lecture 2 : evolutionary patterns, rates and trends
DESCRIPTION
TRANSCRIPT
![Page 1: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/1.jpg)
ORIGIN OF LIFE
![Page 2: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/2.jpg)
![Page 3: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/3.jpg)
Key ConceptsEvidence of Evolution
- comes from biogeography, fossils and comparisons of body form, development and biochemistry among major groups.
![Page 4: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/4.jpg)
Macroevolutionary EventsAsteroid impacts, changing climates and
other global events contributed to the mass extinctions and recoveries, as well as emergence of new species.
![Page 5: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/5.jpg)
Organization of EvidenceNaming and classifying species helps us to
manage data on biodiversity.Cladistics is an evolutionary classification
system that groups species with respect to derived traits that evolved only once, in their last shared ancestor.
![Page 6: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/6.jpg)
Evidence from biogeography• Theory of uniformity prevailed when the
geologists map out vertical stacks of sedimentary rock.
• Recurring geologic events and others had changed the Earth irreversibly.
• `Jigsaw puzzle’ of Africa with the Atlantic coasts of South America?
• Were all continents once part of a bigger one that had splits into fragments and drifted apart?
![Page 7: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/7.jpg)
Evidence from biogeographyFindings as put continential drift into a
broader explanation of Earth’s crustal movements, the plate tectonics theory.
A big connection huge land on collision courses. Masses converged to form supercontinents that split forming new ocean basins Gondwana drifted south from the tropics until crunched into other land masses.
![Page 8: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/8.jpg)
Continental DriftContinents were once joined and have since
“drifted” apartInitially based on shapes Later supported by world distribution of
fossils and existing species, orientation of particles in iron-rich rocks
![Page 9: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/9.jpg)
Plate TectonicsEarth’s crust is fractured into plates
![Page 10: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/10.jpg)
island arc oceanic crust oceanic ridge trench continental crust
subducting plate
athenosphere(plastic layer of mantle)
hot spot
lithosphere(solid layer of mantle)
Fig. 13-6a, p.199
Plate Tectonics• Movement of plates is driven by upwelling of molten rock at mid-oceanic ridges
![Page 11: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/11.jpg)
Evidence from biogeography• The new supercontinent, Pangea extended
from pole to pole. With erosive forces of water and wind resculpted the land.
• Asteroid and meteorites hit the crust which left impacts and long term effect on the global temperature and climate.
• Such changes on land and in the ocean and at atmosphere influenced life’s evolution which took off in a new direction.
![Page 12: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/12.jpg)
Asteroid ImpactsMany past catastrophic
impacts altered the course of evolution
Iridium layer implicates asteroid in extinction of dinosaurs
Asteroids are still a threat
![Page 13: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/13.jpg)
10 mya65 mya260 mya420 mya
where ( seed fern) and Lystrosaurus (a tusked herbivore) evolved
420 mya – early supercontinent Gondwana
260 mya- collisionof land massesForming Pangea
65 mya – Pangea split apart and fragments drifted apart
10 mya – the present position
![Page 14: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/14.jpg)
Life in Pangea 260 myaGlossopteris (Seed fern)Lystrosaurus (a
Therapsidtusked herbivore) evolved
![Page 15: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/15.jpg)
Evidence from FossilsPhysical evidence of organisms that lived in
the distant past.Stratified layers of sedimentary rock are rich
in fossils are historical record of life.The deepest layers generally contain the
oldest fossils.
![Page 16: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/16.jpg)
FossilsRecognizable evidence
of ancient life
![Page 17: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/17.jpg)
What do Fossils Tell Us?Each species is a mosaic of ancestral and
novel traitsAll species that ever evolved are related to
one another by way of descent
![Page 18: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/18.jpg)
StratificationFossils are found in sedimentary rockThis type of rock is formed
in layersIn general, layers closest to the top
were formed most recently
![Page 19: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/19.jpg)
Sedimentary Rock
![Page 20: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/20.jpg)
Record Is IncompleteFossils have been found for about 250,000 speciesMost species weren’t preservedRecord is biased toward the most accessible regionsEven so, the fossil records is substantial enough to
reconstruct patterns and trends in the history of life.
![Page 21: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/21.jpg)
Dating Pieces of the Puzzle• How do we assign fossils to a place of time?• How do we know how old they really are?• By using the radiometric dating, this is
possible.• Understand the nature of radioisotope decay.• A radioisotope is an atom of an element with
an unstable nucleus which decays spontaneously until the atom becomes a more stable element.
