Marcus K. Drotz

Multiple origins of elytral reticulation modifications in the west palearctic Agabus bipustulatus complex (Coleoptera, Dytiscidae)

The Agabus bipustulatus complex includes one of Europes most widely distributed and common diving beetles. This complex, which is known for its large morphological variation, has a complex demographic and altitudinal variation in elytral reticulation. The various depth of the reticulation imprint, both in smaller and larger meshes, results in both mat and shiny individuals, as well as intermediate forms. The West Palearctic lowland is inhabited by a sexually dimorphic form, with shiny males and mat females. In mountain regions, shiny individuals of both sexes are found intermixed with mat individuals or in pure populations in central and southern areas, whereas pure populations of mat individuals are exclusively found in the northern region at high altitude. Sexual selection is proposed as a driving force in shaping this variation. However, the occurrence of different types of reticulation in both sexes and disjunct geographical distribution patterns suggest an additional function of the reticulation. Here we investigate the phylogeographical history, genetic structure and reticulation variation of several named forms within the Agabus bipustulatus complex including A. nevadensis. The molecular analyses recognised several well-supported clades within the complex. Several of the named forms had two or more independent origins. Few south European populations were uniform in reticulation patterns, and the males were found to display large variation. Reticulation diversity and population genetic variability were clearly correlated to altitude, but no genetic differences were detected among populations with mixed or homogenous forms. Observed reduction in secondary reticulation in female and increased variance in male at high altitude in South Europe may be explained by the occurrence of an additional selective force, beside sexual selection. The combined effect of these selective processes is here demonstrated in an extreme case to generate isolation barriers between populations at high altitudes. Here we discuss this selective force in relation to thermal selection.

Molecular connectedness between self and none self-sustainable populations of Chinese mitten crab (Eriocheir sinensis, H. Milne Edwards, 1853) with focus to the Swedish Lake Vänern and the Oder and Vistula River in Poland.

The highly invasive Chinese mitten crabs (Eriocheir sinensis) was studied to reveal the genetic relationship between three none self-sustainable population within the Polish Oder and Vistula River and Lake Vänern in Sweden. Crabs from self-sustainable populations were collected from the Elbe River (Germany), San Francisco Bay (USA) and five Asian river estuaries. Both parsimony and maximum likelihood analysis of the nuclear ITS 1 and ITS 2 regions reveal a similar topological pattern. The mitochondrial cytochrome c oxidase subunit I (COI) sequence had too low resolution to be informative. The Oder River haplotypes showed high sequence similarities to both the Elbe population and/or the native spawning areas in China. The Vistula River showed haplotypic similarity to specimens from the Oder River in Poland or the Elbe River. Also high sequence similarities were observed to the specimens from the Swedish Lake Vänern indicating to an origin from the River Elbe. Minor changes in evolutionary interpretation exist depending on how gaps are treated and the analytic method. There is a complex movement involving back and forth transoceanic colonization of the Chinese mitten crab haplotypes. Invasion routes are discussed in relation to ship transfer routes and canal waterways.

Ecotype Differentiation in the Face of Gene Flow within the Diving Beetle Agabus bipustulatus (Linnaeus, 1767) in Northern Scandinavia

The repeated occurrence of habitat-specific polyphyletic evolved ecotypes throughout the ranges of widely distributed species implies that multiple, independent and parallel selection events have taken place. Ecological transitions across altitudinal gradients over short geographical distances are often associated with variation in habitat-related fitness, these patterns suggest the action of strong selective forces. Genetic markers will therefore contribute differently to differences between ecotypes in local hybrid zones. Here we have studied the adaptive divergence between ecotypes of the water beetle Agabus bipustulatus along several parallel altitudinal gradients in northern Scandinavia. This water beetle is well known for its remarkable morphological variation associated with mountain regions throughout the western Palaearctic. Two morphological ecotypes are recognised: a montane type with reduced flight muscles and a lowland type with fully developed muscles. Using a multilocus survey of allozyme variation and a morphological analysis with landmark-based morphometrics, across thirty-three populations and seven altitudinal gradients, we studied the local adaptive process of gene flow and selection in detail. Populations were sampled at three different elevations: below, at and above the tree line. The results indicate that the levels of divergence observed between ecotypes in morphology and allele frequencies at α-Glycerophosphate dehydrogenase relative to those shown by neutral molecular markers reflects local diversifying selection in situ. Four main lines of evidence are shown here: (1) A repeated morphological pattern of differentiation is observed across all altitudinal transects, with high reclassification probabilities. (2) Allele and genotype frequencies at the α-Gpdh locus are strongly correlated with altitude, in sharp contrast to the presumable neutral markers. (3) Genetic differentiation is two to three times higher among populations across the tree line than among populations at or below. (4) Genetic differentiation between ecotypes within independent mountain areas is reflected by different sets of allozymes.

