Happy face spidersofhawaii

HAWAII 2009: Happy-FacedHAWAII 2009: Happy-Faced
Spiders, Insects of Hawaii,Spiders, Insects of Hawaii,
andand
“Javametrics”“Javametrics”
Presented byPresented by
Dr. Sean D. PuckettDr. Sean D. Puckett
Dr. Maureen MurphyDr. Maureen Murphy

HAWAII 2009: “HIJ” of HHAWAII 2009: “HIJ” of Hawaiiawaii
Please get used to this scene. Once you flyPlease get used to this scene. Once you fly
away from the U.S. coast, heading to Hawaii,away from the U.S. coast, heading to Hawaii,
this is what you see out the airplane windowthis is what you see out the airplane window
for 2500 miles.for 2500 miles.

HAPPY-FACE SPIDERSHAPPY-FACE SPIDERS

 The happy-face spider exhibits an array of color patterns on the backThe happy-face spider exhibits an array of color patterns on the back
of its abdomen, sometimes resembles a smiling face. These spidersof its abdomen, sometimes resembles a smiling face. These spiders
blend in with the undersides of leaves where they build their flimsyblend in with the undersides of leaves where they build their flimsy
webs and catch prey.webs and catch prey.
 The happy-face spider isThe happy-face spider is endemicendemic to the Hawaiianto the Hawaiian archipelagoarchipelago but isbut is
only found on four of the islands: Oahu, Molokai, Maui, and Hawaii.only found on four of the islands: Oahu, Molokai, Maui, and Hawaii.
The spider populations on these four islands show off a variety ofThe spider populations on these four islands show off a variety of
happy-face patterns.happy-face patterns. Such a variation in form isSuch a variation in form is
referred to as a polymorphism — manyreferred to as a polymorphism — many
forms (also known as morphs).forms (also known as morphs).

 Different smiles, single speciesDifferent smiles, single species
 Despite the variation in colors (and underlyingDespite the variation in colors (and underlying
gene versions), all of the happy-face spiders:gene versions), all of the happy-face spiders:
have the same anatomical features,have the same anatomical features,
interact in the same ways with their environmentinteract in the same ways with their environment
and with other organisms,and with other organisms,
share the same reproductive behaviors andshare the same reproductive behaviors and
methods of catching insect prey, andmethods of catching insect prey, and
freely mate with one another.freely mate with one another.

For these reasons, researchers consider
happy-face spiders to be one species,
even though individuals have different
color patterns.
Intrigued by their variation, Drs.
Rosemary Gillespie, Geoff Oxford, and
Bruce Tabashnik, all then working at the
University of Hawaii, set out to study the
morphology, ecology, and behavior of
these spiders. Let's follow their
investigation as they learn more about the
evolution of "smiling."

A MYSTERIOUS RATIO onA MYSTERIOUS RATIO on
the Island of Mauithe Island of Maui

WHY?WHY?
The "other" patterns included plain red, plainThe "other" patterns included plain red, plain
white, red smiles, and red frowns. Therewhite, red smiles, and red frowns. There
was no consistency within the occurrence ofwas no consistency within the occurrence of
the "other" patterns, but the two yellow tothe "other" patterns, but the two yellow to
one "other" occurred generation afterone "other" occurred generation after
generation. The researchers always foundgeneration. The researchers always found
about two yellow morphs for every one non-about two yellow morphs for every one non-
yellow morph.yellow morph.

How about on the other islands?How about on the other islands?
When Gillespie and Oxford went on to studyWhen Gillespie and Oxford went on to study
the happy-face spiders on the other islands,the happy-face spiders on the other islands,
they were surprised by their results. Notthey were surprised by their results. Not
only did each island harbor the same sortsonly did each island harbor the same sorts
of morphs, but the different morphs alsoof morphs, but the different morphs also
occurred at almost exactly the sameoccurred at almost exactly the same
frequency in each population. Just as infrequency in each population. Just as in
Maui, the frequency of yellow morph spidersMaui, the frequency of yellow morph spiders
to those with other patterns was 2:1.to those with other patterns was 2:1.

