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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 from the choice interbreeding experiment. ‘P’ and ‘B’ indicate individuals from the Brazilian and Peruvian control populations. Individuals from the six mixed populations are labeled 1–6. For the COI region, all individuals in Group 1 were Brazilian, all individuals in Group 2 were Peruvian.
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ece32297-fig-0003: Non‐metric Multi‐Dimensional Scaling (nMDS) scatterplot using the ISSR data from the choice interbreeding experiment. ‘P’ and ‘B’ indicate individuals from the Brazilian and Peruvian control populations. Individuals from the six mixed populations are labeled 1–6. For the COI region, all individuals in Group 1 were Brazilian, all individuals in Group 2 were Peruvian.

Mentions: Two clearly defined groups were formed in the nMDS scatterplot from the ISSR data with all the Brazilian controls falling into Group 1 and all the Peruvian controls into Group 2 (Fig. 3). All the individuals that formed Group 1 had identical COI sequences to the Brazilian COI sequences from Taylor et al. (2011) and all those in Group 2 had identical sequences to the Peruvian sequences from the same study (Genbank accession numbers: Brazilian KU530108; Peruvian KU530109). No individuals were intermediate between the two groups and all individuals within a group had identical COI sequences (Fig. 3). This indicates that no hybrids were sampled in this experiment. When hybrid individuals from the no‐choice experiment were included in this analysis, they formed an intermediate group to the Brazilian and Peruvian groups in the nMDS plot similar to the hybrid group in Figure 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 from the choice interbreeding experiment. ‘P’ and ‘B’ indicate individuals from the Brazilian and Peruvian control populations. Individuals from the six mixed populations are labeled 1–6. For the COI region, all individuals in Group 1 were Brazilian, all individuals in Group 2 were Peruvian.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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

ece32297-fig-0003: Non‐metric Multi‐Dimensional Scaling (nMDS) scatterplot using the ISSR data from the choice interbreeding experiment. ‘P’ and ‘B’ indicate individuals from the Brazilian and Peruvian control populations. Individuals from the six mixed populations are labeled 1–6. For the COI region, all individuals in Group 1 were Brazilian, all individuals in Group 2 were Peruvian.
Mentions: Two clearly defined groups were formed in the nMDS scatterplot from the ISSR data with all the Brazilian controls falling into Group 1 and all the Peruvian controls into Group 2 (Fig. 3). All the individuals that formed Group 1 had identical COI sequences to the Brazilian COI sequences from Taylor et al. (2011) and all those in Group 2 had identical sequences to the Peruvian sequences from the same study (Genbank accession numbers: Brazilian KU530108; Peruvian KU530109). No individuals were intermediate between the two groups and all individuals within a group had identical COI sequences (Fig. 3). This indicates that no hybrids were sampled in this experiment. When hybrid individuals from the no‐choice experiment were included in this analysis, they formed an intermediate group to the Brazilian and Peruvian groups in the nMDS plot similar to the hybrid group in Figure 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.