Evolution in closely adjacent plant populations VIII. Clinal patterns at a mine boundary
TL;DR: The morphological characters of plants of the grass Anthoxant hum odoratum L. odoratum taken from sites along a transect across a mine/pasture boundary were investigated and concluded that in general tolerant plants had smaller flowers, smaller leaves and thinner stems.
Abstract: SEVERAL previous papers in this series have been concerned with the evolution of differences between tolerant and non-tolerant populations of grasses growing over the boundaries of mine tip and pasture soils (Jam and Bradshaw, 1966, McNeilly and Antonovics, 1968, Antonovics, 1968a). Metal tolerant plants differ both physiologically and morphologically from normal plants in several features other than tolerance. Differences in calcium and phosphate response are recorded by Jowett (1959) and McNeilly (1966); Turner (1967) has shown differences in sulphur response; and Schwanitz and Hahn (1 954a, 1 954b) showed from a study of a range of plant species grown under standard conditions that in general tolerant plants had smaller flowers, smaller leaves and thinner stems. This was confirmed for Silene inflata by Broker (1963) who concluded from segregating progenies that dwarfness was not linked to tolerance and had probably been selected independently. Similarly, morphological differences have been recorded in the grass Agrostis tenuis on lead mines (Bradshaw, 1959; Jowett, 1964) and copper mines (McNeiIly, 1966). The morphological characters of plants of the grass Anthoxant hum odoratum L. taken from sites along a transect across a mine/pasture boundary were investigated with three main points in view.
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TL;DR: The effects of genetic drift, inbreeding, and gene flow on genetic diversity and fitness in rare plants and small populations and those circumstances that are likely to put these plant species and populations at genetic risk are identified.
Abstract: Although the potential genetic risks associated with rare or endangered plants and small populations have been discussed previously, the practical role of population genetics in plant conservation remains unclear. Using theory and the available data, we examine the effects of genetic drift, inbreeding, and gene flow on genetic diversity and fitness in rare plants and small populations. We identify those circumstances that are likely to put these plant species and populations at genetic risk. Warning signs that populations may be vulnerable include changes in factors such as population size, degree of isolation, and fitness. When possible, we suggest potential management strategies.
2,485 citations
TL;DR: Here it is reviewed the literature on phenological patterns of germination, flowering, and fruiting (including dispersal) of plants during the seasonal timing of life cycle events.
Abstract: The term phenology is derived from the Greek word phaino meaning to show or to appear. Hence, phenology is defined as the study of the seasonal timing of life cycle events. For plants the seasonal timing of such events can be critical to survival and reproduction. In agriculture the most common failure of introduced crops is the inability to adjust to the seasons imposed by the new, environment (68). In the past few years, interest in the ecology and evolution of timing of life cycle events has grown. Here we review the literature on phenological patterns of germination, flowering, and fruiting (including dispersal).
1,458 citations
TL;DR: In this paper, the authors illustrate the literature on those plants and micro-organisms which can combat excessive quantities of heavy metal ions, which are poisonous and can cause death of most living organisms.
Abstract: Publisher Summary This chapter illustrates the literature on those plants and micro-organisms which can combat excessive quantities of heavy metal ions. Heavy metals include those metals which have density greater than five. Their common feature in regard to biological life is that in excessive quantities they are poisonous and can cause death of most living organisms. However, certain organisms possess an ability to survive under conditions of metal contamination which can prove toxic to other living things. Toxic levels of heavy metals can occur under several circumstances. The chapter focuses on the type of contamination in which the soil itself contains large quantities of these metals. The contamination results from the presence of undisturbed metal ore near the soil surface causing anomalies or from the actual mining of ore bodies. The vegetation in such areas is influenced by one overriding factor, namely, metal concentration. The habitats are usually spatially distinct and clear cut. It is observed that the sequence and pattern of genetic change responsible for colonization of metal-contaminated areas serves as a unique record of natural selection in action.
1,209 citations
TL;DR: The dimensions and nature of the Earth's terrestrial biodiversity are examined, and the scientific facts concerning the rate of loss of biodiversity and the drivers of this loss are reviewed.
Abstract: ▪ Abstract Biodiversity, a central component of Earth's life support systems, is directly relevant to human societies. We examine the dimensions and nature of the Earth's terrestrial biodiversity and review the scientific facts concerning the rate of loss of biodiversity and the drivers of this loss. The estimate for the total number of species of eukaryotic organisms possible lies in the 5–15 million range, with a best guess of ∼7 million. Species diversity is unevenly distributed; the highest concentrations are in tropical ecosystems. Endemisms are concentrated in a few hotspots, which are in turn seriously threatened by habitat destruction—the most prominent driver of biodiversity loss. For the past 300 years, recorded extinctions for a few groups of organisms reveal rates of extinction at least several hundred times the rate expected on the basis of the geological record. The loss of biodiversity is the only truly irreversible global environmental change the Earth faces today.
1,157 citations
Cites background from "Evolution in closely adjacent plant..."
...A classic example here is the differentiation of plants that have invaded tailings from abandoned mines (32)....
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TL;DR: A literature review of the world's most important food crops shows that 12 of these crops hybridize with wild relatives in some part of their agricultural distribution, and suggests ways of assessing the likelihood of hybridization, introgression, and the potential for undesirable gene flow from crops into weeds or rare species.
Abstract: ▪ Abstract Domesticated plant taxa cannot be regarded as evolutionarily discrete from their wild relatives. Most domesticated plant taxa mate with wild relatives somewhere in the world, and gene flow from crop taxa may have a substantial impact on the evolution of wild populations. In a literature review of the world's 13 most important food crops, we show that 12 of these crops hybridize with wild relatives in some part of their agricultural distribution. We use population genetic theory to predict the evolutionary consequences of gene flow from crops to wild plants and discuss two applied consequences of crop-to-wild gene flow–the evolution of aggressive weeds and the extinction of rare species. We suggest ways of assessing the likelihood of hybridization, introgression, and the potential for undesirable gene flow from crops into weeds or rare species.
928 citations
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TL;DR: The relation between the intensity of selection, the mean distance migrated per generation, and the slope of the cline can be calculated and is used for a provisional calculation of intensities of selection in a population of Peromyscus polionotus.
Abstract: Where one phenotype is favoured in one area and another phenotype in a neighbouring area, the character in question may be expected to show a cline in the neighbourhood of the boundary. On certain assumptions the relation between the intensity of selection, the mean distance migrated per generation, and the slope of the cline can be calculated. The relation is used for a provisional calculation of intensities of selection in a population ofPeromyscus polionotus. These have the very low value of about 0.1%.
481 citations
TL;DR: The evidence and the theoretical analysis show that divergence among adjacent plant populations I is driven by different evolutionary mechanisms, and the evidence and its theoretical analysis are consistent with this view.
Abstract: Evolutionary divergence among adjacent plant populations I. The evidence and its theoretical analysis
429 citations
TL;DR: Evolution in closely adjacent plant populations III.
Abstract: Evolution in closely adjacent plant populations III. Agrostis tenuis on a small copper mine
295 citations
274 citations