Dataset Information

Populations Are Differentiated in Biological Rhythms without Explicit Elevational Clines in the Plant Mimulus laciniatus.

ABSTRACT: Environmental variation along an elevational gradient can yield phenotypic differentiation resulting from varying selection pressures on plant traits related to seasonal responses. Thus, genetic clines can evolve in a suite of traits, including the circadian clock, that drives daily cycling in varied traits and that shares its genetic background with adaptation to seasonality. We used populations of annual Mimulus laciniatus from different elevations in the Sierra Nevada in California to explore among-population differentiation in the circadian clock, flowering responses to photoperiod, and phenological traits (days to cotyledon emergence, days to flowering, and days to seed ripening) in controlled common-garden conditions. Further, we examined correlations of these traits with environmental variables related to temperature and precipitation. We observed that the circadian period in leaf movement was differentiated among populations sampled within about 100 km, with population means varying by 1.6 h. Significant local genetic variation occurred within 2 populations in which circadian period among families varied by up to 1.8 h. Replicated treatments with variable ecologically relevant photoperiods revealed marked population differentiation in critical day length for flowering that ranged from 11.0 to 14.1 h, corresponding to the time period between late February and mid-May in the wild. Flowering time varied among populations in a 14-h photoperiod. Regardless of this substantial population-level diversity, obvious linear clinality in trait variability across elevations could not be determined based on our genotypic sample; it is possible that more complex spatial patterns of variation arise in complex terrains such as those in the Sierra Nevada. Moreover, we did not find statistically significant bivariate correlations between population means of different traits. Our research contributes to the understanding of genetic variation in the circadian clock and in seasonal responses in natural populations, highlighting the need for more comprehensive investigations on the association between the clock and other adaptive traits in plants.

SUBMITTER: Leinonen PH

PROVIDER: S-EPMC7534027 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Populations Are Differentiated in Biological Rhythms without Explicit Elevational Clines in the Plant <i>Mimulus laciniatus</i>.

Leinonen Päivi H PH Salmela Matti J MJ Greenham Kathleen K McClung C Robertson CR Willis John H JH

Journal of biological rhythms 20200706 5

Environmental variation along an elevational gradient can yield phenotypic differentiation resulting from varying selection pressures on plant traits related to seasonal responses. Thus, genetic clines can evolve in a suite of traits, including the circadian clock, that drives daily cycling in varied traits and that shares its genetic background with adaptation to seasonality. We used populations of annual <i>Mimulus laciniatus</i> from different elevations in the Sierra Nevada in California to ...[more]

PMID: 32628567

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Project description:To what extent is insect hopping and feeding performance, which constrains the ability to obtain and assimilate resources, thermally adapted along an elevation gradient? Does temperature dependence vary between populations and species and can differences account for individualistic responses to past climate change? We investigate these questions for three species of grasshoppers along a Rocky Mountain elevation gradient. All species and populations exhibit warm adaptation for consumption and digestion, with only modest inter- and intra-specific differences. Species differ substantially in the temperature of peak hopping performance. Low-elevation populations of the warm-adapted species exhibit the highest performance at high temperatures and the lowest performance at low temperatures. Developmental plasticity influences the temperature dependence of performance; grasshoppers reared at higher temperatures perform better at higher temperatures and possess broader thermal tolerance. We fitted thermal performance curves to examine whether performance shifts can account for changes in abundance between initial surveys in 1958-1960 and recent surveys since 2006. All species and populations are able to achieve greater feeding rates now. Estimated shifts in hopping performance vary between species and along the elevation gradient. The cool-adapted species has experienced declines in hopping performance, particularly at the lower elevation sites, while the warm-adapted species has experienced increases in performance concentrated at higher elevations. These estimated performance shifts broadly concur with observed abundance shifts. Performance metrics may have a greater potential to elucidate differential responses to climate change between populations and species than coarser and oft-used proxies, such as thermal tolerance. Assessing performance directly when temperature dependence varies between processes such as the acquisition and assimilation of energy may be essential to understanding population- and species-level impacts.

Project description:BackgroundThe Algerian honey bee population is composed of two described subspecies A. m. intermissa and A. m. sahariensis, of which little is known regarding population genomics, both in terms of genetic differentiation and of possible contamination by exogenous stock. Moreover, the phenotypic differences between the two subspecies are expected to translate into genetic differences and possible adaptation to heat and drought in A. m. sahariensis. To shed light on the structure of this population and to integrate these two subspecies in the growing dataset of available haploid drone sequences, we performed whole-genome sequencing of 151 haploid drones.ResultsIntegrated analysis of our drone sequences with a similar dataset of European reference populations did not detect any significant admixture in the Algerian honey bees. Interestingly, most of the genetic variation was not found between the A. m. intermissa and A. m. sahariensis subspecies; instead, two main genetic clusters were found along an East-West axis. We found that the correlation between genetic and geographic distances was higher in the Western cluster and that close-family relationships were mostly detected in the Eastern cluster, sometimes at long distances. In addition, we selected a panel of 96 ancestry-informative markers to decide whether a sampled bee is Algerian or not, and tested this panel in simulated cases of admixture.ConclusionsThe differences between the two main genetic clusters suggest differential breeding management between eastern and western Algeria, with greater exchange of genetic material over long distances in the east. The lack of detected admixture events suggests that, unlike what is seen in many places worldwide, imports of queens from foreign countries do not seem to have occurred on a large scale in Algeria, a finding that is relevant for conservation purposes. In addition, the proposed panel of 96 markers was found effective to distinguish Algerian from European honey bees. Therefore, we conclude that applying this approach to other taxa is promising, in particular when genetic differentiation is difficult to capture.

Dataset Information

Populations Are Differentiated in Biological Rhythms without Explicit Elevational Clines in the Plant Mimulus laciniatus.

Publications

Populations Are Differentiated in Biological Rhythms without Explicit Elevational Clines in the Plant <i>Mimulus laciniatus</i>.

Similar Datasets

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