35 research outputs found
Sind die Sozialwissenschaften Naturwissenschaft?
Die Erörterung der Themenfrage wird mit der Vorausantwort: 'ja selbstverständlich nein' eröffnet. Dieser Widerspruch, der sich in der Antwort zeigt, weist auf das zu klärende Problem hin, ob es ein Widerspruch ist, sich der ganzen Wirklichkeit des Menschen als Gesellschaftswesen nur mit naturwissenschaftlichen oder sozial- und geisteswissenschaftlichen Erkenntnismethoden bemächtigen zu wollen. Verläßt man die Ebene der Klassifizierung von Wissenschaften, geht man also nicht davon aus, daß es sich um inkompatible Sichtweisen der Wirklichkeit handelt, so wird sehr schnell deutlich, daß die Verfahren der Erkenntnisgewinnung und Wissenssicherung Unterschiede aber auch viele Gemeinsamkeiten aufweisen. Letztendlich gibt es einen Schnittpunkt, an der sich alle Wissenschaft vereinigt, nämlich am Menschen, der zu wissen sucht. (NG
Stridulations Reveal Cryptic Speciation in Neotropical Sympatric Ants
The taxonomic challenge posed by cryptic species underlines the importance of using multiple criteria in species delimitation. In the current paper we tested the use of acoustic analysis as a tool to assess the real diversity in a cryptic species complex of Neotropical ants. In order to understand the potential of acoustics and to improve consistency in the conclusions by comparing different approaches, phylogenetic relationships of all the morphs considered were assessed by the analysis of a fragment of the mitochondrial DNA cytochrome b. We observed that each of the cryptic morph studied presents a morphologically distinct stridulatory organ and that all sympatric morphs produce distinctive stridulations. This is the first evidence of such a degree of specialization in the acoustic organ and signals in ants, which suggests that stridulations may be among the cues used by these ants during inter-specific interactions. Mitochondrial DNA variation corroborated the acoustic differences observed, confirming acoustics as a helpful tool to determine cryptic species in this group of ants, and possibly in stridulating ants in general. Congruent morphological, acoustic and genetic results constitute sufficient evidence to propose each morph studied here as a valid new species, suggesting that P. apicalis is a complex of at least 6 to 9 species, even if they present different levels of divergence. Finally, our results highlight that ant stridulations may be much more informative than hitherto thought, as much for ant communication as for integrative taxonomists
Species specificity of electric organ discharges in a sympatric group of gymnotid fish from Manaus (Amazonas)
We collected weakly electric gymnotoid fish in the vicinity of Manaus, Amazonas, in the Solimoes river (white water). We tried to find out whether Electric Organ Discharges (EODs) are species specific which is essential for their presumed role in recognition of conspecifics and reproductive isolation. We considered at least 43 valid sympatric species, some of them unnamed. All of these displayed stable EOD waveform patterns, most of them clearly distinct from the other species' EODs. Eleven species are of the pulse EOD type, 32 of the wave EOD type (one of the latter is
intermediate). The EODs of pulse species were analysed (1) by EOD repetition rate at rest (variation from £1 Hz to 60 Hz), (2) by Fourier amplitude spectrum analysis of single EODs (Fig. 1; in these spectra, frequencies of peak amplitude ranged up to 2300 Hz). There was a significant, positive correlation between both parameters (Fig. 2). Identification of pairs of species with similar EODs by these parameters does not appear to be possible because of inter-individual EOD variations. In wave species there is
conclusive evidence that EOD fundamental frequencies (= repetition rate of a complete EOD period) do not allow species identification: twentyeight wave species displayed EOD fundamental frequencies flrom 300 to 1800 Hz (Fig, 3). This yields a hypothetical frequency band of p.09 octave
to signal species identity; the actual value of EOD frequency variations in Eigenmannia is much greater (1.2 octaves). Seven species of the family Apteronotidae displayed a new signal type: the main energy of the signal
was contained in higher harmonics, and not at the fundamental frequencies (Figs. 6 and 7). For all wave species there was a significant, positive correlation between their dominant frequency (= the strongest signal component) and harmonic content of their EOD although individual species deviated considerably from what was predicted by the regression line (Fig. 8 ) . Thus separation of species was greatly improved compared to the
criterion of fundamental frequency (Fig. 3) but still appeared insufficient in a number of cases.
Therefore, in both wave and pulse species still other parameters must be involved in recognition of conspecifics
Jewish intellectual life and German scientific culture during the Weimar period: the case of the Kaiser Wilhelm Society
Weimar Germany was a great period in scientific development in which Jews played a prominent role. However, Nazi anti-Jewish policies led to the dismissal of many staff members and directors of the institutes of the Kaiser Wilhelm Society, who were forced to go abroad. In their new environment they became major leaders in science notably in the new branches such as molecular biology with a continuing loss to Germany.