Polymorphism of blood plasma proteins in theAnser andBranta genera

An electrophoretical analysis of blood plasma proteins of eightAnser and twoBranta species was performed. Ten polymorphic proteins in blood plasma pattern were distinguished and described: four prealbumin proteins, albumin, three postalbumin proteins, transferrin, and a single posttransferrin protein. Genus-specific and species-specific variants of Pr-1, Al, Pa-3, Pa-X, and Tf proteins were found. The species ofBranta differed inPr-1,Pa-3,Pa-X, andTf loci. TheAnser species differed, apparently, in allele frequencies of described gene loci. A single species-specific protein marker was found in swan geese only. The electrophoretic mobilities of Pr-1, TfB, and PtfA, B, and C were similar for several species ofAnser andBranta genera.     

Close relatedness between mitochondrial DNA from seven Anser goose species

The phylogenetic relationships of seven goose species and two of the subspecies representing the genus Anser were studied by approximately 1180 bp of mitochondrial DNA tRNAglu, control region and tRNAphe sequences. Despite obvious morphological and behavioural affinities among the species, their evolutionary relationships have not been studied previously. The small amount of genetic differentiation observed in the mitochondrial DNA indicates an extremely close evolutionary relationship between the Anser species. The sequence divergences between the species (0.9–5.5%) are among the lowest reported for avian species with speciation events of Anser geese dating to late Pliocene and Pleistocene. The species grouped into four mtDNA lineages: (1) snow and Ross’ goose, (2) greylag goose, (3) white‐fronted goose, and (4) bean, pink‐footed and lesser white‐fronted goose. The phylogenetic relationships of the most closely related species, bean, pink‐footed and lesser white‐fronted goose, indicate a period of rapid cladogenesis. The poor agreement between morphological relationships and the phylogenetic relationships indicated by mtDNA sequences implies that either ancestral polymorphism and lineage sorting, hybridization and introgression or convergent evolution has been involved.     

Evolutionary distances in hawaiian drosophila measured by DNA reassociation

Summary Comparisons of the sequence divergence of three species of Hawaiian Drosophila have been made by hybridization of single-copy tracer DNA of each of the species with driver DNA from each species, and measurement of the average melting temperature (Tma) in a chaotropic solvent (2.4 M tetraethylammonium chloride) which minimizes differences due to base composition. Correction was made for the length of hybrid duplex regions to obtain the reduction in thermal stability due to divergence.An accuracy of ± 0.2°C was achieved and the mean reduction in Tm for hybridization betweenD. heteroneura andD. silvestris (found only on the island of Hawaii) was 0.55°C and betweenD. picticornis, found only on the island of Kauai, and the other two species was 2.13°C. The rate of DNA change is estimated to be between 0.2 and 0.4%/My by assuming that theD. heteroneura-D. silvestris divergence occurred 0.8 My ago and the divergence between these species andD. picticornis between 4 and 6 My ago.The general single copy DNA sequence divergence appears to be very much greater than the minimal coding region sequence divergence previously estimated from allozyme studies.     

Evolutionary conservation of DNA sequences expressed in sea urchin eggs and early embryos

Summary DNA sequence divergence measurements indicate thatStrongylocentrotus franciscanus is more distinct fromS. purpuratus andS. drobachiensis than these two species are from each other, in agreement with paleontological and morphological evidence. The evolutionary divergence of several classes of expressed DNA sequences was compared with that of total single-copy DNA. BetweenS. franciscanus andS. purpuratus the divergence of cDNA made from gastrula cytoplasmic poly(A)⁺ RNA is about half that of total single-copy DNA. Similar results were obtained for cDNA made from unfertilized egg poly(A)⁺ RNA. In contrast, sequences expressed in gastrula nuclear RNA have diverged almost as much as total single-copy DNA.     

Mitochondrial pseudogenes and phyletic relationships ofCebuella andCallithrix (Platyrrhini, primates)

Two cytochromeb pseudogenes were isolated from PCR amplified products ofCebuella pygmaea DNA. These sequences showed insertions and deletions when compared to paralogous mitochondrial sequence regions of several primates. Phylogenetic analyses indicated that an ancestral pseudogene originated sometime before the divergence ofCebuella andCallithrix and that this sequence was later duplicated some 5.6 million years ago. Parsimony and distance analyses indicated thatCebuella pygmaea andCallithrix species of theargentata group were more closely related to one another than any of them was toCallithrix species of thejacchus group, in agreement with previous analyses based on nuclear genes and karyotypic data. These findings also indicated thatCallithrix is a paraphyletic genus, in agreement with previous propositions thatCebuella should be included within the genusCallithrix.     

DNA/DNA Hybridization studies among six endemic Hawaiian Drosophila species

The nucleotide-sequence homology and divergence of six endemic Hawaiian Drosophila species have been studied by means of DNA/DNA hybridization experiments, using the fractionated unique and moderately repetitive sequences. The data indicate that the extent of homology between the nonrepetitive DNA sequences of D. crucigera, D. pilimana, D. engyochracea, D. silvarentis and D. picticornis confirms the taxonomic relationship established through cytological evidence. The average rate of divergence of nonrepetitive DNA sequences among Hawaiian Drosophila species is approximately 2.75 to 3.75% per million years. This value is much higher than that found among other species when divergence time is estimated on an absolute time base.     

