Invasive species ecology

Exploring the functional association between physiological plasticity, climatic variability, and geographical latitude: Lessons from land snails

by Juan Diego Gaitán-Espitia

Co-authored with Daniel Naya, T. Catalan, P. Artacho and R. Nespolo.
Evolutionary Ecology Research, 2011

Background: The climatic variability hypothesis states that, as the range of climatic
fluctuation experienced by... more Background: The climatic variability hypothesis states that, as the range of climatic
fluctuation experienced by terrestrial animals increases with latitude, individuals at higher latitudes should be more plastic than individuals inhabiting lower latitudes. However, it is unclear whether comparatively high flexibility at higher latitudes is due to the direct effect of climatic variability or to other factors associated with latitude. Aim: To investigate the relationship between phenotypic flexibility, geographical latitude, and
climatic variability using a dataset where latitude and climatic variability are inversely related. Methods: We assessed the physiological plasticity to cope with thermal change (10C vs.
20C), at the level of metabolic rate and organ dry weight, in three populations of the brown garden snail (Cornu aspersum): Viña del Mar (3320S, 7132W), with high temperature and rainfall variability; Concepción (3647S, 737W), with a narrow range of temperature variability and intermediate rainfall variability; and Valdivia (3938S, 735W), with low temperature and rainfall variability. Results: Standard metabolic rate was higher at 20C than at 10C, but did not differ between
populations. Intestine dry weight did not differ among populations but it was higher at 20C than at 10C, particularly for individuals from the Viña del Mar and Conception populations. Hepatopancreas and kidney dry weight differed between populations, which was due to higher values in Viña del Mar at 20C. Conclusions: Flexibility in the weight of the organs analysed changed in a similar fashion
to annual temperature variation at each locality, suggesting that, as stated by the climatic variability hypothesis, climatic variability is the main force behind physiological plasticity.

Emerging amenity landscapes: Invasive weeds and land subdivision in rural Australia

by Nicholas Gill

With Peter Klepeis and Laurie Chisholm, Journal of Environmental Planning and Management, 53(3). 317-334

Changes in landownership associated with amenity migration are affecting the demographic, cadastral and ecological... more Changes in landownership associated with amenity migration are affecting the demographic, cadastral and ecological conditions of rural landscapes. These changes and concerns about their impacts on natural resource management, including ecological conservation, relate to both the structural consequences of landownership change, land subdivision and to the motivations, management ability and attitudes of lifestyle oriented rural landowners. Based on an Australian case study near Sydney, NSW, this paper examines the motivations and practices of such landowners, assesses potential consequences for vegetation and characterises the landowners according to three stewardship types

A functional trait perspective on plant invasion: invasiveness to impacts in a changing world.

by Christina Richards

Drenovsky*, R.E., B.J. Grewell*, C.M. D’Antonio, J.L. Funk, J.J. James, N. Molinari, I.M. Parker & C.L. Richards. 2012. A functional trait perspective on plant invasion: invasiveness to impacts in a changing world. Annals of Botany, doi: 10.1093/aob/mcs100. *shared first authorship.

† Background and Aims Global environmental change will affect non-native plant invasions, with profound potential... more † Background and Aims Global environmental change will affect non-native plant invasions, with profound potential impacts on native plant populations, communities and ecosystems. In this context, we review plant functional traits, particularly those that drive invader abundance (invasiveness) and impacts, as well as the integration of these traits across multiple ecological scales, and as a basis for restoration and management.
† Scope We review the concepts and terminology surrounding functional traits and how functional traits influence processes at the individual level. We explore how phenotypic plasticity may lead to rapid evolution of novel traits facilitating invasiveness in changing environments and then ‘scale up’ to evaluate the relative importance of demographic traits and their links to invasion rates. We then suggest a functional trait framework for assessing per capita effects and, ultimately, impacts of invasive plants on plant communities and ecosystems. Lastly, we focus on the role of functional trait-based approaches in invasive species management and restoration in the context of rapid, global environmental change.
†Conclusions To understand how the abundance and impacts of invasive plants will respond to rapid environmental changes it is essential to link trait-based responses of invaders to changes in community and ecosystem properties. To do so requires a comprehensive effort that considers dynamic environmental controls and a targeted approach to understand key functional traits driving both invader abundance and impacts. If we are to
predict future invasions, manage those at hand and use restoration technology to mitigate invasive species impacts, future research must focus on functional traits that promote invasiveness and invader impacts under changing conditions, and integrate major factors driving invasions from individual to ecosystem levels.

Invasive Species: To eat or not to eat, that is the question.

by Martin Nuñez

Nuñez, M. A., Kuebbing, S., Dimarco, R. D. & Simberloff, D. In Press. Invasive Species: To eat or not to eat, that is the question. Conservation Letters

Kiwi Apteryx mantelli population recovery through community-led trapping of invasive non-native mammals in Northland, New Zealand

by Al Glen

Glen, A. S., Hamilton, T., McKenzie, D., Ruscoe, W. A. and Byrom, A. E. . Conservation Evidence 9, 22-27.