![Page 22: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/22.jpg)
Radiometric Dating• The proportions of the radioisotope to its
daughter elements in a sample can be used to calculate the sample’s age.
• This applies when the rate of decay for each isotope is constant.
• A predictable number of a radioisotope’s atoms in any sample will decay in a characteristic time span.
• No change in pressure, temperature or chemical state alters that rate.
![Page 23: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/23.jpg)
Radiometric Dating• Can be used to reveal the age of rocks.• E.g. with uranium 238-to-lead ratio in the
oldest rocks, geologists predicted that the Earth formed more than 4.6 billion years ago.
• Dating the sedimentary rock yield s the date its component materials formed but not the date they actually sedimented.
• The only way to date the old fossils is to find their position relative to the rocks.
![Page 24: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/24.jpg)
Radiometric datingFossils that retain some
carbon can be dated directly by measuring their ratio of 12C to 14C.
Trace amounts of 14C were incorporated in the tissues of a living mollusk.
As long the mollusk was living, the proportion of 14C to 12C remained the same in the tissue.
![Page 25: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/25.jpg)
Radiometric datingWhen mollusk died, it
stopped gaining carbon.
Over time, the proportion of 14C to 12C in its remain fell due to the radioactive decay of the 14C.
Half of the 14C had decayed in 5,370 years.
![Page 26: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/26.jpg)
Radiometric datingWhen such fossil is found
and measured of its 14C to 12C ratio to determine the half-life reductions since death.
The ratio turns out to be one eighth of the 14C to 12C ratio in living organisms.
Thus, the mollusk lived about 16,000 years ago.
![Page 27: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/27.jpg)
Radiometric DatingOrganism becomes buried in ash or
sedimentsOrganic remains become infused
with metal and mineral ionsCarbon 14 dating
![Page 28: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/28.jpg)
Radiometric Dating
after two half-lives
after one half-life
parent isotope innewly formed rock
![Page 29: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/29.jpg)
The decay if radioisotopes at a fixed rate to more stable forms.
The half –life of each kind of radioisotope is the time it takes for 50% of a sample to decay.
After two half-lives, 75% of the sample has decayed , and so on.
![Page 30: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/30.jpg)
Geologic Time Scale
Boundaries based on transitions in fossil record
Cambrian period
Proterozoic eon2,500
myaArchean eon and earlier
Ordovician period
Silurian periodDevonian period
544
505
440
410
Carboniferous period
Permian period
Cretaceous period
Tertiary periodQuaternary period
360
286
248
213
145
65
Cambrian period
Jurassic periodTriassic period
Paleozoic era
Mesozoic era
Cenozoic eraPhanerozoic eon
![Page 31: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/31.jpg)
MacroevolutionMajor patterns and trends among lineagesRates of change in geologic time
![Page 32: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/32.jpg)
5:28:41 A.M.,origin of eukaryotes
2:05:13 A.M.origin of prokaryotes
11:59:59 A.M., first humans
11:44:30 A.M., dinosaurs, flowering plants
Earth’s crust solidifies
Fig. 13-5, p.198
11:21:10 A.M., origin of mammals
10:51:7 A.M., early fishes
Macroevolution
![Page 33: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/33.jpg)
Evidence from Comparative MorphologyEvolution mans heritable changes in lines of
descent.Comparisons of body form and structures of
major groups of organisms yield clues for the evolutionary relationships.
Comparative morphology is study of body forms and structures of major groups of organisms.
![Page 34: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/34.jpg)
Comparative MorphologyEvidence of a common ancestor maybe due
to the similarities in the internal structure of one or more body parts.
Similar body parts which reflect shared ancestry are homologous structures.
used differently in different groups, but same genes direct their development.
![Page 35: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/35.jpg)
Morphological DivergencePopulation of a species diverge genetically
after gene flow ends between them.Over time, some of the traits that define the
species also diverge.Change from body form of a common
ancestor is a macroevolutionary pattern.
![Page 36: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/36.jpg)
Morphological Divergence
Change from body form of a common ancestor
Produces homologous structures
1
1
1
1
1
1
2
2
2
2
2
2
2
3
3
3
3
3
3
3
4
4
4
4
4
5
5
5
5
early reptile
pterosaur
chicken
bat
porpoise
penguin
human
![Page 37: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/37.jpg)
Morphological ConvergenceSimilar body parts are not always homologous
and may have evolved independently in separate lineages as adaptations to the same environmental pressures.
