Sex reversals whereby individuals of one genetic sex develop the phenotype of the opposite sex occur in ectothermic vertebrates with genetic sex-determination systems that are sensitive to extreme temperatures during sexual differentiation. Recent rises in global temperatures have led researchers to predict that sex reversals will become more common, resulting in the distortion of many populations' sex ratios. However, it is unclear whether susceptibility to climate-driven sex-ratio shifts depends on the type of sex determination that varies across species. First, we show here using individual-based theoretical models that XX/XY (male-heterogametic) and ZZ/ZW (female-heterogametic) sex-determination systems can respond differentially to temperature-induced sex reversals. Interestingly, the impacts of climate warming on adult sex ratio (ASR) depend on the effects of both genotypic and phenotypic sex on survival and reproduction. Second, we analyse the temporal changes of ASR in natural amphibian populations using data from the literature, and find that ASR shifted towards males in ZZ/ZW species over the past 60 years, but did not change significantly in XX/XY species. Our results highlight the fact that we need a better understanding of the interactions between genetic and environmental sex-determining mechanisms to predict the responses of ectotherms to climate change and the associated extinction risks.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.
Combined sedimentological and structural analysis was carried out in the field and on 2D seismic reflection profiles to recognize pre-orogenic structures in a Cretaceous fold-and-thrust belt. Detailed field observations were made in the Keszthely Hills, Western Hungary, while 2D seismic interpretation was carried out in the neighbouring Zala Basin. As a result, a fault-controlled intraplatform basin system was identified by a detailed analysis of bounding faults, and related outcropscale structures. The Norian-Rhaetian (227-201.3 Ma) synsedimentary faulting was associated with talus breccia formation, small-scale faulting, and dyke formation, in addition to slumping and other soft-sediment deformations. Based on the distribution of talus breccia, WNW-ESE-trending map-scale normal faults were identified in the Keszthely Hills, which is in agreement with the directly observed outcrop-scale synsedimentary faults. On seismic sections, similar WNW-or NWtrending Late Triassic normal faults were identified based on thickness variations of the syn-rift sediments and the presence of wedge-shaped bodies of talus breccia. Normal faulting occurred already in the Norian, and extensional tectonics was active through the Early and Middle Jurassic. The Late Triassic grabens of the western Transdanubian Range could be correlated with those in western part of the Southern Alps, and the Bajuvaric nappe system of the Northern Calcareous Alps. These grabens were situated on the proximal Adriatic margin, and they represent the first sign of the Alpine Tethys rifting. The locus of extension was laterally migrated westward, towards the distal Adriatic margin during Early and Middle Jurassic.
The movement of butterflies within habitat patches is usually assumed to be random, although few studies have shown this unambiguously. In the case of the highly specialized genus Maculinea, two contradictory hypotheses exist to explain the movement and distribution of imagos within patches: (1) due to the high spatial variance of survival rates among caterpillars, the "risk-spreading" hypothesis predicts that females will tend to make linear flight paths in order to maximize their net displacement and scatter the eggs as widely as possible; and (2) recent mark-release-recapture (MRR) data suggest that within-habitat displacement of some Maculinea species is constrained and that adults may establish home ranges. We tested both hypothesis by analysing the movement pattern of individuals. We also investigated whether egg laying is time constrained, which would enhance the trade-off between flying and egg laying. Thirty females of Maculinea rebeli (Lepidoptera: Lycaenidae) were tracked within a single population in Central Hungary. Their egg-laying behaviour and individual patterns of movement were recorded, and the latter were compared with random walk model predictions. The population was also sampled by MRR to estimate survival rates, and four non-mated, freshly eclosed females were dissected to assess their potential egg load. Net squared displacement of females was significantly lower than predicted by the random walk model and declined continuously after the 15th move. The ratio of net displacement and cumulative move length decreased with the number of moves, supporting the hypothesis that Maculinea butterflies establish home ranges. We found that low survival and a low rate of egg laying prevented females from laying their potential number of eggs within their lifespan. Time limitation increased the cost of movement, providing another possible explanation for the restricted movement of females.
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