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Transcript
Question: Where did Darwin travel to where he observed many unusual organisms? DARWIN’S THEORY OF EVOLUTION Evolution — the process of change over time In Darwin’s travels aboard the HMS Beagle, which began in 1831, Charles Darwin made three important observations: The world includes a tremendous diversity of living things throughout a wide range of habitats Animal species, like those in the Galapagos Islands, that are related, can have different characteristics or occupy different habitats in the same area. Fossils — preserved remains of ancient organisms, resembled Darwin’s observations led him to develop the scientific theory of evolution which explains how modern organisms evolved over long periods of time by natural selection. Adaptation — a trait that helps an organism survive and reproduce. Natural selection — process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species. Factors that affect process of natural selection: Overproduction — species produce more offspring than one can survive (insects, fish) Variations — difference between individuals Competition — resources are limited, species must compete to survive Question: How Whatare is genetic fossils formed? drift? EVOLUTION THE FOSSIL OF POPULATIONS RECORD Paleontologists — scientist who studies fossils or the preserved remains traces of Genetically speaking, evolution is a change in the frequency of alleles in or a population organisms that have lived in the past. over time. Three sources of genetic variations: Fossil record — collections of fossils organized to provide evidence about history of life Mutations —on charge in including genetic material of cell have changed over time. Earth, how organisms Genetic Recombination — during sexual reproduction each chromosome in a pair moves independently during meiosis — in humans this can produce over 8,000,000,000 gene combinations geneoftransfer — passing ofcan genes from TheLateral formation fossils are rare but occur by:one organism to another (not including offspring) Petrified Fossils Molds and Casts Preserved Remains — remains are buried in — hollow space in sediment quickly buried organisms are Gene pool — consists of all genes, the differentpreserved alleles, that a sediment then change to in including the shape all of an by are ice,present volcanicinash population rock over time – now organism is called a mold; or clay before they begin to called petrified fossil when a mold becomes decay. filled with hardened minerals it becomes a Hardy — Weinberg principle — states that allele frequencies will remain constant or cast. have genetic equilibrium, unless factors cause those frequencies to change. The Hardy—Weinberg principle holds under these five conditions: Relative Dating Vs. Radioactive Dating 1. random mating Age of fossils is determined by comparing Involves measuring the amounts of 2. very large population its placement with that of fossils in other radioactive isotopes in a sample to 3. no in or out of population layers of movement rock. determine its actual age 4. no mutations 5. no natural selection Paleontologists use the geological time scale, or a “Calendar” of Earth’s history, to represent evolutionary time. Reproductive isolation, or when two populations no longer inter breed, can cause evolution of two separate species. This can time be caused bydivided behavioral geographic After Precambrian Time, the geological scale is intoisolation, eras (Paleozoic, isolation and temporal isolation. Mesozoic and Cenozoic) and those eras are subdivided into periods, which range in length from tens of millions of years to less than two million years. Question: What is taxonomy? CLASSIFICATION In the 1730’s, Carolus Linnaeus, a Swedish botanist, developed a two-word naming system called binomial nomenclature — first part of name is genus with second part of name referring to species. Linnaeus also developed a classification system which included seven hierarchal taxa: Ex. Grizzly Bear KINGDOM PHYLUM CLASS ORDER Animalia Chordata Mammalia Carnivora FAMILY GENUS SPECIES Ursidae Ursus Ursus Arctos Sometimes classification keys are used to identify organism by traits that are visible, however scientists today now look at how closely members of groups are related. Phylogeny — study of how living and extinct organisms are related to one another Clade — group of species that includes a single common ancestor and all descendants of that ancestor. Cladogram — diagram that links groups of organisms by showing how evolutionary lines, or lineages branched off from common ancestors. Derived Character — trait that arose in the most recent common ancestor of a particular lineage and passed to its decendants. Question: What broad characteristics do biologists use to group living things into kingdoms? DOMAINS AND KINGDOMS Organisms are placed into domains and kingdoms based on their cell type, their ability to make food, and the number of cells that make up their bodies. CLASSIFICATION OF LIVING THINGS DOMAIN KINGDOM CELL TYPE CELL STRUCTURES # OF CELLS MODE OF NUTRITION EXAMPLES Bacteria Eubacteria Prokaryote Archaea Archaebacteria Prokaryote Protista Fungi Eukarya Plantae Eukaryote Eukaryote Eukaryote ( lacks a nucleus ) ( lacks a nucleus ) Some cell Cell walls Cell walls walls of of of cellulose Cell walls Cell walls cellulose chitin with without PeptidePeptideSome Chloroglycan glycan chloroplasts plasts Most Most Most unicelmulticelmulticellular lular lular Unicellular Unicellular Some Some uni Some green colonial Algae uni Some multi AutoHeteroAutotroph Autotroph or Autotroph or troph or troph Heterotroph Heterotroph Heterotroph Amoeba, Mushroom Mosses, Slime Yeasts ferns, E. Coli Halophiles molds flowering plants Animalia Eukaryote No cell walls or chloroplasts Multicellular Heterotroph Sponges, norms, insects, fish, mammals