Abstract
This is the first study in cycads to measure genetics, demography, and survival of plant populations due to an invasive insect. The armored scale Aulacaspis yasumatsui invaded the island of Rota in 2007 posing a new threat to the native Cycas micronesica population. The pre-invasion genetic structure of the host plant populations revealed considerable genetic variation and restricted gene flow among habitats and identified genetic clusters representing the genetic variation of the species in Rota. Prior to localized A. yasumatsui infestations, 28 permanent plots were established among seven locations in 2008. Data were collected to document survival and demography until 2023. There were 11,254 stems per ha in 2008, 9.2% of which were adult trees. The seedlings rapidly reached 100% mortality, and no seedlings were observed in the plots from 2014 until 2023. There were 149 stems per ha in 2023, 100% of which were adult trees. This invasion behaved similarly to the invasions of other islands, with the native cycad population reaching 98.6% mortality of the entire population and 85.6% mortality of the adult tree population within a 15-year span. Mean stem height was only 30 cm in 2008 because of the majority of the population was seedlings and juveniles. Mean stem height gradually increased with each successive year of data collection due to selective mortality of the small plants, and was 245 cm in 2023. Mean leaf number per adult tree was 83 in 2008, abruptly declined to a low of 8 in 2013, then gradually increased to 20 in 2023. Incidence of the herbivore rapidly increased to a peak in 2011 before stabilizing to about 40% to 50% of the soft organ surfaces. The invasion of this insular cycad population by A. yasumatsui caused selective mortality of the smallest plants, and the population-level mortality was more rapid than the prior invasion of nearby Guam. These combined results provide a genetic baseline and population structure benchmark for future conservation protocols during species recovery efforts. The geographically separated and genetically isolated populations indicate this cycad species remains highly vulnerable to localized extirpations, as the unique alleles from extirpated habitats are at risk of being lost forever.
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Claims 20
Claim · model-written summary
The pre-invasion Cycas micronesica populations on Rota showed considerable genetic variation.
- Taxon
- Cycas micronesica
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Cycas micronesicat0 - Outcome
- considerable genetic variatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
t0“Cycas micronesica”
e0“The pre-invasion genetic structure of the host plant populations revealed considerable genetic variation and restricted gene flow among habitats and identified genetic clusters”
Claim · model-written summary
The pre-invasion Cycas micronesica populations showed restricted gene flow among habitats.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- restricted gene flowe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“The pre-invasion genetic structure of the host plant populations revealed considerable genetic variation and restricted gene flow among habitats and identified genetic clusters”
Claim · model-written summary
Genetic clusters representing the genetic variation of the species on Rota were identified in the pre-invasion populations.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- genetic clusterse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“The pre-invasion genetic structure of the host plant populations revealed considerable genetic variation and restricted gene flow among habitats and identified genetic clusters”
Claim · model-written summary
There were 11,254 stems per ha in 2008.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- stems per hae0
- Value
- 11,254e0
- Qualifier
- 2008e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“There were 11,254 stems per ha in 2008, 9.2% of which were adult trees”
Claim · model-written summary
9.2% of the stems in 2008 were adult trees.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- adult treese0
- Value
- 9.2%e0
- Qualifier
- 2008e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“There were 11,254 stems per ha in 2008, 9.2% of which were adult trees”
Claim · model-written summary
Seedlings rapidly reached 100% mortality.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Organ / stage
- seedlingse0
- Outcome
- mortalitye0
- Value
- 100%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“The seedlings rapidly reached 100% mortality”
Claim · model-written summary
There were 149 stems per ha in 2023.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- stems per hae0
- Value
- 149e0
- Qualifier
- 2023e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“There were 149 stems per ha in 2023, 100% of which were adult trees”
Claim · model-written summary
All stems (100%) in 2023 were adult trees.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- adult treese0
- Value
- 100%e0
- Qualifier
- 2023e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“There were 149 stems per ha in 2023, 100% of which were adult trees”
Claim · model-written summary
