Inter- and Intraspecific Trait Compensation of Behavioural and Morphological Defences in a Damselfly Genus

Predation is a key driver of phenotypic diversification with prey having evolved sets of correlated anti-predator traits. Changes in anti-predator traits can be studied on an evolutionary as well as on a developmental timescale. Using a common garden setup, we studied inter- and intraspecific correlations of behavioural and morphological defences in four damselfly species that either occur in habitats dominated by predatory fish (fish habitats) or fishless habitats by raising larvae either with predatory fish or in a control treatment. We found inter- as well as intraspecific trait compensation (negative correlations) between behavioural and morphological defences. Compared to fishless habitat species, fish habitat species invested more in behavioural defences and less in morphological defences. This was mirrored by fish habitat species investing more in behavioural defences and less in morphological defences when reared with predatory fish whereas fishless habitat species invested less in morphological defences only. Our results emphasise the role of context-specific combinations of defensive traits to avoid predation. We suggest, considering changes in multiple correlated traits on different timescales when studying the evolution of anti-predator traits

Prior exposure of a fungal parasite to cyanobacterial extracts does not impair infection of its Daphnia host

Cyanobacteria periodically dominate phytoplankton composition in lakes, and produce a wide array of toxic secondary metabolites. Blooms of cyanobacteria often coincide with infections of zooplankton by microparasites (such as Metschnikowia bicuspidata, a parasitic yeast of Daphnia), and prior research has shown that cyanobacteria-based diets could mitigate fungal infections of the host. Here, we tested whether cyanotoxins could exert detrimental effects against free-living parasite stages: we inoculated two genotypes of the host Daphnia galeata × longispina with fungal spores, which were previously exposed to cyanobacterial extracts or to a placebo solution. Additionally, to test for interactive effects of cyanotoxins through environmental exposure and host consumption, Daphnia from each treatment were fed using either green algae or the same cyanobacterium. Exposing spores to cyanobacterial extracts did not reduce their infectivity; instead, parasite infectivity was increased, but only on one host genotype. The effect of host diet on parasite growth was also host-genotype dependent, with only one Daphnia genotype showing impaired spore production under a toxic diet. Our results suggest that dissolved cyanobacterial compounds released during blooms may not exert any detrimental effect on fungal spore banks, but likely influence transmission of the parasite when incorporated as part of the host’s diet

Love is blind: interspecific amplexus of two anuran species, the Common Toad (Bufo bufo) and the European Green Frog (Pelophylax sp.), with fire salamanders (Salamandra salamandra terrestris)

Oswald P, Schulte L, Mühlenhaupt M, Caspers B. Love is blind: interspecific amplexus of two anuran species, the Common Toad (Bufo bufo) and the European Green Frog (Pelophylax sp.), with fire salamanders (Salamandra salamandra terrestris). Herpetology Notes. 15.11.2022;(15):811-815

Prior exposure of a fungal parasite to cyanobacterial extracts does not impair infection of its Daphnia host

Manzi F, Agha R, Mühlenhaupt M, Wolinska J. Prior exposure of a fungal parasite to cyanobacterial extracts does not impair infection of its Daphnia host. Hydrobiologia. 2022.**Abstract** Cyanobacteria periodically dominate phytoplankton composition in lakes, and produce a wide array of toxic secondary metabolites. Blooms of cyanobacteria often coincide with infections of zooplankton by microparasites (such asMetschnikowia bicuspidata, a parasitic yeast ofDaphnia), and prior research has shown that cyanobacteria-based diets could mitigate fungal infections of the host. Here, we tested whether cyanotoxins could exert detrimental effects against free-living parasite stages: we inoculated two genotypes of the hostDaphnia galeata × longispinawith fungal spores, which were previously exposed to cyanobacterial extracts or to a placebo solution. Additionally, to test for interactive effects of cyanotoxins through environmental exposure and host consumption,Daphniafrom each treatment were fed using either green algae or the same cyanobacterium. Exposing spores to cyanobacterial extracts did not reduce their infectivity; instead, parasite infectivity was increased, but only on one host genotype. The effect of host diet on parasite growth was also host-genotype dependent, with only oneDaphniagenotype showing impaired spore production under a toxic diet. Our results suggest that dissolved cyanobacterial compounds released during blooms may not exert any detrimental effect on fungal spore banks, but likely influence transmission of the parasite when incorporated as part of the host’s diet

Inter- and Intraspecific Trait Compensation of Behavioural and Morphological Defences in a Damselfly Genus

Mühlenhaupt M, Jiang B, Brauner O, Mikolajewski DJ. Inter- and Intraspecific Trait Compensation of Behavioural and Morphological Defences in a Damselfly Genus. Frontiers in Ecology and Evolution. 2022;10: 874276.Predation is a key driver of phenotypic diversification with prey having evolved sets of correlated anti-predator traits. Changes in anti-predator traits can be studied on an evolutionary as well as on a developmental timescale. Using a common garden setup, we studied inter- and intraspecific correlations of behavioural and morphological defences in four damselfly species that either occur in habitats dominated by predatory fish (fish habitats) or fishless habitats by raising larvae either with predatory fish or in a control treatment. We found inter- as well as intraspecific trait compensation (negative correlations) between behavioural and morphological defences. Compared to fishless habitat species, fish habitat species invested more in behavioural defences and less in morphological defences. This was mirrored by fish habitat species investing more in behavioural defences and less in morphological defences when reared with predatory fish whereas fishless habitat species invested less in morphological defences only. Our results emphasise the role of context-specific combinations of defensive traits to avoid predation. We suggest, considering changes in multiple correlated traits on different timescales when studying the evolution of anti-predator traits

