Background Methods Results & Analysis C. commersonii C. commersonii C. commersonii C. hectori C. hectori C. commersonii C. commersonii La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. acutus La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. albirostris La. albirostris La. albirostris La. albirostris La. albirostris La. albirostris La. albirostris La. albirostris La. albirostris La. albirostris Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Li. borealis Unknown La. obscurus La. obscurus C. eutropia C. eutropia La. obscurus C. heavisidii La. australis La. australis La. australis La. australis La. australis La. australis La. australis La. obliquidens La. obscurus La. obscurus La. obscurus La. obscurus La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obscurus La. obscurus La. obscurus La. obliquidens La. obscurus La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obscurus La. obscurus La. obscurus La. obliquidens La. obliquidens La. obliquidens La. obliquidens La. obscurus -5 0 5 -5 0 5 10 15 Principal Component 1 Principal Component 2 -5.0 -2.5 0.0 2.5 -5 0 5 10 Principal Component 1 Principal Component 2 0 2 4 6 8 Morphometrics of the dolphin genus Lagenorhynchus: deciphering a contested phylogeny Allison Galezo 1,2 and Nicole Vollmer 1,3 1 Department of Vertebrate Zoology, Smithsonian Institution National Museum of Natural History 2 Department of Biology, Georgetown University 3 NOAA National Systematics Laboratory Recent phylogenetic studies 1-7 have indicated that the genus Lagenorhynchus, currently containing the species L. obliquidens a , L. acutus b , L. albirostris c , L. obscurus d , L. cruciger e , and L. australis f , is not monophyletic. These species were originally grouped together because of similarities in external morphology and coloration, but genetic studies have proposed that this grouping may not be valid. These studies have suggested that • L. australis and L. cruciger are sister taxa. 2-7 • L. obscurus and L. obliquidens are sister taxa. 1-7 • L. australis, L. cruciger, L. obscurus, and L. obliquidens belong in the subfamily Lissodelphininae, along with two other genera, Lissodelphis and Cephalorhynchus. 3-7 • L. acutus and L. albirostris do not belong in the same genus as the other Lagenorhynchus species, or even in the Lissodelphininae subfamily. 3-7 We sought to assess whether the skull morphology of the Lagenorhynchus species, as well as the morphology of species in Lissodelphis and Cephalorhynchus, reflected the results of these genetic studies. a b c d e f Figure 3. PCA. Principal Component 1 (PC1) explained 59.47% of the variance in the data, and was largely a measure of skull width. PC2 (19.26%) was a measure of tooth count. Note the overlap between La. obliquidens l, La. obscurus l, and La. australis l. All 5 Lagenorhynchus species lllll cluster together, and are particularly isolated from Li. borealis u and the two Cephalorhynchus clusters: pp & pp. La. acutus l and La. albirostris l lie on the margins of the Lagenorhynchus cluster. Figure 1. Phenogram from cluster analysis of dolphin skull measurements. Calculated using Euclidian distances and Ward’s method. Figure 4. PCA with size correction. All variables were regressed against condylobasal length (total skull length) to correct for size. PC1 (47.35%) was dominated by supraorbital thickness, PC2 (20.48%) by lacrimal length (Fig. 5). Note the continued overlap between La. obliquidens l and La. obscurus l, and the shift of La. australis l away from l and l and towards C. hectori p and C. commersonii p. The Lagenorhynchus and Cephalorhynchus species have formed one large super-cluster, Distance p C. commersonii (5) p C. eutropia (2) p C. heavisidii (1) p C. hectori (2) l La. acutus (24) l La. albirostris (10) l La. australis (7) l La. obliquidens (28) l La. obscurus (15) Figure 2. Species symbols key with sample sizes. u Li. borealis (11) n Unknown (1) u • Our morphological data support the hypothesis that the genus Lagenorhynchus is not monophyletic, evident from the separation in the phenogram of La. albirostris and La. acutus from the other Lagenorhynchus species, and the mix of genera in the lowermost clade (Figure 1). • Our results show that La. obscurus and La. obliquidens are very similar morphologically, which supports the hypothesis that they are closely related: they have noticeable overlap in both PCAs (Figures 3 & 4) and DFAs (not pictured) with and without a size correction, representing a wide range of skull measurements. They also cluster together in the phenogram, with the exception of 8 La. obliquidens individuals originating from a Southern Californian region believed to house a distinct La. obliquidens morphotype. 