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HIGHLY SOCIAL BIRDS. “Reduction of colony size below some critical threshold may impair breeding behaviour to the extent that success declines, perhaps ultimately resulting in the disappearance of the colony...and increased dispersion of the colonies.” https://www.britishbirds.co.uk/wp-content/uploads/article_files/V96/V96_N09/V96_N09_P439_446_A004.pdf View in LinkedIn

COUNTRY FACTORS. “Factors proposed for the urban House Sparrow decline: predation by hawks and cats; increased bird competition for food; nesting site losses; pollution; lack of insect food; increased pesticide use; smaller colony sizes.” https://www.britishbirds.co.uk/wp-content/uploads/article_files/V96/V96_N09/V96_N09_P439_446_A004.pdf View in LinkedIn

TWO GROUPS. “There is no evidence of any significant interchange of House Sparrows between farmland and urban populations, and it is almost certain that the factors for the declines are largely unrelated.” https://www.britishbirds.co.uk/wp-content/uploads/article_files/V96/V96_N09/V96_N09_P439_446_A004.pdf View in LinkedIn

URBAN IMPACT. “In contrast, a gradual decline in urban centres continued, with little change for 50 years from the 1930s, before the urban population went into free-fall in the late 1980s or early 1990s. A gradual and continuing decline is probably also taking place in suburbs and small towns, though it has not yet become catastrophic.” https://www.britishbirds.co.uk/wp-content/uploads/article_files/V96/V96_N09/V96_N09_P439_446_A004.pdf View in LinkedIn

TWO DYNAMICS. “The situation in farmland appears to be quite distinct from that in urban centres. A major decline in farmland began in the late 1970s, but after a decrease of about 60% the population had stabilised by about 1995.” https://www.britishbirds.co.uk/wp-content/uploads/article_files/V96/V96_N09/V96_N09_P439_446_A004.pdf View in LinkedIn

MITOTIC CLOCK. “Hayflick first described the limited replicative capacity of normal human fibroblasts more than 30 years ago. Since then, numerous other somatic cell types, including epithelial cells, endothelial cells, myoblasts, astrocytes, and lymphocytes, have also shown evidence of a mitotic clock which limits their division capacity.” https://lnkd.in/dFjeJA3 View in LinkedIn

RANGE OF LONGEVITY. “Different species vary dramatically in how long they life. The dome-shelled Galápagos giant tortoise (Geochelone elephantopus) can reach an age of about 180 years, whereas some mayfly species (belonging to the insect order Ephemeroptera) die after about 30 minutes. Even older than giant tortoises are certain trees, such as the yew (Taxus baccata), with some specimens between 4,000 and 5,000 years old. A few other organisms, such as freshwater polyps of the genus Hydra, are thought to age at a negligible rate or to be even potentially immortal, although this is still somewhat controversial.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

TELOMERASE. “A current hypothesis gaining prominence proposes that activation of the enzyme telomerase is necessary for cells to become immortal, or capable of proliferating indefinitely. The theory suggests that almost all cancer cells must attain immortality for progression to malignant states and, hence, require activation of telomerase.” http://jnci.oxfordjournals.org/content/87/12/884.short View in LinkedIn

TWO AGING MODELS. “The classical evolutionary theory of aging has therefore two fundamental cornerstones: MA and AP. However, it is worth noting that both models are conceptually very similar: under MA, aging evolves through the accumulation of effectively neutral mutations with deleterious late-life effects, whereas, under AP, aging occurs due to mutations with beneficial early- and deleterious late-life effects. In reality, probably both types of mutations occur in populations, yet their relative frequencies remain unknown.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

CYCLE ARREST. “Cellular senescence is an irreversible cell cycle arrest caused by intrinsic or extrinsic stress, such as shortened telomeres, DNA damage, induced oncogenes, or chromatin perturbation.” https://lnkd.in/dKvxxVz View in LinkedIn