Chapter 4

StudyBlue printing of Chapter 4 html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, font, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td { margin: 0; padding: 0; border: 0; outline: 0; font-size: 100%; background: transparent; } body { line-height: 1; } blockquote, q { quotes: none; } blockquote:before, blockquote:after, q:before, q:after { content: ''; content: none; } /* remember to define focus styles! */ :focus { outline: 0; } /* remember to highlight inserts somehow! */ ins { text-decoration: none; } del { text-decoration: line-through; } /* tables still need 'cellspacing="0"' in the markup */ table { border-collapse: collapse; border-spacing: 0; } /* end RESET */ .header { min-width:800px; } .logo { padding:6px 20px 2px 20px; margin:0; font-size:25px; font-weight:bold; color:#808285; position:relative; border-bottom: 1px solid #c5c5c5; } .logo-blue { color:#70adc4; } .logo-desc { font-weight:normal; font-size:19px; color:#cccccc; margin-top:50px; position:absolute; display: none; } .back-button { position:absolute; top:20px; right:20px; font-size:13px; line-height:25px; color:rgb(0,175,225); font-weight:normal; } .back-button a { color:rgb(0,175,225); } .instructions { padding:0; margin:0; width:100%; position:relative; color:rgb(100,100,100); } .step-holder { border-left:1px solid #ededed; margin-left:20px; } .steps { padding:15px 0; float:left; width:24%; border-right:1px solid #ededed; text-align:center; } .steps-01 { } .steps-02 { } .steps-03 { } .steps-04 { } .label { padding:5px 10px; } .print-button { } .print-button a { background-color:rgb(0,175,225); color:white; line-height: 19px; padding:9px 8px 5px 30px; font-size:14px; text-decoration:none; background-image: url(images/printer.png); background-repeat: no-repeat; background-position: 7px 50%; -moz-border-radius: 5px; -webkit-border-radius: 5px; } .print-button a:hover { background-color:black; } .theNote .content { width: 8.0in !important; margin: 5px auto; padding:20px; background-color:white; } .theNote .header { border-bottom: 1px dashed #C8C8C8; font-size: 17px; padding: 0 0 10px; line-height: 19px; color: #00ADE1; min-width:500px; } .theNote .body { font-size: 14px; line-height: 19px; padding: 10px 0; } .theNote{ padding:6px 0; clear:both; background-color: rgb(200,200,200); } .theNote h3{ color: rgb(100,100,100); } .theNote h1, .theNote h3{ background-color:white; padding:2px 20px; width:8.0in !important; margin: 0 auto; font-size: 15px; } .theNote h1{ padding-top: 10px; font-size: 15px; } .theNote h1:first-child{ font-size: 20px; } .theNote h3 { font-size: 14px; font-weight: normal; } #options { border: 3px double #ccc; padding: 5px 12px; margin: 10px 50px 10px 20px; float: left; } #info { border-top: 1px solid #ccc; padding-top: 5px; font-style: italic; } li { margin: 5px 10px 5px 25px; } ul li { list-style: disc; } ol li { list-style: decimal; } img { border: 0; } table { clear: both; width: 100%; border: 1px solid #c5c5c5; border-width: 1px 0; margin: 0; page-break-after: always; } table#page { page-break-after: auto; } td { text-align: center; font-size: 12px; border-bottom: 1px dashed #c5c5c5; height: 1.75in; width: 50%; padding-left: 15px; } .leftside { border-right: 1px solid #cccccc; padding: 0 15px 0 0; } .bottom td { border-bottom: none; } .clearfix { clear:both; line-height:1px; height:1px; } img { max-width:80%; max-height:150px; margin:20px; } @media print {.header { display: none; } .content .header{ display:inherit; } table { border: 1px dashed #bbb; border-width: 1px 0; } .theNote{ background-color:white; } } macroevolution: the long-term pattern of evolution, including the origin and evolution of species, is generally more difficult to grasp creationism- argues that we cannot directly observe changes over millions of years and therefore cannot conduct scientific tests geology and astronomy are historical in nature The Birth and Death of Species Charles Darwin did not focus much on this question: why do some species die out?how do new species come into being? he sought to explain the basic nature of evolutionary change, believing that extension of these principles could explain the formation of new species What Is a Species? biological species concept: a definition of species that focuses on reproductive capabilities, whereby organisms from different populations are considered to be in the same species if they naturally interbreed and produce fertile offspring first, organisms from different populations must be capable of interbreeding second, these matings must occur in nature third, the offspring must be fertile any system of classification tends to ignore variation withing groups in the real world, however, evolution and variation work to break down rigid systems of classification Species Change there are two different wways of looking at species over time first, a single species can change over time such that enough differences accumulate that we would choose to give it a different species name anagenesis: the transformation of a single species over time the traditional biological species concept doesnt really apply by necessity isolated form each other reproductively because they lived at different times many researchers modify the species concept to deal with this situation chronospecies: labels given to different points in the evolutionary lineage of a single species over time. As a species changes over time, the different stages are labeled as chronospecies in recognition of the biological changes that have taken place cladogenesis: the formation of one or more new species for another overtime the naming of species might adhere to an evolutionary model or might serve only as convenient labels of physical variation Speciation genetic differences between populations come about as a result of evolutionary forces Reproductive Isolation reproductive isolation: the genetic isolation of populations taht may render them incapable of producing fertile offspring Speciation: the origin of a new species, the formation of a new species from a a prents species is the elimination or reduction of gene flow between populations gene flow acts to reduce differences between populations populatiosn must become genetically isolated from one another for speciation to occur most common form of isolation in animal species is geographic isolation when two populatiosn are separeted by physical barrier ,such as a river or mountaing renge, or by great distances, gene flow is cut off between populations other mechanisms may also cause isolation, some of thees can operate withing a single region, behavioral differences sucha s feeding habits Genetic Divergence isolation is the first step in the speciation process isolatio does not guarantee speciation mutation might act to increase variation among populations because it occurs independently in the genetic composition of separate groups, without gene flow to spead them, individual mutations will accumulate in each group, making isolated populations genetically divergent genetic drift also contributes to differences in allele frequencies among small populations Adaptive Radiation