Morfometría en dos poblaciones californianas de Gumaga nigricula(McLachlan 1871) (Trichoptera: Sericostomatidae)

Eighty Gumaga nigricula larvae from Hopland Spring and Big Sulphur Creek, northern California, USA, were studied to quantify possible dissimilarities among them. The populations are statistically different in two meristic characters: number of setae on the anterior margin of the pronotum and number of pleural sclerites on abdominal segment VIII. They also appear to be different in a continuous character, head width/length ratio. In all cases, specimens from Big Sulphur Creek have statistically significant higher values. These data are congruent with the hypothesis that there is biologically significant genetic isolation between these populations.Ochenta larvas de Gumaga nigricula provenientes del Hopland Spring y del Big Sulphur Creek en el norte de California, Estados Unidos, se estudiaron para cuantificar las posibles diferencias entre ellas. Estas poblaciones son estadísticamente diferentes en dos características merísticas: el número de cerdas en el margen anterior del pronoto y el número de escleritos pleurales en el segmento abdominal VIH. Estas poblaciones también parecen ser diferentes en la característica continua, cociente ancho/largo de la cabeza. En todos los casos, los ejemplares del Big Sulphur Creek tienen valores significativamente mayores. Estos datos son congruentes con la hipótesis de que existe aislamiento reproductivo significativo entre estas dos poblaciones

Chip Off the Old Block : Generation, Development, and Ancestral Concepts of Heredity

Heredity is such a fundamental concept that it is hard to imagine a world where the connection between parents and offspring is not understood. Three hundred years ago thinking of the phenomenon of heredity bore on a cluster of distinct philosophical questions inherited from antiquity concerning the nature and origin of substances or beings that lacked biological meaning. We are reminded of this philosophical heritage by the fact that in the 18th century the study of reproduction, embryology and development was referred to as "the science of generation". It is now clear that reproduction, the biological process by which parents produce offspring, is a fundamental feature of all life on Earth. Heredity, the transmission of traits from parents to offspring via sexual or asexual reproduction, allows differences between individuals to accumulate and evolve through natural selection. Genetics is the study of heredity, and in particular, variation of fundamental units responsible for heredity. Ideas underlying this theory evolved in considerably different and unrelated ways across a number of knowledge domains, including philosophy, medicine, natural history, and breeding. The fusion of these different domains into a single comprehensive theory in 19th century biology was a historically and culturally interdependent process, thus examining genetic prehistory should unravel these entanglements. The major goal of our review is tracing the various threads of thought that gradually converged into our contemporary understanding of heredity.Peer reviewe

Themes of Biological Inheritance in Early Nineteenth Century Sheep Breeding as Revealed by J. M. Ehrenfels

Among the so-called sheep breeders interested in biological inheritance in the late eighteenth and early nineteenth centuries and well before Gregor Johann Mendel, J. M. Ehrenfels (1767–1843) produced some of the most cogent writings on the subject. Although earlier in his career Ehrenfels was a strong advocate of environmental factors as influencers on the appearance of organisms, as a result of his discussions with Imre Festetics, he became convinced that whatever is passed from parents to progeny is more important and it is dependent on a “genetic force, the mother of all living things”. The sheep breeders kept issues of inheritance at the forefront of the Central European cultural context late into the nineteenth century

Themes of Biological Inheritance in Early Nineteenth Century Sheep Breeding as Revealed by J. M. Ehrenfels

Among the so-called sheep breeders interested in biological inheritance in the late eighteenth and early nineteenth centuries and well before Gregor Johann Mendel, J. M. Ehrenfels (1767–1843) produced some of the most cogent writings on the subject. Although earlier in his career Ehrenfels was a strong advocate of environmental factors as influencers on the appearance of organisms, as a result of his discussions with Imre Festetics, he became convinced that whatever is passed from parents to progeny is more important and it is dependent on a “genetic force, the mother of all living things”. The sheep breeders kept issues of inheritance at the forefront of the Central European cultural context late into the nineteenth century

