ANT 301 Notes: Primate Diversity and Evolution PDF

1.13 Diversity: What is a Primate? ➔​(not bold = don’t need to write ➔​(bold = write) ➔​Anthropology: the study of humans ◆​Greek anthropos: human ◆​Greek -logos: science of (literally “word) ➔​Biological anthropology is the study of the behavior, ecology, & evolution of p...

1.13 Diversity: What is a Primate? ➔​(not bold = don’t need to write ➔​(bold = write) ➔​Anthropology: the study of humans ◆​Greek anthropos: human ◆​Greek -logos: science of (literally “word) ➔​Biological anthropology is the study of the behavior, ecology, & evolution of primates, including humans. ◆​It is: 1.​Empirically-based 2.​Grounded in the scientific method 3.​Synthetic Syllabus Overview: ➔​You are required to download and print out lab materials and bring them to class in order to receive credit for lab ➔​BUT you will submit your completed lab exercises on Canvas ➔​Slides are not posted ➔​No Final Exam ➔​* indicates list 1.15 What is a Primate? ➔​Order Primates: ◆​Lemurs, lorises, monkeys, apes, humans. ➔​Carolus Linnaeus ◆​Formalized naming system ◆​In the book “Systema Naturae” ◆​Created in 1758 ➔​Linnaean Taxonomic Hierarchy ◆​Kingdom: Animalia ◆​Phylum: Chordata ◆​Class: Mammalia ◆​Order: Primates ◆​Family: Hominidae ◆​Genus: Homo ​ (must be underlined or in italics to be correct) ◆​Species: sapiens ​ (genus name capitalized, not species name. Will get wrong if species is capitalized) ➔​Linnaeus also included bats as closely related to humans ◆​Order Chiroptera ➔​“Flying Lemur” or Colugo as closely related to humans ◆​Order Dermoptera ➔​Tree Shrews ◆​Order Scandentia ➔​Primates may be recognized by a set of shared characteristics ◆​Non-Primates, don’t got em (bats, colugo, tree shrews) ◆​Primates, got em ➔​Primate Characteristics (not all have but most do):  1.​Forward-Facing Eyes* a.​Owl monkey b.​Bushbaby 2.​Wide Binocular Field and Stereoscopy* a.​Stereoscopy ~ sense of 3-dimensionality that comes with mental fusion of the slightly different images from right and left eyes. i.​ Test/Demo: Floating Hot Dog b.​Binocular Vision and Stereoscopy critical for fine depth perception i.​ Test/Demo: Pencil Trick 3.​High Visual Acuity* 4.​Orbit Surrounded by Bone* 5.​More/ Larger Visual Brain Areas* 6.​Grasping (Prehensile) Hands/ Divergent Thumb* 7.​Grasping (Prehensile) Feet/ Divergent Big Toe* 8.​Flattened Nails instead of Claws* 9.​Large Apical Pads of Tops of Digits 10.​ Small Litter Size* a.​Usually 1 11.​ Slow Life History* a.​Long i.​ Gestation ii.​ Infant dependency iii.​ Juvenile period iv.​ Lifespan ◆​Traits #’s 1-11 found in most living primates because they were present in the last common ancestor (LCA) of primates. ◆​These features NOT present in the LCA of mammals. ​ LCA of mammal traits: ○​ Clawed ○​ Nafs and feet not prehensile ○​ Relatively poor vision, narrow binocular field ○​ Large litters/ short period of infant dependency ➔​Why did the characteristic features of primates evolve?  ◆​Arboreal Hypothesis: (first explanation) ​ Sir Graftion Elliot-Smith (Australian Anatomist) ​ Primates evolved from an arboreal ancestor - unique traits are adaptations to life in trees ​ What is wrong with Arboreal Hypothesis? ○​ Problem #1: not all arboreal mammals have forward-facing eyes.* ◆​Ex. Squirrel ~ arboreal mammal, but not a primate/ non-primate characteristic. ○​ Problem #2: not all arboreal mammals have grasping hands and feet with nails instead of claws.* ◆​Ex. Sloth, Bears, Kinkajou. ○​ Conclusion: arboreality in itself is insufficient to account for the evolution of typical primate characteristics. ○​ COMPARATIVE METHOD is important! ◆​Like astronomy, political science, etc. ➔​So who does have forward facing eyes? A.​Nocturnal Visual Predators* 1.​Commonalities of Prey Capture Style? a.​Many predators capture their prey by mouth. b.