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Mitochondrial DNA variation, but not nuclear DNA, sharply divides morphologically identical chameleons along an ancient geographic barrier.

Bar Yaacov D, Arbel-Thau K, Zilka Y, Ovadia O, Bouskila A, Mishmar D - PLoS ONE (2012)

Bottom Line: AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates.Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST.We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

ABSTRACT
The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel) into two subspecies, Chamaeleo chamaeleon recticrista (CCR) and C. c. musae (CCM). CCR mostly inhabits the Mediterranean climate (northern Israel), while CCM inhabits the sands of the north-western Negev Desert (southern Israel). AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097), consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA) fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year old marine barrier at the Jezreel Valley exactly where the mtDNA clusters meet. We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits.

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Results of a canonical discriminant function analysis of the morphological data set, demonstrating the separation between the desert (C. c. musae) and Mediterranean (C. c. recticrista) subspecies.The first canonical variate (score 1 = CV1), which provides the maximal separation among instars, is given by: CV1 = 0.345×logA×0.834×logB−0.013×logD−0.03×logE+0.257×logF+0.121×logG−0.91×logH+0.371×logI−0.45×logJ−1.49×logK+0.354×logL−1.043×logM−0.609×logN+0.83×logO (see Table S1, Fig. S1).
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pone-0031372-g002: Results of a canonical discriminant function analysis of the morphological data set, demonstrating the separation between the desert (C. c. musae) and Mediterranean (C. c. recticrista) subspecies.The first canonical variate (score 1 = CV1), which provides the maximal separation among instars, is given by: CV1 = 0.345×logA×0.834×logB−0.013×logD−0.03×logE+0.257×logF+0.121×logG−0.91×logH+0.371×logI−0.45×logJ−1.49×logK+0.354×logL−1.043×logM−0.609×logN+0.83×logO (see Table S1, Fig. S1).

Mentions: In order to assess patterns of morphological variation in chameleons in Israel, we performed multivariate analysis of variance (MANOVA) followed by a canonical discriminant function analysis (see Materials and Methods) of 14 morphological traits in a sample of 147 chameleons (Tables S1, S2). These chameleons were collected in 7 geographic regions, i.e., Nizzanim sand dunes in the southern Coastal Plain, the western Negev Desert, Jerusalem Mountains area, Carmel Mountain area, Haifa Bay area, Jezreel Valley, and several sites in northern Israel (including the Golan Heights, Upper and Lower Galilee, Kinnert area, Bet-Shean Valley and the Gilboa) (Fig. 1). The results of this analysis supported the former classification into two subspecies, Chamaelo-chamaeleon recticristae (CCR) and Chamaelo-chamaeleon musae (CCM) [13], as well as their geographical distribution in Israel (Fig. 2). Six morphological characters were sufficient to distinguish the CCR and CCM subspecies: crest–mouth length, crest length, arm length, medial foot pad length, medial hand pad length and eye diameter (Table S2). It is important to note that although the Nizzanim sand dunes appear to be a very similar habitat to the sands of the north-western Negev, all of the collected chameleons in Nizzanim sand dunes grouped within the CCR cluster rather than the CCM cluster. Using Principal Component Analysis (PCA), we found that PC1 and PC2 accounted for 78.84% and 8.64%, respectively, of the total variance between the CCR and CCM subspecies (Fig. 2, Fig. S1). All of the loadings of the components in PC1 were positive, and therefore this axis is interpreted as representing overall body size. Some of the PC2 loadings were positive and some negative so this axis was interpreted as representing variation in shape that was independent of body size. Even though the subspecies were separated on PC1, indicating a smaller body size of CCM compared to CCR, it was clear that the large morphological differentiation occurred along the PC2 axis. PCA performed only with head morphology or only the limb morphology showed no clear clustering, indicating that indeed it was the ratio between the head and the limb (shape) that distinguished the two subspecies. It is important to note that these size and shape differences between the two subspecies were not confounded by sexual dimorphism in size or shape (Fig. S1).


