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Evolution . Evolution and the Theory of Natural Selection . What is Evolution?. The change in gene frequencies in a population over time. Why the controversy?. Intelligent Design vs Evolution. The Greek philosopher Aristotle (384-322 BCE)

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Evolution

Evolution

Evolution and the Theory of Natural Selection


What is evolution
What is Evolution?

The change in gene frequencies in a population over time




  • The Greek philosopher Aristotle (384-322 BCE)

    • Viewed species as fixed and unchanging (Scalanaturae) Fixed rungs on a ladder of complexity

  • The Old Testament of the Bible

    • Holds that species were individually designed by God and therefore perfect

  • CarolusLinnaeus (1707-1778)

    • Interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose

    • Was a founder of taxonomy, classifying life’s diversity “for the greater glory of God”


Charles darwin 1809 1882
Charles Darwin(1809-1882)

  • Born in England

  • Attended medical school, HATED IT, and dropped out to become a priest

  • Liked to stuff birds instead of dissect humans

  • Didn’t like grave robbing for bodies

  • Boarded the H.M.S. Beagle for a 5 year UNPAID journey as a naturalist (nothing exists outside of natural laws that govern earth)


Charles darwin
Charles Darwin

  • “Descent with modification” from an ancestral species

  • November 24th 1859


The Origin of Species

Occurrence of Evolution

Descent with Modification

all organisms related through descent from some unknown

ancestral population

diverse modifications (adaptations) accumulated over time

Mechanism of Evolution

Natural Selection and Adaptation

natural selection is the differential success in reproduction

natural selection occurs from the interaction between the

environment and the inherit variability in a population

variations in a population arise by chance

Can selection actually cause substantial change in a population?


Journey of the h m s beagle
Journey of the H.M.S. Beagle


  • Darwin’s Field Research

  • South American flora/fauna distinct from European flora/fauna

  • S. American temperate species were more closely related to S. American tropical species than European temperate species

  • S. American fossils were distinctly S. American

Tropical Rainforest of South America


  • Galapagos Islands

  • + most animal species on Galapagos unique to those islands, but

  • resemble S. American continental species

  • + Darwin’s Finches

  • - 13 types

  • + some unique to individual islands

  • + others found on two or more islands close together

  • Darwin proposed:

  • + new species could arise from an ancestral population by

  • gradually accumulating adaptations to a different environment.

  • - Theory of natural selection as the mechanism of adaptive

  • evolution


Alfred russel wallace 1823 1913
Alfred Russel Wallace(1823-1913)

Presented a paper with identical ideas as Darwin on July 1, 1858 at the Linnaean Society meeting

Was a botanist who came up with virtually the same concept of natural selection more or less independently through his studies on the Malay archipelago. Darwin panicked because he was not ready with his book yet!



Jean baptiste lamarck 1744 1829
Jean Baptiste Lamarck (1744-1829)

  • Lamarck claimed that evolution was driven by "use vs. disuse"

  • A used structure will become larger, stronger and more important.

  • A disused structure will atrophy and become VESTIGIAL.

  • Evolution occurs because organisms have an innate drive to become more complex


Theory of use vs disuse

The long necks of giraffes were due to their stretching for food, and giraffes passed their stretched necks on to their offspring.

Similarly, the big, “ripped” muscles developed by the village blacksmith with all his hammering and slinging of heavy metal objects would be expected to be passed on to his offspring.

Theory of “Use vs. Disuse”


Theory of acquired characteristics
Theory of “Acquired Characteristics” food, and giraffes passed their stretched necks on to their offspring.

  • Lamarck claimed that traits acquired during an organism's lifetime could be inherited by that organism's offspring.


