolerant trees with roots submerged in water

  • Mangrove trees are salt tolerant 

• Intertidal Zones

  • Narrow band of coastline between the levels of high tide and low tide

  • Range from steep rocky areas to broad sloping mudflats 

• Coral Reefs

  • Most diverse marine biome on Earth, found in warm, shallow waters beyond the shoreline

  • Corals are tiny animals that secrete a layer of limestone to form an external skeleton 

  • Corals live in water that is relatively poor in nutrients and food 

  • Corals die and their skeletons accumulate to become a coral reef 

  • Coral Bleaching is a phenomenon in which algae inside corals die, causing to turn white

• Open Ocean

  • Deep ocean water, located away from the shoreline where sunlight can no longer reach the ocean bottom

  • Photic zone is the upper layer of the ocean water in the ocean that receives enough sunlight fir photosynthesis 

  • Chemosynthesis is process used by some bacteria in the ocean to generate energy with methane and hydrogen sulfide

• Biogeochemical Cycle

  • Movements of matter within and between ecosystems 

  • Components that contain matter(air, water, and organisms) are referred to as pools

  • Processes that move matter between pools are knows as flows

• The movement of water through the biosphere is known as the Hydrologic cycle

  • The release of water from leaves during photosynthesis is transpiration

  • Combined amount of evaporation and transpiration is called evapotranspiration

  • Helps move elements that are dissolved in the water

• Harvesting trees can reduce evapotranspiration

  • Runoff and percolation can increase

  • Leads to erosion and flooding

• Carbon makes up 20% of an organisms body weight68

• Carbon Cycle

  • Movement of carbon around the biosphere

  • Photosynthesis, respiration, exchange, sedimentation, burial, extinction and combustion

  • The amount of carbon released from the ocean into the atmosphere roughly equals the amount of atmospheric CO2 that diffuses into ocean water

  • Portion of Carbon dioxide dissolved into the ocean combined with calcium ions to form calcium carbonate

    • Compound which can precipitate out of the water and form limestone and dolomite rock via sedimentation and burial 

  • Although sedimentation is a long process, small amounts of calcium carbonate sediment formed each year have accumulated over millions of years to form the largest carbon pool in the slow part of the carbon cycle 

  • Extraction is a relatively recent phenomenon 

  • Extraction AND combustion alter the Carbon Cycle

  • Combustion, Respiration, and Decomposition all cause organic molecules to be broken down to produce CO2, water, and energy 

    • However, respiration and decomposition are biotic processes, whereas combustion is an abiotic process

  • Exchange of carbon between the Earth’s surface and atmosphere is in a steady state

  • Excess CO2 in the atmosphere acts to increase the retention of heat energy in the biosphere

    • Results are global warming 

• Nitrogen Cycle

  • Macronutrients

    • Six key elements needed by organisms in a relatively large amount

      • Nitrogen, phosphorous, calcium, magnesium, and sulfur

  • Nitrogen is considered a limiting nutrient for producers

    • Nutrient required for the growth of an organism but available in a lower quantity than other nutrients 

  • Nitrogen Cycle is the movement of nitrogen around the biosphere

  • Includes: Nitrogen Fixation, Nitrification, Assimilation, Mineralization, and denitrification 

  • Nitrogen Fixation

    • Process that converts nitrogen gas in the atmosphere(N2) into forms of nitrogen that producers can use

    • Can office through biotic or abiotic processes

    • Biotic Fixation

      • Cyanobacteria can convert N2 gas into ammonia (NH3), which is rapidly converted to ammonium (NH4+), a form that producers can use 

    • Abiotic fixation

      • N2 can be fixed in the atmosphere by combustion processes, which then convert N2 into Nitrate(NO3-)

      • Nitrate is carried to Earth’s surface via precipitation 

  • Nitrification

    • Conversion of ammonium into nitrite, then into nitrate 

    • Conducted by specialized species of bacteria

    • Nitrite is not used by most producers, but nitrate is

  • Assimilation

    • Process by which producers incorporate elements into their tissues

    • Usually when primary consumers feed on producers, producers nitrogen is assimilated into the tissue of the consumers, while rest is eliminated as waste products

  • Mineralization

    • Process by which fungal and bacterial decomposers break down the organic matter found in dead bodies and waste products and convert it into inorganic compounds 