9 • The grouping of La. australis, La. obliquidens, La. obscurus, C. eutropia, and C. heavisidii in the phenogram sister to Li. borealis supports the proposed makeup of the Lissodelphininae subfamily 4-8 , but the exclusion of C. commersonii and C. hectori does not. This may be due to the exceptionally small size of C. commersonii and C. hectori. The addition of morphological data from La. cruciger is vital to clarifying the relationships within this subfamily because of the proposed close relationship between La. cruciger and La. australis 2-7 . • The close proximity/overlap of species clusters in the PCAs may be because they have been subject to similar evolutionary pressures, or due to the recent and rapid radiation of delphinids not giving these species ample time to accumulate great morphological differences. We collected 38 skull measurements from 5 of the 6 Lagenorhynchus species (excluding L. cruciger due to a lack of samples), as well as Lissodelphis borealis and all 4 Cephalorhynchus species, totaling 106 individuals. Only We would like to thank Allen Collins for introducing Ali to the world of cnidarians, as well as John Ososky, Ana Costa, Jim Mead, and Charley mature individuals were measured. Measurements were taken using the Microscribe 3D-LX. We used the Perrin 1975 8 skull measuring scheme, with the addition of 3 novel measurements. Cluster analysis (CA), principal component analysis (PCA), discriminant function analysis (DFA), and MANOVA statistical tests were run using R Version 3.2.1. Data were log transformed for analyses. When appropriate based on sample size, we tested for sexual dimorphism. We handled missing data in two ways: 1) deleting all variables and individuals with missing data, or 2) filling in missing data using averages from the same species. Overall clustering patterns were the same regardless of how missing data were treated, so method 2 was used during statistical analyses. to the exclusion of Li. borealis u. La. acutus l and La. albirostris l lie on the margins of this super-cluster. Figure 5. Lagenorhynchus skull. Supraorbital thickness (SOT) SOT and lacrimal length (LL). LL Potter for sharing their insight on marine mammals. We thank Liz Cottrell and Gene Hunt, the Natural History Research Experiences (NHRE) co- directors, as well as NHRE administrator Virginia Power, for their support and guidance. A special thanks to Gene Hunt for his assistance with the PCA. This project was made possible by the National Science Foundation. 1) Cipriano, F. (1997). Antitropical distributions and speciation in dolphins of the genus Lagenorhynchus: a preliminary analysis. Molecular Genetics of Marine Mammals Volume Special Publication, 3. 2) Miyazaki, N., & Shikano, C. (1997). Preliminary study on comparative skull morphology and vertebral formula among the six species of the genus Lagenorhynchus (Cetacea: Delphinidae). Mammalia, 61(4), 573-587. 3) LeDuc, R. G., Perrin, W. F., & Dizon, A. E. (1999). Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences. Marine Mammal Science, 15(3), 619-648. 4) Pichler, F. B., Robineau, D., Goodall, R. N. P., Meyer, M. A., Olivarria, C., & Baker, C. S. (2001). Origin and radiation of Southern Hemisphere coastal dolphins (genus Cephalorhynchus). Molecular Ecology, 10(9), 2215-2223. 5) Harlin-Cognato, A. D., & Honeycutt, R. L. (2006). Multi-locus phylogeny of dolphins in the subfamily Lissodelphininae: character synergy improves phylogenetic resolution. BMC evolutionary biology, 6(1), 87. 6) May-Collado, L., & Agnarsson, I. (2006). Cytochrome b and Bayesian inference of whale phylogeny. Molecular phylogenetics and evolution, 38(2), 344-354. 7) Banguera-Hinestroza, E., Hayano, A., Crespo, E., & Hoelzel, A. R. (2014). Delphinid systematics and biogeography with a focus on the current genus Lagenorhynchus: Multiple pathways for antitropical and trans-oceanic radiation. Molecular phylogenetics and evolution, 80, 217-230. 8) Perrin, W. F. (1975). Variation of spotted and spinner porpoise (genus Stenella) in the eastern Pacific and Hawaii. Scripps Institution of Oceanography. 9) Walker, W. A., Leatherwood, S., Goodrich, K. R., Perrin, W. F., & Stroud, R. K. (1986). Geographical variation and biology of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, in the north-eastern Pacific. Research on dolphins, 441, 465. Dolphin thumbnail images © Jörg Mazur. Background image by Steve Hillebrand. Skull image by A. Galezo.
