Genetic Diversity in Invasive Populations of Lupinus polyphyllus Lindl. and Heracleum sosnowskyi Manden.

In our study, two aggressive-invasive species, Lupinus polyphyllus Lindl. and Heracleum sosnowskyi Manden. from Russia and Ukraine, were investigated. The success in naturalization of both species is associated with human activities, since they have been used in agriculture and floriculture and both have qualities such as environmental tolerance, high fertility and phenotypic plasticity. The purpose of this study was to determine the level of genetic diversity of both species. For Heracleum sosnowskyi Manden., genetic diversity was compared in invasive and native populations. For Lupinus polyphyllus Lindl., the genetic diversity was compared in variety, feral and invasive populations. A genetic diversity was formulated using RAPD, ISSR and REMAP. For Heracleum sosnowskyi Manden., the average genetic diversity within the invasive population was similar (0.432), but slightly less (0.502) than within the native Caucasian population. This may suggest the successful naturalization of invaders and almost complete reconstruction of their genetic diversity. For Lupinus polyphyllus Lindl., the genetic diversity for the invasive population was the highest, with an average of 0.294, while for variety, it was the lowest, with an average of 0.194. The feral population had an intermediate place with an average of 0.248, which could suggest an increase of diversity in the process of naturalization.

Playing dead: lizards show tonic immobility without human handling

Tonic immobility, or the ability to play dead, is widespread among vertebrates. It is a last line of defence against a threat, and usually follows physical restraint. Here, I report two lizards exhibiting tonic immobility in the presence of humans, but remarkably, without any handling or physical contact. These two lizards belonged to an invasive population of the Italian Wall Lizard (Podarcis siculus), and both events took place in different years and situations, suggesting this behaviour may be more common than previously thought. There are rare documented cases of animals exhibiting this behaviour without handling; however, to my knowledge, this is the first description of a lizard displaying tonic immobility to humans, in the absence of handling. This is also the first incident of tonic immobility in the Italian Wall Lizard. I discuss these anecdotal events in the light of this invasive population inhabiting a highly urbanized location.

The Horseshoe whip snake (Hemorrhois hippocrepis) on Ibiza: predator release in an invasive population

The key to fighting a biological invasion may lie in understanding every variable that can explain its success. The Enemy Release Hypothesis (ERH) states that when an invader arrives to a new environment, the absence of its common enemies (predators, parasites and competitors) facilitates the invasion success. The Horseshoe whip snake (Hemorrhois hippocrepis) has been recently introduced from the Iberian Peninsula to the island of Ibiza, and it is currently threatening the only endemic vertebrate, the Ibiza wall lizard (Podarcis pityusensis). We hypothesized that the snake invasion success is caused by the absence of natural predators, and we checked the ERH by relating the tail breakage rate to predation pressure. The invasive population showed a much lower incidence of tail breakage than the source population, which is in agreement with the almost absence of snake predators among the Ibizan reduced and naïve native vertebrate community. These results confirm the ERH, and support the prolongation of invasive snake trapping campaigns.

Increased immune marker variance in a population of invasive birds

Immunity and parasites have been linked to the success of invasive species. Especially lower parasite burden in invasive populations has been suggested to enable a general downregulation of immune investment (Enemy Release and Evolution of Increased Competitive Ability Hypotheses). Simultaneously, keeping high immune competence towards potentially newly acquired parasites in the invasive range is essential to allow population growth. To investigate the variation of immune effectors of invasive species, we compared the mean and variance of multiple immune effectors in the context of parasite prevalence in an invasive and a native Egyptian goose (Alopochen aegyptiacus) population. Three of ten immune effectors measured showed higher variance in the invasive population. Mean levels were higher in the invasive population for three effectors but lower for eosinophil granulocytes. Parasite prevalence depended on the parasite taxa investigated. We suggest that variation of specific immune effectors, which may be important for invasion success, may lead to higher variance and enable invasive species to reduce the overall physiological cost of immunity while maintaining the ability to efficiently defend against novel parasites encountered.

The ontogenesis and structure of coenopopulations of Pulsatilla uralensis in the conditions of Northern Kazakhstan

The age features of ontogenesis and the structure of coenopopulations of Pulsatilla uralensis (Zam.) Tzvel., on the territory of Kostanay region were studied. Coenopopulations of P. uralensis are confined to forest edges or secondary steppe communities on the site of old hares on soils of light mechanical composition. There are three periods and 7 age States in ontogeny: seedlings, juvenile, immature virginal, young, middle-aged, old-age generative, and sub-senile states. A feature of the age states of P. uralensis in comparison with the Siberian and Yakut populations is the earlier division of rhizomes into separate parcels with the formation of a loose caudex, observed in the middle-aged generative state. In a sparse pine forest, a normal population is formed with a predominance of generative individuals, belonging to mature populations with a low recovery index. Populations formed in the conditions of secondary psammophytic steppe on the site of a burned pine forest, a left-sided invasive population is formed with a predominance of immature and virginal individuals, which has a high recovery index.

Matching a snail’s pace: Successful use of environmental DNA techniques to detect early stages of invasion by the destructive New Zealand mud snail

ABSTRACTEarly detection of invasive species allows for a more rapid and effective response. Restoration of the native ecosystem after an invasive population has established is expensive and difficult but more likely to succeed when invasions are detected early in the invasion process. Containment efforts to prevent the spread of known invasions also benefit from earlier knowledge of invaded sites. Environmental DNA (eDNA) techniques have emerged as a tool that can identify invasive species at a distinctly earlier time point than traditional methods of detection. Due to expected range expansion in eastern North America, we focus on the destructive New Zealand Mud Snail Potamopyrgus antipodarum (NZMS) invasion. We collected water samples from eight sites that prior evidence indicated were not yet invaded by the NZMS. After filtering these samples to collect eDNA, we used a species-specific probe with qPCR to identify NZMS eDNA. We found evidence for NZMS invasion at five of the eight sites, with later physical confirmation of mud snails at one of these sites. This study is the first example of successful detection of a previously unidentified invasive population of NZMS, setting the stage for further monitoring of at-risk sites to detect and control new invasions of this destructive snail. This study also shows potential opportunities for invasion monitoring offered by using low-cost efforts and methods that are adaptable for citizen science.