Adaptation & Natural Selection
Animal Behaviour Mark Elgar
Natural Selection 1
Outline
Darwin’s concept of natural selection Adaptations Evolution by natural selection
2
How do we define natural selection? George C. Williams (1966) Adaptation & Natural Selection. Princeton University Press
Charles Darwin
3
How do we define natural selection? George C. Williams (1966) Adaptation & Natural Selection. Princeton University Press i) The behaviour has evolved
Charles Darwin
ii) Natural selection is responsible for this evolution
3
4
Artificial selection
Dog breeds have been selected for particular traits
5
Natural selection Animals have also been bred for particular behaviours
6
A schematic of evolution Evolution = a change in the frequency of a trait within a population
Population at time t
Population at time t+1 7
A schematic of evolution Evolution = a change in the frequency of a trait within a population
Population at time t
Population at time t+10 16
Evolution by natural selection Proportional increase as a result of lower mortality or higher fecundity
Proportional decrease as a result of higher mortality or lower fecundity The trait (i.e. adaptation) determines the difference in mortality or fecundity
17
Natural selection Natural Selection: Individuals with certain traits are better adapted to their environment These individuals are more likely to survive and/or reproduce and pass their genes on to the next generation
18
Natural selection acts on behaviour
z z
Forage during day = exposure to predators
z z
Forage at night
19
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait
20
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait ii) Traits are heritable (i.e. passed on from parents to offspring)
20
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait ii) Traits are heritable (i.e. passed on from parents to offspring) iii) More individuals are born than can survive to reproduce
20
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait ii) Traits are heritable (i.e. passed on from parents to offspring)
Natural selection acts on individuals, not groups or species
iii) More individuals are born than can survive to reproduce
20
Answer: Individuals possess heritable traits. For natural selection to occur, the following criteria must be satisfied: 1) there must be natural variation in the trait (i.e. not all traits are exactly the same) 2) traits are heritable (i.e. passed from parents to offspring) 3) more individuals are born than can survive to reproduce (i.e. selection can act by preventing individuals from reproducing). Natural selection does not involve anybody actively selecting animals to reproduce. Instead, individuals with traits that are better suited for surviving and reproducing will be the ones most likely to pass on their traits to the next generation. 21
Natural selection- misconceptions
i) Short-hand expressions can be misleading
22
Natural selection- misconceptions
i) Short-hand expressions can be misleading ii) Rarely is everything perfectly adapted
22
Natural selection- misconceptions
i) Short-hand expressions can be misleading ii) Rarely is everything perfectly adapted iii) Avoid ‘just so’ stories; don’t assume something is an adaptation, test it first
