Nutritional implications for nitrogen and mineral budgets from analysis of guano of the big brown bat Eptesicus fuscus (Chiroptera: Vespertilionidae).

1. Analysis of nitrogen, sodium, calcium, magnesium, iron, and potassium levels in big brown bat guano throughout much of the summer roosting period was performed. 2. Based on the tenet that low, non-variable levels of an element in feces indicate dietary inadequacy for that element, female big brown bats are routinely and severely stressed for calcium and may become stressed for iron by the end of the summer. Similar elemental stresses, although not as severe, exist for males.     

An allometric comparison of the mitochondria of mammalian and reptilian tissues: The implications for the evolution of endothermy

Summary The effects of body size and phylogeny on metabolic capacities were examined by comparing the mitochondrial capacities of 6 mammalian and 4 reptilian species representing 100-fold body weight ranges. The mammals examined included 3 eutherian, 2 marsupial and a monotreme species and the reptiles 2 saurian, 1 crocodilian and 1 testudine species. The tissues examined were liver, kidney, brain, heart, lung and skeletal muscle. Allometric equations were derived for tissue weights, mitochondrial volume densities, internal mitochondrial membrane surface area densities, tissue mitochondrial membrane surface areas both per gram and per total tissue and summated tissue mitochondrial membrane surface areas. For the mammals and reptiles studied a 100% increase in body size resulted in average increases of 68% in internal organ size and 107% in skeletal muscle mass. Similarly, total organ mitochondrial membrane surface areas increase in mammals and reptiles by an average 54% and for skeletal muscle by an average 96%. These values are similar to increases in standard (54 and 71%) and maximum (73 and 77%) organismal metabolism values found by other authors for mammals and reptiles respectively. Although the allometric exponents (or rates of change with increasing body size) of the mitochondrial parameters in mammals and reptiles are statistically the same, in general the total amount of mitochondrial membrane surface area in the mammalian tissues are four times greater than found in the reptilian tissues. These differences were not the result of any single ‘quantum’ factor but are the result of the mammals having relatively larger tissues with a greater proportion of their volume occupied by mitochondria and to a lesser extent increases in the internal mitochondrial membrane surface area densities. Mitochondrial volume density from this present study would appear to be the major factor involved in changing weight specific metabolism of tissues both as a result of changes in body size and in the evolution of endothermy in mammals from reptiles.     

Molecular systematics and biogeography of the bent-wing bat complex Miniopterus schreibersii (Kuhl, 1817) (Chiroptera: Vespertilionidae)

The complete mitochondrial ND2 gene (1037 bp) was sequenced to examine relationships within the bent-wing bat complex, Miniopterus schreibersii (Family Vespertilionidae). It was found that M. schreibersii is a paraphyletic assemblage comprising several species. Two major lineages were identified, one of which was restricted to the Palearctic-Ethiopian regions and the other to the Oriental-Australasian regions. This pattern of differentiation was mirrored by the genus as a whole. Speciation and differentiation within the genus Miniopterus appears to have a hierarchical geographical pattern. The earliest divergence corresponds to the Ethiopian-Palearctic and the Oriental-Australasian biogeographical zones. This early divergence is then followed by radiations within each of the Ethiopian, Oriental and Australasian regions. The study also revealed that the number of species currently recognized (11 or 13) is a gross underestimate of the number of actual species. The emerging picture is one of a relatively speciose genus with most species having relatively restricted distributions; few, if any, occur in more than one biogeographical region.     

Base-compositional biases and the bat problem. III. The questions of microchiropteran monophyly.

