Announcements and summary*Oct 12 (changed to the Wednesday) = Quiz 2

*Oct 19 = Midterm Essay due and MUST bring in hard copy of essay

Midterm - 3x5 flash card

*Quiz key on website and others things on website

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Quiz 2 Potential Short Answer Questions1. Define and compare two of the five processes of evolutionary change.

2. Pick one of the distinctive features of distinguishing mammals from other land animals and explain how it contributed to the mammalian diversification in the Late Mesozoic-Early Cenozoic.

3. Describe the modern Biological Species Concept used in cladistics and other classification systems.

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Announcements and summarySummary

*Recap important topics from last time*Paleopecies*Classification in light of modern evolutionary change

https://creasonanthro.wordpress.com/anthr-1-fall-lbcc/

*Note: I explain species (105p) first and then follow the order of the chapters starting on page 97.

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Ch 5 Macroevolution

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Modern Evolutionary TheoryMacroevolution - long-term over geologic time synonymous with speciation

Focuses on large-scale evolutionary processesSynthesize our understanding of modes of evolutionary change, geologic time, and taxonomic classification

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Species ConceptsBiological Species Concept - BSC - Species boundaries form due to reproductive isolation-New species form due to some type of isolation-The accumulated effects of drift and natural selection are emphasized

Speciation - Most basic process of macroevolution - process through which new species emerge from earlier species

Various types of isolation - geographical, behavioral, reproductive

Kingdom > Phylum > Class > Order > Family > Genus > Species

Ex: K: Animalia > Ph: Chordata > C: Mammalia > O: Primates > F: Hominidae...

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Principles of ClassificationHomologies - Structures shared by species due to common descent

Analogies - similar structures arise in other lineages in response to different functional demands

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Systematics and CladisticsBoth-Use homologies trace evolutionary relationships

Differ-Primary difference - Cladistics are more explicit and rigorous

Systematics - use phylogenetic trees illustrating evolutionary relationships-incorporates time (cladograms do not)-rely on hypothesized relationships between groups linked by common ancestors (cladograms do not)

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Cladistics more explicit and rigorous -looks at ancestral versus derived traits

Clade - lineages sharing a common ancestor

Ancestral traits - traits shared via common distant ancestry-trait is shared between two different species and their common ancestor-better for broader comparisons and identifying large evolutionary groupsEx. Grasping hand in humans, nonhuman primates and our last common ancestor

Derived traits - infer evolutionary lineages because they are modified from the original ancestral traits-better for distinguishing one evolutionary group from another-cladistics focuses on these traits; clades are identified and differentiated through these traits.Ex: Land vertebrates possess a general ancestral forelimb pattern but their modifications in different groups helps us distinguish between the groups

Cladistics needs to be careful of homoplasy

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Variation in the fossil recordCladistics and the fossil record-Individual variation - the variation seen in an individual's phenotype due to recombination

-Age change variation - some fossil forms have deciduous teeth (20) while others are matured to having permanent teeth (32)

-Sexual dimorphism - physical characteristics differ between males and females

Remember these variables to avoid errors.

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Intraspecific - variation = individual, age, sex differences within species-If variation in fossils compares to related extant organisms, then disignate single species

Interspecific - such variation represents differences between species

Splitters - speciation occurred more often

Lumpers - more likely intraspecific variability

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Types of variation continued

Identifying paleospecies-grouped by the clusters of derived traits-use living species as proxy

Concerns-variation spatially (over space) and temporally (through time) -fossils separated by millions of years.-expanded time frame = more dynamic image of species morphology-blurs taxonomic boundaries-Still a disputed process because of the concern with homoplasy

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Fossil Genera-a genus has at least 2 species that are distinct from each otherExtinct genera -share adaptative zone.

Adaptive zone = broader than ecological niche or econiche which are used to identify individual species.

Ecological niche = position of a species in a physical/environmental context-diet, terrain, vegetation, predation, interaction with other species, etc.

Anthro Ex: Fossilized primate teeth

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Fossils and fossilization processesFossils are traces of ancient organisms manifested through various physical processes

-Most fossil evidence = pieces of shells, bone, teeth - basically the hard parts of an organism

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Fossils and fossilization processesMineralization - After an organism dies the hard tissues become impregnated with other minerals and eventually solidify

Insects are trapped in tree sap - hardens over time. The lack of oxygen results in very well preserved insects (we can extract DNA from them!).

Impressions of leafs/things left in clay which hardens into stoneAnthr Ex. 47 mya well preserved primate skeleton with soft-body imprint and fossilized remains associated with the digestive tract (Franzen et al 2009).