Is this surprising?Is this surprising?
 Why is that so surprising? Well, if you rolled a pairWhy is that so surprising? Well, if you rolled a pair
of dice and got a two and a one you wouldn't beof dice and got a two and a one you wouldn't be
surprised. But if you rolled the same dice againsurprised. But if you rolled the same dice again
and got a two and a one, and again and got a twoand got a two and a one, and again and got a two
and a one, and again and got a two and a one,and a one, and again and got a two and a one,
you'd start to wonder what was going on! Gillespieyou'd start to wonder what was going on! Gillespie
and Oxford were similarly surprised. Why were theand Oxford were similarly surprised. Why were the
same color patterns found at the same frequencysame color patterns found at the same frequency
on each of the four islands? What was going on?on each of the four islands? What was going on?

MARVIN GAYE: “What’s Goin’MARVIN GAYE: “What’s Goin’
On?”On?”
Listen to Marvin and think aboutListen to Marvin and think about
the happy-face spidersthe happy-face spiders

Exploring the Color-PatternExploring the Color-Pattern
Frequency on the IslandsFrequency on the Islands
Why did each island have a 2:1 ratio of yellow toWhy did each island have a 2:1 ratio of yellow to
other morphs? A first hypothesis involvedother morphs? A first hypothesis involved
dispersal. As an example, imagine that we startdispersal. As an example, imagine that we start
out with two populations with different ratios ofout with two populations with different ratios of
blue to orange individuals. One population is halfblue to orange individuals. One population is half
blue spiders and half orange, and the other isblue spiders and half orange, and the other is
heavily biased towards orange individuals. Whatheavily biased towards orange individuals. What
would happen to the populations if there were nowould happen to the populations if there were no
movement between them, in other words, if theremovement between them, in other words, if there
were no dispersal?were no dispersal?

What happens?What happens?
The ratios in each population changeThe ratios in each population change
independently and remain quite differentindependently and remain quite different
from each other. But what would happen iffrom each other. But what would happen if
individuals were allowed toindividuals were allowed to move betweenmove between
populations, in other words, if dispersalpopulations, in other words, if dispersal
between populations were common?between populations were common?
http://evolution.berkeley.edu/evolibrary/article/_0_0/happyface_05http://evolution.berkeley.edu/evolibrary/article/_0_0/happyface_05

The Happy Face Spider “Dispersal”The Happy Face Spider “Dispersal”
TheoryTheory
 Because some genes are being exchangedBecause some genes are being exchanged
every generation, each population ends upevery generation, each population ends up
with the same ratio of blue to orange!with the same ratio of blue to orange!
Gillespie and Oxford thought that thisGillespie and Oxford thought that this
mechanism might explain the consistent 2:1mechanism might explain the consistent 2:1
ratio they found among the happy-faceratio they found among the happy-face
spiders. They based a first hypothesis onspiders. They based a first hypothesis on
this idea.this idea.

DISPERSAL HYPOTHESISDISPERSAL HYPOTHESIS
Dispersal of spiders between islandsDispersal of spiders between islands
has caused a consistent ratio ofhas caused a consistent ratio of 22
yellowyellow: 1 "other": 1 "other" on all four islands.on all four islands.

Molecular Data to the RescueMolecular Data to the Rescue
 Gillespie and Oxford turned to molecularGillespie and Oxford turned to molecular
data to test this hypothesis.data to test this hypothesis.
 Two types of molecular data used:Two types of molecular data used:
PROTEIN DATA andPROTEIN DATA and
DNADNA

DATA SET #1:ProteinsDATA SET #1:Proteins
 Individuals normally vary in the exact structure ofIndividuals normally vary in the exact structure of
their proteins, a set of molecules essential to alltheir proteins, a set of molecules essential to all
living things. You and your mom, for example,living things. You and your mom, for example,
might carry Version A of a particular protein, whilemight carry Version A of a particular protein, while
your cousin carries Version B of that protein.your cousin carries Version B of that protein.
Furthermore, different populations have differentFurthermore, different populations have different
protein versions and different frequencies of theseprotein versions and different frequencies of these
versions. So perhaps in Thailand, there are sixversions. So perhaps in Thailand, there are six
common versions of the protein (a high variationcommon versions of the protein (a high variation
population), but in Peru, only one protein versionpopulation), but in Peru, only one protein version
is common (a low variation population).is common (a low variation population).