Using single-copy DNA hybridization, we carried out a whole genome study of 16 bats (from ten families) and five outgroups (two primates and one each dermopteran, scandentian, and marsupial). Three of the bat species represented as many families of Rhinolophoidea, and these always associated with the two representatives of Pteropodidae. All other microchiropterans, however, formed a monophyletic unit displaying interrelationships largely in accord with current opinion. Thus noctilionoids comprised one clade, while vespertilionids, emballonurids, and molossids comprised three others, successively more closely related in that sequence. The unexpected position of rhinolophoids may be due either to the high AT bias they share with pteropodids, or it may be phylogenetically authentic. Reanalysis of the data with varying combinations of the five outgroups does not indicate a rooting problem, and the inclusion of many bat lineages divided at varying levels similarly discounts long branch attraction as an explanation for the pteropodid-rhinolophoid association. If rhinolophoids are indeed specially related to pteropodids, many synapomorphies of Microchiroptera are called into question, not least the unitary evolution of echolocation (although this feature may simply have been lost in pteropodids). Further, a rhinolophoid-pteropodid relationship--if true--has serious implications for the classification of bats. Finally, among the outgroups, an apparent sister-group relation of Dermoptera and Primates suggests that flying lemurs do not represent the ancestors of some or all bats; yet, insofar as gliding of the type implemented in dermopterans is an appropriate model for the evolution of powered mammalian flying, the position of Cynocephalus in our tree indirectly strengthens the argument that true flight could have evolved more than once among bats.     

Immunohistochemical evidence of cone-based ultraviolet vision in divergent bat species and implications for its evolution

We characterized Fos-like expression patterns in the primary visual cortex (V1) by binocular flicking stimulation with UV light to investigate cone-based UV vision in four bat species representing four lineages: Hipposideros armiger and Scotophilus kuhlii, insectivores using constant frequency (CF) or frequency modulation (FM) echolocation, respectively, and Rousettus leschenaultii and Cynopterus sphinx, cave-roosting and tree-roosting fruit bats, respectively. The optic centre processing the visual image, V1, appears more distinctly immunostaining in S. kuhlii and C. sphinx after 1 h of UV light stimuli while in H. armiger and R. leschenaultii, staining was no more distinct than in corresponding controls. Our immunohistochemical evidence supports differences in the distribution of cone-based UV vision in the order Chiroptera and supports our earlier postulate that due to possible sensory tradeoffs and roosting ecology, defects in the short wavelength opsin genes have resulted in loss of UV vision in CF but not in FM bats. In addition, fruit bats roosting in caves have lost UV vision but not those roosting in trees. Our results thus confirm that bats are a further mammalian taxon that has retained cone-based UV sensitivity in some species.     

Outcomes of co-infection by two potyviruses: implications for the evolution of manipulative strategies

Recent studies have documented effects of plant viruses on host plants that appear to enhance transmission by insect vectors. But, almost no empirical work has explored the implications of such apparent manipulation for interactions among co-infecting pathogens. We examined single and mixed infections of two potyviruses, watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV), that frequently co-occur in cucurbitaceae populations and share the same aphid vectors. We found that ZYMV isolates replicated at similar rates in single and mixed infections, whereas WMV strains accumulated to significantly lower levels in the presence of ZYMV. Furthermore, ZYMV induced changes in leaf colour and volatile emissions that enhanced aphid (Aphis gossypii) recruitment to infected plants. By contrast, WMV did not elicit strong effects on plant–aphid interactions. Nevertheless, WMV was still readily transmitted from mixed infections, despite fairing poorly in in-plant competition. These findings suggest that pathogen effects on host–vector interactions may well influence competition among co-infecting pathogens. For example, if non-manipulative pathogens benefit from the increased vector traffic elicited by manipulative competitors, their costs of competition may be mitigated to some extent. Conversely, the benefits of manipulation may be limited by free-rider effects in systems where there is strong competition among pathogens for host resources and/or access to vectors.     

