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Chapter 5. Macroevolution: Processes of Vertebrate and Mammalian Evolution. Chapter Outline. The Human Place in the Organic World Principles of Classification Definition of Species Vertebrate Evolutionary History: A Brief Summary. Chapter Outline. Mammalian Evolution - PowerPoint PPT Presentation
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Chapter 5Macroevolution: Processes of Vertebrate and Mammalian
Evolution
Chapter Outline The Human Place in the Organic World Principles of Classification Definition of Species Vertebrate Evolutionary History: A Brief
Summary
Chapter Outline Mammalian Evolution The Emergence of Major Mammalian
Groups Processes of Macroevolution
Classification Classification is used to order organisms into
categories to show evolutionary relationships. Example - human classification
Kingdom: Animalia Subkingdom: Metazoan Phyla: Chordata Subphyla: Vertebrata Class: Mammalia
Classification: Definitions Metazoa
Multicellular animals. Chordata
The phylum of the animal kingdom that includes vertebrates.
Vertebrates Animals with segmented bony spinal
columns; includes fishes, amphibians, reptiles, birds, and mammals.
Principles of Classification The field that specializes in establishing
the rules of classification is called taxonomy.
Organisms are classified first on the basis of physical similarities.
Basic physical similarities must reflect evolutionary descent in order for them to be useful.
Principles of Classification Homologies
Similarities based on descent from a common ancestor.
Analogies Similarities based on common function, with no
assumed common evolutionary descent. Homoplasy
The separate evolutionary development of similar characteristics in different groups of organisms.
Homologies
Two Approaches to Classification Evolutionary systematics
A traditional approach in which presumed ancestors and descendants are traced in time by analysis of homologous characters.
Cladistics Attempts to make rigorous evolutionary
interpretations based solely on analysis of certain types of homologous characters.
Ancestral and Modified Characters Ancestral characters
Refers to characters inherited by a group of organisms from a remote ancestor and thus not diagnostic of groups (lineages) that diverged after the character first appeared.
Derived characters Refers to characters that are modified from
the ancestral condition and thus are diagnostic of particular evolutionary lineages.
Approaches to Classification Evolutionary Systematics Cladistics
Goal Construction of a phylogenetic tree
Construction of a cladogram
Similarities
Compare specific traitsConstruct classifications to show evolutionary relationshipsFocus on homologies
Approaches to Classification Evolutionary Systematics Cladistics
Differences Might use any homologous characterAttempts to make ancestor-descendant links Attempts to place fossils in a chronological framework
Use only explicitly defined derived charactersNo attempt is made to make conclusions regarding ancestor-descendant relationshipsAll members of an evolutionary group are interpreted in one dimension
Definition of Species Biological species concept
Depiction of species as groups of individuals capable of interbreeding, but reproductively isolated from other such groups.
Speciation Process by which a new species evolves
from a prior species. Speciation is the most basic process in
macroevolution.
Speciation Model
Recognition of Fossil Species The minimum biological category we would like
to define in fossil primate samples is the species. Variations
Intraspecific - Variation is accounted for by individual, age, and sex differences seen within every biological species
Interspecific - Variation represents differences between reproductively isolated groups.
Recognition of Fossil Species Defining where species boundaries begin
and end is often difficult. “Splitters” are researchers who claim
speciation occurred frequently during hominid evolution.
“Lumpers” assume speciation was less common and see much variation as being intraspecific.
Recognition of Fossil Genera A genus is a group of species composed of
members more closely related to each other than to species from any other genus.
Species that are members of the same genus share the same broad adaptive zone.
Members of the same genus should all share derived characters not seen in members of other genera.
Geological Time Scale
ERA PERIODBegan m.y.a. EPOCH
Began m.y.a.
CENOZOIC
Tertiary 1.8 HolocenePleistocene
0.011.8
Quaternary 65
PlioceneMiocene
OligoceneEocene
Paleocene
523345565
Geological Time Scale
ERA PERIOD (Began m.y.a.)
MESOZOIC Cretaceous 136Jurassic 190Triassic 225
PALEOZOIC
PermianCarboniferous
DevonianSilurian
OrdovicianCambrian
280345395430500570
Geological Eras Paleozoic
The first vertebrates appeared 500 m.m.y.a. Mesozoic
Reptiles were dominant land vertebrates. Placental mammals appeared 70 m.Y.A.
Cenozoic Divided into two periods: Tertiary and
Quaternary and 7 epochs: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene and Holocene.
Continental Drift The movement of continents on sliding
plates of the earth’s surface. As a result, the positions of large
landmasses have shifted drastically during the earth’s history.
Continental drift The positions of the
continents during the Mesozoic (c. 125 m.y.a.).
Pangea is breaking up into a northern landmass (Laurasia) and a southern landmass (Gondwanaland).
Continental drift The positions of the
continents at the beginning of the Cenozoic (c. 65 m.y.a.).
Ecological Niches The positions of species within their
physical and biological environments, together making up the ecosystem.
A species’ ecological niche is defined by such components as diet, terrain, vegetation, type of predators, relationships with other species, and activity patterns, and each niche is unique to a given species.
Epochs Categories of the geological time scale. In the Cenozoic, epochs include
Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene
Mammalian Evolution The Cenozoic era is known as the Age of
Mammals. After dinosaurs became extinct, mammals
underwent adaptive radiation, resulting in rapid expansion and diversification.
The neocortex, which controls higher brain functions, comprised the majority of brain volume, resulting in greater ability to learn.
Lateral View of the Brain
Reptilian and Mammalian teeth
Mammals are heterodont, they have different kinds of teeth; incisors, canines, premolars, and molars.
Adaptive Radiation A process that takes place when a life form
rapidly takes advantage of the many newly available ecological niches.
A species, or group of species, will diverge into as many variations as two factors allow:
1. Its adaptive potential.2. The adaptive opportunities of the available
niches.
Major Mammalian Groups Monotremes
Primitive, egg laying mammals Marsupials
Infants complete development in an eternal pouch
Placental Longer gestation allows the central nervous
system to develop more completely
Quick Quiz
1. The scientific discipline that delineates the rules of classification is
a) paleontology.b) stratigraphy.c) homology.d) taxonomy.
Answer: d The scientific discipline that delineates the
rules of classification is taxonomy.
2. An advantage of heterodont dentition is that ita) allows the animal to defend itself more
efficiently.b) allows for processing a wide variety of
foods.c) opens up new ways of interacting with
potential mates.d) allows the animal to grab prey that it
could not catch otherwise.
Answer: b An advantage of heterodont dentition is
that it allows for processing a wide variety of foods.
3. The group of mammals that reproduce by laying eggs and who generally have more primitive traits than the other mammals are the
a) monotremes.b) metatherians.c) marsupials.d) placentals.
Answer: a The group of mammals that reproduce
by laying eggs and who generally have more primitive traits than the other mammals are the monotremes.
4. The divergence of reptiles into many different forms describes
a) analogies.b) sexual selection.c) adaptive radiation.d) homologies.
Answer: c The divergence of reptiles into many
different forms describes adaptive radiation.