DATA SET #1:Evaluating theDATA SET #1:Evaluating the
Evidence from Proteins in theEvidence from Proteins in the
Happy-Face SpidersHappy-Face Spiders
 Evaluating the evidence from proteinsEvaluating the evidence from proteins
The scientists' study of proteins in theThe scientists' study of proteins in the
happy-face spiders revealed that differenthappy-face spiders revealed that different
islands had very different levels of variation.islands had very different levels of variation.
This suggests that dispersal between theThis suggests that dispersal between the
islands is not very common.islands is not very common.

DATA SET #2: DNADATA SET #2: DNA
 DNA is a molecule that carries genetic informationDNA is a molecule that carries genetic information
from generation to generation in the form of afrom generation to generation in the form of a
code. By comparing differences in the code'scode. By comparing differences in the code's
sequence between individuals, it is possible tosequence between individuals, it is possible to
determine "who is more closely related to whom"determine "who is more closely related to whom"
— in general, the more similar the DNA— in general, the more similar the DNA
sequences, the more closely related any twosequences, the more closely related any two
individuals or populations are and the less timeindividuals or populations are and the less time
they have been isolated. Gillespie and Oxfordthey have been isolated. Gillespie and Oxford
sampled DNA from different morphs on differentsampled DNA from different morphs on different
islands and compared their sequences.islands and compared their sequences.

Evaluating the DNA EvidenceEvaluating the DNA Evidence
 The DNA evidence suggested that the spiderThe DNA evidence suggested that the spider
populations were related as this tree shows. All ofpopulations were related as this tree shows. All of
the color morphs in one island population arethe color morphs in one island population are
more closely related to each other than they are tomore closely related to each other than they are to
the color morphs from populations on otherthe color morphs from populations on other
islands. For example, yellow morphs from aislands. For example, yellow morphs from a
population on Hawaii are almost identical in DNApopulation on Hawaii are almost identical in DNA
sequence to red front morphs from the samesequence to red front morphs from the same
island, but are quite different from a yellow morphisland, but are quite different from a yellow morph
on Maui or Oahu.on Maui or Oahu.


And the Tree shows??And the Tree shows??
 All of the color morphs in one islandAll of the color morphs in one island
population are more closely related to eachpopulation are more closely related to each
other than they are to the color morphs fromother than they are to the color morphs from
populations on other islands. For example,populations on other islands. For example,
yellow morphs from a population on Hawaiiyellow morphs from a population on Hawaii
are almost identical in DNA sequence to redare almost identical in DNA sequence to red
front morphs from the same island, but arefront morphs from the same island, but are
quite different from a yellow morph on Mauiquite different from a yellow morph on Maui
or Oahu.or Oahu.

The Tree Suggests…The Tree Suggests…
 The tree suggests that the populations ofThe tree suggests that the populations of
spiders on different islands have beenspiders on different islands have been
isolated from one another — in other words,isolated from one another — in other words,
that dispersal between islands is not verythat dispersal between islands is not very
common. After all, if dispersal betweencommon. After all, if dispersal between
islands were common, we would expect toislands were common, we would expect to
find some spiders on Maui that were morefind some spiders on Maui that were more
closely related to some spiders on Hawaiiclosely related to some spiders on Hawaii
than to other spiders on Maui.than to other spiders on Maui.

What do YOU think the Protein andWhat do YOU think the Protein and
DNA evidence say about theDNA evidence say about the
“DISPERSAL” hypothesis?“DISPERSAL” hypothesis?
 Well, both lines of evidence point to the sameWell, both lines of evidence point to the same
answer: dispersal is not common, so the Dispersalanswer: dispersal is not common, so the Dispersal
Hypothesis is probably not a good one.Hypothesis is probably not a good one.
 Gillespie and her colleagues needed to come upGillespie and her colleagues needed to come up
with an alternative hypothesis to explain thewith an alternative hypothesis to explain the
mysterious 2:1 ratio — but meanwhile, theymysterious 2:1 ratio — but meanwhile, they
noticed something striking about the tree they hadnoticed something striking about the tree they had
produced.produced.

Do you notice anything STRIKINGDo you notice anything STRIKING
about the Tree and the ORDER ofabout the Tree and the ORDER of
the Islands?the Islands?

