Biology 3.5 - PowerPoint Presentation

Slide1

Biology 3.5

Patterns of Evolution

Credits: 4

ExternalSlide2

! Before we begin…From the examination specifications…Slide3
Slide4
Slide5
Slide6
Slide7
Slide8

Giraffe Evolution?Slide9
Slide10
Slide11
Slide12
Slide13
Slide14

Revision12 bio stuff…Slide15

Stuff u should know from Year 12Natural SelectionDirectionalDisruptive

StabilisingFounder effectPopulation bottlenecksGenetic driftMutation

Gene flow

Migration

Factors affecting allele frequencies…Slide16

Darwin vs LamarckSlide17

Natural Selection in a NutSHELL

Variation

Individuals vary in phenotype (physical traits). Some variants are better suited to the current environmental conditions. The better suited survive better and leave more offspring.

Natural Selection

The alleles of the better suited increase in the population, they are said to be ‘selected for’.

Inheritance

Variations are passed on to offspring. If the selection pressure is maintained each new generation contains proportionally more descendants from individuals with favourable characteristics than those with unfavourable.

Some variation is lost.Slide18

Natural Selection

Requires:VariationSelective Pressure

Inheritance

Result:

Selection of the ‘fittest’ variants and their genes.Slide19

Bio 3.5Level 3 from hereSlide20

The “Species” Concept“a group of actually or potentially interbreeding natural populations that is reproductively isolated from other such groups”

Main Problem:- Closely related species produce fertile offspring eg

Canis

spp.

Genetically isolated species may be morphologically similar = cryptic species (morph = “body”)

Main Solution:

Use DNA analysis to clarify relationships between closely related species.

BUT: how much difference = different species, subspecies….??

Extinct: 10,000 years bpSlide21
Slide22

Clines & Ring SpeciesCline: A

gradation in one or more characteristics within a species esp. between different populations.

Ring Species:

A series

of

neighbouring

populations that can

interbreed, but

for which there exist at least two "end" populations in the series that are too distantly related to interbreed

In this diagram, interbreeding populations are represented by coloured blocks.

Variation

along a cline may bend right around, forming a ring.Slide23

Larus (gull) ring species

The

Larus

gulls interbreed in a ring around the arctic

(1 :

Larus argentatus argentatus

, 2:

Larus fuscus sensu stricto

, 3 :

Larus fuscus heuglini

, 4 :

Larus argentatus birulai

, 5 :

Larus argentatus vegae

, 6 :

Larus argentatus smithsonianus

, 7 :

Larus argentatus

argenteus

Neighbouring groups can hybridise (breed together) but sufficient differences exist to prevent groups 1 & 7 breeding.

A Herring Gull,

Larus argentatus

(front) and a Lesser Black-backed Gull.

Larus fuscus

(

behind

)

Are you my type?

No, gull away!Slide24

Californian Salamander Ring Species

The many subspecies of Ensatina salamanders in California exhibit subtle morphological and genetic differences all along their range. They all interbreed with their immediate neighbours

with one exception: where the extreme ends of the range overlap in Southern California,

E.

klauberi

and

E.

eschscholtzii

do not interbreed.

So

where do we mark the point of speciation? Slide25

Stages in Species Development #1Species rarely explode suddenly into existence (species formation is usually slow)General pattern:

Homogenous population splits (cause = geographical barrier) Different natural selection pressures, mutations  gene frequencies change

Races form as gene flow reduces, factors preventing mating begin (“

prezygotic

”)

Gene flow further reduces, post zygotic factors occur (hybrid sterility –

eg

as in mule)

Now = two different species.Slide26

Variation in Human Skin ColourSlide27

Stages in Species Development #2- A generally predictable series of events occurs as a homogenous ancestral population evolves into two separate species.

- The key to this is build up of genetic differences as a population is split into two populations. Barriers to frequent mating mean that differing natural selection pressures and mutations are not shared  populations go down different genetic pathways.

- Eventually differences build to where the populations become separate races.

- With enough differences races become difference subspecies, then separate species.

