Thesis (MScAgric)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Invasion by the notorious tramp species, the Argentine ant (Linepithema humile Mayr) (Hymenoptera: Formicidae) has caused major concern around the globe, owing to its displacement of native ant species and other invertebrates where it invades. This species was first recorded in South Africa in 1901 in Stellenbosch, Western Cape Province (WCP), and has now become a significant pest in most urban and agricultural areas in the country. The Argentine ant has received relatively little attention in South Africa compared to other countries (e.g. California, North America). To date the extent of invasion by this species countrywide, as well as its impact on the local ant fauna inside protected areas, has not been quantified. In this study, the impact of the Argentine ant on native ant fauna inside three protected areas in the WCP (Helderberg Nature Reserve (HNR), Jonkershoek Nature Reserve (JNR) and Kogelberg Biosphere Reserve KBR)) was assessed. Species richness and diversity were compared between invaded and uninvaded bait stations at each protected area. Several native ant species were found to be displaced by the Argentine ant from all three protected areas, although three species: Meranoplus peringueyi, Monomorium sp. 8 and Tetramorium quadrispinosum, were found coexisting with it. Invaded bait stations had significantly lower ant species richness and species turnover than uninvaded bait stations. Uninvaded bait stations contained eight times more native ant species than invaded bait stations. Thus, the invasion of protected areas by the Argentine ant has severe negative consequences for the species richness and assemblage structure of native ants, leading to the biotic homogenization of these local ant communities. The distribution range of the Argentine ant inside the three protected areas (HNR, JNR, KBR), as well as microhabitat preferences that may facilitate the spread of this species inside these reserves, was also assessed. Helderberg Nature Reserve was the most invaded protected area, with the highest level of the Argentine ant occupancy, while JNR and KBR had lower occupancy levels. At all the three protected areas, this species was dominant at lower altitudinal areas, and also showed a clear preference for areas with high anthropogenic disturbances, i.e. around buildings and on lawns (picnic areas). In this study, there was no evidence that moisture availability facilitates the distribution and spread of the Argentine ant inside these reserves. Finally, a combination of published literature records, museum records and records collected in the current study was used to quantify the current distributional extent of the Argentine ant throughout urban South Africa. This is the first study quantifying the distribution and extent of invasion by the Argentine ant throughout the country. The Argentine ant was found in six of the nine South African Provinces, and its extent of occurrence includes approximately half of the country’s land surface area. Discontinuities in the distribution of the Argentine ant across the country revealed that range expansion of the Argentine ant in South Africa is occurring predominantly via human-mediated jump dispersal, rather than naturally via nest diffusion. This study clearly demonstrated that the Argentine ant is well established across South Africa as well as inside protected areas. The Argentine ant invasion was influenced by the presence of human modified landscapes (i.e. buildings) both at low and high altitude, and this was associated with higher rates of native ant species displacement at these areas. Therefore, limiting the development of recreational areas, such as buildings and picnic sites inside protected areas will result in the lower rate of spread of the Argentine ant. This will in turn lower the extent of displacement of native ant species. / AFRIKAANSE OPSOMMING: Indringing deur die Argentynse mier (Linepithema humile Mayr) (Hymenoptera: Formicidae) is ‘n bron van groot kommer regoor die wêreld, as gevolg van sy vermoë om inheemse mier spesies en ander ongewerweldes te verplaas. Hierdie spesie is vir die eerste keer aangeteken in Suid-Afrika in 1901, in Stellenbosch, Weskaap Provinsie (WCP), en het ‘n belangrike pes geword in die meeste stedelike en landelike gebiede in die land. Die Argentynse mier het betreklik min aandag gekry in Suid-Afrika, in vergelyking met ander lande (bv. California, Noord Amerika). Tans is die omvang van die landwye indringing van hierdie spesie, sowel as sy impak op die plaaslike mier fauna binne beskermde areas, nog nie bepaal nie. In hierdie studie word die impak van die Argentynse mier op die inheemse mier fauna binne drie beskermde areas in die WCP (Helderberg Natuurreservaat (HNR), Jonkershoek Natuurreservaat (JNR) en Kogelberg Biosfeerreservaat (KBR)) bepaal. Spesierykheid en