Molecular evidence for repetitive parallel evolution of shell structure in Clausiliidae (Gastropoda, pulmonata).

The division of clausiliid genera, using the type of clausilial apparatus (CA) as the decisive criterion, is ambiguous. Two types of CA can be distinguished: the normal (N) type and the Graciliaria (G) type. Morphological resemblance between species with different types of CA led to the hypothesis that the CA type is homoplasious.

Methods in Vicariance Biogeography: Assessment of the Implementations of Assumptions 0, 1, and 2.

As we have argued previously, for the valid derivation of general area cladograms in vicariance biogeography, two requirements should be met. First, sets of area cladograms derived under assumptions 0, 1 and 2 should be inclusive (requirement I). Second, general area cladograms should be based on area cladograms, for different monophyletic groups, derived under the same assumption (requirement II).

Getting better all the time: improving preference scores reflect increases in the strength of filial imprinting.

In the investigation of the neural mechanisms of filial imprinting, neurochemical measures are often correlated with preference score (PS): approach activity to the training stimulus/total approach in a test. In a previous study, domestic chicks, Gallus gallus domesticus, that had a PS under 65% were classed as 'poor learners' and those with a PS greater than 65% were called 'good learners'. We tested the effects of continued imprinting training in chicks from these two categories.

DNA in situ hybridization on polytene chromosomes of Simulium sanctipauli at loci relevant to insecticide resistance.

A DNA technique for in situ hybridization developed by Kumar & Collins (1994) for use on polytene chromosomes of adult Anopheles mosquitoes (Diptera: Culicidae) was modified for use with Simulium larval salivary gland chromosomes (Diptera: Simuliidae). Cloned fragments of several Simulium genes (coding for aspartate amino transferase, cytochrome P450 and DNA polymerase) were successfully mapped physically by assigning specific band locations in Simulim sanctipauli V. & D.

One species or several? Discordant patterns of geographic variation between allozymes and mtDNA sequences among spiders in the genus Metepeira (Araneae: Araneidae).

Paradoxically, an allozyme study of Metepeira "spinipes" (sensu lato) demonstrated extensive gene flow among four populations whose members are nevertheless morphologically and behaviorally distinct. Initially, the authors tentatively concluded that the populations exhibited panmixis and suggested that local environmental effects accounted for the apparent morphological and behavioral differences. However, they later concluded that such differences were too great to be accounted for by the environment alone and that the four populations actually represented three different species.

A single camera roentgen stereophotogrammetry method for static displacement analysis.

A new method to quantify motion or deformation of bony structures has been developed, since quantification is often difficult due to overlaying tissue, and the currently used roentgen stereophotogrammetry method requires significant investment. In our method, a single stationary roentgen source is used, as opposed to the usual two, which, in combination with a fixed radiogram cassette holder, forms a camera with constant interior orientation. By rotating the experimental object, it is possible to achieve a sufficient angle between the various viewing directions, enabling photogrammetric calculations.

Distribution of gastrin-releasing peptide immunoreactivity in the brain of the collared dove (Streptopelia decaocto).

The distribution of immunoreactivity after applying an antibody against gastrin-releasing peptide (GRP) was studied in the brain of the collared dove (Streptopelia decaocto). In the forebrain GRP-immunoreactive (GRP-ir) cells were found in the hyperstriatum accessorium, medial and lateral parts of the neostriatum, corticoidea dorsolateralis and temporoparieto-occipitalis areas, hippocampus, pre- and parahippocampal areas and prepiriform cortex. In the brainstem, GRP-ir cells were restricted mainly to the substantia nigra and ventral tegmental nucleus.

Absence of single-locus complementary sex determination in the braconid wasps Asobara tabida and Alysia manducator.

In species with single-locus complementary sex determination (sl-CSD), sex is determined by multiple alleles at a single locus. In the haplodiploid Hymenoptera, sl-CSD results in females, if individuals are heterozygous at the sex locus, and in males, if individuals are hemizygous (haploid males) or homozygous (diploid males). Several hymenopteran species have been shown to have sl-CSD, but in several others sl-CSD is absent and the phylogenetic distribution remains unclear.

PseudoBase: structural information on RNA pseudoknots.

PseudoBase is a database containing structural, functional and sequence data related to RNA pseudo-knots. It can be reached at http://wwwbio.LeidenUniv.

Song learning with audiovisual compound stimuli in zebra finches.

We investigated the effects of audiovisual compound training on song learning in zebra finches, Taeniopygia guttata. In the first experiment, presentation of a stuffed adult zebra finch male was found to be reinforcing to zebra finch males in an operant task. In a separate experiment, zebra finch males were reared without their father from day 7 after hatching onwards.

PseudoBase: a database with RNA pseudoknots.

PseudoBase is a database containing structural, functional and sequence data related to RNA pseudo-knots. It can be reached at http://wwwbio. Leiden Univ.

Two Requirements for Obtaining Valid Common Patterns under Different Assumptions in Vicariance Biogeography.

In vicariance biogeography, widespread or sympatric taxa can be dealt with under assumptions 0, 1, and 2. Data from cladogenetic relationships among taxa of a monophyletic group and their distribution over areas are assumed, in the order 0 → 1 → 2, to represent decreasing information about vicariance events. A less strict assumption carries a larger solution set, i.

Gregarious development in alysiine parasitoids evolved through a reduction in larval aggression.

