Paths for colonization or exodus? New insights from the brown bear (Ursus arctos) population of the Cantabrian Mountains

Gregório, Inês; Pando, Doriana; Morante, Joaquín; Fonseca, Carlos; Ferreira, Eduardo

doi:10.1371/journal.pone.0227302

Cited by 10 publications

(38 citation statements)

References 66 publications

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“…In a recent genetic study on this population of brown bears, Gregório et al [ 4 ] confirmed that it is structured in two subpopulations (eastern and western), as previously described [ 3 , 5 – 9 ]. These authors also present more evidence of male mediated bidirectional gene flow and admixture between both subpopulations [ 3 , 8 ].…”

Section: Introductionsupporting

confidence: 79%

“…To answer the question posed by Gregório et al [ 4 ] (“Paths for colonization or exodus?”) we use four approaches. Firstly, we discuss the exodus concept vs .…”

Section: Methodsmentioning

confidence: 99%

“…Thirdly, we offer an alternative interpretation considering the available genetic information on the Cantabrian bear population published to date. Finally, we provide crucial demographic information for this bear population that is missing in the paper of Gregório et al [ 4 ].…”

Section: Methodsmentioning

confidence: 99%

“…These authors also present more evidence of male mediated bidirectional gene flow and admixture between both subpopulations [ 3 , 8 ]. However, Gregório et al [ 4 ] found an asymmetrical and more intense gene flow from the smaller eastern subpopulation towards the larger western subpopulation, raising the intriguing question that headed the title of their article: does the recent reconnection of both subpopulations mean a process of colonization or of an exodus of bears from the eastern subpopulation to the western one? The authors tended towards the exodus option, and proposed (p. 15) that “bears could be forced to flee from areas with higher human disturbance and poaching, which are more intense in the eastern Cantabrian Mountains”; “It is reasonable to infer that individuals from the eastern Cantabrian subpopulation might be dispersing westwards to seek habitats with less human interference and to escape human persecution”; “Thus, instead of promoting colonization (and reinforcement) of the eastern Cantabrian region by bears from the western Cantabrian Mountains, connectivity between the two subpopulations may operate as a means for eastern Cantabrian bears to find more suitable territories.”…”

Section: Introductionmentioning

confidence: 99%

“…The article by Gregório et al [ 4 ] makes an interesting assessment of the recovery process of this bear population from the genetic point of view, but in our opinion it fails when making an ecological interpretation of the data. Furthermore, their interpretation suffers in our opinion from a major flaw, in that they have not used well-known data on the demographic trend of the eastern bear subpopulation.…”

Section: Introductionmentioning

confidence: 99%

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Not exodus, but population increase and gene flow restoration in Cantabrian brown bear (Ursus arctos) subpopulations. Comment on Gregório et al. 2020

et al. 2020

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In a genetic study on brown bears ( Ursus arctos ) in the Cantabrian Mountains, Gregório et al. (2020) interpreted the asymmetrical gene flow they found from the eastern subpopulation towards the western one as an exodus of bears forced to flee from the eastern nucleus “with higher human disturbance and poaching”, concluding that connectivity may be operating as a means for eastern Cantabrian bears to find more suitable territories. In this reply, we maintain that the explanations of Gregorio et al. contradict the source-sink theory and we also present demographic data not considered by these authors showing that the eastern subpopulation is not declining, but persistently increasing. After reviewing the demographic and genetic studies published during the last 20 years, we conclude that the connectivity between the two subpopulations is operating as a route which allows the regular movement of males and the restoration of the gene flow across the whole Cantabrian population.

show abstract

Section: Introductionsupporting

confidence: 79%

“…To answer the question posed by Gregório et al [ 4 ] (“Paths for colonization or exodus?”) we use four approaches. Firstly, we discuss the exodus concept vs .…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Not exodus, but population increase and gene flow restoration in Cantabrian brown bear (Ursus arctos) subpopulations. Comment on Gregório et al. 2020

et al. 2020

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Importance of data selection and filtering in species distribution models: A case study on the Cantabrian brown bear

et al. 2022

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Species distribution models (SDMs) are powerful tools in ecology and conservation. Choosing the right environmental drivers and filtering species' occurrences taking their biases into account are key factors to consider before modeling. In this case study, we address five common problems arising during the selection of input data for presence‐only SDMs on an example of a generalist species: the endangered Cantabrian brown bear. First, we focus on the selection of environmental variables that may drive its distribution, testing if climatic variables should be considered at a 1‐km analysis grain. Second, we investigate how filtering the species' data in view of (1) their collection procedures, (2) different time frames, (3) dispersal areas, and (4) subpopulations affects the performance and outputs of the models at three different spatial analysis grains (500 m, 1 km, and 5 km). Our results show that models with different input data yielded only minor differences in performance and behaved properly in terms of model validation, although coarsening the analysis grain deteriorated model performance. Still, the contribution of individual variables and the habitat suitability predictions differed among models. We show that a combination of limited data availability and poor selection of environmental variables can lead to inaccurate predictions. Specifically for the brown bear, we conclude that climatic variables should not be considered for exploring habitat suitability and that the best input data for modeling habitat suitability in the study area originate from (1) observations and traces from the (2) most recent period (2006–2019) in which the population is expanding, (3) not considering cells of dispersing bear occurrences and (4) modeling subpopulations independently (as they show distinct habitat preferences). In conclusion, SDMs can serve as a useful tool for generalist species including all available data; still, expert evaluation from the perspective of data suitability for the purpose of modeling and possible biases is recommended. This is especially important when the results are intended for management and conservation purposes at the local level, and for species that respond to the environment at coarse analysis grains.

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Landscape connectivity estimates are affected by spatial resolution, habitat seasonality and population trends

et al. 2021

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Paths for colonization or exodus? New insights from the brown bear (Ursus arctos) population of the Cantabrian Mountains

Cited by 10 publications

References 66 publications

Not exodus, but population increase and gene flow restoration in Cantabrian brown bear (Ursus arctos) subpopulations. Comment on Gregório et al. 2020

Not exodus, but population increase and gene flow restoration in Cantabrian brown bear (Ursus arctos) subpopulations. Comment on Gregório et al. 2020

Importance of data selection and filtering in species distribution models: A case study on the Cantabrian brown bear

Landscape connectivity estimates are affected by spatial resolution, habitat seasonality and population trends

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