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opencc-zeroJan 2020View details →

Neonicotinoid and sulfoximine pesticides differentially impair insect escape behaviour and motion detection

Insect nervous systems offer unique advantages for studying interactions between sensory systems and behaviour given that they are complex and yet highly tractable. By examining the neural coding of salient environmental stimuli and resulting behavioural output in the context of environmental stressors, we gain an understanding of the effects of these stressors on brain and behaviour and provide insight into normal function. The implication of neonicotinoid (neonic) pesticides in contributing to declines of non-target species, such as bees, has motivated development of new compounds, which could potentially mitigate putative resistance in target species (1, 2) and declines of non-target species. We used a neuroethological approach, including behavioural assays and multineuronal recording techniques, to investigate effects of imidacloprid and the novel insecticide sulfoxaflor on visual motion-detection circuits and related escape behaviour in the tractable locust system. Despite similar LD50 values, imidacloprid and sulfoxaflor evoked different behavioural and physiological effects. Imidacloprid significantly attenuated collision avoidance behaviours and impaired responses of neural populations, including a decrease in spontaneous firing and decreased neural habituation. In contrast, sulfoxaflor displayed no effect at a comparable sublethal dose. These are the first results to show that a neonic affects population responses and habituation of a visual motion detection system. We propose that differences in the sublethal effects of sulfoxaflor reflect an altered mode of action to imidacloprid. More broadly, we suggest that neuroethological assays for comparative neurotoxicology are a valuable tool to fully address current issues regarding proximal effects of environmental toxicity in non-target species.

opencc-zeroDec 2013View details →

Data from: Spatial and temporal escape from fungal parasitism in natural communities of anciently asexual bdelloid rotifers

Sexual reproduction is costly, but it is nearly ubiquitous among plants and animals, whereas obligately asexual taxa are rare and almost always short-lived. The Red Queen hypothesis proposes that sex overcomes its costs by enabling organisms to keep pace with coevolving parasites and pathogens. If so, the few cases of stable long-term asexuality ought to be found in groups whose coevolutionary interactions with parasites are unusually weak. In theory, antagonistic coevolution will be attenuated if hosts disperse among patches within a metapopulation separately from parasites and more rapidly. We examined whether these conditions are met in natural communities of bdelloid rotifers, one of the longest-lived asexual lineages. At any life stage, these microscopic invertebrates can tolerate the complete desiccation of their ephemeral freshwater habitats, surviving as dormant propagules that are readily carried by the wind. In our field experiments, desiccation and wind transport enabled bdelloids to disperse independently of multiple fungal parasites, in both time and space. Surveys of bdelloid communities in unmanipulated moss patches confirmed that fungal parasitism was negatively correlated with extended drought and increasing height (exposure to wind). Bdelloid ecology therefore matches a key condition of models in which asexuals persist through spatio-temporal decoupling from coevolving enemies.

opencc-zeroDec 2017View details →

Data from: Estimating the relative fitness of escaped farmed salmon offspring in the wild and modeling the consequences of invasion for wild populations

Throughout their native range, wild Atlantic salmon populations are threatened by hybridization and introgression with escapees from net-pen salmon aquaculture. Although domestic-wild hybrid offspring have shown reduced fitness in lab and field experiments, consequential impacts on population abundance and genetic integrity remain difficult to predict in the field, in part because the strength of selection against domestic offspring is often unknown and context-dependent. Here we follow a single large escape event of farmed Atlantic salmon in southern Newfoundland and monitor changes in the in-river proportions of hybrids and feral individuals over time using genetically-based hybrid identification. Over a three-year period following the escape, the overall proportion of wild parr increased consistently (total wild proportion of 71.6%, 75.1%, 87.5% each year, respectively), with subsequent declines in feral (genetically pure farmed individuals originating from escaped, farmed adults) and hybrid parr. We quantify the strength of selection against parr of aquaculture ancestry and explore the genetic and demographic consequences for populations in the region. Within-cohort changes in the relative proportions of feral and F1 parr suggest reduced relative survival compared to wild individuals over the first (0.15 and 0.81 for feral and F1, respectively), and second years of life (0.26, 0.83). These relative survivorship estimates were used to inform an individual-based salmon eco-genetic model to project changes in adult abundance and overall allele frequency across three invasion scenarios ranging from short-term to long-term invasion and three relative survival scenarios. Modeling results indicate that total population abundance and time to recovery were greatly affected by relative survivorship and predict significant declines in wild population abundance under continued large escape events and calculated survivorship. Overall this work demonstrates the importance of estimating the strength of selection against domestic offspring in the wild to predict the long-term impact of farmed salmon escape events on wild populations.

