Parataxonomía: un test utilizando escarabajos

The present study examines the utility of parataxonomic sorting (groupings of similar individuals, categorized by non–experts, relying on features of external morphology) using data from a study of beetle communities in four forest habitats in Nova Scotia, Canada. Alpha diversity and the Shannon–Weaver, Simpson, Berger–Parker, and Brillouin indices of diversity, derived from both taxonomic species and parataxonomic units, are compared and yield identical habitat rankings. Beta diversity rankings derived from both data sets do not differ although they produce slightly different rankings. The Elateridae, Curculionidae, Cantharidae, and Staphylinidae had particularly large numbers of "lumping" and "splitting" errors. Although the overall gross sorting error was only 14%, individual families of beetles had errors between 0% and 200% with an average error of 38%. The limitations of the parataxonomic approach are discussed; both in regard to the practical application of the concept, as well its theoretical basis. We note the spillover of this discourse to the subject of what constitutes a species and observe that this discussion has been misplaced due to the unfortunate confusion of the two usages of the term "morphospecies".El presente estudio examina la utilidad de la ordenación parataxonómica (agrupación de individuos similares, categorizados por aficionados, basada en caracteres morfológicos externos) usando los datos de un estudio de comunidades de escarabajos de cuatro hábitats forestales de Nueva Escocia, Canadá. Se comparan la diversidad alfa y los índices de diversidad de Shannon–Weaver, Simpson, Berger–Parker y Brillouin, obtenidos tanto de especies taxonómicas como de unidades parataxonómicas, dando como resultado rankings de hábitats idénticos. Los rankings de diversidad beta procedentes de ambas series de datos no se diferencian, aunque arrojan rankings ligeramente distintos. Los Elateridae, Curculionidae, Cantharidae y Staphylinidae presentaban gran cantidad de errores de "agrupación" y "escisión". Aunque el error de clasificación bruto global era tan solo del 14%, algunas familias de escarabajos presentaban errores de entre el 0 y el 200%, con un error medio del 38%. Se discuten las limitaciones del planteamiento parataxonómico; tanto en lo que hace referencia a la aplicación práctica del concepto, como a su base teórica. Esta discusión nos lleva al tema de en qué consiste una especie y nos permite ver como esta discusión ha sido mal enfocada debido a la desafortunada confusión de los dos usos del término "morfoespecie"

Parataxonomy: a test case using beetles

The present study examines the utility of parataxonomic sorting (groupings of similar individuals, categorized by non-experts, relying on features of external morphology) using data from a study of beetle communities in four forest habitats in Nova Scotia, Canada. Alpha diversity and the Shannon-Weaver, Simpson, Berger-Parker, and Brillouin indices of diversity, derived from both taxonomic species and parataxonomic units, are compared and yield identical habitat rankings. Beta diversity rankings derived from both data sets do not differ although they produce slightly different rankings. The Elateridae, Curculionidae, Cantharidae, and Staphylinidae had particularly large numbers of “lumping” and “splitting” errors. Although the overall gross sorting error was only 14%, individual families of beetles had errors between 0% and 200% with an average error of 38%. The limitations of the parataxonomic approach are discussed; both in regard to the practical application of the concept, as well its theoretical basis. We note the spillover of this discourse to the subject of what constitutes a species and observe that this discussion has been misplaced due to the unfortunate confusion of the two usages of the term “morphospecies”

How Does Spatial Study Design Influence Density Estimates from Spatial Capture-Recapture Models?

When estimating population density from data collected on non-invasive detector arrays, recently developed spatial capture-recapture (SCR) models present an advance over non-spatial models by accounting for individual movement. While these models should be more robust to changes in trapping designs, they have not been well tested. Here we investigate how the spatial arrangement and size of the trapping array influence parameter estimates for SCR models. We analysed black bear data collected with 123 hair snares with an SCR model accounting for differences in detection and movement between sexes and across the trapping occasions. To see how the size of the trap array and trap dispersion influence parameter estimates, we repeated analysis for data from subsets of traps: 50% chosen at random, 50% in the centre of the array and 20% in the South of the array. Additionally, we simulated and analysed data under a suite of trap designs and home range sizes. In the black bear study, we found that results were similar across trap arrays, except when only 20% of the array was used. Black bear density was approximately 10 individuals per 100 km2. Our simulation study showed that SCR models performed well as long as the extent of the trap array was similar to or larger than the extent of individual movement during the study period, and movement was at least half the distance between traps. SCR models performed well across a range of spatial trap setups and animal movements. Contrary to non-spatial capture-recapture models, they do not require the trapping grid to cover an area several times the average home range of the studied species. This renders SCR models more appropriate for the study of wide-ranging mammals and more flexible to design studies targeting multiple species

Deadwood and saproxylic beetle diversity in naturally disturbed and managed spruce forests in Nova Scotia

Volume: 22Start Page: 309End Page: 34

Polyandry enhances offspring survival in an infanticidal species

The adaptive significance of polyandry is an intensely debated subject in sexual selection. For species with male infanticidal behaviour, it has been hypothesized that polyandry evolved as female counterstrategy to offspring loss: by mating with multiple males, females may conceal paternity and so prevent males from killing putative offspring. Here we present, to our knowledge, the first empirical test of this hypothesis in a combined laboratory and field study, and show that multiple mating seems to reduce the risk of infanticide in female bank voles Myodes glareolus. Our findings thus indicate that females of species with non-resource based mating systems, in which males provide nothing but sperm, but commit infanticide, can gain non-genetic fitness benefits from polyandry