The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 1. Reproductive correlates of floral variation

Herrera, Carlos M.

doi:10.1111/j.1095-8312.1990.tb00539.x

Cited by 38 publications

(35 citation statements)

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“…r Ͻ 0.50 Price and Boag 1987). Spur length was included in the analyses because it was the only floral character measured (except for the nectar traits, see below) and flower depth has been found to be sensitive to selection in several plants ( Nilsson 1988;Schemske and Horvitz 1989;Steiner and Whitehead 1990;Campbell 1991;Johnson and Steiner 1997; but see Herrera 1990). In addition, there are clear patterns of differentiation in spur length among northern European P. bifolia populations, with the spur length varying geographically with the pollinator tongue length (L. A.…”

Section: Choice Of Characters In Analysesmentioning

confidence: 99%

“…Schemske and Horvitz (1989) found selection for less flower depth in bee-pollinated Calathea ovandensis in one of three years. However, Herrera (1990Herrera ( , 1993 found no selection on spur length in natural populations of the hawkmoth-pollinated V. cazorlensis.…”

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confidence: 94%

“…Favorably, PPR gives new opportunities to explore and visualize any multidimensional selection surface, but has up to now not been used on reproductive plant traits. Herrera (1990) investigated the shape of a selection curve of a floral character (spur length) in the hawkmoth-pollinated Viola cazorlensis by using a cubic spline method-a similar but univariate curve-fitting method (for details, see Schluter 1988).…”

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confidence: 99%

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PHENOTYPIC SELECTION IN HAWKMOTH-POLLINATEDPLATANTHERA BIFOLIA:TARGETS AND FITNESS SURFACES

Maad

2000

Evolution

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Abstract. The present study explored phenotypic selection on phenological and morphological reproductive traits in hawkmoth-pollinated Platanthera bifolia (Orchidaceae), a Eurasian perennial herb displaying bisexual, long-spurred flowers. The work was carried out during three flowering seasons (1993)(1994)(1995) in a Swedish population. Fitness was estimated as the number of pollinia removed (male fitness) and fruits produced (female fitness). Targets and patterns of selection were compared between years and sex functions by the use of multiple linear regression (including correlational selection estimates, i.e., of combination of traits), analysis of covariance, and projection pursuit regression (PPR). Results from the nonparametric surface-fitting-method PPR showed that selection was mostly linear, thus justifying the use of the parametric methods. In all study years, male and female fitness were highest in plants with many flowers. This reflects that flower number sets an upper limit to fitness and that a large inflorescence attracts more pollinators. In 1994, the summer was dry and the average spur length of P. bifolia was shorter than in the other years. In this year, male and female fitness were positively related to spur length, apparently because the spur of short-spurred plants was somewhat too short relative to the tongue length of the local pollinator for optimal pollen export and import. Additionally, the dry weather in 1994 caused a tendency for correlational selection, which was not found in the other years of study. Among small individuals (apparently more sensitive to drought than large ones), early-flowering plants had higher male and female fitness. The results show that patterns of selection may vary both between years and between sex functions in perennial hermaphroditic plants. The present study is one of the first to consider correlational selection in plants, which probably is of common occurrence and deserves to be investigated more.Key words. Correlational selection, curvature selection, female fitness, hawkmoths, male fitness, orchids, phenotypic selection, plant reproduction, pollination, projection, selection surfaces.Received August 3, 1998. Accepted July 16, 1999. Since the foundation of evolutionary biology, natural selection mediated by pollinators has been considered to have shaped the great diversity in floral variation among angiosperms (Darwin 1862). Indeed, pollinator-mediated selection has been documented in a number of recent studies (e.g.,

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Section: Choice Of Characters In Analysesmentioning

confidence: 99%

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PHENOTYPIC SELECTION IN HAWKMOTH-POLLINATEDPLATANTHERA BIFOLIA:TARGETS AND FITNESS SURFACES

