MADS-domain transcription factors are involved in signal transduction and developmental control in plants, animals and fungi. Because their diversification is linked to the origin of novelties in ...multicellular eukaryotes, the early evolution of MADS-domain proteins is of interest, but has remained enigmatic. Employing whole genome sequence information and remote homology detection methods, we demonstrate that the MADS domain originated from a region of topoisomerases IIA subunit A. Furthermore, we provide evidence that gene duplication occurred in the lineage that led to the MRCA of extant eukaryotes, giving rise to SRF-like and MEF2-like MADS-box genes.
Seabirds in seasonal environments are often long-distance migrants and, for many species and populations, their ranges throughout the non-breeding period are unknown. As conditions during the ...non-breeding season often affect subsequent performance, the choice of migration strategy can have major implications for timing of breeding and success and, ultimately, population dynamics. We tracked south polar skuasCatharacta maccormickifrom a single breeding population at King George Island in the South Shetland Islands (Antarctica). Overall, 27 birds (69%) migrated to the northern Atlantic (3 regions), 10 birds (26%) to the northern Pacific Ocean (2 regions), and 2 birds wintered in the southern hemisphere. Individuals tracked in consecutive non-breeding seasons chose the same ocean for wintering. Despite migrating to different oceans, birds showed a similar figure-of-eight flight pattern and equivalent residency periods in the main wintering areas. In addition, 87% of the migrants used terminal stop-over sites off South America shortly before returning to the breeding site. High diversity of migration patterns may buffer south polar skuas from climate change and other anthropogenic threats.
Based on extensive mitochondrial DNA (mtDNA) sequence data, we previously showed that the model of speciation among species of herring gull (Larus argentatus) complex was not that of a ring species, ...but most likely due more complex speciation scenario's. We also found that two species, herring gull and glaucous gull (L. hyperboreus) displayed an unexpected biphyletic distribution of their mtDNA haplotypes. It was evident that mtDNA sequence data alone were far from sufficient to obtain a more accurate and detailed insight into the demographic processes that underlie speciation of this complex, and that extensive autosomal genetic analysis was warranted.
For this reason, the present study focuses on the reconstruction of the phylogeographic history of a limited number of gull species by means of a combined approach of mtDNA sequence data and 230 autosomal amplified fragment length polymorphism (AFLP) loci. At the species level, the mtDNA and AFLP genetic data were largely congruent. Not only for argentatus and hyperboreus, but also among a third species, great black-backed gull (L. marinus) we observed two distinct groups of mtDNA sequence haplotypes. Based on the AFLP data we were also able to detect distinct genetic subgroups among the various argentatus, hyperboreus, and marinus populations, supporting our initial hypothesis that complex demographic scenario's underlie speciation in the herring gull complex.
We present evidence that for each of these three biphyletic gull species, extensive mtDNA introgression could have taken place among the various geographically distinct subpopulations, or even among current species. Moreover, based on a large number of autosomal AFLP loci, we found evidence for distinct and complex demographic scenario's for each of the three species we studied. A more refined insight into the exact phylogeographic history within the herring gull complex is still impossible, and requires detailed autosomal sequence information, a topic of our future studies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven ...by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio.
Recent studies on mate-quality recognition in passerines showed that females use subtle differences in sound production to assess males. We analysed long calls of brown skuas,
Catharacta antarctica ...lonnbergi, to test whether vocal performance could serve as an indicator of individual quality in a nonpasserine species. Measurements of vocal performances focused on two acoustic parameters for which motor constraints have been reported in passerines, namely ‘vocal deviation’ and ‘peak performance’. As potential indicators of individual quality we measured body size, body condition (body mass corrected for size) and mean reproductive success. We found a triangular distribution of calls between note repetition rate and frequency bandwidth. Males performing long calls closer to the performance limit had a higher mean reproductive success than males that show long calls with a larger vocal deviation. Similarly, males calling with a high peak performance were more successful breeders than males with low peak performance. Our findings indicate that long calls of brown skuas are limited by motor constraints similar to vocalizations in passerines. We show that differences in vocal performance reflect male's reproductive success with more successful breeders producing the more difficult calls. This implies that limits on vocal performance due to motor constraints present a suitable mechanism for mate-quality recognition in nonpasserine birds.
Whilst we have now a good understanding how past glaciation influenced species at the northern hemisphere, our knowledge of patterns and modes of speciation is far more limited for the southern ...hemisphere. We provide mtDNA based data on the phylogeography of a circumpolar distributed southern hemisphere seabird group—the southern skua complex (
Catharacta spp.). Diversification of southern skuas dates between 210,000
yBP and 150,000
yBP and coincides with a glacial spanning 230,000–140,000
yBP. Skuas most likely first inhabited the Antarctic continent, in the course of global cooling and increasing glaciation spread to the sub-antarctic islands and Tristan da Cunha and finally colonized Patagonia and the Falkland Islands at the glacial maximum. Despite significant differences between taxa most populations still exchange genes with neighboring populations of other taxa and speciation is incomplete.
