The Evolving Nature of Life Ms. Johnson Ms. Doncaster Biology – Level 4
Standards • SC.NL.04.01 • Describes how the biochemical and physical nature of the earth determines how life evolves. • SC.NL.04.02 • Uses the Darwinian theory to explain how organisms must adapt to survive. • SC.NL.04.03 • Describes the theory that life has evolved from simple to more complex forms and that evolution is an ongoing process.
Fact –OR- Fiction • Lizards are more closely related to birds than crocodiles. • FACT. Genetically more similar to a bird!
Fact –OR- Fiction • In a healthy population, everyone has the same genes. • FICTION. Variety can be a result of mutations, which can be key to a population’s survival
Fact –OR- Fiction • Panda bears are NOT bears. • FACT & FICTION. Most scientists classify the giant panda as a bear, but the red panda actually a type of raccoon.
Fact –OR- Fiction • Dragonflies were once as large as pigeons. • FACT. Fossils reveal that giant dragonflies inhabited earth 290 million years ago.
Fossils, Etc. Ms. Johnson Ms. Doncaster Biology – Level 4
SC.NL.04.01 • Describes how the biochemical and physical nature of the earth determines how life evolves.
Hmmm… • Biodiversity - variety and abundance of diff’t species in a community. • Change can create advantages/disadvantages • Nat’l Disaster: Those who adapt better (more traits), more likely to survive
Numbers • Current # of species: 5-30million (only a fraction of what once was…) • 99% of all organisms ever, now extinct • Life – 4 billion years
Where did all the mammals go? • Evolved 200mil yrs ago • Who studies fossils? • Paleontologist • How are fossils studied? • Anatomical, Molecular, Biogeographical
Fossil Vocab • Fossil record – information stored in fossils • T/F Are all fossils bones? • Fossils found in sedimentary rock (sand/silt settled at bottom of body of water) • Compressed • Water becomes dry land • Fossils hard to find, vulnerable to weather and erosion
Basilosaurus • In the middle of the Sahara, hundreds of whale skeletons • Keep digging…Basilosaurus had legs!! • Now in search of transitional fossils (fossils between related fossils)
Transitional Fossils • Hard to find • Most DON’T lead to common ancestor, but to “close cousins”
Vocab • Homologous structures • Different species, same characteristics • Ex: Front fin of a whale (humerus, radius, ulna) • Also found in other mammals: humans, wolves, sea lions • Sequencing • DNA base or amino acid • Molecular biologist compare proteins
Vocab • Vestigial structures • Inherited, but size reduced and often unused • Ex) Pythons (hip/leg bones) • Ex) Humans (appendix) • Analogous structures • Same function, different structures • Ex) Bat, Bird, Insect • WINGS!!
Vocab • Phylogeny – History of an organism’s development • What current mammal is most closely related to the whale? • Yeah!!! Hippopotamus!!!
Fossil Dating • Relative Dating • Radiometric Dating
Relative Dating • Older deposits found beneath more recent • Geologic layers (with no/little geologic activity) • Two fossils. Same layer, ∴ Same time period
Relative Dating • Rock layers do not determine age, but serves to put layers in order of age • Real age estimated by analyzing isotopes of surrounding rocks
Radiometric Dating • Isotope: Single atoms of same element with different # of neutrons • Weight changed • Charge unchanged • Some isotopes “radioactive” • During decay, isotopes give off particles and energy
Radiometric Dating • Radioactive isotopes break down (decay) matter at a constant rate • Rates of decay: half-lives • Half-live: the time it takes for ½ of the original isotope to decay into a different isotope • *Note* Every isotope has a different, but known rate
Radiometric Dating – Half-Life • 40K decays to Ar • 40K half-life is 1.3bil years!!
Radiometric Dating • Oldest fossil: ancient prokaryote • Purpose: construct an evolutionary timeline
Eras, Periods, Epochs • Remember…Life – 4 billion years • Divided into Eras periods epochs • Defined by fossil finds!!
Eras, Periods, Epochs • Precambrian Era (590mil yrs ago) • Paleozoic Era (248-590mil yrs ago) • 6 periods… • Mesozoic Era (65-248mil yrs ago) • Triassic Period • Jurassic Period • Cretaceous Period • Cenozoic Era (0.01-65mil yrs ago)
Standard 1 Is history…
SC.NL.04.02 Uses the Darwinian theory to explain how organisms must adapt to survive.
