Experimental Ecology

Intraspecific genotypic richness and relatedness predict the invasibility of microbial communities

by Alexandre Jousset

Experimental Test of Intraspecific Competition Mechanisms Among Tadpoles of Leptodactylus ocellatus (Anura: Leptodactylidae)

by Raul Maneyro

Le premier millet en France : récolte et mouture suivant l'archéologie et l'expérimentation

by Bertrand Poissonnier

published in 'Grazer Beiträge zur Europäischen Ethnologie, 4, 1995, 63-70. Publications of the Sympozion at Aizenay, August 18-19, 1990.

Early Panicum miliaceum in France: gathering and pouding according to Archaeology and experiment. Early Panicum miliaceum in France: gathering and pouding according to Archaeology and experiment.

Nitrogen fluxes from treefrogs to tank epiphytic bromeliads: an isotopic and physiological approach

by Fausto Nomura

Co-authored with Gustavo Q. Romero, Ana Z. Gonçalves,
Natacha Y. N. Dias, Helenice Mercier, Elenice de C. Conforto,
Denise de C. Rossa-Feres.

Diverse invertebrate and vertebrate species live in association with plants of the large Neotropical family... more Diverse invertebrate and vertebrate species live in association with plants of the large Neotropical family Bromeliaceae. Although previous studies have assumed that debris of associated organisms improves plant nutrition, so far little evidence supports this assumption. In this study we used isotopic (15N) and physiological methods to investigate if the treefrog Scinax hayii, which uses the tank epiphytic bromeliad Vriesea bituminosa as a diurnal shelter, contributes to host plant nutrition. In the Weld, bromeliads with frogs had higher stable N isotopic composition (
15N) values than those without frogs. Similar results were obtained from a controlled greenhouse experiment. Linear mixing models showed that frog feces and dead termites used to simulate insects that eventually fall inside the bromeliad tank contributed, respectively, 27.7% (§0.07 SE) and 49.6% (§0.50 SE) of the total N of V. bituminosa. Net photosynthetic rate was higher in plants that received feces and termites than in controls; however, this eVect was only detected in the rainy, but not in the dry season. These results demonstrate for the Wrst time that vertebrates contribute to bromeliad nutrition, and that this beneWt is seasonally restricted. Since amphibian–bromeliad associations occur in diverse habitats in South and Central America, this mechanism for deriving nutrients may be important in bromeliad systems throughout the Neotropics.

The frog Dermatonotus muelleri (Boettger 1885) (Anura Microhylidae) shifts its search tactics in response to two different prey distributions

by Fausto Nomura

Co-authored with D.C. Rossa-Feres. On-line first.

Search tactics are cognitive processes that organisms use to elicit a group of related and sequential behaviours that... more Search tactics are cognitive processes that organisms use to elicit a group of related and sequential behaviours that allow them to locate available resources. Some species can modify their search tactics according to different ecological conditions,
such as abundance and distribution of prey. In this study, we investigate the mechanisms that elicit this shift in search tactics using the frog D. muelleri as the subject of a laboratory experiment. The shift in search tactics was measured by differences in the rate of the exploratory behaviours during the foraging activity. Under experimental conditions, D. muelleri alternates from sit-and-wait foraging when foraging within a patch, to widely foraging when locating prey aggregations. The same behavioural response has also been observed in other animal groups (fishes and invertebrates), elicited by two ecological conditions, a shift in prey spatial distribution and a shift in prey abundance through time. In general, when habitat components vary in time, causing temporal fluctuations in prey abundance, the predator evolves flexible search tactics mediated by prey density. On the other hand, if these components vary in space resulting in patchy distribution of the prey, the predators
evolve search tactics mediated by the resource’s spatial distribution. Therefore, both temporal instability (e.g. temporal fluctuations in prey density) and environmental heterogeneity (e.g. patch distribution of the food resource) favour the appearance of flexible search tactics.

Are you experienced? Predator type and predator experience trade-offs in relation to tadpole mortality rates

by Fausto Nomura

Co-authored with V. H. M. do Prado, F. R. da Silva, R. E. Borges, N. Y. N. Dias & D. de C. Rossa-Feres

Cryptic behavior and unpalatability are common defensive strategies that occur in different taxonomic groups, but the... more Cryptic behavior and unpalatability are common defensive strategies that occur in different taxonomic groups, but the effectiveness of these defensive strategies is context dependent, varying with predator type and co-occurring species. We tested this assumption by measuring the mortality rates of Eupemphix nattereri (cryptic behavior) and Rhinella schneideri (unpalatable) tadpoles in association with the predatory fish Oreochromis niloticus (vertebrate) and the dragonfly larvae of Aeshna sp. (invertebrate). We designed a second experiment to evaluate whether fish predators are capable of learning to avoid unpalatable prey once they have encountered it. Our results showed that fish preyed selectively on palatable tadpoles, avoiding unpalatable tadpoles and that the odonate larvae were more efficient in preying on the more active unpalatable tadpoles and less efficient in capturing those tadpoles that presented cryptic behaviors. Additionally, our data suggest that the antipredator traits of tadpoles can interact with each other, with cryptic tadpoles showing lesser mortality when co-occurring with unpalatable tadpoles and odonate predators. Unpalatable tadpoles also increase the mortality of cryptic tadpoles in the presence of experienced fish predators. These prey traits interact in modifying the prey preference of the predator, which constitutes a preyinduced trait-mediated interaction (TMI). This type of TMI is dependent on the system complexity (number of predator and prey species interactions) and could define food web properties, such as the role of predators and the number of competitor species in the system.