Eastern mosquitofish (Gambusia holbrooki) are among the most widely introduced freshwater species globally. To gain a better understanding of feeding patterns in non‐native populations, and which ...local factors may influence them at the population level, we carried out gut content analysis on 163 specimens from nine invasive populations in Italy and Spain. Based on previous studies, we predicted that (a) mosquitofish are omnivores with a preference for detritus and cladocerans; (b) they display size‐ and population‐specific differences in gut morphologies and diet, with larger fish feeding more intensively over a wider range of prey items; and (c) some of the variation would be associated with differences in local environmental and climatic factors. Our results confirmed our first prediction, because mosquitofish fed on a variety of diet items, among which detritus and Cladocera dominated. However, not a single diet item was shared among all populations. Congruent with our second prediction, we further identified size‐ and population‐specific differences in the occurrence of some diet items and gut morphologies. However, observed patterns in dietary habits did not seem to be driven by the environmental and climatic variables we had quantified. The fairly variable diet likely aids invasion success and helps explain the ubiquity of invasive mosquitofish across Italy and Spain, as mosquitofish seem to be able to rely on whatever a local habitat provides. We further propose that size‐specific differences likely capture the substantial sexual size dimorphism (males are smaller than females), while population‐specific differences are likely the result of differences in local prey abundance. The lack of an influence of temperature on dietary habits suggests that mosquitofish feeding ecology may be less impacted by rising temperatures than other freshwater fish species. If true, then this suggests climate change‐induced effects may further exacerbate the competitive superiority of mosquitofish over native species in the future.
A comparison between 9 invasive populations of eastern mosquitofish across Italy and Spain found strong size‐specific differences in feeding patterns that are probably linked to sexual dimorphism (males are smaller than females). Moreover, mosquitofish fed on a wide array of prey, yet no single diet item/category was shared among all populations. This feeding flexibility could help facilitate their invasion success.
In this contribution, new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, confirmations, and exclusions to the Italian administrative ...regions. New combinations in the genera
Pilosella
and
Roemeria
are proposed. Furthermore, the name
Papaver siculum
is lectotypified. Nomenclatural and distribution updates, published elsewhere, and corrigenda are provided as Suppl. material 1.
In this contribution, new data concerning bryophytes, fungi and lichens of the Italian flora are presented. It includes new records and confirmations for the algal genus
Chara
, for the bryophyte ...genera
Bryum
,
Grimmia
,
Cephaloziella
,
Hypnum
,
Nogopterium
,
Physcomitrium
,
Polytrichastrum
,
Rhynchostegiella
,
Saelania
, and
Schistostega
, the fungal genera
Cortinarius
,
Lentinellus
,
Omphalina
, and
Xerophorus
, and the lichen genera
Acarospora
,
Agonimia
,
Candelariella
,
Cladonia
,
Graphis
,
Gyalolechia
,
Hypogymnia
,
Lichinella
,
Megalaria
,
Nephroma
,
Ochrolechia
,
Opegrapha
,
Peltigera
,
Placidium
,
Ramalina
,
Rhizoplaca
,
Ropalospora
,
Strangospora
,
Toniniopsis
,
Usnea
, and
Zahlbrucknerella
.
In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions for Italy or for Italian administrative ...regions. Nomenclatural and distribution updates, published elsewhere, and corrections are provided as Suppl. material 1.
One century after their introduction to Europe, eastern mosquitofish (Gambusia holbrooki) represent a natural experiment to determine the relative contributions of adaptive plasticity and rapid ...evolutionary change in creating large-scale geographic variation in phenotypes. We evaluated the population-genetic structure and invasion history based on allele length polymorphisms of 15 nuclear microsatellites, which we quantified for N = 660 individuals from 23 populations sampled in 2013 across the invasive range of G. holbrooki in Europe. We analysed body-shape and life-history variation in N = 1331 individuals from 36 populations, sampled in 2013 and 2017, and tested heritability of phenotypic differences in a subset of four populations using a common-garden experiment. The genetic structure of wild-caught individuals suggested a single introduction for all European mosquitofish, which were genetically impoverished compared to their native counterparts. We found some convergent patterns of phenotypic divergence across native and invasive climatic gradients (e.g., increased body size in colder/more northern populations); however, several phenotypic responses were not consistent between sampling years, pointing towards plastic phenotypes. Our analysis of common-garden reared individuals uncovered moderate heritability estimates only for two measures of male body size (intraclass correlation coefficient, ICC = 0.628 and 0.556) and offspring fat content (ICC = 0.734), while suggesting high levels of plasticity in most other phenotypic traits (ICC ≤ 0.407). Our results highlight the importance of phenotypic plasticity in invasive species during range expansions and demonstrate that strong selective pressures—in this case towards increased body size in colder environments—simultaneously promote rapid evolutionary divergence.
