The social organization of most mammals is characterized by female philopatry and male dispersal. Such sex-biased dispersal can cause the genetic structure of populations to di¡er between the maternally inherited mitochondrial DNA (mtDNA) and the bi-parental nuclear genome. Here we report on the global genetic structure of oceanic populations of the sperm whale, one of the most widely distributed mammalian species. Groups of females and juveniles are mainly found at low latitudes, while males reach polar waters, returning to tropical and subtropical waters to breed. In comparisons between oceans, we did not ¢nd signi¢cant heterogeneity in allele frequencies of microsatellite loci (exact test; p 0.23). Estimates of G ST 0.001 and R ST 0.005 also indicated negligible if any nuclear DNA di¡erentiation. We have previously reported signi¢cant di¡erentiation between oceans in mtDNA sequences. These contrasting patterns suggest that interoceanic movements have been more prevalent among males than among females, consistent with observations of females being the philopatric sex and having a more limited latitudinal distribution than males. Consequently, the typical mammalian dispersal pattern may have operated on a global scale in sperm whales.

The genetic variability and population structure of worldwide populations of the sperm whale was investigated by sequence analysis of the ¢rst 5'L 330 base pairs in the mitochondrial DNA (mtDNA) control region. The study included a total of 231 individuals from three major oceanic regions, the North Atlantic, the North Paci¢c and the Southern Hemisphere. Fifteen segregating nucleotide sites de¢ned 16 mtDNA haplotypes (lineages). The most common mtDNA types were present in more than one oceanic region, whereas ocean-speci¢c types were rare. Analyses of heterogeneity of mtDNA type frequencies between oceans indicated moderate (G ST 0.03) but statistically signi¢cant (p 0.0007) genetic di¡erentiation on a global scale. In addition, strong genetic di¡erentiation was found between potential social groups (G ST 0.3^0.6), indicating matrilineal relatedness within groups. The global nucleotide diversity was quite low (p 0.004), implying a recent common mtDNA ancestry (5100 000 years ago) and a young global population structure. However, within this time period, female dispersal has apparently been limited enough to allow the development of global mtDNA di¡erentiation. The results are consistent with those from observational studies and whaling data indicating stable social a¤liations, some degree of area ¢delity and latitudinal range limitations in groups of females and juveniles.

The population status of the harbour porpoise (Phocoena phocoena) in the Baltic area has been a continuous matter of debate. Here we present the by far most comprehensive genetic population structure assessment to date for this region, both with regard to geographic coverage and sample size: 497 porpoise samples from North Sea, Skagerrak, Kattegat, Belt Sea, and Inner Baltic Sea were sequenced at the mitochondrial Control Region and 305 of these specimens were typed at 15 polymorphic microsatellite loci. Samples were stratified according to sample type (stranding vs. by-caught), sex, and season (breeding vs. non-breeding season). Our data provide ample evidence for a population split between the Skagerrak and the Belt Sea, with a transition zone in the Kattegat area. Among other measures, this was particularly visible in significant frequency shifts of the most abundant mitochondrial haplotypes. A particular haplotype almost absent in the North Sea was the most abundant in Belt Sea and Inner Baltic Sea. Microsatellites yielded a similar pattern (i.e., turnover in occurrence of clusters identified by STRUCTURE). Moreover, a highly significant association between microsatellite assignment and unlinked mitochondrial haplotypes further indicates a split between North Sea and Baltic porpoises. For the Inner Baltic Sea, we consistently recovered a small, but significant separation from the Belt Sea population. Despite recent arguments that separation should exceed a predefined threshold before populations shall be managed separately, we argue in favour of precautionary acknowledging the Inner Baltic porpoises as a separate management unit, which should receive particular attention, as it is threatened by various factors, in particular local fishery measures. © Springer Science+Business Media B.V. 2009

Associations among female sperm whales, Physeter macrocephalus, and their dependent offspring, off the Galfipagos Islands were studied between 1985 and 1989. The whales were found in groups containing about 23 individuals, with each individual having approximately 12 constant (over years) companions. These permanent units associated with one another for periods of ~6.5 days, although the rate and duration of these associations seemed to vary between years, perhaps because of differences in the food supply. The principal function of the closed units may be care of the offspring, and units in the same general area may derive benefit from feeding in a coordinated manner.