diversiteit was vergelyk tussen ingedringde en oningedringde lokaas stasies in elke beskermde area. Verskeie inheemse mier spesies was deur die Argentynse mier verplaas in al drie beskermde areas, alhoewel drie spesies: Meranoplus peringueyi, Monomorium sp. 8 en Tetramorium quadrispinosum het saam met dit voorgekom. Ingedringde lokaas stasies het beduidend laer mier spesierykheid en spesies omset gehad as oningedringde lokaas stasies. Dus, die indringing van beskermde areas deur die Argentynse mier het ernstige negatiewe gevolge vir die spesierykheid en gemeenskap struktuur van inheemse miere, wat lei tot die biotiese verarming van hierdie plaaslike mier gemeenskappe. Die verspreidingsarea van die Argentynse mier binne die drie beskermde areas (HNR, JNR, KBR), en die mikrohabitat voorkeure wat die verspreiding van die spesie binne hierdie reservate kan vergemaklik, was ook vasgestel. Helderberg Natuurreservaat was die mees ingedringde beskermde area, met die hoogste vlak van Argentynse mier besetting, terwyl JNR en KBR laer besettingsvlakke gehad het. By al drie die beskermde areas was hierdie spesie dominant by laer hoogtes bo seevlak en het ‘n duidelike voorkeur getoon vir areas met hoë menslike versteuring d.i. rondom geboue en op grasperke (piekniek areas). In hierdie studie was daar geen bewyse dat vog beskikbaarheid die voorkoms en verspreiding van die Argentynse mier binne die reservate vergemaklik nie. Ten slotte, ‘n kombinasie van gepubliseerde literatuur verslae, museum dokumente en verslae wat in hierdie studie versamel is, was gebruik om die huidige verspreidingsomvang van die Argentynse mier te bepaal. Dit is die eerste studie wat die verspreiding en omvang van indringing in stedelike Suid Afrika van die Argentynse mier dwarsdeur die land bepaal. Die Argentynse mier is gevind in ses van die nege provinsies in Suid-Afrika, en die omvang van sy voorkoms sluit bykans die helfte van die land se landoppervlaksarea in. Onderbrekings in die verspreiding van die Argentynse mier deur die land het blootgelê dat die uitbreiding van die voorkomsgebied van die Argentynse mier in Suid-Afrika hoofsaaklik gebeur deur mens bemiddelde verspreiding eerder as natuurlike nesverspreiding. Hierdie studie het duidelik gedemonstreer dat die Argentynse mier goed gevestig is regoor Suid-Afrika sowel as in beskermde areas. Die Argentynse mier indringing was beïnvloed deur mensgewysigde landskappe (d.i. geboue) by lae en hoë hoogtes bo seevlak, en dit was verwant aan hoër vlakke van verplasing van inheemse mier species in hierdie areas. Dus, die beperking van ontwikkeling van rekreasie areas, soos geboue en piekniekareas, in beskermde gebiede sal lei tot laer vlakke van verspreiding van die Argentynse mier. Dit sal, op sy beurt, die omvang van verplasing van die inheemse mier spesies verminder.

Thesis (PhD (Botany and Zoology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Although the impacts of biological invasions are widely appreciated, a bias exists in research effort to post‐dispersal processes because of the difficulties of measuring propagule pressure and the detecting of newly established species. Here the Antarctic is used as a model system in which to quantify the initial dispersal of alien species and investigate the factors that contribute to the establishment and range dynamics of alien species once they have arrived in the region. Human movements are known to transport alien species into the Antarctic, some of which have successfully established and had wide ranging consequences in recipient ecosystems. Considering terrestrial flora, this research found that over 700 seeds from 99 taxa, including some species known to be invasive, are transported into the Antarctic each year in association with South African National Antarctic Programme (SANAP) passenger luggage and cargo. The first ever assessment of propagule drop‐off indicated that 30‐50% of these propagules will enter the recipient environment. Further results suggested that the construction of the British Antarctic Survey Halley VI station will facilitate the transport of over 5000 seeds from 34 taxa into the region, making this a significant pathway for introductions. Propagule pressure due to SANAP logistics is also considerable for marine species. Fouling assemblages on the external hull surfaces of the SANAP resupply vessel, the SA Agulhas, form only once the vessel’s anti‐fouling paint has been damaged by travel through sea ice and are characterised by low diversity. Ice scour prevents fouling assemblages from being transported to the Antarctic continent, but assemblages remain largely intact when travelling to sub‐Antarctic Islands. In the sea‐chests of the vessel populations of a known invasive, Mytilus galloprovincialis, were found with some individuals having survived transportation to the Antarctic region on multiple occasions. Once species have overcome initial