We used multiple regression, path analysis and non-parametric selection surface visualisation to investigate natural and sexual selection and, in addition, cross-sectional female choice statistics to ...analyse female choice in a wild population of the field cricket Gryllus campestris L. in central Germany. Adults (167 males, 75 females) were individually marked and followed daily over the entire adult stage. Two morphological traits (pronotum width, body condition) and two behavioural traits (burrow occupation time, daily displacement) were measured for each male and used in selection analyses. Individuals mated multiply and male mating success was strongly right skewed with less than 6% of the population achieving 50% of the copulations. In males, analysis of natural selection in terms of lifespan revealed positive directional selection on burrow occupation time and stabilising selection on daily displacement. Analysis of sexual selection in term of mating success showed positive directional selection on pronotum width and lifespan. Path analysis confirmed the close association between natural and sexual selection and illustrated indirect effects of the behavioural variables on mating success via their effect on lifespan. Multiple regression analysis further indicated positive quadratic (disruptive) sexual selection on lifespan but the non-parametric cubic spline regression showed this to be an artefact of the quadratic approach. In fact, lifespan was under “threshold selection” i.e. it was not under selection below a threshold and under positive directional sexual selection above the threshold. A positive correlational selection gradient between lifespan and body condition revealed that a high body condition is advantageous among long-lived males. Female choice statistics showed that females chose large and heavy males in the beginning of the season only and that choosiness decreases with increasing distance to potential alternative mates. Our findings highlight the benefits of combining several analytical methods to uncover selection patterns and to avoid misinterpretations based on single methods.
1. Cricket model systems have greatly enhanced our knowledge about mate choice and sexual selection. However, no studies exist that take seasonal dynamics into account and that follow individual ...males over the complete adult stage in the wild. In the present study, all adult field crickets (Gryllus campestris L.) were individually marked and measured in a population in central Germany and their behaviour was followed over their life from May to July 2000. 2. The population reached a maximum of 108 males within 10 days and continuously declined thereafter. Daily mortality was positively correlated with burrow-changing activity, which was highest at high mean temperatures. Median burrow occupation time was short at 1 day but males stayed up to 34 days in one burrow. Heavy males stayed longer in burrows and achieved a higher age. 3. Male displacement was on average 2.8 m per day and up to 284 m during their life. Displacement and lifespan were negatively correlated. 4. Burrows were highly aggregated at the meadow in areas of vegetation cover <85%. Aggregation of males increased with advancing season and declining population size. Consequently, nearest-neighbour distances remained stable at 5 m until the 50th day of the study. 5. About half of the 159 detected matings occurred 4-6 h after sunrise. An increased mating frequency was observed between the 30th and 50th day after adult moult.
Mass loss of chick‐rearing birds can be the direct consequence of physiological stress (reproductive stress hypothesis) or an adaptive mass adjustment in response to the increased demands on flight ...efficiency during the flight‐intensive chick‐rearing period (adaptive mass loss hypothesis). To test which of these hypotheses best explains mass loss in South Polar Skuas Stercorarius maccormicki rearing chicks, a food supplementation experiment was carried out in the austral summer 2000/01 at King George Island, Antarctica. Half of the breeding pairs were fed about 20% of the chick's daily energy demand every second day and chick growth and adult nest attendance were recorded. Parents were caught at the start and the end of chick‐rearing to calculate adult mass loss. Male parents of food‐supplemented pairs attended their nest territories more than control males but females kept their attendance constant. Chick growth was only minimally affected and the treatment probably had no fitness consequences. Male Skuas in control pairs had a higher deviation from the body size–mass regression at the end of chick‐rearing compared with the start, supporting the stress hypothesis, whereas female deviation remained unchanged. Males of food‐supplemented pairs were heavier than unsupplemented males at the end of the breeding cycle but not significantly so. Food‐supplemented females were lighter at the end, supporting the adaptive mass loss hypothesis. Adult mass loss is thus best explained by the reproductive stress hypothesis in males but by the adaptive mass loss hypothesis in females. However, the two hypotheses are not mutually exclusive and the results do not exclude the possibility that mass loss in females is stress‐induced but the amount of mass lost is an adaptive adjustment to the reliability of the food supply. The finding that members of a breeding pair may follow different strategies of mass adjustment has implications for the use of mass loss as an index of parental effort. Without knowing which strategy each sex has adopted it is of little use to compare mass loss between parents.
The use of DNA sequence data in plant systematics has brought us closer than ever to formulating well-founded hypotheses about phylogenetic relationships, and phylogenetic research keeps on revealing ...that plant genera as traditionally circumscribed often are not monophyletic. Here, we assess the monophyly of all genera of vascular plants found in Germany. Using a survey of the phylogenetic literature, we discuss which classifications would be consistent with the phylogenetic relationships found and could be followed, provided monophyly is accepted as the primary criterion for circumscribing taxa. We indicate whether and which names are available when changes in generic assignment are made (but do not present a comprehensive review of the nomenclatural aspects of such names). Among the 840 genera examined, we identified c. 140 where data quality is sufficiently high to conclude that they are not monophyletic, and an additional c. 20 where monophyly is questionable but where data quality is not yet sufficient to reach convincing conclusions. While it is still fiercely debated how a phylogenetic tree should be translated into a classification, our results could serve as a guide to the likely consequences of systematic research for the taxonomy of the German flora and the floras of neighbouring countries. Citation: Kadereit J. W., Albach D. C., Ehrendorfer F., Galbany-Casals M., Garcia-Jacas N., Gehrke B., Kadereit G., Kilian N., Klein J. T., Koch M. A., Kropf M., Oberprieler C., Pirie M. D., Ritz C. M., Röser M., Spalik K., Susanna A., Weigend M., Welk E., Wesche K., Zhang L.-B. & Dillenberger M. S. 2016: Which changes are needed to render all genera of the German flora monophyletic? — Willdenowia 46: 39–91. doi: http://dx.doi.org/10.3372/wi.46.46105 Version of record first published online on 24 March 2016 ahead of inclusion in April 2016 issue.
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