The mitochondrial DNA (mtDNA) control region was sequenced in 37 sperm whales from a large part of the global range of the species. Nucleotide diversity was several-fold lower than that reported for control regions of abundant and outbred mammals, but similar to that for populations known to have experienced bottlenecks. Relative neck tests did not suggest that the low diversity is due to a lower substitution rate in sperm whale mtDNA. Rather, it is more likely that demographic factors have reduced diversity. The pattern of nucleotide substitutions was examined by cladistic methods, facilitated by the apparent monophyly of lineages from the Southern Hemisphere, as defined by a single base pair deletion. Substitutions were nonrandom in nature, confined to a few "hot spots," and parallel substitutions constituted a majority of the inferred changes. The substitution pattern fitted a negative binomial distribution better than a Poisson distribution, and the bias in number of substitutions among sites was considerably higher than previously reported for the mtDNA control region of any species. A novel method of estimating time since common ancestry was developed, which utilizes the transition/transversion ratio R and the number of substitutions inferred from a parsimony analysis. Using this method, we estimated the age of sperm whale mtDNA diversity to be about 6,000-25,000 years, and when the uncertainty of R was accounted for, a range of about 1,000-100,000 years was obtained.

As for many other regions, environmental and biodiversity monitoring of the brackish Baltic Sea suffers from low species resolution for several taxa. One such case is the benthic larvae of midges Chironomidae (Diptera), which are estimated to constitute about 30% of the macrozoobenthos species of the Baltic Sea and are important indicators of environmental quality. We assessed the usefulness of COI (cytochrome oxidase I) gene barcoding to improve species resolution and its potential for implementation in monitoring programmes. Neighbour-Joining, Maximum parsimony and Bayesian-inference analyses all provided high congruency with morphological analyses of adult males for almost all 42 species studied. Barcoding was helpful to elucidate some cases of taxonomical difficulties, such as synonyms. In contrast to the high identification accuracy when using our local database, there were a number of cases where matching with GenBank and BOLD provided puzzling results. For reliable species identification at least 15-30 specimens from 5-10 well-distributed sites within the geographical range of the species might be needed in a database to adequately cover the intraspecific variability of chironomids. Implementation of DNA barcoding, as applied here, in monitoring would result in an increase from at present less than 10% to more than 90% successful chironomid species identification of Baltic Sea benthic samples, as it also would for many nearby lakes. Routine monitoring of benthic environmental samples based on Next-Generation sequencing techniques would provide a cost effective way to obtain a taxonomically much more complete assessment of environmental quality and biodiversity, as required by EU directives and national legislation.

The structure of the population of female and immature sperm whales (Physeter macrocephalus) in the region of the Galápagos Islands was studied using individual photographic identifications of 1285 animals collected between 1985 and 1989. Population parameters were estimated using a maximum-likelihood mark–recapture estimate permitting emigration from the study area in which identifications are collected and then reimmigration back into it. Because permanent associations among whales violated assumptions of independence, confidence intervals for the estimates were constructed using Monte-Carlo population simulation. The analysis suggested that there is a population of very approximately 200 whales in the study area around the islands at any time. These were part of a larger population numbering between 2600 and 5300 individuals (95% confidence interval). An average of 39–94% (95% confidence interval) of the whales left the study area in any month, with a similar number immigrating.

Killer whales (Orcinus orca) have group‐specific call repertoires that can be used to track groups and populations using passive acoustic monitoring. To provide a detailed description of the Icelandic killer whale repertoire and its variation, we analyzed acoustic data collected in five locations between 1985 and 2016. Calls were classified manually, and CART and random forest analyses were employed to validate the manual classification. A total of 91 call categories (including call types and subtypes) were defined. Most call categories were recorded in more than one location, with the highest proportion shared between herring grounds in Vestmannaeyjar (South) and Breiðafjörður (West). However, both locations included call categories that were not recorded elsewhere in Iceland. Recordings from past herring wintering grounds in eastern Iceland included few call categories that matched other locations. Sample sizes from Reykjanes (Southwest) and Skjálfandi (North) were small and did not include unique call categories. The relative occurrence of call categories in Vestmannaeyjar changed little over a 14‐year period (2002–2016), although shorter‐term changes between years were observed that appeared to correlate to changes in individuals identified. This comparison of acoustic repertoires provides valuable information on the social structure and movement patterns of herring‐eating killer whales around Iceland.