Page 1 - Delicado_Machordom_2015

Zoologica Scripta

Effects of habitat transition on the evolutionary
patterns of the microgastropod genus Pseudamnicola

(Mollusca, Hydrobiidae)

DIANA DELICADO,ANNIE MACHORDOM &MARIAN A. RAMOS

Submitted: 8 October 2014 Delicado, D., Machordom, A., Ramos, M.A. (2015). Effects of habitat transition on the evo-
Accepted: 8 January 2015 lutionary patterns of the microgastropod genus Pseudamnicola (Mollusca, Hydrobiidae). —
doi:10.1111/zsc.12104 Zoologica Scripta, 44, 403–417.
Molecular phylogenies of extant species are considered effective tools to infer mechanisms
of speciation. Here, we benefit from this utility to investigate the evolutionary history of an
organismal group linked to different aquatic ecosystems, the microgastropod genus Pseu-
damnicola (family Hydrobiidae). Previous studies have found around 45 species of the nomi-
nal subgenus P. (Pseudamnicola), most of them in coastal stream localities of several
Mediterranean islands and mainland territories, whereas only 12 species of the other subge-
nus, P. (Corrosella), have been collected from springs and headwaters of mountainous
regions of the Iberian Peninsula and south of France. As springs often act as isolated habi-
tats affecting dispersion and constraining gene flow, we supposed that the temporal history
and mode of diversification of species from both subgenera should differ and therefore be
reflected in their phylogenetic patterns. To assess this hypothesis, we performed a molecular
phylogeny based on mitochondrial and nuclear DNA sequences and later conducted an
independent analysis to examine the potential effect of certain geographic and ecological
variables in the genetic divergences of the subgenera. Additionally, we estimated the ances-
tral area of diversification of both groups. Published anatomical revisions and our molecular
analyses suggest that the genus Pseudamnicola should be divided into three genera: the two
previous subgenera plus a new one described here. As postulated, the evolution of the
spring organisms was strongly related to habitat fragmentation and isolation, whereas dis-
persal followed by divergence seem to have been the most common speciation processes for
euryhaline species inhabiting coastal streams and low river stages in which waters remain
connected. On the contrary, rather than habitat fragmentation or dispersion, environmental
conditions have played a larger role during the deep divergent split leading to the three
genera.
Corresponding author: Diana Delicado, Justus Liebig Universit€ at Giessen, Heinrich-Buff-Ring
26-32 IFZ, D-35392 Giessen, Germany/ Museo Nacional de Ciencias Naturales (CSIC), Jos e
Gutierrez Abascal 2, 28006 Madrid, Spain. E-mail: didelicado@gmail.com
Diana Delicado, Department of Animal Ecology and Systematics, Justus Liebig University, Hein-
rich-Buff-Ring 26-32 IFZ, D-35392 Giessen, Germany and Museo Nacional de Ciencias Naturales
(CSIC), Jose Gutierrez Abascal 2, 28006 Madrid, Spain. E-mail: didelicado@gmail.com
Annie Machordom and Marian A. Ramos, Museo Nacional de Ciencias Naturales (CSIC), Jos e
Guti errez Abascal 2, 28006 Madrid, Spain. E-mail: annie@mncn.csic.es, m.ramos@mncn.csic.es

Introduction they represent hypothesis about the speciation events that
The current species diversity is a result of the interaction originated the extant organisms (Barraclough & Nee 2001;
of several evolutionary and ecological processes which gen- Stadler & Bokma 2013). Traditionally, lineages divergence
erate and define each species. In the last decades, evolu- in allopatry is considered the most frequent scenario for
tionary biologists have investigated such driving forces speciation (Endler 1977; Coyne & Orr 2004), modulated
through the reconstruction of species-level phylogenies, as by population dispersion and the presence of geographic

ª 2015 Royal Swedish Academy of Sciences, 44, 4, July 2015, pp 403–417 403