BIOL 152 1st Edition Lecture 8 Outline of Last Lecture Mendelian Genetics Outline of Current Lecture Speciation Current Lecture Phylogeny Anagenesis overtime one species changes to a different type of species Cladogenesis presence of one species that diverge into two different species Biological species concept populations or group of populations whose members have the potential to interbreed and produce viable offspring Reproductive Isolation are biological factors that impede members of two species from producing viable fertile offspring Prezygotic prevent mating or fertilization Habitat isolation Temporal isolation Behavioral isolation Mechanical isolation Gametic isolation Postzygotic prevent viable fertile hybrids Reduced hybrid viability can reproduce some hybrids These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Reduced hybrid fertility can t reproduce hybrids Hybrid breakdown can t reproduce after many generations Limitations of the Biological Species Concept Cannot be usefully applied to all species Fossils Asexual organisms Not enough is known about organism Additional definitions for species Morphological species concept are characterized by body shape size and structure Ecological species concept are characterized by species niche interactions with living and nonliving environment Phylogenetic species concept are characterized by their phylogeny on the animal lineage and genetics Speciation Allopatric speciation gene flow is reduced by physical barrier Population separated in space Allopatric speciation is much more common in animals Gene flow prevents allopatric speciation Secondary contact takes place and only then will it lead to hybridization Sympatric speciation gene flow is reduced by reproductive barrier Populations in same place but separated through small barriers More common in plants Polyploidy can lead to speciation Autopolyploidly having an extra set of chromosomes when reproduced from the same species Allolpolyploidy when hybrids develop gametes that reproduce to make new species Hybridization concept of species being separated by geographic barriers and their way of coming back together to reproduce viable offspring Reinforcement occurs when the hybrid offspring are selected against and the barrier between the species strengthens Fusion occurs when the two species come together and reproduce many viable hybrid offspring but leads to loss of divergent individuals Geographic or other biological barriers are weakened Stability occurs when both species survive and can also reproduce to make viable hybrid offspring Sympatric females living in the same geographic region chose males that look like them Allopatric females living in different geographic regions chose males of different species but look similar to the species of the female Tempo of speciation Gradualism uniformitarianism Punctuated equilibrium rapid speciation instantaneously in generation Adaptive radiation Is the rapid evolution of many diverse species from a common ancestor upon introduction to new environmental opportunities Cambrian Explosion lead to adaptive radiation Scale of Evolution Microevolution how gene frequencies change in a population Macroevolution the cumulative effects of speciation over vast amounts of time is evolutionary change above the species level Macro evolutionary Changes In most cases complex structures evolved in increments from much simpler versions that performed the same basic function this is known as exaptation such as Feathers Complex eyes Avian wings Homeotic genes determines where plant and animal appendages develop Homeotic genes are the masters in regulating gene development Encode specific Transcription Factors that control the expression of genes responsible for anatomical structures o Hox genes Heterochrony an evolutionary change in the rate or timing of development Allometry science of studying the differential growth rates of the parts of a living organism Paedomorphosis timing of reproductive development relative to somatic organs such that the sexually mature stage retains juvenile body features o Salamanders