Biology II Final Exam Study Guide

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What is natural selection?
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Terms in this set (87)
What is natural selection?
the process whereby organisms better adapted to their environment tend to survive and produce more offspring

Natural selection: dark rock environment --> light grey beetles are spotted and eaten by birds more often than dark ones
What is a mutation?
any change in the DNA sequence

mutations generate genetic variation because it is changing the sequences of DNA

As a result of mutation, different forms of a gene known as alleles may exist at a particular chromosomal locus and the gene pools of nearly all populations contain variation for many traits
What is gene flow?
movement of alleles from one population to another

same species different populations and have alleles and genes flowing from one population to another
What is genetic drift?
due to chance events, when you eliminate alleles

Bottlenecks: when populations go through environmental events that only a small number of individuals survive

The founder effect can occur if a small number of individuals colonize a new area
What is nonrandom mating?
Nonrandom mating:

assortative mating: preference for similar genotypes or phenotypes

disassortative mating: preference for different genotypes or phenotypes
The Hardy-Weinberg principle
If a population is not evolving and plug in the frequencies and it will come out to be 1

Conditions for a population to be the equilibrium:
No selection, no mutation, no migration, large population, and random mating
What are phylogenetic trees?
-A diagram showing evolutionary relationships among organisms

-Phylogenetic Trees are a diagrammatic reconstruction of that history

-They are used to depict the evolutionary history of species, populations, and genes
What are the components of a phylogenetic tree
-Node: the split that occurs when the ancestorial lineage divides
-These splits can represent events such as speciation, a gene duplication, or a transmission
-The common ancestor of all the organisms in the tree forms the root of the tree
-Flows left (earliest) to right (most recent)
-Any group of species that we designate with a name is a taxon (taxa plural)
-Any taxon that consists of all the evolutionary descendants of a common ancestor is called a clade --Two species that are each other's closest relatives are called sister species
-Two clades that are each other's closest relatives are sister clades
Image: What are the components of a phylogenetic tree
What are homoplasies?
Similar traits generated by convergent evolution and evolutionary reversals
Synapomorphies
Homologous characteristics that are shared with descendants