A SURPRISE!A SURPRISE!
 The physical order of the islands and the tree's branchingThe physical order of the islands and the tree's branching
pattern match up! That's a bit like drawing numbers out ofpattern match up! That's a bit like drawing numbers out of
a hat one at a time and getting the numbers 1 through 4 ina hat one at a time and getting the numbers 1 through 4 in
the exact correct order — it might happen by chance, butthe exact correct order — it might happen by chance, but
not very often. Is this correspondence between islandnot very often. Is this correspondence between island
geography and the evolutionary tree a coincidence, or isgeography and the evolutionary tree a coincidence, or is
there some other explanation?there some other explanation?
 The correspondence is not a coincidence, but in order toThe correspondence is not a coincidence, but in order to
understand why, you need to know a little bit about theunderstand why, you need to know a little bit about the
formation of these islands. The islands in the Hawaiianformation of these islands. The islands in the Hawaiian
archipelago are arranged linearly from oldest to youngest.archipelago are arranged linearly from oldest to youngest.
Kauai is the oldest island, Oahu the next oldest, and theKauai is the oldest island, Oahu the next oldest, and the
large island of Hawaii is the youngest.large island of Hawaii is the youngest.

Age of the Hawaiian IslandsAge of the Hawaiian Islands

EVOLUTIONARY TREEEVOLUTIONARY TREE
SUGGESTSSUGGESTS
 The evolutionary tree suggests that the "oldest" (original) group ofThe evolutionary tree suggests that the "oldest" (original) group of
spiders evolved on the oldest island of Oahu.spiders evolved on the oldest island of Oahu.
 As new islands formed, individuals from this original populationAs new islands formed, individuals from this original population
colonized subsequent islands in a "hopscotch" manner. The youngestcolonized subsequent islands in a "hopscotch" manner. The youngest
islands of Maui and Hawaii were colonized last and harbor theislands of Maui and Hawaii were colonized last and harbor the
"youngest" populations of spiders."youngest" populations of spiders.
 TO SEE THIS IN ACTION, GO TO:TO SEE THIS IN ACTION, GO TO:
 http://evolution.berkeley.edu/evolibrary/article/_0_0/happyface_07http://evolution.berkeley.edu/evolibrary/article/_0_0/happyface_07

STUDYING GENES: More MysterySTUDYING GENES: More Mystery
 Now Gillespie and her colleagues understood aNow Gillespie and her colleagues understood a
little more about the evolutionary history of thelittle more about the evolutionary history of the
happy-face spiders, but they still didn't understandhappy-face spiders, but they still didn't understand
the 2:1 ratio. The proteins and DNA sequencesthe 2:1 ratio. The proteins and DNA sequences
together demonstrated that very few spiderstogether demonstrated that very few spiders
moved between populations on different islands.moved between populations on different islands.
This ruled out dispersal as an explanation for theThis ruled out dispersal as an explanation for the
similar morphs and morph frequencies on differentsimilar morphs and morph frequencies on different
islands. What else might explain the consistentislands. What else might explain the consistent
ratio? Perhaps learning more about the genetics ofratio? Perhaps learning more about the genetics of
these happy-face patterns would revealthese happy-face patterns would reveal
something.something.

HAPPY-FACE SPIDER GENETICSHAPPY-FACE SPIDER GENETICS
 Gillespie and Oxford turned to breeding experiments to identify theGillespie and Oxford turned to breeding experiments to identify the
genetic mechanism behind color pattern formation.genetic mechanism behind color pattern formation.
 They started with spiders from Maui, bred individuals of knownThey started with spiders from Maui, bred individuals of known
parentage, and counted the number of offspring of each morph. Thisparentage, and counted the number of offspring of each morph. This
type of breeding experiment is a common method used to figure outtype of breeding experiment is a common method used to figure out
how genes produce a particular trait such as color morphhow genes produce a particular trait such as color morph
 Selective breeding between individuals of known parentage shouldSelective breeding between individuals of known parentage should
result in predictable patterns of color morphs in the offspring. And inresult in predictable patterns of color morphs in the offspring. And in
fact, that was the case for the Maui spiders. The frequency of colorfact, that was the case for the Maui spiders. The frequency of color
patterns in both male and female offspring was consistent with whatpatterns in both male and female offspring was consistent with what
you would expect if color pattern were passed from parent to offspringyou would expect if color pattern were passed from parent to offspring
at a single gene on a chromosome.at a single gene on a chromosome.

