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Phylogenetic and morphologic analyses of a coastal fish reveals a marine biogeographic break of terrestrial origin in the southern Caribbean.

Betancur-R R, Acero P A, Duque-Caro H, Santos SR - PLoS ONE (2010)

Bottom Line: The estimated approximately 0.86 my divergence of the lineages from a common ancestor coincides with the timing of the SMM displacement at approximately 0.78 my.Results presented here support the hypothesis that organismal properties as well as extrinsic factors lead to diversification of the Cathorops mapale group along the northern coast of South America.Comparative examination of additional Southern Caribbean taxa, particularly those with varying life history traits and dispersal capabilities, will determine the extent by which the SMM has influenced marine phylogeography in the region.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Auburn University, Auburn, Alabama, USA. betanri@gmail.com

ABSTRACT

Background: Marine allopatric speciation involves interplay between intrinsic organismal properties and extrinsic factors. However, the relative contribution of each depends on the taxon under study and its geographic context. Utilizing sea catfishes in the Cathorops mapale species group, this study tests the hypothesis that both reproductive strategies conferring limited dispersal opportunities and an apparent geomorphologic barrier in the Southern Caribbean have promoted speciation in this group from a little studied area of the world.

Methodology/principal findings: Mitochondrial gene sequences were obtained from representatives of the Cathorops mapale species group across its distributional range from Colombia to Venezuela. Morphometric and meristic analyses were also done to assess morphologic variation. Along a approximately 2000 km transect, two major lineages, Cathorops sp. and C. mapale, were identified by levels of genetic differentiation, phylogenetic reconstructions, and morphological analyses. The lineages are separated by approximately 150 km at the Santa Marta Massif (SMM) in Colombia. The northward displacement of the SMM into the Caribbean in the early Pleistocene altered the geomorphology of the continental margin, ultimately disrupting the natural habitat of C. mapale. The estimated approximately 0.86 my divergence of the lineages from a common ancestor coincides with the timing of the SMM displacement at approximately 0.78 my.

Main conclusions/significance: Results presented here support the hypothesis that organismal properties as well as extrinsic factors lead to diversification of the Cathorops mapale group along the northern coast of South America. While a lack of pelagic larval stages and ecological specialization are forces impacting this process, the identification of the SMM as contributing to allopatric speciation in marine organisms adds to the list of recognized barriers in the Caribbean. Comparative examination of additional Southern Caribbean taxa, particularly those with varying life history traits and dispersal capabilities, will determine the extent by which the SMM has influenced marine phylogeography in the region.

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Related in: MedlinePlus

Principal component analysis of 35 morphometric variables from the Cathorops mapale group.Scatterplots of (A) PC2 vs. PC3 and (B) PC2 vs. PC4 (percent of variation for each PC given in parenthesis). Opened and filled symbols represent males and females, respectively.
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pone-0011566-g003: Principal component analysis of 35 morphometric variables from the Cathorops mapale group.Scatterplots of (A) PC2 vs. PC3 and (B) PC2 vs. PC4 (percent of variation for each PC given in parenthesis). Opened and filled symbols represent males and females, respectively.

Mentions: In the PC analysis, PC1, PC2, PC3, and PC4 explained 87.59%, 4.10%, 2.68%, and 1.50% of the variation, respectively. While PC1 is the size factor, the remaining components represent size-free shape variation [39]. Scatterplots of PC2 vs. PC3 and PC2 vs. PC4 revealed morphometric overlap for Cathorops sp. and C. mapale (Fig. 3). Similar results were obtained after removing 18 morphometric variables (see Text S2) potentially associated with sexual dimorphism in Cathorops (results not shown, [21], [40]). Furthermore, males and females overlapped in all analyses, suggesting morphometric variation is not mainly driven by sexual differentiation. Despite the observed overlap in the multivariate analyses, Cathorops sp. and C. mapale were separated by the averages of a morphometric ratio and the modes of two meristic variables (although some overlap occurs). The bivariate plot of maxillary barbel vs. posterior internarial distance was the best morphometric discriminator (Fig. 4; maxillary barbel/posterior internarial distance: 4.8–7.9, mean 6.1± SD 0.8 in C. mapale; 3.6–6.0, mean 4.4± SD 0.8 in Cathorops sp.). For the meristic analyses, anterior rakers on first (20–24, mode 23, in C. mapale; 16–21, mode 18, in Cathorops sp.) and second (20–24, mode 23, in C. mapale; 16–21, mode 18, in Cathorops sp.) gill arches were the best variables differentiating the two lineages (see details in Table 2).