Shared, derived traits
Homologous vs. AnalogousHomologous: After a certain point of a node all the resulting lineages sharing that trait Analogous: specific trait which pops up as a new trait in different lineagesconvergent evolutionAnalogous traits that evolve independently Shared environments can shape both species even if they aren't in the same groupdivergent evolutionwhen two or more species sharing a common ancestor become more different over time Species diverge form a common ancestorWhat is speciation?Formation of new speciesAllopatric speciationAllopatric speciation: when the speciation event that causes a divergence between an ancestorial species into two new species is triggered or caused by a geographical isolation. Example: Kaibab squirrel was separated from a common ancestor squirrel. This geographical isolation (a giant canyon) cut off gene flow between species and the Kaibab squirrel evolved on its own (phenotypic changes)sympatric speciationSympatric Speciation: when you still get an ancestorial species splitting into two new species but there are no geographical isolation; there is just reproductive isolation that comes about in a population that is basically continuous geographically. Example: polypleidy event (duplicated genome) so if the normal plant has two copies of the genome then the polyploid will have 4n copies of chromosomes and causes speciation because they are isolated reproductively from the normal individuals. Can only mate with polypoid individuals.History of the EarthContinental Drift: Plates (oceanic and continental) Large amount of radiation from the heat in the mantle which creates currents and causes these plates to move around which is continental drift When the plates hit each other (oceanic plate hits a continental plate) the oceanic plate will cause subduction and the continental plate goes up and can make mountains and volcanoes This can isolate species and cause speciation Volcanoes can create havoc for the environment Climate Change: Sea level, meteors, volcanoes When ocean level goes down you can get mass extinction events Because the shallow ocean areas dry up and those species go extinct Volcanic Activity: Massive volcanic events causes sulfate gas at elevated compositions and can change the temp bc it blocks the sun Correlate these events with changes in the earths temp Extraterrestrial events: Meteor that crashed into the planet and caused extinction of the dinosaurs Caused catastrophes: tsunamis, volcanos, change in temperature Oxygen concentration First life: O2 was rare First photosynthetic cyanobacteria First aerobic bacteria First eukaryotes First multicellular eukaryotes First chordates Invasion of land Giant flying insects First flowering plantswhat were the different eras of Earth?Precambrian Era: First life appears on earth Most is small and marine Multicellular life limited for most of era by temperature and atmosphere constraints Snowball earth Paleozoic Era: Life rapidly expanded as oxygen and temperatures became more favorable Multiple mass extinctions occur due to environmental and geological changes 60-80% of species extinct Mesozoic Era: Pangea slowly breaks apart Three periods are ended by mass extinctions due to meteorite impacts Cenozoic Era: Continental movement is slowly approaching current locations Divergence of hominoids leads to species Homo sapiensCompare/contrast: Bacteria, Archaea, EukaryotesBacteria Similarities: Cell membranes Ribosomes (70s) Metabolic pathways (conservative, Semi conservative DNA replication) Differences: (semiconservative) Follow central dogma Peptidoglycan in cell wall Membrane in lipids is ester-linked unbranched Initiator tRNA: formyl methionine Archaea Similarities: Cell membranes Ribosomes (70s) Metabolic pathways (conservative Semi conservative DNA replication Differences: (semiconservative) Follow central dogma Membrane in lipids is ester-linked branched Initiator tRNA: methionine Eukaryotes Similarities: Cell membranes Ribosomes (larger in eukaryotes) (80s) Metabolic pathways (conservative) Semi conservative DNA Differences: replication (semiconservative) Follow central dogma Can be uni- or multi- cellular Divide by mitosis Linear DNA (multiple) Nucleus Contain membrane-enclosed organelles Membrane in lipids is ester-linked unbranched Initiator tRNA: methionineCompare/contrast virusesViruses are not living They infect all forms of life Viruses are abundant and diverse 6 different typesCompare/contrast Protists vs Non-ProtistsWhat are protists? All eukaryotes that are not plants, animals, or fungi Non-protists are... plants, animals, and fungiNon-vascular vs Vascular Plants(Vascular) Land plants that make up 7 out of the 10 major groups -Possess well developed vascular systems that transport materials throughout the plant body -Possess fluid conducting cells called tracheids Vascular plant adaptations: Heterospory appeared among the vascular plants Seedless vascular plants are most similar to their ancestors, the gametophyte and the sporophyte are independent and both are photosynthetic Homosporous: spores develop into a single type of gametophyte that bears both female and male reproductive organs Has antheridium and archegonium Non-vascular land plants are the liverworts, mosses, and hornworts -Lack leaves, stems, and roots Live on soil or on vascular plants, bare rock, dead and fallen trees and even on buildings -This mutualism probably facilitated the absorption of water and minerals, especially phosphorous, from the first soils -Grow in dense mats in moist habitats -Known as the Bryophytes (non-vascular plants) -Live in moist environments -Lack transportation structures so tend to be low and small -Lack typical structures (roots, leaves, stems) -All of them go through alternation of generations -Gametophyte (leafy green part): dominant life stage -Photosynthetic part -Produces gametes (antheridia houses sperm; archegonia houses egg) -Sperm released out into water b/c sperm are flagellated and swims to egg in archegonia and fertilize egg (retain in parental tissue and goes through mitosis) grows up to sporophyte and will die after its done with its job Inside sporangia goes through meiosis and produce n spores and are dispersed, germinate, and grow through mitosis The sporophytes of nonvascular land plants are dependent on the gametophytes In nonvascular plants the green structure that is visible is the gametophyte Photosynthetic and nutritionally independent The sporophyte is nutritionally dependent on the gametophyte and stays attached to it Gametes form within specialized sex organs called gametangia The archegonium is a multicellular, flask shaped female sex organ that produces a single egg The antheridium is a male sex organ in which sperm each bearing two flagella are produced in large numbersGymnosperms vs AngiospermsGymnosperms: Seed plants Do not form flowers or fruits Have ovules, tracheids, and xylem Pollination -Heterosporous: a system with two distinct types of spore -Megaspore develops into a specifically female gametophyte (megagametophyte) that produces only eggs -Microspore is smaller and develops into a male gametophyte (microgametophyte) that produces only sperm -The sporophyte produces megaspores in small numbers in megasporangia and microspores in large numbers in microsporangia -Heterosporous allowed for the production of many small microspores that are easily transported from plant to plant 0 -Results in the production of a few large megaspores in large megasporangia providing nutrition and protection for the embryo Angiosperms: Flowering plants The flowering structure is the sexual structure Ovules and seeds are encased in a carpel Carpels prevent self-fertilization Vessel elements allow for easy transport of water Fiber helps with the plant body structure Pollination -Homosporous: spores develop into a single type of gametophyte that bears both female and male reproductive organs -The female structures of the flower consist of a stigma, style, ovary, and ovules -The male structures are the anther and filament -Both are part of the whole flowerMonoblast, Diploblast, and TriploblastMonoblastic: one cell layer tissue type Diploblastic: animals have two cell layers -outer ectoderm -inner endoderm Triploblastic: three cell layers -outer ectoderm -middle mesoderm -inner endodermAcoelomates vs CoelomatesThe body plans of triploblastic animals can be divided into 3 types: Acoelomate animals lack an enclosed, fluid-filled body cavity. Instead the space between the gut and the muscular body wall is filled with masses of cells called mesenchyme and move by beating cilia Ex. Flatworms Coelomate animals have a body cavity, the coelom the develops within the mesoderm. It is lined with a layer of muscular tissue called the peritoneum, which also surrounds the internal organs. The coelom is enclosed on both the inside and the outside by mesoderm. Ex. EarthwormProtostome vs DeuterostomeProtostomes They are all bilaterally symmetrical animals whose bodies exhibit two major derived traits: An anterior brain that surrounds the entrance to the digestive tract A ventral nervous system consisting of paired or fused longitudinal nerve cords In two of the most prominent protostome groups the coelom has been highly modified: Arthropods lost the ancestral condition of the coelom over the course of evolution. Their internal body cavity has become a hemocoel or blood chamber in which fluid from an open circulatory system bathes the internal organs before returning to blood vessels Most mollusks have an open circulatory system with some of the attributes of the hemocoel but they retain vestiges of an enclosed coelom around their major organs. Protostomes can be divided into two major clades based on DNA analysis: Ecdysozoans and Lophotrochozoans Deuterostomes Two major pieces of evidence that indicate deuterostomes share a common ancestor not shared with protostomes: Deuterostomes share a pattern of early development in which the mouth forms at the opposite end of the embryo from the blastopore, and the blastopore develops into the anus (this is opposed to the protostomes in which the blastopore becomes the mouth) Recent phylogenetic analyses of the DNA sequences of many different genes offer strong support for the shared evolutionary relationships of deuterostomes Include many large animals (including humans) Three major clades of living deuterostomes: Echinoderms: sea stars, sea urchins, and their relatives Hemichordates: acorn worms and pterobranches Chordates: tunicates, lancelets, and