Abstract
Echinopsis chiloensis is an endemic cactus from Chile, distributed in a temperature and rainfall gradient between 30° and 35° South latitude, with mean temperatures increasing and precipitation decreasing toward the north. It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals. In this study, we investigated the consequences of parasitism over the fitness and physiology of this cactus throughout its distribution range and how it is affected by the environment. We measured five functional traits in eight populations latitudinally distributed, the first three only for the host: reproductive fitness, stomatal traits (density and size), and photosynthesis (during winter and summer); and the last two for the host and parasite: stable isotopes (∂ 13 C and ∂ 15 N), and nutrients (carbon and nitrogen content). The results showed a negative effect of parasitism over fitness of infected cacti. However, the higher nitrogen concentrations in cactus tissues toward the south improved overall fitness. Regarding photosynthesis, we only observed a negative effect of parasitism during the dry season (summer), which is also negatively affected by the increase in summer temperatures and decrease in winter rainfall toward the north. There were no differences in nutrient concentration or in the isotopic signature of healthy and infected cacti. Conversely, we observed a higher carbon and lower nitrogen concentration in mistletoes than in cacti regardless of latitude. The loss of temperature seasonality toward the north increases the C:N ratio, and the values between the parasite and its host diverge. ∂ 15 N was similar between parasites and hosts while ∂ 13 C of the parasite was enriched when compared to its host. Overall, the infection by T. aphyllus affects Echinopsis chiloensis fitness but showed no strong effects over the cactus physiology, except for the summer photosynthesis. Therefore, our data revealed that E. chiloensis response to T. aphyllus infection is sensitive to environmental changes in a way that could be strongly impacted by the desertification projected for this area due to climate change.
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Claims 13
Claim · model-written summary
Parasitism reduced infected cactus reproductive fitness.
- Taxon
- Echinopsis chiloensis
Leucostele chiloensise1 - Interactor
- Tristerix aphyllus
Tristerix aphylluse2parasite - Outcome
- fitness of infected cactie0
- Direction
- negative effecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The results showed a negative effect of parasitism over fitness of infected cacti.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”
Claim · model-written summary
Higher cactus tissue nitrogen toward the south improved overall fitness.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Compound
- nitrogene0
- Outcome
- overall fitnesse0
- Direction
- improvede0
- Setting
- toward the southe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, the higher nitrogen concentrations in cactus tissues toward the south improved overall fitness.”
e1“Echinopsis chiloensis is an endemic cactus”
Claim · model-written summary
Parasitism reduced cactus photosynthesis during summer.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Interactor
- Tristerix aphyllusTristerix aphylluse2parasite
- Outcome
- photosynthesise0
- Direction
- negative effecte0
- Qualifier
- dry season (summer)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding photosynthesis, we only observed a negative effect of parasitism during the dry season (summer), which is also negatively affected by the increase in summer temperatures and decrease in winter rainfall toward the north.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”
Claim · model-written summary
Northward summer warming was associated with lower cactus photosynthesis.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Outcome
- photosynthesise0
- Direction
- negatively affectede0
- Qualifier
- increase in summer temperaturese0
- Setting
- toward the northe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding photosynthesis, we only observed a negative effect of parasitism during the dry season (summer), which is also negatively affected by the increase in summer temperatures and decrease in winter rainfall toward the north.”
e1“Echinopsis chiloensis is an endemic cactus”
Claim · model-written summary
Northward decline in winter rainfall was associated with lower cactus photosynthesis.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Outcome
- photosynthesise0
- Direction
- negatively affectede0
- Qualifier
- decrease in winter rainfalle0
- Setting
- toward the northe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding photosynthesis, we only observed a negative effect of parasitism during the dry season (summer), which is also negatively affected by the increase in summer temperatures and decrease in winter rainfall toward the north.”
e1“Echinopsis chiloensis is an endemic cactus”
Claim · model-written summary
Healthy and infected cacti had no nutrient concentration differences.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Outcome
- nutrient concentratione0
- Direction
- no differencese0
- Comparator
- healthy and infected cactie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no differences in nutrient concentration or in the isotopic signature of healthy and infected cacti.”
e1“Echinopsis chiloensis is an endemic cactus”
Claim · model-written summary
Healthy and infected cacti had no isotopic signature differences.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Outcome
- isotopic signaturee0
- Direction
- no differencese0
- Comparator
- healthy and infected cactie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no differences in nutrient concentration or in the isotopic signature of healthy and infected cacti.”
e1“Echinopsis chiloensis is an endemic cactus”
Claim · model-written summary
Mistletoes had higher carbon concentration than cacti regardless of latitude.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Interactor
- Tristerix aphyllusTristerix aphylluse2parasite
- Outcome
- carbone0
- Direction
- highere0
- Comparator
- cactie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Conversely, we observed a higher carbon and lower nitrogen concentration in mistletoes than in cacti regardless of latitude.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”
Claim · model-written summary
Mistletoes had lower nitrogen concentration than cacti regardless of latitude.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Interactor
- Tristerix aphyllusTristerix aphylluse2parasite
- Outcome
- nitrogen concentration in mistletoese0
- Direction
- lowere0
- Comparator
- cactie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Conversely, we observed a higher carbon and lower nitrogen concentration in mistletoes than in cacti regardless of latitude.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”
Claim · model-written summary
Loss of temperature seasonality northward increased the C:N ratio.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Outcome
- C:N ratioe0
- Direction
- increasese0
- Qualifier
- loss of temperature seasonalitye0
- Setting
- toward the northe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The loss of temperature seasonality toward the north increases the C:N ratio, and the values between the parasite and its host diverge.”
e1“Echinopsis chiloensis is an endemic cactus”
Claim · model-written summary
C:N ratios of parasite and host diverged northward.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Interactor
- Tristerix aphyllusTristerix aphylluse2parasite
- Outcome
- values between the parasite and its hoste0
- Direction
- divergee0
- Setting
- toward the northe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The loss of temperature seasonality toward the north increases the C:N ratio, and the values between the parasite and its host diverge.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”
Claim · model-written summary
Parasites and hosts had similar ∂ 15 N.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Interactor
- Tristerix aphyllusTristerix aphylluse2parasite
- Outcome
- ∂ 15 Ne0
- Direction
- similare0
- Comparator
- parasites and hostse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“∂ 15 N was similar between parasites and hosts while ∂ 13 C of the parasite was enriched when compared to its host.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”
Claim · model-written summary
Parasite ∂ 13 C was enriched relative to host.
- Taxon
- Echinopsis chiloensisLeucostele chiloensise1
- Interactor
- Tristerix aphyllusTristerix aphylluse2parasite
- Outcome
- ∂ 13 C of the parasitee0
- Direction
- enrichede0
- Comparator
- its hoste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“∂ 15 N was similar between parasites and hosts while ∂ 13 C of the parasite was enriched when compared to its host.”
e1“Echinopsis chiloensis is an endemic cactus”
e2“It is the main host of the mistletoe Tristerix aphyllus , a holoparasite completely dependent on the cactus for water, carbon, and minerals.”