1
|
Sgambelluri LR, Jarvis JC, Kamel SJ. Multiple paternity, fertilization success, and male quality: Mating system variation in the eelgrass, Zostera marina. Ecol Evol 2024; 14:e11608. [PMID: 38919644 PMCID: PMC11197038 DOI: 10.1002/ece3.11608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 05/31/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024] Open
Abstract
Genetic diversity can modulate a population's response to a changing environment and plays a critical role in its ecological function. While multiple processes act to maintain genetic diversity, sexual reproduction remains the primary driving force. Eelgrass (Zostera marina) is an important habitat-forming species found in temperate coastal ecosystems across the globe. Recent increases in sea surface temperatures have resulted in shifts to a mixed-annual life-history strategy (i.e., displaying characteristics of both annual and perennial meadows) at its southern edge-of-range. Given that mating systems are intimately linked to standing levels of genetic variation, understanding the scope of sexual reproduction can illuminate the processes that shape genetic diversity. To characterize edge-of-range eelgrass mating systems, developing seeds on flowering Z. marina shoots were genotyped from three meadows in Topsail, North Carolina. In all meadows, levels of multiple mating were high, with shoots pollinated by an average of eight sires (range: 3-16). The number of fertilized seeds (i.e., reproductive success) varied significantly across sires (range: 1-25) and was positively correlated with both individual heterozygosity and self-fertilization. Outcrossing rates were high (approx. 70%) and varied across spathes. No clones were detected, and kinship among sampled flowering shoots was low, supporting observed patterns of reproductive output. Given the role that genetic diversity plays in enhancing resistance to and resilience from ecological disturbance, disentangling the links between life history, sexual reproduction, and genetic variation will aid in informing the management and conservation of this key foundation species.
Collapse
Affiliation(s)
- Lauren R. Sgambelluri
- Department of Biology and Marine Biology, Center for Marine ScienceUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
| | - Jessie C. Jarvis
- Department of Biology and Marine Biology, Center for Marine ScienceUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
| | - Stephanie J. Kamel
- Department of Biology and Marine Biology, Center for Marine ScienceUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
| |
Collapse
|
2
|
Shelton WR, Mitchell RJ, Christopher DA, Jack LP, Karron JD. Among-individual variation in flowering phenology affects flowering synchrony and mating opportunity. AMERICAN JOURNAL OF BOTANY 2024; 111:e16269. [PMID: 38126922 DOI: 10.1002/ajb2.16269] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 12/23/2023]
Abstract
PREMISE The timing and pattern of a plant's flowering can have important consequences for reproductive success. Variation in flowering phenology may influence the number of prospective mates, the risk of mating with lower quality individuals, and the likelihood of self-pollination. Here we use a common garden experiment to explore within- and among-population variation in phenology. Our work provides new insights into how flowering phenology shapes mating opportunity and flowering synchrony in a self-compatible perennial. METHODS To quantify variation in flowering phenology we raised progeny from nine populations of Mimulus ringens in a common garden. For each individual, we measured phenological traits including age at flowering onset, daily floral display size, total flower number, and flowering synchrony with other members of the population, and related these traits to mating opportunity. We also tested how individual flowering schedules influence the magnitude of synchrony. RESULTS Flowering phenology and synchrony varied substantially within and among populations. From day to day, plants often oscillated between large and small daily floral displays. Additionally, flowering schedules of individual plants strongly influenced flowering synchrony and, along with the number of flowering days, markedly affected plants' mating opportunity. CONCLUSIONS Phenological traits such as flowering synchrony can affect the quantity of mating opportunities and may be important targets of natural selection. Our results highlight the need for studies that quantify flowering patterns of individuals as well as populations.
Collapse
Affiliation(s)
- Wendy R Shelton
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA
| | | | - Dorothy A Christopher
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA
- Department of Biology, Western Connecticut State University, Danbury, Connecticut, 06810, USA
| | - Loretha P Jack
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA
| | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA
| |
Collapse
|
3
|
Tian H, Harder LD, Wang A, Zhang D, Liao W. Habitat effects on reproductive phenotype, pollinator behavior, fecundity, and mating outcomes of a bumble bee-pollinated herb. AMERICAN JOURNAL OF BOTANY 2022; 109:470-485. [PMID: 35244204 PMCID: PMC9314043 DOI: 10.1002/ajb2.1826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
PREMISE Fecundity and mating outcomes commonly differ among plant populations occupying contrasting environments. If self-pollination occurs primarily among flowers within plants, contrasting reproductive outcomes among populations must reflect environmental effects on plant-pollinator interactions. Specifically, local conditions could affect features of plant phenotypes that influence pollinator behavior, in turn modifying plant reproductive outcomes. METHODS We compared phenotypes, pollinator abundance and behavior, and female fecundity and mating in two meadow populations and two forest populations of Aconitum kusnezoffii within 3 km of each other. Mating outcomes were assessed using microsatellites. RESULTS Meadow plants generally produced more, shorter ramets with more, larger flowers, but less nectar per flower than forest plants. These differences likely largely represent phenotypic plasticity. Individual bumble bees visited more flowers on forest plants, likely because the more abundant bees in the meadows depleted nectar availability, as indicated by briefer visits to individual flowers. Despite similar fruit set in both habitats, forest plants set more seeds per fruit. Nevertheless, meadow plants produced more seeds overall, owing to sevenfold greater flower production. Consistent with individual bees visiting fewer flowers on meadow plants, more of their seeds were outcrossed. However, the outcrossed seeds of forest plants included more male mates. CONCLUSIONS Reproductive outcomes can vary among populations of animal-pollinated plants as a result of differences in the availability of effective pollinators and environmental effects on plant phenotypes, and their functional consequences for pollinator behavior that governs pollen dispersal.
