Molecular systematics and patterns of morphological evolution in the Centropagidae (Copepoda: Calanoida) of Argentina

Abstract

Recent studies have shown the value of complementing standard taxonomy with genetic analyses to reveal cryptic diversity and to aid in the understanding of patterns of evolution. We surveyed variation in the COI mitochondrial gene in members of the three genera of centropagid copepods from the inland waters in Argentina. In general, we found a close association between molecular and morphological systematics in this group. Similar to findings for marine calanoids, genetic distances within Boeckella species were modest ( < 4%), while distances among morphospecies were much larger ( > 11%). Parabroteas is currently monotypic, although we detected cryptic genetic diversity, with two lineages showing 5.5% divergence. In contrast, Karukinka was not a valid genus, apparently representing an interesting and atavistic offshoot of B. poppei , a result reinforcing the value of considering both morphological and molecular evidence. Moreover, we used combined genetic and morphological information, analysed with maximum likelihood methods, to evaluate the common assumption that evolution tends to proceed via the loss of structures in crustaceans. Although analysis of other taxa and character types is required to evaluate fully the reduction hypothesis, our results suggest that structures may be gained readily as well as lost.

Genetic variability and divergence of Neutrodiaptomus tumidus Kiefer 1937 (Copepoda: Calonida) among 10 subpopulations in the high mountain range of Taiwan and their phylogeographical relationships indicated by mtDNA COI gene

“…Geographical isolation, limited dispersal ability, and low gene flow between subpopulations have been the major cause of the independent evolution among subpopulations. The most geographical distant group between DG-SS and SL with genetic distance greater than 14% is subjected to difference at species level as suggested by many authors for different crustacean groups (Adamowicz and Purvis 2005;Adamowicz et al 2007;Costa et al 2007;Markow and Pfeiler 2010).…”

An all-conquering ecological journey: from the sea, calanoid copepods mastered brackish, fresh, and athalassic saline waters

“…secondary increases in segmentation and setation) are rare. Using both morphological and molecular data, Adamowicz et al (2007a) tested this assumption on a taxon set consisting of 14 South American centropagid copepod species belonging to the genera Boeckella and Parabroteas Mrázek, 1901 (as well as to the now synonymized genus Karukinka Menu-Marque, 2002). They concluded, from their analysis of character evolution, that a hypothesis of strict oligomerization (that serial structures evolve solely by loss or fusion) was not supported, and that for Boeckella, their results suggested that structures were gained repeatedly.…”

Morphometric differences in two calanoid sibling species, Boeckella gracilipes and B. titicacae (Crustacea, Copepoda)

“…It is possible to find marked differences in the morphology of the fifth thoracopod in populations of the same species, as observed for B. poppei (aDaMowiCZ et al, 2007). The aim of the present study is to perform a morphometric comparison of males of B. gracilipes collected in a Patagonian Lake (Riñihe Lake) with males of B. titicacae from Titicaca Lake and with males of a third population of B. gracilipes collected in shallow ponds of Salar de Surire.…”