Phylogenetic and morphologic analyses of a coastal fish reveals a marine biogeographic break of terrestrial origin in the southern Caribbean.

Betancur-R R, Acero P A, Duque-Caro H, Santos SR - PLoS ONE (2010)

Principal component analysis of 35 morphometric variables from the Cathorops mapale group.Scatterplots of (A) PC2 vs. PC3 and (B) PC2 vs. PC4 (percent of variation for each PC given in parenthesis). Opened and filled symbols represent males and females, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2903491&req=5

pone-0011566-g003: Principal component analysis of 35 morphometric variables from the Cathorops mapale group.Scatterplots of (A) PC2 vs. PC3 and (B) PC2 vs. PC4 (percent of variation for each PC given in parenthesis). Opened and filled symbols represent males and females, respectively.
Mentions: In the PC analysis, PC1, PC2, PC3, and PC4 explained 87.59%, 4.10%, 2.68%, and 1.50% of the variation, respectively. While PC1 is the size factor, the remaining components represent size-free shape variation [39]. Scatterplots of PC2 vs. PC3 and PC2 vs. PC4 revealed morphometric overlap for Cathorops sp. and C. mapale (Fig. 3). Similar results were obtained after removing 18 morphometric variables (see Text S2) potentially associated with sexual dimorphism in Cathorops (results not shown, [21], [40]). Furthermore, males and females overlapped in all analyses, suggesting morphometric variation is not mainly driven by sexual differentiation. Despite the observed overlap in the multivariate analyses, Cathorops sp. and C. mapale were separated by the averages of a morphometric ratio and the modes of two meristic variables (although some overlap occurs). The bivariate plot of maxillary barbel vs. posterior internarial distance was the best morphometric discriminator (Fig. 4; maxillary barbel/posterior internarial distance: 4.8–7.9, mean 6.1± SD 0.8 in C. mapale; 3.6–6.0, mean 4.4± SD 0.8 in Cathorops sp.). For the meristic analyses, anterior rakers on first (20–24, mode 23, in C. mapale; 16–21, mode 18, in Cathorops sp.) and second (20–24, mode 23, in C. mapale; 16–21, mode 18, in Cathorops sp.) gill arches were the best variables differentiating the two lineages (see details in Table 2).

Bottom Line: The estimated approximately 0.86 my divergence of the lineages from a common ancestor coincides with the timing of the SMM displacement at approximately 0.78 my.Results presented here support the hypothesis that organismal properties as well as extrinsic factors lead to diversification of the Cathorops mapale group along the northern coast of South America.Comparative examination of additional Southern Caribbean taxa, particularly those with varying life history traits and dispersal capabilities, will determine the extent by which the SMM has influenced marine phylogeography in the region.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Auburn University, Auburn, Alabama, USA. betanri@gmail.com

ABSTRACT

Background: Marine allopatric speciation involves interplay between intrinsic organismal properties and extrinsic factors. However, the relative contribution of each depends on the taxon under study and its geographic context. Utilizing sea catfishes in the Cathorops mapale species group, this study tests the hypothesis that both reproductive strategies conferring limited dispersal opportunities and an apparent geomorphologic barrier in the Southern Caribbean have promoted speciation in this group from a little studied area of the world.

Methodology/principal findings: Mitochondrial gene sequences were obtained from representatives of the Cathorops mapale species group across its distributional range from Colombia to Venezuela. Morphometric and meristic analyses were also done to assess morphologic variation. Along a approximately 2000 km transect, two major lineages, Cathorops sp. and C. mapale, were identified by levels of genetic differentiation, phylogenetic reconstructions, and morphological analyses. The lineages are separated by approximately 150 km at the Santa Marta Massif (SMM) in Colombia. The northward displacement of the SMM into the Caribbean in the early Pleistocene altered the geomorphology of the continental margin, ultimately disrupting the natural habitat of C. mapale. The estimated approximately 0.86 my divergence of the lineages from a common ancestor coincides with the timing of the SMM displacement at approximately 0.78 my.

Main conclusions/significance: Results presented here support the hypothesis that organismal properties as well as extrinsic factors lead to diversification of the Cathorops mapale group along the northern coast of South America. While a lack of pelagic larval stages and ecological specialization are forces impacting this process, the identification of the SMM as contributing to allopatric speciation in marine organisms adds to the list of recognized barriers in the Caribbean. Comparative examination of additional Southern Caribbean taxa, particularly those with varying life history traits and dispersal capabilities, will determine the extent by which the SMM has influenced marine phylogeography in the region.

Show MeSH
Related in: MedlinePlus