In New Zealand, invasive non-native mammals threaten the survival of native species such as the North Island brown... more In New Zealand, invasive non-native mammals threaten the survival of native species such as the North Island brown kiwi (Apteryx mantelli). At Whangarei Heads, in northern New Zealand, community groups are working with local and national government agencies to protect kiwi populations. The abundance of kiwi there has been monitored since 2001 using annual counts of calls. Trapping of invasive mammals began in 2002, and their relative abundance is assessed from annual capture rates. Capture rates of stoats (Mustela erminea), weasels (M. nivalis), cats (Felis catus), rats (Rattus spp.) and possums (Trichosurus vulpecula) have declined significantly since trapping began, suggesting their abundance has been suppressed. Ferrets (Mustela furo) were already scarce when trapping began, and have been reduced to undetectable levels in most years. Numbers of hedgehogs (Erinaceus europaeus) have shown little response to trapping. Kiwi populations were apparently in decline before pest control began, but have since increased. Kiwi call rates in 2011 were the highest so far recorded at Whangarei Heads. Stoats are considered one of the main threats to kiwi, and our data suggest that kiwi numbers remain low unless stoat abundance is reduced below a catch per unit effort threshold of ~0.1 stoat per trap per year.

Metapopulation dynamics of a diadromous galaxiid fish and potential effects of salmonid aquaculture

by Sofia (Sonia) Consuegra del Olmo

Invasive plants and their ecological strategies: prediction and explanation of woody plant invasion in New England

by Chris Martine

Co-authored with Patrick M. Herron, Andrew M. Latimer, and Stacey A. Leicht-Young. Published in Diversity and Distributions, 2007. 13: 633-644.

Fifteen woody species with potential for invasiveness in New England

by Chris Martine

Co-authored with Patrick M. Herron, Andrew M. Latimer, and Stacey A. Leicht-Young. Published in Rhodora, 2008. 110: 345-353.

Introduced Abert’s squirrels in the Pinaleño Mountains: a review of their natural history and potential impacts on the red squirrel

by Andrew Edelman

Edelman, A.J., and J.L. Koprowski. 2009. Introduced Abert’s squirrels in the Pinaleño Mountains: a review of their natural history and potential impacts on the red squirrel. The Last Refuge of the Mt. Graham Red Squirrel: Ecology of Endangerment (H.R. Sanderson and J.L. Koprowski, eds.). University of Arizona Press, Tucson. Pp 370-388.

Selection of drey sites by Abert’s squirrels in an introduced population

by Andrew Edelman

Edelman, A.J., and J.L. Koprowski. 2005. Selection of drey sites by Abert’s squirrels in an introduced population. Journal of Mammalogy 86:1220-1226.

Potential for Nest Site Competition Between Native and Exotic Tree Squirrels

by Andrew Edelman

Edelman, A.J., J.L. Koprowski, and S.R. Bertelsen. 2009. Potential for nest site competition between native and exotic tree squirrels. Journal of Mammalogy 90:167-174.

Effects of climate change on the distribution of invasive alien species in Canada: a knowledge synthesis of range change projections in a warming world

by Nina Hewitt

Plant species richness increases resistance to invasion by non-resident plant species during grassland restoration

by Clinton Oakley

Clinton A. Oakley, John S. Knox. 2012. Applied Vegetation Science.

Questions
During restoration of bare subsoil, are planted grassland communities with low species richness more... more Questions
During restoration of bare subsoil, are planted grassland communities with low species richness more susceptible to invasion by non-residents than communities augmented by additional species? What are the mechanisms of invasion resistance in early succession?

Location
Lexington, Virginia, USA (37.8°N, −79.4°W).

Methods
We planted 62 3 × 3 m plots on compacted clay subsoil with 20–21 replicates of three, 12 and 24 native species. Plots were sampled non-destructively using a stratified random point-intercept method each summer for 5 yr to determine number of species and percentage cover per species, which were classified as residents (planted), internal non-residents (planted in other plots) or external non-residents.

Results
A negative relationship between planted species richness and invasion developed by the fourth year after planting and strengthened thereafter. Plots consisting of a single, highly dominant, resident C3 grass species were vulnerable to invasion. With the exception of one species, which seems to have overcome resistance with a high seed rain, external non-resident species were less diverse and less abundant in higher diversity plots.

Conclusions
Increased planted species richness was correlated with increased resistance to invasion by non-residents, and we attribute this effect to a combination of the sampling effect and species complementarity, potentially augmented by high species dominance/low evenness in the low species richness plots.

