Jeffrey D Karron

Jeffrey D Karron
University of Wisconsin - Milwaukee | UWM · Department of Biological Sciences

PhD

About

51
Publications
11,320
Reads
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3,718
Citations
Additional affiliations
August 2018 - present
University of Wisconsin - Milwaukee
Position
  • Professor (Full)
September 1997 - August 2018
University of Wisconsin - Milwaukee
Position
  • Professor (Associate)
September 1990 - August 1997
University of Wisconsin - Milwaukee
Position
  • Professor (Assistant)

Publications

Publications (51)
Article
Full-text available
. Pollinator abundance is declining worldwide and may lower the quantity and quality of pollination services to flowering plant populations. Loss of an important pollinator is often assumed to reduce the amount of pollen received by stigmas of a focal species (pollination success), yet this assumption has rarely been tested experimentally. The magn...
Article
Full-text available
Most flowering plants are hermaphroditic, yet the proportion of seeds fertilized by self and outcross pollen varies widely among species, ranging from predominant self-fertilization to exclusive outcrossing. A population's rate of outcrossing has important evolutionary outcomes as it influences genetic structure, effective population size, and offs...
Article
Full-text available
Premise: Genetically diverse sibships are thought to increase parental fitness through a reduction in the intensity of sib competition, and through increased opportunities for seedling establishment in spatially or temporally heterogeneous environments. Nearly all research on mate diversity in flowering plants has focused on the number of fathers...
Article
Full-text available
Background Siring success plays a key role in plant evolution and reproductive ecology, and variation among individuals creates an opportunity for selection to act. Differences in male reproductive success can be caused by processes that occur during two stages, the pollination and post-pollination phases of reproduction. In the pollination phase,...
Article
Full-text available
Variation in selfing rates within and among populations of hermaphroditic flowering plants can strongly influence the evolution of reproductive strategies and the genetic structure of populations. This intraspecific variation in mating patterns may reflect both genetic and ecological factors, but the relative importance of these factors remains poo...
Article
Floral sexual polymorphisms have evolved repeatedly in angiosperms and are thought to reduce self-pollination and increase pollen export. Using a powerful pollen-labeling technique, quantum dots, a new study shows that pollen placement on pollinator bodies plays a critical role in disassortative pollination.
Article
Full-text available
Researchers have long assumed that plant spatial location influences plant reproductive success and pollinator foraging behaviour. For example, many flowering plant populations have small, linear or irregular shapes that increase the proportion of plants on the edge, which may reduce mating opportunities through both male and female function. Addit...
Data
FREE PDF available at doi.org/10.1093/aob/mcz159
Article
Full-text available
REVIEW The male fitness pathway, from pollen production to ovule fertilization, is thought to strongly influence reproductive trait evolution in animal-pollinated plants. This pathway is characterized by multiple avenues of pollen loss which may lead to reductions in male fitness. However, empirical data on the mechanistic processes leading to pol...
Article
Pollinator behaviour has profound effects on plant mating. Pollinators are predicted to minimise energetic costs during foraging bouts by moving between nearby flowers. However, a review of plant mating system studies reveals a mismatch between behavioural predictions and pollen-mediated gene dispersal in bird-pollinated plants. Paternal diversity...
Article
Full-text available
Premise of the study: Selfing rates vary widely within and among populations of self-compatible flowering plants. This variation is often attributed to differences in the amount and timing of self and outcross pollen deposition on stigmas, as well as to the influence of postpollination mechanisms that control fertilization success. This study expl...
Conference Paper
Background/Question/Methods Male and female reproductive success can vary strongly with the number of flowers blooming simultaneously on a plant. Plants with many open flowers often attract more pollinator visits, increasing outcross pollen receipt. However, on large displays pollinators frequently visit several flowers in sequence, which may incr...
Article
Full-text available
In many flowering plants individual fruits contain a mixture of half- and full- siblings, reflecting pollination by several fathers. To better understand the mechanisms generating multiple paternity within fruits we present a theoretical framework linking pollen carryover with patterns of pollinator movement. This 'sire profile' model predicts that...
Article
Full-text available
Unlabelled: • Premise of the study: Microsatellite markers were isolated and characterized in Mimulus ringens (Phrymaceae), a herbaceous wetland perennial, to facilitate studies of mating patterns and population genetic structure. • Methods and results: A total of 42 polymorphic loci were identified from a sample of 24 individuals from a singl...
Article
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Spatial separation of male and female reproductive structures (herkogamy) is a widespread floral trait that has traditionally been viewed as an adaptation that reduces the likelihood of self-pollination. Here we propose that increased herkogamy may also influence another important aspect of plant mating: the diversity of pollen donors siring seeds...
Article
Full-text available
Pollinator foraging patterns and the dynamics of pollen transport influence the quality and diversity of flowering plant mating opportunities. For species pollinated by groom-ing pollinators, such as bees, the amount of pollen carried between a donor flower and potential recipient flowers depends on how grooming influences pollen transfer. To inves...