Such parts are named as analogous structures which look alike in different lineages but did not evolve in a shared ancestor.
Evolved independently after lineages diverged.
Evolution of similar body parts in different lineages is called morphological convergence.
![Page 38: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/38.jpg)
Morphological Convergence
![Page 39: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/39.jpg)
body wall (exoskeleton)
strong membrane (extension of wall)
wing veins
Fig. 13-9c2, p.202
Morphological Convergence
![Page 40: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/40.jpg)
Limbs with 5 digits
wings
birdscrocodilesHumansbatsInsects
wings
wings
The evolutionary tree diagram shows that wings evolvedindependently in three separate lineages that bled to bats,birds and insects.
![Page 41: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/41.jpg)
Key conceptsWith morphological divergence, a body
inherited from a common ancestor becomes modified differently in different lines of ancestor. Such parts are homologous structures.
With mophological convergence, body parts appear alike evolved independently in different lineages, not in a common ancestor. Such parts are analogous structures.
![Page 42: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/42.jpg)
Changes in patterns in developmentComparing the patterns of embryonic
development often yields evidence of evolutionary relationships
Similarities in patterns of development are often clues to shared ancestry.
Mutation in master genes are capable of launching body plans in new evolutionary directions. Changes in these and other genes that affect development may result in structural differences among related lineages.
![Page 43: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/43.jpg)
Genes and variationHomoetic genes guide formation of specific
body parts during embryonic development.A mutation in one homoetic hgene can
disrupt the body’s form.Consequences, may be severe or maybe
advantageous.e.g. formation of flowers.
![Page 44: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/44.jpg)
Genes and VariationHow many legs?Impact of mutations on animal evolution.Embryos of many vertebrate species develop
in similar ways.Heritable changes in the onset, rate or
completion of early steps in development occur.
![Page 45: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/45.jpg)
How many legs? Mutations in master
genes may explain why animals differ in the number of appendages.
Dlx, a homoetic gene makes limbs from wherever is expressed.
Fossil animal unrestricted expression of Dlx gene in Cambrian times.
![Page 46: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/46.jpg)
Variations in control over Dlx expression, showed by green fluorescence in embryonic appendages of
velvet walking worm
Blue dye in mouse embryo’s foot
![Page 47: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/47.jpg)
Chimps and HumansGene duplications may account for some
major functional differences among species that have nearly identical genes.
Last shared ancestor of chimpanzees and humans lived between 6-4 mya.
Not more than 98% of human DNA is identical with chimp DNA.
What accounts for the morphological and behavioral differences between the two ?
![Page 48: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/48.jpg)
Skull bones : bones of face and brain chamber in humans increase in size at same rate from infant to adult while facial bones in chimps grow faster than the brain chamber humans and chimps have different faces.
![Page 49: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/49.jpg)
Proportional Changes in Skull
chimpanzee
human
![Page 50: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/50.jpg)
Molecular EvidenceBiochemical traits shared by species
show how closely they are relatedCan compare DNA, RNA, or proteins
![Page 51: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/51.jpg)
Clues in DNA, RNA and ProteinsAll species have a mixture of ancestral and
novel traits, including biochemical ones.The kind and number of traits that species
share are clues to evolutionary relationships.Biochemical similarity is greatest among the
most closely related species and smallest among the most remote.
![Page 52: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/52.jpg)
Comparing ProteinsCompare amino acid sequence of proteins
produced by the same gene Human cytochrome c (a protein)
Identical amino acids in chimpanzee proteinChicken protein differs by 18 amino acidsYeast protein differs by 56
![Page 53: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/53.jpg)
raccoon
red panda
giant panda
spectacled bear
sloth bear
sun bear
Asiaticblack bear
American black bear
brown bear
polar bear
An example of how biochemical comparisons can assist in constructing and refining the evolutionary trees.Red pandas, giant pandas and brown bears was constructed using sequence Comparisons of mitochondrial and nuclear DNA. Findings indicated that red pandamaybe more closely related to skunks, weasels and otter rather than to raccoons.
![Page 54: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/54.jpg)
Sequence ConservationCytochrome c functions in electron
transport in cells.Deficits in this vital protein would be lethalLong sequences are identical in wheat,
yeast, and a primate indicating the a.a. sequences has been highly conserved even in these three evolutionary distant lineages.