dispersal barriers, they face further ecological and physiological challenges in order to establish in the recipient region. The parasitoid wasp Aphidius matricariae was first recorded on Marion Island in 2001. Surveys around the island show that adult abundance and the frequency of aphid parasitism are highest adjacent to a common anchor point of the SA Agulhas and decline away from this region. Genetic diversity was low, suggesting that the population was established from a single introduction. This highlights that high propagule pressure is not necessary for successful establishment of introduced invertebrates. Another species that has overcome the dispersal barrier is the terrestrial slug Deroceras panormitanum, which was introduced to Marion Island in the 1970’s and has since spread throughout much of the coastal habitat of the island. For this species range limits are set by intolerance of low temperature and salinity, and abundance structure is characterized by patches and gaps which are associated with this species inability to tolerate dry conditions. To prevent further alien introductions in the region, targeted management of high risk pathways is required. In addition, increased vigilance is needed to detect and manage newly established aliens before their ranges expand. / AFRIKAANSE OPSOMMING: Alhoewel die impak van biologiese indringings in die breë waardeer word, bestaan daar vooroordeel in navorsingspogings ten opsigte van na‐verspreidingsprosesse, weens die moeilikhede om verspreidingseenheid druk te meet en in die opsporing van nuut gevestigde spesies. Hier word die Antarktiese streek as ‘n model sisteem gebruik waarin die aanvanklike verspreiding van uitheemse spesies gekwantifiseer kan word en om die faktore wat bydrae tot die vestiging en grens dinamika van uitheemse spesies te ondersoek, wanneer hulle in ’n streek aangekom het. Menslike bewegings is bekend daarvoor om uitheemse spesies na die Antarktiek te vervoer, sommige waarvan suksesvol gevestig het en omvattende gevolge in die ontvanger ekosisteme gehad het. Aangaande terrestriële flora het hierdie navorsing gevind dat oor die 700 sade van 99 taxa, insluitende sommige spesies wat bekend is om indringend te wees, jaarliks na die Antarktiek vervoer word in assosiasie met die Suid Afrikaanse Nasionale Antarktiese Program (SANAP) se bagasie en vrag. Die eerste waardebepaling van verspreidingseenheid afgooi het aangedui dat 30‐50% van hierdie verspreidingseenhede die ontvanger omgewing sal binnedring. Verdere resultate het voorgestel dat die konstruksie van die Britse Antarktiese Opname Halley VI stasie die vervoer van 5000 sade van 34 taxa sal fasiliteer die streek in, wat dit ’n betekenisvolle weg maak vir indringings. Verspreidingseenheid druk is ook, as gevolg van die SANAP logistiek, aanmerklik vir mariene spesies. Vuilgoed versamelings op die eksterne omhullende oppervlaktes van die SANAP her‐voorsieningsvaartuig, die SA Agulhas, vorm wanneer die vaartuig se anti‐vuilgoed verf beskadig is met reis deur see‐ys en word gekenmerk deur lae diversiteit. Ys skuring voorkom dat vuilgoed versamelings vervoer word na die Antarktiese kontinent, maar versamelings bly grootliks vasgeheg wanneer na sub‐Antarktiese eilande gereis word. Populasies van ’n welbekende indringer, Mytilus galloprovincialis, is gevind in die see‐storingsarea van die vaartuig, met sommige individue wat die vervoering na die Antarktiese streek oorleef het op verskeie geleenthede. Wanneer spesies die aanvanklike verspreidingshindernisse oorkom het, staar hulle verdere ekologies en fisiologiese uitdagings in die gesig ten einde in die ontvanger streek te vestig. Die parasitiese wespe Aphidius matricariae is vir die eerste keer op Marion aangeteken in 2001. Opnames om die eiland toon dat volwasse oorvloed en die frekwensie van plantluis parasitisme die hoogste is aangrensend die algemene ankerpunt van die SA Agulhas en afneem weg van die omgewing af. Genetiese diversiteit was laag, wat voorstel dat die populasie gevestig het van ’n enkele bekendstelling. Dit lig uit dat hoë verspreidingseenheid druk nie nodig is vir die suksesvolle vestiging van bekendgestelde invertebrata nie. ‘n Ander spesie wat die verspreidingshindernisse oorkom het is die landslak Deroceras panormitanum wat in die 1970’s op Marion Eiland bekendgestel is en wat sedertdien versprei het oor meeste van die kushabitat van die eiland. Vir hierdie spesie word grens limiete vasgestel deur onverdraagsaamheid vir lae temperature en saliniteit en die oorvloedstruktuur word gekenmerk deur laslappe en gapings wat geassosieer word met die spesie se onvermoë om droë kondisies te hanteer. Om verdere uitheemse bekendstellings in die streek te voorkom, word geteikende bestuur van hoë risiko weë vereis. Toenemende waaksamheid is bykomend nodig vir die opsporing en bestuur van nuutgevestigde uitheemse spesies voordat hulle grense verbreed.