Collapse
Affiliation(s)
- Hao Tian
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| | - Lawrence D. Harder
- Department of Biological SciencesUniversity of CalgaryCalgaryAlbertaT2N 1N4Canada
| | - Ai‐Ying Wang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| | - Da‐Yong Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| | - Wan‐Jin Liao
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| |
Collapse
|
4
|
Christopher DA, Karron JD, Semski WR, Smallwood PA, Trapnell DW, Mitchell RJ. Selfing rates vary with floral display, pollinator visitation and plant density in natural populations of Mimulus ringens. J Evol Biol 2021; 34:803-815. [PMID: 33704852 PMCID: PMC8252063 DOI: 10.1111/jeb.13781] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 02/01/2021] [Accepted: 02/25/2021] [Indexed: 11/27/2022]
Abstract
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 poorly understood. Here, we explore how selfing in 13 natural populations of the perennial wildflower Mimulus ringens is influenced by (a) pollinator visitation, an ecological factor, and (b) floral display, a trait with a genetic component that also responds to environmental variation. We also explore whether genetically based floral traits, including herkogamy, affect selfing. We found substantial variation among populations in selfing rate (0.13–0.55). Selfing increased strongly and significantly with floral display, among as well as within populations. Selfing also increased at sites with lower pollinator visitation and low plant density. However, selfing was not correlated with floral morphology. Overall, these results suggest that pollinator visitation and floral display, two factors that interact to affect geitonogamous pollinator movements, can influence the selfing rate. This study identifies mechanisms that may play a role in maintaining selfing rate variation among populations.
Collapse
Affiliation(s)
- Dorothy A Christopher
- Department of Biological Sciences, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
| | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
| | - Wendy R Semski
- Department of Biological Sciences, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
| | | | | | | |
Collapse
|
5
|
Christopher DA, Mitchell RJ, Trapnell DW, Smallwood PA, Semski WR, Karron JD. Edge effects and mating patterns in a bumblebee-pollinated plant. AOB PLANTS 2020; 12:plaa033. [PMID: 32742630 PMCID: PMC7384318 DOI: 10.1093/aobpla/plaa033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
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. Additionally, plants that rely on pollinators may be particularly vulnerable to edge effects if those pollinators exhibit restricted foraging and pollen carryover is limited. To explore the effects of spatial location (edge vs. interior) on siring success, seed production, pollinator foraging patterns and pollen-mediated gene dispersal, we established a square experimental array of 49 Mimulus ringens (monkeyflower) plants. We observed foraging patterns of pollinating bumblebees and used paternity analysis to quantify male and female reproductive success and mate diversity for plants on the edge versus interior. We found no significant differences between edge and interior plants in the number of seeds sired, mothered or the number of sires per fruit. However, we found strong differences in pollinator behaviour based on plant location, including 15 % lower per flower visitation rates and substantially longer interplant moves for edge plants. This translated into 40 % greater pollen-mediated gene dispersal for edge than for interior plants. Overall, our results suggest that edge effects are not as strong as is commonly assumed, and that different plant reproduction parameters respond to spatial location independently.
Collapse
Affiliation(s)
- Dorothy A Christopher
- Department of Biological Sciences, University of Wisconsin–Milwaukee, Milwaukee, WI, USA
| | | | | | | | - Wendy R Semski
- Department of Biological Sciences, University of Wisconsin–Milwaukee, Milwaukee, WI, USA
| | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin–Milwaukee, Milwaukee, WI, USA
| |
Collapse
|
6
|
Christopher DA, Mitchell RJ, Karron JD. Pollination intensity and paternity in flowering plants. ANNALS OF BOTANY 2020; 125:1-9. [PMID: 31586397 PMCID: PMC6948204 DOI: 10.1093/aob/mcz159] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/06/2019] [Accepted: 10/01/2019] [Indexed: 05/10/2023]
Abstract
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, heritable variation in floral traits and floral display affect pollinator visitation patterns, which in turn affect variation among plants in the amount of pollen exported and deposited on recipient stigmas. In the post-pollination phase, differences among individuals in pollen grain germination success and pollen tube growth may cause realized paternity to differ from patterns of pollen receipt. The maternal plant can also preferentially provision some developing seeds or fruits to further alter variation in siring success. SCOPE In this review, we describe studies that advance our understanding of the dynamics of the pollination and post-pollination phases, focusing on how variation in male fitness changes in response to pollen limitation. We then explore the interplay between pollination and post-pollination success, and how these processes respond to ecological factors such as pollination intensity. We also identify pressing questions at the intersection of pollination and paternity and describe novel experimental approaches to elucidate the relative importance of pollination and post-pollination factors in determining male reproductive success. CONCLUSIONS The relative contribution of pollination and post-pollination processes to variation in male reproductive success may not be constant, but rather may vary with pollination intensity. Studies that quantify the effects of pollination and post-pollination phases in concert will be especially valuable as they will enable researchers to more fully understand the ecological conditions influencing male reproductive success.
Collapse
Affiliation(s)
- Dorothy A Christopher
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | | | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| |
Collapse
|
7
|
Christopher DA, Mitchell RJ, Trapnell DW, Smallwood PA, Semski WR, Karron JD. Hermaphroditism promotes mate diversity in flowering plants. AMERICAN JOURNAL OF BOTANY 2019; 106:1131-1136. [PMID: 31403705 PMCID: PMC6852098 DOI: 10.1002/ajb2.1336] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 06/04/2019] [Indexed: 05/12/2023]
Abstract
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 siring seeds within a fruit or on a maternal plant. Yet as hermaphrodites, plants can also accrue mate diversity by siring offspring on several pollen recipients in a population. Here we explore whether mate composition overlaps between the dual sex functions, and discuss the implications for plant reproductive success. METHODS We established an experimental population of 49 Mimulus ringens (monkeyflower) plants, each trimmed to a single flower. Following pollination by wild bees, we quantified mate composition for each flower through both paternal and maternal function. Parentage was successfully assigned to 240 progeny, 98% of the sampled seeds. RESULTS Comparison of mate composition between male and female function revealed high mate diversity, with almost no outcross mates shared between the two sexual functions of the same flower. CONCLUSIONS Dual sex roles contribute to a near doubling of mate diversity in our experimental population of Mimulus ringens. This finding may help explain the maintenance of hermaphroditism under conditions that would otherwise favor the evolution of separate sexes.
