DETECTION OF SPECIES-SPECIFIC CALLS IN NOISE BY ZEBRA FINCHES POEPHILA GUTTATA AND BUDGERIGARS MELOPSITTACUS UNDULATUS: TIME OF FREQUENCY DOMAIN?

ABSTRACT

Two zebra finches and two budgerigars were trained, by operant conditioning, to detect autogenous (self-generated) distance calls in the presence of masking noise. For both species, there were no differences in detection thresholds for normal calls compared to time- reversed calls. Thresholds for autogenous calls were also compared with thresholds of the other species of birds listening to the same call. When detecting a zebra finch call, budgerigars had slightly lower thresholds than that of the zebra finch. On the other hand, when detecting a budgerigar call, zebra finches showed significantly higher thresholds than the budgerigar. From these results, and from what is known about basic hearing capabilities in these species, we conclude that these birds are not using a mechanism which utilizes “matched” or cross-correlational filtering. It is more likely that they are using “frequency-based” filtering in detecting calls in noise.     

SONG REPERTOIRES AND REPERTOIRE SHARING IN A LOCAL GROUP OF BLACKBIRDS

ABSTRACT

The song repertoires of a local group of blackbird Turdus merula males were determined and quantified with respect to individuality and sharing between neighbours. We focused on the long-ranging, introductory whistle part of the song and its motifs of fixed sequences of sounds. These motifs, whether they are used to start the song or placed centrally in the song, constitute the largest units of song that are repeated in the same way every time they are sung. Blackbird motifs therefore are equivalents of song types in other species. The result shows that one needs to analyse more than 200 songs to estimate a male's repertoire, which averaged 44 different motifs. Relative to other species, this is a medium to large song repertoire. The size of the repertoire of start motifs (on average 32) varied only a little between the individuals, whereas that of central motifs (on average 12) varied rather much between the same individuals, suggesting that they form a potential cue for assessment of male quality. The males within the neighbourhood showed a high degree of start motif sharing, which, together with the relatively large repertoires, could be constraining neighbour recognition. However, in most males the possession of a few individually distinctive and frequently repeated motifs could counter such an effect.     

Molecular systematics of flyingfishes (Teleostei: Exocoetidae): evolution in the epipelagic zone

The flyingfish family Exocoetidae is a diverse group of marine fishes that are widespread and abundant in tropical and subtropical seas. Flyingfishes are epipelagic specialists that are easily distinguished by their enlarged fins, which are used for gliding leaps over the surface of the water. Although phylogenetic hypotheses have been proposed for flyingfish genera based on morphology, no comprehensive molecular studies have been performed. In the present study, we describe a species‐level molecular phylogeny for the family Exocoetidae, based on data from the mitochondrial cytochrome b gene (1137 bp) and the nuclear RAG2 gene (882 bp). We find strong support for previous morphology‐based phylogenetic hypotheses, as well as the monophyly of most currently accepted flyingfish genera. However, the most diverse genus Cheilopogon is not monophyletic. Using our novel flyingfish topology, we examine previously proposed hypotheses for the origin and evolution of gliding. The results support the progressive transition from two‐wing to four‐wing gliding. We also use phylogenetic approaches to test the macroecological effects of two life history characters (e.g. egg buoyancy and habitat) on species range size in flyingfishes. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 161–174.     

Systematics of the scimitar babblers (Pomatorhinus: Timaliidae): phylogeny,biogeography, and species‐limits of four species complexes

Monophyly of the scimitar babblers (Pomatorhinus, Xiphirhynchus: Timaliidae), traditionally defined by the characteristic of having long, curved bills, has been questioned by recent molecular phylogenetic results. We examined representatives of all scimitar babbler species complexes, including all distinct lineages of four complexes as well as several potential relatives, and corroborate that Xiphirhynchus and some species of Stachyris group within Pomatorhinus. Pomatorhinus species comprise three separate clades: larger scimitar babblers (Pomatorhinus hypoleucos, Pomatorhinus erythrogenys complexes); orange‐ and coral‐billed scimitar babblers (Pomatorhinus ochraceiceps, Pomatorhinus ferruginosus complexes); and small scimitar babblers (Pomatorhinus schisticeps, Pomatorhinus ruficollis, Pomatorhinus horsfieldii, Pomatorhinus montanus complexes). Additionally, at least two of the traditional species complexes are not monophyletic. Lineages of the ruficollis and schisticeps groups are intertwined, and P. montanus and P. horsfieldi group within the schisticeps complex. Upon revision of four traditional species complexes, P. hypoluecos, P. ferruginosus, P. schisticeps, and P. ruficollis (with 41 subspecies described in total), 27 distinct, independent lineages or phylogenetic species were distinguished. Two contrasting biogeographical patterns are evident in these groups: Sino‐Himalayan areas are either sister to south‐east Asian areas or are embedded within a clade of other Asian areas. The present study demonstrates the need for unraveling the confusion in traditional taxonomy to allow the study of complex biodiversity patterns in tropical Asia. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 846–869.     

On the evolutionary and ontogenetic origins of tool‐oriented behaviour in New Caledonian crows (Corvus moneduloides)

New Caledonian crows (Corvus moneduloides) are prolific tool users in captivity and in the wild, and have an inherited predisposition to express tool‐oriented behaviours. To further understand the evolution and development of tool use, we compared the development of object manipulation in New Caledonian crows and common ravens (Corvus corax), which do not routinely use tools. We found striking qualitative similarities in the ontogeny of tool‐oriented behaviour in New Caledonian crows and food‐caching behaviour in ravens. Given that the common ancestor of New Caledonian crows and ravens was almost certainly a caching species, we therefore propose that the basic action patterns for tool use in New Caledonian crows may have their evolutionary origins in caching behaviour. Noncombinatorial object manipulations had similar frequencies in the two species. However, frequencies of object combinations that are precursors to functional behaviour increased in New Caledonian crows and decreased in ravens throughout the study period, ending 6 weeks post‐fledging. These quantitative observations are consistent with the hypothesis that New Caledonian crows develop tool‐oriented behaviour because of an increased motivation to perform object combinations that facilitate the necessary learning. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 870–877.     