![Page 55: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/55.jpg)
yeastwheatprimate
Yeast (top row)Wheat (middle)Primate (bottom)
Amino acids are identical
![Page 56: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/56.jpg)
Nucleic Acid ComparisonUse single-stranded DNA or RNAHybrid molecules are created,
then heatedThe more heat required to break hybrid,
the more closely related the species
![Page 57: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/57.jpg)
Molecular ClockAssumption: “Ticks” (neutral
mutations) accumulation in the DNA at a constant rate .
Count the number of differences in the DNA base sequences or a.a. sequences to estimate time of divergence among species or groups of them.
![Page 58: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/58.jpg)
grown in watergrown on land
Differences in form between two plants of the same speciesSaggitaria sagittifolia. The leaf shapes are responses to different conditions in the environment, not the differences in the genes
![Page 59: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/59.jpg)
Reproductive Isolation
Cornerstone of the biological species conceptSpeciation is the attainment of reproductive
isolationReproductive isolation arises as a by-product
of genetic change
![Page 60: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/60.jpg)
Biological Species Concept “Species are groups of interbreeding natural
populations that are reproductively isolated from other such groups.”Ernst Mayr , evolutionary biologist
In other words,Species as one or more groups of individuals that potentially can interbreed, produce fertile offspring and do not interbreed with other groups.
![Page 61: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/61.jpg)
Reproductive IsolationIn nature, sexually reproducing species
attain and maintain separate identities by reproductive isolation ---the end of gene exchanges between populations.
New species arise by the evolutionary process of speciation.
This begins as gene flow ends between populations which diverge genetically as mutation, genetic drift and natural selection operate in each one independently.
![Page 62: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/62.jpg)
Genetic DivergenceGradual accumulation of differences in the
gene pools of populationsNatural selection, genetic drift, and mutation
can contribute to divergenceGene flow counters divergence
![Page 63: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/63.jpg)
Genetic Divergence
time A time B time C time D
daughter species
parent species
![Page 64: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/64.jpg)
Reproductive isolating mechanismsSpeciation occur after a very long period of
divergence, or after one generation.As two populations diverge, reproductive
isolation mechanisms arise.Such mechanisms are heritable aspects of
body form, function or behavior that prevent interbreeding between different species and they reinforce differences between diverging populations.
![Page 65: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/65.jpg)
Reproductive Isolating Mechanisms
Prevent pollination or mating
Block fertilization or embryonic
development
Cause offspring to be weak or sterile
![Page 66: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/66.jpg)
Reproductive IsolationMechanisms
![Page 67: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/67.jpg)
Prezygotic Isolation MechanismMechanical isolation
Temporal isolation
Behavioral isolation
Ecological isolation
Gamete incompatibility /mortality
![Page 68: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/68.jpg)
Mechanical IsolationWasp and zebra orchid.The plant release some
chemicals that attract the insect which mistook the flower as the female.
![Page 69: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/69.jpg)
Temporal isolation among cicadas
Reproductive Isolation
![Page 70: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/70.jpg)
Temporal Isolation
CicadaTiming of
reproduction differs between 3 species.
If interbreeding occurs, it will take them to get together once every 221 years.
![Page 71: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/71.jpg)
Behavioral IsolationBehavioral differences stop gene flow
between related species.Males and females engage in courtship
displays before sex.Female albatross recognizes the singing,
wing spreading or head bobbing of a male of her species as an overture to sex.
Female of different species ignore this behavior.
![Page 72: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/72.jpg)
Behavioral IsolationAlbatrosses
![Page 73: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/73.jpg)
Ecological SpeciationOccurs to two populations in different
microenvironments .Manzanita species at foothills of Sierra
Nevada: one at 600-1850m and the other at 750-3350m. They hybridize rarely. Both conserve water but one is adapted to less intense water stress while the other species lives in drier hillsides.
Thus, cross pollination is unlikely to happen.
![Page 74: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/74.jpg)
Gamete IncompatibilityIf and whenever different species interbreed
anyway, reproductive isolating mechanism does happen.
Reproductive cells of different species have molecular incompatibilities, so fertilization does not occur.
![Page 75: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/75.jpg)
If whenever zygote form,but…Postzygotic isolating mechanisms take place.Two consequences happen:(1)Hybrid inviability : Hybrid embryos die early
or the new individuals die before they can reproduce
(2)Hybrid sterility : Hybrid individuals cannot make functional gametes
Thus, no offspring, sterile offspring, weak offspring die before reproducing.
