Study objectives from Exam 11. What is “natural selection”? How does it work? What is “fitness”?Natural Selection: the process by which some organisms, with features that enable them to adapt to their environment, preferentially survive and reproduce, thereby increasing the“fitness” of those features in the population. Three criteria of natural selection: 1) variability 2) heritability 3) differential success in surviving/reproducing Reproductive Fitness: probability that a given trait will spread in the population (relative to the present environment) 2. What is an adaptation?Natural selection “in action” Pod Kopiste island: Pod Mrcaru Island:~insectivore, small head ~herbivore, large head 3. What are the four “forces” (mechanisms) of evolution? How does each contribute to variation within and between (among) populations? The four forces of evolution: 1) mutations- the only source of new variation (alteration ofDNA sequence~change in resulting protein). 2) natural selection-types of selection (directional, stabilizing, disruptive). 3) genetic drift-small population size or “Founder’s effect” (random shift in allele frequencies). 4) gene flow- exchange of genes between populations (exogamy:reduces variation between populations; endogamy: increases variation between populations ~inbreeding). Study Objectives for Chapters 6 and 71. Be able to classify humans (Homo sapiens) according to the Linnaen system (Handout).Kingdom (Animalia)Phylum (Chordates) ~SubPhylum (Vertebrates)Class (Mammals)Order (Primates) Family (Hominids) Genus (Homo)Species (Sapiens)2. What is sexual selection? How does sexual selection in primate results in sexual dimorphism?Sexual Selection: the frequency of traits that change due to those traits’ attractiveness to members of the opposite sex. Sexual Dimorphism: A difference in a physical attribute between the males and females of a species. Sexual Selection leads to Sexual Dimorphism through social/mating systems- Solitary: female/offspring (orangoutangs, and some nocturnal strepsirhines). Polygynous: one male/ multiple females “harems” or multi male/multi female-dominance hierarchies, competition for mates. Monogamy (pair bonding): paternal investment, little competition-low sexual dimorphism (gibbon). Polyandry: rare (marmosets) infant care (twins*). 3. What are the four “trends” that characterize primates? What primate adaptations are associated with each trend?1) Adaptations to arboreal life: flexible skeletal structure, grasping hands and feet, opposable thumb, big toe, nails, and dermal ridges. 2) Reliance on vision: post orbital bar, stereoscopic and color vision. 3) Dietary Plasticity: heterodont, variable diets-fruit.4) High dependence on Learning: large brains-relative to body size, extended growth stages, high sociality. 4. Know the primate classification and basic characteristics of each group in that classification Strepsirhines (lemurs and lorises): Madagascar, Africa, Asia-small, many insectivorous, tooth comb, many are nocturnal, reliance of smell “rhinarium” (wet dog-like nose). Haplorhines (tarsiers, monkeys, apes, humans). Tarsier: Malaysia-resemble Strepsirhines, small, nocturnal, insectivore, no “rhinarium,” loss of tapedum lucidum (share derived traits with monkeys, apes, and humans). Old World Monkeys (baboons, macaques): Africa, Asia- large, some arboreal, some terrestrial, large groups, complex social interaction. New World Monkeys (marmosets, spider monkeys): South and CentralAmerica- mostly diurnal (except owl monkey), all arboreal, three premolars, some have prehensile tail (spider monkeys). Hominoids (gibbons, orangutans, gorillas, chimpanzees, bonobos, humans): South East Asia, Africa-large, loss of tail. 5. Be familiar with the following terms and concepts:Stereoscopic vision: the eyes are on the front of the head. Dental formula: the numerical description of a species’ teeth; listing the number, in one quadrant of the jaws, of incisors, canines, premolars, and molars. Post-orbital bar: lines the back of the eye orbit but does not fully enclose it. Post-orbital closure: the eye orbit is fully enclosed. Home range: territory. Dental (tooth) comb: in modern lemur species, the lower incisors form a dental comb thatprojects horizontally from the mandible. Insectivorous: the practice of eating insects. Folivorous: the practice of consuming leaves. Frugivorous: the practice of eating fruits. Omnivorous: the practice of consuming a wide range of plants and animals. Suspensory: the form of locomotion in which all four limbs grasp onto branches to help move from one tree/branch to another. Quadrupedal: the form of locomotion in which all four limbs are relatively the same size and help move terrestrially. Leaper: the form of locomotion in which the hind limbs are longer than the front which allow them to “leap” from on tree/branch to another. Knuckle-walker: the very strong arms are used to support the upper body weight, while positioned on the backs of the fingers’ middle phalanges; the knuckles bear the weight, while fingers are flexed toward the palms. Brachiation: primates which use their upper limbs to move from one tree limb to another. Monogamy: one male paired with one female. Polygyny: one male with multiple females (harems) or multiple males with multiple females (dominance hierarchy). Polyandry: rare (marmosets) infant care (twins). Cusp: the chewing surface of the molar. Diurnal: active during the day. Nocturnal: active only at night. Prehensile (grasping): a tail that acts as a kind of hand for support in trees, common in New World Monkeys.Tapetum Lucidum: a layer of tissue in the eye of many vertebrate animals, that lies immediately behind or sometimes within the retina. It reflects visible light back through the retina, increasing the light available to the photoreceptors. Neocortex: the outer layer of the cerebral cortex found in the brain of mammals. 6. What are Darwin’s four “hostile forces”? What physical and behavioral traits have primates evolved in response to these selective forces? What anatomical correlates can beused to infer these adaptations in extinct primates? %6.Environment: Diurnal/nocturnal-vision vs. Smell/hearing Eye Socket Size. Arboreal vs. Terrestrial -body size, locomotion(suspensory, leapers, quadrupeds, knuckle-walkers)