Question
Hi there! Could you please help me answer these 2 questions? I need them today. Thank you so much in advance! (I have attached the article below for reference.)
1. We can see clines as a result of secondary contact. Look at the hybrid zone widths reported on pg. 1354. Assuming no difference in dispersal ability, what can you infer about differences in selection in hybrid zone A and B?
2. Are all types of hybrid pairings equally likely to result in successful offspring? Consider
both the lab experiments and field experiments.
Vol 437127 October 2005 doi: 10.1038/nature04004 LETTERS Reinforcement drives rapid allopatric speciation Conrad J. Hoskin', Megan Higgie', Keith R. McDonald2 & Craig Moritz Allopatric speciation results from geographic isolation between Although the role of reinforcing natural selection in driving populations. In the absence of gene flow, reproductive isolation allopatric speciation within a lineage has received little attention arises gradually and incidentally as a result of mutation, genetic role in the final stages of speciation between divergent sister drift and the indirect effects of natural selection driving local lineages has had a long and contentious history-some consider that adaptation' s. In contrast, speciation by reinforcement is driven there are compelling examples, whereas others argue that the directly by natural selection against maladaptive hybridization' empirical evidence is generally inconclusive Uncertainty remains because strict criteria must be satisfied to demonstrate the process of This gives individuals that choose the traits of their own lineag greater fitness, potentially leading to rapid speciation between the reinforcement unambiguously first, heterospecific matings occur in lineages' 4. Reinforcing natural selection on a population of one of the field; second, there is selection against hybridization; third, the lineages in a mosaic contact zone could also result in diver- displacement of a trait is perceived by the other sex; fourth, variation gence of the population from the allopatric range of its own n the trait s heritable and responds to selection; and last, displace lineage outside the zone re. Here we test this with molecular ment has not occurred for other reasons, such as ecological diver data, experimental crosses, field measurements and mate choice gence. Demonstrating that this process can complete speciation experiments in a mosaic contact zone between two lineage o f a requires showing that it has resulted in significant reproductive rainforest frog. We show that reinforcing natural selection has solation be ween the lineages. Further, evidence for forcement resulted in significant premating isolation of a population in the pelling thin a well-corroborated historical biogeo S mos contact zone not only fr graphic fra om the other neage but also, incidentally, mework from the close related main range of its own linea Thus we The green-eyed tree-frog Litoria genimacula is a stream-breeding show the potential for reinforcement to drive rapid allopatric hylid frog common in rainforest throughout the Wet Tropics' region of northeast Queensland, Australia. Like many other Wet Tropics speciation. Figure 1 Distribution of the N (pale shading) and S (dark shading lineages ofL.genimaculata. a, The distribution of Nand S and a tree showing genetic divergence (percentage) and the number of individuals with each haplotype b, An Pacific enlargement of the region within the rectangle in Ocean a, showing the mosaic contact between the N and S lineages. The is population shares haplotype with 0.1% net divergence overall) with neat populations from the main range of the S lineag a) but is currently isolated from them (population subdivision statistic Fst 0.20, P y contrast, the N populations are 0.00 Barron River continuous and genetically connected (north 13.1% versus south of Barron River F. 0.0 0.60) through the mosaic contact. 2 is 3 is Northeast 2 is Queensland 4 km 0 50 km 'School of Integrative Biology, University of Queensland, St Lucia, Queensland 4072, Australia. 2Queensland Parks and wildlife Service, Po Box 97s, Atherton, Queensland 4883, Australia. Mu seum of Vertebrate Zoology, University of California, Berkeley, California 94720, USA. 1353 2005 Nature Publishing Group
Explanation / Answer
A. As, mentioned in the article, females of the southern lineage showed significantly better choice at selection of mate. They could distinguish between the calls more,than the northern females. They, selected from within their own species and this would decrease the hybridization/ hybrid zone. So, the differences in the two hybrid zones would occur.
B. If speciation have already occurred, other laboratory conditions, hybridization is still possible i.e offspring production would be successful but the resulting offspring would be sterile. All types of hybrid pairings are likely to result in successful offspring in this case. This is true for any interspecific organism. However, if only the subspecies are different and mating occurs, within the same species, the resulting offspring would not be sterile.