Slide28

Extinction

Sumatran tiger:

http://

en.wikipedia.org/wiki/Sumatran_tiger

Sumatran tiger clip:

http://

www.theawl.com/2011/05/get-a-good-look-at-these-awesome-tigers-theyre-almost-extinct

Call of Life (extinction

video trailer):

http://

www.calloflife.org/p-trailer.htm

Extinction

Sumatran tigerSlide29

ExtinctionA natural process – all species that have evolved will eventually go extinct

Duration of persistence of a species varies (often from 1 million years for complex organisms to 10-12 million years for simple organisms)Extinction and mass extinction provides opportunities for other organisms to evolve and fill vacant ecological niches.

Humans: How long have we been around? When will we become extinct?

Anatomical modernity: 200,000 years ago

Behavioural modernity: 50,000 years ago

Future…”currently using resources at rate of 8 planets worth”

“Fred” a preserved dodo,

Raphus cucullatus

Haasts Eagle & moa

HuiaSlide30

CoelacanthCoelacanths were thought to have gone extinct in the Late

Cretaceous (~65mya), but were rediscovered in 1938 off the coast of South Africa. 2 Known extant species. The coelacanth has been nicknamed a “living fossil”, because its fossils were found long before the actual discovery of a live specimen

.

The coelacanth is thought to have first evolved approximately 400 million years ago

.

Latimeria

chalumnae

(60kg, 170cm long)Slide31

Processes of EvolutionSlide32

The Role of MutationNotes + BZ90,92-98Slide33

The Role of Gene FlowNotes + BZBLB 158-160Slide34

Oligocene Drowninghttp://www.odt.co.nz/lifestyle/magazine/251158/theory-floundershttp://www.stuff.co.nz/environment/215430/NZ-was-never-underwater-scientistsSlide35

Kiwi an Australian?http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11259906http://www.adelaide.edu.au/news/news70682.htmlSlide36

Speciation“Process by which one species gives rise to two or more new species”

 Multiplication of spp. not gradual change over timeSlide37

Allopatric Speciation

Usually:Pops get geographically separated (eg by river) 

Gene flow

reduces,

Genetic isolation occurs.

Diffs in natural selection can cause diffs in allele frequencies between the pops over time

. AND: mutations occurring in one population will not be transferred by migration to other populations (no gene flow)

Diffs

accumulate

, when the pops are reunited

they may now no longer interbreed

= separate spp.

NZs isolation/islands has led to many egs of allopatric speciation

. (changing sea levels, mountain building, ice ages have also had an impact)Slide38

Allopatric SpeciationSlide39

Allopatric Speciation: Snapping Shrimp Example15 different species of shrimp on EACH side of the Isthmus of Panama (3mya). How could this occur?

In a single population of shrimp (before the isthmus), a mutation that arose in one individual could eventually spread through the whole population as the shrimp mated with each other. But once there is a

barrier

splitting the population in half, a new mutation can only spread through half the population.

That is

why a lack of interbreeding means the two populations evolve separately.

There can also be slightly different factors for survival in the different areas: maybe the temperature or currents are different on each side; maybe the food sources are different.

This

can also help the populations

diverge

, or become different, from each other. Slide40

Reptiles again…Slide41

Allopatric Speciation Questions

1. Why have many NZ birds lost the ability to fly (cf to their Aussie relatives)?2. Glaciation creates many isolated mountaintops – how would this contribute to allopatric speciation?

3. How could sea level rise/fall create new species through allopatric speciation?

4. Describe how an ancestral robin species gave rise to the Chatham Island robin and the mainland robin

.

5. Describe ALL potential geographical barriers (read the sheet “geographical barriers”

6. Explain how one NZ plant and one NZ animal came about as a result of allopatric speciation (read the sheet “allopatric speciation in NZ animals and plants”Slide42

Sympatric Speciation‘speciation NOT involving a period of geographic separation”Much rarer than allopatric speciation

More common in plantsRest of notes on OHT (sigh)Slide43

Nonallopatric Speciation occurs with no evidence of physical barriers

Geography is not the only way a population can separate

The

huge variety of cichlid fishes in African lakes are found nowhere else; yet

the lakes

are evolutionarily young and without

barriers.