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Background
Methods
Results & Analysis Discussion
Acknowledgments
C. commersoniiC. commersoniiC. commersonii
C. hectoriC. hectori
C. commersoniiC. commersonii
La. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostris
Li. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealis
UnknownLa. obscurusLa. obscurus
C. eutropiaC. eutropia
La. obscurusC. heavisidiiLa. australisLa. australisLa. australisLa. australisLa. australisLa. australisLa. australis
La. obliquidensLa. obscurusLa. obscurusLa. obscurusLa. obscurus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. obscurusLa. obscurusLa. obscurus
La. obliquidensLa. obscurus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. obscurusLa. obscurusLa. obscurus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. obscurus
0 2 4 6 8
Clu
ste
r De
nd
rog
ram
hclu
st (*, "w
ard
.D2
")
dis
t(data
.log
, me
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Height
-5
0
5
-5 0 5 10 15
Principal Component 1
Pri
ncip
al C
om
po
ne
nt 2
Cephalorhynchus commersonii
Cephalorhynchus eutropia
Cephalorhynchus heavisidii
Cephalorhynchus hectori
Lagenorhynchus acutus
Lagenorhynchus albirostris
Lagenorhynchus australis
Lagenorhynchus obliquidens
Lagenorhynchus obscurus
Lissodelphis borealis
Unknown
PCA
-5.0
-2.5
0.0
2.5
-5 0 5 10
Principal Component 1
Pri
ncip
al C
om
po
nen
t 2
Cephalorhynchus commersonii
Cephalorhynchus eutropia
Cephalorhynchus heavisidii
Cephalorhynchus hectori
Lagenorhynchus acutus
Lagenorhynchus albirostris
Lagenorhynchus australis
Lagenorhynchus obliquidens
Lagenorhynchus obscurus
Lissodelphis borealis
Unknown
PCA with Size Correction
C. commersoniiC. commersoniiC. commersonii
C. hectoriC. hectori
C. commersoniiC. commersonii
La. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutusLa. acutus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostrisLa. albirostris
Li. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealisLi. borealis
UnknownLa. obscurusLa. obscurus
C. eutropiaC. eutropia
La. obscurusC. heavisidiiLa. australisLa. australisLa. australisLa. australisLa. australisLa. australisLa. australis
La. obliquidensLa. obscurusLa. obscurusLa. obscurusLa. obscurus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. obscurusLa. obscurusLa. obscurus
La. obliquidensLa. obscurus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. obscurusLa. obscurusLa. obscurus
La. obliquidensLa. obliquidensLa. obliquidensLa. obliquidens
La. obscurus
0 2 4 6 8
Clu
ste
r De
nd
rog
ram
hclu
st (*, "w
ard
.D2
")
dis
t(data
.log, m
eth
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"eu
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")
Height
Morphometrics of the dolphin genus Lagenorhynchus: deciphering a contested phylogeny
Allison Galezo1,2 and Nicole Vollmer1,3
1 Department of Vertebrate Zoology, Smithsonian Institution National Museum of Natural History 2 Department of Biology, Georgetown University
3 NOAA National Systematics Laboratory
Recent phylogenetic studies1-7 have indicated that the genus Lagenorhynchus, currently containing the species L. obliquidensa , L. acutusb , L. albirostrisc , L. obscurusd , L. crucigere , and L. australisf , is not monophyletic. These species were originally grouped together because of similarities in external morphology and coloration, but genetic studies have proposed that this grouping may not be valid.