Georges cuvier 1769 1832
Georges Cuvier food, and giraffes passed their stretched necks on to their offspring. (1769-1832)

  • Created Paleontology

    (The study of fossils)

  • He noted that deeper layers of sedimentary rock had diversity of organisms far different from present day life found in more recent layers

  • Proposed the idea of extinction based on fossils


James hutton 1726 1797
James Hutton food, and giraffes passed their stretched necks on to their offspring. (1726-1797)

  • A Scottish geologist who challenged Cuvier's view in 1795 with his idea of GRADUALISM

  • Proposed that large changes in the earth's surface could be caused by slow, constant processes

    e.g. erosion by a river


Charles lyell 1797 1875
Charles Lyell food, and giraffes passed their stretched necks on to their offspring. (1797-1875)

  • Earth processes had been going on constantly, and could explain the appearance of the earth.

  • This theory, uniformitarianism, was a strong basis for Darwin's later theory of natural selection.


Thomas malthus 1766 1834
Thomas Malthus food, and giraffes passed their stretched necks on to their offspring. (1766-1834)

  • Suggested that much of humanity's suffering (disease, famine, homelessness and war) was the inevitable result of overpopulation: humans reproduced more quickly than their food supply could support them.

  • Malthus showed that populations, if allowed to grow unchecked, increase at a geometric rate.


Darwin made some profound observations from which ernst mayr inferred some conclusions
Darwin made some profound observations, from which Ernst food, and giraffes passed their stretched necks on to their offspring. Mayr inferred some conclusions...

  • Observation #1. All species have huge potential fertility

  • Observation #2. Except for seasonal fluctuations, populations tend to maintain a stable size.

  • Observation #3. Environmental resources are limited.


Inference 1
Inference #1 food, and giraffes passed their stretched necks on to their offspring.

  • The production of more individuals than the environment can support leads to a "struggle for existence," with only a fraction of offspring surviving in each generation.


Observations
Observations food, and giraffes passed their stretched necks on to their offspring.

  • Observation #4: No two individuals in a population are exactly alike

  • Observation #5: Much of the observed variation in a population is heritable


Inference 2
Inference #2 food, and giraffes passed their stretched necks on to their offspring.

  • Survival in this "struggle for existence is not random, but depends, in part, on the hereditary makeup of the survivors.

  • Those individuals who inherit characteristics that allow them to best exploit their environment are likely to leave more offspring than individuals who are less well suited to their environment.


Inference 3
Inference #3 food, and giraffes passed their stretched necks on to their offspring.

  • Unequal reproduction between suited and unsuited organisms will eventually cause a gradual change in a population, with characteristics favorable to that particular environment accumulating over the generations.


So what is this theory of natural selection

SO WHAT IS THIS THEORY OF NATURAL SELECTION? food, and giraffes passed their stretched necks on to their offspring.

It can be broken down into four basic tenets, or ideas


Theory of natural selection
Theory of Natural Selection food, and giraffes passed their stretched necks on to their offspring.

1. Organisms are capable of producing huge numbers of offspring.

2. Those offspring are variable in appearance and function, and some of those variations are heritable.


Theory of natural selection1
Theory of Natural Selection food, and giraffes passed their stretched necks on to their offspring.

3. Environmental resources are limited, and those varied offspring must compete for their share.

4. Survival and reproduction of the varied offspring is not random. Those individuals whose inherited characteristics make them better able to compete for resources will live longer and leave more offspring than those not as able to compete for those limited resources.



Natural selection definition
Natural Selection Definition food, and giraffes passed their stretched necks on to their offspring.

Natural selection

is

differential success in reproduction

Selection can only edit existing variations


Evolution1
Evolution food, and giraffes passed their stretched necks on to their offspring.

  • Theory - an accepted hypothesis that has been tested over and over again without yet being disproved

  • Definition - Evolution is the change in the overall genetic makeup of a population over time

  • Three Basic Componentsa.  Individuals cannot evolve.  Populations evolve.b.  Natural selection is the mechanism of evolution.c.  Evolution occurs by chance (NOT GOAL ORIENTED).


Evolution2
Evolution food, and giraffes passed their stretched necks on to their offspring.

  • Populations are a group of interbreeding individuals belonging to the same species and sharing a common geographic area

  • Natural selection favors individuals, so multiple generations must be examined


What is speciation and who studies it
What is speciation and who studies it? food, and giraffes passed their stretched necks on to their offspring.