​Predatory primates, cats, and owls all capture prey with an appendage c.​Binocular vision important for depth perception to guide strike... judging distance between eyes, target, and appendage is functionally analogous d.​Earliest fossil primates were small nocturnal predators ➔​So who does have grasping hands and feet? A.​Small arboreal mammals that inhabit a “fine branch niche”* ◆​Visual Predation Hypothesis (second explanation) ​ Matt Cartmill (American Biological Anthropologist)  ​ Last common ancestor of primates was small, arboreal, nocturnal, a visual predator, and occupied a microhabitat characterized by small-diameter supports. ​ Largely replaced the arboreal hypothesis 1.22 Primate Diversity Primate Taxonomy ➔​Textbook Handout ◆​“-oidea” = superfamily ◆​“-idae” = family ◆​“-inae” = subfamily ➔​Taxonomy: the science of naming and classifying organisms ◆​The specific scheme of classification started with Linnaeus ◆​Two Taxonomies for Primates: ​ Ecologically-Based (Older Version) ○​ Prosimii ◆​Lemurs ◆​Lorises ◆​TARSIERS ○​ Antropoidea ◆​Monkeys ◆​Apes ◆​Humans ​ Phylogenetically-Based (Newer Version) ○​ Phylogeny: hypothesis of an organism’s evolutionary relationships ○​ Strepsirrhini ◆​Lemurs ◆​Lorises ○​ Haplorhini ◆​TARSIERS ◆​Monkeys ◆​Apes ◆​Humans  ​ Ecology: study of an organism’s interaction with its environment ◆​Tarsiers ​ Tarsiers are found only in Asia ​ They are 100% faunivorous ○​ they only eat small vertebrates ○​ as opposed to fruit ​ Tarsiers have huge eyes because they are nocturnal ​ Tarsiers share some derived (apomorphic) features with anthropoids; this is one of those traits ○​ 1. Reduced size and complexity of their nasal cavity ○​ 2. Loss of rhinarium ◆​Strepsirrhines ​ Strepsirrhines are found only in Africa, Asia, and Madagascar ​ Strepsirrhines share some derived (apomorphic) characteristics as well ○​ 1. Sloping talofibular facet ○​ 2. Reduced upper incisors ○​ 3. Grooming Claw ○​ 4. Toothcomb ​ Order: Primates ○​ Suborder: Strepsirrhini ◆​Infraorder: Lemuriformes ​ Lemurs ○​ Lemurs are found only in madagascar ​ Family: Indriidae ○​ Indri ◆​Females are larger than the males ◆​These are the largest living lemurs 1.27 Primate Diversity Introduction to the Order Primates ➔​Sifaka ◆​Vertical clinging and leapers ➔​Infraorder: Lemuriformes ◆​Family: Lemuridae ​ ringtail, ruffed (varecia), true lemurs (eulemur), bamboo lemurs ​ Females are at the center of the order ◆​Family: Lepilemuridae ​ sportive lemurs or lepilemur ​ all energy goes to digesting their food because they have little digestive space ◆​Family: Daubentonidae ​ Aye-ayes or Daubentonia madagascariensis ​ Truly solitary ​ have the largest brain to their body size ➔​Infraorder: Lorisiformes ◆​Lorisiformes are found in Africa and Asia ◆​Family: Galagidae ​ Bushbabies or galago ◆​Family: Lorisidae ​ Slow loris or lorises ○​ Only venomous primate ​ Slender loris ​ Potto ​ Angwantibo ➔​Derived Features of Anthropoids ◆​Anthropoids ​ Fused frontal ​ Fused mandibular symphysis  ​ Larger brain ​ Lacrimal bone in orbit ◆​Prosimians ​ Unfused frontal ​ Unfused symphysis ​ Lack of closure ◆​Strepsirrhine ​ Postorbital bar only ◆​Tarsier ​ Partial postorbital plate ◆​Anthropoid ​ Complete postorbital plate Semiorder: Haplorhini ➔​Suborder: Anthropoidea ◆​Infraorder: Platyrrhini ​ Monkeys in the Americas (New World Monkeys) ​ Zygomatic-parietal contact ​ Three premolars ​ No ear tube ​ Family: Pitheciidae ○​ Sakis, Titis, Uakaris ◆​Saki Monkeys ​ 1-4kg ​ Diet: seeds and fruit ◆​Uakaris ​ 2-4kg ​ Diet: seeds and fruit ◆​Titi Monkeys ​ 700-1200g ​ Diet: fruit, leaves, and insects ​ Family: Cebidae ○​ Marmosets, tamarins, squirrel monkeys, capuchin ◆​Pygmy Marmoset ​ 130g body mass ​ Diet:gums ◆​Marmosets ​ 200-350g body mass  ​ Diet: fruit, insects, gums ​ Females