Distinctive Paleo-Indian Migration Routes from Beringia Marked by Two Rare mtDNA Haplogroups

Background: It is widely accepted that the ancestors of Native Americans arrived in the New World via Beringia approximately 10 to 30 thousand years ago (kya). However, the arrival time(s), number of expansion events, and migration routes into the Western

The sequence and de novo assembly of the giant panda genome

Using next-generation sequencing technology alone, we have successfully generated and assembled a draft sequence of the giant panda genome. The assembled contigs (2.25 gigabases (Gb)) cover approximately 94% of the whole genome, and the remaining gaps (0.05 Gb) seem to contain carnivore-specific repeats and tandem repeats. Comparisons with the dog and human showed that the panda genome has a lower divergence rate. The assessment of panda genes potentially underlying some of its unique traits indicated that its bamboo diet might be more dependent on its gut microbiome than its own genetic composition. We also identified more than 2.7 million heterozygous single nucleotide polymorphisms in the diploid genome. Our data and analyses provide a foundation for promoting mammalian genetic research, and demonstrate the feasibility for using next-generation sequencing technologies for accurate, cost-effective and rapid de novo assembly of large eukaryotic genomes.

Boundary Characterization Experiment Series Overview

Ocean acoustic propagation and reverberation in continental shelf regions is often controlled by the seabed and sea surface boundaries. A series of three multi-national and multi-disciplinary experiments was conducted between 2000-2002 to identify and measure key ocean boundary characteristics. The frequency range of interest was nominally 500-5000 Hz with the main focus on the seabed, which is generally considered as the boundary of greatest importance and least understood. Two of the experiments were conducted in the Mediterranean in the Strait of Sicily and one experiment in the North Atlantic with sites on the outer New Jersey Shelf (STRATAFORM area) and on the Scotian Shelf. Measurements included seabed reflection, seabed, surface, and biologic scattering, propagation, reverberation, and ambient noise along with supporting oceanographic, geologic, and geophysical data. This paper is primarily intended to provide an overview of the experiments and the strategies that linked the various measurements together, with detailed experiment results contained in various papers in this volume and other sources

角百灵和小云雀的孵化行为

鸟类的个体发育是在双亲、雏鸟及巢组成的一种特殊环境中完成的，稳定的热环境是它们完成孵化和雏鸟生长发育的必要条件（White et al.，1974；Purdue，1976；Ellis，1982；Haftorn，1983；Morton et al.，1985；Schnace et al.，1991；Vatnick et al.，1998；张晓爱等，1995）。因此亲鸟的伴巢行为及时间是指亲鸟在繁殖期间，为筑巢、防御、抱卵、孵雏及递食而出现在巢中或附近的所有行为（Oppenhaim，1972）。亲鸟拌巢的时间分配与巢环境有密切关系，已有大量的报道（如Purdue，1976；Ellis, 1982；Schnace et al., 1991；张晓爱等，1995）。张晓爱等（1995）比较了高寒草甸地区的地面、灌丛及洞穴3种不同营巢类型亲鸟的伴巢时间分配模式，但是对亲缘关系较近，营巢生境相同鸟类之间的伴巢时间分配模式，以及坐巢行为与巢环境之间关系没有报道，国外对这方面的报道也甚少。本项研究选择高寒草甸的两种百灵科鸟：角百灵（Eremophila alpestris）和小云雀（Alauda gulgula）作为研究对象来比较亲鸟在卵化期坐巢行为与巢址微环境的关系，对研究鸟类繁殖行为与环境关系及从生活史进化角度研究相似种的共存机制提供理论依据。