![Page 76: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/76.jpg)
Postzygotic Isolating Mechanisms
Early death
Sterility or sterile F2
offspring
Low survival rates
![Page 77: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/77.jpg)
Llama-Camel Hybrid
![Page 78: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/78.jpg)
Models for Speciation
Allopatric speciation
Sympatric speciation
Parapatric speciation
![Page 79: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/79.jpg)
Allopatric SpeciationSpeciation in geographically isolated
populations Some sort of barrier arises and prevents
gene flowEffectiveness of barrier varies with speciesGene flow ends, and genetic divergence
give rise to daughter species.
![Page 80: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/80.jpg)
Allopatric Speciationilamas
camels
vicunas
Connection of land bridge between twocontinents
![Page 81: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/81.jpg)
Extensive Divergence Prevents Inbreeding
Species separated by geographic barriers will diverge genetically
If divergence is great enough it will prevent inbreeding even if the barrier later disappears
![Page 82: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/82.jpg)
ArchipelagosIsland chains some distance from continents
Galapagos IslandsHawaiian Islands
Colonization of islands followed by genetic divergence sets the stage for speciation
![Page 83: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/83.jpg)
1
23
4
1
23
4
1
2
A few individuals of a species on the mainland reach isolated island 1. Speciation follows genetic divergence in a new habitat.
Later in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence.
Speciation may also follow colonization of islands 3 and 4. And it may follow invasion of island 1 by genetically different descendents of the ancestral species.
3
4
![Page 84: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/84.jpg)
Hawaiian IslandsVolcanic origins,
variety of habitats Adaptive radiations:
Honeycreepers: in absence of other bird species, they radiated to fillnumerous niches Housefinch (Carpodacus)
Ancestral type
![Page 85: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/85.jpg)
Akepa (Loxops coccineus)Fig. 13-18d1, p.209
Speciation in Hawaiian Honeycreepers
![Page 86: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/86.jpg)
Hawaiian honeycreepers
An example of a burst of speciations on an isolated archipelago.
These species are adapted to diverse food sources, such as insects, seeds, fruits and floral nectar.
![Page 87: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/87.jpg)
Speciation without a BarrierSympatric speciation
Species forms within the home range of the parent species
Parapatric speciationNeighboring populations become distinct
species while maintaining contact along a common border
![Page 88: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/88.jpg)
Sympatric SpeciationDaughter species arise from a population even
in the absence of a physical barrier.Polyploidy – speciation occur in an instant with
a change in the chromosome number where- duplication of somatic cells do not divide during mitosis or- nondisjunction in meiosis resulting gametes with unreduced chromosome number
![Page 89: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/89.jpg)
Speciation by PolyploidyChange in chromosome number
(3n, 4n, etc.)Offspring with altered chromosome number
cannot breed with parent populationCommon mechanism of speciation in
flowering plants
![Page 90: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/90.jpg)
Figure 18.9Page 299
Possible Evolution of WheatTriticum monococcum (einkorn)
T. aestivum (one of the common bread wheats)
Unknown species of wild wheat
T. turgidum(wild emmer)
T. tauschii (a wild relative)
42AABBDD14AA 14BB 14AB 28AABB 14DDXX
cross-fertilization, followed by a spontaneous chromosome doubling
![Page 91: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/91.jpg)
Sympatric speciation in wheat
Possible Evolution of Wheat
![Page 92: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/92.jpg)
Sympatric Speciation in African Cichlids
Studied fish species in two lakesSpecies in each lake are most likely
descended from single ancestorNo barriers within either lake
![Page 93: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/93.jpg)
Sympatric Speciation in African CichlidsFeeding preferences localize species in
different parts of lake
![Page 94: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/94.jpg)
Parapatric SpeciationOccurs when one population extends across a
broad region encompassing diverse habitats.Different habitats exert distinct selection
pressures on parts of population and maybe divergences leading towards speciation.
Hybrids form in between are less fit than individuals on either side of it.
Population maintaining contact along common border evolve into distinct species.
![Page 95: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/95.jpg)
Parapatric SpeciationPopulations in contact along a common
border
giant velvet worm
blind velvet worm
![Page 96: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/96.jpg)
We’re All RelatedAll species are related by descent
Share genetic connections that extend back in time to the prototypical cell
![Page 97: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/97.jpg)
Gradual ModelSpecies emerge through many small
changes accumulating over time Fits well with evidence from certain
lineages in fossil recordFossilized shells from vertical
sequence of sedimentary rock layers.First shell (bottom) – 64.5 mil yrs oldMost recent (top) – 68 mil yrs oldThis analysis confirms the
evolutionary order matches their geological sequence.
