Multicellular Life

Organismic and Evolutionary Biology

The Cell

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2/7/12 1 LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick Cellular Respiration and Fermentation Chapter 9 Overview: Life Is Work • Living cells require energy from o

Chapter_9_Slides.pdf-LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH

Lecture 18  Carbon Cycle o Processes of Carbon Cycle  1) Photosynthesis and Respiration  2) Ocean-Atmosphere Exchange  3) Precipitation of Carbonates o 1) Biotic Carbon Exchange  Photosynthesis : An assimilatory process that incorporates inorganic forms of elements into organic forms  Cellular Respiration : A dissimilatory process that transforms organic forms of elements into inorganic forms o 2) Ocean-Atmosphere Exchange  CO 2 dissolves readily in water  Exchange of carbon across the atmosphere-ocean interface links the terrestrial and aquatic carbon cycles  Oceans are a sink for CO 2 produced by fossil fuel combustion o 3) Precipitation and Sedimentation of Carbonates  Dissolution and Precipitation of carbonates occur in aquatic systems  Calcium ions combine with carbonate ions to form calcium carbonate  Precipitation of calcium and magnesium carbonates leads to formation of limestone and dolomite rock  Carbonate sediments represent the single largest component of carbon on the planet o Carbon Cycle and Burning Fossil Fuels  Prior to the Industrial Revolution, CO 2 added to the atmosphere by respiration of terrestrial organisms was balanced by primary production of terrestrial organisms  Since the Industrial Revolution, reliance on fossil fuels has increased steadily  At present:  Burning of fossil fuels generates 5 gigatons of carbon annually  Forest clearing/burning generates 2 gigatons of carbon annually  Human activity has increased annual carbon flux by ~6% o The Greenhouse Effect  1) Short wavelength sunlight passes through atmosphere  2) Absorbed light warms surface  3) Warm surface emits infrared radiation  4) Infrared radiation is absorbed by atmosphere (CO 2 , H 2 O) and converted to heat  This process is natural, but the increased amounts of greenhouse gases in the atmosphere because of burning fossil fuels increases step 4 = global warming  Nitrogen Cycle o Major reservoir is atmospheric N 2 o Nitrogen enters biological pathways primarily through nitrogen fixation , which is accomplished mostly by microbes o Plants use Nitrate (NO 3 - ) and ammonium (NH 4 + ) o Anthropogenic nitrogen sources NOW EXCEED natural biological nitrogen fixation in terrestrial ecosystems o Ecological Consequences of Anthropogenic Nitrogen Deposition  Coastal Marine Dead Zones  Nitrogenous runoff adds TONS of nitrogen to the Gulf of Mexico (and other coastal areas)  Influx of nutrients increases algal populations (algal blooms)  Respiration by bacteria depletes dissolved oxygen, resulting in hypoxia and causing a dead zone (particularly on shallow sea floors)  Shrimp die, and fish leave or die  Phosphorous Cycle o Plants use PO 4 3- (phosphate) o Relatively small amounts of phosphorous move through the atmosphere o Most phosphorous is in marine sediments o Phosphorous often limits productivity  Phosphorous forms insoluble compounds with iron, aluminum, and calcium (depending on the pH level and oxygen level)  Aquatic systems act as a phosphorous sink  Most phosphorous is locked up in marine sediments  Extractable sources of phosphorous may limit agricultural productivity in the near future  Biodiversity

BILD | 3 | Organismic and Evolutionary Biology | lecture notes | Lecture 18  Carbon Cycle o Pr

Lecture 09  Phylogeny Overview o Phylogeny : Evolutionary history of a group of species  Branching diagram  Shows relationships among taxa  Shows patterns of ancestry  Use all possible types of data o Phylogenetic trees must be inferred  Reconstructing the path we didn’t see o Hierarchal classification is reflected in the branching of phylogenetic trees o For the most part, classification represents real history of evolution o For the most part, organisms that look more alike are most closely related (but not always true)  Phylogenetic Tree Terminology o Node (branch point): Represents the common ancestor of lineages  An unresolved node is known as a polytomy o Species or Taxa : The leaves of the tree (the very ends of the tree) o Root : The beginning of the tree corresponds to the common ancestor for all of the species in the tree o Time : Y-axis o Sister Taxa : Share an immediate common ancestor and are each other’s closest relatives o Branching Pattern (Topology ): Informative o Branch Length : May or may not be informative  Phylogenetic Trees: More Information o Branch tips can be arranged in different ways, but the relationship between nodes can be the same o Monophyletic Group : Contains common ancestors and ALL descendants  So you should be able to just cut the tree in one place to make the subtree o Paraphyletic Group : Contains common ancestor and some but NOT ALL descendants o Polyphyletic : Taxa with different relative ancestors o Ingroup : Group of taxa of interest, assumed monophyletic o Outgroup : One or more taxa assumed to be outside the ingroup  How to Build a Phylogenetic Tree o Measure as many character traits as possible in the group of organisms  Traits to measure: morphological, behavioral, genetic, etc. o When character states all agree, building a tree is easy  Similar Traits o Homology : Similarity due to inheritance of traits from a common ancestor  Ancestral Homology : Originated in an ancestor of the taxon  Derived Homology : Evolutionary novelty unique to a clade  Synapomorphy : Shared derived homology (the characteristic at the beginning of a branch) o Homoplasy : Similarity that came about separately (not inherited from a common ancestor)  Tree Building Techniques o Outgroup Comparisons  Why are Phylogenies Useful/Important? o Provide an efficient structure for organizing biodiversity o Allow us to develop a conception of the totality of evolutionary history o Can help us answer specific questions of how evolutionary changes arose

BILD | 3 | Organismic and Evolutionary Biology | lecture notes | Lecture 09  Phylogeny Overvie

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