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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.

No MeSH data available.


Non‐metric Multi‐Dimensional Scaling (nMDS) scatterplot using the ISSR data for hybrid offspring and the parents of hybrid offspring. Hybrids share an identical COI profile to their mothers and are intermediate to their parents in the MDS plot. B♀ indicates Brazilian mothers, P♂ the Peruvian fathers and H the hybrid offspring.
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ece32297-fig-0002: Non‐metric Multi‐Dimensional Scaling (nMDS) scatterplot using the ISSR data for hybrid offspring and the parents of hybrid offspring. Hybrids share an identical COI profile to their mothers and are intermediate to their parents in the MDS plot. B♀ indicates Brazilian mothers, P♂ the Peruvian fathers and H the hybrid offspring.

Mentions: A total of 16 hybrid individuals were produced, 12 of which were analyzed using genetic techniques to confirm that they were true hybrids (see Genetic analysis for genetics methods). All hybrid individuals from the Brazil♀ × Peru♂ crosses shared the identical Brazilian COI sequence from Taylor et al. (2011) and formed a third group intermediate to the Brazilian and Peruvian parents in the nMDS from the ISSR data (Fig. 2).


Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
Non‐metric Multi‐Dimensional Scaling (nMDS) scatterplot using the ISSR data for hybrid offspring and the parents of hybrid offspring. Hybrids share an identical COI profile to their mothers and are intermediate to their parents in the MDS plot. B♀ indicates Brazilian mothers, P♂ the Peruvian fathers and H the hybrid offspring.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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

ece32297-fig-0002: Non‐metric Multi‐Dimensional Scaling (nMDS) scatterplot using the ISSR data for hybrid offspring and the parents of hybrid offspring. Hybrids share an identical COI profile to their mothers and are intermediate to their parents in the MDS plot. B♀ indicates Brazilian mothers, P♂ the Peruvian fathers and H the hybrid offspring.
Mentions: A total of 16 hybrid individuals were produced, 12 of which were analyzed using genetic techniques to confirm that they were true hybrids (see Genetic analysis for genetics methods). All hybrid individuals from the Brazil♀ × Peru♂ crosses shared the identical Brazilian COI sequence from Taylor et al. (2011) and formed a third group intermediate to the Brazilian and Peruvian parents in the nMDS from the ISSR data (Fig. 2).

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.

No MeSH data available.