  • Speciation is the creation of a new species

  • Scientists who study the processes and mechanisms that lead to such speciation events are called EVOLUTIONARY BIOLOGISTS.


Species
Species food, and giraffes passed their stretched necks on to their offspring.

  • species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but are unable to produce viable fertile offspring with members of other populations


  • Macroevolution food, and giraffes passed their stretched necks on to their offspring.

  • the origin of new taxonomic

  • groups (new species, etc.)

  • + Anagenesis

  • - phyletic evolution

  • - transformation of one

  • species to another

  • + Cladogenesis

  • - branching evolution

  • - new species arise from a population that buds from a parent species

  • + increases biodiversity

(b) Cladogenesis

(a) Anagenesis


Sympatric speciation. food, and giraffes passed their stretched necks on to their offspring. A smallpopulation becomes a new specieswithout geographic separation.

Allopatric speciation. A population forms a new

species while geographically isolated from its parent population.

  • Speciation can occur in two ways

    • Allopatric speciation

    • Sympatric speciation


Allopatric speciation
Allopatric Speciation food, and giraffes passed their stretched necks on to their offspring.

  • A population becomes physically separated from the rest of the species by a geographical barrier that prevents interbreeding. 

  • Because gene flow is disrupted by this physical barrier, new species will form.


A. harrisi food, and giraffes passed their stretched necks on to their offspring.

A. leucurus


Sympatric speciation
Sympatric Speciation food, and giraffes passed their stretched necks on to their offspring.

  • Two populations are geographically close to each other, but they are reproductively isolated from each other by different habitats, mating seasons, etc.

  • Polyploidy

    • Is the presence of extra sets of chromosomes in cells due to accidents during cell division

    • Has caused the evolution of some plant species


Failure of cell division food, and giraffes passed their stretched necks on to their offspring. in a cell of a growing diploid plant afterchromosome duplicationgives rise to a tetraploidbranch or other tissue.

Offspring with tetraploid karyotypes may be viable and fertile—a new biological species.

Gametes produced by flowers on this branch will be diploid.

2n

2n = 6

4n

4n = 12

  • An autopolyploid

    • Is an individual that has more than two chromosome sets, all derived from a single species


Unreduced gamete food, and giraffes passed their stretched necks on to their offspring.

with 4 chromosomes

Unreduced gamete

with 7 chromosomes

Viable fertile hybrid

(allopolyploid)

Hybrid with

7 chromosomes

Meiotic error;

chromosome

number not

reduced from

2n to n

Species A

2n = 4

2n = 10

Normal gamete

n = 3

Normal gamete

n = 3

Species B

2n = 6

  • An allopolyploid

    • Is a species with multiple sets of chromosomes derived from different species


Reproductive barriers
Reproductive Barriers food, and giraffes passed their stretched necks on to their offspring.

A reproductive barrier is any factor that prevents two species from producing fertile hybrids, thus contributing to reproductive isolation.

  • Habitat Isolation

  • Temporal Isolation

  • Behavioral Isolation

  • Mechanical Isolation

  • Gametic Isolation


Reproductive Barriers food, and giraffes passed their stretched necks on to their offspring.

  • Prezygotic barriers

    • Impede mating between species or hinder the fertilization of ova if members of different species attempt to mate

  • Postzygotic barriers

    • Often prevent the hybrid zygote from developing into a viable, fertile adult


Prezygotic barriers impede mating or hinder fertilization if mating does occur

Behavioral isolation

Habitat isolation

Temporal isolation

Mechanical isolation

Individualsof differentspecies

Matingattempt

HABITAT ISOLATION

MECHANICAL ISOLATION

TEMPORAL ISOLATION

BEHAVIORAL ISOLATION

(g)

(b)

(d)

(e)

(f)

(a)

(c)

