chapter 16 discover biology notes
chapter 16 discover biology notes BISC 1006
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This 5 page Class Notes was uploaded by Nadya Notetaker on Monday January 18, 2016. The Class Notes belongs to BISC 1006 at George Washington University taught by Scully in Winter2015. Since its upload, it has received 27 views. For similar materials see The Ecology and Evolution of Organisms in Biology at George Washington University.
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Date Created: 01/18/16
Chapter 16 Notes speciation is process of making new species through reproductive isolation of lineages which causes more diversity macroevolution is large scale evolution which is caused by natural selection that causes radical changes in body plan not just a change in allele frequencies changes on Earth took place for billions of years radioisotopes are unstable forms of elements that decay to more stable forms at a constant rate over time Earth’s age is 4.6 billion years which is known as geologic time fossils are preserved remains or impressions of individual organisms that lived in the past usually bones, teeth, and shells preserved in sediment which harden into rock hard to preserve because most organisms did not die where sediments form important for studying evolution b/c it shows past organisms aren’t like the ones today order of which organisms appear in fossil record support evolution order only tells the relative age of fossils and which ones are older carbon14 helps estimate the age of the fossil better only dates fossils up to 70,000 yrs ago uranium235 has a halflife of 700 million yrs fossils can still be dated if they don’t have radioisotopes by dating rocks around it fossil record is incomplete b/c... most organisms decompose fast after they die most do not form fossils even if they are fossils, erosion, lots of heat or pressure can destroy it whales are closely related to hoofed mammals pakicetus is an early whale ancestor bones in ankle show that it’s related to hippo, camel, giraffe whales have common ancestor with artiodactyl b/c of the weird shape of anklebone which helped it on land oldest known rocks are 3.8 billion yrs old cell structures have been found on stromatolites which existed 3.5 bya (billion yrs ago) first life were prokaryotes eukaryotes formed 2.1 bya 2.8 bya, photosynthetic bacteria released oxygen which began to support eukaryotic life 2.1 bya, once O2 made up 23% of atmosphere precambrian period 650 mya eart is filled w/ shallow seas w/ plankton protists, small multicellular animals, algae lived in H20 soft bodied multicellular animals began to appear cambrian period 540 mya lots of diversity and forms of life appear during the Cambrian explosion which lasted 510 mill. yrs scavengers + herbivores transformed into predators adaptive radiation led to diversification of life adaptive radiation = one lineage gives rise to many descendants devonian period 360 mya earth is covered w/ plants lots of shrubs and trees plants evolved to live on land. how? wateproof cuticle vascular sys. for transport of h20 and nutrient support tissue like wood leaves and roots seeds tree growth form specialized reproductive structure mycorrhizae are mutualistic associations that helped plants and fungi live on land spiders and millipedes lived 410 mya. insects lived 400 mya. first vertebrates to colonize land were amphibians in 365 mya which descended from lobe finned fish & then evolved into reptiles reptiles could reproduce w/out returning to water insects >fish>amphibians>reptile>dinosaur>mammal plate tectonicsis the mvmt of continents over time continents float mantle, hot layer of semisolid rock continents collide to form supercontinents (ex. pangaea) plate tectonics can lead to: geographic isolation which reduces gene flow speciation is promoted affects climate changes flow of oceans heat and moisture is distributed differently We have had 5 mass extinctions where lots of species went extinct more than half died each time caused by climate change, volcano, asteroid, change in gas levels in sea/air permian extinction occurred 250 mya where lots of sea animals and insects went extinct cretaceous extinction occurred 65 mya where dinosaurs died which was caused by asteroid collision mass extinction has 2 major impacts entire groups of organisms die lets surviving species experience adaptive radiation studying evodevo or evolutionary developmental biology helps us understand macroevolution study impact gene expression has on body plans homeotic genes cause the dvlpmt of structure in embryological dvlpmt (for ex. there is a homeotic gene that regulates limb dvlpmt by controlling expression of all other genes for limb growth in embryo not every cell expresses the same genes, different cells will turn on different set of genes homeotic genes are expressed in specific part in embryo atavistic traits and vestigial traits give proof that many body plans exist b/c of dvlptml changes. atavistic traits represents a reversion to ancestral state (ex. tails in humans). We don’t have tails anymore b/c homeotic genes are turned off :) taxonomy is organizing and classifying the array of biodiversity phylogenetics is the sorting of organisms based on morphological and genetic similarities to make evolutionary trees living things diversified lineages or many lines of descent evolutionary trees are vital to understanding lineages node = where ancestral group split into two separate lineages. it represents the most common ancestor of two lineages homologous traits are similar characteristics b/c of similar ancestry (you look more like your sibling than your cousin) shared derived traits are evolutionary novelties shared by ancestor and descendants but not seen in groups that are not direct descendants of ancestor linnaean hierarchy was made by Linnaeus to classify organisms species is smallest unit and forms a genus most broad to least broad taxon or group (kingdom, phylum, class, order, family, genus, species) KPCOFGS Species genus = Scientific name (ex. Homo sapiens)
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