22
Natural selection- misconceptions
Eyespots deter predators regardless of size, shape or number.
Artificial prey - ‘Robomoth’ - on a tree trunk is triggered by a Great tit
23
Natural selection at work Cane Toad Bufo marinus
2006
Dead juvenile carpet python 24
Natural selection at work
large head
Eat large toads with lots of poison = death
small body small head
Eat small toads with less poison = tolerate poison long body 25
Natural selection at work
Vulnerable to Bufo toxin
Red-bellied black snake
Common tree snake
Not vulnerable to Bufo toxin
Swamp snake
Keelback 26
Natural selection at work Relative head size
Mean body size 1935
Red-bellied black snakes & Common tree snakes: evolved to have longer bodies & smaller heads
2004
1935
Time since snakes first exposed to toads
2004
Swamp snakes & Keelbacks: no change in body or head size since toad introduction
27
Summary Behaviour, like any other trait, is subject to the process of natural selection Several key assumptions must be met if natural selection is to occur Take care in describing or inferring adaptations Selection is not necessarily a slow process
28
PDF-Cita%ons Slide-1 !_MG_2581!peacock!spider!Maratus!volans!by!Jurgen!O=o!(h=p://www.flickr.com/photos/59431731@N05/5521738809/).!!Reproduced!with!permission!from!Jurgen!O=o. ! Slide-3 a)!Charles!Darwin!(h=p://commons.wikimedia.org/wiki/File:Charles_Darwin_01.jpg)!By!J.!Cameron![Public!domain],!via!Wikimedia!Commons!! Slide-6 a)!"Wolf!2"!(h=p://www.flickr.com/photos/fremlin/2384478345/)!by!Robert!Dewar!(CC!BY!2.0) b)!“Great!Dane!black!laying”!(h=p://commons.wikimedia.org/wiki/File%3AGreat_Dane_black_laying.jpg)!by!Melissa!(Flickr)!(CC!BY!2.0),!via!Wikimedia!Commons c)!“Chihuahua!Dog”!(h=p://commons.wikimedia.org/wiki/File%3AChihuahua`Dog.JPG)!By!Florinux!(CC`BY`SA`3.0),!via!Wikimedia!Commons d)!“Airedale!Terrier,!stehend,!unkopiert”!(h=p://commons.wikimedia.org/wiki/File%3AAiredale_Terrier_stehend_unkupiert.JPG)!By!Musarad!![Public!domain],!via!Wikimedia!Commons! a)!“Dalmadan!dog”!(h=p://www.public`domain`image.com/fauna`animals`public`domain`images`pictures/dogs`public`domain`images`pictures/dalmadan`dog.jpg.html)!(Author!Unknown)!![Public!Domain]! b)!“Grace!The!Greyhound”!(h=ps://commons.wikimedia.org/wiki/File%3AGraceTheGreyhound.jpg)!By!Neurodoc!(CC`BY`SA`3.0),!via!Wikimedia!Commons c)!“Afghan!Hound”!(h=ps://commons.wikimedia.org/wiki/File%3AAfghan_Hound.jpg)!By!Sannse!at!the!English!language!Wikipedia!(CC`BY`SA`3.0),!via!Wikimedia!Commons d)!“A!portrait!of!a!Bulldog!named!Frank”!(h=p://commons.wikimedia.org/wiki/File%3ABulldog_portrait_Frank.jpg)!By!jjsawrey!(CC`BY`2.0),!via!Wikimedia!Commons e)!“Samoyed_600”!(h=p://commons.wikimedia.org/wiki/File:Samoyed_600.jpg)!By!Sannse!at!the!English!language!Wikipedia!(CC`BY`SA`3.0),!via!Wikimedia!Commons ! Slide-7 “Brendan!Ferris!Sheepdog!Demonstradon”!(h=p://www.youtube.com/watch?v=RIaEjCYkKAk)!by!GunGeekATX!(CC!BY!3.0) Slide-8-&-9 Evoludon!Bird!diagrams!by!Milly!Formby!(C)!University!of!Melbourne Slide-10 Birds!by!Milly!Formby!(C)!University!of!Melbourne Slide-12 a)!“An!Antechinus”!(h=p://www.flickr.com/photos/couchy/4154587035/)!by!Alan!Couch!(CC!BY!2.0) b)!!“Sun!and!Moon”!By!Milly!Formby!(C)!University!of!Melbourne c)!