The harbor seal (Phoca vitulina) has one of the broadest geographic distributions of any pinniped, stretching from the east Baltic, west across the Atlantic and Pacific Oceans to southern Japan. Although individuals may travel several hundred kilometers on annual feeding migrations, harbor seals are generally believed to be philopatric, returning to the same areas each year to breed. Consequently, seals from different areas are likely to be genetically differentiated, with levels of genetic divergence increasing with distance. Differentiation may also be caused by long-standing topographic barriers such as the polar sea ice. We analyzed samples of 227 harbor seals from 24 localities and defined 34 genotypes based on 435 bp of control region sequence. Phylogenetic analysis and analysis of molecular variance showed that populations in the Atlantic and Pacific Oceans and east and west coast populations of these oceans are significantly differentiated. Within these four regions, populations that are geographically farthest apart generally are the most differentiated and often do not share genotypes or differ in genotype frequency. The average corrected sequence divergence between populations in the Atlantic and Pacific Oceans is 3.28% +/- 0.38% and those among populations within each of these oceans are 0.75% +/- 0.69% and 1.19% +/- 0.65%, respectively. Our results suggest that harbor seals are regionally philopatric, on the scale of several hundred kilometers. However, genetic discontinuities may exist, even between neighboring populations such as those on the Scottish and east English coasts or the east and west Baltic. The mitochondrial data are consistent with an ancient isolation of populations in both oceans, due to the development of polar sea ice. In the Atlantic and Pacific, populations appear to have been colonized from west to east with the European populations showing the most recent common ancestry. We suggest the recent ancestry of European seal populations may reflect recolonization from Ice Age refugia after the last glaciation.

The origins of South America's domestic alpaca and llama remain controversial due to hybridization, near extirpation during the Spanish conquest and di¤culties in archaeological interpretation. Traditionally, the ancestry of both forms is attributed to the guanaco, while the vicu·a is assumed never to have been domesticated. Recent research has, however, linked the alpaca to the vicu·a, dating domestication to 6000^7000 years before present in the Peruvian Andes. Here, we examine in detail the genetic relationships between the South American camelids in order to determine the origins of the domestic forms, using mitochondrial (mt) and microsatellite DNA. MtDNA analysis places 80% of llama and alpaca sequences in the guanaco lineage, with those possessing vicu·a mtDNA being nearly all alpaca or alpaca^vicu·a hybrids. We also examined four microsatellites in wild known-provenance vicu·a and guanaco, including two loci with non-overlapping allele size ranges in the wild species. In contrast to the mtDNA, these markers show high genetic similarity between alpaca and vicu·a, and between llama and guanaco, although bidirectional hybridization is also revealed. Finally, combined marker analysis on a subset of samples con¢rms the microsatellite interpretation and suggests that the alpaca is descended from the vicu·a, and should be reclassi¢ed as Vicugna pacos. This result has major implications for the future management of wild and domestic camelids in South America.

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We report the first molecular evolutionary analysis of the family Camelidae by analysing the full DNA sequence of the mitochondrial cytochrome b gene. Estimates for the time of divergence of the Old World (Camelini) and New World (Lamini) tribes obtained from sequence data are in agreement with those derived from the fossil record. The DNA sequence data were also used to test current hypotheses concerning the ancestors of the domesticated llama and alpaca. The results show that hybridization has occurred in the ancestry of both domesticated camelids, obscuring the origin of the domestic species.

We have investigated the changes in the concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the hypothalamus-preoptic area (HPOA) and midbrain raphe (MR) region of male and female rats throughout development. No sex differences were found in the concentrations of the indoleamines in either of the areas investigated at any stage of development. The 5-HIAA/5-HT molar ratio was maximal at 4 days of age in both the HPOA and MR. A small but significant sex difference in the 5-HIAA/5-HT ratio occurred in the HPOA (higher in males) but not in the MR at 40 days of age, and the ratio was significantly greater in 80-day-old female rats in the HPOA but not MR. Studies using NSD 1015 to block the conversion of 5-hydroxytryptophan to 5-HT showed that a higher rate of 5-HT synthesis occurred in the HPOA of 80-day-old rats compared with the neonatal HPOA and that in 80-day-old rats the rate of 5-HT synthesis was significantly higher in females. These results show that endogenous steroids do not affect the activity of serotoninergic neurons in the HPOA or MR either during or immediately after the critical period of sexual differentiation. In addition, the results from the NSD 1015 experiments show that the high 5-HIAA/5-HT ratio found in neonates does not involve a higher rate of 5-HT synthesis than that in adult rats.