opencc-zeroDec 2017View details →

Data from: Cleaner fish escape salmon farms and hybridize with local wrasse populations

The genetic impact of farmed fish escaping aquaculture is a highly debated issue. However, non-target species, such as cleaner fish used to remove sea lice from farmed fish, are rarely considered. Here we report that wild corkwing wrasse (Symphodus melops), which are transported long distances to be used as cleaner fish in salmon farms, escape and hybridize with local populations. Recently, increasing numbers of corkwing wrasse have been reported in Flatanger in Norway, north of its described distribution range, an area heavily relying on import of cleaner fish from Skagerrak. Using genetic markers identified with 2bRAD sequencing, we show that, although the Flatanger population largely is a result of a northwards range expansion, there is also evidence of considerable gene flow from southern populations in Skagerrak and Kattegat. Out of 40 corkwing wrasses sampled in Flatanger, we discovered two individuals with clear southern genotypes, one first generation hybrid, and twelve potential second-generation hybrids. In summary, we provide evidence that corkwing wrasse escape from fish farms and hybridize with local populations at the leading edge of an ongoing range expansion. Although the magnitude and significance of escapees warrants further investigation, these results should be taken in consideration in the use of translocated cleaner fish.

opencc-zeroDec 2011View details →

Data from: Nest predation risk and growth strategies of passerine species: grow fast or develop traits to escape risk?

Different body components are thought to trade off in their growth and development rates, but the causes for relative prioritization of any trait remains a critical question. Offspring of species at higher risk of predation might prioritize development of locomotor traits that facilitate escaping risky environments over growth of mass. We tested this possibility in 12 altricial passerine species that differed in their risk of nest predation. We found that rates of growth and development of mass, wings, and endothermy increased with nest predation risk across species. In particular, species with higher nest predation risk exhibited relatively faster growth of wings than of mass, fledged with relatively larger wing sizes and smaller mass, and developed endothermy earlier at relatively smaller mass. This differential development can facilitate both escape from predators and survival outside of the nest environment. Tarsus growth was not differentially prioritized with respect to nest predation risk, and instead all species achieved adult tarsus size by age of fledging. We also tested whether different foraging modes (aerial, arboreal, and ground foragers) might explain the variation of differential growth of locomotor modules, but we found that little residual variation was explained. Our results suggest that differences in nest predation risk among species are associated with relative prioritization of body components to facilitate escape from the risky nest environment.

opencc-zeroDec 2014View details →

Data from: Escape of spring frost and disease through phenological variations in oak populations along elevation gradients

1. The timing of tree flushing follows strong phenotypic and genetic clines across environmental gradients. It may be seen as an adaptive response to abiotic (escape of spring frost and maximizing growing season length) and biotic (escape of pest and disease) hazards. However, few studies have investigated jointly both types of hazards. 2. We assessed exposure to both abiotic (spring frost) and biotic (powdery mildew) hazards within and between sessile oak populations along elevation gradients, during the flushing period in several years. For each population and phenological phenotype (early- vs. late-flushing trees), we estimated safety margins, defined as the time period separating budburst from the hazard occurrence (spore emission, spring frost). 3. We observed that powdery mildew phenology (initiation of spore release in spring) was less responsive to the elevation gradient than oak phenology (budburst) and that it was not correlated with tree phenology within populations. The spring frost and disease safety margins varied considerably between oak populations as a function of elevation and within populations in relation to tree phenological phenotype. For both hazards, safety margins decreased significantly with increasing elevation. The safety margin for spring frost was mostly positive (i.e. escape), whereas the safety margin for powdery mildew was mostly negative (i.e. exposure), leading to infection. The abiotic and biotic hazards interact in opposite directions with phenology, especially at low elevations (< 500 m) where early flushing enabled trees to escape disease while late flushing provided a higher safety margin against late frost. 4. Synthesis. The observed patterns suggest that oak populations are better adapted to escape spring frost than pathogen exposure all along the elevation gradient. The combination of the biotic and abiotic selective pressures may have contributed to the maintenance of phenological diversity within low-elevation tree populations. As tree and pathogen respond differently to environmental cues, climate change is likely to affect the phenological (a)synchrony between host and parasite, both within and between populations.

opencc-zeroDec 2017View details →

Data from: Interacting effects of predation risk and resource level on escape speed of amphibian larvae along a latitudinal gradient

