Sexual and natural selection on pollen morphology in Taraxacum

© 2020 Botanical Society of America..

PREMISE: Spiny pollen has evolved independently in multiple entomophilous lineages. Sexual selection may act on exine traits that facilitate male mating success by influencing the transfer of pollen from the anther to the body of the pollinator, while natural selection acts to increase pollen survival. We postulated that relative to sexual congeners, apomictic dandelions undergo relaxed selection on traits associated with male mating success.

METHODS: We explored sexual selection on exine traits by measuring the propensity for Taraxacum spp. pollen to attach to hairs of flower-visiting bumblebees (Bombus spp.) or flies (Diptera: Syrphidae and Muscoidea) and assessed natural selection by testing whether pollen traits defend against consumption.

RESULTS: Pollen picked up by bumblebees exhibited a narrower subset of spine-spacing phenotypes, consistent with stabilizing selection. Flies picked up larger pollen from flowers than expected at random. Surveys of corbiculae (pollen basket) contents from foraging bumblebees and feces of flies showed that pollen grains consumed by both kinds of visitors are similar in spine characteristics and size to those produced by the donor. When bees visit inflorescences of apomictic T. officinale, they pick up pollen with spine-spacing phenotypes above the mean and shifted toward those of sexual T. ceratophorum.

CONCLUSIONS: We demonstrate that traits under sexual selection during pollen pickup vary among pollinators, while natural selection for pollen defense is nil in T. ceratophorum. In hybrid zones between apomictic and sexual dandelions, pollen traits place apomictic donors at a dispersal disadvantage, potentially reinforcing reproductive isolation.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:107

Enthalten in:

American journal of botany - 107(2020), 2 vom: 20. Feb., Seite 364-374

Sprache:

Englisch

Beteiligte Personen:

Lynn, Austin [VerfasserIn]
Piotter, Emelyn [VerfasserIn]
Harrison, Ellie [VerfasserIn]
Galen, Candace [VerfasserIn]

Links:

Volltext

Themen:

Asteraceae
Bombus
Dandelion
Echinate pollen
Exine
Journal Article
Muscoidea
Phenotypic selection
Pollen evolution
Pollination
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Trade-offs

Anmerkungen:

Date Completed 16.04.2020

Date Revised 16.04.2020

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1002/ajb2.1428

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM306467070