Data from: The roles of demography and genetics in the early stages of colonization

Colonization success increases with the size of the founding group. Both demographic and genetic factors underlie this relationship, yet because genetic diversity normally increases with numbers of individuals, their relative importance remains unclear. Furthermore, their influence may depend on the environment and may change as colonization progresses from establishment through population growth and then dispersal. We tested the roles of genetics, demography and environment in the founding of Tribolium castaneum populations. Using three genetic backgrounds (inbred to outbred), we released individuals of four founding sizes (2–32) into two environments (natal and novel), and measured establishment success, initial population growth and dispersal. Establishment increased with founding size, whereas population growth was shaped by founding size, genetic background and environment. Population growth was depressed by inbreeding at small founding sizes, but growth rates were similar across genetic backgrounds at large founding size, an interaction indicating that the magnitude of the genetic effects depends upon founding population size. Dispersal rates increased with genetic diversity. These results suggest that numbers of individuals may drive initial establishment, but that subsequent population growth and spread, even in the first generation of colonization, can be driven by genetic processes, including both reduced growth owing to inbreeding depression, and increased dispersal with increased genetic diversity.

定殖成功率随奠基种群规模的增大而提升。种群统计学与遗传因素共同构成了这一关联的基础，但由于遗传多样性通常随个体数量增加而升高，二者的相对重要性仍未明确。此外，二者的影响可能依赖于环境条件，且会随着定殖进程——从种群建立、种群增长到扩散阶段——发生动态变化。本研究以赤拟谷盗（Tribolium castaneum）种群的建群过程为对象，探究了遗传、种群统计与环境因素的作用。我们设置了3种遗传背景（从近交到远交），将4种不同奠基规模（2~32只）的个体分别投放至2种环境（原生环境与新异环境）中，并测定了种群建立成功率、初始种群增长速率与扩散能力。种群建立成功率随奠基规模增大而提升，而种群增长则受奠基规模、遗传背景与环境共同调控。当奠基规模较小时，近交作用会抑制种群增长；但当奠基规模较大时，不同遗传背景下的种群增长速率并无显著差异，这一交互效应表明，遗传效应的强度依赖于奠基种群的初始规模。扩散速率随遗传多样性升高而加快。本研究结果表明，个体数量可能是决定初始种群建立的核心因素，但后续的种群增长与扩散——即使是在定殖的第一代——也可受遗传过程调控，其中既包括近交衰退导致的增长抑制，也包括遗传多样性升高所带来的扩散能力提升。