Fast-growing genotypes living in time-constrained environments are often more prone to predation, suggesting that growth-predation risk trade-offs are important factors maintaining variation in growth along climatic gradients. However, the mechanisms underlying how fast growth increases predation-mediated mortality are not well understood. Here, we investigated if slow-growing, low-latitude individuals have faster escape swimming speed than fast-growing high-latitude individuals using common frog (Rana temporaria) tadpoles from eight populations collected along a 1500 km latitudinal gradient. We measured escape speed in terms of burst and endurance speeds in tadpoles raised in the laboratory at two food levels and in the presence and absence of a predator (Aeshna dragonfly larvae). We did not find any latitudinal trend in escape speed performance. In low food treatments, burst speed was higher in tadpoles reared with predators but did not differ between high food treatments. Endurance speed, on the contrary, was lower in high-food tadpoles reared with predators, and did not differ between treatments at low food levels. Tadpoles reared with predators showed inducible morphology (increased relative body size and tail depth), which had positive effects on speed endurance at low but not at high food levels. Burst speed was positively affected by tail length and tail muscle size in the absence of predators. Our results suggest that escape speed does not trade off with fast growth along the latitudinal gradient in R. temporaria tadpoles. Instead, escape speed is a plastic trait and strongly influenced by the interaction between resource level and predation risk.

opencc-zeroDec 2010View details →

Data from: Winning the invasion roulette: escapes from fish farms increase admixture and facilitate establishment of non-native rainbow trout

Aquaculture is a major source of invasive aquatic species, despite the fact that cultured organisms often have low genetic diversity and tend to be maladapted to survive in the wild. Yet, to what extent aquaculture escapees become established by means of high propagule pressure and multiple origins is not clear. We analysed the genetic diversity of 15 established populations and 4 farmed stocks of non-native rainbow trout in Chile, a species first introduced for recreational fishing around 1900, but which has in recent decades escaped in large numbers from fish farms and become widespread. Aquaculture propagule pressure was a good predictor of the incidence of farm escapees, which represented 16% of all free-ranging rainbow trout and were present in 80% of the study rivers. Hybrids between farm escapes and established trout were present in all rivers at frequencies ranging between 7 and 69%, and population admixture was positively correlated with genetic diversity. We suggest that non-native salmonids introduced into the Southern Hemisphere could benefit from admixture because local adaptations may not have yet developed and there may be initially little fitness loss resulting from outbreeding depression.

opencc-zeroDec 2016View details →

Data from: Gene flow from domesticated escapes alters the life history of wild Atlantic salmon

Interbreeding between domesticated and wild animals occurs in several species. This gene flow has long been anticipated to induce genetic changes in life-history traits of wild populations, thereby influencing population dynamics and viability. Here, we show that individuals with high levels of introgression (domesticated ancestry) have altered age and size at maturation in 62 wild Atlantic salmon Salmo salar populations, including seven ancestral populations to breeding lines of the domesticated salmon. This study documents widespread changes to life-history traits in wild animal populations following gene flow from selectively bred, domesticated conspecifics. The continued high abundance of escaped, domesticated Atlantic salmon thus threatens wild Atlantic salmon populations by inducing genetic changes in fitness-related traits. Our results represent key evidence and a timely warning concerning the potential ecological impacts of the globally increasing use of domesticated animals.

opencc-zeroDec 2016View details →

Data from: Seed dispersers help plants to escape global warming

Plants are shifting their ranges towards higher elevations in response to global warming, yet such shifts are occurring at a rate slower than is needed to keep pace with a rapidly changing climate. There is, however, an almost complete lack of knowledge on seed dispersal across altitude, a key process to understand what constrains climate-driven range shifts. Here, we report the first direct empirical evidence on altitudinal seed dispersal mediated by two common frugivorous mammals: the red fox Vulpes vulpes and the pine marten Martes martes. We conducted a three-year (bait-marking) experiment in a mountainous region of Spain. We offered experimental fruits containing colour-coded seed mimics at feeding stations that simulated source trees. The colour codes allowed us to identify the exact origin of seed mimics found later in mammal scats. Nearly half (47%) of the dispersal events occurred towards higher elevations, despite only ca 25% of the study area being above the average altitude of the feeding stations (1344 m). Seeds dispersed uphill gained an average of 106 m (median = 111 m) and a maximum of 288 m, greatly exceeding the estimated requirements to escape warming (35.4 m per decade). Yet, foxes mediated much more uphill seed dispersal than martens (57% and 26% of dispersal events, respectively), which can be explained by between-disperser differences in home range size and habitat specificity. Dispersers with larger home ranges move farther and potentially disperse more seeds to higher altitudes, while habitat generalism is necessary to transport seeds above vegetation belts delimiting contrasting habitat types. We discuss how both traits (home range size and habitat specificity) can be used to infer altitudinal seed dispersal across disperser species and mountainous landscapes.

