Transcript Chapter 19 Macroevolutionary Puzzle

Chapter 19
Macroevolutionary Puzzle
Introduction 
• Geologic time requires time measured in
almost incomprehensible lengths
• We have dated asteroids impacts and their
consequences, such as dinosaur extinctions
Fossils:
• Are recognizable, physical evidence of
organisms that lived long ago– skeletons,
shells, leaves, seeds, imprints of leaves an
tracks an even fossilized feces
• Conditions necessary for fossils:
– Hard parts
– Buried quickly (absent of oxygen)
– Free from decomposers and scavengers
Fossils in Sedimentary Rocks
• Relative Dating
– Stratification, the layering of sedimentary deposits
bearing fossils, is quite similar from continent to
continent.
– Deepest rock strata are assumed to be the oldest,
surface layers the youngest.
– Abrupt changes in the fossils in the layers wer the
basis for dividing earth history into great era,
which formed a “geologic time scale” to which
actual dates were added later.
Interpreting the Fossil Record
• The fossil record is far from complete, but
some lineage are extensive.
• Fossil records vary according to type of
organisms, stability of the geographical region,
and quality of the specimen
Macroevolution
• Refers to large-scale evolutionary changes that
take place over long time periods.
• Speciation is the splitting of one species into
two or more species or the transformation of
one species into a new species over time;
speciation is the final result of changes in gene
pool allele and genotypic frequencies.
Absolute Dating (Radiometric Dating)
• To determine the actual age of the fossil
through isotopes in the fossils or rocks
• Half-life: the time its for half the radioactive
isotopes to break down
– Examples:
• Carbon-14 will break down to nitrogen-14 (useful with
fossils up to 50,000 years old)
• Uranium-256 will break down to lead-206
Theory of Uniformity
• Mountain building and erosion had repeatedly
changed the surface of the Earth in exactly the
same ways through time
Continental Drift
• Alfred Wegener proposed a model of a single
continent, named Pangaea, that at one time
extended from pole to pole surrounded by a
single huge ocean.
• The idea of continental drift explains the
separation of the continents and the
formation of great mountain ranges as the
continents collided
– Appalachian Mountains formed when Africa and
North America collided
Continue…
• Evidence of continental drift
– Magnetic alignment (magnetic North was
switched throughout the Earth’s history)
– Coal seams (Indicates North America was in the
was in a warm swampy environment)
– Glacial Deposits
– Fossils (Found in different continents)
Continue…
• Sea-flooring spreading and plate tectonics also
show that the Earth’s crust is moving
– Divergent Boundaries: Plates separating together
(Atlantic Ocean)
– Convergent Boundaries: Plates coming together
(Pacific Ocean)
Comparative Morphology
• Provides evidence of evolution by comparing
anatomical features to reveal similarities and
differences
– Also known as homologous structure
Morphological Divergence
• Features that have departed in appearance
and/or function from the ancestral form
• These are body features that resemble one
another in form or patterning due to descent
through common ancestors
• Example: Forelimbs bones in birds and bats
Morphological Convergence
• Also known as adaptive radiation
• Is the adoption of similar function over
periods of time in animals of evolutionary
remote lineages
• Analogous body parts perform similar
functions in dissimilar and distantly related
species
• Example: Sharks, penguins, and dolphins
(having similar function but not in the
structure in their forelimbs
Developmental Program of Larkspurs
• The common larkspur has a ringlike array of
petals to guide honeybees to the nectar, plus
the bulging reproductive structure for the bee
to hold on to.
• More recently evolved larkspur has tight
flowers that discourage bees but are attractive
to hummingbirds
Developmental Program of
Vertebrates
• Different organisms may show similarities in
morphology during their embryonic stages
that often indicate evolutionary relationship
– The early embryos of vertebrates strongly
resemble one another because they have
inherited the same ancient plan for development
– Some of the variation seen in adult vertebrates is
due to mutations in genes that control the rates of
growth of different body parts
Comparative Biochemistry
• Protein Comparisons
– Because genes dictate the sequence of amino
acids in proteins, analysis of proteins can
determine the similarity of genes between species
• Nucleic Acid Comparisons
– The degree of similarity of nucleotide sequence of
DNA reveals information about evolutionary
relationships
Continue…
• Molecular Clock
– Neutral mutations have no more measurable
effect on survival and reproductions rates than do
other alleles for the trait
– These mutations accumulate in the DNA can can
be used as a “molecular clock” for dating times of
divergence of species
Identifying, Naming, and Classifying
Species
• Taxonomy- is the field of biology that attempts to
identify, name, and classify organisms.
• Binomial nomenclature system
– Carl von Linnaeus – scientist to develop the naming
system
– Rules:
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Use the Genus and Species
Genus: First letter Capital letter
Species: Lower case letter
Written in italics
Language: Latin
Example Homo sapiens
Classification Schemes
• Organized ways of retrieving information
about particular species
• A hierarchical system (Largest (least related) to
smallest (more related)
– KingdomPhylumClassOrderFamily
GenusSpecies
– Traditional Classification has been modified to
reflect phylogeny –the evolutionary relationships
among species
Classification Taxonomy
• Classification schemes and evolutionary tree
diagrams are constructed to reflect the
perceived degree of morphological
divergences among major lineages
Cladistic Taxonomy
• Groups are arranged by branch points in an
evolutionary tree diagram
– Only species that shared derived traits– novel
features that evolved only once and is shared only
by descendants of the ancestral species in which it
evolved – are grouped past a given branch point,
which represents the last shared common
ancestor.
Continue…
– Diagrams called cladograms, do not convey direct
information about ancestors and descendants, but
rather, portray relative relationships by placing
taxa closer togetherr that share a more recent
common ancestor.
Classification System
• Robert Whittaker developed the original fivekingdom systems
• Today we use a six-kingdom system
Kingdom Monera
• Single celled prokaryotes (bacteria)
• Display great biochemical diversity but little
internal complexity
• Producers and decomposers
• Today, it has been divided into kingdoms
(Archaebacteria (bacteria that lives in harsh
environments (volcanoes))and
Eubacteria(normal bacteria))
Kingdom Protista
• Mostly single-celled eukaryotes
• Photoautotrophs (algae) and heterotrophs
(protozoas)
• More internal complexity than bacteria
• Very difficult to classify because this kingdom
has organisms that are plantlike or animallike
Kingdom Fungi
• Multicelled eukaryotes that feed by
extracellular digestion and absorption
• Hetertrophs include decomposers
• Many are pathogens and parasites
Kingdom Plantae
• Multicelled photosynthetic autotrophs
• Producers
• Form from embryos
Kingdom Animalia
• Diverse multicelled hetertrophs
• Range from sponges to vertebrates
Domains
• The domains are a largest hierarchical system
than Kingdoms
– Divided into three domains
– Eubacteria (normal bacteria), Archae (bacteria
that lives in harsh environments), and Eukarya
(organisms that have nucleus)
• Darwin saw evolution of one kind into another
as happening gradually, in small increments,
over hundreds or thousands of generations
• 1861 Fossil evidence of Archaeopteryx was
unearthed
– These organisms shows a transition from reptiles
and birds
– Like birds, it was covered with feathers, but like
reptiles, it had teeth and long, bony tail