Evolution
This presentation is the property of its rightful owner.
Sponsored Links
1 / 164

Evolution PowerPoint PPT Presentation


  • 152 Views
  • Uploaded on
  • Presentation posted in: General

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)

Download Presentation

Evolution

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


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


Evolution

Why the controversy?


Intelligent design vs evolution

Intelligent Design vs Evolution


Evolution

  • 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


Evolution

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


Evolution

  • 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


Evolution

  • 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!


Where did darwin and wallace get the idea of evolution

Where did Darwin and Wallace get the idea of evolution?


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”

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


Georges cuvier 1769 1832

Georges Cuvier(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(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 (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(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 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

  • 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

  • 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

  • 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

  • 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?

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


Theory of natural selection

Theory of Natural Selection

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

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.


Evolution

  • Natural selection is differential success in reproduction

    • That results from the interaction between individuals that vary in heritable traits and their environment


Natural selection definition

Natural Selection Definition

Natural selection

is

differential success in reproduction

Selection can only edit existing variations


Evolution1

Evolution

  • 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

  • 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?

  • 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

  • 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


Evolution

  • Macroevolution

  • 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


Evolution

Sympatric speciation. 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

  • 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.


Evolution

A. harrisi

A. leucurus


Sympatric speciation

Sympatric Speciation

  • 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


Evolution

Failure of cell divisionin 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


Evolution

Unreduced gamete

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

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


Evolution

Reproductive Barriers

  • 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


Evolution

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


Evolution

Gameticisolation

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

  • 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 


Adaptive radiation of hominids

Adaptive Radiation of Hominids


Evidence for evolution

Evidence for Evolution

  • 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

  • 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

  • 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

  • Structures derived from a common ancestral structure are called:

    HOMOLOGOUS STRUCTURES


Ontogenetic homology

Ontogenetic Homology

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


Evolution

Pharyngeal

pouches

Post-anal

tail

Chick embryo

Human embryo

Figure 22.15

ontogeny recapitulates phylogeny


Morphological homology1

MORPHOLOGICAL HOMOLOGY

  • 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


Evolution

NORTH

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:

  • 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


Types of evolution

Types of Evolution

  • 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

  • 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

VestigialStructures

  • 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

  • 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.


Evolution

  • Fitness

    • 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

  • Industrial melanism


Natural selection in action1

Natural Selection in Action

  • Camouflage


Evolution

(a)A flower mantidin 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

  • 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

  • Mimicry

  • Monarch or Viceroy Butterfly


Natural selection in action4

Natural Selection in Action

  • Warning Coloration


Natural selection in action5

Natural Selection in Action

  • Disruptive Coloration


Natural selection in action6

Natural Selection in Action

  • Counter Shading


Natural selection in action7

Natural Selection in Action

  • Eye spots


Causes of evolution

Causes of Evolution

  • 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


Evolution

Original population

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

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


Genetic drift

Genetic Drift


Founder effect

Founder Effect


Bottleneck effect

Bottleneck Effect


Evolution

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

  • 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


Evolution

  • Population genetics

    • 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


Evolution

  • Three major factors alter allele frequencies and bring about most evolutionary change

    • Natural selection

    • Genetic drift

    • Gene flow


Evolution

Generation

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


Evolution

  • Hardy-Weinberg Theorem

  • 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

  • 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


Evolution

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


Evolution

Heterozygote Advantage

Plasmodium falciparum

AA = No sickle (Dead from malaria)

Aa = sickle trait

aa = sickle disease (Dead)


Evolution

Sexual reproduction

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


Evolution

  • If sexual reproduction is a handicap, why has it persisted?

    • It produces genetic variation that may aid in disease resistance


Phylogeny

Phylogeny

  • 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

  • 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


Evolution

  • The fossil record

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

  • Fossils reveal

    • Ancestral characteristics that may have been lost over time


Evolution

Diversity of Life Learned Through the Fossil Record

  • Mass Extinctions

  • extinction is inevitable

  • in a changing world

  • + extinctions open up

  • new adaptive zones

  • - new living

  • conditions,

  • resources, and

  • opportunities


Evolution

Dating Fossils

  • 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)


Evolution

Leaf fossil, about 40 million years old

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


Evolution

  • In addition to fossil organisms

    • 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


Evolution

1Ancestral 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

2Deletion 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

3Homologous 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

4Homologous 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


Evolution

Sorting Homology from Analogy

  • 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


Evolution

  • Phylogenetic systematics connect classification with evolutionary history

  • Taxonomy

    • Is the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences

  • Binomial nomenclature

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

    • Was developed by Carolus Linnaeus


Evolution

Classification based on physical and structural similarities

  • 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


Evolution

Writing Species Names

  • 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


Evolution

Writing Species Names

Canis latrans = Coyote

Canis lupus = Grey wolf


Evolution

Cougar?

Puma?

Panther?

Catamount?

Mountain lion? Or…

Felis concolor?


Evolution

Taxonomic Rankings

  • Domain Did

  • Kingdom Kinky

  • Phylum Phil

  • Class Come

  • Order Over

  • Family For

  • Genus Good

  • Species Sex


Evolution

  • All Living Organisms are grouped into... 3 DOMAINS

  • EUBACTERIA-   true bacteria

  • ARCHAEA-   ancient prokaryotes       

  • EUCARYA -  modern eukaryotes


Evolution

Six Kingdoms

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


Evolution

Six Kingdoms

Plantae

·Eukaryotic

·Autotrophs

·Multicellular

·Photosynthetic

Animalia

·Eukaryotic

·Heterotrophs

·Multicellular


Evolution

  • Systematists depict evolutionary relationships

    • In branching phylogenetic trees

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


Evolution

Domestic

cat

Leopard

Common ancestor

  • Each branch point

    • Represents the divergence of two species


Evolution

  • “Deeper” branch points

    • Represent progressively greater amounts of divergence

Domestic

cat

Wolf

Leopard

Common ancestor


Evolution

Cladistics Vocabulary

  • 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


Evolution

Cladistics Vocabulary

  • Character -- Heritable trait possessed by an organism

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


Evolution

  • Clades

    • 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


Evolution

Evolutionary Classification

  • 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)


Evolution

Most recent common ancestor –

The ancestral organism from which

a group of descendants arose.


Evolution

Cladistics Vocabulary

  • 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


Evolution

  • Systematists use a method called outgroup comparison

    • To differentiate between shared derived and shared primitive characteristics

  • 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


Evolution

Cladistics Vocabulary

  • 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.


Evolution

Characters & Character Table


Evolution

  • Systematists

    • 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


Evolution

Mushroom

Tulip

Human

Human

30%

0

40%

Mushroom

40%

0

0

Tulip

(a) Percentage differences between sequences

  • Applying parsimony to a problem in molecular systematics


Evolution

Bird

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


Evolution

  • Gene duplication

    • 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)


Evolution

  • The tree of life

    • 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


Evolution

Most invertebrates have one cluster of homeotic genes (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


  • Login