“Peregrine!Falcon”!(h=p://commons.wikimedia.org/wiki/File%3APeregrine_Falcon_La_Ca%C3%B1ada.jpg)!By!Juan!Lacruz!([CC`BY`SA`3.0),!via!Wikimedia!Commons Slide-13 "empty!snail!shells"!(h=p://www.flickr.com/photos/threedots/124748755/)!by!Daniel!Ullrich!(CC!BY`SA!2.0) Slide-14 "Panda!and!cub!at!San!Diego!Zoo"!(h=p://www.flickr.com/photos/supermac/4650523760/)!by!ian!mcwilliams!(CC!BY!2.0) Slide-15 "Elephant!seals!fighdng"!(h=p://en.wikipedia.org/wiki/File:Elephant_seals_fighdng.jpg)!by!Mike!Baird!(CC!BY!2.0),!via!Wikimedia!Commons 31
Slide-18 a)!“An!Antechinus”!(h=p://www.flickr.com/photos/couchy/4154587035/)!by!Alan!Couch!(CC!BY!2.0) b)!!“Sun!and!Cloud”!By!Milly!Formby!(C)!University!of!Melbourne Slide-20 “Plate!X:!White!Flamingoes,!Red!Flamingoes,!The!Skies!They!Simulate”!(h=p://commons.wikimedia.org/wiki/File%3APlate_X_White_and_Red_Flamingoes_and_The_Skies_They_Simulate_by_Thayer.jpg)!By! Abbo=!Handerson!Thayer![Public!domain],!via!Wikimedia!Commons Slide-21 a)!Peacock!bu=erfly!(Inachis!io)!(h=p://www.geograph.org.uk/photo/986930)!by!Walter!Baxter!(CC!BY!SA!2.0) b)!Wing!of!a!bu=erfly,!detail!(h=p://commons.wikimedia.org/wiki/File%3AWing_of_a_bu=erfly2.jpg)!by!Hans!Bernhard!(CC!BY!SA!30),!via!Wikimedia!Commons c)!Robomoth!with!eyespot!vs!great!dt!(h=p://www.youtube.com/watch?v=I7sxayoJMnk)!by!Sens!Ecol.!!Reproduced!with!permission!from!Mardn!Stevens. ! Slide-22 a)!"Rhinella!marina!(Linnaeus,!1758)!`!cane!toad!(4559944181)"!(h=ps://commons.wikimedia.org/wiki/File%3ARhinella_marina_%28Linnaeus%2C_1758%29_`_cane_toad_%284559944181%29.jpg)!by!Sam! Fraser`Smith!(CC!BY!2.0),!via!Wikimedia!Commons b)!"Cane!toad!distribudon!sdlls"!(h=p://commons.wikimedia.org/wiki/File%3ACane_toad_distribudon_sdlls.png)!by!"Bufoinvasion.gif:!Roke"!(CC!BY`SA!3.0),!via!Wikimedia!Commons c)!"Bufo!marinus!australian!range"!(h=p://commons.wikimedia.org/wiki/File%3ABufo_marinus_australian_range.png)!by!"Froggydarb"!(CC!BY`SA!3.0),!via!Wikimedia!Commons a)!"Juvenile!Carpet!Snake!eadng!Cane!Toad"!(h=p://commons.wikimedia.org/wiki/File%3AJuvenile_Carpet_Snake_eadng_Cane_Toad.jpg)!by!Andrew!Mercer!(CC!BY`SA!3.0),!via!Wikimedia!Commons ! Slide-23 Black!snake!and!Toad!Natural!Selecdon!diagram!by!Milly!Formby!(C)!University!of!Melbourne! Slide-24 a)!"Red`bellied!Black!Snake!(Pseudechis!porphyriacus)"!(h=p://www.flickr.com/photos/88708273@N03/8398223358/)!by!"Ma=!Clancy!Wildlife!Photography!(CC!BY!2.0) b)!"Common!Tree!Snake!Front"!(h=p://commons.wikimedia.org/wiki/File%3ACommon_Tree_Snake_Front.JPG)!by!"Quartl"!(CC!BY`SA!3.0),!via!Wikimedia!Commons c)!"Black`bellied!Swamp!Snake!(Hemiaspis!signata)!III"!!(h=p://commons.wikimedia.org/wiki/File%3ABlack`bellied_Swamp_Snake_%28Hemiaspis_signata%29_III.jpg)!by!Doug!Beckers!(CC!BY`SA!2.0),!via! Wikimedia!Commons d)!"Keelback!eadng!a!Dahl's!Aquadc!Frog"!(h=p://www.flickr.com/photos/88708273@N03/8692590510/)!by!Ma=!Clancy!Wildlife!Photography!(CC!BY!2.0) ! Slide-25 Graphs!by!Mark!Elgar!based!on!data!sourced!from!Phillips,!B!and!Shine!R!(2004)!Adapdng!to!an!invasive!species:!Toxic!cane!toads!induce!morphological!change!in!Australian!Snakes.!Proceedings+of+the+Na1onal+ Academy+of+Sciences+of+the+United+States+of+America.!Vol.-101,-No.-49-pp-17150-–-17155
32