opencc-zeroJun 2021View details →

The anti-predation benefit of flash displays is related to the distance at which the prey initiates its escape

Flash behaviour is widespread in the animal kingdom and describes the exposure of a hidden conspicuous signal by an otherwise cryptic individual as it is fleeing from predators. Recent studies have demonstrated that the signal can enhance survivorship by leading pursuing predators into believing the flasher will also be conspicuous at rest. Naturally, this illusion will work best if potential predators are ignorant of the flasher's resting appearance. One way in which this could be achieved is by the prey fleeing when the predator is far away. To test this hypothesis, we compared the survival of flashing and non-flashing computer-generated prey with different flight initiation distances (FIDs) using humans as model predators. This experiment found that flash displays confer a significant survivorship advantage only to those prey with a sufficiently long FID that the predator has little opportunity to view them at rest. A complementary phylogenetic analysis of Australian bird species supports these results: after controlling for body size, species with putative flashing signals had longer FIDs than those without. Species with putative flashing signals also tended to be larger, as demonstrated in other taxa. The anti-predation benefit of flash displays is therefore related to the nature of escape behaviour.

opencc-zeroDec 2014View details →

Data from: Escaping peril: perceived predation risk affects migratory propensity

Although migratory plasticity is increasingly documented, the ecological drivers of plasticity are not well understood. Predation risk can influence migratory dynamics, but whether seasonal migrants can adjust their migratory behaviour according to perceived risk is unknown. We used electronic tags to record the migration of individual roach (Rutilus rutilus), a partially migratory fish, in the wild following exposure to manipulation of direct (predator presence/absence) and indirect (high/low roach density) perceived predation risk in experimental mesocosms. Following exposure, we released fish in their lake summer habitat and monitored individual migration to connected streams over an entire season. Individuals exposed to increased perceived direct predation risk (i.e. a live predator) showed a higher migratory propensity but no change in migratory timing, while indirect risk (i.e. roach density) affected timing but not propensity showing that elevated risk carried over to alter migratory behaviour in the wild. Our key finding demonstrates predator-driven migratory plasticity, highlighting the powerful role of predation risk for migratory decision-making and dynamics.

opencc-zeroDec 2012View details →

Data from: Influence of gaze and directness of approach on the escape responses of the Indian rock lizard, Psammophilus dorsalis (Gray, 1831)

Animals often evaluate the degree of risk posed by a predator and respond accordingly. Since many predators orient their eyes towards prey while attacking, predator gaze and directness of approach could serve as conspicuous indicators of risk to prey. The ability to perceive these cues and discriminate between high and low predation risk should benefit prey species through both higher survival and decreased energy expenditure. We experimentally examined whether Indian rock lizards (Psammophilus dorsalis) can perceive these two indicators of predation risk by measuring the variation in their fleeing behaviour in response to type of gaze and approach by a human predator. Overall, we found that the gaze and approach of the predator influenced flight initiation distance, which also varied with attributes of the prey (i.e. size/sex and tail-raise behaviour). Flight initiation distance (FID) was 43% longer during direct approaches with direct gaze compared with tangential approaches with averted gaze. In further, exploratory, analyses, we found that FID was 23% shorter for adult male lizards than for female or young male (FYM) lizards. In addition, FYM lizards that showed a tail-raise display during approach had a 71% longer FID than those that did not. Our results suggest that multiple factors influence the decision to flee in animals. Further studies are needed to test the generality of these factors and to investigate the proximate mechanisms underlying flight decisions.

opencc-zeroDec 2018View details →

Data from: Contagious fear: escape behaviour increases with flock size in European gregarious birds

Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator-prey interactions. Among the factors affecting FID, tests of effects of group size (i.e. number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e. the dilution effect caused by the presence of many individuals) or positively (i.e. increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than non-gregarious species. Sociality may explain why earlier findings on group size vs. FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer flight initiation distance) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of anti-predator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species.

