Are there studied cases of species gaining genetic traits?

How do soil bacteria gain antibiotic resistance genes?

When soil microbes are exposed to low levels of antibiotics, those with competitive lifestyles—growing fast and using resources efficiently—tend to thrive and carry more antibiotic resistance genes (ARGs). In a study, researchers grew soil microbiota with different concentrations of oxytetracycline and found that at intermediate levels (0.1 and 0.5 mg/L), the total abundance of ARGs increased the most [1]. This suggests that under sub-inhibitory antibiotic stress, bacteria that already carry certain resistance genes gain a growth advantage, leading to a community with more resistance traits.

The study further indicates that the increase in ARGs is linked to bacterial growth strategies: microbes with greater substrate utilization capacity and faster growth carried more ARGs, and the community's genetic traits shifted toward resource acquisition and energy production [1]. This is an example of species gaining genetic traits not by acquiring new genes from scratch, but by selecting for existing genes that confer resistance—a process that can be seen as a form of trait enrichment within a population.

What genetic adaptations help Arctic diatoms survive extreme light?

Arctic diatoms (Thalassiosira gravida) have evolved genetic traits that may give them an edge in polar habitats. When compared with closely related temperate diatoms, Arctic strains showed a preference for 24-hour daylight and had a lower optimum temperature (10.3°C vs. 18.4°C) [2]. More importantly, a screen for convergent amino acid substitutions—a sign of genetic adaptation—identified 26 candidate genes with habitat-specific changes, including DNA polymerase subunits and transcription factors [2]. These genetic traits are particularly abundant in Arctic diatoms and may contribute to competitive advantages beyond what physiological tests alone reveal, potentially hindering temperate diatoms from establishing in the Arctic [2].

Can species gain traits by swapping genes or hybridizing?

In marine bacteria of the genus Endozoicomonas, genome sequencing revealed that they have acquired prophages—viral DNA integrated into their genome—from diverse sources via infection or other gene transfer [4]. This is a clear case of species gaining new genetic material through horizontal gene transfer. Additionally, the bacteria encode giant proteins (15–65 kbp) that cluster into groups associated with antimicrobial peptide synthesis, exotoxin production, and cell adhesion, which may be novel traits acquired over evolutionary time [4].

In Heliconius butterflies, genetic associations between traits that cause reproductive isolation have been studied, showing how divergent traits can accumulate and contribute to speciation [5]. While the abstract does not detail specific new traits, it highlights that genetic architecture can cluster traits that keep species apart, which is relevant to how species might gain or maintain distinct genetic characteristics. Similarly, genome sequencing of Xanthomonas bacteria uncovered novel genetic traits such as genes for coronatine-like compound synthesis and an atypical flagellar gene cluster, raising questions about their evolution and pathogenicity [3].

Sources used in this answer

Related research questions