Collapse
Affiliation(s)
- Dorothy A. Christopher
- Department of Biological SciencesUniversity of Wisconsin – Milwaukee3209 N. Maryland AveMilwaukeeWisconsin53211USA
| | | | - Dorset W. Trapnell
- Department of Plant BiologyUniversity of Georgia120 Carlton StAthensGeorgia30602USA
| | - Patrick A. Smallwood
- Department of Plant BiologyUniversity of Georgia120 Carlton StAthensGeorgia30602USA
| | - Wendy R. Semski
- Department of Biological SciencesUniversity of Wisconsin – Milwaukee3209 N. Maryland AveMilwaukeeWisconsin53211USA
| | - Jeffrey D. Karron
- Department of Biological SciencesUniversity of Wisconsin – Milwaukee3209 N. Maryland AveMilwaukeeWisconsin53211USA
| |
Collapse
|
8
|
Weber JJ. The messenger matters: Pollinator functional group influences mating system dynamics. Mol Ecol 2019; 26:4113-4115. [PMID: 28792676 DOI: 10.1111/mec.14191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Accepted: 05/18/2017] [Indexed: 11/27/2022]
Abstract
The incredible diversity of plant mating systems has fuelled research in evolutionary biology for over a century. Currently, there is broad concern about the impact of rapidly changing pollinator communities on plant populations. Very few studies, however, examine patterns and mechanisms associated with multiple paternity from cross-pollen loads. Often, foraging pollinators collect a mixed pollen load that may result in the deposition of pollen from different sires to receptive stigmas. Coincident deposition of self- and cross-pollen leads to interesting mating system dynamics and has been investigated in numerous species. But, mixed pollen loads often consist of a diversity of cross-pollen and result in multiple sires of seeds within a fruit. In this issue of Molecular Ecology, Rhodes, Fant, and Skogen () examine how pollinator identity and spatial isolation influence multiple paternity within fruits of a self-incompatible evening primrose. The authors demonstrate that pollen pool diversity varies between two pollinator types, hawkmoths and diurnal solitary bees. Further, progeny from more isolated plants were less likely to have multiple sires regardless of the pollinator type. Moving forward, studies of mating system dynamics should consider the implications of multiple paternity and move beyond the self- and cross-pollination paradigm. Rhodes et al. () demonstrate the importance of understanding the roles that functionally diverse pollinators play in mating system dynamics.
Collapse
|
9
|
Mazer SJ, Hendrickson BT, Chellew JP, Kim LJ, Liu JW, Shu J, Sharma MV. Divergence in pollen performance between Clarkia sister species with contrasting mating systems supports predictions of sexual selection. Evolution 2018; 72:453-472. [PMID: 29359333 DOI: 10.1111/evo.13429] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 01/07/2018] [Accepted: 01/09/2018] [Indexed: 12/22/2022]
Abstract
Animal taxa that differ in the intensity of sperm competition often differ in sperm production or swimming speed, arguably due to sexual selection on postcopulatory male traits affecting siring success. In plants, closely related self- and cross-pollinated taxa similarly differ in the opportunity for sexual selection among male gametophytes after pollination, so traits such as the proportion of pollen on the stigma that rapidly enters the style and mean pollen tube growth rate (PTGR) are predicted to diverge between them. To date, no studies have tested this prediction in multiple plant populations under uniform conditions. We tested for differences in pollen performance in greenhouse-raised populations of two Clarkia sister species: the predominantly outcrossing C. unguiculata and the facultatively self-pollinating C. exilis. Within populations of each taxon, groups of individuals were reciprocally pollinated (n = 1153 pollinations) and their styles examined four hours later. We tested for the effects of species, population, pollen type (self vs. outcross), the number of competing pollen grains, and temperature on pollen performance. Clarkia unguiculata exhibited higher mean PTGR than C. exilis; pollen type had no effect on performance in either taxon. The difference between these species in PTGR is consistent with predictions of sexual selection theory.
Collapse
Affiliation(s)
- Susan J Mazer
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Brandon T Hendrickson
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Joseph P Chellew
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Lynn J Kim
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Jasen W Liu
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Jasper Shu
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Manju V Sharma
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| |
Collapse
|
10
|
Huang Q, Burd M, Fan Z. Resource Allocation and Seed Size Selection in Perennial Plants under Pollen Limitation. Am Nat 2017; 190:430-441. [DOI: 10.1086/692543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
11
|
Rhodes MK, Fant JB, Skogen KA. Pollinator identity and spatial isolation influence multiple paternity in an annual plant. Mol Ecol 2017; 26:4296-4308. [PMID: 28334485 DOI: 10.1111/mec.14115] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/27/2017] [Accepted: 03/01/2017] [Indexed: 11/27/2022]
Abstract
The occurrence and extent of multiple paternity is an important component of variation in plant mating dynamics. However, links between pollinator activity and multiple paternity are generally lacking, especially for plant species that attract functionally diverse floral visitors. In this study, we separated the influence of two functionally distinct floral visitors (hawkmoths and solitary bees) and characterized their impacts on multiple paternity in a self-incompatible, annual forb, Oenothera harringtonii (Onagraceae). We also situated pollinator-mediated effects in a spatial context by linking variation in multiple paternity to variation in plant spatial isolation. We documented pronounced differences in the number of paternal sires as function of pollinator identity: on average, the primary pollinator (hawkmoths) facilitated mating with nearly twice as many pollen donors relative to the secondary pollinator (solitary bees). This effect was consistent for both isolated and nonisolated individuals, but spatial isolation imposed pronounced reductions on multiple paternity regardless of pollinator identity. Considering that pollinator abundance and pollen dispersal distance did not vary significantly with pollinator identity, we attribute variation in realized mating dynamics primarily to differences in pollinator morphology and behaviour as opposed to pollinator abundance or mating incompatibility arising from underlying spatial genetic structure. Our findings demonstrate that functionally distinct pollinators can have strongly divergent effects on polyandry in plants and further suggest that both pollinator identity and spatial heterogeneity have important roles in plant mating dynamics.