![Page 98: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/98.jpg)
Punctuation ModelSpeciation model in which most changes in
morphology are compressed into brief period near onset of divergence
Supported by fossil evidence in some lineages
![Page 99: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/99.jpg)
Adaptive RadiationBurst of divergence Single lineage gives rise to many
new speciesNew species fill vacant adaptive
zone Adaptive zone is “way of life”Cenozoic radiation of mammals
![Page 100: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/100.jpg)
Adaptive Radiations of Mammals
![Page 101: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/101.jpg)
CoevolutionProcess that close ecological interactions
among species that cause them to evolve jointly.
Each species adapts to changes in the other; over time the two may become interdependent.
Some coevolved species no longer survive without one another.
Predator-prey ; host-parasite; flower-pollinator
![Page 102: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/102.jpg)
ExtinctionIrrevocable loss of a speciesMass extinctions play a major
role in evolutionary historyFossil record shows 20 or more
large-scale extinctionsReduced diversity is followed by
adaptive radiation
![Page 103: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/103.jpg)
Who Survives?Species survival is somewhat randomAsteroids have repeatedly struck Earth,
destroying many lineagesChanges in global temperature favor lineages
that are widely distributed
![Page 104: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/104.jpg)
Evolutionary TheoryInvolves processes of both macroevolution
and microevolution.All come to explain the same thing--- the tree
of life that connects all species by ancestry.
![Page 105: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/105.jpg)
MicroevolutionInvolves processes:- Natural selection preserves or erodes species
cohesion depending on environmental pressures- Mutation original source of alleles- Gene flow preserves species of cohesion- Gene drifterodes species of cohesionStability or change in a species is the outcome of
balances / imbalances among all of the above processes. The effects are influenced by population size and the prevailing environmental conditions.
![Page 106: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/106.jpg)
MacroevolutionDescribe genetic changes within a species or
population.Is our name for large-scale pattern such as one
species giving rise to several others, the origin of major groups, and major extinction events.
Involves:- Genetic persistence basis of unity of life
(biochemical and molecular basis of inheritance)- Genetic divergence basis of life’s diversity (adaptive
radiation, branching with rates and times of change)- Genetic disconnect extinction (end of line of the
species brought by catastrophic events)
![Page 107: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/107.jpg)
Organizing information about speciesConnections among species, from ancient to
recent, are evidence of evolution.Species are put into groups based on what we
know about their evolutionary relationships.Taxonomy is a set of rules of naming organisms
and classifying them into series of ranks based on their traits.
e.g. every organism has a unique two-part scientific name. Genus-species. (Homo sapien)
![Page 108: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/108.jpg)
TaxonomyThe identification, naming, and
classification of speciesSomewhat subjectiveInformation about species can be
interpreted differently
![Page 109: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/109.jpg)
The higher taxaA taxon (plural, taxa) is an organism or group
of them.Categories above species are higher taxa.Each higher taxon consists of a group of the next lower taxon.
Lead to the classification system developed by a Swedish naturalist, Carolus Linnaeus (1707-1778), who separated animals and plants according to certain physical similarities and gave identifying names to each species.
Linnaeus’s system classified plants and animals on seven levels, using Latin and Greek words.
![Page 110: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/110.jpg)
Principles and importance of taxonomy
Taxonomy as of science of classificationImportant to find, identify, study, describe
and understand the distribution of organisms grouping/classify organisms according to
their shared common features (as of taxon)based on seven levels of taxon:
![Page 111: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/111.jpg)
Taxa (plural) Taxon (singular)KingdomPhylumClass OrderFamilyGenusSpecies
![Page 112: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/112.jpg)
Levels of taxonKingdom largest group sharing common features
Phylum Subdividision of kingdom; contain large number of organism that have one / two fundamental features
Class Group of orders within a phylum
Order Group of related families
Family Group of related genera
Genus Group of similar and closely-related species
Species Group of individuals which share a large number of features and capable of inbreeding to produce fertile offspring
![Page 113: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/113.jpg)
Take note!!Number of organisms
in each taxon decreases as we goes down the levels of taxon.
Number of shared characteristics increases as we go up the levels of taxon.
