Exam 1

Biology is the study of life at all levels of organization, roughly from molecules to the thing related. Evolution by natural selection is responsible for the diversity of adaptations found in living organisms. Life first arose by chemical evolution. Biological evolution began with the formation of cells. The scientific method ? make observations, ask questions, form hypothesis, make predictions, and test hypothesis. Hypothesis ? answer to questions. Experiments: Comparative and controlled. Wise public policy decisions must be based on accurate scientific information. Biologists are often called on to advise governmental agencies on the solution of important problems that have a biological component. Scientist ? observe and conduct experiments to find new things that change the way we do or learn things. Ex: genomes, genes, etc. Biologists ? found information that helps us understand how and why organisms differ, how they function, and how they evolved. All cells come from pre-existing cells. A phylogeny is a description of the evolutionary history of relationships among organisms (or their parts). A phylogenic tree is a diagram that portrays a reconstruction of that history. Commonly used as: depict the evolutionary history of species, populations, and genes. Macromolecular aggregates: chain, lattice, suspensions. Ex: DNA (cell-working unit). Hierarchy of life Organelles ? a group of unlike molecular aggregates. Organelle System ? a group of organelles functioning as a unit. Cells ? basic replicating unit. Tissues ? groups of cells. Organs ? groups of unlike tissue Organ System ? groups of organs and tissues Organism ? functional unit ability to act or function independently Population ? potentially interbreeding individuals in given locality Community ? groups of unlike species population in given locality Ecosystems ? Biotic and Abiotic components (including living and non living) Diversity ? richness = # of kinds (species) Selection Stabilizing does not equal evolution. Directional does equal evolution. Disruptive (Diversified) does equal evolution. Adaptation occurs when some individuals in a population contribute more offspring to the next generation than others, due to individuals adapting to the environment that influences such reproductive success. Fitness ? reproductive contribution of a phenotype to subsequent generations relative to the contributions of other phenotypes. The average rates of survival and reproduction of individuals determines the phenotype ? fitness. Evolution ? 2 propositions Species are not immutable; They change over time. The process that produces these changes is natural selection. Evolutionary mechanisms are forces that change the genetic structure of a population. Ex: mutation, gene flow, genetic drift, nonrandom mating, and natural selection. Darwin ? Responsible for concept of evolution by natural selection. Collected 100?s of species, excellent observer, filled many notebooks, tied observations to his and other?s previous work, and sailed on the HMS Beagle to the Galapagos Islands. He also proved wrong the current time Evolution by Lamarck. Competition driven change: extinction or character displacement and speciation. Postulated ? single arriving species ? diversified to fill different feeding niche. Biogeography ? is the scientific study of the patterns of distributions of populations, species, and ecological communities across the Earth. Biogeographic regions are based on the taxonomic composition of the organisms living in them. Biogeographically Patterns Relative to mainland Between close islands - more similar. Distance ? less similar. Species radiations on isolated islands are higher than less isolated. Convergence on different continents Apparent in fossil record records anomalies. An organism?s genome is the fullest of genes it contains, as well as any noncoding regions of the DNA. The positions of genes, as well as their sequences are subject to evolutionary change; as are the extent and location of noncoding DNA. The field of molecular evolution concerns relationships between the structures of genes and proteins and the function of organisms. The concept of homology (similarity that results from common ancestors) extends down to the level of particular positions in nucleotide or amino acids sequences. Sequence alignments from different organisms allow us to compare the sequences and identify homologous positions. Analogous traits convergence of structures due to similar selection processes. Converge ? they evolve the same adaptations. Simplest explanation is best, vestigial structures, branching patterns in lineages, embryology (patterns of early development ? natural selection), Molecular ? a lot of redundancy so changes often are neutral to selection. Molecular embryo data Redundancy in genetic code. 2 mutations on average per generation. Can use to date events in remote past. Darwin did not have Plate tectonics ? movement of continents relative to one another. Discovered in cold wars in the 1950?s to detect submarine activity. Volcanic activities due to crack of the plates. The climate of a region is the average of the atmospheric conditions over a long period of time. Weather is the short-term state of those conditions. Warm air holds more H2O than cold air (humidity higher near equator). Warm air also rises. Adiabatic cooling: Air gets thinner as move up in elevation Molecules move apart and fewer collisions Air temperature decreases Polar & temperate regions most influenced by Earth?s tilt: seasonality. Differential Heating ? energy from sun reaching the earth drives almost every