GENETICS on MAUIGENETICS on MAUI

On the Big Island (HAWAII), thingsOn the Big Island (HAWAII), things
were different!were different!

GENETICS on HAWAIIGENETICS on HAWAII
 On HawaiiOn Hawaii, when a yellow female is mated with a, when a yellow female is mated with a
"red front" male, the cross produces 50% yellow"red front" male, the cross produces 50% yellow
females, 0 yellow males, 0 red front females, andfemales, 0 yellow males, 0 red front females, and
50% red front males. These results are typical of50% red front males. These results are typical of
this cross.this cross.
 The genetic mechanisms were different betweenThe genetic mechanisms were different between
the spider populations on Maui and Hawaii. Thethe spider populations on Maui and Hawaii. The
spider populations had evolved the same colorspider populations had evolved the same color
patterns and the same color pattern frequencies,patterns and the same color pattern frequencies,
but they'd done it in totally different ways! Why didbut they'd done it in totally different ways! Why did
all the islands independently evolve the same setall the islands independently evolve the same set
of color pattern traits?of color pattern traits?

Does SEXUAL SELECTION haveDoes SEXUAL SELECTION have
anything to do with it?anything to do with it?
 Listen to Marvin Gaye’s “SexualListen to Marvin Gaye’s “Sexual
Healing” and think about SEXUALHealing” and think about SEXUAL
SELECTION and the HAPPY-SELECTION and the HAPPY-
FACE SPIDERS….FACE SPIDERS….

STRANGERS in the NIGHT…STRANGERS in the NIGHT…
 Gillespie and Oxford also rejected thisGillespie and Oxford also rejected this
hypothesis based on two pieces ofhypothesis based on two pieces of
evidence: (1) the spiders cannot see color,evidence: (1) the spiders cannot see color,
and (2) they are nocturnal. Color blindand (2) they are nocturnal. Color blind
spiders finding each other in the dark arespiders finding each other in the dark are
unlikely to choose a mate based on aunlikely to choose a mate based on a
smiling red abdomen! So sexual selectionsmiling red abdomen! So sexual selection
probably doesn't have much to do with it.probably doesn't have much to do with it.

Does it pay to mate blind andDoes it pay to mate blind and
nocturnal?nocturnal?

THE PREDATOR-SEARCHTHE PREDATOR-SEARCH
HYpothesisHYpothesis
 Based upon research with blue jays.Based upon research with blue jays.
 Gillespie and colleagues currently hypothesize thatGillespie and colleagues currently hypothesize that
predators searching for happy-face spiders maintain thepredators searching for happy-face spiders maintain the
2:1 ratio on the islands. On each island, predators are2:1 ratio on the islands. On each island, predators are
efficiently searching for the most common morph, theefficiently searching for the most common morph, the
yellow morph, or inefficiently searching for several morphs.yellow morph, or inefficiently searching for several morphs.
This gives an advantage to non-yellow morphs, since theyThis gives an advantage to non-yellow morphs, since they
escape predation more often. But anytime other morphsescape predation more often. But anytime other morphs
get very common, predators start looking for them instead,get very common, predators start looking for them instead,
which drives their frequencies back down. This mechanismwhich drives their frequencies back down. This mechanism
could help explain why each island has evolved a variety ofcould help explain why each island has evolved a variety of
morphs and why we consistently observe a 2:1 ratio ofmorphs and why we consistently observe a 2:1 ratio of
yellow to other spiders.yellow to other spiders.

TIME FOR ATIME FOR A HAPPY-FACE SPIDERHAPPY-FACE SPIDER
CUPCAKE!CUPCAKE!
 It’s Hawaiian cocktail time (pineapple juice/It’s Hawaiian cocktail time (pineapple juice/
Kona coffee, snacks) to mingle and meetKona coffee, snacks) to mingle and meet
your classmates and hear some authenticyour classmates and hear some authentic
Hawaiian music….return in about 15Hawaiian music….return in about 15
minutes for Kona Coffee and Hawaiianminutes for Kona Coffee and Hawaiian
Javametrics!Javametrics!

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