Speciation by host-switching in pinyon Cinara (Insecta: Hemiptera: Aphididae)

Area of Science:

• Evolutionary Biology
• Insect Taxonomy
• Molecular Phylogenetics

Background:

• Parasite-host cospeciation is a key driver of insect diversification.
• Cinara aphids (Hemiptera: Aphididae) feed on conifers (Cupressaceae, Pinaceae) and often exhibit host fidelity.
• Previous research suggested Cinara speciation aligned with host plant evolution.

Purpose of the Study:

• Investigate the role of host-switching versus host fidelity in Cinara aphid speciation.
• Clarify the phylogenetic relationships of Cinara species associated with pinyon pines.
• Determine the relative importance of host fidelity and feeding site fidelity in aphid diversification.

Main Methods:

• Molecular phylogenetic analysis using mitochondrial cytochrome oxidase 1 and nuclear elongation factor 1-alpha DNA sequences.
• Phylogenetic reconstruction to infer evolutionary relationships among Cinara species.
• Comparative analysis of genetic divergence and host-plant associations.

Main Results:

• Host-switching played a significant role in the speciation of Cinara aphids, evidenced by the polyphyly of pinyon-feeding Cinara.
• Aphid species sharing feeding sites on different hosts were more closely related than those on the same host but different sites.
• Phylogenetic analysis suggested taxonomic revisions, including synonymizing Cinara rustica with C. edulis and identifying C. wahtolca as two distinct species.

Conclusions:

• Host-switching and feeding site fidelity are critical factors in Cinara aphid speciation and diversification.
• The findings challenge the traditional view of aphid evolution solely based on host plant taxonomy.
• This research provides a refined understanding of Cinara taxonomy and evolutionary history.