TY - JOUR
T1 - Absence of native flower visitors for the endangered Hawaiian mint Stenogyne angustifolia
T2 - Impending ecological extinction?
AU - Aslan, Clare E.
AU - Liang, Christina T.
AU - Shiels, Aaron B.
AU - Haines, William
N1 - Funding Information:
We extend our deep appreciation to H. Coad, M. Donofrio, J. Felt, J. Smith, and A. Wagner for many hours of field support. We thank everyone at the PTA Natural Resources Office for their logistical support and assistance. This work was performed under USFWS Native Endangered Species Recovery Permit: TE-28360B-0; Hawaii DLNR-DOFAW Permit for Threatened & Endangered Plant Species: P-201; and Hawaii DLNR-DOFAW Permit for Native Invertebrate Research: FHM17-428. Funding for this research was provided by the Department of Defense Strategic Environmental Research and Development Program [grant number RC-2432 ]. We are deeply grateful to R. Paull for laboratory analysis assistance and to K. Magnacca for bee identification assistance. We thank D. Drake for invaluable comments on an earlier draft of this manuscript.
Publisher Copyright:
© 2018 The Authors
PY - 2018/10
Y1 - 2018/10
N2 - If an organism becomes rare enough that it no longer participates in certain interspecific interactions, it can be said to have become ecologically extinct, even though it is still present. This form of extinction is much less recognized than global extinctions, although it may have ramifications for ecological community function. Here, we describe a case of possible or pending ecological extinction of an endemic Hawaiian plant. We performed over 120 h of systematic flower visitation observations of the endangered Hawaiian mint, Stenogyne angustifolia, in its wild habitat. The robust size and open shape of S. angustifolia flowers, along with their high accessibility, visibility, and nectar content, suggest that they are adapted to animal-mediated pollination. However, only one flower visitor was observed at our focal high-elevation study site: an individual of the non-native bee species Lasioglossum impavidum. Experimental pollination treatments indicate that S. angustifolia is self-compatible and demonstrates some autogamy, setting fruit and seed in the absence of pollinators. However, experimental additions of pollen increased fruit production, indicating that plants are pollen-limited and that lack of pollinators carries a reproductive cost for this species. Ecological communities throughout Hawaii are highly modified, and the distribution and diversity of the native pollinator community that occurred with S. angustifolia prior to these changes are wholly unknown. Nevertheless, the lack of visitation by native pollinators and extremely rare visitation by non-native pollinators suggest that this plant is today contributing little to pollination networks in its high-elevation habitat.
AB - If an organism becomes rare enough that it no longer participates in certain interspecific interactions, it can be said to have become ecologically extinct, even though it is still present. This form of extinction is much less recognized than global extinctions, although it may have ramifications for ecological community function. Here, we describe a case of possible or pending ecological extinction of an endemic Hawaiian plant. We performed over 120 h of systematic flower visitation observations of the endangered Hawaiian mint, Stenogyne angustifolia, in its wild habitat. The robust size and open shape of S. angustifolia flowers, along with their high accessibility, visibility, and nectar content, suggest that they are adapted to animal-mediated pollination. However, only one flower visitor was observed at our focal high-elevation study site: an individual of the non-native bee species Lasioglossum impavidum. Experimental pollination treatments indicate that S. angustifolia is self-compatible and demonstrates some autogamy, setting fruit and seed in the absence of pollinators. However, experimental additions of pollen increased fruit production, indicating that plants are pollen-limited and that lack of pollinators carries a reproductive cost for this species. Ecological communities throughout Hawaii are highly modified, and the distribution and diversity of the native pollinator community that occurred with S. angustifolia prior to these changes are wholly unknown. Nevertheless, the lack of visitation by native pollinators and extremely rare visitation by non-native pollinators suggest that this plant is today contributing little to pollination networks in its high-elevation habitat.
KW - Creeping mint
KW - Flower pollination treatments
KW - Flower visitation observations
KW - Island endemic
KW - Lasioglossum
KW - Mutualism disruption
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U2 - 10.1016/j.gecco.2018.e00468
DO - 10.1016/j.gecco.2018.e00468
M3 - Article
AN - SCOPUS:85056209665
SN - 2351-9894
VL - 16
JO - Global Ecology and Conservation
JF - Global Ecology and Conservation
M1 - e00468
ER -