I can explain how - PowerPoint Presentation

Slide1

I can explain how

The fossil recordAnatomical, embryological, cellular and molecular similaritiesArtificial selection

can be used as evidence for the evolutionary development of a given speciesSlide2

HS‑LS4‑1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.

Fossil record (transitional species, evidence of past life and environments)anatomical structures (structural similarities, homologous structures)

appearance of structures in embryological development.]

similarities in DNA sequences (molecular similarities)Slide3

Evidence: the fossil record

Remember when we looked at the fossils?

Fossils provide evidence of past lifeSlide4

Transitional species found in fossil record

fish –amphibian (Tiktaalik fossil)Slide5

Transitional fossils:

bird/reptileArchaeopteryxJ-park scene: comparing dinosaur fossils to modern day birdsSlide6

Vestigial legs in dolphins foundSlide7

Evidence: structural similarities

(a.k.a. homologies/homologous structures)

1. Homologies

Evolutionary theory predicts that related organisms will share similarities that are derived from common ancestors.

Similar characteristics due to relatedness are known as homologies.

Homologies can be revealed by comparing the anatomical structures of different living things, studying embryological development in different organisms, cellular similarities and molecular (especially DNA) similarities between organisms.Slide8

Spines, flowers, insect –catching traps and pits are all modified ______________________?

What function do the modified leaves serve for each of the 4 types of plants?Slide9

Another example of homology is the forelimb of tetra pods (vertebrates with legs).

Humans, cats, whales and bats all have different forelimbs, reflecting their different lifestyles. But those different forelimbs all share the

same bone elements

- the humorous, the radius, ulna and other

bone elements in common

. Slide10

Some of the most interesting homologous structures are

vestigial structures

, structures of little, if any importance to current organisms. Vestigial structures are

organs or structures remaining or surviving in a degenerate, or imperfect condition or form.

Vestigial pelvis and legsSlide11

Snakes have legged ancestors.

Some species of living snakes have hind limb-buds as early embryos but rapidly lose the buds and develop into legless adults. The study of developmental stages of snakes, combined with fossil evidence of snakes with hind limbs, supports the hypothesis that snakes evolved from a limbed ancestor.

Photo to the left, the Cretaceous snake 

Pachyrhachis

problematicus

 clearly had small

hindlimbs

. The drawing at right shows a reconstruction of the pelvis and

hindlimb

of 

Pachyrhachis

.Slide12

What are some other examples of vestigial structures?Slide13

Figure 2.1.1. Vestigial structures of various organisms. From top to bottom: A. A hypocritical ostrich with its wings extended. B. A blind cave salamander - look closely for the eyes buried underneath the skin. C.

Astyanax

mexicanus

, the Mexican tetra, a blind cave fish.

Slide14

Vestigial legs in dolphins foundSlide15

Vestigial structures in humans?Slide16
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Charles Darwin listed a number of putative 

human vestigial features, which he termed rudimentary, in The Descent of Man (1890). These included Slide18

Evidence:

embryological similaritiesSlide19

Embryological similarities

Darwin saw that embryonic resemblances would be a very strong argument in favor of the genetic connectedness of different animal groups

. Slide20

What species is this????Slide21
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Ultimately: the body form of an organism is controlled by its DNA (genes) – stay tuned



(

Hox

genes)Slide23
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Homologies: at the cellular level

All living things are fundamentally alike.

At the cellular level living things are remarkably similar to each other. These 

fundamental

 similarities are most easily explained by evolutionary theory: life shares a common ancestor.

What cellular structures are shared by all eukaryotic organisms?Slide25
Slide26

Evidence: homologies at the molecular level

What genetic code is shared by all species?Slide27

DNA!!

(bonus link)Slide28

The molecular level (cont)

In fact, the DNA code itself is a homology that links all life on Earth to a common ancestor. DNA and RNA possess a simple four-base code that provides the recipe for all living things. In some cases, if we were to transfer genetic material from the cell of one living thing to the cell of another, the recipient would follow the new instructions as if they were its own.

These characteristics of life demonstrate the fundamental sameness of all living things on Earth and serve as the basis of today's efforts at genetic engineering.Slide29

GFP traditionally refers to the protein first isolated from a gene found in the 

jellyfish Aequorea victoria

which glows in the dark.

The GFP gene can be transferred to other organisms which will express this same trait.Slide30

GloFish

, the first genetically modified animal to be sold as a petSlide31

Genomic comparison evidence

Comparative genomics is a field of biological research in which the genome sequences of different species — human, mouse, and a wide variety of other organisms from bacteria to chimpanzees — are compared. genomic comparisons article

Protein comparisonSlide32

By comparing the sequences of genomes of different organisms, researchers can understand what, at the molecular level, distinguishes different life forms from each other.

Comparative genomics also provides a powerful tool for studying evolutionary changes among organisms, helping to identify genes that are conserved or common among species, as well as genes that give each organism its unique characteristics. Fossil genes????

Activity : HHMI- Ice fish (link)Slide33

The genetic similarities among organismsSlide34

Back to index Slide35

Evidence:

the pattern of organism groupings.

Classifying life based on evolutionary relatednessSlide36
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Evidence: The direct observation of evolutionary changes in the laboratory and in the wild.

Darwin’s views on the role of environmental factors in the screening of heritable variation was heavily influenced by

artificial selection

.

Humans have modified a variety of domesticated plants and animals over many generations by selecting individuals with the desired traits as breeding stock.Slide38
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The domestication of corn (a somewhat corny example)

http://www.hhmi.org/biointeractive/breeding-corn-teosinteSlide40

artificial selection- dogs Slide41

Want to learn more????

Here are some great sites to check out!!Understanding evolution (UC Berkeley)

:http://evolution.berkeley.edu/

PBS Evolution site:

http://www.pbs.org/wgbh/evolution/

The Complete Work of Charles Darwin Online

:

http://www.topsite.com/goto/darwin-online.org.uk

The American Association for the Advancement of Science:

http://www.aaas.org/news/press_room/evolution/

The National Science Foundation:

http://www.nsf.gov/news/special_reports/darwin/home.jsp

Science Daily- current findings in evolutionary biology:

http://www.sciencedaily.com/news/fossils_ruins/evolution/

Nature:

http://www.nature.com/nature/supplements/insights/evolution/

Howard Hughes Medical Institute

http://www.hhmi.org/biointeractive/browse?field_bio_format_type%5B0%5D=23448&field_bio_biointeractive_topics%5B1%5D=23477Slide42

I can explain how

the fossil recordanatomical, embryological, cellular and molecular similarities and artificial selection

can be used as evidence for the evolutionary development of a given species