1. Extinction. End of the line for a species
Extinction. End of the line for a species. Mass extinctions are catastrophic events in which major groups are lost abruptly and simultaneously.
Genetic disconnect
Basis of life’s diversity, as brought about by adaptive shifts, branchings, and radiations. Rates and times of change varied within and between lineages.
Genetic divergence
Basis of the unity of life. The biochemical and molecular basis of inheritance extends from the origin of first cells through all subsequent lines of descent.
Genetic persistence
Macroevolutionary Processes
Preserves or erodes species cohesion, depending on environmental pressures
Natural selection
Erodes species cohesion
Genetic drift
Preserves species cohesion
Gene flow
Stability or change in a species is the outcome of balances or imbalances among all of these processes, the effects of which are influenced by population size and by the prevailing environmental conditions.
Original source of alleles
Mutation
Microevolutionary Processes
Table 13.1  Summary of Processes and Patterns of Evolution
Table 13.1 Page 218

2. Speciation
Species- Individuals capable of successful interbreeding and producing fertile offspring.
Speciation: process by which new species come into being
Genetic divergence of reproductively isolated populations

3. Simplified diagram of genetic divergence
time A
time B
time C
time D
daughter species
parent species
time

6. Reproductive Isolating Mechanisms
Prezygotic Isolation
Ecological
Temporal
Behavioral
Gametic Mortality
Postzygotic Isolation
Zygotic Mortality
Hybrid Inviability
Hybrid Infertility

7. They interbreed anyway.
Different species!
Temporal isolation
Mechanical isolation
Behavioral isolation
Ecological isolation
They interbreed anyway.
Gamete mortality
Zygotes form, but...
Hybrid inviability
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Hybrid sterility
No offspring or weak offspring that die before reproducing

9. Types of Speciation
Sympatric Speciation- Isolation within a population
New species arises in the midst of the original population.
Ex: Lake Victoria Cichlids
Allopatric Speciation- Geographical isolation
Thought to be most common means of speciation
A geographic barrier, such as a river or a mountain range, causes the splitting of a population such that individuals of these now-separate populations can no longer interbreed.
Ex: Grey Squirrels around the Grand Canyon
Pioneering individuals may colonize a new habitat, such as an oceanic island.
Ex: Hawaiian Honeycreeper

10. Do not post to Internet The shared ancestor of all
of Hawaii’s honeycreepers
probably looked like this
house finch (Carprodacus)
Akepa
(Loxops coccineus)
Akekee
(L. caeruleirostris)
Nihoa finch
(Telespyza ultima)
Palila
(Loxioides bailleui)
Maui parrotbill
(Pseudonestor xanthrophrys)
Alauahio
(Paroreomyza montana)
Kauai Amakihi
(Hemignathus kauaiensis)
Akiapolaau
(H. munroi)
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to Internet
Akohekohe
(Palmeria doli)
Apap
(Himatione sanguinea)
liwi
(Vestiaria coccinea)

12. 1 2 3 4
A few individuals of a species on the mainland reach isolated island 1. Speciation follows genetic divergence in a new habitat. 1 2
Later in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence. 1 2 3 4
Speciation may also follow colonization of islands 3 and 4. And it may follow invasion of island by genetically different descendants
of the ancestral species.

13. Patterns of Speciation
Phylogeny- The evolutionary relationships among living, or extinct, organisms.
Evolutionary Trees- Summarize information about the continuity of relationships among species; summarize phylogenies
Branching in the tree represents speciation.
Angling of a branch represents gradual change in a lineage= phyletic evolution.
A straight line represents no change in a lineage.
Branches ending before the present represents extinction.
Adaptive radiation- Burst of divergence (branches) from a single lineage.

