3 3 15 Chapter 14 Macroevolution Know terms Cenozoic Mesozoic dinosaurs flourished Paleozoic What is a species Countless small 1700s Carolus Linnaeus defined species by appearance Also he created a naming scheme Biological Species Concept BSC defines species based on their potential to interbreed and produce fertile offspring Naturally occurring populations Allows organisms to decide Lots of expectations in unnatural situations Cases of hybridization are interesting but does not negate this EXAMPLE LION AND TIGER Definition doesn t apply to all concept LIKE Fossils Bacteria Asexual organisms Other ideas of species concepts Plato s idea typological concept Morphological species concept Phylogenetic species concept Dogs Coyotes Wolves each separate species Hybrids are possible Wolf dog hybrids Dangerous Coyote wolf hybrids Interbreeding natural populations Speciation Formation of new species Clicker Biological species concept cannot be applied to extinct organisms Reproductive Isolation new species potential to interbreed defines species Reproductive Isolation Prezygotic isolation Keep egg and sperm from ever meeting Right after fertilized egg Prexygotic reproductive barriers prevent fertilization FIGURE 14 3 Temporal Isolation skunk species that mate at different times Behavioral Isolation wolf spiders Gametic Isolation sea urchins whose gametes cannot fuse Habitat Isolation Garden snakes Postzygotic zygote form cant develop normally or able to reproduce Reproductive barriers reduce fitness of offspring produced by members Horse and Donkey MULE hybrid Hybrid What is a zygote Spatial Geographic Patterns define 2 types of speciation Allopatric Speciation barrier physically separates a population into 2 groups that cannot interbreed No contact come back cant interbreed EX desert mountain MAYR Squirrels in Grand Canyon Sympatric Speciation Continuous contact between populations Chichlid fish have diversified into several species Polyploid individuals offspring with more chromosomes than either parent Pace of Speciation fossil record supports Gradualism Darwinism Punctuated equilibrium Stephen J Gould