Ch. 6.3 Evidence of Evolution

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Transcript of Ch. 6.3 Evidence of Evolution

MS Science

Ch. 6.3 Evidence of Evolution foldable:Create 6-tab foldableLabel front of tabs at top:Homologous structuresAnalogous structuresVestigial structuresDevelopmental biology (embryology)Comparing DNA sequencesDivergenceOn inside of tabs:DescriptionHow it supports theory of evolution Lesson 1-5As fossils were discovered, patterns emerged that showed many different species with similar body structures.Evidence suggests that species change over time. Change over time = Evolution (to evolve)Biological evolution is the change over time in populations of related organisms.What causes species to change over time?4Lesson 1-5

The fossil record is evidence that horses descended from organisms for which only fossils exist todayThe degree to which species are related depends on how closely in time they diverged, or split, from their common ancestor.


Lesson 3-1

Although the fossil record is incomplete, it contains many examples of fossil sequences showing close ancestral relationships. The fossil record indicates that different species of horses often overlapped with each other not in a series of orderly steps.6 How do we know evolution happens?

Lesson 3-1Comparative Anatomy the study of similarities and differences among structures of living species.Homologous Structures body parts are similar in structure, but different in functionComparative Anatomy

8Lesson 3-1

The forelimbs of these species are different sizes, but their placement and structure suggest common ancestry.Evidence: More similar structures = more related species (evolved from common ancestor)


Lesson 3-1Analogous structures: Body parts are similar in function, but different in structure (not closely related)(ex: bird wings vs. insect wings)Comparative Anatomy10

Evidence: Differences in structures = species are not related11What term refers to body parts of organisms that are similar in structure and position but different in function?

CamouflageMimicryAnalogous structuresHomologous structures45


Lesson 3-1Vestigial structures are body parts that have lost their original function through evolution.Comparative Anatomy13

Section 1 Change over Time

Evidence: shows relation to ancestors who used the part for a specific purposeWhich of the following is NOT evidence that whales evolved from mammals that once lived on land?

fossil discoveries that link whales to mammalsthe hip bones of whalesthe fishlike shape of whalesthe fact that whales are mammals45

Lesson 3-1Studying the development of embryos can also provide scientists with evidence that certain species are related.Embryology The science of the development of embryos from fertilization to birthEvidence: similarities in development of parts show relatednessDevelopmental Biology17Lesson 3-1All vertebrate embryos exhibit pharyngeal pouches at a certain stage of their development. In reptiles, birds, & humans, pharyngeal pouches develop into a gland in the neck in fish, they form gills. (both glands & gills regulate calcium)

How are Earths organisms related?18


20What term refers to body parts that perform a similar function but differ in structure?

Analogous structuresHomologous structuresPharyngeal pouchesVestigial pelvis

4521Lesson 3-1Molecular biology is the study of gene structure and function.Discoveries in molecular biology have confirmed and extended much of the data already collected about the theory of evolution.Comparing DNA Sequences: Scientists compare the similarity of genes (DNA) & proteins to study the relatedness of living species.Molecular Biology22

Aligned DNA fragment and first chromosome banding patterns for man (Homo sapiens), chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla), and orangutan (Pongo pygmaeus).Evidence: the more similar the DNA is, the more related the speciesHuman genes are 96% similar to chimpanzees and 85% similar to mice. Theres a gene (FOXP2 gene) that controls speech development in people (learning how to move our mouths & tongues to produce speech), song in birds, and learning sequences of rapid movement for mice.23

Lesson 3-1Divergence: Using the rate of DNA mutations (molecular clock) to estimate when species changedMolecular data indicate that whales and porpoises are more closely related to hippopotamuses than they are to any other living species.

Molecular Biology

~55Evidence: shows how closely related species are to each other25When was the last time Whales and Even-toed hoofed mammals shared a common ancestor?

35 mya50 mya65 mya75 mya45

26Lesson 3-22 Views on the rate of natural selection:slowly and steadilychange occurs in short bursts after long periods of stability.

27Lesson 3-2The fossil record is still incomplete, but new fossils are being discovered all the time.For example, the Tiktaalik fossil has both fish and amphibian features linking the 2.Most evolution research is now done at the molecular level, but Darwins basic principles still hold true after 150+ years.

28What evidence suggests that humans are more closely related to chimpanzees than any other animal?

Analogous structuresHomologous structuresDNA sequencesVestigial structures