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 1
Quiz 2 Potential Short Answer Questions 1. 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. 2
Announcements and summary Summary *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. 3
Ch 5 Macroevolution 4
Modern Evolutionary Theory Macroevolution - long-term over geologic time synonymous with speciation Focuses on large-scale evolutionary processes Synthesize our understanding of modes of evolutionary change, geologic time, and taxonomic classification 5
Species Concepts Biological 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... 6
Principles of Classification Homologies - Structures shared by species due to common descent Analogies - similar structures arise in other lineages in response to different functional demands 7
Systematics and Cladistics Both -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) 8
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 groups Ex. 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 9
Variation in the fossil record Cladistics 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. 10
Types of variation continued 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 11
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 12
Fossil Genera -a genus has at least 2 species that are distinct from each other Extinct 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 13
Fossils and fossilization processes Fossils 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 14
Fossils and fossilization processes Mineralization - 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 stone Anthr 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 15
Fossils preservation Preservation depends on how and where the individual died Marine 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 16
Vertebrate evolution Geologic time scale - Eras > Periods > Epochs Cenozoic 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 17
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) 18
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 Paleozoic Reptiles/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 Cenozoic Major 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 19
Distinctive mammalian features Large brains - selected for information processing but required longer, more intense periods of growth Ex. cerebrum enlarged - trend continued to increase in primates Placental - give live birth another innovation widespread by the Cenozoic Longer in utero development - central nervous system to develop more completely Internal 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 success Over time more species emerge and diversify -Responsible for the great diversity of life Adaptive 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 21
Macroevolutionary process: Adaptive Radiation Ex. 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 22
Generalized and Specialized Characteristics Adaptive radiation = transition from generalized characteristics to specialized ones Terms refer to the adaptive potential of a particular trait Generalized = trait adapted for many functions - usually ancestral Ex. Generalized mammal limb with five flexible digits several different functions Specialized = limited to narrow set of functions - usually derived Ex. 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 23
Early Primate Evolution - Miocene Hominoids Anthro 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 events Anthro Ex. Old World Monkeys speciate slower compared to rates seen in the great apes 24
Early Primate Evolution - Miocene Hominoids 25
Early Primate Evolution - Miocene Hominoids 26
Early Primate Evolution - Miocene Hominoids 27
Early Primate Evolution - Miocene Hominoids 28
Early Primate Evolution - Miocene Hominoids 29
Early Primate Evolution - Miocene Hominoids 30
Early Primate Evolution - Miocene Hominoids 31
Early Primate Evolution - Miocene Hominoids 32
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 niches Cladistics = newer and more rigid taxonomic system of classification 33
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 niches Cladistics = newer and more rigid taxonomic system of classification 34