FIGURE 7. Aloe mitriformis, a in An annotated catalogue of Aloe and Aloiampelos (Asphodelaceae subfam. Alooideae) naturalised and escaped in continental Portugal

FIGURE 7. Aloe mitriformis, a distinctive, South African representative of the genus, has long, creeping stems. It occurs naturally in the western parts of the Western Cape province and southern Northern Cape province, an area that experiences a Mediterranean-type climate, i.e., mild, wet winters and hot, dry summers, not unlike that prevalent over much of Portugal. Photograph: Gideon F. Smith.

FIGURE 6 in An annotated catalogue of Aloe and Aloiampelos (Asphodelaceae subfam. Alooideae) naturalised and escaped in continental Portugal

FIGURE 6. Aloiampelos ciliaris in Portugal. A. A dense planting in the Botanical Garden of the University of Lisbon (see Smith & Figueiredo 2016). Photograph taken on 2 January 2013. B. Grown in a garden at Casa Mata, Malveira Serra, near Lisbon. Photograph taken on 29 April 2017. C. Close-up of the distinctly ciliate leaf bases. D. Inflorescences are usually unbranched, but could rarely be oncebranched. All photographs by Gideon F. Smith, except B, which was taken by Vasco Silva.

FIGURE 5 in An annotated catalogue of Aloe and Aloiampelos (Asphodelaceae subfam. Alooideae) naturalised and escaped in continental Portugal

FIGURE 5. Aloe vera in Portugal. A. Potted specimens of A. vera (plant on the left) and A. ×nobilis (plant on the right) grown on a windowsill in Caldas da Rainha, Estremadura. Especially A. vera is often kept near a kitchen with its leaf juices used to treat minor burns and skin abrasions. Photograph taken on 11 September 2011. B. Grown in a large plant container on the stoep of a house near the town centre in Golega, in the centre of the country. Photograph taken on 17 January 2018. C. A branched inflorescence. D. Close-up of flowers and buds. All photographs by Gideon F. Smith.

FIGURE 1 in An annotated catalogue of Aloe and Aloiampelos (Asphodelaceae subfam. Alooideae) naturalised and escaped in continental Portugal

FIGURE 1. Aloe arborescens in Portugal. A. Cultivated in beds next to the Estufa Fria, Lisbon. Photograph taken on 30 December 2013. B. Cultivated near the old town centre of Coimbra, en route to the University of Coimbra. Photograph taken on 8 January 2018. C. Cultivated in the Botanical Garden of the University of Porto. Photograph taken on 22 December 2017 (see Smith & Figueiredo 2014). D. Escaped into natural vegetation at Nazaré, Estremadura (see Smith & Figueiredo 2009). Photograph taken on 4 October 2008. E. Naturalised at Praia da Ilha Pessegueiro, along the Alentejo Litoral coast, near Porto Covo. Photograph taken on 30 December 2017. F. Naturalised at Porto Covo. Photograph taken on 30 December 2017. All photographs by Gideon F. Smith.

FIGURE 2 in An annotated catalogue of Aloe and Aloiampelos (Asphodelaceae subfam. Alooideae) naturalised and escaped in continental Portugal

FIGURE 2. Aloe maculata in Portugal. A. Naturalised at Almograve along the Baixo Alentejo coast. Photograph taken on 29 December 2017. B. Naturalised at Porto Covo along the Alentejo Litoral coast. Photograph taken on 30 December 2017. C. Naturalised at Malveira da Serra, Almoinhas Velhas, in Cascais, near metropolitan Lisbon. Photograph taken on 28 September 2014. D. Close-up of an inflorescence that carries salmon-orange flowers. The racemes are distinctly capitate and flowers have prominent basal swellings. All photographs by Gideon F. Smith.

FIGURE 3 in An annotated catalogue of Aloe and Aloiampelos (Asphodelaceae subfam. Alooideae) naturalised and escaped in continental Portugal

FIGURE 3. Two nothospecies with which Aloe maculata can be confused. A. Aloe ×schimperi [A. maculata × A. striata] cultivated in the Botanical Garden of the University of Porto, Porto. Note the distinctly pinkish leaf margins, a character inherited from A. striata. B. The flowers of A. ×schimperi lack the prominent basal swellings present in A. maculata. Both photographs A and B were taken on 22 December 2017. C. The rosettes of A. ×commutata [A. grandidentata × A. maculata] resemble those of A. maculata, but, as shown in D, its inflorescences are elongated (not capitate) and the flowers of this nothospecies, too, lack basal swellings, as found in A. grandidentata. Both photographs C and D were taken in the Huntington Botanical Gardens, San Marino, California, U.S.A., on 27 April 2011. All photographs by Gideon F. Smith.