Kingdom
Phylum
Class
Order
Family
Genus
Species
![Page 114: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/114.jpg)
Classification of a single species of animal
![Page 115: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/115.jpg)
How a brown squirrel is classified: Kingdom (Animalia, or “animal”) Phylum (Chordata, or “has a backbone”) Class (Mammalia, or “has a backbone and nurses its young”)Order (Rodentia, or “has a backbone, nurses its young, and
has long, sharp front teeth)Family (Scuridae, or “has a backbone, nurses its young, has
long, sharp front teeth, and has a bushy tail) Genus (Tamiasciurus, or “has a backbone, nurses its young,
has long, sharp front teeth, has a bushy tail, and climbs trees) Species (hudsonicus, or “has a backbone, nurses its young,
has long, sharp front teeth, has a bushy tail, climbs trees and has brown fur on its back and white fur on its underparts)
It is not necessary to go through the entire seven-level classification system to identify a plant or animal.
Two names are sufficient—the genus and species names. Thus, the scientific name for the brown squirrel is
Tamiasciurus hudsonicus.
![Page 116: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/116.jpg)
Because two names are used, the system used by Linnaeus and based on Latin is known as the binomial (two names) system of nomenclature (naming).
The naming of species and other taxa follows a set of rules:
(1) International Code of Botanical Nomenclature (ICBN) for plants,
(2) International Code of Zoological Nomenclature (ICZN) for animals.
The name game
![Page 117: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/117.jpg)
Naming SpeciesEach species has a two-part nameFirst part is generic nameSecond part is species nameUrsus arctos = brown bear
Ursus americanus = black bearBufo americanus = American toad
![Page 118: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/118.jpg)
Rules of the gameConsistency in using the system of classification.The generic (genus) name is the first and always
given with capital letterThe specific (species) name comes second and
always starts with small letter.Both names should either be written in Italics or
underlinedScientific name should be written in full the first
time it is used. But after that, it can be abbreviated.
If the species is unknown, then the abbreviation `sp.’ can be used.
![Page 119: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/119.jpg)
Some general rules for nomenclature: All taxa must belong to a higher taxonomic group.
Often a newly discovered organism is the sole species in a single genus, within a single family...etc.
The first name to be validly and effectively published has priority. This rule has caused numerous name changes, especially with fossil organisms: Brontosaurus is invalid, and the correct name for the big sauropod dinosaur is Apatosaurus, Eohippus (the tiny "dawn horse") is invalid and should be referred to as Hyracotherium. Sometime, however, names can be conserved if a group of systematists agrees.
All taxa must have an author. When you see a scientific name such as Homo sapiens L, the L stands for Linnaeus, who first described and named that organism. Most scientists must have their names spelled out.
![Page 120: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/120.jpg)
Taxonomy of a selected plant species.
Note that the Kingdoms have a great deal more types of creatures in them than do species.
![Page 121: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/121.jpg)
The system is successful because :each particular organism has its own unique scientific name
can see that two species are closely related based on similar/same genus.
![Page 122: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/122.jpg)
Examples of Classification
Kingdom
GenusSpecies
FamilyOrderClassPhylum
Plantae
JuniperusJ. occidentalis
CupressaceaeCuoniferalesConiferopsida Coniferophyta
Plantae
VanillaV. planifolia
OrchidaceaeAsparagalesMonocotyledonaeAnthophyta
Animalia
MuscaM. domestica
MuscidaeDipteraInsectaAnthropoda
Animalia
HomoH. sapiens
HominidaePrimatesMammaliaChordata
western juniper vanilla orchid housefly human
![Page 123: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/123.jpg)
Taxonomic Classification
![Page 124: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/124.jpg)
Taxonomic Classification
![Page 125: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/125.jpg)
PhylogenyThe scientific study of evolutionary
relationships among speciesPractical applications
Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another
![Page 126: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/126.jpg)
Six-Kingdom ClassificationBacteria Archaea Protists Plants Fungi Animals
![Page 127: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/127.jpg)
Three-Domain SystemBacteria Archaea Eukarya
![Page 128: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/128.jpg)
Tree of Life
![Page 129: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/129.jpg)
Classification systems
Evolutionary tree for plants
![Page 130: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/130.jpg)
CladisticsCladistics is a set of methods by which we
can determine the evolutionary relationships and used in phylogenetics classification schemes.
Organisms are grouped by shared derived traits.
Monophyletic group - A group of species all descended from an ancestral species in which a particular derived trait first evolved.
![Page 131: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/131.jpg)
Patterns of Change in a LineageCladogenesis
Branching patternLineage splits, isolated populations diverge
AnagenesisNo branchingChanges occur within single lineageGene flow throughout process among its
populationIn time, species becomes so different from
its ancestor becomes a new species and the ancestral species extinct.