Morphometric and genetic analysis shows that Haliplus wehnckei is a junior synonym of H. sibiricus (Coleoptera: Haliplidae)

Specimens of the two nominal species Haliplus sibiricus Motschulsky, and H. wehnckei Gerhardt, were examined by enzyme electrophoresis and morphometrical methods. Beetles collected from five different localities along the north Swedish coast were screened at ten different loci, and paramere shape variation was studied using Elliptic Fourier description. Wrights F-statistics were computed to assess population structure, and PLS-analysis (Projections to Latent Structures modelling) to estimate shape differences. We revise the distribution of the two species in Sweden. The results show a gross overlap and sympatry. Paramere shape analyses indicate the existence of two different forms, which change in frequency with latitude. There are morphologically intermediate specimens that would be difficult to place into either species. Genetic data do not support the nominal species status, and FST-values indicate moderate genetical differences between the populations. We propose that H. sibiricus and H. wehnckei are conspecific. They are either subspecies, or represents two different morphotypes of a clinally varying character. Our data support the latter. Accordingly, H. wehnckei Gerhardt, 1877, is a junior synonym of H. sibiricus Motschulsky, 1860, syn. n.

Changing Names with Changed Address: Integrated Taxonomy and Species Delimitation in the Holarctic Colymbetes paykulli Group (Coleoptera: Dytiscidae)

Species delimitation of geographically isolated forms is a long-standing problem in less studied insect groups. Often taxonomic decisions are based directly on morphologic variation, and lack a discussion regarding sample size and the efficiency of migration barriers or dispersal/migration capacity of the studied species. These problems are here exemplified in a water beetle complex from the Bering Sea region that separates North America from Eurasia. Only a few sampled specimens occur from this particular area and they are mostly found in museum and private collections. Here we utilize the theory of integrated taxonomy to discuss the speciation of the Holarctic Colymbetes paykulli water beetle complex, which historically has included up to five species of which today only two are recognized. Three delimitation methods are used; landmark based morphometry of body shape, variation in reticulation patterns of the pronotum exo-skeleton and sequence variation of the partial mitochondrial gene Cyt b. Our conclusion is that the Palearctic and Nearctic populations of C. paykulli are given the status of separate species, based on the fact that all methods showed significant separation between populations. As a consequence the name of the Palearctic species is C. paykulli Erichson and the Nearctic species should be known as C. longulus LeConte. There is no clear support for delineation between Palearctic and Nearctic populations of C. dahuricus based on mtDNA. However, significant difference in size and reticulation patterns from the two regions is shown. The combined conclusion is that the C. dahuricus complex needs a more thorough investigation to fully disentangle its taxonomic status. Therefore it is here still regarded as a Holarctic species. This study highlights the importance to study several diagnosable characters that has the potential to discriminate evolutionary lineage during speciation.

Larval behavioral syndrome does not affect emergence behavior in a damselfly (Lestes congener)

Activity is a key behavioral trait that often mediates a trade-off between finding food for growth and evading predation. We investigated how activity of the damselfly Lestes congener is affected by larval state and predator presence and if larval behavioral type (BT) can be used to predict larval emergence behavior. Activity level of individual larvae was studied without predators at two different physiological states (hungry, fed) and in two predator treatments (familiar or unfamiliar predator cues). Larvae did not adjust their activity depending on state or when subjected to unfamiliar predator cues but a general reduction in activity was seen in the familiar predator treatment. Hence, active individuals remained active compared to their conspecifics, independent of state or predator treatment illustrating the presence of a behavioral syndrome. However, we found no correlation between larval BT and emergence behavior. Active individuals did not differ from less active individuals in any emergence characteristics. The results illustrate that the larval BT occurs in many situations keeping active larvae active even in maladaptive situations. Furthermore, we show that damselfly emergence behavior can be completely decoupled from larval BT, indicating a loss of stability in individual BT during critical stages in ontogeny.