vertebrates All are triploblastic and coelomateAquatic vs Land VertebratesAquatic vertebrate needs a strong axial skeletal support to prevent body from buckling as it moves through the water. Requires vertebral column for strength and muscle attachment for lateral undulations of swimming On land, gravity pulls vertebrate body down and puts weight on ventral surface. In fishes, the spine must resist stresses imposed by strong axial muscles. With move onto land, spine had to support limbs, resist bending in some places and increase mobility elsewhere.Review module 9 notesHow is O2 and CO2 transported?Krogh's rule of thumb highlights a limitation in diffusion: diffusion is not suitable for long steps in the pathway for oxygen which is why many animals evolved to using bulk flow to transport O2 over long distances Alternation of bulk flow and diffusion pathway Bulk Flow (long path): Breathing- To pass deep into your lungs from your nostrils, an O2 molecule must travel about 500,000 or 0.5 meters Diffusion (short path): The O2 molecule must cross two simple epithelia, each consisting of a single cell layer. The distance across each epithelium is about 1 um or less Bulk flow (long path): Circulation of blood- To travel in your blood from your lungs to a muscle cell in your calf, the O2 molecule needs to travel about 1,000,000 um Diffusion (short path): The O2 molecule must cross a simple epithelium and a cell membrane, then travel through the cytoplasm. The distance across a cell membrane is about .01 um. The distance from the cell membrane of a muscle to the deepest mitochondrion inside the cell is likely to be 5-50 um.What is partial pressure?the pressure of each gas in a mixturewhat are the different types of breathing organs?Gas exchange membranes of an animal consist of the thin layers of tissue- usually composed of just one or two simple epithelia- where the respiratory gases move between the animals environment medium- air or water- and its internal tissues. All animals have gas exchange membranes of some kind Breathing also called external respiration, is the process by which O2 from the outside environment gets to the gas exchange membranes and the process by which CO2 moves from those membranes to the outside worldwhat are animals evolved specialized breathing organs?Categorize breathing organs into two types: lungs and gills In lungs, the branching and folding of the gas exchange membrane are invaginated (folded inward) into the body and the passages within the breathing organ contain the environmental medium In gills, the branching and folding of the gas exchange membrane are evaginated (folded outward) from the body and are surrounded by the environmental medium (water or air) Breathing can also occur by diffusion (diffusion breathing) if the distances to be covered are short Ex. Insects: gnatswhat does tidal mean?When lungs are ventilated air usually moves both in and out by the same lung passages because air flow occurs first in one direction and then in the opposite direction in the same airwaysanimals with gills....use unidirectional ventilation when there is a one-way stream of water pumping through the passages that lead to the gills, over the gills surfaces, and through the passages that lead away from the gillsPerfusionblood flow through the capillaries or other small blood vessels of a tissueMost types of specialized breathing organs have 3 elements:A ventilation system that brings air or water rapidly by bulk flow to the gas exchange membrane A thin gas exchange membrane of large surface area, with air or water on one side and blood on the other A high rate of blood perfusion provided by the circulatory system, which pumps blood rapidly between the lungs or gills and the rest of the bodyDiffusion takes place much more rapidly through air than...waterAll of the animals with a high metabolic rate are...air breathersThe upper and lower surfaces of each gill filament are folded into many flat folds calledsecondary lamellae the principal sites for respiratory gas exchange, Blood flows unidirectionally through each lamellae. The direction of water flow over the outside surface of the lamella is oppositeBirds have rigid lungs ventilated unidirectionally by air sacsThe breathing system of a bird includes air sacs These thin walled sacs, which fill much of the intestinal space in a birds body connect to airways in the lungs The air sacs do not participate in exchange of O2 and CO2 between the air and blood Their function is ventilation, acting like bellows and forcing air to flow past the gas exchange membranes in the rigid lungs Airflow in the lungs and air sacs of birds Inhalation: the anterior sacs expand and fills with gas that has passed through the lungs, the air flows through the parabronchi (long tubes of small diameter) from posterior to anterior, the posterior air sacs expand and fill with fresh air coming directly from the environment Exhalation: The anterior air sacs are compressed discharging stale gas stored in them, as during inhalation air flows through the parabronchi from posterior to anterior, the posterior air sacs are compressed and the fresh air in them is directed primarily into the lungsSome animals lack specialized breathing organsFlatworms or sponges They take