These studies have suggested that • L. australis and L. cruciger are sister taxa. 2-7
• L. obscurus and L. obliquidens are sister taxa. 1-7
• L. australis, L. cruciger, L. obscurus, and L. obliquidensbelong in the subfamily Lissodelphininae, along withtwo other genera, Lissodelphis and Cephalorhynchus. 3-7
• L. acutus and L. albirostris do not belong in the samegenus as the other Lagenorhynchus species, or even inthe Lissodelphininae subfamily. 3-7
We sought to assess whether the skull morphology of the Lagenorhynchus species, as well as the morphology of species in Lissodelphis and Cephalorhynchus, reflected the results of these genetic studies.
a b c
d e f
Figure 3. PCA. Principal Component 1 (PC1) explained 59.47% of the variance in the data, and was largely a measure of skull width. PC2 (19.26%) was a measure of tooth count. Note the overlap between La. obliquidens l, La. obscurus l, and La. australis l. All 5 Lagenorhynchus species lllll cluster together, and are particularly isolated from Li. borealis u and the two Cephalorhynchus clusters: pp & pp. La. acutus land La. albirostris l lie on the margins of the Lagenorhynchus cluster.
Figure 1. Phenogram from cluster analysis of dolphin skull measurements. Calculated using Euclidian distances and Ward’s method.
Figure 4. PCA with size correction. All variables were regressed against condylobasal length (total skull length) to correct for size. PC1 (47.35%) was dominated by supraorbital thickness, PC2 (20.48%) by lacrimal length (Fig. 5). Note the continued overlap between La. obliquidens l and La. obscurus l, and the shift of La. australis l away from l and l and towards C. hectori p and C. commersonii p. The Lagenorhynchus and Cephalorhynchus species have formed one large super-cluster,
Distance
p C. commersonii (5)
p C. eutropia (2)
p C. heavisidii (1)
p C. hectori (2)
l La. acutus (24)
l La. albirostris (10)
l La. australis (7)
l La. obliquidens (28)
l La. obscurus (15)
Figure 2. Species symbols key with sample sizes.
u Li. borealis (11)
n Unknown (1)
u
• Our morphological data support the hypothesis thatthe genus Lagenorhynchus is not monophyletic, evidentfrom the separation in the phenogram of La. albirostrisand La. acutus from the other Lagenorhynchus species,and the mix of genera in the lowermost clade (Figure 1).
• Our results show that La. obscurus and La. obliquidensare very similar morphologically, which supports thehypothesis that they are closely related: they havenoticeable overlap in both PCAs (Figures 3 & 4) and DFAs(not pictured) with and without a size correction,representing a wide range of skull measurements. Theyalso cluster together in the phenogram, with theexception of 8 La. obliquidens individuals originatingfrom a Southern Californian region believed to house adistinct La. obliquidens morphotype. 9
• The grouping of La. australis, La. obliquidens, La.obscurus, C. eutropia, and C. heavisidii in the phenogramsister to Li. borealis supports the proposed makeup ofthe Lissodelphininae subfamily4-8 , but the exclusion of C.commersonii and C. hectori does not. This may be due tothe exceptionally small size of C. commersonii and C.hectori. The addition of morphological data from La.cruciger is vital to clarifying the relationships within thissubfamily because of the proposed close relationshipbetween La. cruciger and La. australis2-7 .
