Extinction of populations occurs naturally, but global extinction rates are accelerating, making understanding extinction a high priority for conservation. Extinction in experimental populations of brine shrimp (Artemia franciscana) was measured to assess hypothesized extinction processes. Greater initial population size, greater maximum population size supported by the environment, and lower v...

When we hear the word extinction, most of us immediately think of dinosaurs and woolly mammoths and cataclysmic events precipitating their extinction. Some of us are also aware of current extinction threats and recent extinctions, but few, if any, of us understand the varying and complex circumstances under which extinction actually happens. It turns out that extinction and species survival are...

We study internal extinction of late-type galaxies in the Sloan Digital Sky Survey. We find that the degree of internal extinction depends on both the concentration index c and Ks-band absolute magnitude MK . We give simple fitting functions for internal extinction. In particular, we present analytic formulae giving the extinction-corrected magnitudes from the observed optical parameters. For e...

When we hear the word extinction, most of us immediately think of dinosaurs and woolly mammoths and cataclysmic events precipitating their extinction. Some of us are also aware of current extinction threats and recent extinctions, but few, if any, of us understand the varying and complex circumstances under which extinction actually happens. It turns out that extinction and species survival are...

Fear extinction correlates with increased infralimbic (IL) neuronal excitability. Since small conductance Ca(2+)-dependent K(+) (SK) channels modulate neuronal excitability and certain types of learning and memory, pharmacological modulation of SK channels could be used to regulate IL excitability and fear extinction. To test this, we first determined the effect of blocking SK channels with apa...

Fear extinction is defined as the attenuation of a conditioned-fear memory by re-exposing animals to the conditioned stimulus without the aversive stimulus. This process is known to be effectively enhanced via administration of D-cycloserine (DCS), a partial NMDA-receptor agonist. However, other glutamatergic mechanisms, such as interference with metabotropic glutamate receptor (mGluR) subtypes...

If we are to plan conservation strategies that minimize the loss of evolutionary history through human-caused extinctions, we must understand how this loss is related to phylogenetic patterns in current extinction risks and past speciation rates. Nee & May (1997, Science 278, 692-694) showed that for a randomly evolving clade (i) a single round of random extinction removed relatively little evo...

The end Permian extinction was the greatest mass extinction of the Phanerozoic Era. It impacted marine and terrestrial plants and animals. Although the rate of the extinction has been controversial in the past, recent evidence suggests that the extinction progressed in two pulses approximately 5-12 million years apart. The second pulse of the extinction is marked by a sharp temperature spike an...