up O2 and void CO2 across their body surfaces They have not evolved because they are low metabolic rates and they have body plans in which most of their cells are close to a body surfaceThe lungs are ventilated by the expansion and contraction of the thoracic cavityMammalian lungs are suspended in the thoracic cavity bound by a rib cage by a sheet of muscle called the diaphragm Increase in volume of the cavity pulls on the walls of the lungs, thereby expanding the lungs and causing inhalation Two muscles or sets of muscles are critical for breathing: Diaphragm and the intercostal muscles that run between adjacent ribs Diaphragm is dome shaped when it is not contracting protruding upward from the abdomen and flattens when it contracts adding more volume to the cavity There are two sets of intercostal muscles One set when contracting changes the positions of the ribs in a way that enlarges the volume of the thoracic cavity The other set makes the thoracic cavity smaller when it contracts When at rest, inhalation is active and exhalation is passivewhat are the two types of circulatory systems?A closed system is if the blood is always contained within blood vessels as it circulates An open system is if the blood exits blood vessels as it flows through the bodyThe vessels of the microcirculation:Arterioles Has smooth muscle fibers Control the autonomic system Can contract and relax to change diameter of vessels Vasoconstriction: small diameter Vasodilation: large diameter Vasomotor control Control where blood flows Capillaries Walls consist of vascular endothelium Where O2, CO2, and other minerals are exchanged Play this role for two major reasons Are found near every tissue cell Capillary walls consisting of only flattened endothelial cells are less than 1 micrometer thick and in many tissues there are gaps between adjacent endothelial cells These properties mean that the exchanges can happen via diffusion venules Last to pass through from the capillariesHow do open circulatory systems work?The heart typically pumps blood into arteries that carry the blood for at least a short distance where the vessels end and the blood pours out into spaces surrounded by ordinary tissue cells No distinction between blood and interstitial fluidTwo blood respiratory pigmentshemoglobin is an iron-containing protein to which O2 binds at the molecular sites where iron atoms occur hemocyanin is the second more widely distributed respiratory pigment Metal-containing protein which O2 binds at the molecular sites where metal atoms occur The metal is copper Hemocyanin is dissolved in blood plasma Found in mollusks and arthropodsMyocardiumheart muscleA hearts stroke volumeis the volume of blood it pumps per beatA hearts cardiac outputis the volume of blood it pumps per minute, calculated by multiplying its stroke volume by the number of beats per minuteThe mammalian heart consists of...four-chambers: two highly muscular ventricular chambers which contract together and two less muscular atria which also contract togetherIn most fish the heart consists of...two primary, muscular chambers: an atrium (a thin walled chamber blood passes on its way to the principal pumping) and a ventricle (thick-walled muscular chamber)The cycle of contraction and relaxation is the cardiac cycleThis cycle has two phases: systole (ventricles contract) and diastole (ventricles relax) Left ventricle is more muscular than the right and develops higher pressuresCrustacean hearts are...Single-chamberedEach heart beat is initiated by pacemaker cells which are modified muscle cells found in a localized part of the...right atrial wall termed sinoatrial node (S-A)Countercurrent heat exchangehelps animals conserve heat depending on parallel arrays of arteries and veins to keep their red swimming muscles warm (in tuna)what is the CNSThe major parts of the nervous system are the brain and spinal cordwhat is the PNSAll parts are composed specialized nerve cells or neurons which often have a highly elongated structureWhat is the autonomic nervous system?controls involuntary functions -The gut, blood vessels, bladder, eyes, airways of the lungs, and reproductive organs -Controls exocrine glands: tear and sweat glands -Controls some endocrine glands: adrenal medullary glandsANS has 3 Divisions:Enteric division: Composed of the nerve cells internal to the gut wall Sympathetic division Parasympathetic divisionAll vertebrate brains consist of three major regions:The forebrain: Cerebral hemispheres are important in carrying out high-order sensory, motor, and integrative functions In humans, they are responsible for language and reasoning Midbrain Hindbrain: The most posterior part of the hindbrain is the medulla oblongata All information traveling between the brain and spinal cord must pass through this structure Shape and structure of this part has changed littleparasympathetic nervous systemrest and digestsympathetic nervous systemfight or flightThe two types of excitable cells are...Neurons Muscle cellsMost neurons have 4 anatomical regions:A set of dendrites: Relatively short cell processes (extensions) that tend to branch from the cell body like twigs on a shrub The dendrites are typically the principle sites where incoming signals arrive from other cells A cell