Poleward shifts in geographical ranges of butterfly species associated with regional warming

Abstract

letters to nature NATURE | VOL 399 | 10 JUNE 1999 | www.nature.com 579 between 270 and 4,000 ms after target onset) and to ignore changes in the distractor. Failure to respond within a reaction-time window, responding to a change in the distractor or deviating the gaze (monitored with a scleral search coil) by more than 1Њ from the fixation point caused the trial to be aborted without reward. The change in the target and distractors was selected so as to be challenging for the animal. In experiments 1 and 2 the animal correctly completed, on average, 79% of the trials, broke fixation in 11%, might have responded to the distractor stimulus in 6% and responded too early or not at all in 5% of the trials. In Experiment 3 the corresponding values are 78, 13%, 8% and 2%. In none of the three experiments was there a difference between the performances for the two possible targets. Differences between average eye positions during trials where one or the other stimulus was the target were very small, with only an average shift of 0.02Њ in the direction of the shift of position between the stimuli. Only correctly completed trials were considered. Firing rates were determined by computing the average neuronal response across trials for 1,000 ms starting 200 ms after the beginning of the target stimulus movement. Tuning curves. Tuning curves were derived by fitting the responses to the 12 directions presented with gaussian functions: r null þ dirGain ϫ exp ð Ϫ 0:5‫ء‬ðdir Ϫ prefdirÞ 2 =width 2 Þ . The four parameters of a gaussian curve capture the four features of a direction-selective cell: preferred direction ( prefdir), response to the anti-preferred direction (r null ), the directional gain (dirGain; the maximal response modulation) and the selectivity or tuning width (width; the range of directions the neuron responds to).

Do Elevated Temperature and CO2 Generally Have Counteracting Effects on Phenolic Phytochemistry of Boreal Trees?

“…Some insect species feeding on these plants have increased consumption and reduced growth (e.g., Bezemer and Jones, 1998;Veteli et al, 2002;Zvereva and Kozlov, 2006), and, therefore, may be subjected to natural enemies for a longer time under elevated CO 2 . Higher temperatures, on the other hand, may directly compensate for some of the negative effects of increased CO 2 ; increasing temperatures affect the distribution of some species by shifting ranges poleward and altitudinally upward (e.g., Parmesan et al, 1999;Battisti et al, 2005). The reason for these observed species range shifts can be a result of reducing extreme winter temperatures, increasing thermal sum, or subsequent changes in properties of the host plants.…”

Simulated distribution of vegetation types in response to climate change on the Tibetan Plateau

“…Cramer & Leemans 1991;Harras & Prentice 2003), and observations and experiments (e.g. Hattenschwiler et al 1996;Parmesan 1996;Molau & Alatalo 1998;Parmesan et al 1999) have confirmed climate-induced changes in ecosystems.…”

An overview of wetlands of Saudi Arabia: Values, threats, and perspectives

“…It should be born in mind that although a wide range of taxa have been shown to respond to climate change (Crick et al 1997;Parmesan et al 1999;Thomas and Lennon 1999;Pounds 2001;Fitter and Fitter 2002), most short-term local changes are provoked by land-use modifications or by stochasticity in the abundance and distribution of species; thus, the assignment of causality is mainly inferential. Importantly, the negative effects of climate change will thus merely be 'additive' to ongoing and increasing human-induced pressures.…”