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Tom Horvath Department of Biology SUNY College at Oneonta
Not Necessarily on Purpose: Domestication and Speciation in the Canidae Family Tom Horvath Department of Biology SUNY College at Oneonta
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Who is Whoâs Best Friend?
The dog is said to be a manâs (humanâs) best friend, but it could also be said that we are a dogâs best friend. Objectives: How to interpret phylogenetic diagrams. Understand how natural selection can work on a population to cause speciation. Distinguish between natural and artificial selection.
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Dog Breeds The winner of Best of Show at the 2009 Westminster Dog Show was a Sussex Spaniel. âStumpâ the spaniel competed against 170 other breeds of domestic dog (an intraspecies competition). Where do so many breeds come from? How did the species we recognize as the domestic dog arise? Image credit-- Description: Stump is named Best in Show at the Westminster Kennel Club Dog Show. Source: also available at Modifications: Cropped. Author: Kjunstorm (Lori) Licensing: This image is licensed under the Creative Commons Attribution ShareAlike 3.0 License.
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The start of our story⊠A young boy is sitting near the edge of a cave 20,000 years ago. He has just taken out the garbage from the groupâs previous dayâs activities. The garbage consists of mostly bones and scraps of food from a recent successful hunt. As dusk approaches, the wolves start to arrive. The boy is not frightened. He has seen the wolves many times before. In fact, their arrival is almost ritualistic. They move in from the forest and wait until all the humans have gone into the cave for the night. The boy notices that the same wolf is the first one to get to the good scraps. It doesnât immediately run off when it sees the boy. Domestic dogs wouldnât appear on the scene for another 5,000 yearsâŠ.
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a boy looked out of a cave âŠ
20,000 years ago, a boy looked out of a cave ⊠Image creditsâ Description: Cave, National Park OjcĂłw, Poland. Source: Author: Jan JerszyĆski (2005) Licensing: This image is licensed under the Creative Commons Attribution ShareAlike 2.5 License. Description: Wolf pack (Canis lupus) in animal park of Gramat in France. Source: Author: Julien 31 Licensing: This image is licensed under the Creative Commons Attribution ShareAlike 3.0 License.
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The Family Canidae Image creditâ
Source: Anatomical engraving from Handbuch der Anatomie der Tiere fĂŒr KĂŒnstler, Wilhelm Ellenberger and Hermann Baum, and medical illustrator, Hermann Dittrich and 1911 through Scan from See also University of Wisconsin Digital Collections at Licensing: This is a faithful photographic reproduction of an original two-dimensional work of art. The work of art itself is in the public domain its copyright has expired. This applies to the United States, Australia, the European Union and those countries with a copyright term of life of the author plus 70 years.
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Members of the Family Canidae
Jackal (Black-backed jackal) Fox (Kit fox, Red fox) Wolf (Gray wolf) African wild dog Members of the Family Canidae Image creditsâ Slide 7 âTop, and Slide 16 âBottom right Description: Black-backed Jackal in the Masaai Mara, Kenya, April 2008 Source: Author: Simyre Licensing: This image has been released into the public domain by its author Slide 7 âRow 2, left Description: San Joaquin Kit Fox Source: U.S. Fish and Wildlife Service, National Digital Library, Author: B. Peterson Licensing: Public domain. Slide 7 âRow 2 right, and Slide 16 âTop right Description: Red Fox Source: U.S. Fish and Wildlife Service, National Digital Library, Author: Ronald Laubenstein Slide 7 âRow 3, and Slide 16 âBottom left Description: Gray Wolf, taken in the Garden for Zoologic Research, Tel Aviv University, Israel Source: Author: Yonidebest, Hebrew Wikipedia Licensing: The copyright holder of this file, Yonidebest, allows anyone to use it for any purpose, provided that the copyright holder is properly attributed. Slide 7 âBottom Description: African Wild Dog (Lycaon pictus) Source: Author: Philip Gabrielsen Licensing: This image is licensed under the Creative Commons Attribution 2.5 License.