body: Contains the neurons nucleus and most of its organelles From the perspective of signaling, the most important function of the cell body is to integrate incoming cells Neurons integrate signals Axon hillock: the part of the neuron where the cell body transitions to the axon is particularly engaged in integration An axon: A particularly long cell process that is specialized for long-distance signal conduction A set of presynaptic axon terminals: These terminals make synaptic contact with other cells, enabling signals generated by one neuron to initiate signals in other neurons or in muscle cells They innervate the cells with which they make synaptic contactNervous system has two types of cells:Neurons - Glial cells (glia or neuroglia): -Glial cells are not excitable and do not conduct action potentials -provide metabolic support or neurons, help regulate the composition of the extracellular fluids bathing the neurons, and perform immune functions -help regulate signal transmission across synapses -In vertebrates, certain glial cells wrap around axons forming myelin sheath (multilayered wrap of cell membrane forms a lipid-rich electrical insulation)process of transmitting signal from one neuron to anotherWhen an action potential arrives at an axon terminal the terminal releases Ach into the synaptic cleft by a mechanism that depends on voltage-gated calcium channels The action potential causes Ca2+ channels in the presynaptic membrane to open and Ca2+ diffuses into the axon terminal through the open channels because the concentration of Ca+ is greater outside the cell than inside Increased Ca2+ inside the terminal induces synaptic vesicles to fuse with the presynaptic membrane releasing Ach into the synaptic cleft by exocytosis The response of the muscle cell depends on ligand-gated receptor proteins in the postsynaptic cell membrane. These receptors which are gated by Ach act as ion channels when they are open. When Ach is released by the presynaptic cell it diffuses across the synaptic cleft Binds to the Ach-gated receptors, the receptors open allowing Na+ and K+ to diffuse through with influx of Na+ being dominant The rapid influx of Na+ causes a large, graded depolarization of the postsynaptic membrane which induces graded ionic currents that spread to neighboring regions of postsynaptic cell membrane There are voltage gated membranes Na+ and K+ channels. The membrane depolarization in these neighboring regions is great enough for the voltage gated Na+ channels to open initiating an action potentialNeurotransmitters fall into 3 major chemical categories:Amino acids: Glutamate, glycine, aminobutyric acid (GABA) Biogenic amines: Acetylcholine, dopamine, norepinephrine, and serotonin Peptides: Strings of amino acidsInterneuronsConfined to the CNS Do not physically extend into the PNS Engage in integrative, command, and information-storage functions Consist of most of the neurons in the CNSSensory neuronsCarry signals to the CNS from sensory cells or organsefferent neuronsNerve cells that conduct impulses away from the central nervous systemEndocrine cells are defined...they secrete hormones into the bloodThe endocrine system-Slow and broadcast -They are slow because the hormone has to circulate all the target tissues and organs -At least several seconds or minutes -Cells release hormones or signals into the blood and they are carried throughout the body reaching the tissues and organs -Controls more widespread, prolonged processes such as development, reproductive cycles, or changes in the metabolism that are sustained for many minutes, hours, or daysTwo types of glandsendocrine Do not have outflow ducts Secrete their products into the blood flowing the nearby blood capillaries or other blood passages In some cases, large numbers of endocrine cells of a particular kind are grouped together to form a tissue or organ called an endocrine gland Ex. Thyroid and adrenal gland Exocrine Have outflow tubes (ducts) exiting the body -Mammary, salivary, sweat, tearHierarchy of Systems in Ecology: Order, Definitions & ExamplesIndividual (single wolf) --> population (wolf pack) --> community (wolves interacting with other populations and individuals in forrest) --> landscapes (wolves and deer living in the same forrest) --> Biosphere (all communities on Earth's atmosphere)Species InteractionsInterspecific competition (-/-): Refers to interactions in which individuals of two different species decrease one another's fitness (-/-) because they require some of the same resources When other individuals use a resource it is not available to others and may affect that populations reproduction There generally is some limiting resource that is in shortest supply relative to demand and those who share a need for this resource will compete Some organisms are limited by space in which to grow Plants may compete for the attention of animal partners that pollinate Barnacles encrusting a rocky shore Birds building a nest Consumption interactions (+/-): Those in which organisms obtain nutrition by consuming or harming other living organisms or are themselves consumed or harmed One is positively affected (obtaining nutrition) and one is negatively affected (harmed or consumed) Consumption interactions include predation: one