SBI 3UMs.Zafar

Introduction to Evolution

Life is united and has descended from organisms that appeared early in Earth’s history

Fossils: preserved remains or markings left by organisms

Brief Introduction

The Polar Bear.One of the world’s newest mammalsTransparent fur helps with blending in Compare Arctic animals to Desert animals how have

each adapted to their respective environment?Around the world there is an enormous diversity of

life, and each species has its own set of characteristics what is a species?

For example …

Recall, a theory is a set of statements that explains a group of facts or phenomena

Charles Darwin developed a theory to explain the diversity of life and how all organisms are related to one another AND to the environments in which they live Darwin’s theory explained evolution

Evolution is a theory …

Evolution the idea that all species are descendents of ancient species that were different from modern-day species

The biological history of Earth

What is Evolution?

1) Species were fixed permanent2) That Earth was less than 10,000 years old

Before Darwin, it was believed that …

James Hutton Scottish Geologist. Proposed that rock formations are continually being formed. Studied present-day erosion and the thickness of sedimentary rock and what did he conclude?

Charles Lyell Popularized and expanded upon Hutton’s ideas in the 183os. Found more evidence to support the idea that rock formations were formed by very slow processes

Changing Ideas About the Natural World

Georges Cuvier French naturalist. Compared elephant bones with mammoth fossils. Concluded that mammoths were very different and a different species

Changing Ideas About the Natural World

Species are not permanent. They adapt to their environment. Three ideas:1. By using or not using certain body parts, an organism develops

certain characteristics. Ex: giraffes2. These enhanced characteristics would be passed on to the offspring -

Inheritance of acquired characteristics3. All organisms have a tendency towards perfection

*We now know that Lamarck’s hypotheses do not stand true. Because of our knowledge of DNA

Jean Baptiste Lamarck

1831 HMS Beagle set out to study the South American coastline

Darwin Naturalist. Collected lots of samples and maintained journals

Observed 3 patterns:1. Species vary globally2. Species vary locally3. Species vary over time

Darwin’s Observations

Distantly related animals living in different places but similar habitats looked similar and acted similar!

Species Vary Globally

Related animal species that occupied different habitats within a local environment had different features

Most obvious on the Galapagos IslandsEx: tortoises and rainfall levels-Isabela Island more rainfall tortoises get to vegetation

close to land-Espanola Island Dry and barren tortoises have longer

necks and notches in shells to allow them to reach high for food

Species Vary Locally

Species living today were descended from ancestral species

Example: Armadillo and Glyptodon

Species Vary Over Time