Primate Adaptation Lab- STUDENT_updated June 2023

1 YOUR NAME: Dane Haehn LAB SECTION: PRIMATE ADAPTATION Objectives: • Identify different primate locomotor styles and the limb proportions associated with them • Relate skeletal differences among primates to their locomotor behavior • Describe how tooth form and body size relate to diet in primates Background knowledge: Primates are diverse in their body sizes, diet, and locomotor behaviors. The smallest primate, a mouse lemur, weighs between 30 and 100 grams (0.2 pounds), while the largest primate, a gorilla, can weigh as much as 450 pounds. This lab will introduce you to the variety of primate diets and locomotion, and will demonstrate how these two behaviors are linked to body size. Primates are broadly characterized as insectivores , folivores (leaf-eaters), and frugivores (fruit eaters), but some taxa also rely on exudates (gums and saps) as a food source (exudativory). Small-bodied primates tend to be insectivorous because of high basal metabolic requirements, while large bodied primates tend to be folivorous. Medium-sized primates are often frugivorous. In addition, insects, leaves, and fruit all have different mechanical properties that require different kinds of teeth to process them. Insectivores have teeth with high, sharp cusps to crush the hard exoskeleton of insects, while frugivores have teeth with low, round cusps to grind fruit into a pulp. Folivores have teeth with sharp shearing crests, which are used in a scissor-like fashion to reduce leafy material to small pieces that the gut can digest easier. In terms of locomotion, primates are generally characterized as quadrupedal, leaping, suspensory or bipedal . Quadrupedalism is the use of all four limbs on the tops of branches or on the ground, and includes arboreal quadrupedalism , terrestrial quadrupedalism , and knucklewalking . Leaping can either be done quadrupedally or in a specialized form called vertical clinging and leaping , which involves clinging to tree trunks and leaping from tree to tree. Leapers and bipeds rely on their lower limbs (also called hindlimbs) to provide the propulsive force during locomotion, while suspensory taxa rely mostly on their upper limbs (also called forelimbs). Quadrupeds emphasize the upper and lower limbs roughly equally. These differences in locomotor mode result in skeletal differences among taxa. Although there are many skeletal adaptations to locomotion, some examples include the lengths of the fore- and hindlimbs, the position of the fore- and hindlimbs in relation to the body, the shape of the ribcage, and the position of the foramen magnum.

2 Station 1. Primate Locomotion Watch the set of video clips of primate locomotion and answer the following questions. • Read the questions first so that you can watch the videos with the questions in mind. • Use the bold terms on page one for your answers regarding locomotor behaviors. 1) Hoolock gibbon ( Hoolock hoolock) : (body mass: 8 kg) a. Which locomotor behavior do these apes rely on? Brachiators b. Do these apes have longer forelimbs, longer hindlimbs, or roughly equal limb lengths? Longer forelimds 2) Hamadryas baboon ( Papio hamadryas ): (body mass: 15-30 kg) a. Which locomotor behavior do these monkeys use? Terrestrial quadrupedal b. Do these monkeys have longer forelimbs, longer hindlimbs, or roughly equal limb lengths? Equal limb length 3) Chimpanzees (Pan troglodytes ): (body mass: 50 kg) a. Which locomotor behavior(s) do chimps use when in the trees? Suspensory brachiation b. Which locomotor behavior do chimps use when they are on the ground? Be as specific as possible. Knuckle walk c. Do these apes have longer forelimbs, longer hindlimbs, or roughly equal limb lengths? Roughly equal limb length

4 Station 2. Locomotion and Intermembral Index The relative length of forelimb to hindlimb (intermembral index) reflects locomotor patterns. Measure the limb bones and calculate the intermembral index for each illustrated primate using the formula below. IM = length of humerus + length of radius x 100 length of femur + length of tibia 1) Siamang ( Symphalangus syndactylus ), a suspensory and brachiating primate. 141 2) Indri ( Indri indri ), a vertical clinger and leaper. 67 3) Rhesus macaque ( Macaca mulatta ), a terrestrial quadruped. 97 4) Human ( Homo sapiens ), an obligate terrestrial biped. 68 5) Based on your measurements and what you learned in lecture, what is the association between intermembral index and locomotor pattern? Make sure to explain your reasoning. The intermembral index measures limb proportions by comparing hindlimb length to forelimb length. A high index (greater than 100) often signifies running adaptations (cursorial), while a low index (less than 100) indicates climbing adaptations (arboreal).