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Domestic dogs look like they are more closely related to wolves than other canids.
Gray wolf Siberian husky (domestic dog) Image creditsâ Slide 8 âLeft, and Slide 9 âLeft Description: Gray wolf, Canis lupus Source: U.S. Fish and Wildlife Service, National Digital Library, Author: Gary Kramer Licensing: Public domain. Slide 8 âRight, Slide 16 âTop left, Description: Siberian Husky Source: Author: Hinrich Licensing: This image is licensed under Creative Commons Attribution ShareAlike 2.0 Germany License. Slide 8 âLower center Description: Coyote Source: Author: Macmanes Licensing: This image is licensed under the Creative Commons Attribution ShareAlike 3.0 License. Coyote
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Of course, looks can be deceiving!
Gray wolf Domestic dog (Lhasa apso) Image credits-- Slide 9 âRight Description: Lhasa Apso femea com 6 meses Source: Author: Lcfrederico Licensing: Permission is granted to copy, distribute and/or modify this image under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. Phylogenetic analyses are more convincing.
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Phylogenetic Analysis
Phylogenies can be based on morphology Similarity of many morphological characteristics are used (color, size, structure, etc.) Most recent phylogenies are based on molecular similarities E.g., similarities of mitochondrial DNA (mtDNA) sequences More similarities (i.e., fewer dissimilarities) = a closer relationship
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The study of evolutionary relationships
Phylogeny The study of evolutionary relationships Think of it as a family tree A B C D Recent time Past Remember that this is just a hypothesis of common ancestry. This is rooted. Species A, B, C & D all exist in modern times
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The study of evolutionary relationships
Phylogeny The study of evolutionary relationships Think of it as a family tree Sp A Sp B Sp C Sp D Unique ancestor of D only Common ancestor=nodes. Blue is a lineage. Common ancestor of both C & D, but not A & B Common ancestor of A, B, C & D
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CQ#1: Which statement can be made about this phylogeny?
Species A, B, and C are extinct. Species C & D shared a common ancestor more recently than B & D. Species D will display the most advanced morphological characteristics. Species D is most closely related to Species A. Species D evolved from Species C. Sp A Sp B Sp C Sp D
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Cladograms are another way to look at phylogenies
Image creditâ Slide 14 and Slide 29 âLeft Description: Domestic dog phylogeny Source: Figure 1 from: Jordana J., Manteca X., Ribo O. Comparative analysis of morphological and behavioral characters in the domestic dog and their importance in the reconstruction of phylogenetic relationships in canids. Genet. Mol. Biol. [serial on the Internet] Mar [cited 2009 July 24] ; 22(1): 49â57. Available from: doi: /S Permission: According to articles may be reproduced without specific permission from Genet. Mol. Biol. for use on a non-profit basis in teaching.
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Species A Species B Species C Species D Species E Species F
Introduce clades here. Clades share a derived characteristic. Also called synapomorphies. Species A and B are sister taxa Species A & B are more similar to each other than they are to any other species Species A-D are more similar to each other than they are to either species E or F Species C & D shared a common ancestor in more recent times than the shared common ancestor of A-D
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In Groups: Discuss relationships and create a cladogram for:
Fox Domestic dog Image credit-- Wolf Jackal
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CQ#2: Which of the following most closely resembles your cladogram?
Wolf Jackal Fox Dog Wolf Jackal Fox A. C. D. Dog Wolf Jackal Fox Dog Wolf Jackal Fox E. Wow, mine looks like none of these
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Canid Phylogeny Slide 18 âCenter, Slide 19 âRight
Description: Canid phylogeny Source: Permission: According to âImages may be downloaded and reproduced for non-profit personal or educational purposes without further permission.â
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CQ#3: According to the molecular evidence shown in the cladogram, which statement is most true?
