Ch. 6.3 Biological Evidence of Evolution

Ch. 6.3 Evidence of Evolution foldable:

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– Homologous structures

– Analogous structures

– Vestigial structures

– Developmental biology (embryology)

– Comparing DNA sequences

– Divergence

• On inside of tabs:– Description

– How it supports theory of evolution

Lesson 1-5

• As 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?

• Comparative Anatomy – the study of similarities and differences among structures of living species.

• Homologous Structures – body parts are similar in structure, but different in function

Comparative Anatomy

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)

Analogous structures: Body parts are similar in function, but different in structure (not closely related)

(ex: bird wings vs. insect wings)

Comparative Anatomy

Evidence: Differences in structures =

species are not related

What term refers to body parts of organisms

that are similar in structure and position but

different in function?

A. B. C. D.

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A. Camouflage

B. Mimicry

C. Analogous structures

D. Homologous structures

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Vestigial structures are body parts that have lost their original function through evolution.

Comparative Anatomy

Section 1 Change over Time

Evidence: shows relation to ancestors who

used the part for a specific purpose

Which of the following is NOT evidence that

whales evolved from mammals that once

lived on land?

A. B. C. D.

0 000

A. fossil discoveries that link

whales to mammals

B. the hip bones of whales

C. the fishlike shape of whales

D. the fact that whales are

mammals

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Studying 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 birth

Evidence: similarities in development of parts show relatedness

Developmental Biology

All 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)

2. How are Earth’s organisms related?

Rat Chicken Human

http://www.pbs.org/wgbh/evolution/library/04/2/quicktime/l_042_02.html

What term refers to body parts that perform

a similar function but differ in structure?

A. B. C. D.

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A. Analogous structures

B. Homologous structures

C. Pharyngeal pouches

D. Vestigial pelvis

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• Molecular 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 Biology

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 species

Divergence: Using the rate of DNA mutations (“molecular clock”) to estimate when species changed

Molecular data indicate that whales and porpoises are more closely related to hippopotamuses than they are to any other living species.

Molecular Biology

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Evidence: shows how closely related

species are to each other

When was the last time Whales and Even-

toed hoofed mammals shared a common

ancestor?

0%

0%

0%

0% A. 35 mya

B. 50 mya

C. 65 mya

D. 75 mya

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2 Views on the rate of natural selection:

A. slowly and steadily

B. change occurs in short bursts after long

periods of stability.

• The 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 Darwin’s basic principles still hold true after 150+ years.

What evidence suggests that humans are

more closely related to chimpanzees than

any other animal?

A. B. C. D.

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A. Analogous structures

B. Homologous structures

C. DNA sequences

D. Vestigial structures

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