Evidence for Evolution By Bradley Grey Objectives Today

Evidence for Evolution By Bradley Grey

Objectives Today students will be able to describe evolution and discuss the evidence that supports it. Also, today students will be able to explain how natural selection works to drive evolution.

Kahoot. it Using your i. Pad go to- kahoot. it Answer the questions to the best of your ability. Follow the on screen instructions and enter the code given by your teacher.

In 90 seconds, draw this fish to the best of your ability with as many details as possible.

Blended Learning Groupings

EVIDENCE FOR EVOLUTION Scientific evidence to support the Theory of Evolution by Natural Selection

Honors Each student will research an example of one piece of evidence for evolution. Choices: fossil, anatomical, physiological, embryological, biochemical, and universal genetic code Research for 10 minutes and gather information to share the example with your group. Complete the guided note for homework. If you need a hard copy of the notes see me at the end of class.

FOSSIL EVIDENCE FOSSILS – are the mineralized remains or traces (tracks, imprints) of animals, plants or other organisms THE FOSSIL RECORD – fossils found in rock strata that show a sequence or history of life on Earth Trilobite fossil found in Burgess Shale

BURGESS SHALE FOSSILS The Burgess Shale is a middle Cambrian site (~540 MYA) One of the few places in the world where difficult-to-preserve soft-bodied organisms of our past were preserved Some of the fossils found here are now long extinct and are unlike anything presently existing

THE FOSSILS RECORD PROVIDES US WITH THE FOLLOWING EVIDENCE: Fossils found in young layers of rock (ie closer to the surface) tend to be more similar to present day organisms Fossils appear in chronological order (oldest ancestors in deepest layers Not all organisms appear in the fossil record at the same time – ie fish are the oldest vertebrates – then in subsequent layers amphibians, reptiles, mammals and birds Geologic Time Table

TRANSITIONAL FOSSILS Transitional fossils are fossils that show intermediary links between groups of organisms They can provide a link between the past and present Archaeopteryx – a transitional fossil because of its characteristics of both reptiles (dinosaurs) and birds

ARCHAEOPTERYX – transitional fossil

TRANSITIONAL FOSSILS EXAMPLES Example: Basilosaurus and Dorudon were ancient whales with tiny hind limbs – living entirely in water Ambulocetus – a more recent ancestor, had heavier leg bones and lived in both water and on land Fossil Comparisons

ANOTHER TRANSITIONAL FOSSILS: TIKTAALIK - The tiktaalik was an ancient tetrapod - It was thought to have descended from lobe-finned fishes -- They lived in oxygen-poor water - used their lobe fins to live partly on land-possibly gave rise to amphibians

BIOGEOGRAPHY – the study of the past and present geographical distribution of organisms. Darwin and Wallace observed that many species evolve in one location and spread out to other areas Darwin found 14 different species of finch – he theorized all evolved from one common ancestral finch Evolution Theorists ADAPTIVE RADIATION – Diversification of a common ancestral species into a variety of species

BIOGEOGRAPHY Close environments (ie desert & forest in South America) have more related species than geographically separate but environmentally similar locations (ie – desert in S. America, desert in Australia) Continent Comparisons -left: cactus from S. America -right: cactus from Australia

BIOGEOGRAPHY Animals found in islands often resemble animals found on closest islands – suggesting animals have evolved to suit new environment Example: lizards off NW coast of Africa (canary islands are similar to lizards in West Africa Continent Comparisons Top: Canary Island lizard Bottom: West African lizard

BIOGEOGRAPHY Fossils of the same species can be found on the coastline of neighboring continents Example: Cynognathus has been found in Africa and S. America At one time, all continents were joined (Pangea – 250 MYA) Future World-Earth -a depiction of the Earth 250 MYA – continents were joined together

Cynognathus – ancient reptile -distribution of ancient organisms Cynognathus crateronotus

Anatomical Evidence: HOMOLOGOUS STRUCTURES- Same structure different function Vertebrate forelimbs can be used for many different functions: Flying (birds, bats) Swimming (whales) Brachiation (monkeys) Running (horses, dogs) HOWEVER: they ALL contain the same set of bones organized in similar ways – WHY? Homologous structures are similar in structure but often differ in function

Homologous Structures - structures that share a common ancestry Why ? Structures are anatomically similar because they are modified versions of a structure that occurred in a common ancestor

HOMOLOGOUS STRUCTURES Homologous structures provide evidence for a common ancestor amongst all vertebrates

ANALOGOUS STRUCTURES Analogous Structures that evolve separately to perform a similar function are analogous. The wings of birds, bats, and insects, for example, have different embryological origins but are all designed for flight. • Bird: feathers • Bat: skin • Butterfly: chitin

VESTIGIAL STRUCTURES Vestigial structures are thought to have had a purpose at one time in our ancestry, but no longer have a specific function (eg) human appendix

VESTIGIAL STRUCTURES “c” indicates the Underdeveloped hind legs Of the baleen whale The muscles connected to the ear of a human do not develop enough to have the same mobility as those of the monkey

Developmental Patterns Similar development of embryos between many species (humans and all other ) Shows process of development has evolved

EMBRYOLOGY The embryos of different vertebrates show similar stages of embryonic development Neck pouches – in humans become ears & throat - in fish become gills - Similarities among embryos point to a common ancestor

EMBRYOLOGY Can you tell which embryo is which? A – cat B – cow C - horse D - human

Biochemical Evidence: DNA and Proteins Organisms traits are encoded in DNA; the more similar 2 species, more similar DNA proteins made from DNA Gel comparison Protein comparison

MOLECULAR BIOLOGY & GENETICS Many organisms share similar cellular components such as: Proteins – long chains of amino acids used for building & repair Enzymes – made from proteins – they control many biochemical reactions in the cell DNA – genetic material found in the nucleus The DNA of chimpanzees & humans is ~ 98% identical

HEMOGLOBIN Hemoglobin—the oxygen-transport protein that gives blood its red color—got its start at about the time life originated on earth, nearly four billion years ago. Now it is almost ubiquitous, appearing in the cells of plants, animals and even bacteria, and a study of this protein affords scientists a rare glimpse back as well as forward in time. A look at the ancestral hemoglobins indicates that newly arising proteins co-opt the chemistry of older ones and gain new functions through structural alterations. But these studies have revealed an additional way to modify function. Scientists are coming to the realization that changes in a protein's regulation—the when and how of its expression—can also give rise to functional differences. The surprise, says the author, is that these regulatory changes outpace structural ones—an important lesson for students of molecular evolution and a possible indicator of where protein evolution will go in the future. http: //adsabs. harvard. edu/abs/1999 Am Sci. . 87. . . H hemoglobin (found in RBCs) is used to bond to O 2

EVOLUTION: the change in the inherited traits of a population from generation to generation Above: hominid evolution

Reflection Questions How are inherited characteristics transmitted from 1 generation to the next? Why are inherited characteristics not blended out, but can disappear and reappear in later genetics? How do the variations arise on which natural selection acts?