Individuals

can

speciate

while living in different components of the environment. African cichlid fishes show very different feeding specializations

Slide44
Slide45

PolyploidySlide46

Non-disjunctionBZ figs pg 114Animation

Inc polyploid defSlide47

This image shows haploid (single), diploid (double), triploid (triple), and

tetraploid

(quadruple) sets of chromosomes. Triploid and

tetraploid

chromosomes are examples of polyploidy.Slide48

Inducing Non-DisjunctionDone deliberately to create new plant varietiesOften larger, more vigorous than parents

Uses seeds/seedlings soaked in colchicine / N2O* gasInhibits spindle fibre formationChromosomes fail to separate

Resulting gametes may lead to

polyploid

plants

Propagated asexually or crossed if fertile

*yes that is

nos

, nitrous oxide….Slide49

Polyploidy as a Source of Variation #1BackgroundAllo & auto

Hybrid vigour…Slide50

Polyploidy in ManukaSlide51

Don’t get confusedPolyploidyPolysomyAnueploidy?

AllopolyploidyAutopolyploidySlide52

Teosinte  Modern Corn (~1000yrs)Slide53

WheatSlide54

SpeltWhere does this fit in wheat development?Hybrid of emmer wheat

& goat grass in near east before the hexaploid bread wheat appearsSee footnotes for more…

Nb

bread wheat 8000 years ago

http://

en.wikipedia.org/wiki/Spelt

Slide55

Reproductive Isolating MechanismsNotes uploaded to weebly…Lacewing Songs:

http://www.pbs.org/wgbh/evolution/library/05/2/swf_pop/l_052_01.htmlSlide56

Evolutionary Relationships - TermsPhylogenetics: the study of evolutionary relatedness between groups of organisms. Relatedness is determined by DNA sequencing data and comparing morphological data

Phylogeny: The evolutionary development and history of a species or higher taxonomic grouping of organisms.Cladogram:

Diagram which

shows ancestral relations between

organisms

Cladistics:

method of classifying species of organisms into groups called

clades

, which consist of an ancestor organism and all its descendants (and nothing else). Slide57

CladogramsShow ancestral relations between

taxaUsing DNA analysis or morphological comparisonsSpecies are at the “leaves”Common ancestor at the “trunk”

Have an

implicit time

axis (runs forward from base to leaves) but: problems of scale, data quantity & quality

May show extinct species, but: DNA from extinct species is rareSlide58

Simplified Canid Phylogeny(shown in the cladogram below)

*The

canids

are an old lineage, separating from the other carnivores about 60 million years ago. Separation of a "wolf" branch, a "South American" branch, and a "red fox" branch occurred more recently, 7-10 million years ago.

*Mitochondrial

DNA analysis of both modern and historical specimens of red wolves failed to distinguish red them as a species separate from

gray

wolves or coyotes. They appear to be a hybrid species, and can interbreed with either

gray

wolves or coyotes.

*Two

different dates for the origin of dogs have been suggested. Mitochondrial DNA analysis suggests a date between 60-100,000 years ago -- well before the beginning of human agriculture. Other genetic and

archeological

evidence suggests a more recent date -- about 15,000 years ago. Neolithic cave drawings also show dogs hunting with humans.

*All

domestic dogs are the descendants of a few ancestral wolf stocks originating in Asia. Surprisingly this includes New World dogs, who were once thought to have been independently domesticated from New World wolves.

species

c

ommon ancestor

time

a

cladeSlide59

Molecular Phylogeny (DNA analysis) may revise past phylogenies (based on morphology)…

Hedges, S. Blair, and Poling, Laura L. A Molecular Phylogeny of Reptiles. Science, Vol. 283, No.5404, pp.998-1001The study also cast in doubt the relationship between the tuatara and

squamates

. While fewer gene sequences were available for the tuatara, six of eight comparisons showed closer affinities with

archosaurs

or turtles, while only two showed

squamates

as the closest relative. While the results of this study are not conclusive, it clearly demonstrates that we don't know all that we thought we knew about the phylogenetic relationships of living or fossil reptiles.

http://home.pcisys.net/~

dlblanc/articles/TurtlePhylogeny.php

The

Squamata

, or the

scaled reptiles

, are the largest recent order of reptiles, comprising all lizards and snakes. Slide60

Convergent EvolutionThe evolution of the same biological trait in unrelated

groups / species.Examples:Shark, icthyosaur, dolphin, penguin (a fish, reptile, mammal and bird respectively) are unrelated but have evolved a similar streamlined shape and “fins” in response to their environment (water) which provides a common selection pressure (in this case fast movement through water)

