Caitlyn Roan, Tara Connor, and John Grimsley

The Blenny: Ophioblennius One of the most diverse suborders of teleost fishes 723 species 127 genera 6 families

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

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

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)

Question 1 When did the Panama Isthmus form and was it the actual cause of separation of the two species of blennies?

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

The Panama Isthmus

The Atlantic Redlipped Blenny Ophioblennius atlanticus & macclurei

The Pacific Fanged Blenny Ophioblennius steindachneri & clippertonensis

Question 2 What are the different biogeographic regions and does the presence of an oceanographic barrier (Panama Isthmus) influence speciation of the blennies?

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

Biogeographic Regions: Study by Muss et al.

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

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

A study by Muss et al. Haplotypes Locations

A study by Muss et al.

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

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

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): Web. 13 Apr Springer, V.G A review of the Blenniid fishes of the genus Ophioblennius Gill. Copeia 1962: