Geographic Isolation and Speciation of the Atlantic red-lipped blenny and the Pacific fanged blenny.

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Geographic Isolation and Speciation of the
Atlantic red-lipped blenny and the Pacific fanged
blenny.

• Caitlyn Roan, Tara Connor, and John Grimsley

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The Blenny Ophioblennius

• One of the most diverse suborders of teleost
  fishes
• 723 species
• 127 genera
• 6 families

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The Blenny Ophioblennius

• Family Blenniidae
• Algivorous fish
• Inhabit shallow, rocky shores and reefs
• Typical reef fish life history
• Benthic eggs that hatch after 5 days
• Long, planktonic larval phase of approx. 50 days

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The Blenny Ophioblennius

• This species lives on the Caribbean side of the
  Panama Isthmus

• This species lives on the Pacific side of the
  Panama Isthmus

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The Blenny Ophioblennius

• O. steindachneri divided into 2 subspecies
• O. s. steindachneri (1)
• O. s. clippertonensis (2)
• O. atlanticus divided into 2 subspecies
• O. a. atlanticus (3)
• O. a. macclurei (4)

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Question 1

• When did the Panama Isthmus form and was it the
  actual cause of separation of the two species of
  blennies?

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The Panama Isthmus

• Commonly used in evolutionary studies to evaluate
  morphological, ecological, and molecular
  divergences
• Rose 3.1 MYA
• Vicariance hypothesis (Rosen)
• Dispersal hypothesis (Briggs)
• Ancestral species, Ophioblennius, separated 7 MYA
  during initial shoaling

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The Panama Isthmus
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The Atlantic Redlipped Blenny

• Ophioblennius atlanticus macclurei

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The Pacific Fanged Blenny

• Ophioblennius steindachneri clippertonensis

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Question 2

• What are the different biogeographic regions and
  does the presence of an oceanographic barrier
  (Panama Isthmus) influence speciation of the
  blennies?

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Pacific VS Atlantic Oceans

• Pacific

• Atlantic

• Reefs widely scattered
• Closed ocean basin
• Stable currents
• Islands provided stepping stones in range
  expansion
• Low rates of gene flow

• Reefs continuous along coastline
• Open ocean basin
• Unstable currents
• High rates of gene flow

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Biogeographic RegionsStudy by Muss et al.
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A study by Muss et al.

• 177 individuals from 10 Atlantic 4 Pacific
  locations
• Segments of mitochondrial DNA cytochrome b gene
  were obtained
• Genetic variation estimated from haplotype
  diversities nucleotide diversities

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A study by Muss et al.

• Sequence comparisons revealed 176 variable sites
  with 272 transitions and 39 transversions, a
  total of 122 haplotypes in 171 individuals
• To compare populations an exact test of
  population differentiation was conducted using
  haplotypes defined by transversion-differences
  only
• The 39 observed transversions defined 25
  haplotypes, including from one to five
  transversion haplotypes per location

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A study by Muss et al.
Locations
Haplotypes
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A study by Muss et al.
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Conclusions

• O. atlanticus O. steindachneri shared common
  ancestor 7 MYA
• The 2 species of blenny were separated before
  closure of the Panama Isthmus
• After the closure, an oceanographic barrier,
  biogeographic provinces, and natural factors
  influenced speciation
• Populations in close proximity to one another
  show higher levels of gene flow and lower levels
  of population differentiation
• Populations closer to one another are more
  similar

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Further Research

• Obtain samples of Ophioblennius atlanticus
  Ophioblennius steindachneri from each of the
  different biogeographic regions and place them in
  tanks to see if they will mate with one another

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Sources

• Muss, A, D.R. Robertson, C.A. Stepien, P Wirtz,
  and B.W. Bowen. "Phylogeography of opioblennius
  
• the role of ocean currents and geography in
  reef fish evolution." Society for the Study of
  Evolution 55.3 (2001) 561-572. Web. 13 Apr
  2010. lthttps//illiad.radford.edu/illiad.dll?Acti
  on10F orm75Value264074gt.
• Springer, V.G. 1962. A review of the Blenniid
  fishes of the genus Ophioblennius Gill. Copeia
  1962426-433.