Ecological,morphological and genetic divergence of sympatric North Atlantic killer whale populations

Ecological divergence has a central role in speciation and is therefore an important source of biodiversity. Studying the micro‐evolutionary processes of ecological diversification at its early stages provides an opportunity for investigating the causative mechanisms and ecological conditions promoting divergence. Here we use morphological traits, nitrogen stable isotope ratios and tooth wear to characterize two disparate types of North Atlantic killer whale. We find a highly specialist type, which reaches up to 8.5 m in length and a generalist type which reaches up to 6.6 m in length. There is a single fixed genetic difference in the mtDNA control region between these types, indicating integrity of groupings and a shallow divergence. Phylogenetic analysis indicates this divergence is independent of similar ecological divergences in the Pacific and Antarctic. Niche‐width in the generalist type is more strongly influenced by between‐individual variation rather than within‐individual variation in the composition of the diet. This first step to divergent specialization on different ecological resources provides a rare example of the ecological conditions at the early stages of adaptive radiation.     

Ancient DNA reveals traces of Iberian Neolithic and Bronze Age lineages in modern Iberian horses

Multiple geographical regions have been proposed for the domestication of Equus caballus . It has been suggested, based on zooarchaeological and genetic analyses that wild horses from the Iberian Peninsula were involved in the process, and the overrepresentation of mitochondrial D1 cluster in modern Iberian horses supports this suggestion. To test this hypothesis, we analysed mitochondrial DNA from 22 ancient Iberian horse remains belonging to the Neolithic, the Bronze Age and the Middle Ages, against previously published sequences. Only the medieval Iberian sequence appeared in the D1 group. Neolithic and Bronze Age sequences grouped in other clusters, one of which (Lusitano group C) is exclusively represented by modern horses of Iberian origin. Moreover, Bronze Age Iberian sequences displayed the lowest nucleotide diversity values when compared with modern horses, ancient wild horses and other ancient domesticates using nonparametric bootstrapping analyses. We conclude that the excessive clustering of Bronze Age horses in the Lusitano group C, the observed nucleotide diversity and the local continuity from wild Neolithic Iberian to modern Iberian horses, could be explained by the use of local wild mares during an early Iberian domestication or restocking event, whereas the D1 group probably was introduced into Iberia in later historical times.     

Ancient DNA sequences point to a large loss of mitochondrial genetic diversity in the saiga antelope (Saiga tatarica) since the Pleistocene

Prior to the Holocene, the range of the saiga antelope (Saiga tatarica) spanned from France to the Northwest Territories of Canada. Although its distribution subsequently contracted to the steppes of Central Asia, historical records indicate that it remained extremely abundant until the end of the Soviet Union, after which its populations were reduced by over 95%. We have analysed the mitochondrial control region sequence variation of 27 ancient and 38 modern specimens, to assay how the species’ genetic diversity has changed since the Pleistocene. Phylogenetic analyses reveal the existence of two well‐supported, and clearly distinct, clades of saiga. The first, spanning a time range from >49 500 ¹⁴C ybp to the present, comprises all the modern specimens and ancient samples from the Northern Urals, Middle Urals and Northeast Yakutia. The second clade is exclusive to the Northern Urals and includes samples dating from between 40 400 to 10 250 ¹⁴C ybp. Current genetic diversity is much lower than that present during the Pleistocene, an observation that data modelling using serial coalescent indicates cannot be explained by genetic drift in a population of constant size. Approximate Bayesian Computation analyses show the observed data is more compatible with a drastic population size reduction (c. 66–77%) following either a demographic bottleneck in the course of the Holocene or late Pleistocene, or a geographic fragmentation (followed by local extinction of one subpopulation) at the Holocene/Pleistocene transition.     

Der Arillus der tertiären Zingiberacee

Arillate seeds of Spirematospermum wetzleri (Heer) Chandler (Zingiberaceae) are described from the Fasterholt Miocene locality in Denmark, and five other European Tertiary localities. Investigations made involving the use of a scanning electron microscope showed a good correspondence between the aril of Spirematospermum wetzleri (fossil), and the aril of Cenolophon oxymitrum (Schumann) Holttum (recent, Thailand). The Spirematospermum aril is well developed at the base of the seed and in some specimens covers the seed entirely. The tissue of the aril is found carbonized or pyritized or as an impression on the palisade sclerenchyma of the testa. The discovery of an aril proves that Spirematospermum wetzleri belongs to the Zingiberaceae and shows its close relationship to Cenolophon oxymitrum. The finding of the Spirematospermum aril on a number of examples reaching into the Paleogene demonstrates the antiquity of this character. Hence, the reduction of the aril in some members of the living Zingiberales can be interpreted as a progression. Arillate Samen von Spirematospermum wetzleri (Heer) Chandler werden aus der miozänen Fundstelle Fasterholt in Dänemark und fünf anderen Tertiär-Fundstel-len beschrieben. Untersuchungen mit dem Raster-Elektronen-Mikroskop zeigen eine gute Übereinstimmung zwischen dem Samenmantel von Spirematospermum (fossil) und Cenolophon oxymitrum (Schumann) Holttum (rezent aus Thailand). Der Arillus ist am Hilum besonders stark entwickelt und hüllt bei einigen Ex-emplaren den gesamten Samen ein. Arillusgewebe wird in inkohltem Zustand, in pyritisierter Form und als Eindruck in der Testa nachgewiesen. Der Nachweis eines Arillus bekräftigt erneut die Zugehörigheit von Spirematospermum zu den Zingiberaceae und die nahe Verwandtschaft zu Cenolophon oxymitrum. Die Entdeckung des Arillus bei Spirematospermum-Samen, bereits aus Ablager-ungen aus dem Paläogen, zeigt das hohe Alter dieses Merkmals an. Die Reduk-tion des Arillus bei einigen Gruppen der rezenten Zingiberales ist daher als Progression zu deuten.     

Experimental disturbance by walkers affects behaviour and territory density of nesting Black-tailed Godwit Limosa limosa

In Europe, the number of areas supporting breeding Black-tailed Godwit Limosa limosa has halved over the last 30 years. Although the decline has been primarily attributed to habitat deterioration, human disturbance has also been implicated. We undertook a controlled experimental study at the Danish Special Protection Area (SPA) reserve at Tipperne, comparing bird behaviour and breeding densities from two baseline years with those in 3 years with two experimental levels of disturbance. Black-tailed Godwits flushed and showed mobbing behaviour significantly more often when disturbed. The duration of simultaneous flights by breeding pairs was greater when disturbed, leaving nests susceptible to predation. Behavioural observations suggested birds were highly sensitive to human disturbance and unlikely to habituate. Disturbance levels of seven walkers/day affected territory densities up to 500 m from routes taken by walkers, causing effective habitat loss to breeding Black-tailed Godwits. The species' sensitivity to disturbance may help explain why it has disappeared from many areas. Effective conservation of important breeding areas and maintenance of high densities of Black-tailed Godwit and other meadow birds necessitates control of public disturbance to breeding areas.