don’t take much care of the offspring because they are so large ○​ usually has twins ​ Both twins have some genes from the each of the males ◆​Tamarins ​ 450g body mass ​ Diet: fruit, nectar(dry season) ◆​Callitrichinae ​ Golden Lion Tamarin ​ Goeldi’s Monkey ◆​Owl Monkeys ​ Nocturnal ○​ Only nocturnal anthropoid ○​ 950g body mass ○​ Diet: fruit, leaves, insects ◆​Capuchin Monkeys ○​ Tool use ○​ Coalitions ○​ Concept of fairness ​ White-Throated Capuchin ○​ 2.7-3.9 kg body mass ○​ Diet: fruit, nuts ​ Brown Capuchin ○​ 1.3-4.8 kg body mass ○​ Diet: fruit, seeds ◆​Squirrel Monkeys ​ 550-1250g body mass ​ Diet: insects, other animal prey ​ Family: Atelidae ○​ Only group of primates that have a prehensile tail ○​ Spider monkeys, howlers ◆​Spider monkeys ​ White Bellied Spider Monkey ○​ 7-10 kg body mass  ○​ Diet: ripe fruit ​ Muriqui/ Wooly Spider Monkeys ○​ 10-12 kg body mass ○​ Diet: leaves, fruit ◆​Howler Monkeys ○​ 4-11 kg body mass ○​ Diet: leaves, fruit ​ Red Howler ​ Mantled Howler ◆​Woolly Monkeys ​ 5-9 kg body mass ​ Diet: fruit ​ Female dispersal ​ 2 kinds of males? ◆​Infraorder: Catarrhini (Superfamily:cercopithecoidea) ​ Monkeys in Asia and Africa; monkey, apes, humans ​ Frontal-sphenoid contact ​ Two premolars ​ Ear tube ​ Subfamily: Colobine ○​ High cusps on teeth ○​ Complex stomach ​ Subfamily: Cercopithecinae ○​ Low cusps on teeth ○​ Cheek pouches ◆​Guenons ​ Red-tailed Guenon ◆​Vervet Monkeys ◆​Patas Monkeys ​ 7-13 kg ◆​Baboons ​ Guinea Baboon ○​ 13-26 kg ​ Chacma Baboon ○​ 16-20 kg ​ Olive Baboon ○​ 14-28 kg ​ Hamadryas Baboon  ○​ 12-21 kg ◆​Geladas ​ Diet: grass ​ One male, multiple female groups ◆​Drills and Mandrills ​ Huge sexual dimorphism ​ Large groups ​ Large home ranges ​ Frugivores ​ Drills: 10-17 kg ​ Mandrills: 12-27 kg ◆​Macaques ​ Celebes ○​ 5-10 kg ​ Long-tailed ○​ 3-7 kg ​ Rhesus ○​ 5-8 kg ​ Japanese ○​ 8-11 kg ​ Bonnet ​ Lion-tailed ​ Tonkean ◆​Colobus Monkeys ​ Angolan Colobus ○​ 7-10 kg ​ Eastern Black and White Colobus ○​ 8-14 kg ​ Red Colobus ◆​Leaf Monkeys/ Langurs ​ Hanuman Langur ​ Thomas Langur ​ Capped Langur ​ Banded Leaf Monkey ​ Silvered Langur ​ Gee's Golden Langur ​ Javan Langur ​ Francois Langur  ◆​Colobines ​ Douc Langur ○​ 8-11 kg ​ Snub-nosed monkeys ○​ 20 kg ​ Proboscis Monkey ○​ 10-21 kg ​ Superfamily: Hominoidea ○​ Apes and humans ○​ Africa and asia ◆​Cercopithecoids ​ Bilophodont molars ◆​Hominoids ​ Larger brain ​ Simple molars ​ No tail ◆​Gibbons ​ Genus Hylobates ​ 5-6 kg ◆​Orangutans ​ Genus Pongo ​ 37-77 kg ​ “Great apes” ​ Diet: ripe fruit ◆​Gorillas ​ Diet: herbaceous vegetation ◆​Common Chimpanzees ◆​Bonobo ​ Pan paniscus ​ 31-39 kg ◆​Humans 2.3 Introduction to Evolution ➔​Evolution is the single most important concept in modern biology. ➔​Scientific Knowledge is: ◆​1. Empirical ​ Based on observations of the world around us (often quantitative) ◆​2. Testable ​ Often through experimentation ​ Potentially falsifiable ​ Repeatable ➔​Science can’t answer certain questions ➔​3-Part hierarchy of scientific certainty: ◆​Hypothesis ~ untested but consisted with prior known facts ◆​Theory ~ hypothesis supported by substantial empirical data - answers WHY ​ Complex with multiple parts ◆​Law ~ statement that predicts the results of certain initial conditions, so well-supported as to be considered fact - WHAT HAPPENS ​ Explanation of WHAT HAPPENS that it is so well-supported as to be considered fact - irreducible ➔​Scientific Theory ~ a well established explanation of some part of the natural world than can incorporate facts, laws, inferences, and tested hypotheses ◆​A scientific theory includes multiple parts ◆​No amount of validation changes a multi-part theory into a law ◆​ex. gravity, plate tectonics ➔​Evolution is a scientific theory that:  ◆​Incorporates multiple facts ◆​Predictions of the unifying theory