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80 Cards in this Set
- Front
- Back
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Human Taxa
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1. Kingdom: Animalia
2. Phylum: Chordata 3. Class: Mammalia 4. Order: Primates 5. Suborder: Anthropoidea 6. Infraorder: Catarrhini 7. Superfamily: Hominoidea (end in “oidea”) 8. Family: Hominidae (end in “idae”) 9. Subfamily: Homininae (end in “inae”) 10.Genus: Homo 11.Species: sapiens |
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3 fundamental phases of Evolution
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• Production of genetic variation via mutation
and other genetic processes • Reduction of this variation primarily by natural selection • Species formation by reproductive isolation |
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Darwin’s Four Postulates
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1. Individuals in populations differ from one another
– Great phenotypic variation exists within populations. 2. Offspring resemble their parents – This variability is heritable. 3. Tendency to overpopulate results in a “struggle for existence” – More offspring are born than can possibly survive, and since population growth outstrips resource growth, competition for resources ensues. 4. Tendency for “best fit” variants to leave more offspring – Those individuals better suited to their environment (in whatever way) will survive longer and/or reproduce more, on average, than less well-suited individuals. |
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Stabilizing Selection
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Most selection is
stabilizing. It tends to prune off extremes, and favors average and intermediate |
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Directional Selection
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Directional selection
changes the variability. • Beak depth in finches changed after a drought –birds with deeper beaks were less likely to die because they could process large, hard seeds. • The peak of the distribution has shifted to the right. |
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Reproductive Isolation
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The last basic process of evolution– the
formation of a new species by reproductive isolation. All species will have numerous populations that live in different habitats. If gene flow gets restricted somehow between any of these populations and the main species, then that population may begin evolving new adaptations to the different habitat. • For example, an open country group gets separated and over the generations adapts to eating different food. |
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Reproductive Isolating Mechanisms
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Mechanical
– Reproduction may be physically impossible because reproductive organs no longer match. • Temporal – Two populations might be capable of interbreeding but they have developed different breeding seasons. • Behavioral – They might be capable of interbreeding but may have developed disparate mating behaviors. – For example, mallard ducks and pintail ducks hybridize in captivity but different mating habits keep them separate in the wild. • Mate Recognition – They may have diverged phenotypically to the point that they no longer recognize each other as mates. • Hybrid Inviability – Interbreeding may occur, but fail to produce viable offspring – For example, mules |
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microevolution
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The processes that produce genetic change
each generation are part of the study of |
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Macroevolution
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is the study of changes
observed through geological time and deals with trans-specific evolution. |
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How do we know if a fossil is intrusive (i.e., not
the same age as its strata)? |
Bones that are buried and covered by soil take up the
same proportion of Fluorine that is in the soil. • We can measure the concentration of Fluorine in the fossil and compare it to concentrations in other fossils buried nearby. • But it only works for fossils found at the same site. |
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Absolute dating
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methods allow us to estimate the age
of a fossil in a direct quantitative way. |
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Relative dating
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methods only allow us to say that a
fossil is older or younger than something else, or they may give us a probable range of dates for the fossil. |
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The most widespread absolute dating methods
consist of |
radiometric methods.
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Oxygen isotopes
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Oxygen occurs in 2 isotopes: 16O and 18O.
• The two forms weigh different amounts, and their ratio in deep sea cores tells us about what past climatic conditions were like. |
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Fossil primates are found as early as
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65 MYA..... but believed they existed 90 mya
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Suborder Prosimii
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prosimians
good clingers & leapers |
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Suborder Anthropoidea
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(monkeys, apes, people)
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Superfamily Hominoidea
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Apes and humans
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The Primate Suite of Characteristics (Ten)
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1. Clavicle (collarbone)
2. Grasping hands and feet 3. Five digits on hands/feet 4. Nails on at least one digit 5. Opposable thumbs/toes 6. Forward-facing eyes 7. Stereoscopic vision 8. Post-orbital bar 9. Reliance on vision as predominant sense 10. Enlarged brains for their body size |
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A long-standing hypothesis is that primate traits
evolved because of their |
arboreal lifestyle
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The Fovea
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Primates have a higher concentration of retinal ganglion cells
in the central retina. Anthropoid primates (and one prosimian, the tarsier) have a fovea in the retina. This gives us very sharp vision where we focus our visual attention. Primates have the sharpest visual acuity of all the mammals! |
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The superior
colliculus |
aka the
optic tectum) is in the midbrain, and is an ancient visual center. –It is involved in basic vision (e.g., flight or fight issues). |
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The Superior Colliculus
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Other mammals send
all their wires from one eye (and the entire visual field of that eye) to the opposite-sided (contralateral) SC. • Primates split the entire visual field of both eyes in half, and send the wires of each half to the opposite SC. • This helps stereoscopic vision because each SC gets input from both eyes. |
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Other mammals
send only a few of their wires from one eye to the samesided (ipsialateral) SC. But primates: |
Primates send a lot
more wires to the same-sided SC. In primates, they go to a larger part of the SC, along with the wires of the other eye. |
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Lateral Geniculate Nucleus
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The LGN is located