A call for action to curb invasive species in South America

by Karina L. Speziale

Speziale K.L. and Lambertucci S.A. 2010. Nature

Patterns of alien plant invasions in northwestern Patagonia, Argentina

by Karina L. Speziale

Speziale, K. & Ezcurra C. J. Arid Environments (In press) Speziale, K. & Ezcurra C. J. Arid Environments (In press)

Dealing with non-native species: what makes the difference in South America?

by Karina L. Speziale

Epigenetic variation may compensate for decreased genetic variation with introductions: a case study using house sparrows (Passer domesticus) on two continents.

by Christina Richards

Schrey, A.W., C.A.C. Coon, M.T. Grispo, M. Awad, T. Imboma, E.D. McCoy, H.R. Mushinsky, C.L. Richards & L.B. Martin. 2012. Epigenetic variation may compensate for decreased genetic variation with introductions: a case study using house sparrows (Passer domesticus) on two continents. Genetics Research International 2012: Article ID 979751.

Epigenetic mechanisms impact several phenotypic traits and may be important for ecology and evolution. The introduced... more Epigenetic mechanisms impact several phenotypic traits and may be important for ecology and evolution. The introduced house sparrow (Passer domesticus) exhibits extensive phenotypic variation among and within populations. We screened methylation in populations from Kenya and Florida to determine if methylation varied among populations, varied with introduction history (Kenyan invasion <50 years old, Florida invasion ∼150 years old), and could potentially compensate for decrease genetic variation with introductions. While recent literature has speculated on the importance of epigenetic effects for biological invasions, this is the first such study among wild vertebrates. Methylation was more frequent in Nairobi, and outlier loci suggest that populations may be differentiated. Methylation diversity was similar between populations, in spite of known lower genetic diversity in Nairobi, which suggests that epigenetic variation may compensate for decreased genetic diversity as a source of phenotypic variation during introduction. Our results suggest that methylation differences may be common among house sparrows, but research is needed to discern whether methylation impacts phenotypic variation.

The natives are restless, but not often and mostly when disturbed.

by Martin Nuñez

Simberloff, D., Souza, L., Nuñez, M.A., Barrios, M.N. & Bunn, W. 2012. The natives are restless, but not often and mostly when disturbed. Ecology 93

Assessment of risks to non-target species from an encapsulated toxin in a bait proposed for control of feral cats.

by Al Glen

de Tores, PJ, Sutherland, DR, Clarke, JR, Hill, RF, Garretson, SW, Bloomfield, L, Strümpher, L, Glen, AS and Cruz, J (2011). Wildlife Research 38: 39-50.

Context. The CURIOSITY® bait is the name coined for a variation of the existing sausage-style cat bait, ERADICAT®. The... more Context. The CURIOSITY® bait is the name coined for a variation of the existing sausage-style cat bait, ERADICAT®. The latter is used under experimental permit in Western Australia for research associated with cat control. The CURIOSITY bait differs from ERADICAT by providing a pH-buffered (less acidic) medium and has been proposed to reduce the risk to non-target species by encapsulating a toxin in a pellet.Wetrialled a prototype pellet proposed for encapsulation of 1080 and/ or alternative toxins, with delivery proposed through the CURIOSITY bait.

Aim. Our aim was to determine whether the pellet was consumed by non-target native species from south-west of Western Australia.

Methods. Trials involved use of a non-toxic biomarker, Rhodamine B, encapsulated within the pellet and inserted into the CURIOSITY® bait. Uptake of the encapsulated biomarker was assessed in captive trials for the target species, the feral cat (Felis catus) and two non-target species of varanid lizard, Rosenberg’s goanna (Varanus rosenbergi) and Gould’s goanna (V. gouldii) and the non-target mammal species chuditch (Dasyurus geoffroii) and southern brown bandicoot (Isoodon obesulus). Uptake of the encapsulated biomarker was also assessed in field trials for a range of native species.

Key results. Captive trials demonstrated feral cats will consume the CURIOSITY bait and pellet. However, results from captive and field trials indicated several non-target species also consumed the bait and pellet. We also found the pellet itself was not sufficiently robust for use in a bait. As with previously reported studies, we found Rhodamine B to be an effective biomarker for use in cats. We also developed a technique whereby Rhodamine B can be used as a biomarker in reptiles. However, its use as a biomarker in other mammalian species was confounded by what appeared to be background, or pre-existing, levels of fluorescence, or banding, in their whiskers.

Conclusion. The prototype pellet is unsuitable in its current form for use with the CURIOSITY bait. We caution that the CURIOSITY bait has non-target issues in south-west of Western Australia and any proposed variations to this bait, or the ERADICAT® bait, need to be rigorously assessed for their potential risk to non-target species and assessed for the level of uptake by cats, irrespective of their suitability/unsuitability as a medium for delivery of an encapsulated toxin. We believe the threat to biodiversity-conservation values from unmitigated feral-cat predation of native fauna poses a significant and real threat and we recommend urgent investment of resources to address the issue of cat predation in a coordinated and collaborative manner within Australia and New Zealand.

Density and habitat use by the round goby ( Apollonia melanostoma) in the Bay of Quinte, Lake Ontario

by Carolina Taraborelli