Adapt, move or perish : the interaction of genetics and demography in fragmented populations under climate change

In reactie op klimaatverandering verschuift van veel soorten het areaal, maar het is duidelijk dat dit voor lang niet alle soorten snel genoeg gaat. Habitatfragmentatie zal in het algemeen de noodzakelijke areaalverschuivingen vertragen. Er is geopperd dat de combinatie van areaalverschuivingen en de lokale aanpassing van soorten aan de veranderende omstandigheden hun overleving positief zal beïnvloede

Stable partial migration under a genetic threshold model of migratory behaviour

Many species show migratory behaviour in response to seasonal changes in environmental conditions. A peculiar, yet widespread phenomenon is partial migration, when a single population consists of both migratory and non-migratory individuals. There are still many open questions regarding the stability and evolutionary significance of such populations. For passerines the inheritance of migratory activity is best described by the threshold model of quantitative genetics. Such a model has not yet been employed in theoretical studies, in which stability of partially migratory populations is usually linked to group differences in survival or reproduction. Here we develop a parsimonious model featuring a conditional genetic threshold for passerine migratory behaviour under which stable partial migration can be observed, and we explore the resulting selection landscape. Our model results show a cline in migratory behaviour across the landscape, from fully migratory populations to fully residential populations, with a fairly wide zone of partially migratory populations, which is stable in both time and space under a wide range of parameter settings. Temporal stability of the zone is linked with the yearly variance in both migration survival and resident winter survival. In contrast to other theoretical studies, we show that density dependence in winter survival is not essential for observing partially migratory populations. In addition, we observe that selection on the genetic threshold value occurs mainly at the borders of the zone of partial migration. This result suggests that fully migratory and fully residential populations in areas far from the zone of partial migration can harbour genetic diversity that allows the appearance of the alternative phenotype under (a wide range of) different conditions

Consequences of the genetic treshold model for observing partial migration under climate change scenarios

Migration is a widespread phenomenon across the animal kingdom as a response to seasonality in environmental conditions. Partially migratory populations are populations that consist of both migratory and residential individuals. Such populations are very common, yet their stability has long been debated. The inheritance of migratory activity is currently best described by the threshold model of quantitative genetics. The inclusion of such a genetic threshold model for migratory behavior leads to a stable zone in time and space of partially migratory populations under a wide range of demographic parameter values, when assuming stable environmental conditions and unlimited genetic diversity. Migratory species are expected to be particularly sensitive to global warming, as arrival at the breeding grounds might be increasingly mistimed as a result of the uncoupling of long-used cues and actual environmental conditions, with decreasing reproduction as a consequence. Here, we investigate the consequences for migratory behavior and the stability of partially migratory populations under five climate change scenarios and the assumption of a genetic threshold value for migratory behavior in an individual-based model. The results show a spatially and temporally stable zone of partially migratory populations after different lengths of time in all scenarios. In the scenarios in which the species expands its range from a particular set of starting populations, the genetic diversity and location at initialization determine the species’ colonization speed across the zone of partial migration and therefore across the entire landscape. Abruptly changing environmental conditions after model initialization never caused a qualitative change in phenotype distributions, or complete extinction. This suggests that climate change-induced shifts in species’ ranges as well as changes in survival probabilities and reproductive success can be met with flexibility in migratory behavior at the species level, which will reduce the risk of extinction

Bolder Takes All and the role of epigenetics. A comment on Canestrelli et al.: Letter

Refers To Daniele Canestrelli, Roberta Bisconti, Claudio Carere Bolder Takes All? The Behavioral Dimension of Biogeography Trends in Ecology & Evolution, Volume 31, Issue 1, January 2016, Pages 35-43 PDF (1863 K

Landscape genetics of fragmented forests: anticipating climate change by facilitating migration

Habitat fragmentation is a threat to the survival of species and causes population decline, as isolated populations are more susceptible to demographic and genetic stochasticity. This can be compensated for by sufficient spatial connectivity between habitat patches to allow dispersal of individuals among populations. In that case such a network of populations may effectively form a metapopulation. In this paper we discuss some aspects of metapopulation theory, notably with respect to maintaining genetic diversity in fragmented forest patches. In addition we will discuss recent studies that explore ways for forest management to anticipate and mitigate the expected climate change, in relation to range shifts and colonisation opportunitie

Climate change and crop wild relatives: can species track their suitable environment and what do they lose in the process

Crop wild relatives are an increasingly important source of plant genetic resources for plant breeders. Several studies have estimated the effects of climate change on the distribution of crop wild relatives, using species distribution models. In this approach, two important aspects, i.e. species' dispersal capacity and founder effects, are currently not taken into account. Neglecting these aspects can lead to an underestimation of the climate change-induced threat to the size of the species range and the conservation of range-wide levels of genetic diversity. This paper presents two recommendations for the interpretation of the results obtained with these models. The integration of process-based simulation models and statistical species distribution models will facilitate the inclusion of dispersal processes and founder effects in future assessments of the resilience of plant genetic resources under climate change

Landscape prerequisites for the survival of a modelled metapopulation and its neutral genetic diversity are affected by climate change

In response to climate change a species may move, adapt, or go extinct. For the adaptability of a population its genetic diversity is essential, but climate change-induced range shifts can cause a loss of genetic diversity. We investigated how landscape structure affects the level and distribution of genetic diversity in metapopulations subject to climate change-induced range shifts. For this we used the spatially explicit, individual-based model METAPHOR which simulates metapopulation demography and genetics under different temperature increase scenarios. The results indicated that increasing total habitat area may enhance the maintenance of the genetic diversity in metapopulations while they are shifting their range under climate change. However, the results also showed that a high level of total habitat area did not prevent the populations in the newly colonised habitat area of being depleted of much of the original genetic diversity. We therefore conclude that enhancing landscape connectivity may lead to a delayed loss of genetic diversity in metapopulations under climate change, but that additional measures would be necessary to ensure its long-term conservation. Importantly, our simulations also show that a landscape which could be regarded as well-structured under stable climatic conditions, may be inferior for the conservation of genetic diversity during a range shift. This is important information for landscape management when developing strategies for the in situ conservation of genetic variation in natural populations under climate change

Data from: Maternal effects in a wild songbird are environmentally plastic but only marginally alter the rate of adaptation

Despite ample evidence for the presence of maternal effects (MEs) in a variety of traits and strong theoretical indications for their evolutionary consequences, empirical evidence to what extent MEs can influence evolutionary responses to selection remains ambiguous. We tested the degree to which MEs can alter the rate of adaptation of a key life-history trait, clutch size, using an individual-based model approach parameterized with experimental data from a long-term study of great tits (Parus major). We modeled two types of MEs: (i) an environmentally plastic ME, in which the relationship between maternal and offspring clutch size depended on the maternal environment via offspring condition, and (ii) a fixed ME, in which this relationship was constant. Although both types of ME affected the rate of adaptation following an abrupt environmental shift, the overall effects were small. We conclude that evolutionary consequences of MEs are modest at best in our study system, at least for the trait and the particular type of ME we considered here. A closer link between theoretical and empirical work on MEs would hence be useful to obtain accurate predictions about the evolutionary consequences of MEs more generally