Gene Family Evolution Reflects Adaptation to Soil Environmental Stressors in the Genome of the Collembolan Orchesella cincta.
Collembola (springtails) are detritivorous hexapods that inhabit the soil and its litter layer. The ecology of the springtail Orchesella cincta is extensively studied in the context of adaptation to anthropogenically disturbed areas. Here, we present a draft genome of an O. cincta reference strain with an estimated size of 286.8 Mbp, containing 20,249 genes. In total, 446 gene families are expanded and 1,169 gene families evolved specific to this lineage. Besides these gene families involved in general biological processes, we observe gene clusters participating in xenobiotic biotransformation. Furthermore, we identified 253 cases of horizontal gene transfer (HGT). Although the largest percentage of them originated from bacteria (37.5%), we observe an unusually high percentage (30.4%) of such genes of fungal origin. The majority of foreign genes are involved in carbohydrate metabolism and cellulose degradation. Moreover, some foreign genes (e.g., bacillopeptidases) expanded after HGT. We hypothesize that horizontally transferred genes could be advantageous for food processing in a soil environment that is full of decaying organic material. Finally, we identified several lineage-specific genes, expanded gene families, and horizontally transferred genes, associated with altered gene expression as a consequence of genetic adaptation to metal stress. This suggests that these genome features may be preadaptations allowing natural selection to act on. In conclusion, this genome study provides a solid foundation for further analysis of evolutionary mechanisms of adaptation to environmental stressors.
Department of Ecological Science, Vrije University Amsterdam, Amsterdam, The Netherlands ann.faddeeva@gmail.com.
Anna
A
Faddeeva-Vakhrusheva
Bioinformatics Group, Wageningen University, Wageningen, The Netherlands.
Martijn F L
MF
Derks
Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands Leiden Genome Technology Center, Leiden University Medical Center, Leiden, The Netherlands.
Seyed Yahya
SY
Anvar
Department of Ecological Science, Vrije University Amsterdam, Amsterdam, The Netherlands.
Valeria
V
Agamennone
Department of Ecological Science, Vrije University Amsterdam, Amsterdam, The Netherlands.
Wouter
W
Suring
Bioinformatics Group, Wageningen University, Wageningen, The Netherlands.
Sandra
S
Smit
Department of Ecological Science, Vrije University Amsterdam, Amsterdam, The Netherlands.
Nico M
NM
van Straalen
Department of Ecological Science, Vrije University Amsterdam, Amsterdam, The Netherlands.
Dick
D
Roelofs
D000222:Adaptation, Physiological; D000818:Animals; D001181:Arthropods / Q000235:genetics* / Q000502:physiology; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D049750:Genome, Insect; D005810:Multigene Family; D012641:Selection, Genetic; D012987:Soil; D013312:Stress, Physiological
D012987:Soil
Collembola; de novo genome assembly; gene family expansions; heavy metal tolerance; horizontal gene transfer; springtails