14. Patterns of Speciation

15. species 2
species 3
species 1
suspected branching
a single
lineage;
ancestral
stock
branch point (time of
genetic divergence,
speciation under way)

17. Kingdom
Genus
Species
Family
Order
Class
Phylum
Plantae
Plantae
Animalia
Musca
M. domestica
Muscidae
Diptera
Insecta
Anthropoda
Animalia
Homo
H. sapiens
Hominidae
Primates
Mammalia
Chordata
Coniferophyta
Anthophyta
Coniferopsida
Monocotyledonae
Coniferales
Asparagales
Cupressaceae
Orchidaceae
Juniperus
Vanilla
J. occidentalis
V. planifolia
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18. ‘Woodpecker’

19. ‘Woodpecker’

20. Eubacteria
Archaebacteria
Protista
Fungi
Plantae
Animalia

21. ANIMALS
PLANTS
arthropods
conifers
FUNGI
chordates
flowering plants
annelids
roundworms
echinoderms
ginkgos
sac
club
mollusks
fungi
fungi
cycads
horsetails
rotifers
zygospore-
ferns
forming
flatworms
fungi
lycophytes
cnidarians
bryophytes
chlorophytes
sponges
chytrids
green algae
amoeboid
PROTISTANS
protozoans
(stramenopiles)
(alveolates)
brown algae
red
ciliates
algae
chrysophytes
sporozoans
oomycotes ?
dinoflagellates
crown of eukaryotes
(rapid divergences)
euglenoids
slime molds
kinetoplastids
parabasalids
(e.g., Trichomonas)
EUBACTERIA
diplomonads
spirochetes
ARCHAEBACTERIA
(e.g., Giardia)
extreme
Gram-positive bacteria
chlamydias
methanogens
halophiles
cyanobacteria
proteobacteria
extreme
thermophiles
molecular origin of life

22. Cladistics
Cladistics- Classification based solely on evolutionary relationships.
Classification of organisms matches their evolutionary history and expresses the history in branching trees known as cladogram.
Clade-The entire portion of a phylogeny that is descended form common ancestor.

23. How do we construct evolutionary trees using cladistics?
Identify ancestral and derived traits.
Ancestral traits- Traits shared with a common ancestor
Most mammals have four limbs, having inherited this from common ancestor.
Derived traits- A trait that differs from the ancestral trait in a lineage.
Homologous Traits- Traits derived from a common ancestor.
Most mammalian limbs terminate in five digits, but in the hooved animals, there is only one. This trait, having only one digit, is a homologous trait and could be used to group all the hooved animals together.

24. early reptile pterosaur chicken bat porpoise penguin human 1 2 3 4 5 1

25. Archeaopteryx vs. Pigeon

26. Difficulties in determining homologous traits
Not all resemblances are products of common ancestry.
Homoplasy- Some traits are the product of convergent evolution, the evolution of the same trait in different lineages
Ex: Australian mammals vs. N. American Mammals

27. Homoplasy

28. Species that share a common ancestor should share many homologous traits
Therefore, if two species share the same trait, systematists should, until proven otherwise, assume that the trait is homologous, i.e. none of the traits are the product of convergent evolution.

29. shark
mammal
crocodile
bird
fur
feathers
gizzard
lungs
heart

30. Clades

31. Major Lineages

32. Constructing a Cladogram
Assumptions
Evolution of traits is irreversible, i.e. an ancestral trait can change into a derived one, but not the reverse.
Each trait can change only once in a lineage.

33. Constructing a Cladogram
Determine an outgroup, a taxon that is closely related to the group whose phylogeny is being constructed, but that branched off from the lineage of the group below its base on the evolutionary tree.
You know it’s different from the rest. It’s the one that’s “not like the others”.
Select traits that are believed to be homologous.
For each taxon, determine whether it has, or is lacking, that trait.
(+) indicates the presence of the trait in that taxon.
( - )indicates the lack of the trait in that taxon.
Taxa with more homologous traits, have a more recent common ancestor, i.e. they are farther up the tree

34. CENOZOIC MEZOZOIC ancestral mammal elephants, proboscideans
platypus, monotremes
kangaroos, marsupials
Insectivores, bats
shrews, other
whales, dolphins
horses, other
perissodactyls
deer, other
artiodactyls
manatees
anteaters
armadillos
carnivores
primates
rodents
rabbits
CENOZOIC
MEZOZOIC
ancestral mammal