Abstract
We compared the morphology of the erythrocytes of five anurans, two toad species - Bufo gargarizans (Cantor, 1842) and Duttaphrynus melanostictus (Schneider, 1799) and three frog species - Fejervarya limnocharis (Gravenhorst, 1829), Microhyla ornata (Dumeril & Bibron, 1841), and Rana zhenhaiensis (Ye, Fei & Matsui, 1995). We then reconstructed the ancestral state of erythrocyte size (ES) and nuclear size (NS) in amphibians based on a molecular tree. Nine morphological traits of erythrocytes were all significantly different among the five species. The results of principal component analysis showed that the first component (49.1% of variance explained) had a high positive loading for erythrocyte length, nuclear length, NS and ratio of erythrocyte length/erythrocyte width; the second axis (28.5% of variance explained) mainly represented erythrocyte width and ES. Phylogenetic generalized least squares analysis showed that the relationship between NS and ES was not affected by phylogenetic relationships although there was a significant linear relationship between these two variables. These results suggested that (1) the nine morphological traits of erythrocytes in the five anuran species were species-specific; (2) in amphibians, larger erythrocytes generally had larger nuclei.
Highlights
Amphibians have evolved an array of adaptive structures and mechanisms to cope with environmental changes that result from their life histories, which involves a transition from water to land (FOXON 1964, WOJTASZEK & ADAMOWICZ 2003)
We found that (1) the mean values of erythrocyte length (EL) and ratio of EL/Erythrocyte width (EW) and nuclear length (NL)/nuclear width (NW) were largest in D. melanostictus and smallest in F. limnocharis, the mean value of EW was larger in B. gargarizans than in the other species, the mean value of erythrocyte size (ES) was larger in B. gargarizans and D. melanostictus than in the other species; (2) the mean values of NL and nuclear size (NS) were largest in D. melanostictus and smallest in F. limnocharis and M. ornata, the mean value of NW was largest in B. gargarizans and smallest in M. ornata; (3) the mean value of nucleo-cytoplasmic ratio was largest in D. melanostictus and R. zhenhaiensis and smallest in M. ornata (Table 1)
The terrestrial habitat has selected a series of adaptive structures and mechanisms in frogs that have enabled them to function under conditions of changeable humidity and partial oxygen pressure in terrestrial environments (BARAQUET et al 2013, FOXON 1964, WOJTASZEK & ADAMOWICZ 2003)
Summary
Amphibians have evolved an array of adaptive structures and mechanisms to cope with environmental changes that result from their life histories, which involves a transition from water to land (FOXON 1964, WOJTASZEK & ADAMOWICZ 2003). We compare the morphology of the erythrocytes of five sympatric anuran species, including two toads – Bufo gargarizans (Cantor, 1842), Duttaphrynus melanostictus (Schneider, 1799) – and three frogs – Fejervarya limnocharis (Gravenhorst, 1829), Microhyla ornata (Duméril & Bibron, 1841), and Rana zhenhaiensis (Ye, Fei & Matsui, 1995) –, sampled from natural populations in Lishui, Zhejiang Province, China These results were combined with recently published accounts on erythrocyte traits (erythrocyte size and nucleus sizes) from three Orders (Gymnophiona, Caudata and Anura) of Amphibia to allow reconstruction of ancestral states and to examine their phylogenetic relationships
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