Evolution

Adaptation What do these bugs have in common? A flower mantid in Malaysia A leaf mantid in Costa Rica

Darwin’s Voyage Studied theology At age 22, 5yr, voyage on the Beagle Similarities between living and fossil organisms Figure 13.1A

Figure 13.4

Galapagos Islands Isabela Darwin Wolf Pinta Marchena Genovesa Fernandia Santiago Bartolomé Rabida Pinzon Seymour Baltra Santa Cruz Santa Fe Tortuga Española San Cristobal Floreana

Figure 13.5

Aristotle Judeo-Christian culture Lamarck –Inheritance of acquired traits Early Ideas

Geology Geologists proposed… –Very old Earth –Changed by gradual processes

Darwin and Wallace 1859 On the Origin of Species Natural Selection –The mechanism of evolution –Artificial selection? Descent with Modification

Figure 13.2A Hundreds to thousands of years of breeding (artificial selection) Ancestral dog (wolf) Figure 13.2B Artificial Selection

Living species… …Are descended from earlier forms Thousands to millions of years of natural selection Ancestral canine African wild dogCoyote Wolf Fox Jackal Figure 13.2C Natural Selection

Fossils A Skull of Homo erectus D Dinosaur tracks C Ammonite castsB Petrified tree E Fossilized organic matter of a leaf G “Ice Man” F Insect in amber Evidence for Evolution

Figure 13.7

The fossil record –Time lines Figure 13.3H Evidence for Evolution

Fossils link extinct species w/ living species Figure 13.3I Evidence for Evolution

Biogeography –Geographic distribution of species –Why are marsupials found mostly in Australia? Evidence for Evolution

Figure 13.10

Comparative anatomy –Homologous structures similar characteristics from common ancestry Evidence for Evolution Human CatWhale Bat Figure 13.4A

Comparative Embryology Evidence for Evolution Post-anal tail Pharyngeal pouches Chick embryo Human embryo Figure 13.4B

Molecular Biology –Comparing DNA between different organisms Table 13.4 Evidence for Evolution

Natural Selection Darwin’s observations –Overproduction –Individual variation –Differential reproductive success Who will survive and reproduce?

Natural selection –Certain traits increase survival –Those indiv. influence the future Where can we observe changes in traits? Natural Selection

Figure 13.14

What is a population? Population genetics Population Evolve

Populations Evolve Gene pool –All genes in a population Sources of genetic variation –Mutations –Meiosis –Fertilization

Populations Evolve Individuals don’t evolve! Evolution is change in frequency of traits in a population!

Or not? What would a nonevolving population look like? Stable allele frequency Populations Evolve

–Genes are shuffled during sexual reproduction –does not alter the proportions of alleles –P 2 + 2pq + q 2 = 1 Phenotypes GenotypesWWWw ww Number of animals (total  500) Genotype frequencies    0.04 Number of alleles in gene pool (total  1,000) Allele frequencies 800 1,000  0.8 W  0.2 w 640 W 160 W  160 w 40 w Figure 13.7B 200 1,000 Hardy-Weinberg Equilibrium

Genetic Equilibrium No mutation Large population Isolation Everyone reproduces Random mating

Microevolution Drives a population away from equilibrium: Natural selection and… –Gene flow –Genetic drift –Mutations

Genetic Drift Random fluctuation of allele frequencies overtime More pronounced in small populations

Figure 13.22

Computer Simulation AA in five populations allele A lost from four populations Generation (25 stoneflies at the start of each)

Computer Simulation allele A neither lost nor fixed Generation (500 stoneflies at the start of each)

Bottleneck Effect A severe reduction in population size Lots of drift Example –Elephant seals 20 individuals –rebounded to 30,000

Bottleneck Original population Bottlenecking event Surviving population Figure 13.9A Figure 13.9B

Figure 13.24

Inbreeding Leads to increased homozygosity Can lower fitness More recessive alleles are expressed Amish, cheetahs

Founder Effect A few individuals start a new population Allele frequencies of founders may be different from original population

Figure 13.25

Gene Flow Genes move in/out of a population Immigration/emigration Minimizes genetic variation between populations

Mutations Infrequent –Lethal –Neutral –Advantageous

Natural Selection Revisited Largest impact Successful alleles = successful phenotypes Who will reproduce? What will happen to allele frequencies? Increased fitness!

Natural Selection Revisited Directional Selection Number of individuals in the population Range of values for the trait at time 1 Range of values for the trait at time 2 Range of values for the trait at time 3 Number of individuals in the population Number of individuals in the population

Antibiotic Resistance Since 1940s Overuse Resistant forms

Natural Selection Revisited Stabilizing Selection Number of individuals in the population Range of values for the trait at time 1 Range of values for the trait at time 2 Range of values for the trait at time 3

Natural Selection Revisited Disruptive Selection Number of individuals in the population Range of values for the trait at time 1 Range of values for the trait at time 2 Range of values for the trait at time 3 Number of individuals in the population Number of individuals in the population

Sexual Selection

Question of the Day Antibiotic resistant bacteria are showing up all over the place. The infamous “flesh eating” bacteria is an example. What are two things that you can do to help prevent more bacteria from becoming antibiotic resistant?