Molecular evidence for long-distance colonization in an Indo-Pacific seahorse lineage

Abstract

Mitochondrial control region (mtDNA CR) diversity within and among 6 seahorse populations associated with the Indo-Pacific Hippocampus kuda complex (H. kuda from India, Malaysia, Indonesia and the Philippines, H. fuscus from the Red Sea and H. capensis from South Africa) was compared to determine whether there was support for the hypothesis that seahorses are able to colonize remote areas by means of rafting. Analyses performed on the data-set included phylogenetic reconstructions, estimation of relative population ages, tests for evidence of population expansion, pairwise migration rates and divergence times, as well as relationships between genetic and geographic distances. The mtDNA data indicate that all populations have undergone recent expansions, but that the timing of these events differed. The H. kuda population from India was found to be the oldest, whereas the expansion of the H. fuscus population from the Red Sea took place most recently. The fact that all seahorse populations studied are characterized by a single ancestral mtDNA haplotype and migration rates are low in most cases, as well as the fact that no significant relationship between genetic and geographic distances was found, indicates that colonization of distant habitats by a small number of founding individuals may be common in seahorses associated with the H. kuda complex. As the level of subsequent gene flow among populations is low, this may result in rapid speciation.

Genetic diversity and population structure of the pot-belly seahorseHippocampus abdominalisin New Zealand

“…When investigating the genetic diversity of seahorse species in the Vietnam region using 354 bp of cytochrome b, Lourie et al (1999) found very similar ranges of B1% within and 7.2Á19.4% between species. Furthermore, the nucleotide and haplotype diversities seen here fall within the ranges described for other seahorse species, such as the H. kuda complex (Teske et al 2005), H. capensis (Teske et al 2003) and H. trimaculatus . Casey et al (2004) carried out the largest comparison within the Hippocampus genus, and observed putative intra-specific distances of 1.1Á5.9%, and distances of 1.3Á23.2% between species.…”

Phylogeography of the neon damselfish Pomacentrus coelestis indicates a cryptic species and different species origins in the West Pacific Ocean

“…Most of the past research supports the Center of Origin hypothesis (Barber et al 2006, Williams 2007, Timm & Kochzius 2008, Nuryanto & Kochzius 2009). In contrast, relatively few cases substantiate the Center of Overlap (Teske et al 2005, Gaither et al 2011) and Center of Accumulation hypotheses (Wilson et al 2001, Drew & Barber 2009). Barber (2009 suggested that the central West Pacific's diversity is likely the result of multiple evolutionary processes, working either simultaneously or over different time periods, being dominated by different processes.…”

“…The Center of Overlap suggests that populations in the central West Pacific would be polyphyletic, harboring mixed lineages of different biogeographic demes (Palumbi 1996). Several phylogeographic studies of marine taxa have been conducted to test these hypotheses (Teske et al 2005, Barber et al 2006, Williams 2007, Drew & Barber 2009, Malay & Paulay 2010. However, the results were diverse and inconsistent, possibly due to variation in the biological and ecological characteristics of the different target species of each study.…”

Long-distance dispersal, low connectivity and molecular evidence of a new cryptic species in the obligate rafter Caprella andreae Mayer, 1890 (Crustacea: Amphipoda: Caprellidae)

“…However, patterns in connectivity are difficult to predict based on reproductive traits alone and are likely strongly influenced by multiple biotic and abiotic environmental factors, especially oceanographic processes such as local water circulation patterns (Bowen et al 2006;Nunes et al 2011). In such situations, genetic analysis of population differentiation can provide a powerful tool for investigating dispersal (Teske et al 2005;Thiel and Haye 2006;Goodbody-Gringley et al 2010).…”