Patterns of Evolution Types of Evolution Speciation illustrates

Types of Evolution… Speciation illustrates how new species might arise from a common ancestor…

Notes Divergent evolution… occurs when a number of species develop from one common ancestor,

Notes Divergent Evolution has resulted in a phenomenon known as Adaptive Radiation Adaptive radiation

These mammals are all thought to have evolved from a shrew-like ancestor. This

Australian marsupials show adaptive radiation Due to action of different selection pressures, different characteristics

Notes Convergent evolution… occurs when groups of organisms which are not closely related, but

Convergent evolution… when unrelated species develop the same characteristics and so come to resemble

Convergent evolution… Anteaters show features that were selected for because they gave them an

Over to you… 1. Convergent Evolution Worksheet 2. Refer to p 130 Science Quest

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Patterns of Evolution

Types of Evolution… Speciation illustrates how new species might arise from a common ancestor… BUT Does it account for the variety of life forms that exist …………… now …………… before us?

Types of Evolution…

Notes Divergent evolution… occurs when a number of species develop from one common ancestor, becoming less and less alike over time. Structures that result from common ancestry, but do not necessarily perform the same function are known as homologous structures. E. g forearm of mammals (human v bats)

Divergent evolution…

Notes Divergent Evolution has resulted in a phenomenon known as Adaptive Radiation Adaptive radiation is where the divergent evolution of one species has resulted in the formation of many species that are adapted to a variety of environments. Can you think of some examples?

These mammals are all thought to have evolved from a shrew-like ancestor. This is an example of adaptive radiation

Australian marsupials show adaptive radiation Due to action of different selection pressures, different characteristics have been selected

Notes Convergent evolution… occurs when groups of organisms which are not closely related, but occupy similar habitats, come to resemble each other. These organisms can look similar but have very different genes. Structures that evolve to perform similar functions, but do not have the same basic structure (ie. have not evolved through ancestry) are called analogous structures.

Convergent evolution… when unrelated species develop the same characteristics and so come to resemble each other.

Convergent evolution…

Convergent evolution… Anteaters show features that were selected for because they gave them an advantage in obtaining food within their environment, but not because of common ancestry Australian marsupials and placental mammals of other continents have many similarities, but are not closely related

Over to you… 1. Convergent Evolution Worksheet 2. Refer to p 130 Science Quest 10 Complete questions 4 – 8, 11, 13