• The close proximity/overlap of species clusters in thePCAs may be because they have been subject to similarevolutionary pressures, or due to the recent and rapidradiation of delphinids not giving these species ampletime to accumulate great morphological differences.
We collected 38 skull measurements from 5 of the 6 Lagenorhynchus species (excluding L. cruciger due to a lack of samples), as well as Lissodelphis borealis and all 4 Cephalorhynchus species, totaling 106 individuals. Only
We would like to thank Allen Collins for introducing Ali to the world of cnidarians, as well as John Ososky, Ana Costa, Jim Mead, and Charley
mature individuals were measured. Measurements were taken using the Microscribe 3D-LX. We used the Perrin 19758 skull measuring scheme, with the addition of 3 novel measurements.
Cluster analysis (CA), principal component analysis (PCA), discriminant function analysis (DFA), and MANOVA statistical tests were run using R Version 3.2.1. Data were log transformed for analyses. When appropriate based on sample size, we tested for sexual dimorphism. We handled missing data in two ways: 1) deleting all variables and individuals with missing data, or 2) filling in missing data using averages from the same species. Overall clustering patterns were the same regardless of how missing data were treated, so method 2 was used during statistical analyses.
to the exclusion of Li. borealis u. La. acutus l and La. albirostris l lie on the margins of this super-cluster.
Figure 5. Lagenorhynchus skull. Supraorbital thickness (SOT)
SOT
and lacrimal length (LL). LL
Potter for sharing their insight on marine mammals. We thank Liz Cottrell and Gene Hunt, the Natural History Research Experiences (NHRE) co-directors, as well as NHRE administrator Virginia Power, for their support and guidance. A special thanks to Gene Hunt for his assistance with the PCA. This project was made possible by the National Science Foundation.
1) Cipriano, F. (1997). Antitropical distributions and speciation in dolphins of the genus Lagenorhynchus: a preliminary analysis.Molecular Genetics of Marine Mammals Volume Special Publication, 3. 2) Miyazaki, N., & Shikano, C. (1997). Preliminary study on comparative skull morphology and vertebral formula among the six speciesof the genus Lagenorhynchus (Cetacea: Delphinidae). Mammalia, 61(4), 573-587. 3) LeDuc, R. G., Perrin, W. F., & Dizon, A. E. (1999). Phylogenetic relationships among the delphinid cetaceans based on full cytochromeb sequences. Marine Mammal Science, 15(3), 619-648. 4) Pichler, F. B., Robineau, D., Goodall, R. N. P., Meyer, M. A., Olivarria, C., & Baker, C. S. (2001). Origin and radiation of SouthernHemisphere coastal dolphins (genus Cephalorhynchus). Molecular Ecology, 10(9), 2215-2223. 5) Harlin-Cognato, A. D., & Honeycutt, R. L. (2006). Multi-locus phylogeny of dolphins in the subfamily Lissodelphininae: charactersynergy improves phylogenetic resolution. BMC evolutionary biology, 6(1), 87. 6) May-Collado, L., & Agnarsson, I. (2006). Cytochrome b and Bayesian inference of whale phylogeny. Molecular phylogenetics andevolution, 38(2), 344-354. 7) Banguera-Hinestroza, E., Hayano, A., Crespo, E., & Hoelzel, A. R. (2014). Delphinid systematics and biogeographywith a focus on the current genus Lagenorhynchus: Multiple pathways for antitropical and trans-oceanic radiation. Molecular phylogenetics and evolution, 80, 217-230. 8) Perrin, W. F. (1975). Variation of spotted and spinner porpoise (genus Stenella) in the eastern Pacific andHawaii. Scripps Institution of Oceanography. 9) Walker, W. A., Leatherwood, S., Goodrich, K. R., Perrin, W. F., & Stroud, R. K. (1986). Geographical variation andbiology of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, in the north-eastern Pacific. Research on dolphins, 441, 465. Dolphin thumbnail images © Jörg Mazur. Background image by Steve Hillebrand. Skull image by A. Galezo.
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