Transcript Eurythoe complanata

Eurythoe complanata: more cryptic species in the Pacific?
Mirandia Johnson, Elizabeth Borda and Anja Schulze
Department of Marine Biology, Texas A&M University at Galveston
Undergraduate
RESULTS AND DISCUSSION
ABSTRACT
Mitochondrial DNA data has shown that Eurythoe complanata is a cryptic
species complex characterized by deeply divergent sympatric populations
in the Atlantic and on either side of Panama, despite almost no
morphological differences. Previous work examined populations primarily
in the Caribbean and Atlantic Ocean, with little exploration of the
phylogenetic relationships of Pacific populations. We aim to study these
relationships using mitochondrial (COI and 16S rDNA) sequence data and
include representatives from populations in the east Pacific (Mexico and
the Gulf of California), Indo-Pacific (Indonesia, Moorea, and American
Samoa), and from aquaria. The objectives of this study are to: 1) identify if
there are cryptic species in the Pacific; 2) infer the phylogenetic
relationships among amphi-Pacific populations; and 3) estimate the
distributional patterns of animals that reproduce both sexually and
asexually.
Table 1. Average K2P corrected (blue; above diagonal) and uncorrected (green,
below diagonal) COI pairwise distances (PD). A. Average interspecific and corrected
intraspecific (along diagonal) PD. B. Average PD among Eurythoe representatives
from select geographic regions.
TABLE A
INTRODUCTION
Cryptic species
•Cryptic species are morphologically similar species classified as a single
species . Morphology alone may severely underestimate the number of
species (Nygren and Pleijel. 2010).
•A lack of defining characteristics has been correlated to wide geographic
distributions (Barroso, et al. 2010).
Eurythoe
•Eurythoe is represented by the circumtropical species, Eurythoe
complanata, which exhibits low morphological variation (Figure 3) across
geographically disjunct populations (Barroso, et al. 2010).
•Barroso, et al. (2010) examined the morphology of over 200 samples from:
the coast of Brazil; South Atlantic islands; Panama(Bocas del Toro, Taboga);
Gold Coast and east coast of Africa; Red Sea; Sri Lanka; and the Azores. They
found no clear morphological differences to distinguish these populations,
but found molecular evidence for the existence of cryptic species.
•Eurythoe complanata can reproduce sexually and asexually (e.g.
fragmentation and regeneration), but little is known about their planktonic
larval stages (Reish and Pernet, 2009)
Figure 1. Map showing the worldwide distribution of samples included in this study.
•
2
3
4
5
6
7
1. E. complanata
0.3%
15.3%
21.7%
23.1%
20.6%
27.3%
27.2%
2. E. “mexicana”
12.4%
0.5%
24.7%
25.8%
27.6%
27.8%
27.8%
3. Eurythoe Pacific (A)
16.2%
17.9%
--
12.3%
14.2%
18.6%
21.2%
4. Eurythoe Pacific (B)
16.8%
18.4%
10%
--
8.7%
22.4%
22.3%
5. Eurythoe Pacific (C)
15.5%
19.2%
11.1%
7.4%
1.7%
22.1%
22.0%
6. Eurythoe Pacific (D)
18.9%
19.3%
14.4%
16.5%
16.3%
--
1.8%
7. Eurythoe Pacific (E)
18.8%
19.2%
15.9%
16.5%
16.3%
1.7%
0.4%
TABLE B
1
2
3
4
5
6
7
8
9
10
A
Samoa
B
Sula
C
Sula
C
Suma
D
GoC
D
Gue
E
Aq. SL
E
Aq. Ger.