Collapse
Affiliation(s)
- Matthew K Rhodes
- Division of Plant Science and Conservation, Chicago Botanic Garden, 1000 Lake Cook Rd, Glencoe, IL, 60022, USA.,Program in Plant Biology and Conservation, Northwestern University, 2205 Tech Drive, O.T. Hogan Hall, Room 2-144, Evanston, IL, 60208, USA
| | - Jeremie B Fant
- Division of Plant Science and Conservation, Chicago Botanic Garden, 1000 Lake Cook Rd, Glencoe, IL, 60022, USA
| | - Krissa A Skogen
- Division of Plant Science and Conservation, Chicago Botanic Garden, 1000 Lake Cook Rd, Glencoe, IL, 60022, USA
| |
Collapse
|
12
|
Mitchell RJ, Wilson WG, Holmquist KG, Karron JD. Influence of pollen transport dynamics on sire profiles and multiple paternity in flowering plants. PLoS One 2013; 8:e76312. [PMID: 24098473 PMCID: PMC3789738 DOI: 10.1371/journal.pone.0076312] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/23/2013] [Indexed: 11/19/2022] Open
Abstract
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 species with more extensive pollen carryover will have a greater number of mates. It also predicts that flowers on large displays, which are often probed consecutively during a single pollinator visitation sequence, will have a lower effective number of mates. We compared these predictions with observed values for bumble bee-pollinated Mimulus ringens, which has restricted carryover, and hummingbird-pollinated Ipomopsis aggregata, which has extensive carryover. The model correctly predicted that the effective number of mates is much higher in the species with more extensive carryover. This work extends our knowledge of plant mating systems by highlighting mechanisms influencing the genetic composition of sibships.
Collapse
Affiliation(s)
- Randall J. Mitchell
- Department of Biology, University of Akron, Akron, Ohio, United States of America
- * E-mail:
| | - William G. Wilson
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Karsten G. Holmquist
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America
| | - Jeffrey D. Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America
| |
Collapse
|
13
|
Hove AA, Mazer SJ. Pollen Performance in Clarkia Taxa with Contrasting Mating Systems: Implications for Male Gametophytic Evolution in Selfers and Outcrossers. PLANTS (BASEL, SWITZERLAND) 2013; 2:248-78. [PMID: 27137375 PMCID: PMC4844357 DOI: 10.3390/plants2020248] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 03/13/2013] [Accepted: 04/03/2013] [Indexed: 12/03/2022]
Abstract
We tested three predictions regarding the joint evolution of pollen performance and mating system. First, due to the potential for intense intrasexual competition in outcrossing populations, we predicted that outcrossers would produce faster-growing pollen than their selfing relatives. Second, if elevated competition promotes stronger selection on traits that improve pollen performance, then, among-plant variation in pollen performance would be lower in outcrossers than in selfers. Third, given successive generations of adaptation to the same maternal genotype in selfers, we predicted that, in selfing populations (but not in outcrossing ones), pollen would perform better following self- than cross-pollinations. We tested these predictions in field populations of two pairs of Clarkia (Onagraceae) sister taxa. Consistent with our predictions, one outcrosser (C. unguiculata) exhibited faster pollen germination and less variation in pollen tube growth rate (PTGR) among pollen donors than its selfing sister species, C. exilis. Contrary to our predictions, the selfing C. xantiana ssp. parviflora exhibited faster PTGR than the outcrossing ssp. xantiana, and these taxa showed similar levels of variation in this trait. Pollen performance following self- vs. cross-pollinations did not differ within either selfing or outcrossing taxa. While these findings suggest that mating system and pollen performance may jointly evolve in Clarkia, other factors clearly contribute to pollen performance in natural populations.
Collapse
Affiliation(s)
- Alisa A Hove
- Biology Department, Warren Wilson College, P.O. Box 9000, Asheville, NC 28815, USA.
| | - Susan J Mazer
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA.
| |
Collapse
|
14
|
Pannell JR, Labouche AM. The incidence and selection of multiple mating in plants. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120051. [PMID: 23339242 DOI: 10.1098/rstb.2012.0051] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mating with more than one pollen donor, or polyandry, is common in land plants. In flowering plants, polyandry occurs when the pollen from different potential sires is distributed among the fruits of a single individual, or when pollen from more than one donor is deposited on the same stigma. Because polyandry typically leads to multiple paternity among or within fruits, it can be indirectly inferred on the basis of paternity analysis using molecular markers. A review of the literature indicates that polyandry is probably ubiquitous in plants except those that habitually self-fertilize, or that disperse their pollen in pollen packages, such as polyads or pollinia. Multiple mating may increase plants' female component by alleviating pollen limitation or by promoting competition among pollen grains from different potential sires. Accordingly, a number of traits have evolved that should promote polyandry at the flower level from the female's point of view, e.g. the prolongation of stigma receptivity or increases in stigma size. However, many floral traits, such as attractiveness, the physical manipulation of pollinators and pollen-dispensing mechanisms that lead to polyandrous pollination, have probably evolved in response to selection to promote male siring success in general, so that polyandry might often best be seen as a by-product of selection to enhance outcross siring success. In this sense, polyandry in plants is similar to geitonogamy (selfing caused by pollen transfer among flowers of the same plant), because both polyandry and geitonogamy probably result from selection to promote outcross siring success, although geitonogamy is almost always deleterious while polyandry in plants will seldom be so.
