Morphological diversity of the stone crayfish − traditional and geometric morphometric approach

Abstract

Austropotamobius torrentium is one of four native European crayfish species inhabiting Croatian freshwaters. Existence of eight divergent monophyletic mtDNA phylogroups was described within A. torrentium; six of them are distributed in Croatia, with the highest genetic diversity established in its northern-central Dinaric region. Recent small-scale study of the stone crayfish morphological variability indicated significant differences among different phylogroups. In the present study larger sample size, covering populations from five phylogroups, was analysed with the aim of determining whether there are morphological characteristics that reliably separate stone crayfish from different phylogroups. Aiming this, 245 stone crayfish were analysed through traditional (TM) and, for the first time, geometric morphometric (GM) analyses. Multivariate discriminant analyses included 24 TM characteristics per crayfish, while GM comprised analyses of 22 landmarks on the dorsal side of cephalon. Both methods revealed congruent results, and significant differences among phylogroups in analysed features were obtained, with the cephalon shape contributing the most to crayfish discrimination. Research confirmed that both approaches, combined with statistical methods, are useful in distinguishing and separating crayfish phylogroups. Findings of present study are compatible with the previous molecular findings; stone crayfish present several distinct evolutionary lineages whose species status are currently undefined and require urgent clarification.

Application of the geometric morphometrics approach in the discrimination of morphological traits between brown trout lineages in the Danube Basin of Croatia

“…Digitization error is usually low when performed by the same operator (Fruciano, 2016). Procrustes ANOVA used for error estimation showed that the mean square for individual variation of centroid size and shape was higher than the measurement error, and repeatability values were estimated to be high enough to continue with further analysis (Benítez Fruciano, 2016;Koo and Li, 2016;Lovrenčić et al, 2020). Size-related allometric shape variation was removed from the data because of the different size ranges between group samples and the lack of small individuals in the Atlantic lineage sample (Tab.…”

New insights into the genetic diversity of the stone crayfish: taxonomic and conservation implications

“…The meristics ([ 22 ], this study Additional file 7 ) and geometric morphometrics [ 23 ] could separate crayfish belonging to different phylogroups to some extent, but variation in studied characters, within groups, was evident. Obtained results demonstrated freshwater crayfish plasticity and high intraspecific morphological variation which reflects both the environmental influence and genetic background.…”

“…Recently, Maguire et al [ 22 ] discovered differences among distinct populations (representing different mtDNA phylogroups defined by preciding genetic analyses [ 4 ]) of the stone crayfish in a small geographical region in Croatia. This was achieved by analysing a number of individual morphometric and meristic characteristics with these findings corroborated by a large scale geometric morphometric analyses applied to stone crayfish populations for the first time [ 23 ]. Even though these studies confirmed morphological delineation between phylogroups (the cephalon shape being pertinent), it was shown that morphological variation within phylogroups is also present [ 22 , 23 ].…”

“…This was achieved by analysing a number of individual morphometric and meristic characteristics with these findings corroborated by a large scale geometric morphometric analyses applied to stone crayfish populations for the first time [ 23 ]. Even though these studies confirmed morphological delineation between phylogroups (the cephalon shape being pertinent), it was shown that morphological variation within phylogroups is also present [ 22 , 23 ]. Freshwater crayfish are known to exhibit high intraspecific morphological variation and plasticity reflecting environmental influence and/or genetic background [ 22 , 24 , 25 ].…”

An integrative approach challenges species hypotheses and provides hints for evolutionary history of two Mediterranean freshwater palaemonid shrimps (Decapoda: Caridea)

“…A number of works have examined the usefulness of the two methods in tackling the same questions and found them to be useful in establishing boundaries between species (e.g. Parsons et al 2003;Navarro et al 2004;Fruciano et al 2011;Schmieder et al 2015;Ramírez-Sánchez et al 2016;Lovrenčić et al 2020). Nonetheless, taxonomic studies supported by geometric morphometrics (i.e.…”