Unrelated plants have evolved water storage tissue (succulent tissues) eg Euphorbia, cacti in response to their environment (dry desert) which provides a common selection pressure (need to store water during prolonged dryness)

Analogous structures

“structures that are alike in function but have a different evolutionary origin”

Egs: wings of insects and birds; mammalian and octopus eye

Human eye vs Octopus eye

Unrelated organisms (vertebrate vs mollusc)

Developed similar eye as a result of selection pressure for well developed sight (see prey clearly, 3D)

The eye is an analogous structureSlide61

Shark

Dolphin

Penguin

Icthyosaur (2-4m)Slide62
Slide63

Convergence in PlantsThese unrelated plants have separately evolved the ability to store water in their stems.

This is a response to the natural selection pressure of dryness in the desert.The swollen stems are an example of an analogous structure

Ferocactus

pilosus

(

Mexican

lime cactus)Slide64
Slide65

Example (reading)http://blogs.discovermagazine.com/notrocketscience/2012/11/20/the-deadliest-sea-snake-is-actually-two-look-alike-species/#more-7978

http://tinyurl.com/SSSSSSSSNAKE Slide66

Divergent EvolutionWhen one ancestral group evolves into two or more species, usually in different habitats

Features:Accounts for most evolutionary changeOften due to ancestral spp. Increasing range / colonising new areas / habitats (new ecological niches) The different conditions cause different selection pressure

 different genetic pathways  genetic isolation  speciation

Alternatively:

Sequential evolution: small changes build up over time until a new species emerges (aka anagenesis, phyletic graduation)

Budding: a new species branches off while the ancestral species remain unchanged.

Cladogenesis: When a whole new group of organisms evolves (eg primates)Slide67
Slide68

Homologous Structures“The structures shared by a set of related species because they have been inherited, with or without modification, from their common

ancestor”For example, the bones that support a bat's wing are similar

in structure, type and number to

those of a human arm

.

Differences are caused by differing natural selection pressures.

Eg selection for traits enabling flight favours thin light bones in the bat.

What pressures result in the other limbs pictured?Slide69
Slide70

Homologous StructuresSlide71

http://collections.tepapa.govt.nz/exhibitions/Whales/Segment.aspx?irn=159 Slide72

Adaptive Radiation“The diversification of a group of organisms into

species filling different ecological niches”.Can occur very rapidly, usually when a large number of ecological niches are vacant.

Example

par excellence

:

Dinosaur extinction 68mya opened up many niches for exploitation (eg Brontosaurus death opened up a large browsing herbivore niche). Relatively non specialised mammals (eg

Megazostrodon

were, as adaptable ‘generalists’, able to fill these niches quickly and through

natural selection

speciate into new forms.

Note: In a discussion you MUST involve natural selection AND niche.

Eg for above example: variation in ancestral mammal species size



diet



some bigger & better able to use plants



survived better & reproduced more, passed those genes on



further selection for various traits



elephant!



Slide73

Asteroid: “Bye bye

dinos

, vacate your ecological niches!”

Mammals: “Thanks a lot for the niches, we will fill those!”Slide74

Megazostrodon

model, Natural History Museum, LondonSlide75
Slide76

Other examples:Galapagos Finches: 1 South American finch evolved into 14 spp. occupying different niches (desert, grassland…) on the Galapagos IslandsNZ Examples:

100 spp. of Hebe plants (specialised into coastal, forest, alpine… niches)

10 spp. of Powelliphanta snails (+

subspecies, over different niches)

NZ parrots (kakapo, kea, kaka) from one

ancestor 100mya

(forest vs alpine)

Note: In some of these egs radiation was very fast (many vacant niches) and involved the founder effect.

Powelliphanta

spp.Slide77

Ale – see folder

for textSlide78

Weird Mammal Groups #1Ungulates (meaning roughly "being hoofed

" or "hoofed animal") aThe odd-toed ungulates are browsing and grazing mammals, such as horses, tapirs and rhinoceroses, whose hooves each feature an odd number of

toes

Even

toed ungulates: This group includes

pigs

,

peccaries

,

hippopotamuses

,

camels

,

chevrotains

(mouse deer),

deer

,

giraffes

,

pronghorn

,

antelopes

,

sheep

,

goats

, and

cattle

.Slide79

Weird Mammal Groups #2PlacentalsEg dog, horse

MarsupialsEg wallabyMonotremesEg platypusSlide80

Hawaiian HoneycreepersHawaiian islands: volcanic origin, variety of habitats.