Prezygotic and postzygotic barriers


Gametic mating does occurisolation

Reducehybridfertility

Reducehybridviability

Hybridbreakdown

Viablefertileoffspring

Fertilization

REDUCED HYBRID VIABILITY

GAMETIC ISOLATION

HYBRID BREAKDOWN

REDUCED HYBRID FERTILITY

(k)

(j)

(m)

(l)

(i)

(h)

Prezygotic and postzygotic barriers


Adaptive radiation
Adaptive Radiation mating does occur

  • Adaptive Radiation - Evolutionary process in which the original species gives rise to many new species, each of which is adapted to a new habitat and a new way of life.  E.g. Darwin's Finches 



Evidence for evolution
Evidence for Evolution mating does occur

  • HOMOLOGY is a characteristic shared by two species (or other taxa) that is similar because of common ancestry.

  • Artificial Selection Farmers had been conducting this controlled breeding of livestock and crops for years in order to obtain the most milk from cows or the best cobs from corn plants.


Evidence for evolution1
Evidence for Evolution mating does occur

  • Paleontology - Study of Fossilsa.  Fossil - preserved evidence of past lifeb.  Radioactive Dating - method by which fossil age can be determined by the amount of organic matter remaining in the specimen.  This is possible because some substances break down at a known rate (half-life).


Types of homology
Types of homology mating does occur

  • morphological homology – species placed in the same taxonomic category show anatomical similarities.

  • ontogenetic homology - species placed in the same taxonomic category show developmental (embryological) similarities.

  • molecular homology - species placed in the same taxonomic category show similarities in DNA and RNA.


Morphological homology
MORPHOLOGICAL HOMOLOGY mating does occur

  • Structures derived from a common ancestral structure are called:

    HOMOLOGOUS STRUCTURES


Ontogenetic homology
Ontogenetic Homology mating does occur

The human embryo has gills, a post-anal tail, webbing between the toes & fingers, & spends its entire time floating and developing in amniotic fluid has similar salt concentration as ocean water


Pharyngeal mating does occur

pouches

Post-anal

tail

Chick embryo

Human embryo

Figure 22.15

ontogeny recapitulates phylogeny


Morphological homology1
MORPHOLOGICAL HOMOLOGY mating does occur

  • A structure that serves the same function in two taxa, but is NOT derived from a common ancestral structure is said to be an

    ANALOGOUS STRUCTURE


NORTH mating does occur

AMERICA

Sugar

glider

AUSTRALIA

Flying

squirrel

  • Some similar mammals that have adapted to similar environments

    • Have evolved independently from different ancestors


Examples of analogous structures
Examples of Analogous structures: mating does occur

  • wings of bat, bird, and butterfly

  • walking limbs of insects and vertebrates

  • cranium of vertebrates and exoskeleton head of insects

  • 4 chambered heart in birds & mammals


Molecular homology
Molecular Homology mating does occur


Types of evolution
Types of Evolution mating does occur

  • Divergent Evolution - Method of evolution accounting for the presence of homologous structures.  Multiple species of organisms descended from the same common ancestor at some point in the past.

  • Convergent Evolution - Method of evolution accounting for the presence of analogous structures.  Organisms of different species often live in similar environments, thus explaining the presence of features with similar functions.


An ongoing process
An ongoing process mating does occur

  • Evolution can be considered a process of "remodeling" a population over the course of many generations, with the driving force being the natural selection factors that favor one form over another in specific environments.


Vestigial structures
Vestigial mating does occurStructures

  • Have marginal, if any use to the organisms in which they occur.

  • EXAMPLES:

  • femurs in pythonid snakes and pelvis in cetaceans (whales)

  • appendix in humans

  • coccyx in great apes


Rate of evolution
Rate of Evolution mating does occur

  • Gradual evolution occurs where the increment of change is small compared to that of time.

  • Punctuated evolution occurs where the increment of change is very large compared to that of time in discrete intervals, while most of the time there is virtually no change at all.


