Mitochondrial DNA reveals monophyly of New Zealand’s Gobiomorphus (Teleostei: Gobiidae: Eleotridae) amongst a morphological complex
2009
Stevens, M. | Hicks, B.
Goal: To examine the phylogenetic relationships within Gobiomorphus to explore Australasian biogeography, origins (single or multiple), and evolutionary loss of a marine life stage (loss of diadromy). Methods: We analyse a fragment of the mitochondrial DNA (Cyt-b) using phylogenetic analyses, and use several meristics (spines, rays, and vertebrae) in a discriminant function analysis. Organisms: All nine species of the genus Gobiomorphus (Eleotridae) found in New Zealand and Australia, with the two Australian Philypnodon species included as outgroup taxa. Conclusions: Monophyly of the genus and all seven New Zealand species was strongly supported. The New Zealand Gobiomorphus are likely to be the result of a single introduction and to have been isolated from Australia since the Miocene or Pliocene (-18-28 Myr ago). These dates correspond well to the oldest fossil in New Zealand dated at 16-20 Myr. Diadromy was consistently at the root of the New Zealand group, and non-diadromy and morphological diversification among these species appears to have occurred relatively recently, with meristic comparisons supporting the molecular analyses. However, among the non-diadromous forms, species morphology contrasts with the molecular data suggesting a recent evolutionary history driven by ecological selection.
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