in the thalamus, in the forebrain. It has greatly expanded in primates. Although all mammals have an LGN, it is more complex and layered in primates. These layers have been well-studied and have different functions. The P layers are involved with red/green color vision, form vision, and object perception. • The M layers: motion detection • The K layers: blue color vision, perhaps unconscious vision and detection of danger. |
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V1
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It’s really good for
extracting details of images, e.g., lines, angles, and contours. |
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About half the
neocortex of primates is devoted |
Directly or indirectly to VISION
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The dorsal stream
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is
involved in spatial perception (where is it) and action: Vision for Action • The ventral stream is involved in object recognition (what is it): Vision for Assessment • These streams are unique to primates! |
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pulvinar
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located
near the LGN, in the thalamus of the forebrain. It has expanded hugely in primates. • It is well known for helping animals focus their attention on important objects in the environment. |
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The Arboreal Theory
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First primates lived high in the
canopies of tropical trees where the sense of smell is not particularly useful. • So primates lost much of their olfactory ability. The sense of smell was replaced by expansion of the visual sense, which was needed because primates had to be able to – judge distances when leaping from branch to branch and – coordinate the hands with the eyes to grasp branches. • Successful judgment of distances between branches would favor evolution of the eyes closer together toward the front of the face. |
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The Visual Predation Hypothesis
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He pointed out that many arboreal mammals
have good smell and not such good vision so living in the trees shouldn’t be a reason for losing olfactory ability and strengthening visual ability. • Rodents like squirrels do just fine in trees without primate vision So he modified it by arguing that only those predators that are nocturnal would need orbital convergence and forward-facing eyes in order to see clearly what is in front of them. |
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The Angiosperm/Omnivore Hypothesis
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• In 1991 Robert Sussman pointed
out that most nocturnal primates eat lots of fruit in addition to insects. • And those that eat insects often locate them by hearing and smell (not dependent on eyes). The most serious threat to the Nocturnal Visual Predation hypothesis was the problem of Old World fruit bats, however. • Fruit bats have visual systems that are very primatelike • They eat fruit! Sussman argued that the first primates were insect-eaters and fruit-eaters. • The first primates took advantage of the radiation of the flowering plants (angiosperms) that were spreading in warmer climates. • Flowering plants produce tasty fruits, nectar, and pollen, and the first fruits were small. • He suggested that finding such small foods in dim light was what required good eyesight. |
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The Camouflage-Breaking Hypothesis
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He argued that orbital convergence
is not necessary for good depth perception because other cues can be used, such as shading and perspective. Instead, Crompton argued that forward-facing eyes and grasping hands would have been better for finding small fruits and branches during travel. • He said that the need to zero in on small objects in a complex environment within the trees selected for expanded vision in primates. However, when you want to reach for something quickly and accurately, two eyes are better. |
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The X-Ray Vision Hypothesis
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Instead, they argue that convergent orbits
allow primates to see through vegetation They argue that for large animals, leaves get in the way and forward-facing eyes are needed to see through the leaves in cluttered environments, e.g., forests • They suggest that need to see as much as possible selected for expanded vision in primates. But the earliest primates were quite small. Teilhardina, the earliest known euprimate from N. America, weighed 1 oz (28 g)! • And they don’t acknowledge the importance of forward-facing eyes for speed and accuracy. |
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The Snake Detection Theory
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I suggested that the need to detect
predators, especially snakes, favored the evolution of visual changes in primates. • I also argued that not all primates have visually guided reaching and grasping, a key blow to nearly all other hypotheses. If visually reaching and grasping is a hallmark primate feature, then all primates should have that ability. • It’s clear that monkeys and apes have the ability. If galagos can’t adjust their reach once they’ve begun to move, what about other prosimians, the primates that most closely resemble early primates? • Lorises are indeed visual predators with good hand-eye coordination. • Lemurs often don’t use their hands for feeding at all, instead placing their mouths directly on the food. Instead, what early primates and fruit bats had in common is that they both benefited from good vision to deal with predators during the day. Only those fruit bats that sleep in lighted areas have primate-like neural connections in the visual parts of their brains |
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Paleozoic Era
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“the
old age of animals” (600-250 mya). |
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During the Cambrian, all major phyla living today
appeared and they showed up within a very short period or time, within a span of about 5 million years. This has been called the |
Cambrian
Explosion”. |
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Anomalocaris
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may
have been the largest predator in the Cambrian seas. |
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Light Switch theory
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vision
has been associated with predators-prey relationships for a very long time. Perhaps a change in the atmosphere allowed more light to penetrate into the oceans. |
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During the first part of the Paleozoic all life
seems to have lived in the |
Oceans
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During the Paleozoic
three classes of vertebrates evolved. |
Amphibians
• Reptiles • Fishes • No birds or mammals |
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Among the earliest reptiles was a
group called |
Pelycosaurs which were
probably on the line to mammals - long stabbing teeth |
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therapsids
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were reptiles, but had
some mammal-like traits. For example, they had limbs under the body. |
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Some Therapsids were truly
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heterodontsthey
had 4 different kinds of teeth Incisors , canines, premolars, molars |
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the
Mesozoic |
Beginning around 225
mya and lasting to about 65 mya |
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It is during the Mesozoic that the first
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Mammal appeared!!