Collapse
Affiliation(s)
- John R Pannell
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, Lausanne 1015, Switzerland.
| | | |
Collapse
|
15
|
Schaeffer RN, Manson JS, Irwin RE. Effects of abiotic factors and species interactions on estimates of male plant function: a meta-analysis. Ecol Lett 2012; 16:399-408. [DOI: 10.1111/ele.12044] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/16/2012] [Accepted: 11/03/2012] [Indexed: 11/27/2022]
Affiliation(s)
- Robert N. Schaeffer
- Department of Biological Sciences; Dartmouth College; Hanover; NH; 03755; USA
| | | | - Rebecca E. Irwin
- Department of Biological Sciences; Dartmouth College; Hanover; NH; 03755; USA
| |
Collapse
|
16
|
Medrano M, Requerey R, Karron JD, Herrera CM. Herkogamy and mate diversity in the wild daffodil Narcissus longispathus: beyond the selfing-outcrossing paradigm in the evolution of mixed mating. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:801-810. [PMID: 22443123 DOI: 10.1111/j.1438-8677.2012.00569.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
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 within fruits. We test this hypothesis in Narcissus longispathus, a wild daffodil species with extensive variation in anther-stigma separation. To study the morphological basis of variation in herkogamy, floral measurements were undertaken in 16 populations of N. longispathus. We then quantified multilocus outcrossing rates and the correlation of outcrossed paternity in three of these populations sampled over several years. Mating system estimates were calculated for each population and year, and also separately for groups of plants that differed markedly in herkogamy within each population and year. In N. longispathus herkogamy was much more variable than other floral traits, and was more closely related to style length than to anther position. Averaged across populations and years, plants with high herkogamy had similar outcrossing rates (0.683) to plants with intermediate (0.648) or low herkogamy (0.590). However, a significant linear trend was found for correlation of outcrossed paternity, which increased monotonically from high herkogamy (0.221), through intermediate herkogamy (0.303) to low herkogamy (0.463) plants. The diversity of pollen donors siring seeds of high herkogamy Narcissus flowers was thus consistently greater than the diversity of pollen donors siring seeds of low herkogamy flowers. Results of this study contribute to the emerging consensus that floral traits can simultaneously influence several aspects of plant mating system in complex ways, thus extending the traditional focus centred exclusively on patterns and relative importance of self- and cross-fertilisation.
Collapse
Affiliation(s)
- M Medrano
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Isla de La Cartuja, Sevilla, Spain Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - R Requerey
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Isla de La Cartuja, Sevilla, Spain Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - J D Karron
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Isla de La Cartuja, Sevilla, Spain Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - C M Herrera
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Isla de La Cartuja, Sevilla, Spain Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| |
Collapse
|
17
|
Karron JD, Mitchell RJ. Effects of floral display size on male and female reproductive success in Mimulus ringens. ANNALS OF BOTANY 2012; 109:563-70. [PMID: 21880660 PMCID: PMC3278290 DOI: 10.1093/aob/mcr193] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS 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 pollen export per flower. To better understand how floral display size influences male and female fitness, we manipulated display phenotypes and then used paternity analysis to quantify siring success and selfing rates. METHODS To facilitate unambiguous assignment of paternity, we established four replicate (cloned) arrays of Mimulus ringens, each consisting of genets with unique combinations of homozygous marker genotypes. In each array, we trimmed displays to two, four, eight or 16 flowers. When fruits ripened, we counted the number of seeds per fruit and assigned paternity to 1935 progeny. KEY RESULTS Siring success per flower declined sharply with increasing display size, while female success per flower did not vary with display. The rate of self-fertilization increased for large floral displays, but siring losses due to geitonogamous pollen discounting were much greater than siring gains through increased self-fertilization. As display size increased, each additional seed sired through geitonogamous self-pollination was associated with a loss of 9·7 seeds sired through outcrossing. CONCLUSIONS Although total fitness increased with floral display size, the marginal return on each additional flower declined steadily as display size increased. Therefore, a plant could maximize fitness by producing small displays over a long flowering period, rather than large displays over a brief flowering period.
Collapse
Affiliation(s)
- Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
| | | |
Collapse
|
18
|
Karron JD, Ivey CT, Mitchell RJ, Whitehead MR, Peakall R, Case AL. New perspectives on the evolution of plant mating systems. ANNALS OF BOTANY 2012; 109:493-503. [PMID: 22210849 PMCID: PMC3278297 DOI: 10.1093/aob/mcr319] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
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 dramatically within and among populations. Important new insights concerning the evolutionary dynamics of plant mating systems have built upon a strong foundation of theoretical models and innovative field and laboratory experiments. However, as the pace of advancement in this field has accelerated, it has become increasingly difficult for researchers to follow developments outside their primary area of research expertise. SCOPE In this Viewpoint paper we highlight three important themes that span and integrate different subdisciplines: the changes in morphology, phenology, and physiology that accompany the transition to selfing; the evolutionary consequences of pollen pool diversity in flowering plants; and the evolutionary dynamics of sexual polymorphisms. We also highlight recent developments in molecular techniques that will facilitate more efficient and cost-effective study of mating patterns in large natural populations, research on the dynamics of pollen transport, and investigations on the genetic basis of sexual polymorphisms. This Viewpoint also serves as the introduction to a Special Issue on the Evolution of Plant Mating Systems. The 15 papers in this special issue provide inspiring examples of recent discoveries, and glimpses of exciting developments yet to come.