Foxes and wolves are closely related. Domestic dogs and wolves are as closely related to each other as they are to coyotes. Out of the canids tested, a Gray wolf is the most likely ancestor of the domestic dog. The domestic dog is the most evolved of the canids.
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Comparing wolves with dogs
Morphological comparisons (examples) Dogs tend to have curled tails, wolves have straight tails. Dogs tend to have smooth short coats. Skull shape differs. Molecular comparisons Gray wolves and dogs differ by no more than 0.2% in their mtDNA sequence. In contrast, gray wolves and coyotes differ by at least 4%.
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How did dogs evolve from wolves?
Competing hypotheses Ancestral wolf pups were domesticated intentionally by early humans â Artificial selection. Ancestral wolf populations experienced natural selection forces that favored dog-like characteristics.
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Hypotheses 1 â Artificial Selection
Arguments for It makes intuitive sense that ancestral wolves could be domesticated easily since they are so dog-like. Early humans would have intentionally bred ancestral wolves. Arguments against Why would any human want to deal with an animal that avoids humans? Modern wolves can not be âdomesticatedâ by training alone. It takes intensive and sophisticated selective breeding.
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Hypothesis 2 â Natural Selection
Canids are very resourceful & would have found human waste piles good foraging â wolves were living close to humans. Wolves are shy, skittish animals â only âadventurousâ wolves would have stayed close to the waste piles while humans were around. The âadventurousâ wolves were the best fed and hence had high fitness. This hypothesis is based on Coppinger, Raymond and Lorna Coppinger Dogs: A New Understanding of Canine Origin, Behavior and Evolution. ISBN: (ISBN-10: ) Fall 2002
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CQ#4: What is fitness in the evolutionary sense?
Being the strongest and most able to get food. Being able to survive and reproduce more successfully than others. Being the most aggressive and fending off potential predators. Being the smartest and remembering where the best food resources are.
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CQ#5: What characteristic is being selected for in the ancestral wolf population under Hypothesis 2?
Ability to interact with humans. Capability of eating human waste. Behaviors that lead to tolerance of humans being around. Inability to run away from humans.
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A Plausible Series of Events
Those ancestral wolves that tended to tolerate humans would have had the best access to high-quality food (scraps). Canids likely would have protected their scrap piles from other invading animals and possibly even strange humans.
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What did humans give dogs?
Easy access to high-quality food. A safe âhomeâ to raise pups. What else⊠The bullets could be left out and allow students to group and come up with a list of advantages that humans provided for dogs (or ancestral wolves). Image creditâ Slide 27 Description: Two dogs on sofa Source: Thomas Horvath, Department of Biology, SUNY College at Oneonta Permission: Used with permisssion.
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CQ#6: What did the first "dogs" give humans that is the most significant in evolutionary terms?
An efficient garbage disposal. An affectionate pet. An early warning system that someone or something was approaching. This could be an optional slide Alternative is to ask students to re-group and come up with evolutionary advantages that humans received by their association with dogs.
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Phylogeny of Domestic Dog Breeds â Result of Artificial Selection
Image creditsâ Slide 29 âTop left Description: Afghan Hound Source: Author: Sannse Permission: Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. Slide 29 âTop right Description: Irish Setter Source: Author: Luis Miguel Bugallo SĂĄnchez Slide 29 âFarthest left Description: Akita-Inu Source: Author: Slide 29 âMiddle Description: Alaskan Malamute Source: Author: PardoY Slide 29 âFarthest right Description: Siberian Husky Source: Author: Utopialand Slide 29 âLower left Description: Samoyed Source: Slide 29 âLower right Description: Chow-chow Source: Author: Jurriaan Schulman
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Evidence for Evolution
Paleontology â fossils show change in a species over time Biogeography â Similar species are found in similar ecosystems around the world Morphology â Comparing structures Homologous structures â body parts with similar structure but possible different function. Shows common ancestry Analogous structures â similar structure develops in organisms that share a common ecosystem but not a common ancestry Biochemical or Molecular - Similarities in gene sequences, proteins, DNA
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Fossil record Sedimentary rock are richest source of fossils
fossil record is a substantial, but incomplete, chronicle of evolutionary history incomplete historical documents of biology history of life on Earth is punctuated by mass extinctions 5000 year old ice mummy found on an Alpine ridge dividing Austria from Italy at 10,500 feet above sea level.