    • Sometimes called ammonification

      • Process by which fungal and bacterial decomposers break down the organic nitrogen found in dead bodes and waste products and convert it into inorganic ammonium 

  • Denitrification

    • Final step which involves the conversion of nitrate in a series of steps into the gases nitrous oxide(n2o),and eventually, nitrogen has which is emitted into the atmosphere 

    • Conducted by bacteria that live under anaerobic conditions 

• The Phosphorus Cycle

  • Movement of phosphorous in the biosphere

  • Primarily operates between land and water; There is no gas phase 

  • Phosphorous rarely changes form: Typically found in the form Phosphate 

  • Producers on land and in the water take up inorganic phosphate and assimilate the phosphorous into their tissues as organic phosphorous 

  • Abiotic process involves movement between water and land 

    • Phosphorous is not soluble in water, so much of it precipitates out of solution in the form of phosphate-laden sediments

    • Over time, geologic forces can lift these ocean layers and they become mountains

    • The phosphate rocks in the mountain are slowly weathered, brining the phosphorous to terrestrial habitats

  • Limiting nutrient in aquatic habitats 

  • Increased phosphate in aquatic ecosystems can cause algal blooms 

    • Water will become hypoxic: lox in oxygen

  • Dead zone os when oxygen concentrations become so low that it kills other aquatic animals 

• The Sulfur Cycle

  • Producers absorb sulfur through their roots in the form of sulfate ions

  • Volcanic eruptions are natural source of atmospheric sulfur int he form of sulfur dioxide 

  • SO2(atmospheric sulfur) turns into sulfuric acid when it mixes with water

  • Carried back to earth when it rains or snow 

Chapter 5

• Number of species in any given place is the most common measure of biodiversity, but can be a challenge

• Species richness is the number of species in a given area

  • Used to give an approximate sense of the biodiversity of a particular place

• Species evenness is the relative proportion of individuals within the different species in a given area 

  • Tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundances

  • Is high is ecosystem’s species are all represented by similar numbers of individuals 

  • Is low if one species is represented by many individuals whereas other species are represented by only a few individuals 

• Phylogeny is the branching pattern of evolutionary relationships 

• More similar the traits of two species, the more closely related they are

• Range of tolerance 

  • The limits to the abiotic conditions that a species can tolerate 

  • Ex; extreme temperatures, humidity, salinity, pH

• Fundamental niche is the suite of abiotic conditions under which a species can survive, grow, and reproduce 

  • Establishes abiotic limits for the persistence of a species 

  • However, biotic factors can further limit the locations where a species can live 

    • Presence of competitors, predators, and diseases 

  • Biotic factors narrow the fundamental niche a species actually uses 

• Realized niche is the range of abiotic and biotic conditions under which a species actually lives 

• Determining what contributes to the realized niche, helps understand the distribution, areas of the world in which species live, of a species

• Niche Generalist is a species that can live under a wide range of abiotic or biotic conditions 

  • Can persist in changing conditions 

• Niche Specialist is a species that is specialized to live in a specific habitat or to feed on a small group of species 

  • Persist quite well when conditions are constant, but vulnerable to extinction 

• Average life span of a species is about 1 million to 10 million years 

  • 99% if the species that have ever lived on Earth are extinct 

• The fossil record has noted 5 periods of global mass extinctions 

• Greatest mass extinction took place 251 million years ago

  • Roughly 90% of marine species and 70% of land vertebrates went extinct 

• Dinosaurs went extinct at the end of the cretaceous period(65 million years ago) 

  • Caused by a meteorite and resulted in a large dust cloud, halting photosynthesis 

• A 6th mass extinction is currently in place 

  • 800 extinctions over the past 400 years 

• Earth’s biodiversity is the product of evolution

  • Microevolution is evolution below the species level

  • Macroevolution is evolution that gives rise to new species, genera, families, classes, or phyla 

    • Speciation is restricted to the evolution of new species 

• Genes are physical locations on chromosomes within each cell of an organism 

• Complete set of genes in an individual is called its genotype 

• An individual’s phenotype is the actual set of trays expressed in that individual 

  • Color of your eyes 

• Most phenotypes are the result of an individual’s environment, a well its genotype 

• Environmental factors can cause mutations 

  • UV radiation 

• Recombination is the process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division 

  • Does not create new gene, but brings together new combinations of alleles on a chromosome 

