The evolution of release and advertisement calls in green toads (Bufo viridis complex)

In the present paper we tested the hypothesis that differences in the acoustic communication system of diploid and tetraploid green toads ( Bufo viridis complex) might be due to selection for reproductive character displacement. We recorded two acoustic signals of the toad repertoire − the advertisement call (a long range mate-attracting signal) and the release call (a short-range signal mediating male–male interactions) − from six sympatric Central Asian populations (three diploid and three tetraploid populations) as well as from three allopatric diploid populations from Italy, and compared their patterns of variation with the pattern of among-population genetic distances. Although release and advertisement calls share the same morpho-physiological constraints, they show significantly different patterns of variation. Release calls vary congruently with the pattern of genetic distances, suggesting that mutation and genetic drift have been the major forces responsible for their change both in time and space. By contrast, the pattern of advertisement-call variation is not consistent with the phylogeny of the group, because the advertisement calls of Asian diploid and tetraploid populations differ from each other more than their genetic distances would predict. These results strongly support the hypothesis that selection acted on the advertisement calls of either or both Asian taxa , possibly, to favour reproductive isolation.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77, 379–391.     

CONSUMERS REPORT PREFERENCES WHEN THEY SHOULD NOT: A CROSS-CULTURAL STUDY

If a chi‐squared analysis were to be performed to determine whether preferences were significant in a paired preference test, the appropriate expected frequencies in the analysis would represent those that would occur should the consumers have no preference. One way of determining these ‘no preference’frequencies, for a particular test situation, would be to note the preference responses obtained when the stimuli were putatively identical. Over 2000 consumers were given paired preference tests in which the stimuli were putatively identical. Response conditions and consumer groups were varied and the proportions of preference and no preference responses were noted. In a preliminary experiment, further research was seen to be justified when for putatively identical stimuli, judges did not exclusively express lack of preference; many expressed a preference for one or other of the stimuli. Further experiments were conducted using a written response condition and putatively identical potato chips (potato crisps) as stimuli. Using a single ‘no preference’option, variation in the placement of this option at either first, second or third place on the response sheet had no significant effect on the response frequencies. The proportion of ‘no preference’responses was approximately 30% in all cases. A previously reported 40‐20‐40 distribution was not always confirmed. The experiment was repeated with Korean consumers; these had fewer ‘no preference’responses. Deriving preferences from hedonic scales, rather than having judges respond to preference options, increased the proportion of ‘no preference’responses, with American judges still having more than Korean judges. Yet there are logical objections to extracting preference data from hedonic scales. Increasing the number of ‘no preference’options to two or three, had the effect of increasing the number of ‘no preference’responses up to as much as approximately 60%. Extending the results to Koreans, using two ‘no preference’options, it was seen that only the judges in an anonymous response condition had significantly fewer ‘no preference’responses than Americans. The use of these response frequencies as expected frequencies in chi squared analyses was illustrated, after adjustments for counterbalancing.     

The allopolyploid origin of Narcissus obsoletus (Alliaceae): identification of parental genomes by karyotype characterization and genomic in situ hybridization

Karyological and genomic in situ hybridization (GISH) approaches provided evidence of the parentage and origin of the hybrid species Narcissus obsoletus. Here, we demonstrate that the putative parental species, N. serotinus L. and N. elegans (Haw.) Spach, recently proposed because of their intermediate morphological traits, have participated in the hybridization process forming this taxon. Karyotype characterization of parental genomes in populations from S Spain and N Morocco has revealed differences in chromosome length and karyotype asymmetry, highlighting their diploid nature. Multicolour GISH on metaphase plates of N. obsoletus, with N. serotinus and N. elegans DNA used as probes, showed differential fluorescent staining of 10 and 20 chromosomes from parental genomes, respectively. Both parental genomes were detected in the allopolyploid, albeit in a duplicated manner. Secondary hybridization between N. obsoletus and N. serotinus was also detected karyologically. Little karyological differentiation between different geographic regions was found in either N. serotinus or N. obsoletus. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 477–498.     

Disjunctive distribution of the basal genus Aplomerus (Hymenoptera: Ichneumonidae: Xoridinae) in East Asia and North America,with a new species from Japan

The first Japanese representative of the predominantly Nearctic genus Aplomerus Provancher, A. japonicus sp. nov., is described. This species can easily be distinguished from the other species by the black body. Morphologically this species resembles A. lineatulus (Say) from eastern North America but is separable by the sculpture of the propodeum and third metasomal tergite. The discovery of this species demonstrates a disjunctive distribution of the genus Aplomerus in East Asia and North America. Notes on habitat and adult behavior are also given.     

Increased sperm allocation delays body growth in a protandrous simultaneous hermaphrodite

Sex allocation theory for simultaneous hermaphrodites predicts that hermaphrodites have a fixed amount of reproductive resources to allocate to both sex functions and that they trade off their allocation to both sexes depending on environmental conditions. Ophryotrocha diadema is a simultaneous hermaphroditic polychaete worm which has a protandrous phase prior to the hermaphroditic phase. The ability of adolescent males to compete with mature hermaphrodites for egg fertilization and the costs of an increase in male expenditure during the protandrous phase were tested in experiments where adolescent males had the possibility to fertilize hermaphrodites' eggs. Results document that adolescent males were able to compete with hermaphrodites for egg fertilization and caused the hermaphrodites fitness losses of 31.4%. Adolescent males which fertilized hermaphrodites' eggs had a slower growth rate than males which had no possibility to fertilize eggs. This result indicates that an increased male expenditure is a cost for adolescent males and that, during the protandrous phase, resources are allocated to reproduction at the expense of somatic development.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 149–154.