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•Mosquitofish (Gambusia holbrooki) invaded Europe < 100 years ago.•Population genetics suggest a single introduction from the same source population.•Climate shapes phenotypic diversification across their European invasive range.•Common-garden rearing suggests a minor contribution of genetic evolution.•Plasticity of morphological and life-history responses was largely maintained.
Pollution damages ecosystems around the globe and some forms of pollution, like oil pollution, can be either man-made or derived from natural sources. Despite the pervasiveness of oil pollution, ...certain organisms are able to colonise polluted or toxic environments, yet we only have a limited understanding of how they are affected by it. Here, we analysed phenotypic responses to oil pollution in guppies (Poecilia reticulata) living in oil-polluted habitats across southern Trinidad. We analysed body-shape and life-history traits for 352 individuals from 11 independent populations, six living in oil-polluted environments (including the naturally oil-polluted Pitch Lake), and five stemming from non-polluted habitats. Based on theory of, and previous studies on, responses to environmental stressors, we predicted guppies from oil-polluted waters to have larger heads and shallower bodies, to be smaller, to invest more into reproduction, and to produce more but smaller offspring compared to guppies from non-polluted habitats. Contrary to most of our predictions, we uncovered strong population-specific variation regardless of the presence of oil pollution. Moreover, guppies from oil-polluted habitats were characterised by increased body size; rounder, deeper bodies with increased head size; and increased offspring size, when compared to their counterparts from non-polluted sites. This suggests that guppies in oil-polluted environments are not only subject to the direct negative effects of oil pollution, but might gain some (indirect) benefits from other concomitant environmental factors, such as reduced predation and reduced parasite load. Our results extend our knowledge of organismal responses to oil pollution and highlight the importance of anthropogenic pollution as a source of environmental variation. They also emphasise the understudied ecological heterogeneity of extreme environments.
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•Crude-oil pollution negatively impacts (aquatic) ecosystems worldwide.•Guppies have colonised several oil-polluted habitats in southern Trinidad.•We found limited evidence for negative effects of oil pollution on guppy phenotypes.•Guppy phenotypes instead suggest positive, indirect effects of pollution.•Some species might be able to exploit polluted environments to their advantage.
Several factors are involved in determining the outcome of sperm competition. In addition to sperm number, sperm quality and male phenotype, insemination order is often associated with skewed ...paternity share. Patterns of sperm precedence can be produced by the mechanics of sperm storage and fertilization, or by active processes under male or female control. However, as males and females always interact during copulation, it is difficult to identify the mechanism responsible. The Trinidadian guppy, Poecilia reticulata, is a polyandric species characterized by last-male sperm precedence in natural matings. During such matings, females allow attractive males to inseminate more sperm by controlling copulation duration. We used artificial insemination to clarify the extent to which female control of sperm transfer influences the observed pattern of sperm precedence in this species. This technique allowed us to experimentally manipulate the number of sperm transferred and the timing of insemination. We found a significant first-male fertilization advantage. This advantage, however, declined as the time between insemination and parturition increased. Presumably, the anatomy and the physiology of the female genital tract favour egg fertilization by the first ejaculate inseminated, whereas sperm mixing is likely to be responsible for the reduction in first-male advantage associated with longer insemination–parturition intervals. Our results suggest that the last-male precedence detected after two consecutive natural matings is caused by cryptic female preference for attractive males associated with a female trading-up strategy (i.e. the second male is more frequently more attractive than the first male), rather than by insemination order per se. As the pattern of sperm precedence has important consequences for male reproductive strategies (for example mate guarding and male mate choice copying), unravelling its dynamic represents an important contribution to understanding the sexual behaviour of this model species.
•Insemination order affects the outcome of sperm competition.•Artificial insemination highlights first-male sperm precedence.•The mechanics of storage and fertilization are likely to be responsible for FMP.•FMP is reduced as insemination-parturition interval increases.•Last-male precedence in natural matings is produced by female-mediated processes.
Multiple paternity (MP) increases offspring's genetic variability, which could be linked to invasive species' evolvability in novel distribution ranges. Shifts in MP can be adaptive, with greater MP ...in harsher/colder environments or towards the end of the reproductive season, but climate could also affect MP indirectly via its effect on reproductive life histories. We tested these hypotheses by genotyping N = 2,903 offspring from N = 306 broods of two closely related livebearing fishes, Gambusia holbrooki and Gambusia affinis. We sampled pregnant females across latitudinal gradients in their invasive ranges in Europe and China, and found more sires per brood and a greater reproductive skew towards northern sampling sites. Moreover, examining monthly sampling from two G. affinis populations, we found MP rates to vary across the reproductive season in a northern Chinese, but not in a southern Chinese population. While our results confirm an increase of MP in harsher/more unpredictable environments, path analysis indicated that, in both cases, the effects of climate are likely to be indirect, mediated by altered life histories. In both species, which rank amongst the 100 most invasive species worldwide, higher MP at the northern edge of their distribution probably increases their invasive potential and favours range expansions, especially in light of the predicted temperature increases due to global climate changes.
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