Evolution of single-copy DNA and the ADH gene in seven drosophilids

Summary Single-copy DNA was isolated fromDrosophila melanogaster and hybridized with total genomic DNA ofD. melanogaster, D. mauritiana, D. simulans, D. pseudoobscura, D. willistoni, D. hydei andD. virilis. The duplexes were thermally eluted from hydroxyapatite and the data used to assess the relatedness of each species toD. melanogaster. The general pattern of relatedness was similar to that predicted by morphological methods but with some notable exceptions. The rate of nucleotide substitution was estimated to be greater than 0.66% of bases per million years. An unexpected, rapidly evolving component ofD. melanogaster single-copy DNA was identified. The relatedness of these species was also studied with respect to the gene coding for alcohol dehydrogenase (ADH). The ADH gene, previously cloned fromD. melanogaster (Goldberg 1980), was hybridized with Southern blots of genomic digests of the seven species. The intensity and position of the hybridizing bands suggest the amount of divergence of the gene. Divergence was quantitated by reassociation of a fragment of the cloned ADH gene with total DNA of the seven drosophilids and thermal elution of the resultant duplexes from hydroxyapatite. The ADH gene was isolated from genomic clone libraries ofD. melanogaster, D. simulans andD. mauritiana and further studied by comparison of position of restriction sites. Species relationships deduced from comparison of total single-copy DNA and the ADH gene were consistent, demonstrating that a single gene can reflect divergence of the entire genome.     

Single copy DNA and structural gene sequence relationships among four sea urchin species

Measurements of the divergence of single copy DNA sequences among four sea urchin species are presented. At a standard criterion for reassociation (0.12 M phosphate buffer, 60° C, hydroxyapatite binding) we observe the following extents of reaction and reductions in thermal stability for single copy DNA reassociation between Strongylocentrotus purpuratus tracer and heterologous driver DNA: S. dröbachiensis 68% and 2.5°C; S. franciscanus 51% and 3.5° C; Lytechinus pictus 12% and 7.5° C. The implied extents of sequence relatedness are consistent with the phylogenetic relationships of these species. The rate of single copy sequence divergence in the evolutionary lines leading to the Strongylocentrotus species is estimated to be 0.06–0.35% per million years. The rate of divergence of total single copy sequence has been compared to that of structural gene sequences represented in S. purpuratus gastrula polysomal messenger RNA. When closely related species, S. purpuratus and S. franciscanus, are compared, these polysomal sequences are found to diverge at a lower rate than does the total single copy sequence. For two very distantly related species, S. purpuratus and L. pictus, a small fraction of the single copy DNA sequence is probably conserved. These conserved sequences are not enriched in their content of structural gene sequences.Also staff member, Carnegie Institution of Washington, Washington, D.C. 20015     

The complete nucleotide sequence of the mitochondrial DNA of the fin whale,Balaenoptera physalus

Summary The composition of the mitochondrial DNA (mtDNA) of the fin whale,Balaenoptera physalus, was determined. The length of the molecule is 16,398 bp, and its organization conforms with that of other mammals. The general similarity between the mtDNA of the fin whale and the cow is greater than the similarity between the fin whale and other species (human, mouse, rat) in which the composition of the entire molecule has been described. The D-loop region of the mtDNA of the fin whale is 81% identical to the D-loop of dolphin DNA, and the central portion of the D-loop is similar to the bovine D-loop. The accumulation of transversions and gaps in the 12S and 16S rRNA genes was assessed by comparing the fin whale, cow, and human. The sequence difference between human and the whale and human and the cow was at the same level, indicating that the rate of evolution of the mtDNA rRNA genes is about the same in artiodactyls and cetaceans. In the 12S rRNA gene an accumulation rate of 0.05% per million years places the separation of cetaceans and artiodactyls at about 55 million years ago. The corresponding figure for human and either the whale or the cow is about 80 million years. In the 16S rRNA gene a 0.08% accumulation rate of transversions and gaps per million years yields concurring figures. A comparison between the cytochromeb gene of the fin whale and cytochromeb sequences in the literature, including dolphin (Stenella) sequences, identified the cetaceans as monophyletic and the artiodactyls as their closest relatives. The comparison between the cytochromeb sequences of the fin whale andStenella showed that differences in codon positions one or two were frequently associated with a change in another codon position.     

Location and agricultural practices influence spring use of harvested cornfields by cranes and geese in Nebraska

Millions of ducks, geese, and sandhill cranes (Grus canadensis; hereafter cranes) stop in the Central Platte River Valley (CPRV) of Nebraska to store nutrients for migration and reproduction by consuming corn remaining in fields after harvest. We examined factors that influence use of cornfields by cranes and geese (all mid-continent species combined; e.g., Anser, Chen, and Branta spp.) because it is a key step to efficient conservation planning aimed at ensuring that adequate food resources are available to migratory birds stopping in the CPRV. Distance to night-time roost site, segment of the CPRV (west to east), and agricultural practices (post-harvest treatment of cornfields: idle, grazed, mulched, mulched and grazed, and tilled) were the most important and influential variables in our models for geese and cranes. Probability of cornfield use by geese and cranes decreased with increasing distance from the closest potential roosting site. The use of cornfields by geese increased with the density of corn present there during the early migration period, but field use by cranes appeared not to be influenced by early migration corn density. However, probability of cornfield use by cranes did increase with the amount of wet grassland habitat within 4.8 km of the field. Geese were most likely to use fields that were tilled and least likely to use fields that were mulched and grazed. Cranes were most likely to use fields that were mulched and least likely to use fields that were tilled, but grazing appeared not to influence the likelihood of field use by cranes. Geese were more likely to use cornfields in western segments of the CPRV, but cranes were more likely to use cornfields in eastern segments. Our data suggest that managers could favor crane use of fields and reduce direct competition with geese by reducing fall and spring tilling and increasing mulching. Moreover, crane conservation efforts would be most beneficial if they were focused in the eastern portions of the CPRV and in fields as close as possible to both known roosting and large amounts of wet grassland habitats. © 2011 The Wildlife Society.