Estrés fisiológico en urogallos cantábricos (Tetrao urogallus cantabricus) silvestres y en cautividad: variaciones temporales e implicaciones metodológicas

El estudio de los factores ambientales que pueden explicar los niveles de estrés fisiológico en poblaciones naturales es de vital importancia para especies vulnerables, ya que puede influir en la mortalidad de los individuos y, por tanto, en la viabilidad poblacional. En este trabajo se exploran los condicionantes ambientales que pueden explicar las variaciones de estrés fisiológico medido a través de niveles de corticosterona en plumas de urogallo cantábrico (Tetrao urogallus cantabricus). Se emplearon muestras recogidas de individuos en cautividad y de individuos silvestres. Las muestras recogidas de los individuos silvestres se recopilaron desde 1998 hasta 2017 y se consideraron 35 variables climáticas de temperatura y precipitación. Los análisis de repetibilidad sugirieron que los niveles de corticosterona en la combinación de plumas corporales y secundarias fueron repetibles dentro de individuos, mientras que en la combinación de plumas corporales y primarias no lo fueron, por lo que se consideraron sólo las medidas de las plumas corporales y secundarias. Los resultados indicaron que los individuos en cautividad tuvieron un menor estrés fisiológico y que, en individuos silvestres, hubo un incremento de los niveles de estrés hasta estabilizarse en los últimos años de estudio. Ninguna variable climática estuvo relacionada con los niveles de estrés fisiológico. Especulamos que la tendencia temporal en los niveles de estrés podría estar reflejando limitaciones alimenticias, quizá asociadas a cambios en la estructura o composición del hábitat o interacciones con otras especies silvestres o ganado doméstico, lo que podría explicar el menor estrés fisiológico de los individuos en cautividad. Desde el punto de vista metodológico, las plumas secundarias o corporales, independientemente del sexo, serían las preferibles para establecer un monitoreo del estrés fisiológico del urogallo en condiciones naturales o de cautividad.

Molecular dietary analyses of western capercaillies (Tetrao urogallus) reveal a diverse diet

ABSTRACTConservation strategies centred around species habitat protection rely on species’ dietary information. One species at the focal point of conservation efforts is the herbivorous grouse, the western capercaillie (Tetrao urogallus). Traditional microhistological analysis of crop contents or faeces and/or direct observations are time-consuming and at low taxonomic resolution. Thus, limited knowledge on diet is hampering conservation efforts. Here we use non-invasive environmental DNA (eDNA) metabarcoding on DNA extracted from faeces to present the first large-scale molecular dietary analysis of capercaillies. Faecal samples were collected from seven populations located in Norway (Finnmark, Troms, Trøndelag, Innlandet) and France (Vosges, Jura, Pyrenees) (n=172). We detected 122 plant taxa belonging to 46 plant families of which 37.7% of the detected taxa could be identified at species level. The average dietary richness of each sample was 7 ± 5 SD taxa. The most frequently occurring plant groups with the highest relative read abundance (RRA) were trees and dwarf shrubs, in particular, Pinus and Vaccinium myrtillus, respectively. There was a difference in dietary composition (RRA) between samples collected from the different locations (adonis F5,86= 11.01, p <0.05) and seasons (adonis F2,03= 0.64, p <0.05). Dietary composition also differed between sexes at each location (adonis F1,47 = 2.77, p <0.05), although not significant for all data combined. In total, 35 taxa (36.84% of taxa recorded) were new capercaillie food items compared to existing knowledge. The non-invasive molecular dietary analysis applied in this study provides new ecological understanding of capercaillies’ diet which can have real conservation implications. The broad variety of diet items indicates that vegetation does not limit food intake. This plasticity in diet suggests that other factors including disturbed mating grounds and not diet could be the main threat to their survival.

Past, present, future: tracking and simulating genetic differentiation over time in a closed metapopulation system

Genetic differentiation plays an essential role in the assessment of metapopulation systems of conservation concern. Migration rates affect the degree of genetic differentiation between subpopulations, with increasing genetic differentiation leading to increasing extinction risk. Analyses of genetic differentiation repeated over time together with projections into the future are therefore important to inform conservation. We investigated genetic differentiation in a closed metapopulation system of an obligate forest grouse, the Western capercaillieTetrao urogallus, by comparing microsatellite population structure between a historic and a recent time period. We found an increase in genetic differentiation over a period of approximately 15 years. Making use of forward simulations accounting for population dynamics and genetics from both time periods, we explored future genetic differentiation by implementing scenarios of differing migration rates. Using migration rates derived from the recent dataset, simulations predicted further increase of genetic differentiation by 2050. We then examined effects of two realistic yet hypothetical migration scenarios on genetic differentiation. While isolation of a subpopulation led to overall increased genetic differentiation, the re-establishment of connectivity between two subpopulations maintained genetic differentiation at recent levels. Our results emphasize the importance of maintaining connectivity between subpopulations in order to prevent further genetic differentiation and loss of genetic variation. The simulation set-up we developed is highly adaptable and will aid researchers and conservationists alike in anticipating consequences of conservation strategies for metapopulation systems.