EPITRAGUS AURULENTUS (KIRSCH) (COLEOPTERA: TENEBRIONIDAE): A NEW RECORD AND REPORT FOR PUERTO RICO

EPITRAGUS AURULENTUS (KIRSCH) (COLEOPTERA: TENEBRIONIDAE): A NEW RECORD AND REPORT FOR PUERTO RIC

Mimush Sheep and the Spectre of Inbreeding : Historical Background for Festetics's Organic and Genetic Laws Four Decades Before Mendel's Experiments in Peas

The upheavals of late eighteenth century Europe encouraged people to demand greater liberties, including the freedom to explore the natural world, individually or as part of investigative associations. The Moravian Agricultural and Natural Science Society, organized by Christian Carl Andre, was one such group of keen practitioners of theoretical and applied scientific disciplines. Headquartered in the "Moravian Manchester" Brunn (nowadays Brno), the centre of the textile industry, society members debated the improvement of sheep wool to fulfil the needs of the Habsburg armies fighting in the Napoleonic Wars. Wool, as the raw material of soldiers' clothing, could influence the war's outcome. During the early nineteenth century, wool united politics, economics, and science in Brno, where breeders and natural scientists investigated the possibilities of increasing wool production. They regularly discussed how "climate" or "seed" characteristics influenced wool quality and quantity. Breeders and academics put their knowledge into immediate practice to create sheep with better wool traits through consanguineous matching of animals and artificial selection. This apparent disregard for the incest taboo, however, was viewed as violating natural laws and cultural norms. The debate intensified between 1817 and 1820, when a Hungarian veteran soldier, sheep breeder, and self-taught natural scientist, Imre (Emmerich) Festetics, displayed his inbred Mimush sheep, which yielded wool extremely well suited for the fabrication of light but strong garments. Members of the Society questioned whether such "bastard sheep" would be prone to climatic degeneration, should be regarded as freaks of nature, or could be explained by natural laws. The exploration of inbreeding in sheep began to be distilled into hereditary principles that culminated in 1819 with Festetics's "laws of organic functions" and "genetic laws of nature," four decades before Gregor Johann Mendel's seminal work on heredity in peas.Peer reviewe

Life habits, hox genes, and affinities of a 311 million-year-old holometabolan larva

Background: Holometabolous insects are the most diverse, speciose and ubiquitous group of multicellular organisms in terrestrial and freshwater ecosystems. The enormous evolutionary and ecological success of Holometabola has been attributed to their unique postembryonic life phases in which nonreproductive and wingless larvae differ significantly in morphology and life habits from their reproductive and mostly winged adults, separated by a resting stage, the pupa. Little is known of the evolutionary developmental mechanisms that produced the holometabolous larval condition and their Paleozoic origin based on fossils and phylogeny. Results: We provide a detailed anatomic description of a 311 million-year-old specimen, the oldest known holometabolous larva, from the Mazon Creek deposits of Illinois, U.S.A. The head is ovoidal, downwardly oriented, broadly attached to the anterior thorax, and bears possible simple eyes and antennae with insertions encircled by molting sutures;other sutures are present but often indistinct. Mouthparts are generalized, consisting of five recognizable segments: a clypeo-labral complex, mandibles, possible hypopharynx, a maxilla bearing indistinct palp-like appendages, and labium. Distinctive mandibles are robust, triangular, and dicondylic. The thorax is delineated into three, nonoverlapping regions of distinctive surface texture, each with legs of seven elements, the terminal-most bearing paired claws. The abdomen has ten segments deployed in register with overlapping tergites;the penultimate segment bears a paired, cercus-like structure. The anterior eight segments bear clawless leglets more diminutive than the thoracic legs in length and cross-sectional diameter, and inserted more ventrolaterally than ventrally on the abdominal sidewall. Conclusions: Srokalarva berthei occurred in an evolutionary developmental context likely responsible for the early macroevolutionary success of holometabolous insects. Srokalarva berthei bore head and prothoracic structures, leglet series on successive abdominal segments - in addition to comparable features on a second taxon eight million-years-younger - that indicates Hox-gene regulation of segmental and appendage patterning among earliest Holometabola. Srokalarva berthei body features suggest a caterpillar-like body plan and head structures indicating herbivory consistent with known, contemporaneous insect feeding damage on seed plants. Taxonomic resolution places Srokalarva berthei as an extinct lineage, apparently possessing features closer to neuropteroid than other holometabolous lineages