have been repeatedly confirmed ◆​Universally accepted within the scientific community ➔​Evolution: change in allele frequencies in a population over time ◆​(Will have to write out this definition on EVERY LECTURE EXAM for every class you will ever take ​ Gene: small section of DNA that codes for a protein ​ Alleles: variants of the same gene ​ Population: unit of evolutionary change ○​ Individuals don't evolve ◆​Genetic material must change for evolution to occur ➔​Two Levels of Studying Evolution: ◆​1. Microevolution ​ Short time frame (months, years) ​ Genetic changes within a species ◆​2. Macroevolution ​ Long time frame (millions of years) ​ Origin and extinction of species ➔​A Brief History of Evolutionary Thought ◆​European thought during the Middle Ages: ​ 1. Earth at the center of universe ○​ Ptolemy ~ 140 A.D. ​ 2. Earth very young ◆​James Ussher ​ Earth created on Sunday Oct. 23, 4004 BC ◆​Plato ​ “World of Ideals” ​ Species based on a fixed “ideal type” ◆​Aristotle ​ “Scala Naturae” ○​ Organisms can be grouped on a linear scale from simple to complex  ○​ Humans on top; everything is striving to be human ​ Great Chain of Being ​ Classifying all living things ◆​Teleology ~ the use of ultimate purpose or ensign as a means of explaining natural phenomena ​ Think divine purpose ◆​Summary: ​ 1. World young and at center of universe ​ 2. Fixity of species ○​ No evolution ​ 3. Humans at top of Scala Naturae ​ 4. Organisms successful at what they do, because that's how they were designed ◆​Copernicus ​ Sun is the center of the universe ​ Hypothesis testing using empirical data ◆​Galileo ​ Showed copernicus was right ◆​Linnaeus ​ Binomial classification ○​ Founded modern taxonomy with Systema Naturae ​ Used common attributed to group organisms ​ Grouped HUMANS with other primates in animal kingdom ○​ Shifted us from linear thinking to tree thinking ◆​Owen ​ Homology ○​ Defined “the same organ in different animals under every variety of form and function” ◆​Buffon ​ Leclerc, Comte de Buffon ​ 1. The earth > 6000 y.o. ​ 2. Species change over time ​ 3. Notes anatomical similarity between humans and apes and discussed possibility of common ancestry ◆​Lamarck ​ 1st to propose a mechanism to explain HOW evolution might occur: ○​ Changed through striving ​ Acquired characteristics passed on to offspring ​ Mechanism was wrong ○​ Adaptation occurs over time in response to environmental change ◆​Cuvier ​ Established extinction as a fact ​ Explanation: Catastrophism ○​ Geological epochs end with sudden violent events (ex. great floods) leading to mass death ​ Provided further evidence that the earth is OLD ◆​Lyell ​ Uniformitarianism ~ same geological processes observable today also happened in past ​ Given enough time, small changes can have a large effect ◆​Malthus ​ Economist ​ Disease and other factors keep population in check ○​ If left unchecked, a population will tend to increase faster than available food resources ◆​Summary: ​ 1. World very old & not at center of universe (Copernicus, Galileo, Cuvier, Lyell) ​ 2. Humans are animals and have the same basic anatomical features as many other animals (Linneaus, Owens) ​ 3. Species can change over long periods of time in response to change in the environment (Buffon, Lamarck) ​ 4. Some species that were alive in the past no longer exist (Cuiver)  ​ 5. Incremental changes over long periods of time can have a BIG effect (Lyell) ​ 6. When resources are limited, there is competition for resources (Malthus) ◆​Darwin ​ Origin of Species (1859) ​ Correctly identified the MECHANISM by which biological evolution occurs ​ Observations ○​ 1. Much natural Variation ○​ 2. Struggle for Existence ​ 3 Fundamental Principles ○​ 1. Ability of population to explain is infinite, but carrying capacity of environment is finite ○​ 