Common Ancestry and Evidence for it

Common Ancestry and Evidence for it

E09 - TSWs 6 and 7​

Evogeneao: The Tree of Life

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What scientific understanding was needed?

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What evidence was collected to produce the tree of life?

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​How was the tree of life produced?

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Background Information

Evolution

Is the process of biological change by which populations become different from their ancestors. E.g. Modern humans (homo sapiens) evolved from earlier homonids, like homo erectus

Background Information

Common Ancestor

An ancient species from which two or more species evolved

​e.g. modern humans and chimpanzees share a relatively recent common ancestor

It is believed that all modern vertebrates evolved from a fish like creature.

Multiple Choice

Which two organisms share the closest common ancestor?

• Corals and Trees

• Bees and Birds

• Humans and Butterflies

• Lions and Tigers

Open Ended

What do you think is a whales closest living relative? (By whale, I mean all cetaceans, which includes dolphins, whales and porpoises)

Scientists use evidence, including body structures, genetic evidence and embryological development to support this hypothesis

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Whales are most closely related to Hippos!

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Evidence of Evolutionary Relationships

Common Ancestry

Many four legged, vertebrates have similar leg structures that carry out similar functions and evolved at similar times

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These are called homologous structures - they hint at evolutionary relationships​

Some structures perform similar functions but evolved separately - they are analogous structures. Organisms that share them are not closely related

​Similarities in Anatomy

Multiple Choice

Which of the following structures are homologous

• bird wings and bat wings

• human hair and spider hair

• human teeth and dog teeth

• Insect eyes and fish eyes

Multiple Choice

Which of the following structures are analogous?

• Octopus eyes and squid eyes

• Dragonfly wings and bird wings

• Bat wings and human arms

• Cow legs and whale flippers

Many different species share similar stages of early embryo development

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This suggests that species share a common ancestor. For example, all vertebrate embryos have a tail at some point.​

Similarities in embryo development

​Embryo Similarities cont

Also, many organisms share structures during embryo development

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For example, gill slits can be seen in human,

and chicken embryos. THese gills develop into other parts of our bodies but their presence suggests our ancestors had gills​

Multiple Choice

Guess the embryo

• fish

• snake

• snail

• human

Multiple Choice

Guess the embryo

• dog

• chicken

• mouse

• human

Multiple Choice

Guess the embryo

• eel

• snake

• worm

• human

Multiple Choice

Guess the embryo

• lizard

• chicken

• tortoise

• human

Multiple Choice

Guess the embryo

• turtle

• rabbit

• rat

• human

Multiple Choice

Guess the embryo

• chicken

• turkey

• eagle

• pigeon

Multiple Select

How do embryos provide evidence of common ancestry? Choose all that apply

• Many embryos have gill slits. This suggests they all evolved from the same ancestor

• The early stages of embryo development are similar in many different organisms. This suggests they all evolved from the same ancestor

• All embryos have eyes, so they all must have evolved from the same ancestor

• DNA in embryos is all the same, so all the parent organisms must have evolved from the same ancestor