Natural Selection 1
Outline
Darwin’s concept of natural selection Adaptations Evolution by natural selection
2
How do we define natural selection? George C. Williams (1966) Adaptation & Natural Selection. Princeton University Press
Charles Darwin
3
How do we define natural selection? George C. Williams (1966) Adaptation & Natural Selection. Princeton University Press i) The behaviour has evolved
Charles Darwin
ii) Natural selection is responsible for this evolution
3
4
Artificial selection
Dog breeds have been selected for particular traits
5
Natural selection Animals have also been bred for particular behaviours
6
A schematic of evolution Evolution = a change in the frequency of a trait within a population
Population at time t
Population at time t+1 7
A schematic of evolution Evolution = a change in the frequency of a trait within a population
Population at time t
Population at time t+10 16
Evolution by natural selection Proportional increase as a result of lower mortality or higher fecundity
Proportional decrease as a result of higher mortality or lower fecundity The trait (i.e. adaptation) determines the difference in mortality or fecundity
17
Natural selection Natural Selection: Individuals with certain traits are better adapted to their environment These individuals are more likely to survive and/or reproduce and pass their genes on to the next generation
18
Natural selection acts on behaviour
z z
Forage during day = exposure to predators
z z
Forage at night
19
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait
20
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait ii) Traits are heritable (i.e. passed on from parents to offspring)
20
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait ii) Traits are heritable (i.e. passed on from parents to offspring) iii) More individuals are born than can survive to reproduce
20
Natural selection For natural selection to occur, three requirements must be satisfied: i) Natural variation in the trait ii) Traits are heritable (i.e. passed on from parents to offspring)
Natural selection acts on individuals, not groups or species
iii) More individuals are born than can survive to reproduce
20
Answer: Individuals possess heritable traits. For natural selection to occur, the following criteria must be satisfied: 1) there must be natural variation in the trait (i.e. not all traits are exactly the same) 2) traits are heritable (i.e. passed from parents to offspring) 3) more individuals are born than can survive to reproduce (i.e. selection can act by preventing individuals from reproducing). Natural selection does not involve anybody actively selecting animals to reproduce. Instead, individuals with traits that are better suited for surviving and reproducing will be the ones most likely to pass on their traits to the next generation. 21
Natural selection- misconceptions
i) Short-hand expressions can be misleading
22
Natural selection- misconceptions
i) Short-hand expressions can be misleading ii) Rarely is everything perfectly adapted
22
Natural selection- misconceptions
i) Short-hand expressions can be misleading ii) Rarely is everything perfectly adapted iii) Avoid ‘just so’ stories; don’t assume something is an adaptation, test it first
