AP Biology Macroevolution Part 2

Modes of Speciation Allopatric speciation Sympatric speciation

Geographic Range of west coast salamanders (A ring species)

Galapagos Islands

Galapagos Islands close up

Darwin’s Galapagos Island finches

Modes of Speciation Allopatric speciation Sympatric speciation

Failure of cell division in a cell of a growing Autopolyploidy Failure of cell division in a cell of a growing diploid plant after chromosome duplication gives rise to a tetraploid branch or other tissue. Offspring with tetraploid karyo- types may be viable and fertile—a new biological species. Gametes produced by flowers on this tetraploid branch are diploid. 2n 2n = 6 4n = 12 4n

Allopolyploidy Unreduced gamete with 4 chromosomes Unreduced gamete Hybrid with 7 chromosomes Viable fertile hybrid (allopolyploid) Meiotic error; chromosome number not reduced from 2n to n Species A 2n = 4 2n = 10 Normal gamete n = 3 Normal gamete n = 3 Species B 2n = 6

Stephen Jay Gould

. Time Gradualism model Punctuated equilibrium model

Mass extinctions over time Millions of years ago 600 500 400 300 200 100 100 2,500 Number of taxonomic families 80 2,000 Permian mass extinction ) Extinction rate 60 1,500 Number of families ( Extinction rate ( 40 1,000 Cretaceous mass extinction ) 20 500 Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Proterozoic eon Neogene Ceno- zoic Paleozoic Mesozoic

Snowball Earth

Pangaea By about 10 million years ago, Earth’s youngest major mountain range, the Himalayas, formed as a result of India’s collision with Eurasia during the Cenozoic. The continents continue to drift today. Cenozoic North America Eurasia By the end of the Mesozoic, Laurasia and Gondwana separated into the present-day continents. 65.5 Africa South America India Madagascar Australia Antarctica Laurasia By the mid-Mesozoic Pangaea split into northern (Laurasia) and southern (Gondwana) landmasses. 135 Gondwana Millions of years ago Mesozoic At the end of the Paleozoic, all of Earth’s landmasses were joined in the supercontinent Pangaea. 251 Pangaea Paleozoic

Asteroid Impact NORTH AMERICA Chicxulub crater Yucatán Peninsula

Example of Descent with Modification and Natural Selection

Evolution of the eye Pigmented cells (photoreceptors) Pigmented cells Epithelium Nerve fibers Nerve fibers Patch of pigmented cells Eyecup Fluid-filled cavity Cellular fluid (lens) Cornea Epithelium Optic nerve Pigmented layer (retina) Optic nerve Pinhole camera-type eye Eye with primitive lens Cornea Lens Retina Optic nerve Complex camera-type eye