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Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments

View Article: PubMed Central - PubMed

ABSTRACT

There are many examples of cryptic species that have been identified through DNA‐barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.

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The median number of nymphs produced by breeding pairs for each interbreeding treatment under no‐choice conditions. Error bars represent the 25–75% range and lower case letters represent significant differences according to a Multiple Comparison of Mean Ranks test (P < 0.05) with the same letter representing no significant difference and different letters indicating where significant difference occurred. B indicates Brazilian population, P indicates the Peruvian population.
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ece32297-fig-0001: The median number of nymphs produced by breeding pairs for each interbreeding treatment under no‐choice conditions. Error bars represent the 25–75% range and lower case letters represent significant differences according to a Multiple Comparison of Mean Ranks test (P < 0.05) with the same letter representing no significant difference and different letters indicating where significant difference occurred. B indicates Brazilian population, P indicates the Peruvian population.

Mentions: Crosses of Peru♀ × Peru♂ produced an average of 32.9 nymphs (SE ± 3.06) and crosses of Brazil♀ × Brazil♂ produced an average of 26.9 nymphs (SE ± 5.33). An average of only 0.67 nymphs (SE ± 0.34) was produced by Brazil♀ × Peru♂ crosses and no offspring resulted from the reciprocal cross of Peru♀ × Brazil♂ (Fig. 1). There was an overall significant difference between all treatments (H = 54.05; P < 0.00001), where the within‐population treatments (Brazil♀ × Brazil♂; Peru♀ × Peru♂) produced significantly more offspring than both interpopulation treatments (Brazil♀ × Peru♂; Peru♀ × Brazil♂). Multiple comparisons of means revealed no significant difference between the two within‐population treatments.


Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
The median number of nymphs produced by breeding pairs for each interbreeding treatment under no‐choice conditions. Error bars represent the 25–75% range and lower case letters represent significant differences according to a Multiple Comparison of Mean Ranks test (P < 0.05) with the same letter representing no significant difference and different letters indicating where significant difference occurred. B indicates Brazilian population, P indicates the Peruvian population.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016637&req=5

ece32297-fig-0001: The median number of nymphs produced by breeding pairs for each interbreeding treatment under no‐choice conditions. Error bars represent the 25–75% range and lower case letters represent significant differences according to a Multiple Comparison of Mean Ranks test (P < 0.05) with the same letter representing no significant difference and different letters indicating where significant difference occurred. B indicates Brazilian population, P indicates the Peruvian population.
Mentions: Crosses of Peru♀ × Peru♂ produced an average of 32.9 nymphs (SE ± 3.06) and crosses of Brazil♀ × Brazil♂ produced an average of 26.9 nymphs (SE ± 5.33). An average of only 0.67 nymphs (SE ± 0.34) was produced by Brazil♀ × Peru♂ crosses and no offspring resulted from the reciprocal cross of Peru♀ × Brazil♂ (Fig. 1). There was an overall significant difference between all treatments (H = 54.05; P < 0.00001), where the within‐population treatments (Brazil♀ × Brazil♂; Peru♀ × Peru♂) produced significantly more offspring than both interpopulation treatments (Brazil♀ × Peru♂; Peru♀ × Brazil♂). Multiple comparisons of means revealed no significant difference between the two within‐population treatments.

View Article: PubMed Central - PubMed

ABSTRACT

There are many examples of cryptic species that have been identified through DNA&#8208;barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.

No MeSH data available.


Related in: MedlinePlus