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Lack of evolution in a leaf beetle that lives on two contrasting host plants.

Gould K, Wilson P - Ecol Evol (2015)

Bottom Line: Males did not prefer to mate with females from E. trichocalyx.Females from E. crassifolium did prefer males from E. trichocalyx over males from E. crassifolium, but did not lay more eggs as a result of these matings.We conclude that the beetle populations we studied have not differentiated based on their host plants and may not have even adapted to the better host.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology California State University Northridge California 91330-8303.

ABSTRACT
The interactions between plant-eating insects and their hosts have shaped both the insects and the plants, driving evolution of plant defenses and insect specialization. The leaf beetle Trirhabda eriodictyonis (Chrysomelidae) lives on two shrubs with differing defenses: Eriodictyon crassifolium has hairy leaves, whereas E. trichocalyx has resinous leaves. We tested whether these beetles have differentiated onto the two host plants, and if not, whether the beetles prefer the better host plant and prefer mates who are from that host plant. In feeding tests, adult beetles strongly preferred eating E. trichocalyx regardless of which host they came from. In addition, females laid more eggs if they ate E. trichocalyx than E. crassifolium. So, E. trichocalyx is generally the better host. However, beetle mate preference was not in line with food choice. Males did not prefer to mate with females from E. trichocalyx. Females from E. crassifolium did prefer males from E. trichocalyx over males from E. crassifolium, but did not lay more eggs as a result of these matings. We conclude that the beetle populations we studied have not differentiated based on their host plants and may not have even adapted to the better host. Although to humans these host plant defenses differ dramatically, signs that they have caused evolution in the beetles are lacking. The case of T. eriodictyonis stands counter to many other studies that have seen the differentiation of ecotypes and/or adaptive coordination of an herbivore's life cycle based on host plant differences.

No MeSH data available.


Egg production, by mating treatment. (A) Females that ate Eriodictyon crassifolium and mated with males that had eaten Eriodictyon trichocalyx produced the fewest hatchlings among treatments, although the difference was not statistically significant (Kruskal–Wallis K3 = 5.130, P = 0.162). (B) These same females laid their eggs faster than females in all other treatments (Kruskal–Wallis K3 = 11.814, P = 0.008). Bars with a similar letter were not significantly different by Dwass‐Steel‐Critchlow‐Fligner pairwise comparisons.
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ece31658-fig-0005: Egg production, by mating treatment. (A) Females that ate Eriodictyon crassifolium and mated with males that had eaten Eriodictyon trichocalyx produced the fewest hatchlings among treatments, although the difference was not statistically significant (Kruskal–Wallis K3 = 5.130, P = 0.162). (B) These same females laid their eggs faster than females in all other treatments (Kruskal–Wallis K3 = 11.814, P = 0.008). Bars with a similar letter were not significantly different by Dwass‐Steel‐Critchlow‐Fligner pairwise comparisons.

Mentions: Females from all treatments produced similar total numbers of hatchlings (Fig. 5A, Kruskal–Wallis K3 = 5.130, P = 0.162). Graphically, fewer eggs seemed to be produced by females from E. crassifolium that mated with males from E. trichocalyx, but the difference was not statistically significant.


Lack of evolution in a leaf beetle that lives on two contrasting host plants.

Gould K, Wilson P - Ecol Evol (2015)

Egg production, by mating treatment. (A) Females that ate Eriodictyon crassifolium and mated with males that had eaten Eriodictyon trichocalyx produced the fewest hatchlings among treatments, although the difference was not statistically significant (Kruskal–Wallis K3 = 5.130, P = 0.162). (B) These same females laid their eggs faster than females in all other treatments (Kruskal–Wallis K3 = 11.814, P = 0.008). Bars with a similar letter were not significantly different by Dwass‐Steel‐Critchlow‐Fligner pairwise comparisons.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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ece31658-fig-0005: Egg production, by mating treatment. (A) Females that ate Eriodictyon crassifolium and mated with males that had eaten Eriodictyon trichocalyx produced the fewest hatchlings among treatments, although the difference was not statistically significant (Kruskal–Wallis K3 = 5.130, P = 0.162). (B) These same females laid their eggs faster than females in all other treatments (Kruskal–Wallis K3 = 11.814, P = 0.008). Bars with a similar letter were not significantly different by Dwass‐Steel‐Critchlow‐Fligner pairwise comparisons.
Mentions: Females from all treatments produced similar total numbers of hatchlings (Fig. 5A, Kruskal–Wallis K3 = 5.130, P = 0.162). Graphically, fewer eggs seemed to be produced by females from E. crassifolium that mated with males from E. trichocalyx, but the difference was not statistically significant.

Bottom Line: Males did not prefer to mate with females from E. trichocalyx.Females from E. crassifolium did prefer males from E. trichocalyx over males from E. crassifolium, but did not lay more eggs as a result of these matings.We conclude that the beetle populations we studied have not differentiated based on their host plants and may not have even adapted to the better host.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology California State University Northridge California 91330-8303.

ABSTRACT
The interactions between plant-eating insects and their hosts have shaped both the insects and the plants, driving evolution of plant defenses and insect specialization. The leaf beetle Trirhabda eriodictyonis (Chrysomelidae) lives on two shrubs with differing defenses: Eriodictyon crassifolium has hairy leaves, whereas E. trichocalyx has resinous leaves. We tested whether these beetles have differentiated onto the two host plants, and if not, whether the beetles prefer the better host plant and prefer mates who are from that host plant. In feeding tests, adult beetles strongly preferred eating E. trichocalyx regardless of which host they came from. In addition, females laid more eggs if they ate E. trichocalyx than E. crassifolium. So, E. trichocalyx is generally the better host. However, beetle mate preference was not in line with food choice. Males did not prefer to mate with females from E. trichocalyx. Females from E. crassifolium did prefer males from E. trichocalyx over males from E. crassifolium, but did not lay more eggs as a result of these matings. We conclude that the beetle populations we studied have not differentiated based on their host plants and may not have even adapted to the better host. Although to humans these host plant defenses differ dramatically, signs that they have caused evolution in the beetles are lacking. The case of T. eriodictyonis stands counter to many other studies that have seen the differentiation of ecotypes and/or adaptive coordination of an herbivore's life cycle based on host plant differences.

No MeSH data available.