Comparability and repeatability of three commonly used methods for measuring endurance capacity

Baxter-Gilbert J, Mühlenhaupt M, Whiting MJ. Comparability and repeatability of three commonly used methods for measuring endurance capacity. Journal of Experimental Zoology Part A: Ecological and Integrative Physiology. 2017;327(10):583-591.Measures of endurance (time to exhaustion) have been used to address a wide range of questions in ecomorphological and physiological research, as well as being used as a proxy for survival and fitness. Swimming, stationary (circular) track running, and treadmill running are all commonly used methods for measuring endurance. Despite the use of these methods across a broad range of taxa, how comparable these methods are to one another, and whether they are biologically relevant, is rarely examined. We used Australian water dragons (Intellagama lesueurii), a species that is morphologically adept at climbing, swimming, and running, to compare these three methods of endurance and examined if there is repeatability within and between trial methods. We found that time to exhaustion was not highly repeatable within a method, suggesting that single measures or a mean time to exhaustion across trials are not appropriate. Furthermore, we compared mean maximal endurance times among the three methods, and found that the two running methods (i.e., stationary track and treadmill) were similar, but swimming was distinctly different, resulting in lower mean maximal endurance times. Finally, an individual's endurance rank was not repeatable across methods, suggesting that the three endurance trial methods are not providing similar information about an individual's performance capacity. Overall, these results highlight the need to carefully match a measure of performance capacity with the study species and the research questions being asked so that the methods being used are behaviorally, ecologically, and physiologically relevant

No evidence for innate differences in tadpole behavior between natural, urbanized, and invasive populations

Mühlenhaupt M, Baxter-Gilbert J, Makhubo BG, Riley JL, Measey J. No evidence for innate differences in tadpole behavior between natural, urbanized, and invasive populations. Behavioral Ecology and Sociobiology. 2022;76(1): 11.Animals are increasingly challenged to respond to novel or rapidly changing habitats due to urbanization and/or displacement outside their native range by humans. Behavioral differences, such as increased boldness (i.e., propensity for risk-taking), are often observed in animals persisting in novel environments; however, in many cases, it is unclear how these differences arise (e.g., through developmental plasticity or evolution) or when they arise (i.e., at what age or developmental stage). In the Guttural Toad (Sclerophrys gutturalis), adult urban toads from both native and invasive ranges are bolder than conspecifics in natural habitats. Here, we reared Guttural Toad tadpoles in a common garden experiment, and tested for innate differences in boldness across their development and between individuals whose parents and lineage came from rural-native, urban-native, and urban-invasive localities (i.e., origin populations). Tadpoles did not differ in their boldness or in how their boldness changed over ontogeny based on their origin populations. In general, tadpoles typically became less bold as they aged, irrespective of origin population. Our findings indicate that differences in boldness in free-living adult Guttural Toads are not innate in the tadpole stage and we discuss three possible mechanisms driving phenotypic divergence in adult boldness for the focus of future research: habitat-dependent developmental effects on tadpole behavior, decoupled evolution between the tadpole and adult stage, and/or behavioral flexibility, learning, or acclimatization during the adult stage

Stress response of fire salamander larvae differs between habitat types

Schulte L, Oswald P, Mühlenhaupt M, et al. Stress response of fire salamander larvae differs between habitat types. Bielefeld University; 2023

Growing up in a new world: trait divergence between rural, urban, and invasive populations of an amphibian urban invader

Cities are focal points of introduction for invasive species. Urban evolution might facilitate the success of invasive species in recipient urban habitats. Here we test this hypothesis by rearing tadpoles of a successful amphibian urban coloniser and invader in a common garden environment. We compared growth rate, morphological traits, swimming performance, and developmental rate of guttural toad tadpoles (Sclerophrys gutturalis) from native rural, native urban, and non-native urban habitats. By measuring these traits across ontogeny, we were also able to compare divergence across different origins as the tadpoles develop. The tadpoles of non-native urban origin showed significantly slower developmental rate (e.g., the proportion of tadpoles reaching Gosner stage 31 or higher was lower at age 40 days) than tadpoles of native urban origin. Yet, tadpoles did not differ in growth rate or any morphological or performance trait examined, and none of these traits showed divergent ontogenetic changes between tadpoles of different origin. These findings suggest that prior adaptation to urban habitats in larval traits likely does not play an important role in facilitating the invasion success of guttural toads into other urban habitats. Instead, we suggest that evolutionary changes in larval traits after colonization (e.g., developmental rate), together with decoupling of other traits and phenotypic plasticity might explain how this species succeeded in colonising extra-limital urban habitats