SC.NL.04.02 – Species • Species are unique • Species: interbreeding populations
SC.NL.04.02 – Variation • Within a species’ is a good amount of variation • Variation: differences between individuals in a population • Subtle/Dramatic - (color, communication, shape of teeth, number of offspring, territory size, diet)
SC.NL.04.02 – Variation • Most variations are genetic • Mutation • Change in gene sequence • Ex: Red fox becomes silver • Recombination • Allele from “Mom” mixes with allele from “Dad”
SC.NL.04.02 – Adaptation • Sometimes traits can be harmful • Inherited traits will determine SURVIVAL • Sometimes traits can be beneficial • ADAPTATION (increases survival rate)
SC.NL.04.02 – Adaptation • Ex: Termites, Anteaters • Small area, large population (termites) • Competition: two populations trying to occupy the same niche
SC.NL.04.02 – Adaptation • Become suited to a certain niche • Niche: Role a population plays in an environment • Live? Eat? Raise Offspring? Predators? Temp?
SC.NL.04.02 – Mr. Darwin & Co. • 1769 Charles Bonnet • Fossils didn’t look like modern lifeforms • Catastrophes must have affected earth, and life began again • Coined the term “evolution” (change over time) Notes: • Bonnet, earth catastrophes, “evolution”
SC.NL.04.02 – Mr. Darwin & Co. • 1809 Jean-Baptiste Lamarck • Challenged Bonnet • Fossils were ancestors of modern life • Organisms strive for improvement • Principle of Use/Disuse • Only useful parts passed on (Sorry Lamarck, your principle later disproved by mice) Notes: Lamarck, Principle of Use DISproved!
SC.NL.04.02 – Mr. Darwin • 1831 Darwin travels on HMS Beagle • Studies plants/animals around the world • Esp. Finches (diff groups had own niche) • Later, YES, really were 13 species
SC.NL.04.02 – Mr. Darwin • 1844 Thee Paper of All Papers! • 1858 Finally published (scared to publish) • On the Origin of Species by Means of Natural Selection
SC.NL.04.02 – Natural Selection • Variation w/in populations • Traits passed, but no info on genetics yet • Some variations are favorable • Improves organism’s function and reproduction • Ex) Fast ostriches outrun predators
SC.NL.04.02 – Natural Selection • Not all young produced in each generation can survive • Disease, starvation, predators • Individuals that survive and reproduce are those with favorable variations
SC.NL.04.02 – Natural Selection • Natural selection ultimately results in evolution • Gradualism: small genetic changes occurring over time • (But shouldn’t we see this in fossils?) • Punctuated Equilibrium: quick change b/c of environment, etc.
SC.NL.04.02 Conflicting Theories Help to Drive Research about Evolution
SC.NL.04.03 – Simple to Complex • Krakatoa- • Volcano – 1883 • Destroyed island, left only ash • No other land for 40km • Now has new plants/animals…
SC.NL.04.03 – Speciation • Evolution – process by which populations change in response to their environment • Sometimes organisms change so much that they can’t interbreed with the ancestor species, this means it IS a new species!!! -SPECIATION-
SC.NL.04.03 – Speciation • New species come when separated from original population (i.e. by geography) • They adapt (and biologically change) to the new environment
SC.NL.04.03 – Types of Evolution • 3 Types of Evolution • Divergent • Convergent • Coevolution
SC.NL.04.03 – Divergent Evolution • Same species evolve independently • Ex. by geography • or small group leaves the herd • Ex. Brown bears migrated to ice, adapted to become polar bears • Remember…According to natural selection, the animals with the advantageous traits survived and passed them on to offspring.
SC.NL.04.03 – Convergent Evolution • Unrelated species display similar features • Can mislead scientists to think animals are more similar than genetically are • Cross-check with embryology, biochemistry
SC.NL.04.03 – Convergent Evolution • Serval Cat vs. Maned Wolf • Both have: • Long ears to hear prey • Eat rodents, lizards • Long legs for chasing