Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. The process of evolution has given rise to biodiversity at every level of biological organisation.
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA. The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences, and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplasts with a chloroplast genome.
Lovebird is the common name for the genus Agapornis, a small group of parrots in the Old World parrot family Psittaculidae. Of the nine species in the genus, all are native to the African continent, with the grey-headed lovebird being native to the African island of Madagascar.
Silene is a genus of flowering plants in the family Caryophyllaceae. Containing nearly 900 species, it is the largest genus in the family. Common names include campion and catchfly. Many Silene species are widely distributed, particularly in the northern hemisphere.
The budgerigar, also known as the common parakeet, shell parakeet or budgie, is a small, long-tailed, seed-eating parrot. Budgies are the only species in the genus Melopsittacus. Naturally, the species is green and yellow with black, scalloped markings on the nape, back, and wings. Budgies are bred in captivity with colouring of blues, whites, yellows, greys, and even with small crests. Juveniles and chicks are monomorphic, while adults are told apart by their cere colouring, and their behaviour.
The cockatiel, also known as the weero/weiro or quarrion, is a medium-sized parrot that is a member of its own branch of the cockatoo family endemic to Australia. They are prized as household pets and companion parrots throughout the world and are relatively easy to breed compared to other parrots. As a caged bird, cockatiels are second in popularity only to the budgerigar.
Newton's parakeet, also known as the Rodrigues parakeet or Rodrigues ring-necked parakeet, is an extinct species of parrot that was endemic to the Mascarene island of Rodrigues in the western Indian Ocean. Several of its features diverged from related species, indicating long-term isolation on Rodrigues and subsequent adaptation. The rose-ringed parakeet of the same genus is a close relative and probable ancestor. Newton's parakeet may itself have been ancestral to the endemic parakeets of nearby Mauritius and Réunion.
Eye color is a polygenic phenotypic trait determined by two factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris.
Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between two species and their parents was thought to be particularly difficult to achieve, and thus hybrid species were thought to be very rare. With DNA analysis becoming more accessible in the 1990s, hybrid speciation has been shown to be a somewhat common phenomenon, particularly in plants. In botanical nomenclature, a hybrid species is also called a nothospecies. Hybrid species are by their nature polyphyletic.
Evolutionary developmental biology (evo-devo) is the study of developmental programs and patterns from an evolutionary perspective. It seeks to understand the various influences shaping the form and nature of life on the planet. Evo-devo arose as a separate branch of science rather recently. An early sign of this occurred in 1999.
Plakophilin-2 is a protein that in humans is encoded by the PKP2 gene. Plakophilin 2 is expressed in skin and cardiac muscle, where it functions to link cadherins to intermediate filaments in the cytoskeleton. In cardiac muscle, plakophilin-2 is found in desmosome structures located within intercalated discs. Mutations in PKP2 have been shown to be causal in arrhythmogenic right ventricular cardiomyopathy.
Ribosome maturation protein SBDS is a protein that in humans is encoded by the SBDS gene. An alternative transcript has been described, but its biological nature has not been determined. This gene has a closely linked pseudogene that is distally located. This gene encodes a member of a highly conserved protein family that exists in all archaea and eukaryotes.
Congenital sensorineural deafness occurs commonly in domestic cats with a white coat. It is a congenital deafness caused by a degeneration of the inner ear. Deafness is far more common in white cats than in those with other coat colours.
Parrots (Psittaciformes), also known as psittacines, are birds with a strong curved beak, upright stance, and clawed feet. They are conformed by four families that contain roughly 410 species in 101 genera, found mostly in tropical and subtropical regions. The four families are the Psittaculidae, Psittacidae, Cacatuoidea (cockatoos), and Strigopidae. One-third of all parrot species are threatened by extinction, with a higher aggregate extinction risk than any other comparable bird group. Parrots have a generally pantropical distribution with several species inhabiting temperate regions as well. The greatest diversity of parrots is in South America and Australasia.
Roan is a horse coat color pattern characterized by an even mixture of colored and white hairs on the body, while the head and "points"—lower legs, mane, and tail—are mostly solid-colored. Horses with roan coats have white hairs evenly intermingled throughout any other color. The head, legs, mane, and tail have fewer scattered white hairs or none at all. The roan pattern is dominantly inherited, and is found in many horse breeds. While the specific mutation responsible for roan has not been exactly identified, a DNA test can determine zygosity for roan in several breeds. True roan is always present at birth, though it may be hard to see until after the foal coat sheds out. The coat may lighten or darken from winter to summer, but unlike the gray coat color, which also begins with intermixed white and colored hairs, roans do not become progressively lighter in color as they age. The silvering effect of mixed white and colored hairs can create coats that look bluish or pinkish.
Hans Vandekerckhove is a Belgian painter, living and working in Ghent. From 1975 to 1997 Vandekerckhove studied Art History at University Ghent, where he wrote his graduation thesis on David Hockney.
The history of genetics can be represented on a timeline of events from the earliest work in the 1850s, to the DNA era starting in the 1940s, and the genomics era beginning in the 1970s.
Penicillium rubens is a species of fungus in the genus Penicillium and was the first species known to produce the antibiotic penicillin. It was first described by Philibert Melchior Joseph Ehi Biourge in 1923. For the discovery of penicillin from this species Alexander Fleming shared the Nobel Prize in Physiology or Medicine in 1945. The original penicillin-producing type has been variously identified as Penicillium rubrum, P. notatum, and P. chrysogenum among others, but genomic comparison and phylogenetic analysis in 2011 resolved that it is P. rubens. It is the best source of penicillins and produces benzylpenicillin (G), phenoxymethylpenicillin (V) and octanoylpenicillin (K). It also produces other important bioactive compounds such as andrastin, chrysogine, fungisporin, roquefortine, and sorbicillins.
Cornelis Andries Backer (1874–1963) was a Dutch botanist and pteridologist. He was born on 18 September 1874 in Oudenbosch and died on 22 February 1963 at Heemstede, The Netherlands. He stayed thirty years in the Dutch East Indies and did research on plant taxonomy on the islands of Java and Madura.
ADNP syndrome, also known as Helsmoortel-Van der Aa syndrome (HVDAS), is a non-inherited neurodevelopmental disorder caused by mutations in the activity-dependent neuroprotector homeobox (ADNP) gene.
