Chapter 15 Origins of Biological Diversity What is

Chapter 15 Origins of Biological Diversity

What is a Species? • Species – Distinct form of life – Creates much diversity or variety within life • Biological Species concept – defines species as a population or group of populations whose members have the ability to reproduce

Micro and Macro Evolution • Microevolution – changes or mutations within the genes of a population • Macroevolution – major biological changes evident in the fossil record – Ex. Extinction of a species, new features like wings

Reproductive Barriers Between Species • Reproductive Isolation – condition in which a reproductive barrier keeps two species from interbreeding – Timing – Different breeding seasons – Behavior – Different courtship or mating behaviors – Habitat – Adapted to different habitats in the same general location – Physical differences – reproductive structures are physically incompatible – Fertility – unable to reproduce

Geographic Isolation and Speciation • Geographic Isolation – separation of populations as a result of geographic change or migration to geographically isolated places – Ex. Mountain forms, glacier movement • This can lead to new evolutionary developments and then new species • Speciation – formation of a new species

Geographic Isolation and Speciation

Adaptive Radiation • Adaptive Radiation – evolution from a common ancestor of many species adapted to diverse habitats – Ex. Hawaiian Islands • Some species go through a modification process in which existing adaptations are refined as well as adaptation of existing structures to new functions – Ex: Exoskeleton of arthropods years ago – protection – Today – protection and prevents water loss

Adaptive Radiation

Embryology • Embryology – study of the processes of multicellular organisms as they develop from fertilized eggs to fully formed organisms • The developmental timing of organisms can cause variation • Ex. Salamanders that live in trees have shorter toes and more webbing than those that live on the ground; the growth of the feet of the tree dwellers ends sooner than those that live on land

Fossils • Fossils – preserved remains or markings left by an organism that lived in the past – Footprints, eggs, bones, etc • Fossil Record – Chronological collection of life’s remains in sedimentary rock layers – Supplies much information about macroevolution

Geologic Time Scale • Geologic Time Scale – four distinct ages of earth’s history – Eras • Precambrian, Paleozoic, Mesozoic, and Cenozoic – Periods • Ex: Jurassic – Dinosaurs

Dating Fossils • Radiometric Dating – based on the measurement of certain radioactive isotopes in objects • Half-life – the number of years it takes for 50% of the original sample to decay

Continental Drift • Continental Drift – motion of continents about Earth’s surface on plates of crust floating on the hot mantel – Paleozoic Era – all land masses together created “Pangea” with huge environmental changes – Mesozoic and Cenozoic Eras – land masses begin to drift apart • Species must now adapt and huge macroevolution changes occurred

Mass Extinction • Mass Extinction – episode of great loss of species – Ex: Dinosaurs • Leads to adaptive radiation of surviving species

Modern Taxonomy • Taxonomy – branch of biology that deals with identifying, classifying, and naming species • Classification – organizing species into larger groups of related species

• Modern Taxonomy Carolus Linnaeus – Binomial Nomenclature – two part naming system • Genus and species name • Ex: Domesticated dogs Genus: Canis Species: familiaris Wolves Genus: Canis Species: lupus

7 Levels of Classification • • 1. kingdom 2. phylum 3. class 4. order 5. family 6. genus 7. species – When moving down this list, organisms in each classification level are more closely related

The Three Domains of Life • Domain – Broadest category of classification – Archaea, Bacteria, Eukarya • Kingdoms – category of classification after domains – 4 kingdoms within Eukarya domain • Animals, Plants, Fungi, Protists – 1 kingdom within Archaea domain • Archaebacteria – 1 kingdom within the Bacteria domain • Eubacteria

The Idea of Evolution • Charles Darwin – Studied the similarities and differences between organisms at the Galápagos Islands • He became convinced that organisms change over time • Evolution – The development of new types of organisms from preexisting types of organisms • Natural Selection - The process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do