Molecular ecology and phylogeography of the bent-wing bat complex (Miniopterus schreibersii) (Chiroptera: Vespertilionidae) in Asia Minor and adjacent regions

In this study we investigate population genetic structure and phylogeography of the bent-wing bat complex ( Miniopterus schreibersii ) in Asia Minor and adjacent regions. PCR amplification and sequencing of the first hypervariable domain of the mitochondrial control region were used to obtain the genetic data. Morphometric differentiation between lineages was analysed by comparing forearm lengths. We found two reciprocally monophyletic lineages within the M . schreibersii complex, identified as M.   s. schreibersii and M. s . pallidus . Distributions of the lineages were allopatric with a U-shaped suture zone passing through Central Anatolia. The suture zone separated coastal regions occupied by M.   s. schreibersii from inland, higher altitude regions occupied by M.   s. pallidus . The lineages showed a considerable sequence divergence of c . 9%, accompanied by a corresponding difference in forearm length. The presence of the genetically distinct lineages, with allopatric distribution and corresponding morphometric differences, probably reflects their long isolation during the ice-age in the Balkans and the Caspian/Caucasus refugia, followed subsequently by expansion into different habitats. Based on the present data, the lineages can be recognized as evolutionary significant units.     

The implications of intergenic polymorphism for major histocompatibility complex evolution

A systematic survey of six intergenic regions flanking the human HLA-B locus in eight haplotypes reveals the regions to be up to 20 times more polymorphic than the reported average degree of human neutral polymorphism. Furthermore, the extent of polymorphism is directly related to the proximity to the HLA-B locus. Apparently linkage to HLA-B locus alleles, which are under balancing selection, maintains the neutral polymorphism of adjacent regions. For these linked polymorphisms to persist, recombination in the 200-kb interval from HLA-B to TNF must occur at a low frequency. The high degree of polymorphism found distal to HLA-B suggests that recombination is uncommon on both sides of the HLA-B locus. The least-squares estimate is 0.15% per megabase with an estimated range from 0.02 to 0.54%. These findings place strong restrictions on possible recombinational mechanisms for the generation of diversity at the HLA-B.     

Biochemical systematics of the Savi's bat (Hypsugo savii) (Chiroptera: Vespertilionidae)

In order to assess the controversial systematic position of the Savi's bat (Hypsugo savii), 43 ves-pertilionid bats belonging to 10 species were analyzed by mean of isozyme electrophoresis. The results were interpreted in two ways: first, we found that the amount of genetic differentiation between Hypsugo and the true Pipistrellus (D # 0.719) is of the same magnitude as the mean distance which separates the other pipistrelloid genera (D = 0.738). Secondly, the cladogram based on these biochemical results confirms the splitting of these “pipistrelles”, as Hypsugo is more closely related to Vespertilio than to any other palearctic genus. The other species analyzed in this study group themselves in a different clade, including Pipistrellus, Eptesicus and Nyctalus. This phylogenetic interpretation presents a testable hypothesis, which could be confirmed by an analysis of other loci or other allied species.     

Reproductive biology and postnatal development in the tent-making bat Artibeus watsoni (Chiroptera: Phyllostomidae)

In this study we investigated the reproductive patterns and postnatal development in the tent-making bat Artibeus watsoni . We sampled two populations in the Golfito Wildlife Refuge and Corcovado National Park, south-western Costa Rica, from June 2003 to March 2005. Most females were pregnant during the months of January and June, and most were lactating in March and July, indicating that this species exhibits seasonal bimodal polyoestry, with the first parturition peak occurring in February–March and the second in June–July. Additionally, we observed a postpartum oestrus following the first parturition, but not after the second. Females entered oestrus again in November–December and had a gestation period of c . 3 months. A female-biased sex ratio of neonates was observed during the second parturition period, and young were born at 32 and 56% of their mothers' body mass and length of forearm, respectively. Adult proportions in length of forearm were attained faster than adult proportions in body mass, and sustained flight was only possible after 35 days of age, when pups had achieved 100 and 80% of adult length of forearm and body mass proportions, respectively. Weaning and roosting independence occurred when young were c . 30–40 days old, and young females appeared to remain close to their place of birth, at least for their first mating period, whereas adult males were never recaptured near their birth site. In addition, sexual maturity was reached in as little as 3 months in females born during the first parturition period, whereas females born during the second birth period in June–July seemed to reach maturity at 6 months of age. Our results show that A. watsoni belongs to the faster lane of the slow–fast continuum of life-history variation in bats, which may be attributed primarily to its roosting and feeding ecology.     