known physical and biological cycle in earth system. Earth?s tilt and Rotation around Sun, Coriolis Force (influences wind and water currents ? function of shapes), Topographical effects (regional ? mountain, hills, and water bodies) Macro-Climate (Chest Height) Micro-Climate (forest floor, under logs, etc.) Shades decreases solar radiation Decreased wind = decrease cooling and increase humidity The rate at which solar energy arrives on Earth per unit of Earth?s surface depends primarily on the angle at which sunlight arrives. Organisms respond behaviorally to short-term environmental changes A biome is a terrestrial environment defined by the growth form of its plants. Common biomes: forests, grassland, desert, and tundra. The species that live and interact in an area constitutes an ecological community. Predation ? interactions in which one participant is harmed, but the other benefits (+/-) Competition ? interactions in which two organisms use the same resources, & those resources insufficient to supply their combined need (-/-) Mutualism ? interaction in which both participants benefits (+/+) Commensalisms ? interactions in which one participant benefits, but the other is unaffected (+/0) Amensalism ? interactions in which one participant is harmed, but the other is unaffected (0/-) Charles Sanders Peirce (1839- 1914) ? Philosopher, founder of ?American Pragmatism,? wrote The Fixation of Belief (1877). 4 Methods: Tenacity, Authority, A priori, Science Tenacity ? holding on to a belief (Ex: Food preferences) Authority ? beliefs are fixed according to social institution or accepted w/o justification (Ex. Book, person) A priori ? ?agreeable to reason,? it makes sense, intuition. (Ex: The earth is flat?) Science Method ? same as a priori, but involves critical testing (hypothesis, deriving, & experiments) Biotic Duplicate themselves Complex & highly organized metabolism Homeostasis Movement Responds to stimuli (light, sound, etc.) Grows (increase) Reproduces ? makes accurate/precise copies of self Asexual ? exact copies Sexual ? variability Higher levels build on previous levels and more complex levels ? Hierarchy 4 Common threads underlie Biodiversity: Evolution by natural selection Geological history of the Earth Climate Trophic Structure EVOLUTION Fact and Theory Definition: gradual modification of populations of living things over time, sometimes resulting in the development of new species. Book Definition: Any gradual change. Organic or Darwinian evolution, often referred to as evolution, is any genetic resulting phenotypic change in organisms from generation to generation. Fact: has and does occur Theory: mechanism that cause it; a constant that ties together diverse sets of observations broad explanatory powers and based on abundant evidence. Ernst Mayr (1905-2005) Observable Facts Organisms produce more offspring than the environment can support (will die before reproductions) Variation among individuals exists in traits ? phenotypes Because not all individuals can survive to reproduce Theory of Evolution by Natural Selection Population will change each generation Trait Distributions Phenotype: physical, physiological, or behavioral traits Genotype: underlying genetic make-up ? blue print that produces phenotype ? development and experience Frequency: numerical representation of a phenotype in a population relative to other phenotypes. ENERGY IS NOT RECYCLED Fossil Record ? means ?dug up? Fossil Preservation Generally non oxygen environment Exception: not object to decay Mineral Replacement (time is condition dependent) Embedded in amber or tar Frozen Embalmed-logs It is important to be able date fossils at least as to relative age if we are to understand phylogenetic sequence. Hulton 1795 ? Earth is always changing ? it is not static Volcanic Activity Mountain Building Erosions and Weathering Sediments Burial in Crust Needed: Half-Life, Relative quantity of parent isotope, and radioactive. Extant ïÆ? Living Fluctuations of the Earth?s magnetic field Race mezation of amino acids decompose at a constant rate left handed structure to right hand ? used in dating fossils with organic matter. Radioactive Dating (isotopes) CLIMATE Earth supports a diversity of organisms Temporal and spatial variations Climate is a major contributing factor Rules of Ecology ? Study of organisms and interactions with their environment biotic or abiotic Everything is connected to everything else. Everything must go somewhere. No such thing as a free lunch Ecosystem: functioning system consisting of organisms and the physical environment they exist in. System: interdependent components that interact, forming a unified whole. Pyramids Energy ? Joules tied Biomass ? the dry mass of organic Numbers of organisms within BIOMES Tropical Rainforest Richest Biodiversity Wet and Warm 200-450cm annual precipitation 0-10 degree latitude Temp: 20°C Range Temp: 2.2°C Savanna Low latitudes inland 85- 180cm annual precipitation 0-10 degree latitude Temp: 30°C Range Temp: 10.7°C Dessert Mountain rain shadows included < 25 cm precipitation Temp: 35°C Range Temp: 9°C Temperate Forest Precipitation: 75-126 cm Moderate rainfall and temperatures 30-60 degree latitude Temp: 23°C Range Temp: 5.4°C Grassland Precipitation: 50-90 cm Mid latitudes 30-60 degree inland Temp: 15°C Range Temp: 24°C Chaparral Precipitation: 26-50 cm East of oceans 40-60 degree unique coasts Temp: 15°C Range Temp: 7°C Taiga/Boreal Precipitation: 40-60 cm High Latitudes ? 60-80 degrees Temp: -5°C - 5°C Range Temp: 41°C Tundra Precipitation: 10-25 cm Polar regions 90-100 degree latitude Temp: -10°C Range Temp: 28°C