Time filter

Source Type

Östermalm, Sweden

Bloch D.,Museum of Natural History
Archives of Natural History | Year: 2012

A beak tax was levied in the Faroe Islands from 1742 until 1881. Every man between the ages of 15 and 50 was obliged each year to submit to the authorities one raven's beak or two beaks of a crow, great skua or greater black-backed gull. A fine was imposed if a man failed in this obligation. The tax was repealed in 1881, after which men were paid for the beaks, and records of the beaks exist until 1934. A total of about 800 beaks submitted annually did not appear to deplete the bird populations, however the increasing human population from around 1800 increased the pressure on the bird populations which then declined rapidly from around 1850. A brief increase in the number of beaks occurred after 1881 when men were paid for the beaks and after that time the populations declined again. The population of crows declined more dramatically than the raven population while the great skua had declined to four breeding pairs when it was protected in 1897. The number of beaks submitted is correlated to the island size, the habitat index and the number of sheep. The smack fishery from the 1880s resulted in a better economy and better survival of the ewes in the lambing season which led to less interest in shooting the four bird species that predated on lambs. The bird populations have recovered even though the Faroese are still allowed to hunt them all the year round. © The Society for the History of Natural History.

Rogl F.,Museum of Natural History | Egger H.,Geological Survey of Austria
Geology | Year: 2010

The initial appearance of the planktonic foraminiferal genus Hantkenina has been used for about fifty years to recognize the base of the Lutetian and middle Eocene. However, probably as a result of incomplete stratigraphic records, discrepant ranges of Hantkenina have been reported by various investigators at many Eocene sections. Here we report the first complete evolutionary transition from Clavigerinella to Hantkenina, from the northwestern Tethyan deep-water section at Holzhäusl (Salzburg, Austria). A newly discovered species, Hantkenina nov. sp., is the link between Clavigerinella caucasica and Hantkenina mexicana. This finding unequivocally heralds the initial entry of Hantkenina, which is correlated to the upper part of calcareous nannoplankton Subzone NP15b (Sullivania gigas Subzone), to be defined. This indicates a mismatch of ∼4.5 m.y. between the base of the Lutetian at the type locality, which has been placed within Sub-zone NP14b, and the first appearance datum of Hantkenina. Consequently, the first occurrence of Hantkenina can no longer be used as a marker for the base of the middle Eocene. © 2010 Geological Society of America.

Konter A.,Museum of Natural History
Wilson Journal of Ornithology | Year: 2011

I analyzed the occurrence of intermediates between Western (Aechmophorus occidentalis) and Clark's (A. clarkii) grebes, of mixed pairings, and of species composition in populations of Aechmophorus grebes in California and Oregon, USA. Western Grebes comprised 69% of the aggregated total of grebes identified while intermediates represented ∼3.5% (41-46 individuals) in the populations investigated. I conclude that numbers of intermediates between purebred parental individuals have increased. Higher percentages of mixed pairings were observed at Lake Almanor; an aggregated 7.9% of nesting pairs were not composed of two purebred grebes of the same species. Statistically, mating remained strongly assortative. © 2011 by the Wilson Ornithological Society.

The type specimens of the two pseudoscorpion species described by di Caporiacco (1947) from Guyana (former British Guyana) are studied in detail. Geogarypus incertus di Caporiacco, 1947 is considered a valid species and its type locality is clarified as Guyana, Upper Demerara-Berbice region, upper Demerara valley, near Kurupukari. Paratemnus guianensis di Caporiacco, 1947 is considered a junior subjective synonym of Paratemnoides nidificator (Balzan, 1888) (syn. nov.). Lectotypes are designated for Paratemnoides minor (Balzan, 1892) and Paratemnoides nidificator. Geogarypus incertus and Paratemnoides nidificator are new additions to the fauna of French Guiana.

In doing so, Richard Glor, associate professor of ecology and evolutionary biology at KU and associate curator of herpetology at KU's Biodiversity Institute, is questioning some of the very methods scientists use to define species. Further, by combining laboratory studies with fieldwork and genomic sequence data, Glor and his team hope to determine the genetic basis for species differences and why these species diverged in the first place. Glor said biologists traditionally employ the idea of "reproductive isolation," or the inability of one kind of animal to fruitfully breed with another, to determine boundaries defining individual species. "Every student in biology has learned the philosophy of what a species is—something that can't reproduce with other species," Glor said. "So when someone describes a new species, you'd think they've done a bunch of crossing experiments [to see if a species can reproduce with another], but the answer is that nobody ever does that." He said more laboratory studies should be conducted to verify assumptions about boundaries between species and less reliance should rest on how animals look to the eye. His new grant is based on the idea that conventional methods have overlooked recent and ongoing speciation events. "Traditional taxonomists say that if species exhibit differences in their appearance—this one is green, and this one is red—they likely aren't reproducing with one another," Glor said. "I saw that as an understudied area in speciation research. We always talk about reproductive isolation, but we never test it." Glor has revealed this shortcoming in part by conducting crossing experiments on a group of lizards called bark anoles found on Hispaniola, the Caribbean island shared by Haiti and the Dominican Republic. These lizards are notable for the remarkable variation of their "dewlap," or flap of skin along the throat, that can be found in different colors and patterns. "The dewlap is colorful, kind of like a fancy car or jewelry in the human population," Glor said. "It shows the female you're attractive and helps her recognize her own species, so it's critical to sexual selection. The group that I study is particularly noteworthy because a single species exhibits very different dewlap colors and patterns (i.e., some populations are yellow, while others are red). Most anole species exhibit only a single color." Previous biologists have relied on variation in dewlaps to separate bark anoles into different subspecies. "When herpetologists drove across Haiti's mountainous Tiburon Peninsula more than 50 years ago, they saw bark anoles with pale yellow dewlaps at the beginning of their journey, bark anoles with orange and then wine red dewlaps further along, and then started seeing bark anoles with pale yellow dewlaps again by the time they reached the far tip of the peninsula," Glor said. "As a result, they described these populations with different dewlap colors as distinct subspecies." But as Glor and his colleagues obtained genomic data from the lizards, they found dewlap colors weren't a trustworthy sign of the underlying genetic differences scientists expect to find in distinct species. "These populations don't seem to be genomically differentiated," he said. "Some of those taxa that traditional methods show to be different species probably aren't different species. Natural selection is driving them to have different dewlap color and appearance for reasons not related to them being different species." In other cases, Glor said traditional methods missed species that appear to be strongly differentiated genetically because they are nearly impossible to distinguish externally. Glor's work represents the most detailed and integrated analysis ever performed on squamate reptiles—a group of almost 10,000 species, including all lizards and snakes. The research will result in the establishment of a new laboratory model organism, the first squamate genome assembled through linkage mapping and the first "estimates of heritability and the genomic basis for phenotypic traits" vital to systematically studying reptiles in general. Further, the research has resulted in a public exhibit now on display at the KU Museum of Natural History. Ultimately, however, Glor said that evolution in species is an unending and fluid process that biologists might always struggle to catalogue and measure. "All of these ideas like reproductive isolation or morphological divergence are all just benchmarks that occur as new species are forming," he said. "It could be that some species exhibit all these benchmarks, and some display only one or two. The problem identifying species is that we're trying to put discrete start and stop points on a process we know is continuous."

Discover hidden collaborations