| 1. |
- Hersh, Evan, et al.
(author)
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Sexual antagonism in the pistil varies among populations of a hermaphroditic mixed-mating plant.
- 2015
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In: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 28:7, s. 1321-1334
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Journal article (peer-reviewed)abstract
- Sexual conflicts and their evolutionary outcomes may be influenced by population-specific features such as mating system and ecological context; however, very few studies have investigated the link between sexual conflict and mating system. The self-compatible, mixed-mating hermaphrodite Collinsia heterophylla (Plantaginaceae) is thought to exhibit a sexual conflict over timing of stigma receptivity. This conflict involves 1) delayed stigma receptivity, which intensifies pollen competition, and 2) early fertilization forced by pollen, which reduces seed set. We investigated the potential for the conflict to occur under field conditions and performed greenhouse crosses within eight populations to assess its consistency across populations. Flowers were visited, and produced seeds after pollination, at all developmental stages, suggesting that the conflict can be of significance under natural conditions. In the greenhouse, early pollination imposed costs in all populations. Overall, the timing of first seed set was most strongly affected by the maternal parent, denoting stronger female than male ability to influence onset of stigma receptivity. Crosses also revealed a negative relationship between donor- and recipient-related onset of receptivity within individuals, a novel result hinting at trade-offs in sex-allocation or a history of antagonistic selection. Neither timing of stigma receptivity, timing of first seed set, nor pollen competitive ability covaried with population outcrossing rate. In conclusion, these results indicate that sexually antagonistic selection may be present in varying degrees in different populations of C. heterophylla, but this variation does not appear to be directly related to mating system variation. This article is protected by copyright. All rights reserved.
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| 2. |
- Karlsson, Kristina, et al.
(author)
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Active males, reactive females: stereotypic sex roles in sexual conflict research?
- 2011
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In: Animal Behaviour. - : Elsevier BV. - 1095-8282 .- 0003-3472. ; 81:5, s. 901-907
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Research review (peer-reviewed)abstract
- Sexual selection research has always been a subject for debate. Much of the criticism has concerned the imposition of conventional sex roles based on an anthropomorphic view of animals imposed by the researcher. This conventional view may have hampered research, for example from acknowledging male mate choice. Sexual conflict theory is a fast-growing research field, which initially stems from sexual selection research. We investigated how the sexes are described in sexual conflict research and what characteristics they are assigned. We assessed these topics with literature studies of (1) the terminology used and (2) what parameters are incorporated in sexual conflict models. We found that males and females are consequently described with different words, which have different connotations regarding activity in the conflict. Furthermore, theoretical models mainly investigate conflict costs for females, although costs for both sexes are necessary for coevolutionary dynamics. We argue that sexual conflict research uses stereotypic characterizations of the sexes, where males are active and females reactive. Thus, previous discussions on the use of anthropomorphic terms in sexual selection seem not to have had any impact on sexual conflict research, which is why the topic of stereotyping the sexes is still of current importance. We suggest that scientific gains can be made by eliminating a sex-stereotyped perspective. (C) 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
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| 3. |
- Lankinen, Åsa, et al.
(author)
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Effect of root contact on pollen competitive ability in a hermaphroditic winter-annual herb
- 2016
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In: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 30:4, s. 739-754
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Journal article (peer-reviewed)abstract
- Presence of a root neighbor can induce changes in root allocation and pollen traits, but only a limited number of studies have investigated such effects on pollen. To learn more about effects of root contact on pollen competitive ability, we studied plants of the hermaphroditic winter-annual Collinsia heterophylla, native to California. We cultivated plants in two-pot treatments with roots kept either separate or intermingled with the same amount of resources. Pollen-tube growth rate, as an indication of pollen competitive ability, was affected by root treatment but the response varied among competing plant families. The response to root-treatment was not an effect of differential resource uptake of the two competitors. Root biomass was significantly higher when roots were intermingled compared to separate. This finding adds to the number of species with a strategic root response in the presence of competitors, but could also be a consequence of a larger rooting volume. Allocation to pollen performance versus roots in the presence of a competitor was lower in small plants and higher in large plants, potentially implying high costs of producing competitive pollen. We conclude that our study demonstrated that pollen tube growth rate is highly sensitive to the root environment in C. heterophylla.
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| 4. |
- Lankinen, Åsa, et al.
(author)
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Enhancing Pollen Competition By Delaying Stigma Receptivity: Pollen Deposition Schedules Affect Siring Ability, Paternal Diversity, And Seed Production In Collinsia Heterophylla (Plantaginaceae)
- 2011
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 98:7, s. 1191-1200
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Journal article (peer-reviewed)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.
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| 5. |
- Lankinen, Åsa, et al.