22
Natural selection- misconceptions
Eyespots deter predators regardless of size, shape or number.
Artificial prey - ‘Robomoth’ - on a tree trunk is triggered by a Great tit
23
Natural selection at work Cane Toad Bufo marinus
2006
Dead juvenile carpet python 24
Natural selection at work
large head
Eat large toads with lots of poison = death
small body small head
Eat small toads with less poison = tolerate poison long body 25
Natural selection at work
Vulnerable to Bufo toxin
Red-bellied black snake
Common tree snake
Not vulnerable to Bufo toxin
Swamp snake
Keelback 26
Natural selection at work Relative head size
Mean body size 1935
Red-bellied black snakes & Common tree snakes: evolved to have longer bodies & smaller heads
2004
1935
Time since snakes first exposed to toads
2004
Swamp snakes & Keelbacks: no change in body or head size since toad introduction
27
Summary Behaviour, like any other trait, is subject to the process of natural selection Several key assumptions must be met if natural selection is to occur Take care in describing or inferring adaptations Selection is not necessarily a slow process
28
PDF-Cita%ons Slide-1 !_MG_2581!peacock!spider!Maratus!volans!by!Jurgen!O=o!(h=p://www.flickr.com/photos/59431731@N05/5521738809/).!!Reproduced!with!permission!from!Jurgen!O=o. ! Slide-3 a)!Charles!Darwin!(h=p://commons.wikimedia.org/wiki/File:Charles_Darwin_01.jpg)!By!J.!Cameron![Public!domain],!via!Wikimedia!Commons!! Slide-6 a)!"Wolf!2"!(h=p://www.flickr.com/photos/fremlin/2384478345/)!by!Robert!Dewar!(CC!BY!2.0) b)!“Great!Dane!black!laying”!(h=p://commons.wikimedia.org/wiki/File%3AGreat_Dane_black_laying.jpg)!by!Melissa!(Flickr)!(CC!BY!2.0),!via!Wikimedia!Commons c)!“Chihuahua!Dog”!(h=p://commons.wikimedia.org/wiki/File%3AChihuahua`Dog.JPG)!By!Florinux!(CC`BY`SA`3.0),!via!Wikimedia!Commons d)!“Airedale!Terrier,!stehend,!unkopiert”!(h=p://commons.wikimedia.org/wiki/File%3AAiredale_Terrier_stehend_unkupiert.JPG)!By!Musarad!![Public!domain],!via!Wikimedia!Commons! a)!“Dalmadan!dog”!(h=p://www.public`domain`image.com/fauna`animals`public`domain`images`pictures/dogs`public`domain`images`pictures/dalmadan`dog.jpg.html)!(Author!Unknown)!![Public!Domain]! b)!“Grace!The!Greyhound”!(h=ps://commons.wikimedia.org/wiki/File%3AGraceTheGreyhound.jpg)!By!Neurodoc!(CC`BY`SA`3.0),!via!Wikimedia!Commons c)!“Afghan!Hound”!(h=ps://commons.wikimedia.org/wiki/File%3AAfghan_Hound.jpg)!By!Sannse!at!the!English!language!Wikipedia!(CC`BY`SA`3.0),!via!Wikimedia!Commons d)!“A!portrait!of!a!Bulldog!named!Frank”!(h=p://commons.wikimedia.org/wiki/File%3ABulldog_portrait_Frank.jpg)!By!jjsawrey!(CC`BY`2.0),!via!Wikimedia!Commons e)!“Samoyed_600”!(h=p://commons.wikimedia.org/wiki/File:Samoyed_600.jpg)!By!Sannse!at!the!English!language!Wikipedia!(CC`BY`SA`3.0),!via!Wikimedia!Commons ! Slide-7 “Brendan!Ferris!Sheepdog!Demonstradon”!(h=p://www.youtube.com/watch?v=RIaEjCYkKAk)!by!GunGeekATX!(CC!BY!3.0) Slide-8-&-9 Evoludon!Bird!diagrams!by!Milly!Formby!(C)!University!of!Melbourne Slide-10 Birds!by!Milly!Formby!(C)!University!of!Melbourne Slide-12 a)!“An!Antechinus”!(h=p://www.flickr.com/photos/couchy/4154587035/)!by!Alan!Couch!(CC!BY!2.0) b)!!“Sun!and!Moon”!By!Milly!Formby!(C)!University!of!Melbourne c)!