  • Fitness mating does occur

    • Is the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals


Natural selection in action
Natural Selection in Action mating does occur

  • Industrial melanism


Natural selection in action1
Natural Selection mating does occur in Action

  • Camouflage


(a) A flower mantid mating does occurin Malaysia

(b) A stick mantidin Africa

Figure 22.11

  • If an environment changes over time

    • Natural selection may result in adaptation to these new conditions


Natural selection in action2
Natural Selection in Action mating does occur

  • Mimicry

  • Coral vs. King Snakes: Red on yellow, kill a fellow, red on black won’t hurt Jack


Natural selection in action3
Natural Selection in Action mating does occur

  • Mimicry

  • Monarch or Viceroy Butterfly


Natural selection in action4
Natural Selection in Action mating does occur

  • Warning Coloration


Natural selection in action5
Natural Selection in Action mating does occur

  • Disruptive Coloration


Natural selection in action6
Natural Selection in Action mating does occur

  • Counter Shading


Natural selection in action7
Natural Selection in Action mating does occur

  • Eye spots


Causes of evolution
Causes of Evolution mating does occur

  • Mutations - random changes in genetic material at the level of the DNA nucleotides or entire chromosomes

  • Natural Selection - most important cause of evolution; measured in terms of an organism's fitness, which is its ability to produce surviving offspring

    Modes of Selection

    a.  Stabilizing Selection - average phenotypes have a selective advantage over the extreme phenotypes

    b.  Directional Selection - phenotype at one extreme has a selective advantage over those at the other extreme

    c.  Disruptive Selection - both extreme phenotypes are favored over the intermediate phenotypes


Original population mating does occur

Frequency of individuals

Evolved

population

Phenotypes (fur color)

Original

population

These mice have colonized a

patchy habitat made up of light

and dark rocks, with the result

that mice of an intermediate

color are at a disadvantage.

If the environment consists of

rocks of an intermediate color,

both light and dark mice will

be selected against.

In this case, darker mice are favored

because they live among dark

rocks and a darker fur color conceals

Them from predators.

Modes of Selection


Causes of evolution1
Causes of Evolution mating does occur

3. Mating Preferences - Organisms usually do not choose their mates at random, thus the selection process can cause evolution

4.  Gene Flow - Transfer of genes between different populations of organisms.  This situation leads to increased similarity between the two populations (Tends to reduce differences between populations over time)

5.  Genetic Drift (Founder Effect & Bottleneck) - Situation that results in changes to a population's gene pool caused by random events, not natural selection.  This situation can have drastic effects on small populations of individuals.  Common on islands.


Gene flow
Gene Flow mating does occur


Genetic drift
Genetic Drift mating does occur


Founder effect
Founder Effect mating does occur


Bottleneck effect
Bottleneck Effect mating does occur


Bottlenecking a population of organisms tends to reduce genetic variation, as in these northern elephant seals in California that were once hunted nearly to extinction.

  • Understanding the bottleneck effect

    • Can increase understanding of how human activity affects other species


Note the difference
Note the Difference genetic variation, as in these northern elephant seals in California that were once hunted nearly to extinction.

  • Macroevolution

  • -Evolutionary change above the species level e.g. the appearance of feathers on dinosaurs

  • Macroevolutionary change

    • Is the cumulative change during thousands of small speciation episodes

  • Microevolution

    • Is change in the genetic makeup of a population from generation to generation


  • Population genetics genetic variation, as in these northern elephant seals in California that were once hunted nearly to extinction.