of the species is the predator, kills and eats individuals that are the prey Herbivory where an herbivore eats part or all of a plant to the plants detriment Parasitism where the parasite consumes part of a host individual but usually does not kill it Mutualism (+/+): An interaction that benefits both species (+/+) Ex. An interaction between leaf-cutter ants and the fungus they cultivate is mutualistic: the ants feed, cultivate, and disperse the fungus. The fungus in turn converts inedible leaf fragments into special fungal structures that the ants can eat Ex. Seed-dispersing animals, Humans and gut microbes Mutualism varies in the degree to which they are essential or beneficial but not essential to one another Commensalism (+/0): Commensalism influences only one participant which benefits, while the other participant is unaffected Unlike all the other interactions which influenced the fitness of both participants Ex. Species whose feeding behavior makes food more accessible for another Cowbird follows grazing ungulates (hoofed mammals like cattle or bison) and feed on insects flushed as they move and feed The cowbird has no effect on the ungulate fitness but the ungulate has an effect on the cowbirds fitness Amensalism (-/0): Affects only one party in the interaction which is harmed Ex. Elephants moving through a forest or bison grazing the plains crush insects and plants with each step but the mammal is not affected Tend to be more unintentional than the other interactionsEcological communitythe set of species that occur together at the same time and placeThree major processes contribute to this dynamism: colonization and extinction, disturbance, and global changeColonization and extinction: -New species arrive from time to time and resident species may be excluded by the new comers or may go locally extinct by chance -Dispersal is an ongoing process that delivers a constant influx of new individuals to all but the most isolated locations -When individuals arrive in a new location that already contains a population of their species, they add to its size; when those individuals are members of a novel species they may establish a new population and add another species to the community Disturbance: -An event that causes sudden environmental change is a disturbance and can alter communities Ex. Volcanic eruption, wildfires, hurricanes, landslides, floods, and activities of animals -Disturbances can occur on a small spatial scale, for example, a tree falling creates a gap in the forest canopy -As communities develop following a disturbance their structure often undergoes a more or less predictable sequence of changes called a succession Several factors are responsible for predictable features of post-disturbance community changes -Colonization, the process by which new species enter communities -Predictable post-disturbance environmental change --State transition: a distinctly different community (change) Global change: Any change in the physical environment of a location, or in the regional pool of species that can colonize it, can alter the structure of the resident communityNet Primary Productivity (NPP)the rate at which primary producers generate dry biomass-- is a measure of the rate at which materials, as well as energy, flow between abiotic and biotic components of ecosystemsNPP increases withprecipitation and temperatureIn aquatic ecosystems, NPP is affected more strongly by...light and nutrients than by water temperature since its far less variable than air temperatureEarth is an open system with respect to...energy b/c waste heat produced by organisms is released back into spaceEarth is a closed system with respect to...matter b/c little matter escapes from earths gravitybiogeochemical cyclesMatter is cycled among the compartments of the global ecosystem by processes that are biological, geological (physical), and chemicalClimate is influenced by...the chemical makeup of Earth's atmospherehuman activities that are contributing to global warming are...Expansion of livestock grazing, agriculture, and off-road vehicle traffic Dust and dark-colored soot particles from fossil fuel burning that are deposited on snow and ice increase the absorption of incoming solar energy When we increase particulates in the atmosphere by generating dust or clearing land, we increase the amount of incoming solar radiation that is reflected back into space, which has the effect of decreasing the temperature of the lower atmosphere and Earth's surface -Global warming increases the frequency and intensity of extreme weather events, such as heat waves, droughts, and stormsNatural impactsSome are reflected back into space, water droplets or ice crystals in clouds, or gas molecules in the atmosphere Some are reflected back into space when they hit Earth's surface Some are absorbed rather than reflected by materials in the atmosphere Some of incoming solar energy is absorbed by Earth's surfacetragedy of the commonsshort term self interest against the common good ending badly for everyone -allows one individual to benefit spreading the negative side affect to everyone else -results like overfishing, over grazing, overpopulation, and pollution -optimizing for the self in the short term isn't optimal for anyone long term