Speciation: the origin of species How many species? Number described: 1.5 – 1.6 million Number estimated: 5-6 million to 100 million. Species: smallest.

Slides:



Advertisements
Similar presentations
Chapter 24 The Origin of Species TOP 5.
Advertisements

Evidence of Evolution Fossil record Homologous structures Comparative Geological Distribution of organisms Homologous structures Comparative embryology.
THE ORIGIN OF SPECIES CHAPTER 24.
Evolution of Populations The Modern Synthesis Population genetics integrates Darwinian evolution and Mendelian Genetics Important terms in population.
Species Concepts Species Concept: An idea of what kind of entity is represented by the word SPECIES. There are several concepts recognizing the special.
Sympatric Speciation Flies (Rhagoletis pomonella) (1) Larvae develop in hawthorns (Crataegus) Native to NE U.S. (2) Larvae develop in apples (Pyrus) Apples.
Population Change n Speciation is the outcome of isolation and divergence. Isolation is created by reductions in gene flow. Divergence is created when.
Warm-up- 5 minutes Explain the biological species concept.
Speciation = the origin of species Factors that have accelerated speciation: In plants: use of different animal pollinators In animals: modifications in.
The formation of new species.. In evolutionary terms a species is a group of populations whose members have the potential to interbreed in nature and.
How do species occur? Concept 24.2: Speciation can take place with or without geographic separation Speciation can occur in two ways: – Allopatric speciation.
Chapter 24 The Origin of Species.
Species and Their Formation
Species and Their Formation
Species and Mechanisms of Speciation
Chapter 24 The Origin of Species. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Speciation = origin of new species.
True or False 1. Speciation can be observed only over millions of years. 2. Some features (such as the human eye) are too complex to evolve by natural.
Natural selection The process by which traits become more or less common in a population through differential survival and reproduction.
Copyright © 2009 Pearson Education, Inc. PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey.
The Origin of Species Speciation. Speciation is the process by which one species splits into two or more species Speciation explains the features shared.
Species and Mechanisms of Speciation. I. Species Definitions Species represent the boundary for the spread of alleles and define the unit in which the.
Outstanding Origin of Species Ch 24. Vocabulary  1. Macroevolution – origin of new taxonomic groups (new species, genera, families etc)  2. Speciation.
Chapter 24: The Origin of Species Macroevolution Macroevolution Cumulative effects of speciation over vast amounts of time Cumulative effects of speciation.
Copyright © 2009 Pearson Education, Inc. PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey.
Chapter 14 The Origin of Species Lecture by Joan Sharp.
CHAPTER 24 THE ORIGIN OF SPECIES 1.
Chapter 24. Microevolution: change in allele frequencies in a population over time Macroevolution: broad pattern of evolution above the species level.
The Origin of Species.  Two basic patterns of evolutionary change can be distinguished –Anagenesis –Cladogenesis.
Chapt.: 21- The Species Concept “Species and Their Formation” How does one species arise from another? Is a new species always better adapted to.
Mechanisms of Evolution. Macroevolution Speciation.
Biology 3201 Chapters The Essentials. Micro vs. Macro Evolution Micro Evolution Evolution on a smaller scale. This is evolution within a particular.
The Origin of Species Presented & supported two hypotheses:
Chapter 24 Origin of Species.
Process of Speciation. –In the 150 years since the publication of Darwin’s book On the Origin of Species by Means of Natural Selection, new discoveries.
Objective: Speciation Do Now: Why is this population of horses considered to be the same species?
Mader: Biology 8 th Ed.. Population Genetics Genetic diversity in populations changes over generations Forces that cause populations to evolve Allele.
Chapter 24: Speciation Objectives -Importance of reproductive isolation in the biological species concept -Speciation can take place with or without geographic.
THE ORIGIN OF SPECIES Chapter 24.
What is a Species? Biological species = A population or group of populations whose members have the potential to interbreed with one another in nature.
The Origin of Species Chapter 24 Bozeman Tutorial: SpeciationBozeman Tutorial: Speciation (11:39)
1. 2 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Sylvia S. Mader Immagini e concetti della biologia.
Macroevolution and the Definition of Species. Overview: That “Mystery of Mysteries” In the Galápagos Islands Darwin discovered plants and animals found.
Speciation. Learning objective SWBAT: Describe and identify the various types of reproductive isolation necessary for the formation of new species according.
Chapter 24 The Origin of Species. Speciation – The process whereby members of one species become another species – A species can evolve through time without.
The Origin of Species What is a Species? Modes of Speciation Origin of Evolutionary Novelty.
1.C.2 Reproductive Isolation Speciation may occur when two populations become reproductively isolated from each other.
Objective: Speciation Do Now: Why is this population of horses considered to be the same species?
Evolution of Populations
Chapter 24 The origin of Species