In absence of other bird spp. they radiated to fill numerous nichesSlide81

Galapagos Finch Niches

http://

web.visionlearning.com/custom/biology/animations/darwin_finches_working.shtml

http

://

faculty.massasoit.mass.edu/whanna/122/page4/page7/page58/page58.html

Anims

…Slide82

http

://

faculty.massasoit.mass.edu/whanna/122/page4/page7/page58/page58.html

Slide83

Co-Evolution Change in the genetic composition one species (or group) in response to the change in another.

Often occurs when close ecological interaction (symbiosis) occurs. Eg:

Between parasite &

host - exploitation

With

f

lower

shape

&

pollinator - mutualism

Between predator &

prey – exploitation

Examples:

Lions: speed, strength, co-operative hunting (to catch gazelle)

Gazelle: speed, size, strength, horns, darting behaviour (to escape lion)

An “evolutionary

arms race” one species evolves to respond to the other.

Each party exerts selection pressures on the other

 over time the spp may become mutually dependent on each other.

Relationship may become so close that extinction of one app means extinction of the other

Pollination Syndromes: where only one animal can pollinate only one specific plant (often the pollinator beak shape co-evolves with the flower shape)

Eg Adams’ mistletoe probably relied only on one NZ bird for pollination (pollinator not yet confirmed) when this birds dropped in numbers Adams mistletoe became extinct.Slide84
Slide85
Slide86

Adams MistletoeA victim of pollination syndrome?Slide87

Co-evolution example

Pseudomyrmex

ant collecting protein-rich Beltian bodies from a bullhorn acacia, Costa Rica.

This is one of the most famous mutualisms of all, the relationship between

Pseudomyrmex

ants and Acacia trees. The ants defend these small trees against herbivorous insects and vertebrates. The ants also chew away and sting any encroaching plants, clearing an area that may be up to 4 yd (4 m) in radius. In return, the plants give the ants food, such as the yellow Beltian bodies seen here, and nectar from extra-floral nectaries. The Beltian bodies contain proteins and lipids and are produced on the youngest and most delicate leaves. The plants also produce thorns that the ants hollow out for nests

.

Q. How could this evolve?Slide88

Anna's Hummingbird

(

Calypte

anna

) and bottlebrush sp

.

The needle like beak and hovering ability of a hummingbird is allows it to extract nectar (and pollinate) funnel shaped flowers or flowers with no “landing pads”Slide89

Dactylanthus taylorii

Pollinated by native bat with which it shows coevolution.

Bat:

nocturnal, blind BUT good sense of smell

Flowers:

drab, open at night, strong scent (like a bat), wide shape (for easy access)Slide90
Slide91

Punctuated Equilibrium

Evolutionary model where there are long periods of little change in a spp punctuated by short bursts of rapid change.Long periods of no evolutionary change (stasis)Stasis punctuated by short periods of evolution producing new species rapidly

Stimulus for evolution = environmental change

Species’ spend most of existence in stasis

If Correct: no transitional fossils, sudden appearance of new typesSlide92

GradualismEvolutionary model where the accumulation of changes resulting in speciation occurs slowly and steadily

Evolution proceeds slowly but continuously in response to selection pressuresEventually changes in adaptive characteristics accumulate until speciation occurs

If correct transitional forms should be seen (as is the case with horse evolution)

Example: Trilobites changed gradually over three million years

A Trilobite fossil:

Kainops invius Slide93

Trilobites…Hard-shelled, segmented creatures

lived over 520 million years ago in Earth's ancient seas.

Extinct

before dinosaurs

arrived

Key creatures

of the

Paleozoic

Era,

(1

st

era with complex life)

Fossils found in rocks in all continents

Body plan: 3 main parts – head, segmented

thorax

, and a

pygidium

(tail

piece)

Trilobite means three lobed (see right).

Huge morphological diversity in trilobites but all have this basic structure

Size: 3mm – 300mmSlide94

www.trilobites.infoSlide95

Evidence for evolutionhttp://www.sumanasinc.com/webcontent/animations/content/evolution/evolution.html Slide96

Poster TaskRest of the period to:Present an A3 colour poster on an example of convergent evolution, allopatric speciation or sympatric speciation.