Population genetic models have suggested that siblicide between the larvae of parasitoid wasps, once gained, can be lost only under stringent conditions, making transitions from solitary to gregarious development rare. However, phylogenetic studies suggest that gregarious development has evolved on numerous occasions, although the mechanisms are largely unknown. We report experiments, on two morphologically similar species of alysiine braconids, directed at an understanding of how gregarious development evolved in one subfamily.

Phosphorylation state of red and white muscle in tilapia during graded hypoxia: an in vivo (31)P-NMR study.

The aim of this study was to measure the energetic consequences of hypoxia in different types of skeletal muscle within a single tilapia species (n = 5). To that aim, 81.0 MHz (31)P-nuclear magnetic resonance (NMR) spectra were collected, alternately, from three surface coils placed adjacent to the tissues of interest (dorsal white muscle, ventral white muscle, and lateral red muscle) during a graded hypoxia load over 6 h followed by a 5-h recovery period.

Direct and indirect estimates of the selfing rate in small and large individuals of the bumblebee pollinated Cynoglossum officinale L (Boraginaceae).

We measured the relationship between selfing rates and flower number in an experimental population of bumblebee pollinated Cynoglossum officinale, with plants differing in flower number. Results were compared with the prediction of a model based on pollen dynamics and pollinator behaviour. The selfing rate, as measured by multilocus oligonucleotide DNA fingerprinting, increased with flower number and ranged from 0% to 70%.

Late-acting inbreeding depression in both male and female function of echium vulgare (Boraginaceae).

We present data on late-acting inbreeding depression in pollen performance, siring success and seed production in Echium vulgare. Pollen viability and rate of pollen-tube growth were both lower for pollen from plants derived from selfing than for pollen from plants derived from outcrossing. Pollen tube numbers within the styles did not differ for pollen from plants derived from selfing or outcrossing.

The sensory trigeminal system in birds: input, organization and effects of peripheral damage. A review.

The primary sensory trigeminal system in birds comprises the mesencephalic trigeminal nucleus and the trigeminal ganglion with projections to the principal sensory nucleus (PrV) and the descending tract with its subnuclei. Other cranial nerves can contribute to PrV and the descending system that together form the somatosensory system of the head. There is also a proprioceptive component.

Immunohistochemical characterization of forebrain areas in the collared dove (streptopelia decaocto).

The distribution of four neuroactive substances was studied in the telencephalon of the collared dove using enzyme- and immunohistochemistry. The distribution of acetylcholinesterase and dopamine was similar to that described in other birds. Galanin-immunoreactive fibres were found mainly in the paleostriatum primitivum , the medial part of the parolfactory lobe (LPO) and the lateral septal nucleus; galanin may interfere with acetylcholine activity.

What pair formation can do to the battle of the sexes: towards more realistic game dynamics.

In the various dynamic models of Dawkin's Battle of the Sexes, payoff matrices serve as the basic ingredients for the specification of a game-dynamic model. Here I model the sex war mechanistically, by expressing the costs of raising the offspring and performing a prolonged courtship via a time delay for the corresponding individuals, instead of via payoff matrices. During such a time delay an individual is not able to have new matings.

The development of animal behavior: from Lorenz to neural nets.

In the study of behavioral development both causal and functional approaches have been used, and they often overlap. The concept of ontogenetic adaptations suggests that each developmental phase involves unique adaptations to the environment of the developing animal. The functional concept of optimal outbreeding has led to further experimental evidence and theoretical models concerning the role of sexual imprinting in the evolutionary process of sexual selection.

A crossed projection from the optic tectum to craniocervical premotor areas in the brainstem reticular formation. An anterograde and retrograde tracing study in the mallard (Anas platyrhynchos L.).

The optic tectum in birds receives visual information from the contralateral retina. This information is passed through to other brain areas via the deep layers of the optic tectum. In the present study the crossed tectobulbar pathway is described in detail.

Location of reticular premotor areas of a motor center innervating craniocervical muscles in the mallard (Anas platyrhynchos L.).

The supraspinal nucleus (SSp) in the mallard, which lies in the rostral spinal cord and caudal brainstem, is a motor nucleus that forms the rostral continuation of the ventral horn. It contains part of the motoneurons innervating the craniocervical muscles. Injections with horseradish peroxidase (HRP) and wheat germ agglutinin conjugated to HRP (WGA) in the SSp were used to localize the craniocervical premotor neurons in the medullary reticular formation.

Song learning from playback in zebra finches: is there an effect of operant contingency?

Social interaction is often regarded as crucial for song copying in zebra finches, Taeniopygia guttata. Contingencies in the interaction between pupil and tutor might be essential for the song-copying process. The effect of contingency between a pupil's operant behaviour and tutor song has been studied previously, but with contradictory results.

The neural substrate for 'learned' and 'nonlearned' activities in birds: a discussion of the organization of bulbar reticular premotor systems with side-lights on the mammalian situation.

The reticular formation of the brainstem contains premotor systems for various musculomotor systems. In this paper, the bulbar premotor systems for jaw and tongue movements, head and neck movements, locomotion, and respiration and vocalization in birds are reviewed and compared to premotor systems in mammals. Roughly, the bulbar reticular formation can be subdivided in three longitudinal zones: a dorsolateral (RPcdl) and a ventromedial (RPcvm) parvocellular zone and a gigantocellular zone (RGc).