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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.


Female egg laying. (A) Females eating Eriodictyon trichocalyx laid more eggs than females eating Eriodictyon crassifolium (t253 = 4.2137, P < 0.010) and as a result (B) produced more hatchlings (Mann–Whitney U‐test = 453.5, P = 0.040). (C) Females eating Eriodictyon trichocalyx also laid fertilized eggs for a longer duration than those eating E. crassifolium (Mann–Whitney U‐test = 127.0, P = 0.001).
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ece31658-fig-0004: Female egg laying. (A) Females eating Eriodictyon trichocalyx laid more eggs than females eating Eriodictyon crassifolium (t253 = 4.2137, P < 0.010) and as a result (B) produced more hatchlings (Mann–Whitney U‐test = 453.5, P = 0.040). (C) Females eating Eriodictyon trichocalyx also laid fertilized eggs for a longer duration than those eating E. crassifolium (Mann–Whitney U‐test = 127.0, P = 0.001).

Mentions: Females that ate sticky E. trichocalyx laid more eggs than females on hairy E. crassifolium (Fig. 4A: t253 = 4.2137, P < 0.001). As a result, these same females produced far more hatchlings (Fig. 4B, Mann–Whitney U‐test = 453.5, P = 0.040). Females eating E. trichocalyx laid fertilized eggs for a longer time span than those on E. crassifolium (Fig. 4C, Mann–Whitney U‐test = 127.0, P = 0.001).


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

Gould K, Wilson P - Ecol Evol (2015)

Female egg laying. (A) Females eating Eriodictyon trichocalyx laid more eggs than females eating Eriodictyon crassifolium (t253 = 4.2137, P < 0.010) and as a result (B) produced more hatchlings (Mann–Whitney U‐test = 453.5, P = 0.040). (C) Females eating Eriodictyon trichocalyx also laid fertilized eggs for a longer duration than those eating E. crassifolium (Mann–Whitney U‐test = 127.0, P = 0.001).
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4588663&req=5

ece31658-fig-0004: Female egg laying. (A) Females eating Eriodictyon trichocalyx laid more eggs than females eating Eriodictyon crassifolium (t253 = 4.2137, P < 0.010) and as a result (B) produced more hatchlings (Mann–Whitney U‐test = 453.5, P = 0.040). (C) Females eating Eriodictyon trichocalyx also laid fertilized eggs for a longer duration than those eating E. crassifolium (Mann–Whitney U‐test = 127.0, P = 0.001).
Mentions: Females that ate sticky E. trichocalyx laid more eggs than females on hairy E. crassifolium (Fig. 4A: t253 = 4.2137, P < 0.001). As a result, these same females produced far more hatchlings (Fig. 4B, Mann–Whitney U‐test = 453.5, P = 0.040). Females eating E. trichocalyx laid fertilized eggs for a longer time span than those on E. crassifolium (Fig. 4C, Mann–Whitney U‐test = 127.0, P = 0.001).

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.