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Relative Dating
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Evolutionary Time Scale
Microevolution â changing of allele frequencies in a population over time. Macroevolution â patterns of change over geologic time. Determines phylogeny Gradualism â species are always slowly evolving Punctuated equilibrium â periods of massive evolution followed by periods with little to no evolution
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Homologous Structures
Anatomical evidence Anatomical evidence 1. These structures are called⊠homologous 2. These structures are evidence forâŠ. common ancestry 3. similar internal structure = similar development 4. different function = different environment & niche 5. close evolutionary râship!
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Analogous structures Solving a similar problem with a similar solution
Convergent evolution Donât be fooled by their looks! same function different development & anatomy Those fins & tails & sleek bodies are analogous structures! convergent evolution - NOT common ancestor Those fins & tails & sleek bodies are analogous structures! Does this mean they have a recent common ancestor? Solving a similar problem with a similar solution
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Evaluating molecular homologies
Aligning DNA sequences more bases in common = more closely related analyzed by software beware of molecular homologies
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Comparative hemoglobin structure
Molecular Homology The sequence in DNA & proteins is a molecular record of evolutionary relationships. Why compare DNA & proteins across species? 10 20 30 40 50 60 70 80 90 100 110 120 Lamprey Frog Bird Dog Macaque Human 32 8 45 67 125 Comparative hemoglobin structure Molecular Record What are we comparing here? -ï comparing DNA (base sequence) & proteins (amino acid sequence) What assumption do we make about genes and relatedness? ï the more closely related, the more DNA bases & amino acids you have in common have to compare genes for protein the organisms have in common⊠canât compare genes for proteins you donât have Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans
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Phylogeny & Systematics
evolutionary history of a species based on common ancestries inferred from fossil record morphological & biochemical resemblances molecular evidence Systematics connects classification system to phylogeny by categorizing & naming organisms
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Systematics Connecting classification to phylogeny hierarchical system
Carolus Linnaeas latin binomial genus species
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Illustrating phylogeny
Cladograms patterns of shared characteristics Classify organisms according to the order in time at which branches arise along a phylogenetic tree
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Molecular Systematics
Hypothesizing phylogenies using molecular data apply principle of parsimony simplest explanation fewest evolutionary events that explain data hypothetical bird species 3 possible phylogenies (there are more)
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Parsimony Choose the âtreeâ that explains the data invoking the fewest number of evolutionary events
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Parsimony & analogy vs. homology
Phylogenetic trees are hypotheses Which is the most parsimonious tree?
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Modern Systematics Shaking up some trees!
Crocodiles are now thought to be closer to birds than other reptiles
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TAXA Lancelet (outgroup) (outgroup) Lancelet Lamprey Leopard Bass Frog
Figure 20.11 TAXA Lancelet (outgroup) (outgroup) Lancelet Lamprey Leopard Bass Frog Turtle Lamprey Vertebral column (backbone) 1 1 1 1 1 Bass Vertebral column Hinged jaws 1 1 1 1 Frog Four walking legs Hinged jaws CHARACTERS 1 1 1 Turtle Four walking legs Amnion 1 1 Figure Constructing a phylogenetic tree Amnion Hair 1 Leopard Hair (a) Character table (b) Phylogenetic tree 46
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Three Big Ideas about Phylogenetic Trees
Time runs from the root to the tips of the tree, not across its tips The branching pattern of a tree indicates relatednessâtaxa that share more recent common ancestors are more closely related. Trees depict evolutionary relationships, not evolutionary progress. Try #8 on page 398.
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