The Role of Leaf Movements for Optimizing Photosynthesis in Relation to Environmental Variation

Role of pulvinar chloroplasts in light-driven leaf movements of the trifoliate leaf of bean (Phaseolus vulgarisL.)

Journal of Experimental Botany ◽

10.1093/jxb/46.9.1215 ◽

1995 ◽

Vol 46 (9) ◽

pp. 1215-1222 ◽

Cited By ~ 6

Author(s):

Dov Koller ◽

Olle Björkman ◽

Sigalit Ritter

Keyword(s):

Trifoliate Leaf ◽

Leaf Movements

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A COMMENT ON THE ROLE OF ENVIRONMENTAL VARIATION IN MAINTAINING POLYMORPHISMS IN NATURAL POPULATIONS

Evolution ◽

10.1111/j.1558-5646.1976.tb00897.x ◽

1976 ◽

Vol 30 (1) ◽

pp. 188-190 ◽

Cited By ~ 10

Author(s):

Edwin H. Bryant

Keyword(s):

Natural Populations ◽

Environmental Variation

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The Key Role of Epigenetics in the Persistence of Asexual Lineages

Genetics Research International ◽

10.1155/2012/534289 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 22

Author(s):

Emilie Castonguay ◽

Bernard Angers

Keyword(s):

Phenotypic Plasticity ◽

Recent Work ◽

Molecular Mechanism ◽

Crucial Role ◽

Environmental Variation ◽

Epigenetic Modifications ◽

Epigenetic Variation ◽

Epigenetic Mechanisms ◽

Evolutionary Persistence

Asexual organisms, often perceived as evolutionary dead ends, can be long-lived and geographically widespread. We propose that epigenetic mechanisms could play a crucial role in the evolutionary persistence of these lineages. Genetically identical organisms could rely on phenotypic plasticity to face environmental variation. Epigenetic modifications could be the molecular mechanism enabling such phenotypic plasticity; they can be influenced by the environment and act at shorter timescales than mutation. Recent work on the asexual vertebrate Chrosomus eos-neogaeus (Pisces: Cyprinidae) provides broad insights into the contribution of epigenetics in genetically identical individuals. We discuss the extension of these results to other asexual organisms, in particular those resulting from interspecific hybridizations. We finally develop on the evolutionary relevance of epigenetic variation in the context of heritability.

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Conservation of erupting ungulate populations on islands – a comment

Rangifer ◽

10.7557/2.23.2.361 ◽

2003 ◽

Vol 23 (2) ◽

pp. 57 ◽

Cited By ~ 2

Author(s):

Anne Gunn ◽

Frank L. Miller ◽

Samuel J. Barry

Keyword(s):

Density Dependence ◽

Rangifer Tarandus ◽

Abiotic Factors ◽

Environmental Variation ◽

Juvenile Survival ◽

Relative Importance ◽

Subsequent Performance ◽

Forage Availability ◽

Over Time

A generalised model for herbivores experiencing abundant forage over time is that their numbers erupt and then decline. This model has been applied to fluctuations in caribou (Rangifer tarandus) populations especially those on islands. Since this generalised model for erupting herbivores was first proposed, two assumptions have slipped in (1) that an erupting population will crash; and (2) that the crash will be density-dependent. The problem with the assumptions is that, without testing, they can lead to inappropriate management such as culls. The first assumption arises from uncritical use of earlier accounts and the second assumption from not discriminating between the effects of environmental variation from the effects of the high herbivore numbers on forage availability (density-dependence). Often typical densitydependent effects such as lowered initial reproduction, reduced early survival of calves, and subsequent calf, yearling and juvenile survival are used to justify the contention that there are too many herbivores. But such reasoning is flawed unless cause/effect relationships are established and the role of environmental variation is evaluated. We argue that it is overly simplistic to believe that every population’s subsequent performance and fate will follow a singular pattern with only one paramount factor driving and ultimately dictating an inevitable outcome. The relative importance of unpredictable abiotic factors in influencing and causing variation in the response of ungulate populations should be investigated, no matter whether those factors are sporadic or periodic.

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