Data from: A single episode of sexual reproduction can produce large variation in population growth rates under dual stressors

Sexual reproduction has been a central topic in evolutionary biology
because of its many costs: why did organisms evolve sexual reproduction
despite the many costs of sex? To answer the question, researchers have
conducted laboratory experiments to measure population growth rates with
and without sexual reproduction under a stressor. Here we show that a
single episode of sexual reproduction can produce a large amount of
variation in population growth rates under dual stressors by laboratory
experiments of a green alga, Closterium
peracerosum–strigosum–littorale complex. We observed population dynamics
of the alga under dual stressors and confirmed that high salinity and low
pH decreased growth rates. By comparing parental and their hybrid F1
populations, we observed larger variation in growth rates of F1
populations (i.e., transgressive segregation) when pH was low.
Interestingly, even when parental populations had negative growth rates,
some F1 populations showed positive growth rates in severe environmental
conditions due to the large variation in population growth. By utilizing
the recently obtained genomic information of the alga, we conducted a gene
ontology (GO) enrichment analysis and found that genes with copy number
variations between parental strains were more frequently associated with
pH stress-related terms than salt stress-related terms. Our results
suggest that recombination and variation in the number of gene copies
might produce large genetic variation in the F1 generation. This will be
an important step toward a better understanding of the evolution of sex
and evolutionary rescue where rapid contemporary evolution prevents
population extinction in changing environments.