← Exit
  1. Watch
  2. Word of the day
  3. Predict
  4. Read the paper
  5. Exit ticket

Finding Nemo’s Clownfish, College

Video 1. Finding Nemo got the clownfish wrong

Clownfish live in groups inside an anemone, and the biggest fish is the female. When the female is gone, the biggest male turns into a female. So after Nemo’s mom was gone, Marlin would have become the mom.

Video 2. Nemo is probably not Marlin’s son

Clownfish parents guard their eggs until the eggs hatch. Then the babies drift in open water for about a week and a half and usually settle in a different anemone. Scientists used DNA from clownfish on 310 anemones to build a family tree, and relatives shared an anemone only about 2% of the time.

A common clownfish in the tentacles of a sea anemone
A tadpole is the larva of a frog or toad. Video 2 uses the plural, larvae.

Your word of the day is

LAHR-vuh

larvaghost, maskfrom Latin larva

A young animal that hatches from an egg and looks far different from the adult it will become.

Two clownfish in a purple sea anemone on a reef in Palau

Océane Salles and the Kimbe Island team put together a family tree of 2,927 clownfish, then counted the parents and offspring living in the same anemone. Make a guess before you read the paper, and write one sentence on why you think so.

What percent of parent-and-offspring pairs in the Kimbe Island family tree do you predict shared an anemone?

Hint

In video 2, Raven gives a figure for relatives in general. Would parents and offspring share an anemone more often or less often than relatives in general?

Two clownfish on a sea anemone

Read the paper

Salles and others, “First genealogy for a wild marine fish population reveals multigenerational philopatry,” PNAS, 2016. The paper is free to read.

Divers on Océane Salles’s team sampled the orange clownfish on Kimbe Island in Papua New Guinea, home to 310 anemones, six times between 2003 and 2013. The team read 22 DNA markers from each fin clip and reconstructed a family tree of 2,927 fish. Table 1 of the paper counts the family links in that tree, then counts the related pairs living in the same anemone.

RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
A group of clownfish swimming together

Table 1 lists 987 maternal and 987 paternal parent-and-offspring links, and 9 of those pairs shared an anemone.

About ____ of parent-and-offspring links in Table 1 shared an anemone.

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
A two-banded clownfish in a sea anemone

Among Table 1 rows with hundreds of family links, which relationship shared an anemone most often?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
Fish swimming over a coral reef

Grand cousins top Table 1 at 5.9%, from 1 related pair out of 17 links.

How much weight should the 5.9% for grand cousins in Table 1 carry?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
Clownfish swimming in and out of the tentacles of a sea anemone on a coral reef

Generations overlap on Kimbe Island, so the team rejected every match to a single parent.

What error does rejecting single-parent matches prevent in the Kimbe Island family tree?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
Two clownfish sharing a sea anemone, darting among its tentacles

What do the Kimbe Island team’s strict matching rules cost the counts in Table 1?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
A clownfish swimming through the waving tentacles of its anemone home

On Kimbe Island, self-recruitment averaged 56%, yet the inbreeding coefficient was only 0.018.

Why did inbreeding stay rare among Kimbe Island clownfish?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
Several clownfish crowded together in one sea anemone

What would you predict for Kimbe Island clownfish if fewer larvae arrived from other reefs?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
The camera tilts across a coral reef full of corals and small fish

On Kimbe Island, 56% of settlers hatched locally, and 44% arrived as larvae from other reefs.

Which recommendation to a reef manager do the Kimbe Island numbers back best?

See the table
RelationshipFamily links in the treeRelated pairs in the same anemonePercent in the same anemone
Parent and offspring987 maternal + 987 paternal9
Full siblings1,80924, including 1 inbred mating
Maternal half siblings4122
Paternal half siblings2485
Paternal grandparent and grandchild278 grandmother + 278 grandfather3, including 1 inbred mating
Uncle or aunt and nephew or niece30810
Half uncle or half aunt and nephew or niece1652
Cousins2181
Grand cousins171
Scuba divers gliding over a coral reef

Table 1 of the Salles paper counts the family links in the Kimbe Island family tree and the related pairs that shared an anemone.

What does Table 1 of the Salles paper show about Kimbe Island relatives?

Blue-green ocean water rippling at the surface

Which question can’t Table 1 of the Salles paper answer?

Clownfish swimming among sea anemone tentacles on a reef in Bali

Lesson complete

Today’s word

larva

LAHR-vuh

An immature, free-living form of an animal that changes into a different adult form through metamorphosis.

Back to the lessonStart over
Up nextparthenogenetic chimaeraBlood XX, skin XY
Sources
  1. Océane Salles, Benoit Pujol, Serge Planes and seven co-authors, led from the Université de Perpignan Via Domitia in France, PNAS, 2016
  2. Madison Pacaro, Tina Barbasch, Michaela Rogers, Juan Chavez, Peter Buston and John Majoris, Boston University, Ethology, 2023
  3. Peter Buston, Steven Bogdanowicz, Alex Wong and Richard Harrison, Molecular Ecology, 2007
  4. Peter Buston, Proceedings of the Royal Society B, 2004
  5. Theresa Rueger, Peter Buston and colleagues at Boston University and James Cook University, Proceedings of the Royal Society B, 2018
  6. Laura Casas, Xabier Irigoien and colleagues at King Abdullah University of Science and Technology in Saudi Arabia, Scientific Reports, 2016
  7. John Pearce, The Auk, 2007
  8. Vision and Change core concepts and competencies, as summarized in Brownell and others, CBE Life Sciences Education, 2014
  9. Word origins from Dictionary.com: larva, Lares, larvicide, philo-, patri-, proto-, proton, andro-, protandrous
  10. Spanish and French spellings from Wiktionary
  11. Instagram originals of video 1 and video 2, not linked because Instagram needs a login