    • Is the study of how populations change genetically over time

  • Population geneticists

    • Measure the number of polymorphisms in a population by determining the amount of heterozygosity at the gene level and the molecular level

  • Average heterozygosity

    • Measures the average percent of loci that are heterozygous in a population



Generation most evolutionary change

1

CWCW

genotype

CRCR

genotype

Plants mate

Generation

2

All CRCW

(all pink flowers)

50% CR

gametes

50% CW

gametes

Come together at random

Generation

3

25% CRCR

50% CRCW

25% CWCW

50% CR

gametes

50% CW

gametes

Come together at random

Generation

4

25% CRCR

25% CWCW

50% CRCW

Alleles segregate, and subsequent

generations also have three types

of flowers in the same proportions

Figure 23.4


  • Hardy-Weinberg Theorem most evolutionary change

  • genetic structure of a non-evolving

  • population remains constant

  • + sexual recombination cannot alter

  • the relative frequencies of alleles

  • - Hardy-Weinberg equilibrium

  • Hardy-Weinberg equation

  • p2 + 2pq + q2 = 1

  • p2: frequency of AA genotype

  • 2pq: frequency of Aa genotype

  • q2: frequency of aa genotype

  • - p: frequency of A allele

  • - q: frequency of a allele


Hardy weinberg
Hardy-Weinberg most evolutionary change

  • HW law states --> original of a genotypes alleles remains CONSTANT

  • HW Equilibrium... is defined algebraically

    any gene with 2 allelic forms... A and a

  • let frequency of one allele (A) = p & frequency of other allele (a) = q

  • then by definition, p + q = 1

  • HW equation... (p + q)2 = p2 + 2 pq + q2 = 1

  • AA Aa aa


mechanisms that help to preserve genetic variation in a population

  • Diploidy

    • Maintains genetic variation in the form of hidden recessive alleles

  • Heterozygote Advantage

  • Individuals who are heterozygous at a particular locus have greater fitness than homozygotes

  • Natural selection

    • Will tend to maintain two or more alleles at that locus


Heterozygote Advantage population

Plasmodium falciparum

AA = No sickle (Dead from malaria)

Aa = sickle trait

aa = sickle disease (Dead)


Sexual reproduction population

Asexual reproduction

Generation 1

Female

Female

Generation 2

Male

Generation 3

Generation 4

Sexual reproduction

Produces fewer reproductive offspring than asexual

reproduction, a so-called reproductive handicap



Phylogeny
Phylogeny population

  • The evolutionary history of a species or group of related species depicted as a branching tree

  • Each branch represents a new species which inherits many (primitive) traits from the ancestor but also has a new (derived) trait which appear for the 1st time


Systematics
Systematics population

  • An analytical approach to understanding the

    diversity and relationships of organisms, both

    present-day and extinct

Morphological, biochemical, and molecular

comparisons are used to infer evolutionary

relationships


  • The fossil record population

    • Is based on the sequence in which fossils have accumulated in such strata

  • Fossils reveal

    • Ancestral characteristics that may have been lost over time


Diversity of Life Learned Through the Fossil Record population

  • Mass Extinctions

  • extinction is inevitable

  • in a changing world

  • + extinctions open up

  • new adaptive zones

  • - new living

  • conditions,

  • resources, and

  • opportunities


Dating Fossils population

  • Relative Dating

  • tells the order in which groups of species were present in a sequence of strata (before/after, early/late)

  • + index fossils

  • - fossils that permit the relative dating of rocks within a narrow time span

  • Absolute Dating

  • dating that provides the age of fossils in years

  • + radiometric dating

  • - use of radioactive isotopes to date specimens (Carbon-14)


Leaf fossil, about 40 million years old population

Petrified tree in Arizona, about 190 million years old

Dinosaur bones being excavated from sandstone

Casts of ammonites, about 375 million years old

Insects preserved whole in amber

Boy standing in a 150-million-year-old dinosaur track in Colorado

Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice


  • In addition to fossil organisms population

    • Phylogenetic history can be inferred from certain morphological and molecular similarities among living organisms

  • In general, organisms that share very similar morphologies or similar DNA sequences

    • Are likely to be more closely related than organisms with vastly different structures or sequences


1 population Ancestral homologous DNA segments are identical as species 1 and species 2 begin to diverge from their common ancestor.

