Biological Diversity Macroevolution: Ch. 15

Review What is microevolution? Evolution on the smallest scale –Generation to generation change in the frequencies of alleles w/in a population –Divirsification of a species Different types of dogs Microevolution and adaptation explain HOW populations evolve What if this was the ONLY type of evolution that happened? Earth would be inhabited only by a highly adapted version of the 1st form of life!

Objectives 1.Microevolution vs. macroevolution 2.Reproductive barriers between species 3.Explain how geographic isolation and adaptive radiation contribute to species diversity 4.Evolution refines existing adaptations

Species How can you determine whether a group of plants or animals belong to the same species? Is appearance a sufficient criterion?

Are these dogs in the same species?

What about these vegetables? What is the species for veggies? Dogs? –Brassica oleracea –Canis familiaris

Eastern and Western Spotted Skunks Same species? Even though they look very similar, they are different species…

Clarification of the Term Species Species: –Members of a population who breed and produce fertile offspring Wolverine: Gulo gulo The diversity of life is based on the origin of new species…

Origin of Life Before we get into macroevolution, let’s look at one view of the origin of life on earth.

Macroevolution Macroevolution: –Major biological changes over millions of years –Origin and extinction of different species –Evolution of new features (i.e., wings) How does this happen?

What can separate different populations of a single species? Geographic isolation: –Separation of species as a result of geographical change Antelope squirrel and white-tailed antelope squirrel Can’t cross deep canyon or river

More on Geographical Isolation Adaptive radiation: –Evolution from a common ancestor that results in diverse species adapted to different environments

No Breeding Allowed! Reproductive Isolation: –Barrier that keeps species from interbreeding What are these barriers? Timing –Different breeding seasons Behavior –Different mating behaviors Habitat: –Feeding habitat, maintains isolation Other –Incompatible structures, infertile offspring (horse + donkey = infertile mule)

Carl Sagan’s view on evolution.

How long did this all take? Let’s put it into perspective. Timeline Tapping activity 4.6 billion years condensed into 12 months

A Remodeling Process Eyes have evolved into a camera-like structure! Activity 15.2

Adaptations of Existing Structures to New Functions Chitin –Forms exoskeleton of arthropods (insects, spiders, scorpions, lobsters) –In ocean, used for protection from predators –On land helps to resist water loss Chemical changes made it more water-tight

Fossils:Evidence for Macroevolution rich storehouse of information about macroevolution Organized into geological time scale

The Burgess Shale

Continental Drift: More Evidence Continents separated What did this allow? Organisms evolved in different environments

Bonus Video: KT Asteroid and Dinosaurs

More Bonus Video: Creating Life