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Krackow S 《Die Naturwissenschaften》2005,92(2):78-81
Wild house mouse populations have been suggested to locally adapt to varying dispersal regimes by expressing divergent aggressivity phenotypes. This conjecture implies, first, genetic polymorphism for dispersive strategies which is supported by the finding of heritable variation for male dispersal tendency in feral house mice. Secondly, aggressivity is assumed to translate into dispersal rates. This speculation is reinforced by experimental evidence showing that non-agonistic males display lower dispersal propensity than same-aged males that have established agonistic dominance. However, the actual ontogenetic behavioural pattern and its variability among populations remain unknown. Hence, in this study the timing of agonistic onset is quantified within laboratory-reared fraternal pairs, and compared between descendants from two different feral populations. Males from the two populations (G and Z) differed strongly in agonistic development, as Z fraternal pairs had a 50% risk of agonistic onset before 23.5±2.7 days of age, while this took 57.3±5.4 days in males from population G. This difference coincided with significant genetic differentiation between the males of the two populations as determined by 11 polymorphic microsatellite markers. Furthermore, in population G, males from agonistic and amicable fraternal pairs exhibited significant genetic differentiation. These results corroborate the supposition of genetic variability for dispersive strategies in house mice, and identify the ontogenetic timing of agonistic phenotype development as the potential basis for genetic differentiation. This opens a unique opportunity to study the genetic determination of a complex mammalian behavioural syndrome in a life history context, using a simple laboratory paradigm. 相似文献
24.
A previous model of the global heat balance has been expanded by including the influence of SO2 pollution, water content of the atmosphere and cloudiness. It was found that the previous results were not changed significantly by this expansion of the model. The conclusions set up uising the previous model were still valid: (1) it is great importance to include the buffer capacity of the sea, including its dependence on pH and the temperature; (2) it is of importance to include natural climatic variations; (3) the dominanting factor is the trend in the consumption of fossil fuel. 相似文献
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Sven Erik Jrgensen 《Ecological modelling》1995,80(2-3)
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András Bardossy Arne Färber Steffen Schönau Bernhard Westrich Thomas Jancke Gerhard Schmid Sven Wurms Karl Stahr Thomas Gaiser Harald Frauenknecht Thilo Streck Joachim Ingwersen Claudia Kreschnak Ulrich Kern Hilke Heppelmann Ekkehard Christoffels Ulrich Förstner Patrick Jacobs 《Environmental Sciences Europe》2006,18(1):67-69
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Seasonal trends in the gonad index (GI) of two widely separated populations of black teatfish, Holothuria whitmaei (formerly included in Holothuria nobilis), were investigated between Pacific (Great Barrier Reef) and Indian Ocean (Ningaloo Reef) coral reefs of Australia. Reproductive
activity followed a similar annual trend, with the GI of both populations peaking typically between April and June. Macroscopic
and histological analysis of Ningaloo Reef specimens revealed that large germinal tubules, positioned centrally on the gonad
basis, progressed through four maturity stages: growing (II); mature (III); partly spawned (IV); and spent (V). Growing tubules
dominated the central region of the gonad basis between January and March, followed by an increase in the number of mature
tubules throughout the GI peak (April–June). The progressive appearance of partly spawned and spent tubules between June and
October suggests that spawning in H. whitmaei continues intermittently over an extended period throughout the austral winter. The examination of the gonad structure of
sexually mature male and female specimens identified five tubule size classes in total (C1 to C5), each of differing physical and gametogenic status. In females, smaller C1 tubules located at the anterior edge of the gonad basis contained pre- to early vitellogenic oocytes. Larger C2 and C3 tubule cohorts, positioned centrally on the gonad basis, contained mid- to late-stage vitellogenic oocytes. Smaller C4 and C5 tubules, located at the posterior edge, contained only relict oocytes. Similar physical and gametogenic differences were
apparent between tubule cohorts in male specimens. We propose that these results, together with evidence of incomplete gonad
resorption over the austral summer, indicate that gonad development in H. whitmaei conforms to the predictions of the Tubule Recruitment Model (TRM). The TRM is reported rarely among tropical aspidochirotes,
and results presented here (1) provide the first direct evidence of this model in H. whitmaei, and (2) confirm that this species is one of the few winter-spawning tropical invertebrates. 相似文献
29.
Adrian Vallin Sven Jakobsson Christer Wiklund 《Behavioral ecology and sociobiology》2007,61(9):1419-1424
Large eyespots on the wings of butterflies and moths have been ascribed generally intimidating qualities by creating a frightening
image of a bird or mammal much larger than the insect bearing the eyespots. However, evidence for this anti-predator adaptation
has been largely anecdotal and only recently were peacock butterflies, Inachis io, shown to effectively thwart attacks from blue tits, Parus caeruleus. Here, we test whether large eyespots on lepidopterans are generally effective in preventing attacks from small passerines
and whether the size of insect or bird can influence the outcome of interactions. We staged experiments between the larger
eyed hawkmoths, Smerinthus ocellatus, and the smaller peacock butterflies, I. io, and the larger great tits, Parus major, and the smaller blue tits, P. caeruleus. Survival differed substantially between the insect species with 21 of 24 peacock butterflies, but only 6 of 27 eyed hawkmoths,
surviving attacks from the birds. Thus, surprisingly, the smaller prey survived to a higher extent, suggesting that factors
other than insect size may be important. However, great tits were less easily intimidated by the insects’ eyespots and deimatic
behaviour and consumed 16 of 26, but the blue tits only 8 of 25, of the butterflies and hawkmoths. Our results demonstrate
that eyespots per se do not guarantee survival and that these two insects bearing equally large eyespots are not equally well
protected against predation. 相似文献
30.
The model of spatial distribution of main forest soil groups in Croatia was developed as a function of basic pedogenetic factors: lithological substratum, macroclimate and relief. Used data about soil group, lithological substratum, terrain slope and aspect were collected on 1881 soil profiles. Macroclimatic data were estimated for each soil profile by spatial interpolation between meteorological stations. Feedforward neural networks were used as modelling tool. The final model has total classification correctness of 63.5% for training data set and 62.3% for independent test data set. The best result (86.4%) was achieved for fluvisols which are strongly spatially correlated with alluvial sediment in a flood plains. The worst result was achieved for luvisol (14.2%) which mainly comprised very old soils, probably developed under pedogenetic factors different from actual. The model was applied on entire Croatian territory aiming at construction of potential spatial distribution of main forest soils (without human impact), which was compared by the potential spatial distribution of major forest types modelled independently. 相似文献