Multivariate morphometrics of geographic variation of Gerris costae (Heteroptera: Gerridae) in Europe

Abstract

The waterstrider species Gerris costae (Herrich-Schaeffer) has a large and disjunct distribution in the southern part of the palearctic region. Multivariate morphometric techniques were used to assess the geographic variation in the European part of its range, where three subspecies are currently recognized: G. c. costae (Herrich-Schaeffer), G. c. fieberi Stichel, and G. c. poissoni Wagner and Zimmermann. Twelve variables were selected from a larger set (56 or 57 variables for males and females, respectively) by stepwise discriminant analysis, and were found to represent the main patterns of morphometric variation in the full character set. Principal component analysis revealed that both 'size' and 'shape' contribute to geographic differentiation. Canonical variate analysis with two different criteria for the definition of a priori groups showed that the subspecies are coherent units separate from each other, and that the segregation into the three subspecies indeed reflects the main pattern of geographic variation in Europe. Comparisons of field samples with offspring reared in the laboratory under standardized conditions demonstrated that geographic differentiation is genetically determined for the most part. The study therefore supports the segregation of Gerris costae into three subsepcies in the area considered. Linear discriminant functions are given to allocate additional material to the subspecies.

Annotated catalogue of Enicocephalomorpha, Dipsocoromorpha, Nepomorpha, Gerromorpha, and Leptopodomorpha (Hemiptera: Heteroptera) of Turkey, with new records

“…Gheit (1995) reported G. costae from Morocco without indication of the subspecies. Klingenberg (1992) confirmed the validity of the subspecies by multivariate morphometric study. However, Damgaard (2006), based on molecular data, downgraded Gerris sahlbergi Distant, 1879 (Central Asia, Siberia, Mongolia, China, northern India) to a subspecies of G. costae, and further questioned the validity of the included subspecies based on the lack of geographical substructure in the mitochondrial DNA examined.…”

Clinal variation in morphology among eastern populations of the waterstrider, Aquarius remigis Say (Hemiptera: Gerridae)

“…Vicariant speciation has been suggested to be the predominant mode of speciation (Mayr, 1963;Futuyma & Mayer, 1980;Lynch, 1989;Brooks & McLennan, 199 1) and Pleistocene glaciation has been invoked to explain patterns of differentiation within many taxa (Roff et al, 1981;Gollmann, 1984;Seeb et al, 1987;Hamrick & Hamrick, 1989;Hinch, Collins & Harvey, 1991;Klingenberg, 1992). The pattern of morphological variation found in this study supports the hypothesis that the origin of the zone of transition and of the present genetic divergence of the northern and southern 'types' of A. remigis is due to a vicariance event (Gallant et al, 1993).…”

“…Specific characteristics of the genitalia have been used to characterize species of gerrids (Michel, 1961;Polhemus & Chapman, 1979;Andersen, 1990) although they are not thoroughly examined here. Thoracic length, abdominal width and mid-femoral length were among measurements found to be representative of morphological differentiation between subspecies of Gem's costae (Klingenberg, 1992).…”

Introgressive hybridization between two species of waterstriders (Hemiptera: Gerridae: Limnoporus): geographical structure and temporal change of a hybrid zone

“…A set of nine morphometric measurements was selected from a larger set of variables in a preliminary stepwise discriminant analysis ( Klingenberg, 1992) between laboratory‐reared bugs of both species, and augmented with diagnostic characters described by Andersen & Spence (1992, table 3). The final list of variables is the following (numbers correspond to those in figs 2 and 3 of Klingenberg, 1992): length of the mid‐femur (49), length of the mid‐tibia (50), length of the fourth antennal segment (46), width of the head across the eyes (19), length of the thorax measured along the ventral midline (combined 31–33), width of the thorax (17, but measured in ventral view), length of the second to seventh abdominal segments measured along the ventral midline (combined 37–42), length of the seventh abdominal segment measured along the ventral midline (42) and width of the seventh abdominal segment at its anterior margin (27, but measured in ventral view). All morphometric data were taken using a dissecting microscope fitted with a video camera and digital measurement system.…”