Collapse
Affiliation(s)
- Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
| | | | | | | | | | | |
Collapse
|
19
|
Lankinen Å, Madjidian JA. Enhancing pollen competition by delaying stigma receptivity: pollen deposition schedules affect siring ability, paternal diversity, and seed production in Collinsia heterophylla (Plantaginaceae). AMERICAN JOURNAL OF BOTANY 2011; 98:1191-200. [PMID: 21730339 DOI: 10.3732/ajb.1000510] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
PREMISE OF THE STUDY Even though pollen deposition schedules may have profound effects on the evolutionary outcome of pollen competition, few studies have investigated such effects in relation to pistil traits such as delayed stigma receptivity that enhance pollen competition. In Collinsia heterophylla, a largely outcrossing species with delayed stigma receptivity, we performed a series of controlled crosses involving several donors to understand how timing of pollen deposition influences siring ability, paternal diversity, and offspring fitness. METHODS Pollen was applied to fully receptive stigmas either as mixtures or consecutively with or without a time lag to mimic cases with early or delayed stigma receptivity. We used a genetic marker to assess offspring paternity. KEY RESULTS As expected, siring ability was affected by application order in crosses without a time lag, providing a first-donor advantage for pollen arriving on unreceptive stigmas. However, because pollen donor identity influenced siring ability, delaying stigma receptivity may still favor pollen of high competitive ability. In crosses on fully receptive pistils with a time lag of 24 h, a surprisingly high proportion of seeds (12-47%) were sired by pollen applied last. A novel finding was that pollen applied only once (as a mixture), mimicking delayed stigma receptivity, led to higher paternal diversity within progeny families, which was associated with increased seed production. CONCLUSIONS Our results suggest fitness advantages of enhancing pollen competition by delaying stigma receptivity in C. heterophylla, particularly in relation to increased paternal diversity.
Collapse
Affiliation(s)
- Åsa Lankinen
- Biodiversity, Department of Biology, Lund University, Ecology Building, 223 62 Lund, Sweden.
| | | |
Collapse
|
20
|
Flanagan RJ, Mitchell RJ, Karron JD. Effects of multiple competitors for pollination on bumblebee foraging patterns and Mimulus ringens reproductive success. OIKOS 2010. [DOI: 10.1111/j.1600-0706.2010.18777.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
21
|
Flanagan RJ, Mitchell RJ, Karron JD. Increased relative abundance of an invasive competitor for pollination, Lythrum salicaria, reduces seed number in Mimulus ringens. Oecologia 2010; 164:445-54. [PMID: 20585807 DOI: 10.1007/s00442-010-1693-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 06/08/2010] [Indexed: 11/25/2022]
Abstract
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 may be an important determinant of their effects on the pollination and reproductive success of co-occurring native species. Our study experimentally tests whether the presence and abundance of an invasive exotic, Lythrum salicaria L. (Lythraceae), influences reproductive success of a co-flowering native species, Mimulus ringens L. (Phrymaceae). We also examine the mechanisms of competition for pollination and how they may be altered by changes in competitor abundance. We found that the presence of Lythrum salicaria lowered mean seed number in Mimulus ringens fruits. This effect was most pronounced when the invasive competitor was highly abundant, decreasing the number of seeds per fruit by 40% in 2006 and 33% in 2007. Reductions in the number of seeds per fruit were likely due to reduced visit quality resulting from Mimulus pollen loss when bees foraged on neighboring Lythrum plants. This study suggests that visit quality to natives may be influenced by the presence and abundance of invasive flowering plants.
Collapse
Affiliation(s)
- Rebecca J Flanagan
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
| | | | | |
Collapse
|
22
|
Burkhardt A, Internicola A, Bernasconi G. Effects of pollination timing on seed paternity and seed mass in Silene latifolia (Caryophyllaceae). ANNALS OF BOTANY 2009; 104:767-73. [PMID: 19567418 PMCID: PMC2729624 DOI: 10.1093/aob/mcp154] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS Competition among genetically different pollen donors within one recipient flower may play an important role in plant populations, increasing offspring genetic diversity and vigour. However, under field conditions stochastic pollen arrival times may result in disproportionate fertilization success of the first-arriving pollen, even to the detriment of the recipient plant's and offspring fitness. It is therefore critical to evaluate the relative importance of arrival times of pollen from different donors in determining siring success. METHODS Hand pollinations and genetic markers were used to investigate experimentally the effect of pollination timing on seed paternity, seed mass and stigmatic wilting in the the dioecious plant Silene latifolia. In this species, high prevalence of multiply-sired fruits in natural populations suggests that competition among different donors may often take place (at fertilization or during seed development); however, the role of variation due to pollen arrival times is not known. KEY RESULTS First-arriving pollen sired significantly more seeds than later-arriving pollen. This advantage was expressed already before the first pollen tubes could reach the ovary. Simultaneously with pollen tube growth, the stigmatic papillae wilted visibly. Individual seeds were heavier in fruits where one donor sired most seeds than in fruits where both donors had more even paternity shares. CONCLUSIONS In field populations of S. latifolia, fruits are often multiply-sired. Because later-arriving pollen had decreased chances of fertilizing the ovules, this implies that open-pollinated flowers often benefit from pollen carry-over or pollinator visits within short time intervals, which may contribute to increase offspring genetic diversity and fitness.