![Page 132: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/132.jpg)
Evolutionary Trees
ancestral stock
species 1
species 2 species 3
Summarize information about relationships among groups
branch point (time of genetic divergence,speciation under way)
suspected branching
![Page 133: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/133.jpg)
Evolutionary tree diagram
Evolutionary Trees
![Page 134: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/134.jpg)
Cladistic approachA clade is a group of species that share a
set of derived traits (those that do not appear in the most recent ancestor).
A clade may correspond to the Linnaean group but not every Linnaean group correspond to a clade.
With biochemistry approach and DNA sequencing methods, data used to define a clade can be updated frequently .
![Page 135: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/135.jpg)
A Cladogram
![Page 136: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/136.jpg)
Evolutionary Tree
Summarize our best understanding of the pattern of evolution for a group of organisms.
![Page 137: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/137.jpg)
Evolutionary Tree
![Page 138: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/138.jpg)
Current Evolutionary Tree
![Page 139: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/139.jpg)
How to construct a CladogramUsing a selection of traits among groups to
construct a simple cladogram, step by step approach.
Is an estimate of ‘who came from whom’Has no time bar with absolute dates.Reflect morphological and biochemical comparisonsHelp to visualize monophyletic groups as sets within
sets.Reference:
http://www.eeescience.utoledo.edu/Faculty/Dwyer/Biodiversity/ConstructingCladograms.htm
![Page 140: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/140.jpg)
Step 1Start with a list of taxa that are to be fit into
the cladogram (the ingroup) and their derived characters.
Choose an outgroup; a taxa that shares a primitive character with the ingroup, but exhibits none of the derived characters.
![Page 141: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/141.jpg)
![Page 142: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/142.jpg)
Step 2Fill in a character table that will be used to
make the cladogram. The taxon with the least number of derived characters should be the first row. The taxon with the greatest number of derived characters should be the last row.
The character that is seen in the greatest number of taxa should be the first column. The character that is exhibited in the least number of taxa should be the last column.
Use ones and zeroes to represent presence (1) or absence (0) of specific characters in specific species.
![Page 143: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/143.jpg)
![Page 144: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/144.jpg)
Make a Venn diagram to place the 8 animals in groups to illustrate those characteristics which different animals have in common.
chimphumanchimpanzee
Amphioxus : no back bone
Lamprey : has backboneSunfish : has jaws
Lizard : has amniotic egg
Bear: has mammary glands Newt : has four limbs
![Page 145: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/145.jpg)
Step 3Build the cladogram step-by-step. Start with
the first character (first column). The outgroup is the only taxon that doesn't
exhibit the first character. Separate it from the other taxa on the
cladogram. Remember that the outgroup shares a
common ancestor with the ingroup. Each split in the cladogram marks a separate
evolutionary event.
![Page 146: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/146.jpg)
![Page 147: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/147.jpg)
![Page 148: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/148.jpg)
![Page 149: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/149.jpg)
Step 4By looking at the completed cladogram, we
can see which species are most closely or distantly related.
In this example, humans are more closely related to chimpanzees, than to any other taxon on the cladogram.
![Page 150: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/150.jpg)
![Page 151: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/151.jpg)
Do the Bring Home Quiz provided in the next slide. You are to complete the assignment as during the next lecture, answers shall be given and marking shall be carried out at the same time.
Marked assignment must be hand over back to the instructor as marks shall be counted as part of the assessment.
Those did not bring in their assignment for the next lecture are considered FAIL (zero % is given).
![Page 152: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/152.jpg)
BRING HOME QUIZ (20 marks)Follow the instruction provided in the text
below.For the following animals, construct your own
cladogram (+ means that the animal has the given derived character trait) showing :
character table (3 marks) ;Venn diagram (7 marks) and completed cladogram (8 marks). *Make sure that you apply the steps as
outlined from the lecture.
![Page 153: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/153.jpg)
BRING HOME QUIZDerived Characters
segmented jaws hair placenta multicellular limbs
kangaroo + + + - + +earthworm + - - - + -amoeba - - - - - -lizard + + - - + +cat + + + + + +sponge - - - - + -salmon + + - - + -
![Page 154: Lecture 2 : Evolutionary Patterns, Rates And Trends](https://reader037.vdocuments.mx/reader037/viewer/2022110113/53ff91548d7f7261088b463c/html5/thumbnails/154.jpg)
Based on the completed cladogram that you have constructed, answer the following questions:
Which ingroup is most closely related to sponges?(1 mark)________________________________
Which ingroup is most distantly related to sponges?(1 mark) ________________________________
TOTAL : 20 marks