Asymmetric dispersal of southern bull‐kelp (Durvillaea antarctica) adults in coastal New Zealand: testing an oceanographic hypothesis

Coastal populations are often connected by unidirectional current systems, but the biological effects of such asymmetric oceanographic connectivity remain relatively unstudied. We used mtDNA analysis to determine the phylogeographic origins of beach‐cast bull‐kelp (Durvillaea antarctica) adults in the Canterbury Bight, a 180 km coastal region devoid of rocky‐reef habitat in southern New Zealand. A multi‐year, quantitative analysis supports the oceanographically derived hypothesis of asymmetric dispersal mediated by the north‐flowing Southland Current. Specifically, 92% of beach‐cast specimens examined had originated south of the Bight, many drifting north for hundreds of kilometres, and some traversing at least 500 km of ocean from subantarctic sources. In contrast, only 8% of specimens had dispersed south against the prevailing current, and these counter‐current dispersers likely travelled relatively small distances (tens of kilometres). These data show that oceanographic connectivity models can provide robust estimates of passive biological dispersal, even for highly buoyant taxa. The results also indicate that there are no oceanographic barriers to kelp dispersal across the Canterbury Bight, indicating that other ecological factors explain the phylogeographic disjunction across this kelp‐free zone. The large number of long‐distance dispersal events detected suggests drifting macroalgae have potential to facilitate ongoing connectivity between otherwise isolated benthic populations.     

Spatial patterns of genetic structure among populations of a stone‐cased caddis (Trichoptera: Tasimiidae) in south‐east Queensland,Australia

1. Gene flow and dispersal among populations of a stone‐cased caddis (Tasimiidae: Tasimia palpata) were estimated indirectly using a 460 bp region of the cytochrome oxidase I gene of mitochondrial DNA. 2. There was no significant differentiation at the largest spatial scale (between catchments) and no correlation between genetic distance and geographic distance. These results are consistent with widespread adult dispersal. 3. Conversely, significant genetic differentiation was detected at the smallest spatial scale examined (among reaches within streams). This pattern was primarily because of significant F_ST values in a single stream (Bundaroo Creek). 4. Bundaroo Creek also had the lowest mean number of haplotypes per population (n = 7) suggesting that a limited number of females may be responsible for recruitment at these sites. Significant F_ST's at the reach scale may be a result of this ‘patchy’ recruitment. However, additional evidence regarding the long‐range dispersal ability and fecundity of T. palpata females is needed to test this hypothesis fully.     

Genetic diversity and historical population structure in the New Zealand mayfly Acanthophlebia cruentata

1. Nucleotide sequences of a 280 base pair region of the cytochrome b gene were used to assess genetic diversity and to infer population histories in the New Zealand mayfly Acanthophlebia cruentata. 2. A hierarchial examination of populations from 19 streams at different spatial scales in the central and northern North Island of New Zealand found 34 haplotypes. A common haplotype was found in all central region streams and unique haplotypes in northern streams. Several central streams had region specific haplotypes with genetically differentiated populations at the 70–100 km scale. 3. Haplotype diversity was high (0.53–0.8) at most sites, but low (0–0.22) in some central sites. amova analyses found significant genetic diversity among regions (69%) and among catchments (58%). Most population pairwise F_ST tests were significant, with non‐significant pairwise tests among sites in the central region and pairs of sites between neighbouring streams. 4. The levels of sequence divergence are interpreted as the result of Pleistocene divergence in multiple refugia, leading to the evolution of regionally unique haplotypes. The low diversity in some central region populations may result from recent colonisation following local extinctions, associated with volcanic events.     

叶螨线粒体COI基因中央区段的PCR扩增

根据二点叶螨线粒体ＣＯＩ基因序列设计１对ＰＣＲ引物,对叶螨科不同种属的线粒体ＣＯＩ基因中央区段进行了ＰＣＲ扩增,结果表明该对引物能成功扩增叶螨科７属９种叶螨的约３４０ｂｐ的同源片段,由于叶螨ＤＮＡ序列资料非常有限,扩大引物的使用范围成为快速获得物特定基因序列的有效途径,研究结果使根据叶螨线粒体ＣＯＩ基因序列信息探索其系统演化成为可能,另外,还对模板ＤＮＡ分离方法进行了优化。     

A Gene Encoding a Cytochrome c Oxidase-Like Protein Is Located Closely to the Cytochrome c-553 Gene in the Anaerobic Bacterium,Desulfovibrio vulgaris (Miyazaki F)

The gene encoding cytochrome c-553 from Desulfovibrio vulgaris (Miyazaki F) was cloned using a synthetic oligodeoxyribonucleotide probe. The nucleotide sequence indicated that cytochrome c-553 was synthesized as a precursor protein with an NH₂-terminal signal sequence of 23 residues. In the cloned DNA fragment, there are three other open reading frames whose products have 191, 157, 541 amino acid residues, respectively. The putative ORF-4 product is highly homologous with the cytochrome c oxidase subunit I from various organisms.     

青蟹线粒体COI假基因的分离和特征分析

线粒体DNA标记在遗传结构和系统进化研究中得到广泛应用,然而核假基因的存在对此有很大威胁。本文以中国东南沿海的青蟹(Scylla paramamosain)为研究对象,利用线粒体COI基因的通用引物和特异性引物进行扩增,分别得到34个假基因（nuclear mitochondrial pseudogenes, Numts）和5个线粒体COI基因序列。在所获得的34个假基因中共定义了29种单倍型,根据序列的相似度,这些假基因可以分为2类,每类假基因都有各自保守的核苷酸序列。第Ⅰ类假基因存在2处插入序列和1处8 bp的缺失序列,这些位点导致了整个阅读框的移位;在第Ⅱ类假基因和5个线粒体COI序列中只有碱基替换,未发现插入和缺失序列。实验结果分析表明,这两类假基因分别代表了2次核整合事件,即核转移事件的最低值。研究结果提示了