Ch. 15 Evolution p

15.1 Darwin’s Theory of Natural Selection p. 418 – 422

Main Idea Charles Darwin developed a theory of evolution based on natural selection.

What was the primary mission of the Beagle? To survey the coast of South America

What did Darwin make collections of? Rocks, fossils, plants and animals

What did Darwin notice as he made collections of the animals in the Galapagos Islands? He noticed that the different islands seemed to have their own, slightly different varieties of animals

What are two examples of when artifical selection occurs? When breeding dogs When new strains of crops

What was interesting about almost every specimen that Darwin collected in the Galapagos? It was new to European scientists

What did Darwin hypothesize? New species could appear gradually through small changes in ancestrial species

What did Darwin reason from the economist Malthus’ ideas? That some competitors in the struggle for existence would be better equipped for survival than others Those less equipped would die

What are the four basic principles of Darwin’s theory? 1. Individuals in a population show differences, or variances 2. Variations can be inherited 3. Organisms have more offspring than can survive on available resources 4. Variations that increase reproductive success will have a greater chance of being passed on

Visualizing Natural Selection: give an example of how a sunflower population exhibits the for principles of natural selection Variation – some sunflowers are taller than others Heritability – tall sunflowers produce tall sunflowers; short sunflowers produce short sunflowers Overproduction – each sunflower has hundreds of seeds, most of them will not germinate Reproductive advantage – shorter sunflowers reproduce more successfully

Evolution Cumulative changes in groups of organisms through time

How does the term evolution relate to natural selection? Natural selection is a means of explaining how evolution works

15.2 Evidence of Evolution p

Main Idea Multiple lines of evidence support the theory of evolution

What did On the Origin of Species demonstrate? How natural selection might operate

What also did it provide? Evidence that evolution has occurred on our planet

What does a theory explain? How some aspect of the natural world operates

What does the theory of evolution state? It states that all organisms on Earth have descended from a common ancestor.

What do fossils provide? A record of species that lived long ago

Why is the fossil record important? It is an important source of information for determining the ancestry of organism and the patterns of evolution.

What is a transitional fossil? A fossil that contain features shared by different species

Derived trait Newly evolved features, such as feathers, that do not appear in the fossils of common ancestors

Ancestral trait More primitive features, such as teeth and tails, that do appear in ancestral forms

Homologous structures Anatomically similar structures inherited from a common ancestor

Give an example of homologous structures Bird wings and reptile limbs They are similar shape and construction, indicating that they were inherited from a common ancestor

Vestigial structures Structures that are reduced forms of functional structures in other organisms

Give an example of vestigial structures: Snake pelvis – attachment point for legs and is non functional in animal without legs Kiwi wings – too small to be of any use in flight Human appendix – important in many mammals, but of limited use in humans and some apes

Embryo An early, pre-birth stage of an organism’s development

Biogeography Study of the distribution of plants and animals around the world

What are the 5 topics that offer evidence for evolution: 1.Fossil record 2.Comparative anatomy 3.Comparative embryology 4.Comparative biochemistry 5.Geographical distribution

What is an adaptation? A trait shaped by natural selection that increases an organism’s reproductive success.

Fitness A measure of the relative contribution an individual trait makes to the next generation.

The better an organism is adapted to its environment, the greater its chances of survival and reproductive success.

Camouflauge Morphological (form & structure) adaptations that allow them to blend in with their environments

Mimicry A morphological adaptation where one species evolves to resemble another species