Biology subjects

Bradshaw, H. D.

Publications and source records attributed to Bradshaw, H. D..

3 recordsLinked to original sources

bioRxiv2018

Formation of periodic pigment spots by the reaction-diffusion mechanism

Many organisms exhibit visually striking spotted or striped pigmentation patterns. Turings reaction-diffusion model postulates that such periodic pigmentation patterns form when a local autocatalytic feedback loop and a long-range inhibitory feedback loop interact. At its simplest, this network only requires one self-activating activator that also activates a repressor, which inhibits the activator and diffuses to neighboring cells. However, the molecular activators and repressors fully fitting this versatile model remain elusive. Here, we characterize an R2R3-MYB activator and an R3-MYB repressor in monkeyflowers that correspond to Turings model and explain how periodic anthocyanin spots form. Notably, disrupting this pattern impacts pollinator visitation. Thus, subtle changes in simple reaction-diffusion networks are likely essential contributors to the evolution of the remarkable diversity of periodic pigmentation patterns in flowers.

plant biology↗

bioRxiv2018

Conflict of evolutionary interests between plants and pollinators revealed through functional exploration of flower morphospace

The explosive evolutionary diversification of flowering plants traditionally is attributed to the coevolution of plants and their animal pollinators. Plant-pollinator interactions are held as classical examples of mutualisms - beneficial to both parties - in spite of the fact that most other cases of rapid coevolution are the result of conflicts of interest (e.g., predator-prey, host-parasite, sexual conflict, competition for resources). Could the co-diversification of plants and their pollinators be driven by conflict rather than by mutualism? To address this question, we employed the theoretical morphospace paradigm using a combination of 3D printing, electronic sensing, and machine vision technologies to determine the influence of two flower morphological features (corolla curvature and nectary diameter) on the fitness of both parties: the artificial flower and its hawkmoth pollinator. We found that the two parties have almost opposite interests in corolla curvature evolution, with non-overlapping fitness peaks in flower morphospace, suggesting that the evolutionary radiation of flowering plants and their pollinators could be the result of conflict instead of mutualism.

ecology↗

bioRxiv2017

Rational Design Of A Novel Pollinator Interaction

Diversification of the ca. 250,000 extant flowering plant species has been driven in large part by coevolution with animal pollinators. A recurring pattern of pollinator shifts from hummingbird to hawkmoth pollination has characterized plant speciation in many western North American plant taxa, but in the genus Mimulus (monkeyflowers) section Erythranthe the evolution of hawkmoth pollination from hummingbird-pollinated ancestors has not occurred. We manipulated two flower color loci and tested the attractiveness of the resulting four color phenotypes (red, yellow, pink, white) to naive hawkmoths. Hawkmoths strongly prefer derived colors (yellow, pink, white) over the ancestral red, and prefer the two-locus change (white) to either of the single-locus changes (yellow, pink). The simple flower color genetics underlying this innate pollinator preference suggests a potential path for speciation into an unfilled hawkmoth-pollinated niche, and the deliberate design of a hawkmoth-pollinated flower demonstrates a new, predictive method for studying pollination syndrome evolution.

evolutionary biology↗