You must: D

efine the type of evolution speciation

Give a captioned example (no kea, kaka, butterfly)

Explain how this example came about

Name it!Slide97

Evidence for EvolutionSlide98

1) Fossil RecordFossil = preserved impression turned into rock or mineralised remains of past organisms

Fossil record Sedimentary rock forms in layers which may contain fossils. Older strata/fossils usually found deeper (exception = after uplift).

This provides a record of:

Appearance/disappearance of species

Diversity at various times

Evidence of change of ancestral forms to modern forms

Fossil age can be determined by: dating rock layers, comparing to fossils in same strata elsewhere.

Problems:

Destruction of fossils (by subduction), some organisms

don’t fossilise well (eg soft bodied animals), most fossils are still

buried.

Archaeopteryx

represents a transitional species between reptiles and birdsSlide99

Fossil RecordSlide100

2) Comparative Anatomy“Comparison of body structures between different species”

Homologous StructuresSimilarity of structure between related species indicates evolution from a common ancestor. Eg inheritance of pentadactyl limb in different mammals

Vestigial Organs

Organs reduced in function size but remnant is shared with common ancestor or closely related species. Eg human appendix = reduced caecum, lost function of digesting cellulose, whale pelvis remnant - now no hind limbs.

How would natural selection against these structures operate?

What vestigial organs do kiwi have?

Snake

Whal

eSlide101
Slide102
Slide103

3) Biogeography“The study of geographical distribution of species”

Species on a given island may more closely resemble species on a nearby mainland rather than species on a distant island (even though the habitats may be similar).Eg Galapagos finches similar to mainland S.America finches, not similar to birds 1000s km away on Cape

V

erde islands. Adaptive radiation, allopatric speciation important here.

Absence of certain taxa can be explained by their evolution

after

a separation event.

Eg placental mammals evolved after NZ split from Australia 85mya; this explains their absence in NZ. BUT we have examples of old Gondwanan lineages eg tuatara, frogs.

Fossils of related organisms found on separate continents can be explained by continental drift.

Eg glossopteris (a fern) evolved in

G

ondwana (350-230mya). Gondwana split up into modern day Antarctica, Australia, India, Africa, S. America and fossils of it are found in all locations. It couldn’t possibly have evolved after the split up and spread to each location. Slide104

Therapods evolved in one place 140mya, spread out, continents split, therapods

left fossil remains of related species in spread apart locations. Much more plausible than a recent independent origin of each species in each location.Slide105

Biogeography

Some organisms that evolved in Gondwana have left fossils spread out amongst modern day continents. Unlikely that they could have evolved recently and spread out over the large distances involved. Eg how could the land reptile lystrosaurus get from India to Antarctica?Slide106

4) Molecular BiologyGenetic Code: this is the base sequence of DNA. Organisms which have a recent common ancestor will share more of the base sequence than those that are unrelated. If the mutation rate is known then base sequence difference between two species can be extrapolated to determine when the last common ancestor was;

Proteins: more closely related species have more similarity in their proteins (this reflects a similarity in the underlying DNA that codes for the proteins).

Hox Genes:

a group of related genes that control structure and orientation of organisms – critical for development and placing of body parts. The homeobox is a sequence within a hox gene that makes a protein that acts as a switch for the gene. The homeobox has been found to be highly conservative (changes little) across evolutionary lineages. A fly functions perfectly well with a chicken hox gene in place of its own. Slide107
Slide108

Interpretation:

The human/chimp lineage split relatively recently – there has not been enough time for mutations to cause differences in the bases of the cytochrome c gene so the amino acid sequence is identical

The human/yeast lineage split a relatively long time ago, there has been a lot of time for base differences to accumulate…Slide109

Rate of DNA hybridisationVia the process of

DNA hybridization, scientists can accurately determine the degree of relatedness between various groups of species. Matches in base sequence between species indicate a high degree of relatedness. For example, in the figure on the right you can see that more matches are made between a human and a chimp than between a human and a chicken. This indicates that the human and the chimp shared a more recent common ancestor than the human and the chicken and are closely related.Slide110

Don’t confuse the two!