Article
Full-text available
Background The remarkable diversity of mating patterns and sexual systems in flowering plants has fascinated evolutionary biologists for more than a century. Enduring questions about this topic include why sexual polymorphisms have evolved independently in over 100 plant families, and why proportions of self- and cross-fertilization often vary dram...
Article
Full-text available
The number of flowers blooming simultaneously on a plant may have profound consequences for reproductive success. Large floral displays often attract more pollinator visits, increasing outcross pollen receipt. However, pollinators frequently probe more flowers in sequence on large displays, potentially increasing self-pollination and reducing polle...
Article
Full-text available
When co-occurring plant species overlap in flowering phenology they may compete for the service of shared pollinators. Competition for pollination may lower plant reproductive success by reducing the number of pollinator probes or by decreasing the quality of pollen transport to or from a focal species. Pair-wise interactions between plants sharing...
Article
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When exotic plant species share pollinators with native species, competition for pollination may lower the reproductive success of natives by reducing the frequency and/or quality of visits they receive. Exotic species often become numerically dominant in plant communities, and the relative abundance of these potential competitors for pollination m...
Article
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Background: Some of the most exciting advances in pollination biology have resulted from interdisciplinary research combining ecological and evolutionary perspectives. For example, these two approaches have been essential for understanding the functional ecology of floral traits, the dynamics of pollen transport, competition for pollinator service...
Article
Full-text available
Co-flowering plant species frequently share pollinators. Pollinator sharing is often detrimental to one or more of these species, leading to competition for pollination. Perhaps because it offers an intriguing juxtaposition of ecological opposites - mutualism and competition - within one relatively tractable system, competition for pollination has...
Article
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Movement of pollinators between coflowering plant species may influence conspecific pollen deposition and seed set. Interspecific pollinator movements between native and showy invasive plants may be particularly detrimental to the pollination and reproductive success of native species. We explored the effects of invasive Lythrum salicaria on the re...
Article
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Adjacent flowers on Mimulus ringens floral displays often vary markedly in selfing rate. We hypothesized that this fine-scale variation in mating system reflects the tendency of bumble-bee pollinators to probe several flowers consecutively on multiflower displays. When a pollinator approaches a display, the first flower probed is likely to receive...
Article
Full-text available
The timing and effectiveness of pollinator visitation to flowers is an important factor influencing mating patterns and reproductive success. Multiple pollinator probes to a flower may increase both the quantity and genetic diversity of progeny, especially if single probes deposit insufficient pollen for maximal seed set or if the interval between...
Article
Full-text available
Multiply sired fruits provide unambiguous evidence that pollen from two or more donors was deposited on a stigma and successfully fertilized ovules. Such multiple paternity within fruits can have important consequences for both parental and offspring fitness, but little is known about the frequency of multiple paternity or the mechanisms causing it...
Article
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Sympatric plant species with similar flowering phenologies and floral mor-phologies may compete for pollination, and as a consequence potentially influence each other's reproductive success and mating system. Two likely competitors are Mimulus ringens and Lobelia siphilitica, which co-occur in wet meadows of central and eastern North Amer-ica, prod...
Article
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Pollinators often visit several flowers in sequence on plants with large floral displays. This foraging pattern is expected to influence the rate of self-fertilization in self-compatible taxa. To quantify the effects of daily floral display on pollinator movements and selfing, we experimentally manipulated flower number in four replicate (cloned) a...
Article
Full-text available
1. Pollinators visiting large floral displays may probe several flowers in sequence, leading to geitonogamous (among-flower) self-pollination. To investigate the relationship between floral display size and patterns of pollinator movement, we studied foraging by several pollinator species in four replicate arrays of Mimulus ringens (Scrophulariacea...
Article
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Most parasitic dwarf mistletoes (Arceuthobium spp.) are dioecious and can parasitize more than one species of conifer host. In Colorado, Arceuthobium americanum Nutt. has Pinus contorta Dougl. as one of its principal hosts and Pinus ponderosa Laws. var. scopulorum Engelm. as a secondary host. Arceuthobium vaginatum Willd. subsp. cryptopodum (Engelm...
Article
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The endangered great ape, Pan paniscus (bonobo) has the smallest range of the African apes. Virtually nothing is known about the genetic diversity or genetic structure of this species, while substantial amounts of polymorphism have been reported for the bonobo's widespread congener, the chimpanzee (P. troglodytes). Given its restricted range, what...
Article