Karyotype relationships of six bat species (Chiroptera, Vespertilionidae) from China revealed by chromosome painting and G-banding comparison

The Vespertilionidae is the largest family in the order Chiroptera and has a worldwide distribution in the temperate and tropical regions. In order to further clarify the karyotype relationships at the lower taxonomic level in Vespertilionidae, genome-wide comparative maps have been constructed between Myotis myotis (MMY, 2n = 44) and six vesper bats from China: Myotis altarium (MAL, 2n = 44), Hypsugo pulveratus (HPU, 2n = 44), Nyctalus velutinus (NVE, 2n = 36), Tylonycteris robustula (TRO, 2n = 32), Tylonycteris sp. (TSP, 2n = 30)and Miniopterus fuliginosus (MFU, 2n = 46) by cross-species chromosome painting with a set of painting probes derived from flow-sorted chromosomes of Myotis myotis. Each Myotis myotis autosomal probe detected a single homologous chromosomal segment in the genomes of these six vesper bats except for MMY chromosome 3/4 paint which hybridized onto two chromosomes in the genome of M. fuliginosus. Our results show that Robertsonian translocation is the main mode of karyotype evolution in Vespertilionidae and that the addition of heterochromatic material also plays an important role in the karyotypic evolution of the genera Tylonycteris and Nyctalus. Two conserved syntenic associations (MMY9 + 23 and 18 + 19) could be the synapomorphic features for the genus Tylonycteris. The integration of our maps with the published maps has enabled us to deduce chromosomal homologies between human and these six vesper bats and provided new insight into the karyotype evolution of the family Vespertilionidae.     

An HRP study in the cat of pathways which may interconnect the two ventrobasal complexes

Possible direct or indirect connections between the two VB thalamic complexes were investigated using the HRP technique. Labelled cells were found ipsilaterally in the NCP and in NRT following injections n the VB complex and in the ipsilateral NRT and in contralateral NCP following injections in NCP. No labelling of contralateral VB complex was ever found. A pathway involving NRT and NCP is suggested to support the possibility of indirect connections between the two thalami and the functional implications of the described projections are discussed.     

Intron evolution: a statistical comparison of two models.

The two most frequently occurring explanations for the existence and distribution of introns in the genes of different species are: (1) introns are remnants of the original genetic material. (2) Introns were introduced during evolution. We construct mathematical models corresponding to these two explanations, and calculate the probabilities that the intron distribution in genes from different species coding for actin, alpha-tubulin, triosephosphate isomerase and superoxide dismutase are described by these models. In both models, the branch lengths as well as the structure of the corresponding evolutionary tree is taken into account. Every branch in the evolutionary tree is assumed to have its own individual rate of loss of introns for the first model and rate of gain of introns for the second model. These rate constants are estimated from the actual number of introns. Using the rate constants we stimulate the intron evolution and calculate the probabilities that the actual intron arrangements are produced. The results for actin and alpha-tubulin, which are the two genes we have the most data for, favor the model corresponding conjecture (1), i.e. the idea that introns are old. This contradicts the results from an earlier attempt to model intron evolution where almost the same data was used (Dibb & Newman, 1989, EMBO J. 8, 2015-2021).     

Gravity: one of the driving forces for evolution

Mechanical load is 10(3) larger for land-living than for water-living organisms. As a consequence, antigravitational material in form of compound materials like lignified cell walls in plants and mineralised bones in animals occurs in land-living organisms preferentially. Besides cellulose, pectic substances of plant cell walls seem to function as antigravitational material in early phases of plant evolution and development. A testable hypothesis including vesicular recycling processes into the tensegrity concept is proposed for both sensing of gravitational force and responding by production of antigravitational material at the cellular level.