E
BT
E
Suma
--
12.3%
14.2%
13.4%
18.6%
18.6%
21.6%
21.0%
20.8%
21.1%
2. B (Sulawesi)
10.0%
--
7.6%
10.3%
22.4%
22.4%
23.0%
22.3%
22.1%
21.8%
3. C (Sulawesi)
11.3%
6.9%
--
22.2%
22.7%
22.1%
21.9%
21.6%
4. C (Sumatra)
10.7%
8.6%
2.1%
--
21.2%
21.2%
21.7%
21.1%
20.9%
20.6%
5. D (Gulf of Cali)
14.4%
16.5%
16.5%
15.8%
--
0.0%
2.1%
1.4%
1.4%
1.8%
6. D (Guerrero)
14.4%
16.5%
16.5%
15.8%
0.0%
--
2.1%
1.4%
1.4%
1.8%
7. E (Aq. St. Louis)
16.2%
16.8%
16.8%
16.2%
2.1%
2.1%
--
0.7%
0.3%
0.3%
8. E (Aq. Germany)
15.8%
16.5%
16.5%
15.8%
1.4%
1.4%
0.7%
--
0.0%
0.3%
9. E (Bocas del Toro)
15.8%
16.5%
16.5%
15.8%
1.5%
1.5%
0.5%
0.2%
--
0.0%
10. E (Sumatra)
16.0%
16.3%
16.3%
15.6%
1.9%
1.9%
0.5%
0.5%
0.3%
--
1. A (Samoa)
QUESTIONS AND OBJECTIVES
•
•
1
Are there cryptic Eurythoe species in the Pacific?
What are the phylogenetic relationships among populations on opposite
sides of the Pacific Ocean?
To provide a phylogenetic molecular framework for characterizing
species diversity in the genus Eurythoe, in the absence of unambiguous
morphological characters.
1.8%
22.2%
Figure 3. Eurythoe specimen showing
typical caruncle (B) and brachial
filaments (C).
METHODS
Sampling
•29 Samples were included in this study representing: the Pacific coast of
Mexico (n=10), Gulf of California (GoC; n=2), Yucatan Peninsula (n=2),
Caribbean coast of Panama (n=2), Sumatra, Indonesia (n=4), Sulawesi,
Indonesia (n=4), American Samoa (n=1), Moorea (n=2), and from marine
aquaria in St. Louis, MO (n=1) and Osnabrück, Germany (n=1). We also
included representatives of E. complanata (n=5) from the Caribbean and E.
complanata var. mexicana from GoC (n=6).
Amplification and Sequencing
•Mitochondrial 16S rDNA and cytochrome c oxidase subunit 1 genes were
amplified and sequenced using standard protocols.
•Sequences were edited in Sequencher v.4.10.1 and aligned using Muscle
(www.ebi.ac.uk/Tools/msa/muscle)
Phylogenetic Analysis
•Inter- and intraspecific COI pairwise genetic distances were calculated using
Mega 5: uncorrected and corrected with the K2P model of evolution.
•Phylogenetic relationships were estimated under parsimony and maximum
likelihood assumptions. Parsimony analyzed with PAUP* and run with 1000
parsimony jackknife support values. Maximum likelihood analyses were run
using RaxMLGUI with thorough bootstrap ( 10 reps; 1000 pseudo replicates).
Highlights
•The phylogeny supports the presence of at least five cryptic species in the Pacific. (Figure 2A;
Table 1)
•Several clade representatives (B, C, and E) have broad geographic distributions, possibly assisted
by anthropogenic means and asexual reproductive modes (e.g. aquarium live rock).
•Clade I appears to have west Pacific origins, possibly with recent introduction to the east Pacific.
•Clade II is the most widespread, found in: Indonesia, the Yucatan peninsula, GoC, and western
coast of Mexico Caribbean side of Panama, and aquariums in Germany and Missouri.
•High inter-clade genetic distances support distinct species.
•Low intra-clade genetic distances were found among representatives from disjunct geographic
locations.
Future Studies
•Continue collecting nuclear ITS sequence data, as an independent line of genetic evidence to
corroborate mitochondrial results.
•Increase diversity by naming new species and revising old ones.
Acknowledgements
This project is funded by NSF ATOL grant DEB 1036186 . Images: G. Rouse, C. Sanchez
References
Barroso, R., M. Klautau, A. M. Sole-Cava, and P.C. Paiva (2010). "Eurythoe complanata (Polychaeta: Amphinomidae), the
'cosmopolitan' fireworm, consists of at least three cryptic species." Marine Biology 157(1): 69-80.
Nygren, A., Pleijel, F. (2010) From one to ten in a single stroke – resolving the European Eumida sanguinea (Phyllodocidae,
Annelida) species complex. Molecular Phylogenetics and Evolution 58(1): 132-141.
Reish, D, and B Pernet. (2009) "Annelid Life Cycle Cultures." Annelids in Modern Biology. Ed. Daniel H. Shain. Hoboken, NJ:
Wiley-Blackwell. 47-62.