Data from: Environmentally induced development costs underlie fitness tradeoffs

Local adaptation can lead to genotype‐by‐environment interactions, which can create fitness tradeoffs in alternative environments, and govern the distribution of biodiversity across geographic landscapes. Exploring the ecological circumstances that promote the evolution of fitness tradeoffs requires identifying how natural selection operates and during which ontogenetic stages natural selection is strongest. When organisms disperse to areas outside their natural range, tradeoffs might emerge when organisms struggle to reach key life history stages, or alternatively, die shortly after reaching life history stages if there are greater risks of mortality associated with costs to developing in novel environments. We used multiple populations from four ecotypes of an Australian native wildflower (Senecio pinnatifolius) in reciprocal transplants to explore how fitness tradeoffs arise across ontogeny. We then assessed whether the survival probability for plants from native and foreign populations was contingent on reaching key developmental stages. We found that fitness tradeoffs emerged as ontogeny progressed when native plants were more successful than foreign plants at reaching seedling establishment and maturity. Native and foreign plants that failed to reach seedling establishment died at the same rate, but plants from foreign populations died quicker than native plants after reaching seedling establishment, and died quicker regardless of whether they reached sexual maturity or not. Development rates were similar for native and foreign populations, but changed depending on the environment. Together, our results suggest that natural selection for environment‐specific traits early in life history created tradeoffs between contrasting environments. Plants from foreign populations were either unable to develop to seedling establishment, or they suffered increased mortality as a consequence of reaching seedling establishment. The observation of tradeoffs together with environmentally dependent changes in development rate suggest that foreign environments induce organisms to develop at a rate different from their native habitat, incurring consequences for lifetime fitness and population divergence.

本地适应可引发基因型-环境互作（genotype-by-environment interactions），该互作既能在异质环境中催生适合度权衡（fitness tradeoffs），又能调控生物多样性在地理景观中的分布格局。探究能够促进适合度权衡演化的生态条件，需明确自然选择的作用机制，以及自然选择作用最强的个体发育阶段。当生物扩散至其自然分布范围之外的区域时，要么因难以抵达关键生活史阶段而产生适合度权衡，要么若在新生境中发育需承担更高的死亡风险代价，则会在抵达生活史阶段后不久死亡。本研究以4种生态型的澳大利亚本土野生植物菊叶千里光（*Senecio pinnatifolius*）的多个种群为实验材料，通过互惠移植实验（reciprocal transplants）探究适合度权衡如何随个体发育进程产生。随后，本研究评估了本土种群与外来种群植株的存活概率是否取决于其能否抵达关键发育阶段。结果发现，随着个体发育推进，本土植株在幼苗建成（seedling establishment）与成熟阶段的表现优于外来植株，此时便出现了适合度权衡。未抵达幼苗建成阶段的本土与外来植株死亡率并无差异，但抵达幼苗建成阶段后，外来种群植株的死亡速度快于本土植株；且无论是否达到性成熟（sexual maturity），外来植株的死亡速度均更快。本土与外来种群的整体发育速率相近，但会随环境不同而发生改变。综合来看，本研究结果表明，生活史早期针对环境特异性性状的自然选择，在不同生境之间催生了适合度权衡。外来种群植株要么无法发育至幼苗建成阶段，要么在抵达幼苗建成阶段后因该发育过程而面临更高的死亡风险。结合适合度权衡的观测结果与环境依赖性的发育速率变化，可知外来生境会诱导生物以不同于原生境的速率发育，进而对终生适合度（lifetime fitness）与种群分化（population divergence）产生影响。