Mitochondrial DNA variation, but not nuclear DNA, sharply divides morphologically identical chameleons along an ancient geographic barrier.

Bar Yaacov D, Arbel-Thau K, Zilka Y, Ovadia O, Bouskila A, Mishmar D - PLoS ONE (2012)

Results of a canonical discriminant function analysis of the morphological data set, demonstrating the separation between the desert (C. c. musae) and Mediterranean (C. c. recticrista) subspecies.The first canonical variate (score 1 = CV1), which provides the maximal separation among instars, is given by: CV1 = 0.345×logA×0.834×logB−0.013×logD−0.03×logE+0.257×logF+0.121×logG−0.91×logH+0.371×logI−0.45×logJ−1.49×logK+0.354×logL−1.043×logM−0.609×logN+0.83×logO (see Table S1, Fig. S1).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3306244&req=5

pone-0031372-g002: Results of a canonical discriminant function analysis of the morphological data set, demonstrating the separation between the desert (C. c. musae) and Mediterranean (C. c. recticrista) subspecies.The first canonical variate (score 1 = CV1), which provides the maximal separation among instars, is given by: CV1 = 0.345×logA×0.834×logB−0.013×logD−0.03×logE+0.257×logF+0.121×logG−0.91×logH+0.371×logI−0.45×logJ−1.49×logK+0.354×logL−1.043×logM−0.609×logN+0.83×logO (see Table S1, Fig. S1).
Mentions: In order to assess patterns of morphological variation in chameleons in Israel, we performed multivariate analysis of variance (MANOVA) followed by a canonical discriminant function analysis (see Materials and Methods) of 14 morphological traits in a sample of 147 chameleons (Tables S1, S2). These chameleons were collected in 7 geographic regions, i.e., Nizzanim sand dunes in the southern Coastal Plain, the western Negev Desert, Jerusalem Mountains area, Carmel Mountain area, Haifa Bay area, Jezreel Valley, and several sites in northern Israel (including the Golan Heights, Upper and Lower Galilee, Kinnert area, Bet-Shean Valley and the Gilboa) (Fig. 1). The results of this analysis supported the former classification into two subspecies, Chamaelo-chamaeleon recticristae (CCR) and Chamaelo-chamaeleon musae (CCM) [13], as well as their geographical distribution in Israel (Fig. 2). Six morphological characters were sufficient to distinguish the CCR and CCM subspecies: crest–mouth length, crest length, arm length, medial foot pad length, medial hand pad length and eye diameter (Table S2). It is important to note that although the Nizzanim sand dunes appear to be a very similar habitat to the sands of the north-western Negev, all of the collected chameleons in Nizzanim sand dunes grouped within the CCR cluster rather than the CCM cluster. Using Principal Component Analysis (PCA), we found that PC1 and PC2 accounted for 78.84% and 8.64%, respectively, of the total variance between the CCR and CCM subspecies (Fig. 2, Fig. S1). All of the loadings of the components in PC1 were positive, and therefore this axis is interpreted as representing overall body size. Some of the PC2 loadings were positive and some negative so this axis was interpreted as representing variation in shape that was independent of body size. Even though the subspecies were separated on PC1, indicating a smaller body size of CCM compared to CCR, it was clear that the large morphological differentiation occurred along the PC2 axis. PCA performed only with head morphology or only the limb morphology showed no clear clustering, indicating that indeed it was the ratio between the head and the limb (shape) that distinguished the two subspecies. It is important to note that these size and shape differences between the two subspecies were not confounded by sexual dimorphism in size or shape (Fig. S1).

Bottom Line: AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates.Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST.We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

ABSTRACT
The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel) into two subspecies, Chamaeleo chamaeleon recticrista (CCR) and C. c. musae (CCM). CCR mostly inhabits the Mediterranean climate (northern Israel), while CCM inhabits the sands of the north-western Negev Desert (southern Israel). AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097), consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA) fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year old marine barrier at the Jezreel Valley exactly where the mtDNA clusters meet. We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits.

Show MeSH
Related in: MedlinePlus