(author)
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Geographic variation in floral traits is associated with environmental and genetic differences among populations of the mixed mating species Collinsia heterophylla (Plantaginaceae)
- 2017
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In: Botany. - : Canadian Science Publishing. - 1916-2804 .- 1916-2790. ; 95:2, s. 121-128
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Journal article (peer-reviewed)abstract
- Relatively few studies have investigated how geography, environmental factors, and genetics affect floral trait variation. We used mixed-mating Collinsia heterophylla Buist to explore variation in a suite of floral traits related to mating system in populations representing four geographic regions of California, USA, and relate this variation to geography, climatic factors, and local site characteristics. We evaluated the environmental vs. genetic trait variability in the greenhouse. Stage of anther–stigma contact correlated positively with temperature, stage of stigma receptivity was negatively associated with vegetation cover, and flower size differed among populations without any clear relation to environmental factors. Greenhouse data indicated heritability for stage of anther– stigma contact, flower size, and time to flowering, and positive correlations between field and greenhouse for stage of stigma receptivity and flower size; however, stage of anther–stigma contact showed a high degree of environmental influence. Stage of anther–stigma contact covaried positively with stage of stigma receptivity and flower size across maternal families, indicating genetic correlations between traits. In conclusion, phenotypic floral variation within mixed-mating C. heterophylla is mostly determined by a genetic component. Geography, environment, and genetics affect traits differently, suggesting that ecological and evolutionary processes contribute to shaping variability in mating system-related traits.
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| 6. |
- Lankinen, Åsa, et al.
(author)
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Selection on pollen and pistil traits during pollen competition is affected by both sexual conflict and mixed mating in a self-compatible herb.
- 2016
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In: American Journal of Botany. - : Wiley. - 1537-2197 .- 0002-9122. ; 103:3, s. 541-552
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Journal article (peer-reviewed)abstract
- Although much attention has focused on the diversity of plant mating systems, only a few studies have considered the joint effects of mating system and sexual conflict in plant evolution. In mixed-mating Collinsia heterophylla, a sexual conflict over timing of stigma receptivity is proposed: pollen with a capacity to induce early onset of stigma receptivity secures paternity for early-arriving pollen (at the expense of reduced maternal seed set), whereas late onset of stigma receptivity mitigates the negative effects of early-arriving pollen. Here we investigated whether selection on pollen and pistil traits involved in sexual conflict is affected by the presence of both outcross- and self-pollen (mixed mating) during pollen competition.
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| 7. |
- Larsson, Mattias, et al.
(author)
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Floral scent and pollinator visitation in relation to floral colour morph in the mixed-mating annual herb Collinsia heterophylla
- 2021
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In: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 39:4
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Journal article (peer-reviewed)abstract
- Even though floral scent is of major importance for pollinator attraction, it is less investigated than other floral traits. Previous studies suggest the importance of joint exploration of olfactory and visual floral cues to understand plant–pollinator interactions. We investigated flower scents in Collinsia heterophylla, a bee-pollinated, annual herb a with mixed-mating system combining self- and outcross-pollination. In Collinsia, floral size and development variation is related to mating system, ranging from large-flowered mixed-mating species to small-flowered self-pollinated species. However, to our knowledge, flower scent has not been described in any species in the genus. We also studied whether flower-emitted volatiles were coupled to presence versus absence of a coloured band on the upper lip within a population in C. heterophylla, and if these colour morphs affected pollinator visitation. We performed headspace collections of volatiles in the greenhouse from potted flowering plants, and compared these to controls in the bud stage. Flower-specific volatiles were highly dominated by terpenoid compounds typical of bee-pollinated plants, such as β-myrcene, (Z)- and (E)-ocimene and sesquiterpenes (E)-α-bergamotene and β-sesquiphellandrene. The aliphatic ester methyl hexanoate was also prominent, together with additional esters, whereas methyl cinnamate constituted the only aromatic compound. Floral colour morphs showed no qualitative difference in volatiles, but the coloured morph produced significantly higher quantities for seven of the 26 individual flower compounds. A field experiment performed within a natural population, using behavioural observations and florescent dyes dusted on the flowers, could not detect any differences in pollinator visitation between colour morphs. We conclude that C. heterophylla flowers emit volatile compounds commonly associated with attraction of their most important pollinators. It would be highly interesting to explore the function of floral scent for pollinator attraction and relate floral scent to mating system variation across Collinsia for a better understanding of pollinator influence on floral evolution.
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| 8. |
- Madjidian, Josefin A., et al.
(author)
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Direct and indirect selection on mate choice during pollen competition : Effects of male and female sexual traits on offspring performance following two-donor crosses
- 2020
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In: Journal of evolutionary biology. - : Wiley. - 1010-061X .- 1420-9101. ; 33:10, s. 1452-1467
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Journal article (peer-reviewed)abstract
- Mate choice in plants is poorly understood, in particular its indirect genetic benefits, but also the direct benefits of avoiding harmful matings. In the herb Collinsia heterophylla, delayed stigma receptivity has been suggested to enhance pollen competition, potentially functioning as a female mate choice trait. Previous studies show that this trait can mitigate the cost of early fertilization caused by pollen, thus providing a direct benefit. We performed two-donor pollinations during successive floral stages to assess how this stigma receptivity trait and two pollen traits known to affect siring success influence indirect benefits in terms of offspring performance. We also investigated differential resource allocation by studying the influence of sibling performance in the same capsule. Offspring performance in terms of flower number was mainly affected by parental identities and differential resource allocation. Offspring seed production showed some influence of resource allocation, but was also affected by pollen donor identity and varied positively with late stigma receptivity. However, the effect of late stigma receptivity on offspring seed production was weakened in matings with pollen that advanced stigma receptivity. In conclusion, delayed stigma receptivity may be selected through both direct and indirect fitness effects in C. heterophylla, where pollen-based delay on stigma receptivity might act as a cue for mate choice. However, selection may also be counteracted by antagonistic selection on pollen to advance stigma receptivity. Our results highlight the challenges of studying indirect genetic benefits and other factors that influence mate choice in plants.
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