The Baltimore Orioles and Black-backed Orioles species complex has conflicting evidence in support of each being their own species and in support of them being the same species. Review the evidence below for each hypothesis, then, using that evidence, explain whether they should be classified as distinct or the same species based on each species concept. Then, using the overall evidence, decide whether to classify them as the same or different species. Genetic Information (In the Species Concepts lab, we used a "controversial" 10% cutoff. A more realistic cutoff might be 1%. Let's use a 1% cutoff for this activity.) Sequence Differences Baltimore Oriole vs Black- backed Oriole Cytochrome b 0.26% Control region 0.74% 2A. Based on the genetic information above, should the Baltimore Oriole and Black-backed Oriole be classified as one species or two species?
Genetic Recombination
Recombination is crucial to this process because it allows genes to be reassorted into diverse combinations. Genetic recombination is the process of combining genetic components from two different origins into a single unit. In prokaryotes, genetic recombination takes place by the unilateral transfer of deoxyribonucleic acid. It includes transduction, transformation, and conjugation. The genetic exchange occurring between homologous deoxyribonucleic acid sequences (DNA) from two different sources is termed general recombination. For this to happen, an identical sequence of the two recombining molecules is required. The process of genetic exchange which occurs in eukaryotes during sexual reproduction such as meiosis is an example of this type of genetic recombination.
Microbial Genetics
Genes are the functional units of heredity. They transfer characteristic information from parents to the offspring.
The Baltimore Oriole and the Black-backed Oriole may be sister taxa, according to a recent evolutionary analysis of orioles from the New World. A single representative of each species in the genus was used for the survey's analysis of mitochondrial DNA (mtDNA).
When mtDNA sequences from 20 Baltimore Orioles and 15 Black backed Orioles were analyzed. The average sequence divergences for both cytochrome b (cyt b) and the regulatory region point to a likely late Pleistocene split, suggesting that the two species have only recently separated. There is one fixed base-pair difference between the species in cyt b and another in the control region despite this recent divergence, indicating that one or both species may have experienced a bottleneck during or since speciation. According to this molecular evidence of recent divergence, the male plumage variations between Baltimore and Black-backed Orioles evolved relatively quickly.
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