C C A T C A G A G T C C

1

C C A T C A G A G T C C

2

Deletion

2 Deletion and insertion mutations shift what had been matching sequences in the two species.

1

C C A T C A G A G T C C

C C A T C A G A G T C C

2

Insertion

G T A

3 Homologous regions (yellow) do not all align because of these mutations.

C C A T C A A G T C C

1

C C A T G T A C A G A G T C C

2

4 Homologous regions realign after a computer program adds gaps in sequence 1.

C C A T C A A G T C C

1

C C A T G T A C A G A G T C C

2

  • Systematists use computer programs and mathematical tools

    • When analyzing comparable DNA segments from different organisms


Sorting Homology from Analogy population

  • A potential misconception in constructing a phylogeny

    • Is similarity due to convergent evolution, called analogy, rather than shared ancestry

  • Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary

  • Analogous structures or molecular sequences that evolved independently

    • Are also called homoplasies


  • Binomial nomenclature

    • Is the two-part format of the scientific name of an organism

    • Was developed by Carolus Linnaeus


Classification based on physical and structural similarities evolutionary history

  • Carolus Linnaeus (1707-1778)

  • Created binomial nomenclature (2 word naming system)

  • 1st word = Genus (genera if plural) = a group of similar species

  • 2nd word = specific epithet = Species

  • Scientific name = Genus + specific epithet e.g. Homo sapiens


Writing Species Names evolutionary history

  • Rules for writing species names

  • Latin is the language of scientific names (Latin is no longer spoken, so it does not change)

  • Italicize in print and underline when hand written

  • 1st letter of the genus is CAPITALIZED & 1st letter of specific epithet is lowercase


Writing Species Names evolutionary history

Canis latrans = Coyote

Canis lupus = Grey wolf


Cougar? evolutionary history

Puma?

Panther?

Catamount?

Mountain lion? Or…

Felis concolor?


Taxonomic Rankings evolutionary history

  • Domain Did

  • Kingdom Kinky

  • Phylum Phil

  • Class Come

  • Order Over

  • Family For

  • Genus Good

  • Species Sex



Six Kingdoms evolutionary history

Protista

·Eukoryotic

·Autotrophs and heterotrophs

·Lacks organs systems

·Lives in moist environments

·Unicellular or multicellular

Fungi

·Eukaryotic

·Heterotrophs

·Unicellular or multicellular

·Absorbs nutrients from organic material in its environment

·Unicellular or multicellular

Eubacteria

·Prokaryotic

·True bacteria

·RNA is simple

·Have true cell walls

·Unicellular

Archaebacteria

·Prokaryotic

·RNA more complex

·Unicellular


Six Kingdoms evolutionary history

Plantae

·Eukaryotic

·Autotrophs

·Multicellular

·Photosynthetic

Animalia

·Eukaryotic

·Heterotrophs

·Multicellular


Panthera pardus(leopard)

Mephitis mephitis (striped skunk)

Canis familiaris (domestic dog)

Canislupus (wolf)

Lutra lutra (European otter)

Species

Genus

Panthera

Lutra

Canis

Mephitis

Family

Felidae

Mustelidae

Canidae

Carnivora

Order


Domestic evolutionary history

cat

Leopard

Common ancestor

  • Each branch point

    • Represents the divergence of two species


  • evolutionary historyDeeper” branch points

    • Represent progressively greater amounts of divergence

Domestic

cat

Wolf

Leopard

Common ancestor


Cladistics Vocabulary evolutionary history

  • Phylogenetic systematics informs the construction of phylogenetic trees based on shared characteristics

  • A cladogram

    • Is a depiction of patterns of shared characteristics among taxa

  • A clade within a cladogram

    • Is defined as a group of species that includes an ancestral species and all its descendants

  • Cladistics

    • Is the study of resemblances among clades


Cladistics Vocabulary evolutionary history

  • Character -- Heritable trait possessed by an organism

  • Nodes --The points of branching within a cladogram.