Megazostrodon |
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Eomaia
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earliest placental mammal fossil
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The Mesozoic is called the
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Age of reptiles!
And first flowering plants! So insect species took off. And more species spread seeds |
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A burst of evolution like this
which leads to a large number of new, diverse forms is called an |
Adaptive radiation
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By the middle of
the Mesozoic... regarding the land masses |
Pangea breaks
up into Laurasia and Gondwana, separated by the Tethys Seaway |
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The Mesozoic seems to have been fairly
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warm until just at the end when a rapid
cooling event occurred. And meteor Which led to extinctions |
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In all, about half of all genera living at the time
perished at the Mesozoic/ Cenozoic line 65 my ago. This time/event is called the |
K-T boundary
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Triconodont molars appear to be like those from which
all later mammalian molars evolved – They had |
three cusps in a row
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The Paleocene was warm and lovely with
temperatures at 50-70° F in the temperate zone Tropical Ecosystems were found in the |
Arctic Circle
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The Paleocene is the
first epoch (of 7) of the Cenozoic, often called |
the age of mammals
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Altiatlasius
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Paleocene
10 isolated teeth • Upper molars with broad trigons • Lower molars have low trigonids • and broad talonid basins, a basic mammalian tooth shape |
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It is by the ______ times
that we see some primates that look more like the familiar forms of today. |
Eocene
These ones All of these primates had nails instead of claws, unlike the majority of the plesiadapiforms. • They also had opposable big toes. |
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Skulls of the eocene primates
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• Snouts are reduced relative to the plesiadapiforms
• Eyes shifted more forward with a post-orbital bar • Brains are becoming larger |
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At the beginning of the Eocene (~55 mya), N. America
and Europe |
were connected - immigration
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But by the latemiddle
Eocene the temperature began to |
decline rapidly.
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By ~___ my the land link between Europe and N.
America ends. From this point on mammalian fauna become remarkably distinct on these continents. |
48
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Plant life in the eocene
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There was lush vegetation including relatives of
a variety of trees such as sycamores, poplars, laurel, walnuts, and hazelnuts. |
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There are two fundamentally different
kinds of Eocene primates |
The lemur-like
adapoids and the tarsier-like omomyoids |
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omomyoids
Snout, eyes, teeth |
Short Snout, Big eyes, large incisors
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adapoids
Snout, eyes, teeth |
Long snout, small eyes, small incisors
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The Omomyoidea probably includes
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Altiatlasius of the Paleocene
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Adapoids and lemurs do, however, have a few
synapomorphies: |
small and spatulate upper
incisors, derived ankles and wrists, and a grooming claw on the second toe. |
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But adapoids were unlike lemurs in two critical
respects: |
Adapoids had no tooth comb.
• They usually had a fused mandibular symphysis (lemurs and lorises are unfused). |
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Cantius
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Superfamily Adapoidea
the earliest and most primitive of the adapoids. • |
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By mid-Eocene times there was a global cooling and
many areas became open woodland. During this time: At least 20 mammalian lineages evolved the |
hypocone and the
capacity to grind fibrous vegetable matter. |
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Notharctus
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anapoid.. Descendant of Cantius
• 2.1.4.3 dental formula • Fused mandibular symphysis • Well-developed hypocone Mandibular dentition • Molars with four cusps |
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Families of the Superfamily Adapoidea:
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Family Notharctidae (e.g., Cantius,
Notharctus, Darwinius) • Family Adapidae (e.g., Adapis) • Family Sivaladapidae (Sivaladapis) |
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Adapis
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Superfamily Adapoidea
Long snout • E.Q. (brain to body mass ratio) = 0.58 • Lemur-like basicranium (base of the braincase) • Folivore • 2.1.4.3 Lacks heel bone |
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Sivaladapis
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Miocene
2.1.3.3 • Odd combination of specialized traits such as upper molars with no hypocone, molarized P4 • Fused mandibular symphysis, no tooth comb. • Extinct side branch |
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Superfamily Lemuroidea:
Five extant families entirely limited to Madagascar |
• Lemuridae (lemurs)
• Cheirogaleidae (dwarf and mouse lemurs) • Lepilemuridae (sportive lemurs) • Indriidae (indris, sifakas) • Daubentoniidae (aye-aye) |
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Family Lemuridae
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Live in dry south of
Madagascar • Live in large social groups • No sexual dimorphism |
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Family Cheirogaleidae
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the
mouse lemur • Small • Nocturnal • Solitary |
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Family Lepilemuridae
Genus Lepilemur |
Lepilemur is:
• A folivore • Missing both upper incisors (0133/2133) • Caecotrophic like a rabbit (excretes and feeds on the contents of the caecum) |
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Family Indriidae
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Indriidae have
reduced dentition: – 2123/2023 • Indriidae are super clingers and leapers with long hindlimbs |
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Family Daubentoniidae
Genus Daubentonia, the aye aye |
Few teeth (1013/1003)
•Rodent-like incisors • Insecting claw on third digit of the hand |