5 Station 3. Primate Diets: Kay’s Threshold This chart lists the calories and grams of protein per cup (volume) of different foods that primates might eat. Food Calories Protein (g) Mealworms 1.4 each 0.09 each Beef 413 per cup 38 per cup Large Grasshopper 9 each 0.65 each Cashews 885 per cup 27 per cup Chestnuts 373 per cup 11 per cup Breadfruit 265 per cup 2.5 per cup Banana 333 per cup 0.4 per cup Figs 134 per cup 0 per cup Kale 21 per cup 2 per cup Spinach 7 per cup 0.9 per cup Celery 30 per cup 2 per cup This chart provides estimates for weight and ROUGH corresponding estimates for necessary daily caloric and protein intake. Keep in mind that these are ROUGH estimates and may not be accurate, and are only to be used for the purposes of completing this lab. Animal Weight (lbs) Weight (kg) Estimated calories needed per day Estimated protein needed per day Mouse 0.06 0.03 10 1 Hamster 0.25 0.11 40 4 Rat 1 0.45 45 4.5 Small Cat 5 2.3 200 20 Big Rabbit 14 6.4 560 56 Dog 50 23 1500 150 Goat 90 41 1350 135 Human 150 68 2250 225 Gorilla 200 91 3000 300 ***Use these charts to answer the following questions on the next page.***

7 3) Refer to the chart to see how much a gorilla weighs. a. How many large grasshoppers would a gorilla have to eat in a day to meet its protein requirements? Would this meet its caloric requirements? 461.5 cups of grasshoppers Yes it will meet requirements b. How much celery (volume) would a gorilla have to eat in a day to meet its protein requirements? Would this meet its caloric requirements? 150 cups of celery, yes it would meet c. Which of these foods is a gorilla more likely to be able to get in sufficient quantities to meet its protein and caloric requirements? Why? Yes, because you can eat less celery and meet requirements

8 Station 4. Teeth and diet At this station examine the different kinds of teeth from the skulls of a tarsier ( Tarsier sp.), gorilla ( Gorilla gorilla ), and a gibbon ( Hylobates lar ). Observe the sharpness of the crests and cusps and the overall shape of the teeth. Both leaves and insects require high, sharp shearing crests and tall, pointy cusps in order to extract the most energy from these food sources; low, flat, grinding cusps and short, rounded crests usually work best with fruits. Use the bolded terms above to describe the shape and size of each primate's tooth. Tarsier: (premolars and molars) high, sharp shearing crests Gibbon: (molars) low, flat, grinding cusps Gorilla: (molars) tall, pointy cusps Based on what you have observed in their dentition and what you know about their body sizes , what do you think are the significant dietary portions of the gibbon, langur, and mouse lemur? For each species, check one box corresponding to its presumed diet. Fruit Insects Leaves Tarsier yes yes Gibbon yes yes yes Gorilla yes yes

10 Station 6. Primate Hand Morphology At this station are hands of several primate species: • The gibbon ( Hylobates ) is a suspensory primate living in the forests of Southeast Asian. • The macaque ( Macaca ) is a terrestrial quadruped that lives in Asia. • Chimpanzees ( Pan troglodytes ) live in forest and savanna habitats in western and central Africa. They are suspensory in the trees and knuckle walk on the ground. Compare the hand of the gibbon, macaque, and chimp and complete the table below. The two characteristics you will be looking at for each species are: • Phalangeal curvature refers to the degree of curvature in the phalanges. • Relative Phalangeal length is the length of the proximal, intermediate, and distal phalanges comprising the finger (make sure you are taking into account differences in body size). Table 1. Primate Hands Taxon Phalangeal Curvature (straight or curved) Relative Phalangeal length (long, intermediate, or short) Gibbon ( Hylobates ) Body weight: 6-12 kg Macaque ( Macaca ) Body weight: 5-18 kg Chimpanzee ( Pan ) Body weight: 40-60kg 1. Formulate a hypothesis about the relationship between locomotion and phalangeal curvature . Using data from the information above explain why you have proposed this hypothesis. 2. Formulate a hypothesis about the relationship between locomotion and phalangeal length . Using data from the information above explain why you have proposed this hypothesis.