• Evolution by artificial selection 

  • The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind 

• Evolution by natural selection 

  • The process in which the environment determines which individuals survive and reproduce 

• Key ideas of Darwin’s theory 

  • Individuals produce an excess of offspring 

  • Not all offspring can survive 

  • Individuals differ in their traits 

  • Difference in traits can be passed on from parents to offspring 

  • Differences in traits are associated with differences in the ability to survive and reproduce 

• Natural selection factors any combination of traits that improves an individual’s fitness

  • Ability to survive and reproduce 

  • Traits that improve an individual’s fitness is called an adaptation 

• Evolution can also occur by 5 random processes: 

  • Mutation 

  • Gene flow 

    • Process by which individuals move from one population to anther and thereby alter the genetic composition of both populations 

    • Can be helpful to bringing genetic variation into a population 

  • Genetic drift 

    • Change in the genetic composition of a population over time as a result of random mating 

  • Bottleneck effect 

    • Reduction in the genetic diversity of a population caused by a reduction in its size 

    • Can cause extinction 

  • Founder effect 

    • Change in the genetic composition of a population as a result of descending from a small number of colonizing individuals 

• Geographic isolation 

  • Physical separation of a group from individuals from others of the same species 

• Allopatric speciation 

  • Process of speciation that occurs with geographic isolation 

• Reproductive isolation 

  • Result of two populations within a species evolving separately to the point that they can no longer interbreed and produce viable offspring 

• Sympatric speciation 

  • Evolution of one species into two, without geographic isolation 

  • Usually happens through process called polyploidy 

    • Number of chromosomes is increased 

• Evolution occurs more faster in genetically modified organisms 

  • Organism produced by copying genes from a species with a desirable trait and inserting them into another species 

Chapter 3

• Disturbance 

  • An event caused by physical,chemical, or biological agents, resulting in changes in population size or community competition 

    • Tsunamis, tornadoes, hurricanes, ice storms, etc

  • Can be caused due to anthropogenic causes

    • Human settlements, agriculture, air pollution, etc.

• Not every ecosystem disturbance is a disaster 

  • Although the population of a species might  be diminished, the net primary productivity of all producers in an ecosystem may stay the same

• Resistance of an ecosystem is a measure of how much disturbance can affect flows of energy and matter

  • When a disturbance influences populations, but has no effect on the overall flow of energy and matter; high resistance 

• Resilience is the rate at which an ecosystem returns to its original state after a disturbance 

  • Depends on specific interactions of the biogeochemical and hydrologic cycles 

• Restoration ecology is the study and implementation of restoring damaged ecosystems 

  • Restoration ecologists are currently working on two main projects: Florida everglades and Chesapeake bay 

• Scientists commonly conduct studies in a watershed

  • All land in a given landscape that drains into a particular stream,river, or wetland

• Intermediate disturbance hypothesis 

  • Hypothesis that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance labels 

  • Highest levels of diversity can occur when ecosystems experience an intermediate frequency of disturbance 

Chapter 6

• Ecological succession is the predicable replacement of one group of species by another group of species over time 

• Primary successions is ecological succession occurring on surfaces that are initially devoid of soil 

• Secondary succession is the succession of plant life that occurs in areas that have been disturbed but have not lost their soil 

• Pioneer species can colonize new areas rapidly and grow well in full sunshine 

• Climax community is described as the final stage of succession 

• In a biome, the number and types of species are determined by 3 factors 

  • Latitude 

    • As we move from the equator toward the north pole, the number of species declines 

  • Time

    • The longer a habitat exists the more colonization, speciation, and extinction can occur in that habitat 

  • Habitat size and distance from a source of species

    • Factors are basic for the theory of island biogeography 

      • Demonstrates the dual importance of habitat size and distance in determining species richness

    • Large habitats contain more species 

      • 1. Dispersing species are more likely to find larger habitats 

      • 2. Larger habitats can support more species 

      • 3. Larger habitats contain a wider range environmental conditions 

    • Distance matters because while many species can disperse short distances, only a few can disperse long distances

• Population 

  • Individuals that belong to the same species and lube un a given area at a particular time 