The native cycad population reached 98.6% mortality of the entire population within a 15-year span.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- mortality of the entire populatione0
- Value
- 98.6%e0
- Qualifier
- within a 15-year spane0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“the native cycad population reaching 98.6% mortality of the entire population and 85.6% mortality of the adult tree population within a 15-year span”
Claim · model-written summary
The adult tree population reached 85.6% mortality within a 15-year span.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- mortality of the adult tree populatione0
- Value
- 85.6%e0
- Qualifier
- within a 15-year spane0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“the native cycad population reaching 98.6% mortality of the entire population and 85.6% mortality of the adult tree population within a 15-year span”
Claim · model-written summary
Mean stem height was 30 cm in 2008.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- Mean stem heighte0
- Value
- 30 cme0
- Qualifier
- 2008e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Mean stem height was only 30 cm in 2008”
Claim · model-written summary
Mean stem height gradually increased each year, reaching 245 cm in 2023, attributed to selective mortality of the small plants.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- Mean stem heighte0
- Direction
- gradually increasede0
- Value
- 245 cme0
- Qualifier
- selective mortality of the small plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Mean stem height gradually increased with each successive year of data collection due to selective mortality of the small plants, and was 245 cm in 2023”
Claim · model-written summary
Mean leaf number per adult tree was 83 in 2008.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- Mean leaf number per adult treee0
- Value
- 83e0
- Qualifier
- 2008e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Mean leaf number per adult tree was 83 in 2008, abruptly declined to a low of 8 in 2013, then gradually increased to 20 in 2023”
Claim · model-written summary
Mean leaf number per adult tree abruptly declined to a low of 8 in 2013.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- Mean leaf number per adult treee0
- Direction
- abruptly declinede0
- Value
- 8e0
- Qualifier
- 2013e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Mean leaf number per adult tree was 83 in 2008, abruptly declined to a low of 8 in 2013, then gradually increased to 20 in 2023”
Claim · model-written summary
Mean leaf number per adult tree then gradually increased to 20 in 2023.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- Mean leaf number per adult treee0
- Direction
- gradually increasede0
- Value
- 20e0
- Qualifier
- 2023e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Mean leaf number per adult tree was 83 in 2008, abruptly declined to a low of 8 in 2013, then gradually increased to 20 in 2023”
Claim · model-written summary
Incidence of the herbivore rapidly increased to a peak in 2011.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Interactor
- herbivoree0herbivore
- Outcome
- Incidence of the herbivoree0
- Direction
- rapidly increasede0
- Qualifier
- peak in 2011e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Incidence of the herbivore rapidly increased to a peak in 2011 before stabilizing to about 40% to 50% of the soft organ surfaces”
Claim · model-written summary
Herbivore incidence then stabilized at about 40% to 50% of the soft organ surfaces.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Interactor
- herbivoree0herbivore
- Outcome
- Incidence of the herbivoree0
- Direction
- stabilizinge0
- Value
- about 40% to 50%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“Incidence of the herbivore rapidly increased to a peak in 2011 before stabilizing to about 40% to 50% of the soft organ surfaces”
Claim · model-written summary
Invasion by A. yasumatsui caused selective mortality of the smallest plants in the insular cycad population.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Interactor
- A. yasumatsui
Aulacaspis yasumatsuie0pest - Outcome
- selective mortality of the smallest plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“The invasion of this insular cycad population by A. yasumatsui caused selective mortality of the smallest plants”
Claim · model-written summary
Population-level mortality of the Rota cycad was more rapid than in the prior invasion of nearby Guam.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- population-level mortalitye0
- Direction
- more rapide0
- Comparator
- prior invasion of nearby Guame0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“the population-level mortality was more rapid than the prior invasion of nearby Guam”
Claim · model-written summary
The authors conclude that the geographically separated and genetically isolated populations remain highly vulnerable to localized extirpations.
- Taxon
- Cycas micronesicaCycas micronesicat0
- Outcome
- highly vulnerable to localized extirpationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Cycas micronesica”
e0“The geographically separated and genetically isolated populations indicate this cycad species remains highly vulnerable to localized extirpations”