1.
The Origin of Species Chapter 22.
Speciation Speciation -the central process in evol.
SPECIATION UNIT 5 EVOLUTION.
Speciation Chapter 14 March 2014.
The Origin of Species Chapter 24.
NAME: DATE: PERIOD: Speciation Plant Sciences, 2001Updated: June 1, 2012 Gale Document Number: GALE|CV Outline key terms Speciation is the process.
Evolution and Zygotic Barriers (Part 5)
Chapter 24 The Origin of Species.
Chapter 24 The Origin of Species.
Chapter 24: The Origin of Species
Chapter 24 The Origin of Species
Video worksheet – due tomorrow
Chapter 22 Bozeman Tutorial: Speciation (11:39)
The Origin of Species Chapter 24.
Outstanding Origin of Species
Evolution Glencoe Chapter 15.
Chapter 11 Evolution of Populations
Chapter 24 The Origin of Species
Presentation transcript:

Speciation: the origin of species How many species? Number described: 1.5 – 1.6 million Number estimated: 5-6 million to 100 million. Species: smallest evolutionarily independent unit (fundamental unit of biodiversity). Species boundaries –geographical –genetic –How do species originate? –Speciation mechanisms

Autoploidy Alloploidy Species of tobacco Speciation mechanisms 1. Increasing number of sets of chromosomes A. Alloploidy: stage in the speciation process B. Autoploidy: doubling of homologous chromosomes results in fertility Hybridization very common in plants

1. Uncommon in a nimals Increasing sets of chromosomes Hybridization Very rarely produces a new species Species 1 (unparental) Species 2 (biparental) New species 3

Attempts to recreate an animals species. Laboratory Hybridization Among North American Whiptail Lizards, Including Aspidoscelis inornata arizonae X A. tigris marmorata Squamata: Teiidae), Ancestors of Unisexual Clones in Nature CHARLES J. COLE, LAURENCE M. HARDY, HERBERT C. DESSAUER, HARRY L. TAYLOR, AND CAROL R. TOWNSEND Division of Vertebrate Zoology (Herpetology), American Museum of Natural History Division of Vertebrate Zoology (Herpetology), American Museum of Natural History; Museum of Life Sciences, Louisiana State University in Shreveport, LA Division of Vertebrate Zoology (Herpetology), American Museum of Natural History; Department of Biochemistry and Molecular Biology, Louisiana State University Health Science Center, New Orleans, LA Division of Vertebrate Zoology (Herpetology), American Museum of Natural History; Department of Biology, Regis University, Denver, CO Division of Vertebrate Zoology (Herpetology), American Museum of Natural History

Attempt to create a parthenogenetic species in the lab. Attempt spanned a period of > 29 years 74 males of four species caged with 156 females of nine species Each group kept together for at least six months. A total of only five hybrids from three crosses were obtained over the 29 years. Hybrids were raised to adulthood to see if they would reproduce, but none did. The hybrid status of suspected laboratory hybrids was confirmed by karyotypic, allozyme, and morphological analyses, and histological studies were made on reproductive tissues of the hybrids, which were apparently sterile. Three laboratory hybrids of two bisexual species, A. inornata arizonae (♀) x A. tigris marmorata (♂)…..progenitor species of A. neomexicana. These three individuals from one clutch of eggs were the only hybrids between two bisexual species that we obtained.

Bisexual parents used in attempt to recreate the origin of Aspidoscelis neomexicana

Hybrid intersex Hybrid male The attempted recreation, A. neomexicana

Speciation Mechanisms Most animal speciation is visualized as lineage splitting. Y Darwinian idea: slow accumulation of genetic differences. Another idea: big changes can occur rapidly from small changes in developmental pathways. Basic speciation models require separation of gene pools. 1. Dispersal: either setting up peripheral isolates or island hopping. 2. Vicariance: population is subdivided by extraneous geological or climatic events. 3. Habitat segregation typically messy

Speciation by Vicariance Asynchronous closure (3 mya) Snapping shrimp species DNA sequence divergence Morphological differences Reproductive isolation

How many species of African elephants? Sample: 195 elephants from 21 populations Four genes sequenced – genetic distances used to construct a phylogeny Conservation implications Two species (using a phylogenetic species concept) Speciation by habitat isolation

Speciation by Dispersal Representative Hawaiian Drosophila diversity

Aspidoscelis carmenensis A. picta A. danheimae A. franciscensis A. espiritensis Speciation by dispersal

Speciation nearing completion? northwest Arizona Aspidoscelis tigris

Sample 4 in the middle of a step cline. Phenotypically intermediate. Why? center

Assortative mating?