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Name:________________________ Date:_________________________ Lesson # 2: Evolution (Evidence for Evolution) Evidence Supporting Theories of Evolution - We will look at major evidence supporting theories of evolution: 1) Fossil Record 2) Comparative Anatomy 3) Biogeography 4) Biochemistry Fossil Record Fossil Definition Any __________ ____remains, impressions, or traces of an organism or traces of its activity that have been _________________ in rocks or other mineral deposits in Earth’s crust Hard _____________________ in solid rock and leave little doubt as to what they represent Fossil Formation Fossils are formed when the remains of a ________________organism are gradually replaced by _________________deposits Once a body dies the body usually ___________________ When ____________________accumulate over time the body becomes compressed, and gradual chemical changes occur that result in the body being mineralized Only organisms that die in _____________________locations will fossilize Organisms with ___________ body parts (shells, bones, teeth) are more likely to be preserved Fossils of aquatic organisms are very common rather than fossils of ________animals and ___________ ______________fossils are well known but very rare compared to those of aquatic organisms Fossils can also be formed from _______________and burrows Organisms can also become trapped in materials that _____________its chemical remains i.e. tree sap, volcanic ash, permafrost, acidic bogs Name:________________________ Date:_________________________ Reading the Fossil Record Paleontology The scientific investigation of ________________ life through the study of fossils Discoveries about fossils: 1) Many fossils appear to be of _____________and unknown organisms 2) There are no fossils of most _____________species 3) Fossils are often buried very deep within ___________________________ 4) Fossils are often found in _________________ locations (i.e. fossils of sea life are found high in mountain formations in present – day deserts) These contradicted prior views that fossils were nothing more than organisms that had become trapped in muddy deposits and then hardened Georges Cuvier Conducted the first detailed studies of fossils Noted the following: Fossils are very simple organisms are found in all depths of fossil ______________ Fossils of more _____________organisms are found only at _________________depths, in younger rock Fossils in the shallower depths are more likely to _____________living species Rock layers contain fossils of many species that do not occur in _________above or below them How Fossils Support Theory of Evolution Life had evolved from ____________to more complex forms over time Species themselves do not change, instead theory of catastrophism Catastrophism The theory that the _______________of fossils could be accounted for by a series of global catastrophes that wiped out most species on Earth Cuvier discovered that different groups of species get more complex in each younger layer but not why this happened Recall Lyell Name:________________________ Date:_________________________ Proposed that Earth’s geological features can be explained by very slow ___________ occurring over very long periods of time Darwin’s Hypothesis Theory that species ___________ Hypothesized that remote oceanic islands became __________________by species that arrived by water or air After the species became established, many evolved into new species over time “Tree Thinking” Implies that all organisms are related According to the principle of common ____________, all species living or extinct are descended from common ____________ Darwin’s Hypothesis Regarding Remote Islands Observations on Galapagos Islands Darwin’s Hypothesis Many species of plants, birds, insects and in some cases reptiles Only these kinds of organisms are able to reach remote islands by crossing large expanses of open ocean No native amphibians and very few land mammals Amphibians and most mammals are unable to cross open ocean and will not be found on remote islands Many unique species found nowhere else on Earth Over time, ancestral species have evolved into new geographically isolated species Unique species most closely resemble species on the nearest continental land mass Unique species are descendants of ancestral species from the nearest continental land masses and will exhibit some similarities Comparative Anatomy (Homologous Features) ___________________Feature A structure with a common evolutionary origin that may serve different _____________in modern species i.e. bat wing and human arm Similar structures of two organisms could have entirely different functions Name:________________________ Date:_________________________ Similar in ___________ ______________ in function May appear in embryonic development and disappear before birth Existence of homologous structures adapted to different purposes as a result of descent with modification from a common ancestor Comparative Anatomy (Analogous Features) __________________Feature A structure that performs the same function as another but is not similar in origin or anatomical ________________ i.e. wing of bee and wing of bird ______________ in origin Similar in _______________ May appear in embryonic development and disappear before birth Comparative Anatomy (Vestigial Features) Vestigial Features A rudimentary and ____________________, or only marginally functioning, structure that is homologous to a fully functioning structure in closely related species i.e. hipbones of bottleneck dolphins Relation to Evolution Features that in an ancestor had once served a _____________ purpose had become ____________ or greatly distorted as the species evolved Biogeography Biogeography The scientific study of the _______________ distribution of organisms based on both living species and fossils Darwin’s Discoveries Looked at __________ on the Galapagos islands Populations on islands evolved from ________________ species Name:________________________ Date:_________________________ Natural selection on islands produced _________________ among populations (resulting in different but closely related island species) __________ depth, and the ability to crack larger seeds, varies according to drought conditions, which produce fewer, harder seeds in dry years and more and softer seeds in wet years Consistent environmental differences in different habitats on different islands in the Galapagos, as well as the ____________________ of different foods sources, have produced more than a dozen distinct ____________ of finches, all unique to the archipelago. Biochemistry Genetic and Molecular Biology Some of the most crucial evidence comes from ____________ At the molecular level, universal genetic _______ and homologous molecules provide evidence of common descent Also, _________________ and reshuffling of genes during sexual reproduction produce heritable variation on which natural selection operates
