Karyotype analysis and polyploidy in Palaua and a comparison with its sister group Fuertesimalva(Malvaceae)

Palaua(Malveae,Malvaceae)comprises 15 species endemic to the hyperarid coastal desert of Chile and Peru.So far,chromosome counts have been known for two diploid species(2n=2x=10)only.Here we report new chromosome numbers for 12 species of Palaua and four of its sister group Fuertesimalva.Karyotypes including 4,6-diamidino-2-phenylindole dihydrochloride(DAPI)/chromomycin(CMA3)fluorescent banding are presented for selected species representative of each of the main clades of Palaua.An important finding is the discovery of polyploids in one exclusively tetraploid species(P.trisepala)and four species with mixed diploid and tetraploid cytotypes(P.dissecta,P.mollendoensis,P.moschata,and P.tomentosa).The diploid and tetraploid karyotypes are all unimodal,symmetrical and show one or two pairs of satellite chromosomes with their associated CMA+/DAPI- band depending on the cytotype.For some of the tetraploids an autopolyploid origin is suggested.     

Quantification of bird migration by radar – a detection probability problem

Besides the scientific interest in the quantification of bird migration, there is an increasing need to quantify bird movements for the assessment of bird collision risk with artificial structures. In many environmental impact studies, the radar method is used in an inappropriate manner. The processing of echoes consists often of counting blips within defined screen fields, and the surveyed volume is estimated without reference to the detection probabilities of different 'target sizes' (radar cross-sections). The aim of this paper is to present a procedure to quantify bird migration reliably using radar by stating the theoretical requirements of every single step of this procedure and presenting methodological solutions using our own radar data from extensive field studies. Our methodological solutions can be applied to various radar systems, including widely used ship radar. The procedure presented involves discriminating the echoes of birds and insects and estimating the different detection probabilities of differently 'sized' birds (radar cross-sections). By ignoring the different detection probabilities, density estimations may be wrong by as much as 400%. We fear that quantification of bird migration and predicted bird numbers affected by collisions with artificial structures are in many cases based on unreliable estimates.