What were the authors trying to test, and what predictions did they make?
The authors were assessing the genetic diversity and relatedness in the critically endangered species hawk Buteu ridgwayi. The island population of birds is expected to exhibit a lower genetic variation than mainland populations. This is because there is reduced gene flow, smaller population sizes and increased genetic drift due to isolation. The island birds also likely suffer from inbreeding depression.
What, exactly, did the authors do?
The authors collected samples, and monitored nests and breeding pairs over four years. Blood was collected from 149 Ridgway’s Hawks. Fourteen microsatellite loci were tested to examine allelic variation. The program Bottleneck was used to test for the presence of a genetic bottleneck. Alrequin was used to calculate the observed heterozygosity, expected heterozygosity, and number of alleles. The relatedness was determined used a program called Kin Group.
What did the authors find (i.e, what were their data)?
The allele frequencies ranged from 0.0069 to 0.4960. The observed heterozygosity across loci ranged from 0.521 to 0.884. Relatedness coefficients of the seven sampled breeding
pairs ranged from -0.09 to 0.55. There was no structure present, all of the samples came from one genetic population. A significant excess of heterozygotes was found.
How did the authors interpret their findings?
The results from the study show that the population underwent a recent genetic bottleneck, had a high level of heterozygosity, and occurred inbreeding. The significant excess of heterozygotes indicates a recent genetic bottleneck. The relatedness analysis verified the presence of inbreeding. Island avian populations are of great concern, because they have a higher risk of extinction than mainland animals. These island birds are more susceptible to extinction primarily due to human caused habitat loss and introduced species.
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