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Anther–stigma separation (herkogamy) is highly variable within populations of Mimulus ringens, a bumblebee-pollinated perennial herb with a mixed-mating system. The relationship between this floral trait and individual outcrossing rates was studied in two experimental populations composed of genets with unique multilocus combinations of homozygous...
Chapter
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The term ‘rarity’ has been applied to species with diverse patterns of distribution and abundance (Chapter 3; Drury, 1974, 1980; Harper, 1981; Rabinowitz, 1981; Fiedler and Ahouse, 1992; Kunin and Gaston, 1993; Gaston, 1994). For example, localized endemics have small geographical distributions but often occur at high population density, whereas sp...
Article
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We compared the vocal repertoires of Jackass (Spheniscus demersus), Humboldt (S. humboldti), and Magellanic (S. magellanicus) penguins. Discriminant and cluster analyses of the bray call indicate that Jackass and Magellanic penguins are more similar to each other than either is to the Humboldt penguin, and all three are distinct from the Rockhopper...
Article
Full-text available
Pollinator movements and pollen-mediated gene dispersal were quantified in experimental populations of square-stemmed monkeyflower (Mimulus ringens), a wetland perennial herb with a mixed-mating system. Each population consisted of genets with unique multilocus combinations of homozygous genotypes, facilitating assignment of paternity to all sample...
Article
Full-text available
The influence of population density on pollinator movements and outcrossing rates was studied in experimental arrays of Mimulus ringens (square-stemmed monkeyflower), a wetland perennial species with a mixed-mating system. Each population was composed of genets with unique multi-locus combinations of homozygous genotypes, facilitating determination...
Article
Full-text available
Two hypotheses have been proposed concerning possible fitness advantages of multiple paternity. According to the Elbow Room hypothesis, the magnitude of resource partitioning is positively correlated with the genetic diversity of competitors. This leads to the prediction that the mean fitness of competing half-siblings will exceed the mean fitness...
Article
Full-text available
Two hypotheses have been proposed concerning possible fitness advantages of multiple paternity. According to the Elbow Room hypothesis, the magnitude of resource partitioning is positively correlated with the genetic diversity of competitors. This leads to the prediction that the mean fitness of competing half-siblings will exceed the mean fitness...
Article
Full-text available
To estimate the numbers of sporophytic S-alleles in two adjacent populations of wild radish, we performed 701 reciprocal crosses among 50 individuals. Each cross was replicated five times in each direction. Sixteen plants were fully intercompatible, indicating the presence of at least 32 S-alleles in the two populations. A minimum of 22 S-alleles o...
Article
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In natural populations, wild radish plants typically mate with 6-8 pollen donors, and seeds of individual fruits are usually sired by 1-4 fathers. Since radish fruits are indehiscent and gravity-dispersed, progeny are most likely to compete with a mixture of full and half siblings. The fitness consequences of single and multiple paternity were inve...
Article
Full-text available
In natural populations, wild radish plants typically mate with 6-8 pollen donors, and seeds of individual fruits are usually sired by 1-4 fathers. Since radish fruits are indehiscent and gravity-dispersed, progeny are most likely to compete with a mixture of full and half siblings. The fitness consequences of single and multiple paternity were inve...
Article
Full-text available
Both restricted A. linifolius and restricted A. osterhouti are self-compatible, and A. linifolius is moderately autogamous. Widespread A. lonchocarpus is self-compatible, but widespread A. pectinatus is essentially self-incompatible. Neither the restricted nor the widespread species exhibited evidence of fecundity components of inbreeding depressio...
Article
Full-text available
Several workers have suggested that species with restricted ranges and few individuals are more likely to be self-compatible and to exhibit low levels of inbreeding depression than are geographically widespread congeners. To investigate these predicted patterns, controlled pollinations were performed in the field on populations of two restricted an...
Article
Full-text available
Evolutionary theory predicts that species with small ranges and few individuals will exhibit low levels of genetic polymorphism. We investigated the population genetic structure of two locally endemic and two geographically widespread species of Astragalus. To facilitate direct comparisons among these congeners, three populations of each species we...
Article
Full-text available
Evolutionary theory predicts that species with small ranges and few individuals will exhibit low levels of genetic polymorphism. We investigated the population genetic structure of two locally endemic and two geographically widespread species of Astragalus. To facilitate direct comparisons among these congeners, three populations of each species we...
Article
Full-text available
Astragalus linifolius and Astragalus osterhouti are geographically restricted legume species, with total ranges of less than 60 km2. Each of these xerophytic, shrubby perennials co-occurs with a widespread congener: A. linifolius with A. lonchocarpus and A. osterhouti with A. pattersoni. All four species exhibit similar floral size, colour and morp...
Article
Full-text available
Evolutionary theory predicts low levels of genetic polymorphism and high levels of self-compatibility in plant species with small ranges and few individuals. To test these predictions, I compared published data on electrophoretically detectable genetic variation and breeding systems for geographically restricted and widespread congeners in eleven g...