Maad

2000

Evolution

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“…However, in the literature, tbere are examples of botb consistency of pollination ecotypes related to proboscis lengtb (e.g. Robertson & Wyatt, 1990, for butterflies;Suzuki, 1992, for bees), and independence between tbem, even for species witb flower tubes mucb longer tban N. tazetta (Herrera, 1990a). In any case, wbile we bave no adaptational explanation for tbe longer tubes in bill populations, we can suggest that tbese plants are not selected against in relation to tbe rewards for nectar-seeking insects.…”

Section: Floral Morphology and Pollination Ecotypesmentioning

confidence: 99%

Variations in habitat, season, flower traits and pollinators in dimorphic Narcissus tazetta L. (Amaryllidaceae) in Israel

1995

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S U M M A H YNarcissus tazelta shows a genetically-based discrete polytnorphism for style letigth sitnilar to that well known in heterostylous plants. Plants are either short-(S) or long-styled (L). In Israel, marsh populatiotis are dominated by S plants and hill populations by L plants. Populations difTer in size, flowering time and duration, flower orientation, inflorescence display, vegetative reproduction, and pollinators. The main visitors to flowers in marshes are hawkmoths, whereas in the hills they are visited by short-tongued insects : solitary bees and hoverflies. The pollination efficiency of these itisects was itivestigated by studying foraging behaviour, visit rate, and pollen deposition on stigmas. Our findings are consistent with the hypothesis of lower efficiency of pollination of S flowers by short-tongued itisccts, resulting in the exclusion of this morph from the hills. Additionally, we cotisidcred the possibility that there might be pollination ecotypes corresponding to the two habitats (marsh and hill) and examined variatioti in a set of continuous flower traits related to pollination biology. Flower tube length was the only trait showing a distinct diflerence between the two habitat types. .'Vlthough the concentration of nectar was not different betweeti habitats, L Bowers presetited tnore concentrated nectar than S flowers. Such a difference in nectar concentration may be of adaptive value for the pollination ofthe L flowers by short-tongued pollinators in the hills.

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“…One possible approach to test the adaptiveness of floral traits is to ask if individual variation translates into differential reproductive success (Harding, 1970;Waser & Price, 1981;Thomson & Stratton, 1985;Stanton, Snow & Handel, 1986;Stanton & Preston, 1988;Nilsson, 1988;Galen & Newport, 1988;Herrera, 1990b). O n the other hand, where significant floral variation occurs between populations, a further approach would consist of examining whether this variation correlates with changes in the identity of pollinators.…”

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The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 2. Patterns of variation among disjunct populations

Herrera¹

1990

Biological Journal of the Linnean Society

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This study examines patterns of variation in quantitative floral traits among 18 disjunct populations of Viola cazorlensis (Violaceae), a relict endemic violet of south-eastern Spain. At all sites, the species is almost exclusively pollinated by a single species of day-flying hawkmoth. Differences between populations were significant for all traits examined, and population means exhibit a broad range of variation. When all characters are considered together, each population displays a unique combination of characters. Despite interpopulation differences in character means, local populations retain most of the variability of the entire species. Floral traits d o not vary in unison among flowers, and at least four different subsets of independently varying traits are identifiable. Floral similarity between populations of V. cazorlensis was largely unrelated to geographic proximity, as revealed by analyses at both large and small geographic scales. The geographic pattern of floral variation among populations represents a random patchwork, with unique combinations of character means occurring randomly across the study region. Marked population differences in quantitative floral traits in spite of spatial constancy in the identity of pollinators, a disintegrated floral phenotype, and prevailingly random geographic variation among populations, suggest low adaptedness of the floral phenotype of V. cazorlensir to its current hawkmoth pollinators.

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The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 1. Reproductive correlates of floral variation

Cited by 38 publications

References 35 publications

PHENOTYPIC SELECTION IN HAWKMOTH-POLLINATEDPLATANTHERA BIFOLIA:TARGETS AND FITNESS SURFACES

PHENOTYPIC SELECTION IN HAWKMOTH-POLLINATEDPLATANTHERA BIFOLIA:TARGETS AND FITNESS SURFACES

Variations in habitat, season, flower traits and pollinators in dimorphic Narcissus tazetta L. (Amaryllidaceae) in Israel

The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 2. Patterns of variation among disjunct populations

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