“Laws of Temperature Control of the Geographic Distribution of Terrestrial Animals and Plants,” <i>National Geographic Magazine</i> (1894)

Merriam, C. Hart

doi:10.7135/upo9780857286512.044

Cited by 80 publications

(94 citation statements)

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“…These divisions and zones had been proposed by C. Hart Merriam (1894), based primarily on temperature. The map of California that accompanied Grinnell's article showed how closely the distribution of the thrasher matched that of the Upper Sonoran division, but he acknowledged that there may be some circular reasoning, in that Merriam used the thrasher as one of the animals to define the Upper Sonoran division.…”

mentioning

confidence: 99%

Gloger's Rule, Feather-Degrading Bacteria, and Color Variation Among Song Sparrows

Burtt

Ichida

2004

Condor

167

104

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confidence: 99%

Gloger's Rule, Feather-Degrading Bacteria, and Color Variation Among Song Sparrows

Burtt

Ichida

2004

Condor

167

104

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“…Furthermore, it implies that gradual worsening of conditions across a species' habitat may lead to a sudden range fragmentation, when adaptation to a wide span of conditions within a single species becomes impossible. species' range | genetic drift | range margin | genetic variation | heterogeneous environment W hy a species' range sometimes ends abruptly, even when the environment changes smoothly across space, has interested ecologists and evolutionary biologists for many decades (1)(2)(3)(4)(5)(6)(7)(8). Haldane (2) proposed that, when the environment is spatially heterogeneous, a species may be unable to adapt and expand its range because gene flow from the center swamps the populations at the range margins, preventing their adaptation.…”

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confidence: 99%

Limits to adaptation along environmental gradients

Polechová

Barton

2015

Proc. Natl. Acad. Sci. U.S.A.

191

293

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Why do species not adapt to ever-wider ranges of conditions, gradually expanding their ecological niche and geographic range? Gene flow across environments has two conflicting effects: although it increases genetic variation, which is a prerequisite for adaptation, gene flow may swamp adaptation to local conditions. In 1956, Haldane proposed that, when the environment varies across space, "swamping" by gene flow creates a positive feedback between low population size and maladaptation, leading to a sharp range margin. However, current deterministic theory shows that, when variance can evolve, there is no such limit. Using simple analytical tools and simulations, we show that genetic drift can generate a sharp margin to a species' range, by reducing genetic variance below the level needed for adaptation to spatially variable conditions. Aided by separation of ecological and evolutionary timescales, the identified effective dimensionless parameters reveal a simple threshold that predicts when adaptation at the range margin fails. Two observable parameters determine the threshold: (i) the effective environmental gradient, which can be measured by the loss of fitness due to dispersal to a different environment; and (ii) the efficacy of selection relative to genetic drift. The theory predicts sharp range margins even in the absence of abrupt changes in the environment. Furthermore, it implies that gradual worsening of conditions across a species' habitat may lead to a sudden range fragmentation, when adaptation to a wide span of conditions within a single species becomes impossible.W hy a species' range sometimes ends abruptly, even when the environment changes smoothly across space, has interested ecologists and evolutionary biologists for many decades (1-8). Haldane (2) proposed that, when the environment is spatially heterogeneous, a species may be unable to adapt and expand its range because gene flow from the center swamps the populations at the range margins, preventing their adaptation. Theory showed that, when genetic variance is fixed, adaptation indeed fails if the environment changes too steeply across space (9), and a sharp margin to the species' range forms. The population remains well adapted only in the center of the range, and gene flow swamps variants adapted to the margins, preventing range expansion. This result also elucidates range margins in the presence of competitors: then, interspecific competition in effect steepens the environmental gradient (10). However, this limit to adaptation assumes that local genetic variation is fixed. Current deterministic theory states that, when genetic variance can evolve, there is no sharp limit to a species' range (11). The genetic mixing caused by gene flow inflates the genetic variance and facilitates further divergence. Gene flow across a phenotypic gradient maintained by the environment can generate much more variance than would be maintained by mutation alone (12,13). This rise of genetic variance with environmental gradient can allow species to adapt to ...

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“…Understanding the processes underlying the extent and limits of species distributions has fascinated scientists since the beginning of ecological research (Sclater 1858, Wallace 1876, Merriam 1894, Griggs 1914 and forms the heart of the field of biogeography (Gaston 2003). For over a century, biogeography has remained a largely descriptive discipline (Dahl 1921, Terborgh and Weske 1975, Root 1988, but it has now transformed into a much more dynamic field with modern technologies allowing for the collection and analysis of distributional and environmental information in previously unforeseeable ways.…”

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confidence: 99%

Avian SDMs: current state, challenges, and opportunities

Engler

Stiels

Schidelko

et al. 2017

Journal of Avian Biology

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Quantifying species distributions using species distribution models (SDMs) has emerged as a central method in modern biogeography. These empirical models link species occurrence data with spatial environmental information. Since their emergence in the 1990s, thousands of scientific papers have used SDMs to study organisms across the entire tree of life, with birds commanding considerable attention. Here, we review the current state of avian SDMs and point to challenges and future opportunities for specific applications, ranging from conservation biology, invasive species and predicting seabird distributions, to more general topics such as modeling avian diversity, niche evolution and seasonal distributions at a biogeographic scale. While SDMs have been criticized for being phenomenological in nature, and for their inability to explicitly account for a variety of processes affecting populations, we conclude that they remain a powerful tool to learn about past, current, and future species distributions -at least when their limitations and assumptions are recognized and addressed. We close our review by providing an outlook on prospects and synergies with other disciplines in which avian SDMs can play an important role.

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“Laws of Temperature Control of the Geographic Distribution of Terrestrial Animals and Plants,” National Geographic Magazine (1894)

Cited by 80 publications

References 0 publications

Gloger's Rule, Feather-Degrading Bacteria, and Color Variation Among Song Sparrows

Gloger's Rule, Feather-Degrading Bacteria, and Color Variation Among Song Sparrows

Limits to adaptation along environmental gradients

Avian SDMs: current state, challenges, and opportunities

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