Genetic benefits are potentially the most robust explanation of the controversial issue of evolutionary maintenance of polyandry, but the unambiguous demonstration of such benefits has been hindered by the possibility of their confusion with maternal effects. Previous research has shown that polyandrous bulb mite females produce daughters with higher fecundity than monandrous females. Here, we investigate whether this effect arises because polyandrous females invest more in their offspring, or because their offspring inherit 'good genes' from their fathers. Females were mated with either one or four (different) males. However, by sterilizing three of the four males with ionizing radiation, we eliminated any chance of sexual selection (in the polyandrous treatment) so that any differences in the female mating regimes must have been owing to maternal effects. Polyandry had no significant effect on daughter fecundity, thus indicating that any previously documented effects must have been genetic. This was further supported by a significant association between fathers' offensive sperm-competitive ability and the fecundity of their daughters. The association with fathers' sperm defensive ability was not significant, and neither was the association between fathers' sperm competitiveness and sons' reproductive success. However, sons of polyandrous females had lower reproductive success than sons of monandrous females. This shows that the maternal effects of polyandry should be taken into account whenever its costs and benefits are being considered.
Between 50,000 and 20,000 years ago, Europe experienced a series of rapid climate change events known as the Dansgaard-Oeschger cycles, which may have made areas of northern Europe more attractive for occupation by early modern humans at certain times than at others. This paper investigates when humans were occupying northern Europe in relation to these climatic changes at the archaeological site of Kraków Spadzista Street (B), by applying oxygen isotope analysis of mammoth tooth enamel carbonates (δ18O and δ13C) found at the site. The new isotopic data suggest that mean annual temperatures at Kraków Spadzista were 4-9oC colder than present and, based on comparisons with previously published isotopic data for mammoth in Europe, we argue that the Kraków assemblage most likely formed during a cold Dansgaard-Oeschger event. This suggests modern humans were able to occupy and survive in this area of northern Europe during the harsh cold phases that affected Europe at this time.
ABSTRACTBetween 50,000 and 20,000 years ago, Europe experienced a series of rapid climate change events known as the Dansgaard-Oeschger cycles, which may have made areas of northern Europe more attractive for occupation by early modern humans at certain times than at others. This paper investigates when humans were occupying northern Europe in relation to these climatic changes at the archaeological site of Kraków Spadzista Street (B), by applying oxygen isotope analysis of mammoth tooth enamel carbonates (δ 18 O and δ 13 C) found at the site. The new isotopic data suggest that mean annual temperatures at Kraków Spadzista were 4-9 o C colder than present and, based on comparisons with previously published isotopic data for mammoth in Europe, we argue that the Kraków assemblage most likely formed during a cold DansgaardOeschger event. This suggests modern humans were able to occupy and survive in this area of northern Europe during the harsh cold phases that affected Europe at this time.
The well-preserved remains (74 bones) of a woolly mammoth Mammuthus primigenius were discovered in Vistulian (Weichselian) sediments in the vicinity of Zas-tru¿e near¯arów, Lower Silesia, Poland. The mammoth female,~18-50 years old, died from unknown reason on a muddy slope of a periglacial valley and was quickly buried in sediments of~24 ka age. The results of the stable oxygen isotope analyses of bone phosphates indicate that more than one individual might have been buried at this site. The calculated stable oxygen isotope composition of water drunk by the Zastru¿e mammoth/s during its/their lifetime was-10.8±0.4‰, reflecting an approximate annual mean air temperature around 6.6±0.8°C
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