Download 17-4 Patterns of Evolution

17-4 PATTERNS OF EVOLUTION

I. Extinction

1.

Macroevolution large-scale evolutionary patterns & processes that occur over long periods of time.

2.

Six important topics in macroevolution are: a) b) c) d) e)

f)

extinction adaptive radiation convergent evolution coevolution punctuated equilibrium changes in developmental genes

3.

4.

Over 99% of all species that have ever lived are now extinct Mass extinctions have: a)

b)

provided ecological opportunities for organisms that survived resulted in bursts of evolution that produced many new species

II. Adaptive radiation

1.

Adaptive radiation the process of a single species or a small group of species evolves into several different forms that live in different ways.

Adaptive Radiation of Mammals Artiodactyls

CetaceansPerissodactyls TubulidentatesHyracoids Sirenians Proboscideans

Ancestral Mammals Copyright Pearson Prentice Hall

2.

The evolution mammals is an example of adaptive radiation b/c many species of mammals evolved from one ancestral species

III. Convergent evolution

1.

Convergent Evolutionprocess whereby organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. a)

Ex: the similar nature of the flight/wings of insects, birds, pterosaurs (flying reptiles that are now extinct), and bats.

IV. coevolution

1.

2.

Coevolution- A process that takes place with two species evolve in response to each other as time passes. Ex: Predator/prey and parasite/host

Some Central American Acacia species have hollow thorns and pores at the bases of their leaves that secrete nectar (see image at right). These hollow thorns are the exclusive nest-site of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant—they also defend their acacia plant against herbivores. berkeley.edu

v. Punctuated equlibrium

1.

Gradualismevolutionary change is slow and steady

Copyright Pearson Prentice Hall

2. Punctuated equilibrium- a pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change.

Copyright Pearson Prentice Hall

vi. Developmental genes & body plans

1.

2.

3.

Scientist believe changes in genes for growth and differentiation during embryological development could produce changes in body shape and size. Small changes in the activity of control genes can affect many other genes to produce large changes in adult animals. Small changes in the timing of cell differentiation and gene expression can make the difference between long legs and short ones. Copyright Pearson Prentice Hall

Evolution of Wings in Insects

Ancient Insect

Two Types of Modern Insects

Copyright Pearson Prentice Hall