Repeated exposure to enhanced UV‐B radiation in successive generations increases developmental instability (leaf fluctuating asymmetry) in a desert annual

Abstract

Populations of the desert annual Dimorphotheca sinuata, derived from a common seed stock, were exposed concurrently over four successive generations to either ambient (representing no stratospheric ozone depletion) or elevated (representing 20% stratospheric ozone depletion) UV-B levels during their complete life cycle. Leaf fluctuating asymmetry (FA) was measured in populations of plants grown from seeds of selected generations which had experienced different UV-B exposure histories, and from seeds collected from a wild population of this species which grows in a naturally enhanced UV-B environment. These measured plants had been grown in a greenhouse under essentially UV-B-free conditions. Leaf FA was significantly increased by greater numbers of enhanced UV-B exposures in the parentage of the seed. There was a linear to exponential dose-response relationship between number of UV-B exposure iterations in seed parentage and leaf FA, suggesting that damage to DNA caused by UV-B exposure during plant development may not be fully repaired, and thus be inherited by offspring and accumulated over successive generations in this species. Leaf FA of plants grown from seed from the wild population was not significantly greater than that of control plants whose parentage experienced only ambient UV-B exposures, although this negative result may have been due to low sampling intensity and measurement resolution, and the relatively low UV-B enhancement experienced by the wild population. We conclude that leaf FA may constitute a relatively sensitive yet inexpensive means of quantifying UV-B damage to plants.

Carry‐over of enhanced ultraviolet‐B exposure effects to successive generations of a desert annual: interaction with atmospheric CO2 and nutrient supply

“…These findings are corroborated by evidence of a progressive alteration in offspring performance with cumulative generations of enhanced UV‐B exposure. Also, they are supported by previously published findings of a simple linear dose–response relationship between the number of enhanced UV‐B exposure iterations in seed parentage of offspring and their leaf fluctuating asymmetry, an indirect measure of developmental instability indicating genetic damage ( Midgley et al . 1998 ).…”

Geographical variation in asymmetry in Gasterosteus aculeatus

“…Previous studies have found elevated levels of FA in organisms subjected to stress during embryonic development, including acidic conditions (Jagoe & Haines, 1985; Ostbye et al , 1997; Mazzi & Bakker, 2001), exposure to UV radiation (Midgley et al , 1998), food deprivation (Swaddle & Witter, 1994; Roy & Stanton, 1999; Stoks, 2001) and temperature fluctuations (Beardmore, 1960; Gest et al ., 1986; Clarke & McKenzie, 1992; Leary et al , 1992; Hosken et al ., 2000). Since these factors can generate FA in newly emerging young, we expected to see elevated FA in juvenile stickleback in the small bog lakes of the lowlands, as these are acidic, dystrophic and shallow.…”

Potential vulnerability of Namaqualand plant diversity to anthropogenic climate change

“…It is also interesting to note that the Namaqualand annuals Dimorphotheca pluvialis and Dimorphotheca sinuata show some resilience of both growth and reproductive output under elevated UV-b levels, and little impact on these performance measures by elevated CO 2 levels (Wand et al, 1996), although there is some evidence to suggest a gradual accumulation of genetic damage under these conditions (Midgley et al, 1998;Musil, 1996;Musil et al, 1999). Therefore, although succulent species may be susceptible to climate change impacts, it is very likely that other plant growth forms will be more resilient, and may at least persist or even thrive under changing conditions.…”