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Evolution Series: Set 3Version: 2.0Copyright © 2005

What is ___________?What is evolution?

Permanent genetic change (change in gene frequencies) in populations of individuals.

IDoes not refer to changes occurring to individuals within their own lifetimes.

______________________________.

____________________: small-scale changes within gene pools over generations.

______________________: large scale changes in form, as viewed in the fossil record, involving whole groups of species and genera.

The Modern Theory of Evolution

Combines the following ideas:

Darwin’s theory of the origin of species by_______________________.

Understanding of ________________________-Mendel

______________________________basis of heredity-Weismann

Darwin

+Mendel

+Weismann

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The Concepts of ____________“_______________________________:” descendants of ancestral forms adapt to different environments over long periods of time.

Mechanism for adaptation is “______________________”

Bases for Natural Selection:

______________________

_______________________

_______________________

___________________________

_______________________________

Natural Selection

______________Variations are inherited. The best suited variants

leave more offspring.

_______________Natural selection favors

the best suited at the time

__________________Individuals show variation: some

variationsare more favorable than others

_________________Populations produce too

many young: many must die

Evidence for EvolutionEvidence comes from many sources:

__________________________: identification,interpretation & dating of fossils--some of the most directevidence of evolution.

____________________: study of embryonic developmentin different organisms & its genetic control.

_______________________: study of the morphologyof different species.

Comparative anatomy

Paleontology

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The ________RecordA _______________, but incomplete, record of evolutionary history:

__________________ species can be traced through fossil relatives to ___________ origins.

_____________species often similar to, but differ from, __________________ species.

_________________types often differ between__________________________rock layers.

Numerous _________species found as fossils.

Fossils can be ___________to establish their approximate absolute ___________.

____________fossil types mark changes in past ________________conditions on Earth.

Rates of evolution can vary, with bursts of species formation followed by stable periods.

These fossil teeth, from Mastodon, an extinct elephant, are similar to the

deciduous teeth of modern elephants.

The Archaeopteryx FossilEight well-preserved fossil specimens have been discovered in fine-grained limestone in Germany (dated late Jurassic, about 150 million years ago).

Avian Features

Vertebrae are almost flat-faced.

Impressions of feathers attached to the forelimb.

Belly ribs.

Incomplete fusion of the lower leg bones.

Impressions of feathers attached to the tail.

Forelimb has three functional fingers with grasping claws.

Reptilian Features

Lacks the reductions and fusions present in other birds.

Breastbone is small and lacks a keel.

True teeth set in sockets in the jaws.

The hind-limb girdle is typical of dinosaurs, although modified.

Long, bony tail.LEFT: Archaeopteryx lithographicaFound in 1877 near Blumenberg, Germany

Fossils in a __________Profile

_______________ rock layers arranged in order in which deposited

the most ___________ layers nearer the ________.

layers can be disturbed by tectonic activity.

Rock layers containing fossils allows us to arrange fossils in _____________________(order of occurrence),

Does not give _______________date. Only primitive

fossils are found in older sediments

New fossil types mark changes in environment

Fossil types differ in each sedimentary rock layer

Numerous extinct species

Recent fossils are found in recent sedimentsMost recent

sediments

Oldest sediments

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_______________ FossilsRelative age of fossils is useful, but fossils provide reliable historical data only if we can determine their absolute age.

A number of methods are used to date fossils.

A fossil trilobite, a primitive arthropod that dwelled in the seas of the Devonian period 370 million years ago

Dating Method Age Range (years) Material Dated

Electron Spin Resonance 500 000 – 1000Bone, tooth enamel,

cave deposits

Fission Track 1 million – 100 000 Volcanic rock

Obsidian Hydration 800 000 – presentObsidian

(volcanic glass)

Amino acid racemization 1 million – 2000 Bone

Thermoluminescence less than 200 000Pottery, fired clay,

bricks, burned rock

Uranium/Thorium Less than 350 000 Bone, tooth dentine

Carbon 14 1000 – 50 000+Bone, shell,

charcoal

Potassium/Argon 10 000 – 100 million Volcanic rocks

____________________ Anatomy

5 digit limbs found in most vertebrates have the same general ___________________.

Similarity of structure is called ______________.

Homologies indicated _____________ancestry.

Femur (thigh)

Fibula

Tibia

Tarsals(ankle)

Metatarsals(sole)

Phalanges(toes)

Hind LimbForelimb

Humerus(upper arm)

Ulna

Radius

Carpals(wrist)

Metacarpals(palm)

Phalanges(fingers)

Note that forelimbs and hind limbs have different

names for equivalent bones.

