Jens Böcher

A multi-disciplinary macrofossil study of Middle Weichselian sediments at Kobbelgård, Møn, Denmark

Abstract Multi-proxy studies of radiocarbon and luminescence dated Middle Weichselian sediments and allochthonous plant and animal macrofossils from Kobbelgaard, Mon, point to a lacustrine environment with shallow mesotrophic fresh water. The lake was surrounded by mires rich in mosses and Carex , while the vegetation on the uplands was tree-less and herb dominated but with scattered shrubs. The climate was considerably colder than at the present day with average July temperatures around 11°C, about 6°C below those for the region today—probably normal for the later part of the Middle Weichselian. The sediments contain the first remains of lemmings ( Dicrostonyx torquatus and Lemmus lemmus ) found in Denmark.

Late Quaternary Environmental and Cultural Changes in the Wollaston Forland Region, Northeast Greenland

Publisher Summary This chapter reviews proxy data from a variety of natural archives sampled in the Wollaston Forland region, central Northeast Greenland. The data are used to describe long-term environmental and climatic changes, focusing on reconstructing the Holocene conditions, particularly in the Zackenberg area. The Wollaston Forland region is completely covered by the Greenland ice sheet several times during the quaternary. During the last glacial maximum (LGM), the margin of the inland ice might have extended to the shelf break off Northeast Greenland. Deglaciation of the Wollaston Forland commenced at the outer coast in the past 11,000–12,000 years, whereas the Zackenberg area was deglaciated somewhat later, in the past 10,000 years, and it took another 3,000–4,000 years before the inner fjords of the region were deglaciated. Isostatic rebound led to the rapid emergence in the early Holocene, but in the late Holocene, low-lying coastal areas were transgressed by the sea. The chapter discusses archaeological evidence for prehistoric occupation of the region.

Reproductive Biology of Four Species of Pedicularis (Scrophulariaceae) in West Greenland

Flowering pattern, mating system, and seed set were investigated for four species of Pedicularis: P. lanata (syn. P. kanei), P. hirsuta, P. flammea, and P. lapponica in West Greenland. Pedicularis lanata depends on insects for seed set. P. hirsuta and P. flammea are able to set seed by autodeposition, but P. flammea less successfully than P. hirsuta. Pedicularis lapponica mainly propagates vegetatively. Insects are rarely seen visiting the four species in the investigated area. In P. lanata the number of germinated pollen grains per stigma is much lower on average than the number of ovules per ovary, and the seed set is consequently well below its potential. Accordingly, we believe that pollen availability limits seed. Multispiked individuals of P. lanata have a lower seed set and a higher mortality rate than single-spiked plants. Pedicularis hirsuta allocates most resources to reproduction and has the highest P/O-ratio and relative reproductive success (RRS) in the area, thus being the most successful species of the four regarding seed production. Pedicularis lanata has the lowest relative reproductive success of the three sexually reproducing species due to low seed set. The four species possess flowers adapted for insect pollination, but are using different and alternative means to maintain populations: vegetative propagation, autogamy, visits by unspecialized insects, and by being perennial.

Temperature and humidity responses of the arctic-alpine seed bug Nysius groenlandicus

Field observations in Greenland as well as arena choice experiments showed that the arctic‐alpine seed bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae) is markedly xerophilous and thermophilous, preferring temperatures around 30 °C. Some variation in thermo‐preference was found among individuals from different localities in Greenland. Individuals from an inland locality (Søndre Strømfjord/Kangerlussuaq) had the highest temperature preference. Exposing individuals to rising temperature showed very high thresholds for excessive activity (ca. 41 °C), heat stupor (ca. 51 °C) and death (ca. 52 °C). All stages initially preferred the lowest humidity obtainable but gradually changed to higher humidities. The youngest nymph stages were most tolerant to desiccation. The observed preferences are interpreted as adaptations to a habitat where a warm and dry microclimate allows this obligatorily univoltine species to complete its life cycle within one year. The paper presents some general statistical approaches to analyses of behavioural responses to environmental gradients.

Coexistence of bisexual and unisexual populations of Nysius groenlandicus in the Zackenberg Valley, Northeast Greenland

The seed‐feeding true bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae) has temperature and humidity preferences similar to many desert‐inhabiting insects. Nevertheless, it is widely distributed in Greenland and occurs even in high arctic areas. This seeming paradox implies that the species has developed physiological, ecological, and behavioral mechanisms that enable it to cope with the extreme arctic environment. One of these adaptations is its ability to reproduce both sexually and asexually. Sexual reproduction is most common in coastal populations, whereas asexual reproduction (parthenogenesis) occurs mainly in inland populations. Preliminary data from the Zackenberg Valley in Northeast Greenland indicated that both reproductive strategies occurred within the same area. We therefore decided to focus on this area to find evidence of (1) coexistence of unisexual and bisexual populations, (2) factors that correlate with the distribution of the two reproductive types, and (3) morphological differences between females from sexual and asexual populations. We sampled N. groenlandicus at 51 sites within the Zackenberg area. Males and females were found in almost equal numbers in only four of the samples, and only in samples taken close to the coast line, whereas samples from the inner part of the valley consisted almost entirely of females. Thus, the distribution of uni‐ and bisexual populations at the local scale agreed with the pattern previously found for Greenland as a whole. Using data obtained from two climate stations operated in the area, we showed that average summer temperatures tend to be more favorable for N. groenlandicus in the inner part of the valley than at the coast. The inland populations inhabited small isolated patches, whereas the sexual populations were found in the more homogeneous areas along the coast. Data support the hypothesis that coexistence of the two reproductive types is maintained by a combination of environmental variability, which gives sexual reproduction an advantage, and metapopulation dynamics characterized by frequent extinctions and re‐colonizations, which favors asexual reproduction. Head width of females from unisexual populations was on average 7% larger than that of females from bisexual populations. The mechanism behind this morphological difference needs further investigation.

Holocene insect remains from south-western Greenland

Remains of plants and invertebrates from Holocene deposits in south-western Greenland include a number of insect fragments from Heteroptera and Coleoptera. Some of the finds extend the known temporal range of the species considerably back in time, and one of the taxa has not previously been found in Greenland either fossil or extant. The fossil fauna includes the weevil Rutidosoma globulus which is at present extremely rare in Greenland. Its rarity might indicate that it is a recent immigrant, but the fossil finds provide a minimum date for its arrival at around 5840 cal. years B.P. Other remains of terrestrial insects complement the scarce fossil Greenland record of the species concerned.

Are environmental factors responsible for geographic variation in the sex ratio of the Greenlandic seed‐bug Nysius groenlandicus?

Until recently nothing indicated an unequal sex ratio in the widespread Greenland seed‐bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae). However, recently populations more or less devoid of males were discovered in high arctic Northeast Greenland. This initiated an inspection of the entire material of the species collected in Greenland and now preserved at the Zoological Museum, University of Copenhagen. It was found that the sex ratio varied significantly among different locations. In most cases females were most abundant, but males were either scarce or absent only in samples from Northeast Greenland, indicating that here the species reproduces asexually. This paper demonstrates that the differing sex distributions can be explained by climatic factors (temperature, precipitation) and that the degree of continentality (distance from the open sea) promotes female‐biased sex ratios.