Footprints from dinosaurs and early Hominins, too, are preserved

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Fossils preservationPreservation depends on how and where the individual diedMarine fossils are more frequent than land fossil organisms

Land - postmortem the circle of life leaves nothing left of the individual to fossilize-Need rapid sedimentation to cover up the individual or volcanic ash

Taphonomy = study of how fossils are preserved - look at bone preservation and sedimentary processes

Teeth = hardest, most durable portion of vertebrate skeleton and so they're most likely to mineralize

Most available fossil data is inferred from teeth - including primates

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Vertebrate evolutionGeologic time scale - Eras > Periods > EpochsCenozoic era has two periods: Tertiary and Quaternary-seven epochs: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and the recent epoch: Holocene

Vertebrate evolution spans Paleozoic, Mesozoic, and the Cenozoic eras

Fish ~500 mya in the Paleozoic (earliest out of reptiles, mammals, and birds)

Mammal-like reptiles ~250 mya - diversify in Late Paleozoic

Reptiles/dinosaurs ~252 mya = most dominant land vertebrates cf Mesozoic -expanded into a wide array of econiches

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Vertebrate Evolutionary history

Geographical changes in Paleozoic and Mesozoic influenced vertebrate evolution

Continental drift = continents move like sliding plates on the Earth's surface-Large landmasses shifted dramatically throughout geologic time-Induces volcanic activity (Pacific Rim); mountain building (Himalayas); earthquakes

Pangea - late Paleozoic singular land mass but large chunks split to the north and south in the early Mesozoic ~65 mya-isolated by oceans => distributed mammals and other land vertebrates

-Continental drift is still happening today - slow process (uniformitarianism)

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Rise of the mammals

Fish ~500 mya in the Paleozoic (earliest out of reptiles, mammals, and birds)Mammal-like reptiles ~250 mya - diversify in Late PaleozoicReptiles/dinosaurs ~252 mya = most dominant land vertebrates cf Mesozoic -expanded into a wide array of econiches

Mammalian Evolution ~75 mya diverged according to fossil and DNA-mammals and birds replaced reptiles as the dominant land-living vertebrates-rapid growth ~late Mesozoic/early CenozoicMajor Mammal Groups*Monotremes - egg-laying = most ancestral*Marsupials - pouched = immature young complete development in external pouch*Placental - long development period in utero and placental tissue specialized to provide nourishment

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Distinctive mammalian featuresLarge brains - selected for information processing but required longer, more intense periods of growthEx. cerebrum enlarged - trend continued to increase in primates

Placental - give live birth another innovation widespread by the CenozoicLonger in utero development - central nervous system to develop more completelyInternal development in particular was a major innovation for land vertebrates

Heterodont - ancestral mammalian teeth patterns:3 incisors, 1 canine, 4 premolars, 3 molars = process a wide variety of foods

Endothermic - maintained constant internal temperature thru metabolic activities 20

Adaptive Radiation-operates on species over geologic time-branching evolution

Adaptive radiation - when groups find new niches while competing for available resources and increase reproductive successOver time more species emerge and diversify-Responsible for the great diversity of lifeAdaptive potential and Adaptive opportunities of the available niches

Ex. Little diversity in reptiles until more efficient hard shelled eggs (adaptive potential) emerged allowing them to venture inland to fill-in new niches

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Macroevolutionary process: Adaptive RadiationEx. Rapid expansion of mammals cf late Mesozoic and the Cenozoic resulted from a massive extinction event at the end of the Mesozoic left many econiches for the mammals to fill up

The once small-bodied, nocturnal mammals no longer had to compete with dinosaurs and filled their econiches

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Generalized and Specialized Characteristics Adaptive radiation = transition from generalized characteristics to specialized onesTerms refer to the adaptive potential of a particular traitGeneralized = trait adapted for many functions - usually ancestralEx. Generalized mammal limb with five flexible digits several different functions

Specialized = limited to narrow set of functions - usually derivedEx. Hominin feet evolution

NOTE: Generalized ancestral characteristics are the only way to give flexible evolutionary springboard for rapid diversification which leads to specialization to certain econiches

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Early Primate Evolution - Miocene HominoidsAnthro Ex.-Macroevo: Species of early hominins ~4 mya from a common ancestor with Pan resulted in some species adapting to ground-living niches-Microevo: Few thousand years modern human populations adapted to living at high altitudes became possible due to changes in certain genes.

Tempo -species change both gradually and in punctuated eventsAnthro Ex. Old World Monkeys speciate slower compared to rates seen in the great apes

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Early Primate Evolution - Miocene Hominoids

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Evolutionary Histories - Vertebrates*Fish = earliest form of life out of dinos, mmls, reptiles, birds, and fish*Monotremes = mammals who evolved first - emphasis on mammals*Go over taxonomy*Get them to understand fossils: amber insect, mineralized body of a trilobite, footprints, impressions that are now stone*66mya an asteroid caused a mass extinction event*Analogies (our bipedality and ostriches)*Adaptive radiation - period of rapid evolutionary disversification in order to fill vacant evo nichesCladistics = newer and more rigid taxonomic system of classification

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Modern Evolutionary Theory*Fish = earliest form of life out of dinos, mmls, reptiles, birds, and fish*Monotremes = mammals who evolved first - emphasis on mammals*Go over taxonomy*Get them to understand fossils: amber insect, mineralized body of a trilobite, footprints, impressions that are now stone*66mya an asteroid caused a mass extinction event*Analogies (our bipedality and ostriches)*Adaptive radiation - period of rapid evolutionary disversification in order to fill vacant evo nichesCladistics = newer and more rigid taxonomic system of classification

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