Unit 2: Evolution Part B Lesson Topic Learning Goals 1 Lab Mechanisms of Evolution Cumulative Selection - Be able to describe evolutionary mechanisms such as genetic variations and key factors that lead to evoution - Be able to provide support for Darwin s unanswered questions - Identify the different types of selection that affect a species as it evolves - Distinguish between evolution as the result of ecology vs biology - Describe the process of speciation and pre vs post zygotic selectors - - Be able to apply some evolutionary mechanisms to a case study scenario. Activity Becoming Human - Analyze data to identify key factors in the evolution of man Lab Human Skull Comparison 2 Human Evolution - use appropriate terminology related to evolution while comparing the skulls of various Hominids. - You will demonstrate an understanding of the differences between hominid fossils - You will be able to explain the some differences in characteristics of primates - You will understand how to construct a cladogram or phylogenetic tree. - You will be able to explain the some differences in characteristics of HOMINIDS.
Lesson 1: Mechanisms for Evolution Types of Evolution As knowledge expands, particularly in the field of genetics we know have the most convincing evidence relating to the mechanisms of natural selection. Genetic Variation Geneticists of organisms. GENETIC DIVERSITY: Any trait, which Traits are coded for on in units called. Genes are located at specific (Positions on a chromosome) Most eukaryotes are (2 sets of homologous chromosomes) ALLELES: All individuals of the same species share a common (Complete set of chromosomes) However, each will have a different (Combination of alleles at specific loci). Differences in genotype and environmental influences account for different (observable traits)
Mutations result from Mutations are changes in the genetic code of genes Can have mutations. Only Variation within a species = of alleles possessed by individuals Population Genetic Diversity = enormously Sexual Reproduction = in each offspring Key Factors when Leading to Evolution 1. When populations are small, in allele frequencies. 2. When, individuals that are on more alleles 3. or changed, causing a change in allele frequency 4. Migration will remove alleles from one population and add them to another. 5. Natural selection causes certain alleles to be passed on increasing the relative frequency of alleles in the next generation. Types of Selection Many factors influence how selection can operate on individual phenotypes in a population 1. Stabilizing selection occurs when the within a population are by the environment. 2. Directional selection occurs when the individuals with more of a trait.
3. Disruptive selection favours individuals with variations at of a trait over individuals with intermediate variations. 4. Sexual selection favours the selection of any trait that of the individual. 5. Cumulative selection - Remember natural selection is not a matter of chance. Furthermore, it is a that selectively systems piece by piece, often just modifying previous systems to perform new functions. Evolutionary Change Without Selection Sometimes changes in genetic makeup of populations are not the result of traits of individuals. 1. Genetic Drift - Very important in small populations
a. BottleNeck Effect i. results in a in numbers ii. very small sample of alleles survives to establish a new population. b. Founder Effect i. Genetic drift that results when a 2. Gene Flow - Speciation Species - group of organisms that Species can be differentiated on a biological basis by identifying
Any series of events that results in the reproductive isolation of two populations may also lead to the formation of new species. Types of Speciation
Human Evolution Activity: Skull Comparison For each skull: Write the name of the organism Record the approximate age of the fossil Record information about the following: - sagittal crest, nuchal crest, facial prognethism, canine diastema, chin, nasal bones, brow ridge, incisor angle, and foramen magnum Determine if the skull is more ape- like or human- like Lesson 2: Human Evolution Human evolution began approx. with the earliest Three notable traits that appeared in primates were: o o o Over the next 20-30 million years these mammals o Prosimian - lemurs, pottos, and tarsiers are the most primitive of the primates - sometimes they are referred to as "pre- monkeys". There name means. Prosimians have: o A well developed sense of smell, and a more prominent snout. o Partial binocular vision (using two eyes together, as apes and monkeys do). Often nocturnal vision. o Have at least one claw and developed manual dexterity. o Immobilized upper lips. o A different dental formula - 2:1:3:3 o Prosimians only live in the 'Old World'. (area that don't include North and South America): Lemurs live only on the island of Madagascar, Tarsiers live on the islands of the Philippines, Borneo, Celebes Islands, and Sumatra, and Lorises live in areas of Africa and South/Southeast Asia Anthropoid - the anthropoid a number of times to give rise to the Old World monkeys and New World monkeys and the hominoids. (family Cercopithecinae). They are monkeys. They are, and are physically different as well. Old world monkeys have: Narrow and downward pointing nostrils. Longer hind legs than forearms.
Flattened nails on fingers and toes. Prominent buttock pads that they can sit on. Tails, but not prehensile (adapted for grasping or holding) ones. They are generally larger than the New World monkeys. : live in the neotropical forests of the "new world".new World - some are quite tiny, like the 6 inch pygmy marmoset, and some are larger - the howler monkey can be up to 3 feet in length. New World Monkeys are called platyrrhines. Characteristics of New World Monkeys: Wide nostrils which are circular and spaced apart. They are small to medium sized. Long tails which are sometimes prehensile. No buttock pads. No cheek pouches Hominoids - orangutans, chimpanzees, gorillas, humans and bonobos (shown below in order). These great apes are included under the family Hominidae - Gibbons o Like the great apes, they lack tails, and have the same dental formula. Their skulls are also similar to those of great apes, having enlarged braincases and huge eye orbits that face forward. Siamangs are the largest type of gibbon. Monkeys vs Apes Monkeys Apes
Emergence of Humans fossil record shows that the (humans and extinct members who arose from the most recent common ancestor that humans share with apes.) has a rich history of The oldest known biped 5.2-5.8 million years old Australopithecine footprints date to 3.7 million years. Our ancestors were There were at least 6 different species of australopithecines in Africa between 4.2 and 10 million years ago 3 million years ago australopithecine ancestor gives rise to 2 lineages. One of which goes on to form the genus Homo is an extinct hominid that lived between 3.9 and 2.9 million years ago. It is thought that A. afarensis was whether as a direct ancestor or a close relative of an unknown ancestor, than any other known primate from the same time
Oldest fossils of Homo are 2.4-1.6 million years ago. Generally classified as Homo habilis. Homo habilis gave rise to Homo erectus who is known for their H. erectus shows many human features. Approximately 2 million years ago H. erectus spread out from Africa to Europe and Asia. Within the last 600 000 years H. erectus may have H. heidelbergensis, H. neanderthalensis and H. sapiens. By 130 000 years ago when H. neanderthalensis was already living in parts of Europe and Asia. H. neanderthalensis were skilled tool makers, they performed burial ceremonies and may have been capable of complex speech.