Collapse
|
23
|
Brunet J, Holmquist KGA. The influence of distinct pollinators on female and male reproductive success in the Rocky Mountain columbine. Mol Ecol 2009; 18:3745-58. [PMID: 19674307 DOI: 10.1111/j.1365-294x.2009.04304.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although there are many reasons to expect distinct pollinator types to differentially affect a plant's reproductive success, few studies have directly examined this question. Here, we contrast the impact of two kinds of pollinators on reproductive success via male and female functions in the Rocky Mountain columbine, Aquilegia coerulea. We set up pollinator exclusion treatments in each of three patches where Aquilegia plants were visited by either day pollinators (majority bumble bees), by evening pollinators (hawkmoths), or by both (control). Day pollinators collected pollen and groomed, whereas evening pollinators collected nectar but did not groom. Maternal parents, potential fathers and progeny arrays were genotyped at five microsatellite loci. We estimated female outcrossing rate and counted seeds to measure female reproductive success and used paternity analysis to determine male reproductive success. Our results document that bumble bees frequently moved pollen among patches of plants and that, unlike hawkmoths, pollen moved by bumble bees sired more outcrossed seeds when it remained within a patch as opposed to moving between patches. Pollinator type differentially affected the outcrossing rate but not seed set, the number of outcrossed seeds or overall male reproductive success. Multiple visits to a plant and more frequent visits by bumble bees could help to explain the lack of impact of pollinator type on overall reproductive success. The increase in selfing rate with hawkmoths likely resulted from the abundant pollen available in experimental flowers. Our findings highlighted a new type of pollinator interactions that can benefit a plant species.
Collapse
Affiliation(s)
- Johanne Brunet
- USDA-ARS, VCRU, Department of Horticulture, University of Wisconsin, Madison, WI 53706, USA.
| | | |
Collapse
|
24
|
Karron JD, Holmquist KG, Flanagan RJ, Mitchell RJ. Pollinator visitation patterns strongly influence among-flower variation in selfing rate. ANNALS OF BOTANY 2009; 103:1379-83. [PMID: 19218584 PMCID: PMC2701766 DOI: 10.1093/aob/mcp030] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS 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 substantial outcross pollen. However, since pollen carryover in this species is limited, receipt of self pollen should increase rapidly for later flowers. Here the first direct experimental test of this hypothesis is described. METHODS In order to link floral visitation sequences with selfing rates of individual flowers, replicate linear arrays were established, each composed of plants with unique genetic markers. This facilitated unambiguous assignment of paternity to all sampled progeny. A single wild bumble-bee was permitted to forage on each linear array, recording the order of floral visits on each display. Once fruits had matured, 120 fruits were harvested (four flowers from each of five floral displays in each of six arrays). Twenty-five seedlings from each fruit were genotyped and paternity was unambiguously assigned to all 3000 genotyped progeny. KEY RESULTS The order of pollinator probes on Mimulus floral displays strongly and significantly influenced selfing rates of individual fruits. Mean selfing rates increased from 21 % for initial probes to 78 % for the fourth flower probed on each display. CONCLUSIONS Striking among-flower differences in selfing rate result from increased deposition of geitonogamous (among-flower, within-display) self pollen as bumble-bees probe consecutive flowers on each floral display. The resulting heterogeneity in the genetic composition of sibships may influence seedling competition and the expression of inbreeding depression.
Collapse
Affiliation(s)
- Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, 53201, USA.
| | | | | | | |
Collapse
|
25
|
Flanagan RJ, Mitchell RJ, Knutowski D, Karron JD. Interspecific pollinator movements reduce pollen deposition and seed production in Mimulus ringens (Phrymaceae). AMERICAN JOURNAL OF BOTANY 2009; 96:809-815. [PMID: 21628236 DOI: 10.3732/ajb.0800317] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
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 reproductive success of Mimulus ringens, a wetland plant native to eastern North America. Pollinator flights between these species significantly reduced the amount of conspecific pollen deposited on Mimulus stigmas and the number of seeds in Mimulus fruits, suggesting that pollen loss is an important mechanism of competition for pollination. Although pollen loss is often attributed to pollen wastage on heterospecific floral structures, our novel findings suggest that grooming by bees as they forage on a competitor may also significantly reduce outcross pollen export and seed set in Mimulus ringens.
Collapse
Affiliation(s)
- Rebecca J Flanagan
- Department of Biological Sciences, P.O. Box 413, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 USA
| | | | | | | |
Collapse
|
26
|
Fishman L, Aagaard J, Tuthill JC. TOWARD THE EVOLUTIONARY GENOMICS OF GAMETOPHYTIC DIVERGENCE: PATTERNS OF TRANSMISSION RATIO DISTORTION IN MONKEYFLOWER (MIMULUS) HYBRIDS REVEAL A COMPLEX GENETIC BASIS FOR CONSPECIFIC POLLEN PRECEDENCE. Evolution 2008; 62:2958-70. [DOI: 10.1111/j.1558-5646.2008.00475.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
27
|
Teixeira S, Foerster K, Bernasconi G. Evidence for inbreeding depression and post-pollination selection against inbreeding in the dioecious plant Silene latifolia. Heredity (Edinb) 2008; 102:101-12. [PMID: 18698334 DOI: 10.1038/hdy.2008.86] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In many species, inbred individuals have reduced fitness. In plants with limited pollen and seed dispersal, post-pollination selection may reduce biparental inbreeding, but knowledge on the prevalence and importance of pollen competition or post-pollination selection after non-self pollination is scarce. We tested whether post-pollination selection favours less related pollen donors and reduces inbreeding in the dioecious plant Silene latifolia. We crossed 20 plants with pollen from a sibling and an unrelated male, and with a mix of both. We found significant inbreeding depression on vegetative growth, age at first flowering and total fitness (22% in males and 14% in females). In mixed pollinations, the unrelated male sired on average 57% of the offspring. The greater the paternity share of the unrelated sire, the larger the difference in relatedness of the two males to the female. The effect of genetic similarity on paternity is consistent with predictions for post-pollination selection, although paternity, at least in some crosses, may be affected by additional factors. Our data show that in plant systems with inbreeding depression, such as S. latifolia, pollen or embryo selection after multiple-donor pollination may indeed reduce inbreeding.
