SB5C. Explain how fossil and biochemical evidence support the theory Evidence of Evolution (15.2) State Standard SB5C. Explain how fossil and biochemical evidence support the theory

Chapter 15 Evolution 15.2 Evidence of Evolution The Fossil Record Fossils provide a partial record of species that lived long ago. Only the harder parts of an organism are likely to leave fossils – ex: shells, bones, thick cell walls. Very few fossils capture the details of skin or internal organs. Sometimes impressions are left behind in sediments along rivers and lakes.

The Fossil Record cont’d Chapter 15 Evolution 15.2 Evidence of Evolution The Fossil Record cont’d Fossils show that ancient species share similarities with species that now live on Earth. One problem w/ the fossil record is the lack of “intermediate” or transition forms. This could be due to many organisms being too soft or due to fossils being destroyed by the erosion or pressure. Glyptodont Armadillo

Fossils Cont’d Otzi the Iceman

Fossils Cont’d

Determining Fossil Age Chapter 15 Evolution 15.2 Evidence of Evolution Determining Fossil Age Biologists use radioisotope (radiometric) dating to determine the approximate age of fossils. The isotopes act as clocks for measuring time. To use this method, scientists must know: 1. The half-life of the isotope being measured. 2. how much of the isotope was originally present in the fossil or in the rock containing the fossil. 3. how much of the isotope is left.. Half-life is the amount of time it takes for half of the isotope to decay.

Determining Fossil Age Cont’d Chapter 15 Evolution 15.2 Evidence of Evolution Determining Fossil Age Cont’d Biologists most often use Carbon 14 for radioisotope dating, but its half-life is relatively short. Other isotopes like Uraniaum 235 are often used to help determine the age of older fossils. Relative dating determines the relative age of rocks/fossils by comparing them to known older or younger layers.

Comparative Biochemistry Chapter 15 Evolution 15.2 Evidence of Evolution Comparative Biochemistry Common ancestry can be seen in the complex metabolic molecules that many different organisms share.

Chapter 15 Evolution 15.2 Evidence of Evolution Comparative Biochemistry Cont’d Comparisons of the similarities in these molecules across species reflect evolutionary patterns seen in comparative anatomy and in the fossil record. Organisms with closely related morphological features have more closely related molecular features.

Chapter 15 Evolution 15.2 Evidence of Evolution Comparative Embryology Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms. Many scientists believe this is evidence that all vertebrates share a common ancestor.

Homologous Structures Chapter 15 Evolution 15.2 Evidence of Evolution Anatomical Evidence Homologous Structures Anatomically similar structures that may or may not have the same function. Indicate possible common ancestry

Anatomical Evidence Analogous Structures Chapter 15 Evolution 15.2 Evidence of Evolution Anatomical Evidence Analogous Structures Similar in function but not in construction so they do not indicate shared ancestry Show that functionally similar features can evolve independently in similar environments

predicts that features of ancestors that no Chapter 15 Evolution 15.2 Evidence of Evolution Anatomical Evidence Vestigial Structures Structures that are the reduced forms of functional structures in other organisms. Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost.

Anatomical Evidence Vestigial Structures Cont’d

Chapter 15 Evolution 15.2 Evidence of Evolution Anatomical Evidence Adaptations An adaptation is an inherited trait that may increase an organism’s survival and reproductive success. Fitness is a measure of the relative contribution an individual trait makes to the next generation.

Allows organisms to become almost invisible to predators Chapter 15 Evolution Anatomical Evidence Adaptations Cont’d Camouflage Allows organisms to become almost invisible to predators All about hiding Leafy sea dragon

Camouflage Cont’d

Camouflage Cont’d

One species evolves to resemble another species. Chapter 15 Evolution Anatomical Evidence Adaptations Cont’d Mimicry One species evolves to resemble another species. All about scaring/warning (not hiding). Western coral snake California kingsnake

Mimicry Cont’d

Chapter 15 Evolution 15.2 Evidence of Evolution Geographic Distribution The distribution of plants and animals that Darwin saw first suggested evolution to Darwin. Rabbit Mara

The Mara & Rabbit fill the same niche on 2 different continents. Chapter 15 Evolution 15.2 Evidence of Evolution Geographic Distribution Cont’d The Mara & Rabbit fill the same niche on 2 different continents. Darwin observed that the Mara was more similar to other South American species than it was to the rabbit, and vice versa. Mara Rabbit

Chapter 15 Evolution 15.2 Evidence of Evolution A phylogeny is a description of the line of descent of a group of organisms. Fossil collections are often not complete enough to determine any evolutionary patterns or traits, so biologists will infer likely phylogenies by comparing morphological features, DNA sequences, and chromosomal characteristics. Extinction is the permanent loss of a species. Phylogenetic Trees

Chapter 15 Evolution 15.2 Evidence of Evolution Types of Characters (traits) Derived traits are newly evolved features, such as feathers, that do not appear in the fossils of common ancestors. Ancestral traits are more primitive features, such as teeth and tails, that do appear in ancestral forms.

Cladogram - a diagram showing possible relationships between organisms based on shared traits (characters)

How to Read – if the organism is above the trait, it has the trait How to Read – if the organism is above the trait, it has the trait. If it is below the trait, it doesn’t have it.

Ancestral Character – shared by all species on the diagram. Derived Character- only shared by some Outgroup – least in common

Homologous or Analogous? Bat Wing Human Arm

Homologous or Analogous? Bat Wing Bird Wing

Homologous or Analogous? Dragonfly Wing Hummingbird Wing

Homologous or Analogous? Dragonfly Wing Bumblebee Wing

Identify the term that is used to describe Chapter 15 Evolution Chapter Diagnostic Questions Identify the term that is used to describe anatomically similar structures inherited from a common ancestor. ancestral traits analogous structures homologous structures vestigial structures A B C D CDQ 2

Which is not a vestigial structure? Chapter 15 Evolution Chapter Diagnostic Questions Which is not a vestigial structure? snake pelvis Kiwi wings porpoise flipper human appendix A B C D Kiwi Bird CDQ 3

Which is an example of a derived trait? Chapter 15 Evolution 15.2 Formative Questions Which is an example of a derived trait? a tail bones feathers teeth A B C D FQ 6

Which features are similar in use and evolve in Chapter 15 Evolution 15.2 Formative Questions Which features are similar in use and evolve in similar environments, but do not evolve from a common ancestor? analogous structures embryological structures homologous structures vestigial structures A B C D FQ 7

Organisms with similar anatomy share similar DNA sequences. Chapter 15 Evolution 15.2 Formative Questions Organisms with similar anatomy share similar DNA sequences. True False A B FQ 8

At the heart of the theory of evolution by natural Chapter 15 Evolution 15.2 Formative Questions At the heart of the theory of evolution by natural selection lies the concept of __________. adaptation biogeography gradualism speciation A B C D FQ 9

Standardized Test Practice Chapter 15 Evolution Standardized Test Practice Which is the best explanation for the similarities in the construction of these forelimbs? Each forelimb is a similar modification derived from a different ancestor. Natural selection has produced similar modifications in the forelimb. They are functionally similar features that have evolved independently. They are modifications of the forelimbs of a common ancestor. A B C D STP 2

Standardized Test Practice Chapter 15 Evolution Standardized Test Practice Predators learn to avoid monarch butterflies because they contain a poison that is distasteful and can cause the predator to get sick. The viceroy butterfly finds protection by closely resembling the monarch. What is this adaptation in the viceroy called? camouflage fitness mimicry resemblance A B C D STP 3