Biology subjects

Herfindal, I.

Publications and source records attributed to Herfindal, I..

3 recordsLinked to original sources

bioRxiv2023

How do life history traits influence the environment's effect on population synchrony? Insights from European birds and insects

Populations closer together in space are more likely to experience shared environmental fluctuations. This correlation in experienced environmental conditions is the main driver of spatial population synchrony, defined as the tendency for geographically separate populations of the same species to exhibit parallel fluctuations in abundance over time. Morans theorem states that spatially distinct populations are expected to show the same synchrony in their population dynamics as the synchrony in their environment. However, this is rarely the case in the wild, and the population synchrony of different species inhabiting the same area is rarely similar. These species-specific differences in how the environment synchronizes populations can be due to life history traits that make some species more susceptible to environmental stochasticity, such as reduced mobility or faster pace of life. In this study, we compiled long-term annual abundance datasets on European birds and insects (Lepidoptera sp. and Bombus sp.) to identify how environmental synchrony (i.e., positively spatially correlated fluctuations in the environment, also called the Moran effect) affects species population synchrony. As expected, the environment synchronized populations of both birds and insects. Populations experiencing correlated fluctuations in precipitation or temperature had higher synchrony in annual population growth rates. Birds were more strongly synchronized by temperature, while precipitation was a stronger driver of synchrony in insects. In birds, species with short generation times had a stronger synchronizing effect of the environment compared to species with long generation times. Moreover, in birds the effects of synchrony in the environment also depended on movement propensity, with a positive impact for resident and short-distance migration species. In insects, annual population synchrony was affected by species movement propensity and dietary niche breadth, but these traits did not modify the effects of environmental synchrony. Our study provides empirical support for the prediction that spatial correlation in population dynamics is more influenced by environmental stochasticity for life histories with lower mobility and faster pace of life, but only in birds. By quantifying spatial population synchrony across different levels of environmental synchrony and life history traits, our study improves the understanding of the Moran effect as well as factors that drive population persistence in the face of environmental change.

ecology↗

bioRxiv2023

Identifying the environmental drivers of corridors and predicting connectivity between seasonal ranges in multiple populations of Alpine ibex (Capra ibex) as tools for conserving migration

Seasonal migrations are central ecological processes connecting populations, species and ecosystems in time and space. Land migrations, such as those of ungulates, are particularly threatened by habitat transformations and fragmentation, climate change and other environmental changes caused by anthropogenic activities. Mountain ungulate migrations are neglected because they are relatively short, although traversing highly heterogeneous altitudinal gradients particularly exposed to anthropogenic threats. Detecting migration routes of these species and understanding their drivers is therefore of primary importance to predict connectivity and preserve ecosystem functions and services. The populations of Alpine ibex Capra ibex, an iconic species endemic to the Alps, have all been reintroduced from the last remnant source population. Because of their biology and conservation history, Alpine ibex populations are mostly disconnected. Hence, despite a general increase in abundance and overall distribution range, their conservation is strictly linked to the interplay between external threats and related behavioral responses, including space use and migration. By using 337 migratory tracks from 425 GPS-collared individuals from 15 Alpine ibex populations distributed across their entire range, we (i) identified the environmental drivers of movement corridors in both spring and autumn and (ii) compared the abilities of three modeling approaches to predict migratory movements between seasonal ranges of the 15 populations. Trade-offs between energy expenditure, food, and cover seemed to be the major driver of migration routes: steep south-facing snow-free slopes were selected while high elevation changes were avoided. This revealed the importance of favorable resources and an attempt to limit energy expenditures and perceived predation risk. Based on these findings, we provided efficient connectivity models to inform conservation of Alpine ibex and its habitats, and a framework for future research investigating connectivity in migratory species.

ecology↗

bioRxiv2023

Generation time and seasonal migration explain variation in spatial population synchrony across European bird species

O_LISpatial population synchrony is common among populations of the same species and is an important predictor of extinction risk. Despite the potential consequences for metapopulation persistence, we still largely lack understanding of what makes one species more likely to be synchronized than another given the same environmental conditions. C_LIO_LIGenerally, environmental conditions on a shared environment or a species sensitivity to the environment can explain the extent of synchrony. Populations that are closer together experience more similar fluctuations in their environments than those populations that are further apart and are therefore more synchronized. The relative importance of environmental and demographic stochasticity for population dynamics is strongly linked to species life history traits, such as pace of life, why may impact population synchrony. For populations that migrate, there may be multiple environmental conditions at different locations driving synchrony. However, the importance of life history and migration strategies in determining patterns of spatial population synchrony have rarely been explored empirically. We therefore hypothesize that generation time, a proxy for pace of life, and migration play an important role in determining spatial population synchrony. C_LIO_LIWe used population abundance data on breeding birds from four countries to investigate patterns of spatial population synchrony in growth rate and abundance. We investigated differences in synchrony across a gradient of generation times in resident, short-distance migrant, and long-distance migrant bird species. C_LIO_LISpecies with shorter generation times were more synchronized than species with longer generation times. Short-distance migrants were more synchronized than long-distance migrants and resident birds. C_LIO_LIOur results provide novel empirical links between spatial population synchrony and species traits known to be of key importance for population dynamics, generation time and migration characteristics. We show how these different mechanisms can be combined to understand species-specific causes of spatial population synchrony. Understanding these specific drivers of spatial population synchrony is important in the face of increasingly severe threats to biodiversity and could be key for successful future conservation outcomes. C_LI

ecology↗