Invasive non-native species are believed to be one of the biggest threats to biodiversity. Until now biological invasions have been mainly studied from a biological perspective and much research has been undertaken to investigate species’ ecology and potential options for management. Comparatively little attention has been devoted to questions regarding the social construction of the issue. This is despite invasion biologists increasingly acknowledging the fundamental importance of human perceptions, beliefs, attitudes and values inherent in debates about invasive non-native species. This thesis employs a mix of methods from the social sciences to investigate the social construction of biological invasions. Research conducted here is based on the theory of social representations. Thus, taking a social scientific perspective, the thesis contributes to both the development of the theory and an identification of beliefs inherent in the debate on biological invasions and their relationship to people’s attitudes towards species and their management. Those species attributes that predominantly shape the debate – but yet appear to be under-researched – are identified. Based on the findings in this thesis I argue that invasion biology would benefit from a more explicit and transparent use of its concepts and terminology. This will have implications also for the communication with policy makers, conservation managers and the general public. Recommendations for future research are discussed along with limitations of the thesis.

La lutte biologique est souvent présentée comme une méthode de lutte contre les ravageurs respectueuse de l'environnement, même si la lutte par acclimatation (introduction d'une espèce exotique) peut être à l'origine d'invasion biologique. La coccinelle asiatique Harmonia axyridis Pallas (Coleoptera : Coccinellidae) a été utilisée comme agent de lutte biologique introduit en Amérique et en Europe pour lutter contre les pucerons. Actuellement, cette espèce est considérée comme envahissante, et a des impacts négatifs sur l'environnement. L'objectif principal de cette thèse est d'améliorer notre connaissance des processus évolutifs pouvant accompagner l'élevage en captivité, ainsi que ceux qui sont liés aux invasions biologiques. J'ai pour cela utilisé une approche expérimentale au travers d'études permettant de caractériser les différences de traits d'histoire de vie entre les trois compartiments populationnels d'H. axyridis (populations natives, envahissantes et de lutte biologique). Les résultats obtenus montrent que les changements évolutifs les plus importants concernent le compartiment de lutte biologique par rapport aux compartiments sauvages (natifs et envahissants). Ce compartiment a subi des changements phénotypiques remarquables en réponse aux conditions d'élevage en laboratoire. Les changements évolutifs les plus spectaculaires concernent différents traits liés à la reproduction. Par exemple, les femelles de lutte biologique se reproduisent plus tôt, ont une fécondité journalière plus élevée, ainsi qu'une longévité et une durée de vie reproductive plus courte. Nous avons également mis en évidence des changements évolutifs entre des populations sauvages natives et envahissantes. Les adaptations aux conditions d'élevage peuvent parfois être désavantageuses dans l'environnement naturel. Par exemple, la résistance au froid et aux pathogènes est moins importante que celle des populations sauvages. Nos résultats montrent aussi que, même si la souche de lutte biologique européenne est incapable de s'implanter dans la nature, l'hybridation avec les populations envahissantes américaines pourrait avoir jouer un rôle positif au cours de l'invasion en Europe. / Biological control is generally considered as an environmentally low-impact solution for pest control. However, the use of foreign control agents may ultimately lead to undesired biological invasions. The Asian harlequin ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae) was originally used as a biological control agent of aphids in North America and Europe. This species is now considered as invasive, and can have harmful effects on the environment. The main objective of this thesis is to better understand the impact of mass rearing on life-history traits, with a focus on traits that may be associated with invasion success. To do so, experimental approaches were carried out to monitor changes in life-history traits for three types of populations (biocontrol, native or invasive). The corresponding results indicate that the most important evolutionary changes occur in the biocontrol populations (by contrast with the invasive and native populations). Mass rearing appears to induce significant phenotypic changes in the biocontrol populations, with the most spectacular changes being related to reproductive life-history traits. For instance, biocontrol females reproduce significantly earlier, have a higher daily fecundity, but also exhibit lower life expectancy and lower reproductive lifespan. We also evidence other differences between the native and invasive populations. Cold tolerance and pathogen resistance are also lower in biocontrol populations than in wild populations. Altogether, our findings indicate that adaptations to mass rearing conditions may affect the fitness of H. axyridis populations in natural environments. This suggests that, even if the European biocontrol strain is unable to successfully colonize a natural environment, it may nonetheless impact the invasion dynamics of the species in Europe thanks to the admixture with the invasive American population

