Genetic and demographic founder effects have long‐term fitness consequences for colonising populations

Abstract

Colonisation is a fundamental ecological and evolutionary process that drives the distribution and abundance of organisms. The initial ability of colonists to establish is determined largely by the number of founders and their genetic background. We explore the importance of these demographic and genetic properties for longer term persistence and adaptation of populations colonising a novel habitat using experimental populations of Tribolium castaneum. We introduced individuals from three genetic backgrounds (inbred - outbred) into a novel environment at three founding sizes (2-32), and tracked populations for seven generations. Inbreeding had negative effects, whereas outbreeding generally had positive effects on establishment, population growth and long-term persistence. Severe bottlenecks due to small founding sizes reduced genetic variation and fitness but did not prevent adaptation if the founders originated from genetically diverse populations. Thus, we find important and largely independent roles for both demographic and genetic processes in driving colonisation success.

Genetic admixture accelerates invasion via provisioning rapid adaptive evolution

“…A major disturbance to natural and managed ecosystems is posed by the human‐mediated introduction and spread of exotic species (van Kleunen, Dawson, et al, ). Predicting the velocity of biological invasion requires an understanding of ecology and evolutionary dynamics of introduced populations (Ochocki & Miller, ; Szűcs, Melbourne, Tuff, Weiss‐Lehman, & Hufbauer, ; Weiss‐Lehman, Hufbauer, & Melbourne, ; Williams, Kendall, & Levine, ). Multiple introductions, which often involve a large quantity of introduced individuals and genetic variations, can provide demographic and genetic rescues for founding populations (Dlugosch, Anderson, Braasch, Cang, & Gillette, ; Dlugosch & Parker, ; Kolbe et al, ; Roman & Darling, ; Uller & Leimu, ).…”

Potential limits to the benefits of admixture during biological invasion

“…While many factors will shape the success of species introductions and their ecological interactions with recipient environments (Sakai et al, ), there is increasing evidence that genetic factors can play a role in this process (Baker & Stebbins, ; Colautti & Barrett, ; Cox, ; Ellstrand & Schierenbeck, ; Lee, ; Mesgaran et al, ; Rius & Darling, ; Whitney & Gering, ). Understanding when, where, and how genetic changes influence the outcomes of colonization is likely to be crucial to resolving broader questions about when species introductions will lead to establishment and invasive spread (Bock et al, ; Colautti & Lau, ; Dlugosch, Anderson, Braasch, Cang, & Gillette, ; Forsman, ; Hufbauer, ; Lee & Gelembiuk, ; Ochocki & Miller, ; Rius & Darling, ; Szűcs, Melbourne, Tuff, & Hufbauer, ; Szűcs, Melbourne, Tuff, Weiss‐Lehman, & Hufbauer, ; Weiss‐Lehman, Hufbauer, & Melbourne, ; Williams, Kendall, & Levine, ).…”

“…For introduced species in particular, additional inputs of genetic diversity could facilitate both adaptation to the novel environment of introduction and adaptation in traits that facilitate colonization in general, such as increased dispersal ability (Cox, ; Holt, Barfield, & Gomulkiewicz, ; Phillips, Brown, Webb, & Shine, ; Prentis, Wilson, Dormontt, Richardson, & Lowe, ; Thompson, ; Weiss‐Lehman et al, ). Evolutionary rescue should be most likely in populations with low genetic diversity (such that adaptive variation is limiting), and increasingly impactful as the divergence between admixing populations increases and combines a greater numbers of unique alleles (Ochocki & Miller, ; Rieseberg et al, ; Szűcs, Melbourne, et al, ; Wagner et al, ).…”

Monitoring age‐related trends in genomic diversity of Australian lungfish

“…If the Brisbane River population is purely derived from a translocation that took place ~100 years ago, equating to three or four lungfish generations, then divergence of Brisbane from its source population we observe in the SNP data is relatively rapid. But this can be reconciled with the biology of founder events known from other systems, where even small numbers of founders (as low as 2–4 individuals) may produce demographically viable populations that exhibit divergence and reduced genetic diversity relative to their source population as long as the source population is not itself highly inbred (Szűcs, Melbourne, Tuff, Weiss‐Lehman, & Hufbauer, ).…”