![\"Mottled](\"http:\/\/pages.vassar.edu\/sensoryecology\/files\/2016\/05\/eggs.jpg\")
<\/a>Mottled cowbird egg among host robin eggs.
http:\/\/www.pbs.org\/wgbh\/nova\/sciencenow\/0407\/03-moth-01.html<\/p><\/div>\n
This study tested three different hypothesis.\u00a0 The first two were previously proposed hypotheses:\u00a0 There should be minimal variation within a single clutch and there should be high variation between the eggs of females within species.\u00a0 The authors also proposed and tested a new hypothesis that there would be more variation among eggs of host species than of species that are not subject to brood parasitism.\u00a0 To test these hypothesis, they examined the eggs of 40 different Australian species and analyzed pattern and color differences among these species.<\/p>\n
There was no significant difference found in color between host and non-host species.\u00a0 They did, however, find larger differences in egg pattern in hosts.\u00a0 Among host species that shared the same parasite there were smaller pattern differences.\u00a0 The eggs of host species had significantly more variation in egg pattern than those of non-host species.\u00a0 While two of the hypotheses were supported by the results, the first hypothesis, that there would be minimal variation within a clutch, was not.\u00a0 Instead, the authors found higher within-clutch variation in host species.<\/p>\n
This experiment shows, quite possibly for the first time, that pairs of host species have diverged more in egg pattern than pairs of non-host species.\u00a0 It also demonstrates that divergence in characteristics is smaller than hosts that share a parasite.\u00a0 This result was expected as many species that share a parasite are often closely related and would therefore potentially have more similar eggs.\u00a0 The results of this study provide substantial evidence that brood parasitism is a driving force in the evolution of egg diversity. \u00a0One very large challenge of evolutionary biology is explaining and understanding observed diversity patterns, and these results have now contributed to our understanding of diversity among quite a few species.<\/p>\n
Reference:<\/p>\n
Medina, I., Troscianko, J., Stevens, M., Langmore, N.E. (2016). Brood parasitism is linked to egg pattern diversity within and among species of Australian passerines. The American Naturalist, 187, 351-362.<\/p>\n","protected":false},"excerpt":{"rendered":"
For many avian species, raising young is a very large investment.\u00a0 Instead of doing it themselves, some birds use a method called brood parasitism, leaving an egg or multiple eggs in a host bird\u2019s nest to be raised there.\u00a0 This … Continue reading