• Community 

  • All the populations of organisms within a given area 

• Individual -> Population -> Community -> Ecosystem -> Biosphere 

• Population density 

  • Number of individuals per unit area at a given time 

  • Helps scientists determine whether a species is rare or abundant 

• Sex ratio is the ratio of males to females in a population 

• Age structure is the description of how many individuals fit into a particular age category in a population 

• Limiting resource is a resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size 

• Density-dependent factor influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population 

• Density-independent factors have the same effect on an individual’s probability of survival and amount of reproduction at any population size 

• Population growth rate is the number of offspring an individual can produce in a given time minutes the deaths of the individual or its offspring during the same period 

• Intrinsic growth rate is the max potential for growth of a population under ideal conditions with unlimited resources 

• Overshoot is when a population becomes larger than the environment’s carrying capacity 

• Die-off is a rapid decline in population due to death 

• K-selected species is a species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity 

  • Large organisms, produce few offspring 

  • Elephants

• r-selected species 

  • Has high intrinsic growth rate, which often leads to population overshoots and die-offs

• Survivorship curve 

  • Graph that represents the distinct patterns of species survival as a function of age 

• Type I survivorship curve 

  • Pattern of survival over time in which there is a high survival rate throughout most of the life span, but then individuals start to die in large numbers as they approach old age 

• Type II survivorship curve 

  • A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span 

• Type III survivorship core 

  • Pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood 

• Corridor is a strip of natural habitat that connect populations 

• Metapopulation is a group of spatially distinct populations that are connected by occasional movements of individuals between them 

• Inbreeding depressions is when individuals with similar genotypes-relatives- breed with each other and produce offspring that have an impaired ability to survive and reproduce 

Chapter 7

• Deaths and births were stable and relatively equal in numbers a couple hundred years ago 

  • Changes 400 years ago when agricultural output increased and sanitation improved 

• The global human population has grown more rapidly in the last 400 years that at any other time in history 

• Humans can alter Earth’s carrying capacity by employing creativity- one of the fundamental ways in which humans differ from most other species on Earth. 

• Inputs in a human population include both births and immigration 

• Outputs in a human population include both deaths and emigration 

• When inputs are greater than outputs, the growth rate is positive

• Crude Birth Rate

  • Number of births per 1000 individuals per year 

• Crude Death Rate

  • Number of deaths per 1000 individuals per year 

• Global population growth rate in percent= (CBR-CDR)/10

• National population % growth rate= [(CBR + immigration) - (CDR + emigration)]/10

• Doubling time is the number of years it takes a population to double 

  • Gives us better sense of magnitude of the change of a population

  • Can never determine with certainty 

• Doubling time(year)= 70/growth rate(expressed in %)

• Total fertility rate is the estimate of the average number of children that each woman in a population will bear throughout her childbearing years

• Replacement-level fertility 

  • Total fertility rate required to offset the average number of deaths in a population in order to maintain the current population size

  • Typically just over 2 children 

  • Number of children required to replace parents 

• Developed countries have a TFR of about 2

• Developing countries have a TFR of greater than 2

  • Mortality tends to br higher 

• Life expectancy is often reported in three different ways 

  • 1. For overall population of a country 

  • 2. For males only 

  • 3. For females only 

• Infectious diseases are the second biggest killer worldwide after heart disease 

• Migration does not affect the total number of people on the planet 

• Population momentum is continues population growth after growth reduction measures have been implemented 

• The Theory of demographic transition

  • The theory that as a country moves from a subsistence economy to industrialization and increased affluence it undergoes a predictable shift in population growth 

• Phase 1: Slow Population growth

  • High birth rates and High death rates offset one another

  • CBR=CDR

  • Short life expectancies

  • Occurs in countries which are not modernized

• Phase 2: Rapid Population Growth

  • Death rates decline as birth rates remain high 

  • Imbalance; Births outnumber deaths

  • Economies cleanliness and access to food improves

• Phase 3: Stable population growth

  • Economy and education improve 

  • CBR begins to fall 

  • People are affluent and do not want financial burden

• Phase 4: Declining population growth

  • CBR is below the CDR 

  • Fewer young people

• IPAT Equation is used to estimate the impact od the human lifestyle on the environment: impact= population x affluence x technology 

• As GDP increases, country will be able to access more fossil fuels 

• GDP is made up of four types of economic activity

  • Consumer spending

  • Investments 

  • Government spending

  • Exports minus imports

• Two commonly overused local resources are the land and woody biomass front trees and plants