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Pollen performance decreases with plant age for outcrosser but not selfer: evidence for cost of male performance
Author(s) -
Malagon Daniel A.,
Roche Morgan D.,
McElderry Robert M.,
Kalisz Susan
Publication year - 2019
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/ajb2.1346
Subject(s) - biology , pollen , outcrossing , selfing , reproduction , longevity , mating system , plant reproduction , pollinator , pollination , mating , botany , ecology , demography , population , genetics , sociology
Premise Declines in reproductive capabilities with increasing age are common across the tree of life. However, in plants, mating system traits have rarely been tested for signs of senescence. Since reproduction is often resource limited, we might expect outcrossing and selfing taxa to allocate these resources differently, especially as a plant ages. Compared with selfers, outcrossers are expected to produce showy, rewarding flowers that attract pollinators and high‐quality pollen that can successfully compete for ovules. Yet, this resource‐intensive strategy of outcrossers may result in declines in floral allocation and pollen performance metrics, relative to selfers. Methods To explore age‐related changes in reproduction, we measured flower size and pollen germinability over the flowering period for multiple populations of an annual sister species pair, Collinsia linearis (outcrosser) and C. rattanii (selfer), in a growth chamber experiment. Results We found that flower size decreased significantly with age in both species. The outcrosser expressed a significant and dramatic (88%) decline in pollen germinability with age, while the selfer's pollen germinability decline was non‐significant and low (17%). Conclusions Our results support the idea that the higher total cost of reproduction in outcrossers can deplete available resources more rapidly than in selfers, manifesting as a decline in male performance with plant age.