A comparison of behavioural change in Drosophila during exposure to thermal stress

In order to understand how adaptive tolerance to stress has evolved, we compared related species and populations of Drosophila for a variety of fitness relevant traits while flies directly experienced the stress. Two main questions were addressed. First, how much variation exists in the frequency of both courtship and mating among D. melanogaster, D. simulans, and D. mojavensis when each are exposed to a range of temperatures? Second, how does variation in these same behaviours compare among four geographically isolated populations of D. mojavensis, a desert species with a well defined ecology? Our hierarchical study demonstrated that mating success under stress can vary as much between related species, such as D. melanogaster and D. simulans, as between the ecologically disparate pair, D. melanogaster and D. mojavensis. Strains of this latter desert species likewise varied in tolerance, with differences approaching the levels observed among species. The consequences of stress on male courtship differed markedly from those on female receptivity to courtship, as mating behaviours among species and among strains of D. mojavensis varied in subtle but significant ways. Finally, a comparison of variation in thermotolerance of F₁ hybrids between the two most extreme D. mojavensis populations confirmed that genetic variation underlying traits such as survival or the ability to fly after heat stress is completely different. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83 , 197–205.     

Biogeography in the Death Valley region: evidence from springsnails (Hydrobiidae: Tryonia)

Allozyme and mitochondrial DNA variation were analysed to examine evolution of the nine species of springsnails (genus Tryonia) living in the Death Valley system (Owens and Amargosa basins) of southeastern California and southwestern Nevada. Both allozyme and mtDNA evidence indicate that this highly endemic fauna is non-monophyletic. Species from the upper Amargosa basin comprise a clade most closely related to snails living in the Colorado basin. Snails from the lower Amargosa basin (Death Valley trough) reflect a complex evolutionary history and two of these species are more closely related to an estuarine species from western California than to other snails of the region. These results indicate a commonality of pattern with the well-studied Death Valley pupfishes (Cyprinodon), which also are non-monophyletic and include species that are most closely related to Colorado basin congeners. These biogeographic patterns are interpreted within the context of a recently proposed model for the early history of the lower Colorado River.     

Surface Ultrastructure of Some Tests of Recent Foraminiferida from the Dry Tortugas, Florida

SYNOPSIS. The surface ultrastructure of 10 species of benthic Foraminiferida from the Dry Tortugas, Florida, has been investigated using an electron microscope. Tests of miliolid Foraminiferida appear to be made up of at least 2 distinct layers. An outermost pavement-like layer, consisting of a single layer of calcite rhombohedrons, and an underlying "randomly oriented layer" comprise most of the wall thickness. It was possible to differentiate each miliolid species on the basis of a statistical analysis of calcite rhombs making up the pavement-like layer. Pseudopores were found on the tests of Miliolinella subrotunda (Montagu) and Archaias angulatus (Fichtel and Moll). None of these pseudopores completely penetrated the wall, and all floored in the "randomly oriented layer." It is believed that these structures are formed at time of calcification, rather than secondarily at some later time.
Calcification in Foraminiferida appears to be a biphasic process similar to that found in most other organisms. Groups of crystals were discernible on surfaces of most porcelaneous and "radiate" calcareous species. This suggests that parallel growth of crystals may be an important process in calcification of many Foraminiferida.
A sieve-plate was found in a canal paralleling the test's surface in Cymbaloporetta squammosa (d'Orbigny).     

Associations with habitat versus geographic cohesiveness: size and shape of Bembicium vittatum Philippi (Gastropoda: Littorinidae) in the Houtman Abrolhos Islands

In the Houtman Abrolhos Islands, Western Australia, the direct-developing littorine snail Bembicium vittatum occupies a wide range of habitats, which are replicated across the three major groups of islands. Earlier studies showed that allozyme similarities followed patterns related to gene flow, independent of habitat, providing an excellent opportunity to test for associations with habitat for traits more likely to be adaptively important. As the first test for adaptive divergence, we examined variation in size and shape of shells among 131 populations in the Abrolhos Islands. Two-fold variations were found in width of adults, the allometric coefficient of height with width, and shell height scaled to a standard width. Quantification of habitat characteristics was summarized by principal components analysis. In contrast with the patterns of divergence for allozymes, shell height, adjusted for width, was strongly associated with habitat: flatter shells are found on exposed, vertical shores, while domed, more globose shells predominate in sheltered sites. This association was stronger for shape of adult-sized snails than for height scaled to an arbitrary size, highlighting the importance of using biologically relevant measures. Even highly isolated and allozymically less variable populations in tidal ponds conformed to this association. Because differences in shape are highly heritable in B. vittatum , this association of shape with habitat, independent of patterns of gene flow, indicates local adaptation. Shell size also varied with habitat, but because growth rate is highly plastic, variation in size cannot be interpreted simply in terms of adaptation. Nevertheless, the pattern of variation indicates that, within realized limits, larger size is generally favourable, but may be constrained by local conditions. Thus, variation in size signals the potential for adaptive divergence of life histories among the many, isolated populations of this species.