Disponibilidad y uso de recursos tróficos por Lacerta schreiberi y Podarcis bocagei en simpatría en una localidad de la Cordillera Cantábrica, España

Salvador, Alfredo; Domínguez, Juan Carlos

doi:10.1163/156853890x00159

Cited by 6 publications

References 8 publications

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Effects of prey size and foraging mode on the ontogenetic change in feeding niche ofColostethus stepheni (Anura: Dendrobatidae)

Lima

Moreira

1993

Oecologia

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The feeding niche ofColostethus stepheni changes during ontogeny. Small individuals eat small arthropods, principally mites and collembolans, and larger frogs eat bigger prey of other types. The shift in prey types is not a passive effect of selection for bigger prey. There is a strong relationship between electivity for prey types and frog size, independent of electivity for prey size. Four indices of general activity during foraging (number of movements, velocity, total area utilized and time spent moving), which are associated with electivity for prey types in adult frogs and lizards, did not predict the ontogenetic change in the diet ofC. stepheni. Apparently, the behavioral changes that cause the ontogenetic change inC. stepheni are more subtle than shifts in general activity during foraging. Studies of niche partitioning in communities of anurans that do not take into consideration ontogenetic changes in diet and seasonal changes in the size structures of populations present a partial and possibly erroneous picture of the potential interactions among species.

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Effects of prey size and foraging mode on the ontogenetic change in feeding niche ofColostethus stepheni (Anura: Dendrobatidae)

Lima

Moreira

1993

Oecologia

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From set menu toa la carte. Linking issues in trophic ecology of Mediterranean lacertids

Carretero

2004

Italian Journal of Zoology

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Lacertids are the dominant group of lizards throughout the Mediterranean Basin. Their role in food web transfer of matter and energy from arthropods and other small invertebrates to birds and mammals constitutes a major function within Mediterranean ecosystems. For many years, prey consumption by lacertids was thought to be almost indiscriminate, not much more than a byproduct of habitat use. However, increasing evidence does not support this passive view. Analyses of prey availability have revealed active prey selection/avoidance in several species. Others show an internal tendency (i.e., historical constraints) to consume specific animal items (ants, clumped prey) or plant matter (seeds, nectar, pollen, leaves). Behavioural experiments showed that lacertids not only identify different prey types by both visual and chemical cues but also modify their feeding behaviour integrating past experiences. Furthermore, size, sex, reproductive state, body condition, tail loss and probably other lizard features are relevant for feeding ecology. However, less attention has been devoted to abiotic factors such as temperature and humidity. More experimental studies of the influences of competitors, predators and parasites on diet are needed. Even though it is controversial, optimal foraging theory provides a conceptual background for future studies. The evolutionary history of the various lacertid lineages, which constrains their morphology and physiology and eventually produces exaptative traits, is to be considered as well. Finally, methodology in field sampling, lab work and statistical analysis needs to be developed. Recommendations are given as to when and where to sample, which compartment should be analysed, which is the appropriate sample size, how to assess trophic availability, which statistical descriptors should be used and how they should be compared.

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Do lizard communities partition the trophic niche? A worldwide meta‐analysis using null models

Luiselli¹

2007

Oikos

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Lizards have been widely used as model organisms in community ecology over the past 30 years. I have reviewed more than 50 studies from the literature on the community ecology of lizards worldwide, with a focus on studies from 1990Á 2007. I determined if there is support for the hypotheses that many lizard communities 1) are non-randomly organized along the trophic niche dimension, and 2) partition the available food resource to minimize interspecific competition. I used data on number of prey items and percentage of prey volume, to calculate dietary overlap among species. I compared true datasets to randomly generate new datasets produced by 3 )10 4 Monte Carlo permutations using two algorithms (RA2 and RA3). The great majority (more than 80%) of the communities were randomly organized along the trophic niche dimension using RA2 or RA3; the frequency of occurrence of detecting a non-random structure in lizard community dietary studies did not differ significantly between datasets based on either number of prey items or prey volume. Thus, lizard communities usually do not partition the trophic niche axis. Concerning the number of prey items, logistic regression models showed that the presence of a structure in the dataset did not depend on number of species, method employed to obtain dietary data, matrix size, or location (continent), but instead significantly depended on whether a community was tropical. Concerning prey volume, presence of a structure in the dataset also did not depend on number of species, method employed to obtain dietary data, and tropical vs non-tropical origin, but was marginally dependent on continent (South America was favoured for identifying a structure in the dataset) and matrix size. In general, a structure in the dataset was more often uncovered by using RA2 than RA3. Overall, I conclude that 1) lizard communities are unlikely to partition available food resources, and 2) as the method for identifying dietary items does not allow for accurate prey identification (at least at the genus level), there is a risk of obtaining false null results about community structure. This is because structure along the trophic niche axis is genuinely rare in lizards and also because inappropriate methods may erroneously lead to this conclusion. Therefore, conclusions from studies utilizing stomach dissection as a source of diet data (still common in the literature) should be cautiously considered for ethical reasons and because it is difficult to find any difference between stomach-dissection and fecal-pellet data when assessing the presence of a structure in datasets. My data also showed there are minor differences in the probability of detecting a structure in datasets using prey item number or prey volume data for lizards. The biases, both statistical and biological, associated with this meta-analysis are discussed.

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Disponibilidad y uso de recursos tróficos por Lacerta schreiberi y Podarcis bocagei en simpatría en una localidad de la Cordillera Cantábrica, España

Cited by 6 publications

References 8 publications

Effects of prey size and foraging mode on the ontogenetic change in feeding niche ofColostethus stepheni (Anura: Dendrobatidae)

Effects of prey size and foraging mode on the ontogenetic change in feeding niche ofColostethus stepheni (Anura: Dendrobatidae)

From set menu toa la carte. Linking issues in trophic ecology of Mediterranean lacertids

Do lizard communities partition the trophic niche? A worldwide meta‐analysis using null models

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