2. Individuals of a given species vary in morphology and behavior, and this variation leads to differential survival and reproduction ○​ 3. Some of this variation is transmitted from parents to offspring ◆​Traits that confer advantages in survival and reproduction are retained in population (selected for) ◆​Disadvantageous traits disappear over time (selected against) ​ Natural Selection ◆​Wallace ​ Independently came up with Natural Selection ◆​Mendel ​ Worked out the basics of genetics and inheritance ​ Used peas ​ Mendels Contributions ○​ Basic rules of heritability ○​ Genotype vs. Phenotype ○​ No blending inheritance; (variation is maintained in population from 1 generation to the next) ➔​Natural Selection and The Modern Synthesis ◆​Natural Selection* ○​ When these 3 conditions occur, evolutionary change is inevitable (100% probability) ​ 1. Variation ​ 2. Heredity ​ 3. Differential Reproduction ◆​Definitions: ​ Reproductive Success (RS) ~ # of offspring one produces that reaches reproductive age ​ Fitness ~ an individual's RS relative to the RS of other members of the same species ​ Adaptation ~ a trait that is favored by natural selection ➔​DNA ◆​DNA molecules are made up of nucleotides ◆​3,000,000,000 nucleotides in human DNA ◆​25,000 functional genes that code for proteins ​ 1% of total? ○​ 1% of your genome codes for proteins ○​ 4% regulates the 1% ○​ 45% repetitive “parasitic” DNA ◆​Doesn't do anything and just replicates like a virus ○​ 1% actual retroviruses ○​ The rest (about 49%) ◆​may not do much of anything ◆​Human genome compare with the common chimp genome ​ 97% identical in terms of genome ◆​Mutation ~ random process by which environmental factors or “errors” in cell duplication change an individual's genetic material ​ ex. Create new alleles; switch off genes; duplicate entire genes; etc. ​ Many types of mutagens ○​ Radiation ○​ Chemicals ○​ Viruses ◆​Most mutations are NEUTRAL ​ Disadvantageous (selected against) ​ Beneficial given the current state of the environment (selected for) ​ For evolution to occur, genes may be based on → mutation must occur in your gametes (eggs or sperm) ​ Important Points ○​ Nutation occurs in INDIVIDUALS ○​ Natural Selection occurs at the level of the INDIVIDUAL ○​ EVOLUTION occurs at the level of the POPULATION ◆​Individuals don't evolve, population evolve ​ Evolution ~ change in allele frequency in a population over time 2.10 Natural Selection and the Modern Synthesis ➔​Evolution ~ change in allele frequency in a population over time ➔​Forces of Evolution ◆​1. Natural Selection: occurs when there is variation in a population, traits are hereditary, and there is differential reproductive success in a population ◆​2. Mutation: mistake in the DNA sequence ​ Random and non-directional ​ Provides the variation for another mechanism to act upon ◆​3. Gene Flow: a change in gene frequencies in a population due to migration from or interbreeding with individuals from another population ​ Has to be the same species but you get this interbreeding between populations ◆​4. Genetic Drift: a random process where gene frequencies change by chance ➔​Natural Selection and the 4 Forces of Evolution + The Laws of Heritability + Understanding of Protein Synthesis = The Modern Synthesis ➔​Microevolution: study of evolution in populations ➔​Macroevolution: study of the development of new species and higher taxonomic levels ➔​A species is the smallest fundamental unit in the Linnaean Hierarchy and all individuals of a given type ➔​The Biological Species Concept ◆​A biological species is a group of organisms that are~ ​ (1) actually or potentially interbreeding and ​ (2) are reproductively isolated from other groups  ◆​Reproductive Isolation ​ The prevention of gene flow between populations by genetically determined differences between