MSc., Faculty of Science, University of the Witwatersrand, 2011 / This research investigated the susceptibility of South African indigenous aquatic plants to competition from invasive species, using the competitive interactions of two sets of aquatic plants as a potential indicator. These interactions were studied in two separate experiments: the submersed weeds, Hydrilla verticillata (L.F.) Royle (Hydrocharitaceae) and an indigenous species, Lagarosiphon major (Ridley) Moss (Hydrocharitaceae) and; the floating weeds, Azolla filiculoides Lamarck (Azollaceae) and the indigenous Spirodela polyrhiza (L.) Schleid (Lemnaceae). Plants were grown under differing nutrient levels, and in an addition series of eight different densities, using the reciprocal yield model to estimate competitive ability. The invasive Hydrilla outcompeted Lagarosiphon in terms of mean length, dry mass, and survival. Major algal infestation in the high nutrient level of the Hydrilla/Lagarosiphon experiment altered light and nutrient conditions, which may have played a significant role in the lack of establishment of Lagarosiphon and the poor growth performance of Hydrilla. The invasive Azolla and indigenous Spirodela both performed well in terms of plant mass and increase in number. While Azolla was affected by intraspecific competition, it showed a steady increase in growth and multiplication with an increase in nutrients. The individual mass of Spirodela plants was highest in the low nutrient level, and multiplication rates were greatest in the high nutrient level. Results indicate that the susceptibility of indigenous plants may be increased in highnutrient systems, and that a continuous monitoring programme of aquatic alien species is vital in protecting our indigenous plants from extinction. This research recommends that the method of investigating competitive interactions between alien and indigenous plants be repeated with a variety of aquatic plants, as a means of anticipating susceptibility to invasions.

The spread of nonnative invasive species has become the second greatest threat to global biodiversity, making management of invasive species a critical component of the conservation of biodiversity worldwide. Managers and conservation biologists often lack basic life history data, as well as quantitative and theoretical models to predict risk of invasion or other negative effects. I contribute information to both categories by providing life history information (diet and morphology) of the Purple Swamphen (Porphyrio porphyrio) and by characterizing the invasion pathways that nonnative avian species in Florida follow. I found Purple Swamphens are predominantly eating and selecting for Eleocharis cellulosa. Additionally, there is a large amount of variation in nonnative avian species’ propensity to colonize natural habitat and the time it takes to do so. Nine out of 15 species investigated colonized natural habitat and the time it took them to do so ranged from 8 to 41 years. It is through a combination of various techniques that ecologists will begin to fully understand the importance of studying nonnative species as well as reducing the impact that nonnatives have on native ecosystems. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015 / FAU Electronic Theses and Dissertations Collection

Biological invasions are devastating ecosystems and economies world-wide, while many native species' survival depends on their ability to track climate change. Characterising the spread of biological populations is therefore of utmost importance, and can be studied with spatially explicit, discrete-time integro-difference equations (IDEs), which reflect numerous species' processes of demography and dispersal. While spatial variation has often been ignored when implementing IDE models, real landscapes are rarely spatially uniform and environmental variation is crucial in determining biological spread. To address this, we use novel methods to characterise population spread in heterogeneous landscapes. Asymptotic analysis is used for highly fragmented landscapes, where habitat patches are isolated and smaller than the dispersal scale, and in landscapes with low environmental variation, where the ecological parameters vary by no more than a small factor from their mean values. We find that the choice of dispersal kernel determines the effect of landscape structure on spreading speed, indicating that accurately fitting a kernel to data is important in accurately predicting speed. For the low-variation case, the spreading speeds in the heterogeneous and homogeneous landscapes differ by ϵ², where ϵ governs the degree of variation, suggesting that in many cases, a simpler homogeneous model gives similar spread rates. For irregular landscapes, analytical methods become intractable and numerical simulation is needed to predict spread. Accurate simulation requires high spatial resolution, which, using existing techniques, requires prohibitive amounts of computational resources (RAM, CPU etc). We overcome this by developing and implementing a novel algorithm that uses adaptive mesh refinement. The approximations and simulation algorithm produce accurate results, with the adaptive algorithm providing large improvements in efficiency without significant losses of accuracy compared to non-adaptive simulations. Hence, the adaptive algorithm enables faster simulation at previously unfeasible scales and resolutions, permitting novel areas of scientific research in species spread modelling.