  • Clades evolutionary history

    • Can be nested within larger clades, but not all groupings or organisms qualify as clades

  • MONOPHYLETIC (Only VALID clade)

  • taxon includes all descendent species along with their immediate

  • common ancestor

  • POLYPHYLETIC

  • (b) taxon includes species derived from two different immediate

  • ancestors

  • PARAPHYLETIC

  • (c) taxon includes species A without incorporating all other descendants


Evolutionary Classification evolutionary history

  • Phylogeny - evolutionary history of a group of organisms

  • Cladistics – The study of evolutionary relationships between groups to construct their family tree based on characters

  • Derived characters – Characteristics which appear in recent parts of a lineage but NOT in its older members (Evolutionary innovation)


Most recent common ancestor – evolutionary history

The ancestral organism from which

a group of descendants arose.


Cladistics Vocabulary evolutionary history

  • A shared primitive character

    • Is a homologous structure that predates the branching of a particular clade from other members of that clade

    • Is shared beyond the taxon we are trying to define

  • A shared derivedcharacter

    • Is an evolutionary novelty unique to a particular clade


  • Outgroup comparison

    • Is based on the assumption that homologies present in both the outgroup and ingroup must be primitive characters that predate the divergence of both groups from a common ancestor


Cladistics Vocabulary evolutionary history

  • Ingroup -- In a cladistic analysis, the set of taxa which are hypothesized to be more closely related to each other than any are to the outgroup.


Characters & Character Table evolutionary history


  • Systematists evolutionary history

    • Can never be sure of finding the single best tree in a large data set

    • Narrow the possibilities by applying the principles of maximum parsimony and maximum likelihood

The most parsimonious tree is the one that

requires the fewest evolutionary events to

have occurred in the form of shared derived

characters


Mushroom evolutionary history

Tulip

Human

Human

30%

0

40%

Mushroom

40%

0

0

Tulip

(a) Percentage differences between sequences

  • Applying parsimony to a problem in molecular systematics


Bird evolutionary history

Lizard

Mammal

Four-chamberedheart

(a) Mammal-bird clade

Bird

Lizard

Mammal

Four-chamberedheart

Four-chamberedheart

(b) Lizard-bird clade

  • The principle of maximum likelihood

    • States that, given certain rules about how DNA changes over time, a tree can be foundthat reflects the most likely sequence of evolutionary events

  • Sometimes there is compelling evidence

    • That the best hypothesis is not the most parsimonious


  • Gene duplication evolutionary history

    • Is one of the most important types of mutation in evolution because it increases the number of genes in the genome, providing further opportunities for evolutionary changes

Homeotic or Hox genes, when duplicated can lead to new appendage arrangement (Vertebrate Evolution from Invertebrates)


  • The tree of life evolutionary history

    • Is divided into three great clades called domains: Bacteria, Archaea, and Eukarya

  • The early history of these domains is not yet clear

Archaea

Bacteria

Eukarya


Most invertebrates have one cluster of homeotic evolutionary historygenes (the Hox complex), shown here as coloredbands on a chromosome. Hox genes direct development of major body parts.

A mutation (duplication) of the single Hox complex occurred about 520 million years ago and may have provided genetic material associated with the origin of the first vertebrates.

First Hox

duplication

5

1

3

4

2

In an early vertebrate, the duplicate set of genes took on entirely new roles, such as directing the development of a backbone.

Hypothetical

vertebrate

ancestor

(invertebrate)

with a single

Hox cluster

A second duplication of the Hox complex, yielding the four clusters found in most present-day vertebrates, occurred later, about 425 million years ago. This duplication, probably the result of a polyploidy event, allowed the development of even greater structuralcomplexity, such as jaws and limbs.

Second Hox

duplication

Hypothetical early

vertebrates

(jawless)

with two Hox

clusters

The vertebrate Hox complex contains duplicates of many ofthe same genes as the single invertebrate cluster, in virtuallythe same linear order on chromosomes, and they direct the sequential development of the same body regions. Thus, scientists infer that the four clusters of the vertebrate Hoxcomplex are homologous to the single cluster in invertebrates.

Vertebrates

(with jaws)

with four Hox clusters

  • The evolution of vertebrates from invertebrate animals

    • Was associated with alterations in Hox genes


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