Indications of transgenerational phenotypic plasticity for morphological traits in Bromus tectorum under a two-generation reciprocal drought experiment

Invasive plant species such as Bromus tectorum pose a substantial threat to low-resilience ecosystems such as the sagebrush steppe in the North American intermountain west. Determining the extent to which B. tectorum expresses transgenerational morphological plasticity in response to drought is necessary for understanding how rapidly the species may acclimate to novel climates and colonize new environments. We investigated transgenerational plasticity of stomatal density, root and shoot length, and root and shoot length ratio across replicates of four genotypes reciprocally subjected to two generations of high and low watering regimes. Average stomatal density of offspring of water-limited parents did not differ based on whether they received high or low water treatments. Well-watered offspring of parents from the low water treatment had significantly longer roots and shoots than water-limited offspring. Water-limited offspring of parents from the low watering treatment displayed greater root : shoot lengths than did well-watered offspring. Additionally, genetic variation for phenotypic plasticity was detected for root and shoot length as well as the ratio of root : shoot length, but not for stomatal density. We conclude that B. tectorum is phenotypically plastic in response to drought and furthermore displays complex tradeoffs and transgenerational phenotypic plasticity for morphological traits, which together may influence both how the species will cope with climate change and our ability to control the species.

Indications of transgenerational phenotypic plasticity for morphological traits in Bromus tectorum under a two-generation reciprocal drought experiment

Invasive plant species such as Bromus tectorum pose a substantial threat to low-resilience ecosystems such as the sagebrush steppe in the North American intermountain west. Determining the extent to which B. tectorum expresses transgenerational morphological plasticity in response to drought is necessary for understanding how rapidly the species may acclimate to novel climates and colonize new environments. We investigated transgenerational plasticity of stomatal density, root and shoot length, and root and shoot length ratio across replicates of four genotypes reciprocally subjected to two generations of high and low watering regimes. Average stomatal density of offspring of water-limited parents did not differ based on whether they received high or low water treatments. Well-watered offspring of parents from the low water treatment had significantly longer roots and shoots than water-limited offspring. Water-limited offspring of parents from the low watering treatment displayed greater root : shoot lengths than did well-watered offspring. Additionally, genetic variation for phenotypic plasticity was detected for root and shoot length as well as the ratio of root : shoot length, but not for stomatal density. We conclude that B. tectorum is phenotypically plastic in response to drought and furthermore displays complex tradeoffs and transgenerational phenotypic plasticity for morphological traits, which together may influence both how the species will cope with climate change and our ability to control the species.

Maternal corticosterone increases thermal sensitivity of heart rate in lizard embryos

While it is well established that maternal stress hormones, such as corticosterone (CORT), can induce transgenerational phenotypic plasticity, few studies have addressed the influence of maternal CORT on pre-natal life stages. We tested the hypothesis that experimentally increased CORT levels of gravid female eastern fence lizards ( Sceloporus undulatus ) would alter within-egg embryonic phenotype, particularly heart rates. We found that embryos from CORT-treated mothers had heart rates that increased faster with increasing temperature, resulting in higher heart rates at developmentally relevant temperatures but similar heart rates at maintenance relevant temperatures, compared with embryos of control mothers. Thus, maternal CORT appears to alter the physiology of pre-natal offspring. This may speed development and decrease the amount of time spent in eggs, the most vulnerable stage of life.