Collapse
Affiliation(s)
- S Teixeira
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | | | | |
Collapse
|
28
|
Teixeira S, Bernasconi G. High prevalence of multiple paternity within fruits in natural populations ofSilene latifolia, as revealed by microsatellite DNA analysis. Mol Ecol 2007; 16:4370-9. [PMID: 17784922 DOI: 10.1111/j.1365-294x.2007.03493.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Data on multiple paternity within broods has been gathered in several animal species, and comparable data in plants would be of great importance to understand the evolution of reproductive traits in a common framework. In this study, we first isolated and characterized six microsatellite loci from the dioecious plant Silene latifolia (Caryophyllaceae). The polymorphism of the loci was assessed in 60 individual females from four different populations. Two of the investigated loci showed a pattern of inheritance consistent with X-linkage. These microsatellite loci were highly polymorphic and therefore useful tools for parentage analysis. We then used four of the markers to determine paternity within naturally pollinated fruits in four European populations. This study revealed widespread multiple paternity in all populations investigated. The minimum number of fathers per fruit varied from one to nine, with population means ranging from 3.4 to 4.9. The number of fathers per fruit was not significantly correlated with offspring sex ratios. High prevalence of multiple paternity within fruits strongly suggest that pollen competition is likely to occur in this species. This may substantially impact male reproductive success and possibly contribute to increase female and offspring fitness, either through postpollination selection or increased genetic diversity. Wide variation in outcrossing rates may be an overlooked aspect of plant mating systems.
Collapse
Affiliation(s)
- Sara Teixeira
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | | |
Collapse
|
29
|
Marshall DL, Reynolds J, Abrahamson NJ, Simpson HL, Barnes MG, Medeiros JS, Walsh S, Oliveras DM, Avritt JJ. Do differences in plant and flower age change mating patterns and alter offspring fitness in Raphanus sativus (Brassicaceae)? AMERICAN JOURNAL OF BOTANY 2007; 94:409-18. [PMID: 21636410 DOI: 10.3732/ajb.94.3.409] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
When more pollen is present on stigmas than needed to fertilize all ovules, selection among pollen grains may occur due to effects of both pollen donors and maternal plants. We asked whether increasing plant age and flower age, two changes in maternal condition, altered the pattern of seed paternity after mixed pollination. We also asked whether changes in seed paternity affected offspring success in an experimental garden. While flower age did not affect seed paternity, there was a dramatic shift in pollen donor performance as plants aged. These differences were seen in the offspring as well, where the offspring of one pollen donor, which sired more seeds on young plants, flowered earlier in the season, and the offspring of another pollen donor, which sired more seeds on old plants, flowered later in the season. Thus, change in maternal condition resulted in altered seed paternity, perhaps because the environment for pollen tube growth was different. The pattern of seed paternity and offspring performance suggests that pollen donors may show temporal specialization.
Collapse
Affiliation(s)
- Diane L Marshall
- Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131 USA
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Karron JD, Mitchell RJ, Bell JM. Multiple pollinator visits to Mimulus ringens (Phrymaceae) flowers increase mate number and seed set within fruits. AMERICAN JOURNAL OF BOTANY 2006; 93:1306-12. [PMID: 21642195 DOI: 10.3732/ajb.93.9.1306] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
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 probes is brief. When pollen carryover is limited, sequential pollen loads may also differ markedly in sire representation. We hypothesized that these conditions help explain high levels of multiple paternity in Mimulus ringens fruits. We documented all bee visits to individual flowers, quantified resulting seed set, and determined paternity for 20 seeds per fruit. Most (76%) flowers received multiple probes, and the interval between probes was usually <30 min. Flowers probed multiple times produced 44% more seeds than flowers probed once. All fruits were multiply sired. Flowers receiving a single probe averaged 3.12 outcross sires per fruit, indicating that single probes deposit pollen from several donors. Multiple paternity was even greater after three or more probes (4.92 outcross sires), demonstrating that sequential visits bring pollen from donors not represented in the initial probe.
Collapse
Affiliation(s)
- Jeffrey D Karron
- Department of Biological Sciences, P. O. Box 413, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 USA
| | | | | |
Collapse
|
31
|
Jordan CY, Harder LD. Manipulation of Bee Behavior by Inflorescence Architecture and Its Consequences for Plant Mating. Am Nat 2006; 167:496-509. [PMID: 16670993 DOI: 10.1086/501142] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Accepted: 11/07/2005] [Indexed: 11/03/2022]
Abstract
Angiosperms display flowers in many three-dimensional arrangements, but the functional significance of this diversity is largely unknown. We examined influences of inflorescence architecture on pollination and mating by quantifying the responses of bumblebees to three architectures and then using these observations as the basis of a model that simulated pollen dispersal. On artificial panicles, racemes, and umbels, each with 12 identical flowers, bees visited one more flower, on average, on umbels than on panicles (with racemes being intermediate). In contrast to this weak response, the consistency of foraging paths among flowers differed strongly among architectures (raceme > panicle > umbel). The simulation model revealed limited differences in self-pollination and pollen export among the three inflorescence designs when all flowers presented and received pollen, because mating differences depended on only the number of flowers visited. In contrast, in simulations of inflorescences on which pollen receipt and presentation were segregated so as to minimize interference among flowers, the consistency of movement paths governed mating. In this case, racemes self-pollinated much less than umbels (with panicles being intermediate), and racemes exported much more pollen than umbels and panicles. These effects have diverse consequences for the evolution of inflorescence architecture, flower design, and sexual segregation.
Collapse
Affiliation(s)
- Crispin Y Jordan
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
| | | |
Collapse
|