Vertebrados exóticos são introduzidos intencionalmente como recurso, como uma alternativa para fins econômicos ou de lazer. Aqueles que se tornam capazes de expandir espontaneamente as novas populações em áreas naturais são conhecidas como invasores e frequentemente estão implicados em efeitos indesejados em populações, comunidades e ecossistemas autóctones. Uma destas espécies é o cervo axis Axis axis, introduzido mundialmente para a caça. Apesar da sua ampla distribuição e utilização, pouco se sabe sobre seus efeitos nas áreas invadidas e em quais regiões esta espécie pode se tornar invasora. Isto dificulta as tomadas de decisão, pois avaliar os efeitos da introdução e prever as áreas em risco de invasão são tarefas fundamentais para estratégias de prevenção, priorização e ações de controle. Assim, esse trabalho teve como objetivos revisar os efeitos do cervo axis em áreas invadidas, utilizando um protocolo de revisão sistemática, e modelar a possível distribuição mundial e regional desta espécie, utilizando variáveis bioclimáticas. Realizamos buscas por estudos sobre efeitos em áreas alóctones em três bancos de dados, utilizando três conjuntos de palavras chaves. Classificamos os estudos que atenderam aos critérios do protocolo segundo o nível de inferência sobre os efeitos em Efeito Demonstrado e Efeito Sugerido. Extraímos os tipos de efeitos relatados e a região de ocorrência. Para a modelagem de distribuição, utilizamos o algoritmo Maxent e variáveis preditoras bioclimáticas. Os pontos de ocorrência utilizados incluem sua distribuição original e três regiões onde a espécie é invasora e das quais foi possível obter ou estimar coordenadas. A revisão sistemática resultou em apenas quatro trabalhos classificados em Efeito Demonstrado, os quais apontam a competição com espécies nativas, alteração da composição florística e faunística e facilitação da entrada de outras espécies invasoras. Os efeitos sugeridos incluem seis trabalhos mostrando a ocorrência de parasitas, um caso de hibridização com outra espécie de cervídeo em cativeiro e um estudo mostrando a degradação das áreas de florestas causada pelo cervo axis em conjunto com outras espécies invasoras. O modelo de distribuição demonstra que amplas extensões da América do Sul, África Central e Sudeste Asiático são suscetíveis à invasão, portanto, nestas áreas deve-se evitar a introdução e controlar a expansão. O sul do Brasil, Uruguai, norte da Argentina e Paraguai são possíveis áreas de ocorrência segundo os modelos bioclimáticos. / Alien vertebrates are intentionally introduced for leisure and economic purposes. Those who become able to expand their populations in the new areas are known as invasive and are often involved in undesirable effects in indigenous populations, communities and ecosystems. The axis deer was introduced worldwide for hunting. Despite its wide distribution and use, little is known about its effects on the invaded areas and regions in which this species can become invasive. This complicates the decision-making because assessing the effects of the introduction and predict areas at risk of invasion are key tasks for prevention strategies, prioritization and control actions. Like this. So, this study aimed to summarize the effects of the axis deer in invaded areas using a systematic review protocol and to model the potential distribution of this species globally and in South America using bioclimatic variables. To summarized the effects we conducted searches for studies on non-native areas in three databases, using three sets of key-words and classified the studies that met the criteria of the protocol according to the level of inference about the effects they investigated. We extracted the types mentioned effects and occurrence region. To model the potential distribution based on bioclimatic variables we used the program Maxent. We used occurrences from the original distribution and three regions where the species is invasive about which geographical coordinates could be obtained or estimated. Four studies demonstrated effects of the axis deer due to competition with native species, changes in the floristic and faunistic composition and facilitation of other invasion processes. Six studies speculated the occurrence of disease transmition, hybridization with other species and difuse degradation of forest areas in combination with other invasive species. The distribution model demonstrated that large extensions of South America, Central Africa and Southeast Asia are susceptible to invasion. In the southern cone of South America Brazil, Uruguay, northern Argentina and Paraguay include extensive areas prone to invasion based on the bioclamatic models.

