Regional scale speciation reveals multiple invasions of freshwater in Palaemoninae (Decapoda)

Abstract

Regional scale speciation reveals multiple invasions of freshwater in Palaemoninae (Decapoda).-Zoologica Scripta, 41, 293-306. The generic level, systematic relationship in Palaemoninae was inferred from analyses based on the mitochondrial 16S rDNA and nuclear Histone (H3) genes, primarily focussed on the genera Palaemon and Palaemonetes, as previous morphological and molecular studies indicated potential paraphyly in some genera. Palaemonetes, Exopalaemon, Coutierella and certain Palaemon recover as a strongly supported monophyletic clade, but with the exception of Palaemon concinnus, P. pandaliformis and P. gracilis. Within this clade, six major clades are identified with geographic relationships appearing stronger than generic relationships. The data strongly suggest that Palaemon, Palaemonetes, Exopalaemon and Coutierella are synonymous and that the morphological characters currently used to define these genera require re-evaluation. Freshwater species are not closely related to each other, but instead group with geographically close marine species, suggesting multiple invasions of freshwater by physiologically plastic ancestors rather than a single colonisation event with subsequent speciation.

Molecular phylogeny of the genera Palaemon and Palaemonetes (Decapoda, Caridea, Palaemonidae) from a European perspective

“…The separate position of two other species of the subgenus Palaeander, P. northropi (Rankin, 1898), and P. floridanus Chace, 1942, do not support the monophyly of this subgenus. In contrast, in the analyses by Ashelby et al (2012), these species cluster together with different representatives in two separate analyses (16S rDNA and histone H3). However, a fourth species of the subgenus Palaeander, P. semmelinkii (De Man, 1881) seems to be unrelated to P. elegans, P. northropi and P. floridanus (see Ashelby et al, 2012).…”

“…In contrast, in the analyses by Ashelby et al (2012), these species cluster together with different representatives in two separate analyses (16S rDNA and histone H3). However, a fourth species of the subgenus Palaeander, P. semmelinkii (De Man, 1881) seems to be unrelated to P. elegans, P. northropi and P. floridanus (see Ashelby et al, 2012). The validity of this taxon, which was based on the number of mandibular palp segments (2 instead of 3) is thereby definitely refuted.…”

“…The really groundbreaking addition of the present study, and a parallel one by Ashelby et al (2012), is that this paraphyly of Palaemon and Palaemonetes is now expanded to a world-wide scale and includes the type species of the two genera. The different monophyletic clades obtained in our analyses (Fig.…”

Oxygen consumption remains stable while ammonia excretion is reduced upon short time exposure to high salinity in Macrobrachium acanthurus (Caridae: Palaemonidae), a recent freshwater colonizer

“…They occur in a great variety of aquatic environments, from seawater up to full freshwater (Augusto et al 2009, Anger 2013. The family Palaemonidae has a marine origin and passed through various independent events of freshwater invasion (Murphy and Austin 2005, Ashelby et al 2012, McNamara and Faria 2012, Anger 2013. These events have occurred quite recently, ~30 mya (Tertiary), and are still happening (Murphy and Austin 2005, Augusto et al 2007a, b, 2009, Pileggi and Mantelatto 2010, Collins et al 2011, McNamara and Faria 2012.…”

Phylogenetic relationships among the freshwater genera of palaemonid shrimps (Crustacea: Decapoda) from Mexico: evidence of multiple invasions

“…A relevant topic in the evolution of this group is the invasion of freshwater (Ashelby et al, 2012), since typically freshwater epigean palaemonids, such as Macrobrachium, are dependent to a certain degree of marine or brackish waters to complete their larval development. However, a number of species in the subfamily are strictly freshwater inhabitants with populations completely isolated from brackish or marine waters, with reduced dispersal capabilities and often spatially constrained by geographic barriers.…”