________________Structures

Basic 5-digit limb has been highly modified to serve specialized functions.

Such homologies also indicate ___________________

Basic limb plan has been adapted to meet the needs of different niches.

Bird's wing

Bat's wing

Human arm

Dog's front leg

Mole's forelimb

Seal's flipper

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__________________ Structures

Not all _____________ inherited from a ________________ancestor.

Structures having same function in different organisms may come from different origins. This phenomenon is termed “analogy.”

______________structures do notimply evolutionary relationships,may indicate ___________. Examples:

Eye structure in octopus and mammals.

Wings in birds and butterflies.

Fins in fish and flippers in mammals

Fins

Flippers

Wings

______________________________Organs

_______________________structures that no longer perform the same function as in other organisms.

These organs must have been important in some ancestral form, but became ___________________________.

Selection pressure for complete loss is weakso the structures remain

__________________________ apparentlyhave little use, may perform somesecondary function.

Kiwis: wings

Snakes: pelvic girdle and hind limbs.

Eyes of burrowing animals no longer used for vision.

Appendix in humans

Wisdom teeth

Face & Ear Muscles

Vestigial Organs in __________Descendants of large, four-legged land mammals

took up an aquatic existence some 60 million years ago.

Over many millions of years, the pelvis and femur of whales have become very small and no longer fulfill a locomotory function.

Pelvis

Femur

Hindlimb

Forelimb

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____________________Evidence

________________________ distribution

Basic principle-- each plant and animal species originated only once. The place where this occurred is the centre of origin.

The range of a species can be very restricted or, as with humans, almost the whole world (cosmopolitan).

Regions that have been separated from the rest of the world for a long time (e.g. Madagascar, Australia, and New Zealand), often have distinctive biota comprising a large number of endemic species (species that are found nowhere else).

Lemurs are endemic to the island of Madagascar

Map: University of Texas at Austin (Public Domain image)

______________________________

Distribution of species around the world suggests that ____________________________________and spread out (radiated) out into new environments.

Good examples are found on _______________________________________________________________________:

Galapagos Islands

Cape Verde Islands

Tristan da Cunha

______________________

Species thought to be closely related on other evidence found to have greater _____________________of DNA __________________in common.

Humans and chimpanzees have a ______________________ in their DNA sequences and are very closely related.

DNA of humans and chimpanzees more closely matched than __________________________________________________________.

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___________________________Sequences of amino acids in certain proteins(e.g. ___________________ and ________________________) have revealed great similarities and specific differences between species.

_______________ related species have proteinswith _______________________________________.

Amino acid sequences are determined by ___________________________ & differences are due to ___________________________.

degree of similarity determined number of mutations

_________________________related species have had more time for ________________________________

Hemoglobin

Amino acidsAla

Ala

Ala

Met Gly

Glu

Glu

Phe

Iso

Ser

Tyr

Phe

PrimateNo. of amino acids

different from

humans

Position ofchanged amino acids

Chimpanzee Identical –

Gorilla 1 104

Gibbon 3 80 87 125

Rhesus monkey 8 9 13 33 50 76 87 104 125

Squirrel monkey 9 5 6 9 21 22 56 76 87 125

___________________________Amino acid differences for beta-hemoglobin in primates compared to the human sequence:

The 'position of changed amino acids' is the point in the protein,

composed of 146 amino acids, at which a different amino acid occurs.

GibbonSquirrel monkey

Gorilla

Chimpanzee

Rhesus monkey

_____________________ Evidence

Relationships of a large number of different animal groups have been established on basis of immunology.

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Various “forces” or phenomenon are at play in the evolutionary process:

At the ________________ level:

____________________

Control of gene expression

Rate of ___________________

UV LightForces Operating in Evolution

At the ____________level:

_____________________

______________mutations

Polyploidy

Aneuploidy

______________________

______________________

Sperm

Egg

Forces Operating in Evolution

Forces Operating in Evolution

At the _____________level:

Environmental modificationof phenotype

Reproductive success

Selection pressures

'Fitness' of the phenotype

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At the _____________ level:

Genetic drift and population size

_____________ altering gene frequencies

__________ selection

___________competition

_______________ effect

______________________(gene flow)

Forces Operating in Evolution

AA

AA

AA

AA

AA

AA

Aa

Aa

Aa

Aa

Aa

Aa

aa

aa

aa

aa

At the _____________level:

______________ barriers

________________isolation (prezygotic and postzygotic)

_______________pressures

_____________competition

Forces Operating in Evolution