them ​ Something that prevents the act of mating or production of viable offspring other than physical separation ○​ Parts don't fit ○​ Different body sizes ○​ Different courtship rituals ○​ Genetic differences cause offspring to be sterile ➔​The Ecological Species Concept ◆​Emphasizes the role of natural selection in maintaining species boundaries ◆​Gene flow can occur but separate species are recognized because natural selection acts against hybrid individual ​ Can have hybrids but selection acts against hybrid individuals ➔​Modes of Speciation ◆​Allopatric Speciation ○​ “Allo” ~ different ○​ Different country ​ Some population is divided by some barrier and gene flow is interrupted ​ If separated long enough due to genetic drift, selection, or different environments, you have these differences that happen. ○​ When the barrier disappears they no longer are geographically isolated but reproductively isolated. ◆​Sympatric ○​ “Sym” ~ same ○​ Same country ​ No barriers ○​ Very rare; happens when there are two different morphs in a population and some  sort of reproductive isolating mechanism quickly takes hold. ◆​Parapatric ○​ “Para” ~ next to ○​ Next to country ​ Doesn’t require a barrier ○​ environment is varied enough that some phenotypes are favored in one environment and another phenotype is favored in another environment ​ Gene flow is reduced ○​ Acts as an isolating mechanism ➔​Cladogenesis: specialization by splitting of lineages ​ ​ ​ LOOK AT PICTURE IN SLIDES FOR THIS DEFINITION AND THE ONES FOLLOWING TO THE END ◆​Adaptive Radiation ~ ○​ special type of cladogenesis ​ A rapid series of multiple cladogenic events ​ Often occurs following the colonization of a new land mass ➔​Anagenesis: gradually transformation of one species into another ◆​Problem is how do you decide where to recognize a species' boundaries? ◆​When does species A change to species B? 2.12 Macroevolution Constructing Phylogenies ➔​Taxonomy: scientific classification (usually based on shared characteristics) ➔​Phylogeny: a model of presumed evolutionary relationships based on shared characteristics ➔​2 basic types of characteristics: ◆​Primitive ~ features shared by a group that are inherited from a more distant common ancestor ​ = Plesiomorphy ​ Hair is plesiomorphic for primates ◆​Derived ~ evolutionary innovations that evolved de novo in the group in question ​ = Apomorphy ​ Nails are apomorphic for primates ➔​Rules in Constructing Phylogeny ◆​Rule #1: ​ CAN’T use shared primitive characteristics (symplesiomorphies) to reconstruct evolutionary relationships, ONLY shared derived characteristics (synapomorphies) ◆​Rule #2: ​ Homoplasy is everywhere, makes reconstructing phylogenies difficult ​ Homoplasy ~ independent evolution of similar features in 2 or more lineages (usually in response to similar niche/ environmental pressures) ○​ ex. Bear and horse both have expanded hindgut and blunt teeth because they both eat a lot of vegetable matter ​ 3 types of homoplasy ○​ 1. Convergence  ◆​Evolution of similar structures using DIFFERENT anatomical features as a starting point ◆​Similar features resulting from convergent evolution are said to be analogous ​ ex. wings ○​ 2. Parallelism ◆​Evolution of similar structures using the same anatomical feature as a starting point ◆​Structure derived from the same evolutionary precursor are called homologous ​ ex. tails ○​ 3. Evolutionary Reversal ◆​Re-evolution of a plesiomorphic feature ​ ex. Re-evolution of claws in some primate clades (aye-ayes) ​ Claws are plesiomorphic for mammals ​ Nails are apomorphic for primates ​ Claws apomorphic for aye-ayes but look plesiomorphic ➔​Principle of Parsimony ◆​Assumes that features will evolve as few times as possible ◆​Minimizes homoplasy ◆​Parsimony = “stinginess” ➔​When you reconstruct phylogenies: ◆​1. Use