Chapter 22 Mechanisms of Evolution

Carolus Linnaeus interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose Linnaeus was the founder of taxonomy, the branch of biology concerned with classifying organisms[K.P.C.O.F.G.S] He developed the binomial format for naming species called binomial nomenclature(for example, Homo sapiens)

Binomial Nomenclature Uses a two-part naming system for organisms; the two names are Latin scientific names The name consist of the genus and the species of the organism Example: Panthero leo which is the scientific name for lion This system was developed in the 18 th Century by Carolus Linnaeus

Hierarchical Classification Linnaeus introduced a system for grouping species in increasingly inclusive categories The taxonomic groups from broad to narrow are domain, kingdom, phylum, class, order, family, genus, and species A taxonomic unit at any level of hierarchy is called a taxon The broader taxa are not comparable between lineages – For example, an order of snails has less genetic diversity than an order of mammals

Figure 26.3 Cell division error Species: Panthera pardus Genus: Panthera Family: Felidae Order: Carnivora Class: Mammalia Phylum: Chordata Domain: Archaea Kingdom: Animalia Domain: Eukarya Domain: Bacteria

Paleontology, the study of fossils, was largely developed by French scientist Georges Cuvier Cuvier advocated the principle that events in the past occurred suddenly, like catastrophes, and by different mechanisms than those occurring today He believes that’s what explains boundaries between strata and location of different species

Geologists James Hutton and Charles Lyell perceived that changes in Earth’s surface can result from slow continuous actions still operating today, and at the same rate This view strongly influenced Darwin’s thinking

Lamarck’s Hypothesis of Evolution Lamarck hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics[workbook page 156] Darwin [page ]

Concept 22.3: Evolution is supported by an overwhelming amount of scientific evidence New discoveries continue to fill the gaps identified by Darwin in The Origin of Species There are four types of data that document the pattern of evolution[pages ] – 1.Direct observations – 2.Homology – 3.The fossil record – 4.Biogeography

1.Direct Observations of Evolutionary Change Two examples provide evidence for natural selection: 1.Insect populations can rapidly become resistant to pesticides 2.evolution of drug-resistant viruses and antibiotic-resistant bacteria

2.Homology  Homology is similarity resulting from common ancestry Scientist use different types of comparative studies to show that certain organisms have a common ancestor

Types of Comparative studies: Comparative Anatomy  The scientist compare skeletal structures of different vertebrates to see if they have a similar basic structure The different types of structures are: 12

 Homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor – Similar in structure; made up of the same type of bones – But have different functions

Figure HumanCatWhaleBat Humerus Radius Ulna Carpals Metacarpals Phalanges

 Vestigial structures are remnants of features that served important functions in the organism’s ancestors

 Comparative embryology reveals anatomical homologies not visible in adult organisms – For example, all vertebrate embryos have a post- anal tail and pharyngeal arches

Figure Chick embryo (LM) Pharyngeal arches Post-anal tail Human embryo

 Molecular Homologies: shared characteristics on the molecular level Example: Comparing the amino acid sequence code in species to show similarities thus indicating common ancestor

19

20

 Convergent evolution is the evolution of similar, or analogous, features in distantly related groups It explains why distantly related species can resemble one another Convergent evolution has taken place when 2 organisms developed similarities as they adapted to similar environmental challenges; not because they evolved from a common ancestor

3.The Fossil Record The fossil record provides evidence of the extinction of species, the origin of new groups, and changes within groups over time Fossils can document important transitions

4.Biogeography Biogeography, the scientific study of the geographic distribution of species, provides evidence of evolution Earth’s continents were formerly united in a single large continent called Pangaea, but have since separated by continental drift An understanding of continent movement and modern distribution of species allows us to predict when and where different groups evolved

Endemic species are species that are not found anywhere else in the world Islands have many endemic species that are often closely related to species on the nearest mainland or island Darwin explained that species from the mainland colonized islands and gave rise to new species as they adapted to new environments

Chapter 26: The evolutionary history of life

Phylogeny is the evolutionary history of a species or group of related species – For example, a phylogeny shows that legless lizards and snakes evolved from different lineages of legged lizards The discipline of systematics classifies organisms and determines their evolutionary relationships[ go to page 180]

27

Figure 26.2 ANCESTRAL LIZARD (with limbs) Geckos No limbs Snakes Iguanas Monitor lizard Eastern glass lizard No limbs

Figure 26.4 Order Family GenusSpecies Panthera pardus (leopard) Taxidea taxus (American badger) Lutra lutra (European otter) Canis latrans (coyote) Canis lupus (gray wolf) Panthera Taxidea Lutra Felidae Mustelidae Carnivora Canis Canidae 2 1

What We Can and Cannot Learn from Phylogenetic Trees Phylogenetic trees show patterns of descent, not phenotypic similarity Phylogenetic trees do not indicate when species evolved or how much change occurred in a lineage It should not be assumed that a taxon evolved from the taxon next to it

Applying Phylogenies Phylogeny provides important information about similar characteristics in closely related species A phylogeny was used to identify the species of whale from which “whale meat” originated

Figure Lancelet (outgroup) Lamprey Bass Frog Turtle Leopard Hair Amnion (b)Phylogenetic tree Four walking legs Hinged jaws Vertebral column Leopard TurtleFrog BassLampreyLancelet (outgroup) TAXA Vertebral column (backbone) Hinged jaws Four walking legs Amnion Hair CHARACTERS (a)Character table