Biological invasions are a global threat to aquatic biodiversity. Of particular concern are invasive freshwater fishes because they have high establishment rates, and introductions can result in the displacement and extirpation of native species through a range of processes including competition and hybridization. Though it is well known that invasive freshwater fishes commonly spread following introduction events, little is known about how fast and far they may move. Additionally, observations of hybridization involving invasive stream fishes have been linked to elevated turbidity; however, the extent to which impaired water clarity influences reproductive isolation among invasive and native species remains poorly understood. To better understand how invasive freshwater fishes disperse, and how turbidity affects reproductive isolation between native and non-native species, I carried out a series of three related studies. First, I evaluated genetic variation across the native and invasive ranges of red shiner (Cyprinella lutrensis), throughout the United States. Second, I characterized genetic variation and clinal stability across a hybrid swarm involving native blacktail shiner (Cyprinella venusta stigmatura) and invasive red shiner in the Upper Coosa River Basin (UCRB), USA. Third, I examined whether turbidity influences pre-mating social interactions between invasive red shiner and native blacktail shiner. MtDNA haplotypes from native range populations of red shiner form four divergent lineages and suggest that introduced populations in the western and eastern US originate from dissimilar genetic lineages. I also recovered a previously undescribed lineage of Cyprinella that has been cryptically introduced into the western US. Examination of the hybrid swarm in the UCRB revealed that the proportion of hybrids increased between 2005 and 2011, and that the hybrid swarm is continuing to expand both upstream and downstream. Under turbid conditions, I found that pre-mating social interactions increased, and that native blacktail shiner females are especially likely to interact with invasive red shiner males. Localized control or removal may be effective in managing non-native red shiner; further monitoring, however, is needed to help identify additional factors contributing to hybrid swarm movement. Furthermore, integrating knowledge of species behavior into management planning could help deter the further establishment and spread of invasive red shiner. / acase@tulane.edu

In this dissertation I evaluated the ecological and evolutionary mechanisms that promote the spread of non-native parasites infecting novel hosts under contemporary and future climate conditions. Thorough assessment of the impact of introduced parasites and an understanding of the potential effects of climate change on parasite distributions and densities will promote effective conservation of native aquatic biodiversity. The spread of an introduced nematode parasite, Camallanus cotti, infecting the native Hawaiian stream fish, Awaous stamineus, across the Hawaiian Islands provided an opportunity to examine how biotic (densities of introduced & native hosts, individual host traits, genetic diversity) and environmental (land-use, water chemistry) factors promote novel host-parasite interactions. In addition to completing archipelago-wide surveys of parasite distributions and densities in native fish hosts, I characterized geographic patterns of genetic variation in C. cotti to assess gene flow, identify likely conduits of introduction and spread of the parasite across the archipelago. Finally, I utilized a natural precipitation gradient across the Hamakua coast on the island of Hawai`i, as a natural analog to conditions predicted by climate change, to assess the relationship between precipitation and infection of A. stamineus by C. cotti. I found the distribution C. cotti has become decoupled from that of the non-native hosts and that the parasite infects native fishes in remote, relatively pristine watersheds. The abundance, intensity, and prevalence of C. cotti infecting A. stamineus are influenced by a suite of factors, but notably parasitism increases with decreasing precipitation. This finding suggest that infection of native Hawaiian fishes by introduced parasites will increase if climate conditions change as expected. Genetic analysis indicates that C. cotti has spread across the archipelago following an initial introduction on O'ahu with subsequent dispersal to Maui and then underwent stepwise dispersal to other islands in the archipelago. Significant genetic structure also was detected across islands, suggesting that dispersal potential is constrained, which in turn suggests that remediation efforts focusing on invasion hotspots or areas of concern could be effective at reducing parasites loads in native fishes. / acase@tulane.edu