Search results for "tulokaslajit"

Passive sinking into the snow as possible survival strategy during the off-host stage in an insect ectoparasite

2015

Abiotic and biotic factors determine success or failure of individual organisms, populations and species. The early life stages are often the most vulnerable to heavy mortality due to environmental conditions. The deer ked (Lipoptena cervi Linnaeus, 1758) is an invasive insect ectoparasite of cervids that spends an important period of the life cycle outside host as immobile pupa. During winter, dark-coloured pupae drop off the host onto the snow, where they are exposed to environmental temperature variation and predation as long as the new snowfall provides shelter against these mortality factors. The other possible option is to passively sink into the snow, which is aided by morphology of …

Inheritance patterns of photoperiodic diapause induction in Leptinotarsa decemlineata

2016

Photoperiod is a reliable indicator of season and an important cue that many insects use for phenological synchronization. Undergoing range expansion insects can face a change in the local photoperiod to which they need to resynchronize. Rapid range expansion can be associated with rapid photoperiodic adaptation, which can be associated with intense selection on strongly heritable polygenic traits. Alternatively, it is proposed that, in insects with an XO sex-determination system, genes with large effect residing on the sex chromosome could drive photoperiodic adaptation because the gene or genes are exposed to selection in the sex carrying only a single X-chromosome. The present study seek…

Are the effects of an invasive crayfish on lake littoral macroinvertebrate communities consistent over time?

2016

Management of invasive species requires assessment of their effects on recipient ecosystems. However, impact assessment of invasive species commonly lacks a long-term perspective which can potentially lead to false conclusions. We examined the effects of the invasive signal crayfish (Pacifastacus leniusculus Dana) on the stony littoral macroinvertebrate communities of a large boreal lake and assessed the extent to which the patterns observed in previous short-term studies were stable over time. We used temporal macroinvertebrate data collected in five consecutive years from a site with a well-established crayfish population, a site with no crayfish and a site where crayfish had been recentl…

Ecological impacts of invasive signal crayfish in large boreal lakes

2012

Invasion triple trouble : environmental fluctuations, fluctuation-adapted invaders and fluctuation-mal-adapted communities all govern invasion success

2017

AbstractIt has been suggested that climate change will lead to increased environmental fluctuations, which will undoubtedly have evolutionary consequences for all biota. For instance, fluctuations can directly increase the risk of invasions of alien species into new areas, as these species have repeatedly been proposed to benefit from disturbances. At the same time increased environmental fluctuations may also select for better invaders. However, selection by fluctuations may also influence the resistance of communities to invasions, which has rarely been tested. We tested eco-evolutionary dynamics of invasion with bacterial clones, evolved either in constant or fluctuating temperatures, an…

Eco-physiological aspects of adaptation to seasonal environments : the latitudinal range expansion of the Colorado potato beetle across Europe

2013

Range expansion to novel environments : evolutionary physiology and genetics in Leptinotarsa decemlineata

2010

Jokiravun (Astacus astacus) ja täpläravun (Pacifastacus leniusculus) sopeutuminen virtavesiin

2008

Indirect effects of invasive crayfish on native fish parasites

2013

Interactions between invasive and native species are often modified by parasites. One little-studied scenario is that invasive species affect parasite transmission to native hosts by altering the relative abundance of hosts needed in parasite life cycles, for example by predation on these hosts. Here we show that presence of an invasive crayfish species, Pacifastacus leniusculus, decreases the mean abundance of native parasites transmitted from snails and aquatic isopods to perch, Perca fluviatilis, in two large boreal lakes in Finland. In contrast, parasites transmitted to the fish from planktonic copepods or mussels, hosts not readily preyed on by crayfish, were not affected by crayfish p…

Pre-invasion history and demography shape the genetic variation in the insecticide resistance-related acetylcholinesterase 2 gene in the invasive Col…

2012

Abstract Background Invasive pest species offers a unique opportunity to study the effects of genetic architecture, demography and selection on patterns of genetic variability. Invasive Colorado potato beetle (Leptinotarsa decemlineata) populations have experienced a rapid range expansion and intense selection by insecticides. By comparing native and invasive beetle populations, we studied the origins of organophosphate (OP) resistance-associated mutations in the acetylcholinesterase 2 (AChE2) gene, and the role of selection and demography on its genetic variability. Results Analysis of three Mexican, two US and five European populations yielded a total of 49 haplotypes. Contrary to the exp…