only synapomorphies ◆​2. Employ the Principle of Parsimony ◆​Called cladistic methodology ➔​For living species, GENETIC synapomorphies ◆​Ex. Retrotransposons ~ sequence of DNA that can copy themselves (at random) and re-insert themselves (at random) in the genome  ​ Ex. Alu elements are retrotransposons found in primates and close relatives ○​ More than 65 MYA, a copy was transcribed into DNA and inserted in the genome of ancestors ○​ The problem with cladistics is homoplasy can mess thing up ◆​Alu elements are as close to a homoplasy-free marker as you can get Evolution of Social Behavior ➔​Primates are unusual mammals: the majority live in permanently mixed-sexed social groups. ◆​Costs and benefits to group-living ​ Increases potential for inbreeding ◆​Dispersal: immigration from a social group ​ Main effect if gene flow ​ Sex-biased dispersal: one sex disperses and one sex stays in the native group ○​ Males often disperse and females stay ○​ Get different combinations and patterns of how the genes move around the landscape ➔​Behavior influences the dispersion of allele frequencies in a population over time ➔​Natural Selection: ◆​Variation ◆​Heredity ◆​Differential Reproduction ➔​Evolution of Physical Traits ➔​Definitions: ◆​Reproductive Success: the number of offspring one produces that reach reproductive age ◆​Fitness: relative reproductive success ➔​How to increase Reproductive Success?  ◆​Increase through behavior ◆​Influence fitness ➔​Mating is a behavior with major genetic consequences ➔​Offspring care is a behavior with major consequences ➔​Selection should favor individuals who, on average, make choices that improve their fitness ➔​Reductionism? ◆​Evolutionary explanations are never couched solely in terms of low level phenomenon ◆​The genetic fitness of a behavior is the outcome of a decisions in the context of the whole range of the ecological demographic and social factors ➔​Behavior strategies are flexible ➔​One instrument of adaptation is in endocrine adaptation ➔​Changes in hormones and neurotransmitters can influence behavioral changes (mood, body shape, social bonding, risk taking, reproductive capabilities, and happiness) ➔​Is behavior genetically determined? ◆​Heritable variation and behavior does not equal genetic determinism ➔​Genotype: genetic composition of an individual ➔​Phenotype: the observed characteristics of an individuals reflecting the effects of the environment on genotypic expression ➔​Do you have to have genetic determinism? ◆​As long as behavior influences fitness, it can evolve. ➔​Phenotypic plasticity: the capacity of a single genotypic to produce multiple phenotypes in response to the environment ➔​Reaction Norm: the range of phenotypes that will be developed by a genotypes over a range of environments ◆​No plasticity ​ Small reaction norm ​ No variation ◆​Plasticity ​ Large reaction norm ​ Range of phenotypes that will be developed is much greater ◆​Types of Reaction Norms: ​ Irreversible Developmental Plasticity ​ Reversible Developmental Plasticity ➔​Bimorphism: 2 types of morphs of males ◆​Same genes ◆​Changing environmental input ➔​Sex as a reaction norm ◆​Sex attributes are phenotypically plastic ➔​Sex is a continuum, with effects of genes and environment on the phenotype resulting in sex determination, sex change, genitals, sexual characters, sexual behaviors, and mate choice and competition ➔​Genetic Determinism? ◆​Nature vs nurture ➔​Epigenetics ◆​stimulus/stress – methylation – gene expression – phenotype ◆​relationship of environmental stress to phenotype via an epigenetic mechanism that alters gene expression ◆​DNA Methylation: a biochemical process where a methyl group is added to cytosine or adenine DNA nucleotides. DNA methylation alters the expressions of genes in cells when cells divide and differentiate.