Latitudinal and temperature-dependent variation in embryonic development and growth in Rana temporaria

Ane Laugen, A Laurila, J Merilä

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    Abstract

    Variation in seasonal time constraints and temperature along latitudinal gradients are expected to select for life history trait differentiation, but information about the relative importance of these factors in shaping patterns of divergence in embryonic traits remains sparse. We studied embryonic survival, growth and development rates in the common frog (Rana temporaria) along a 1,400-km latitudinal gradient across Sweden by raising embryos from four populations in the laboratory at seven temperatures (9degreesC, 12degreesC, 15degreesC, 18degreesC, 21degreesC, 24degreesC, 27degreesC). We found significant differences in mean values of all traits between the populations and temperature treatments, but this variation was not latitudinally ordered. In general, embryonic survival decreased at the two highest temperatures in all populations, but less so in the southernmost as compared to the other populations. The northernmost population developed slowest at the lowest temperature, while the two mid-latitude populations were slowest at the other temperatures. Hatchling size increased with increasing temperature especially in the two northern populations, whereas the two southern populations showed peak hatchling size at 15degreesC. Analyses of within-population genetic variation with a half-sib design revealed that there was significant additive genetic variation in all traits, and egg size-related maternal effects were important in the case of hatchling size. Overall, our results indicate that unlike larval growth and development, variation in embryonic development and growth in R. temporaria cannot be explained in terms of a latitudinal gradient in season length. While adaptation to a latitudinal variation in temperature might have contributed to the observed differentiation in embryonic performance, the effects of other, perhaps more local environmental. factors, seem to have overridden them in importance.
    Original languageUndefined/Unknown
    Pages (from-to)548–554
    Number of pages7
    JournalOecologia
    Volume135
    Issue number4
    DOIs
    Publication statusPublished - 2003
    MoE publication typeA1 Journal article-refereed

    Keywords

    • amphibians
    • embryonic development
    • geographical variation
    • latitudinal gradient
    • temperature adaptation

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