“Peregrine!Falcon”!(h=p://commons.wikimedia.org/wiki/File%3APeregrine_Falcon_La_Ca%C3%B1ada.jpg)!By!Juan!Lacruz!([CC`BY`SA`3.0),!via!Wikimedia!Commons Slide-13 "empty!snail!shells"!(h=p://www.flickr.com/photos/threedots/124748755/)!by!Daniel!Ullrich!(CC!BY`SA!2.0) Slide-14 "Panda!and!cub!at!San!Diego!Zoo"!(h=p://www.flickr.com/photos/supermac/4650523760/)!by!ian!mcwilliams!(CC!BY!2.0) Slide-15 "Elephant!seals!fighdng"!(h=p://en.wikipedia.org/wiki/File:Elephant_seals_fighdng.jpg)!by!Mike!Baird!(CC!BY!2.0),!via!Wikimedia!Commons 31
Slide-18 a)!“An!Antechinus”!(h=p://www.flickr.com/photos/couchy/4154587035/)!by!Alan!Couch!(CC!BY!2.0) b)!!“Sun!and!Cloud”!By!Milly!Formby!(C)!University!of!Melbourne Slide-20 “Plate!X:!White!Flamingoes,!Red!Flamingoes,!The!Skies!They!Simulate”!(h=p://commons.wikimedia.org/wiki/File%3APlate_X_White_and_Red_Flamingoes_and_The_Skies_They_Simulate_by_Thayer.jpg)!By! Abbo=!Handerson!Thayer![Public!domain],!via!Wikimedia!Commons Slide-21 a)!Peacock!bu=erfly!(Inachis!io)!(h=p://www.geograph.org.uk/photo/986930)!by!Walter!Baxter!(CC!BY!SA!2.0) b)!Wing!of!a!bu=erfly,!detail!(h=p://commons.wikimedia.org/wiki/File%3AWing_of_a_bu=erfly2.jpg)!by!Hans!Bernhard!(CC!BY!SA!30),!via!Wikimedia!Commons c)!Robomoth!with!eyespot!vs!great!dt!(h=p://www.youtube.com/watch?v=I7sxayoJMnk)!by!Sens!Ecol.!!Reproduced!with!permission!from!Mardn!Stevens. ! Slide-22 a)!"Rhinella!marina!(Linnaeus,!1758)!`!cane!toad!(4559944181)"!(h=ps://commons.wikimedia.org/wiki/File%3ARhinella_marina_%28Linnaeus%2C_1758%29_`_cane_toad_%284559944181%29.jpg)!by!Sam! Fraser`Smith!(CC!BY!2.0),!via!Wikimedia!Commons b)!"Cane!toad!distribudon!sdlls"!(h=p://commons.wikimedia.org/wiki/File%3ACane_toad_distribudon_sdlls.png)!by!"Bufoinvasion.gif:!Roke"!(CC!BY`SA!3.0),!via!Wikimedia!Commons c)!"Bufo!marinus!australian!range"!(h=p://commons.wikimedia.org/wiki/File%3ABufo_marinus_australian_range.png)!by!"Froggydarb"!(CC!BY`SA!3.0),!via!Wikimedia!Commons a)!"Juvenile!Carpet!Snake!eadng!Cane!Toad"!(h=p://commons.wikimedia.org/wiki/File%3AJuvenile_Carpet_Snake_eadng_Cane_Toad.jpg)!by!Andrew!Mercer!(CC!BY`SA!3.0),!via!Wikimedia!Commons ! Slide-23 Black!snake!and!Toad!Natural!Selecdon!diagram!by!Milly!Formby!(C)!University!of!Melbourne! Slide-24 a)!"Red`bellied!Black!Snake!(Pseudechis!porphyriacus)"!(h=p://www.flickr.com/photos/88708273@N03/8398223358/)!by!"Ma=!Clancy!Wildlife!Photography!(CC!BY!2.0) b)!"Common!Tree!Snake!Front"!(h=p://commons.wikimedia.org/wiki/File%3ACommon_Tree_Snake_Front.JPG)!by!"Quartl"!(CC!BY`SA!3.0),!via!Wikimedia!Commons c)!"Black`bellied!Swamp!Snake!(Hemiaspis!signata)!III"!!(h=p://commons.wikimedia.org/wiki/File%3ABlack`bellied_Swamp_Snake_%28Hemiaspis_signata%29_III.jpg)!by!Doug!Beckers!(CC!BY`SA!2.0),!via! Wikimedia!Commons d)!"Keelback!eadng!a!Dahl's!Aquadc!Frog"!(h=p://www.flickr.com/photos/88708273@N03/8692590510/)!by!Ma=!Clancy!Wildlife!Photography!(CC!BY!2.0) ! Slide-25 Graphs!by!Mark!Elgar!based!on!data!sourced!from!Phillips,!B!and!Shine!R!(2004)!Adapdng!to!an!invasive!species:!Toxic!cane!toads!induce!morphological!change!in!Australian!Snakes.!Proceedings+of+the+Na1onal+ Academy+of+Sciences+of+the+United+States+of+America.!Vol.-101,-No.-49-pp-17150-–-17155
32
