On a global scale, species are constantly being moved from their areas of origin to new locales. Such range extensions can occur naturally, but are frequently aided (intentionally or non-intentionally) by humans (Mack <em>et al.</em> 2000). As a result, the marked world-wide increase in animal, plant, and microbial immigrations, has been found to roughly track the increase in human commerce (Mack <em>et al.</em> 2000). The principal vectors of human-mediated marine invasions are ballast water (Williams <em>et al.</em> 1988), mariculture (Minchin 1996), sediment held in ballast tanks (Carlton 1985), and ship hull fouling (Minchin 1996)

No abstract

Environmental temperature variation generates adaptive phenotypic differentiation in widespread populations. We used a common garden experiment to determine whether offspring with varying parental origins display adaptive phenotypic variation related to different thermal conditions experienced in parental environments. We compared burst swimming performance and critical thermal limits of African clawed frog (Xenopus laevis) tadpoles bred from adults captured at high (∼ 2000 m above sea level) and low (∼ 5 m above sea level) altitudes. Maternal origin significantly affected swimming performance. Optimal swimming performance temperature had a >9°C difference between tadpoles with low altitude maternal origins (Topt: pure- and cross-bred 35.0°C) and high altitude maternal origins (Topt: pure-bred 25.5°C, cross-bred 25.9°C). Parental origin significantly affected critical thermal limits. Pure-bred tadpoles with low altitude parental origins had higher CTmax (37.8±0.8°C) than pure-bred tadpoles with high altitude parental origins and all cross-bred tadpoles (37.0±0.8 and 37.1±0.8°C). Pure-bred tadpoles with low altitude parental origins and all cross-bred tadpoles had higher CTmin (4.2±0.7 and 4.2±0.7°C) than pure-bred tadpoles with high altitude parental origins (2.5±0.6°C). Our study shows Xenopus laevis tadpoles’ varying thermal physiological traits is the result of adaptive responses to their parental thermal environments. This study is one of few demonstrating potential intraspecific evolution of critical thermal limits in a vertebrate species. Multi-generation common garden experiments and genetic analyses would be required to further tease apart the relative contribution of plastic and genetic effects to the adaptive phenotypic variation observed in these tadpoles.

This review provides the first assessment of animal species that are native to South Africa and invasive elsewhere in the world. While around a twelfth of all naturalised plants in the world are native to South Africa, there are very few examples of South African native marine, terrestrial, or freshwater animals becoming invasive elsewhere. We provide a narrative of each of the 34 cases that we could find. Three of these species, the Common Waxbill, Estrilda astrild, the Mozambique Tilapia, Oreochromis mossambicus and the African Clawed Frog, Xenopus laevis, were widely traded, and introduced on several continents with invasive populations becoming the subject of substantial research. Most other species are poorly documented in the literature such that it is often not known whether South African populations are the source of invasions. These species demonstrate the same trend in pathways of animals entering South Africa, moving from deliberate to accidental through time. The role of mavericks, individuals whose deliberate actions wilfully facilitate invasions, is highlighted. While South Africa has acted as an important bridgehead for the invasions of forestry pests, crayfish, fish and amphibians on the continent, it is clearly not a major donor of animal invasions, but rather a recipient. This could be due to South African ecosystems being fundamentally more invasible, or South African fauna showing reduced invasiveness, though it is likely that substantial differences in historical pathways also played a crucial role.

Phenotypic variation in Xenopus laevis tadpoles from contrasting climatic regimes is the result of adaptation and plasticity. file:///C:/Users/kruge/Desktop/Paper/Oecologia-paper.html 2/43 install.packages("DHARMa") ## Installing package into 'C:/Users/kruge/AppData/Local/R/win-library/4.2' ## (as 'lib' is unspecified) install.packages("survival") ## Installing package into 'C:/Users/kruge/AppData/Local/R/win-library/4.2' ## (as 'lib' is unspecified) install.packages("coxme") ## Installing package into 'C:/Users/kruge/AppData/Local/R/win-library/4.2' ## (as 'lib' is unspecified) install.packages ("performance") ## Installing package into 'C:/Users/kruge/AppData/Local/R/win-library/4.2' ## (as 'lib' is unspecified)

In amphibians, spatial sorting progressively enhances the dispersal capacities of dispersing stages in expanding populations but may enhance or limit the performance of the earlier non-dispersing stages. Phenotypic traits of non-dispersing tadpoles and metamorphs can be coupled, through carry-over effects and trade-offs, or decoupled to dispersal traits in adults. We used the globally invasive amphibian, Xenopus laevis, to examine whether spatial sorting of adult phenotypes affects the phenotype of larval stages to metamorphosis in the core and at the periphery of an invasive population in France. We combined common garden laboratory and outdoor experiments to test the effect of parental pond location (core or periphery) on morphology, development and survival to metamorphosis and found no differences between tadpoles. After metamorphosis, the only difference observed in either of the experiments was the larger body size of metamorphs from the periphery, and then only when reared in the laboratory. Differences in metamorph size may indicate that a shift of dispersal traits occur after metamorphosis in X. laevis. Thus, our findings illustrate that decoupled evolution through spatial sorting can lead to changes of X. laevis adult phenotypes that would enhance dispersal without affecting the phenotype of tadpoles before metamorphosis.

No abstract

HighlightsUnique leech in that it keeps it young inside a brood pouch, hence its name.This leech is quite rare and only known from three localities.First paper to show SEM pictures of Marsupiobdella spermatophore.New info on its reproductive behavior.