Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites?
Hamilton & Orians (1965) stated that the non-parasitic ancestor of cowbirds accelerated its incubation period and nestling growth. Later, by comparing cowbirds with nesting birds, it was suggested that those characteristics, together with small eggs with thicker eggshell, were adaptations. When...
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2011
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10754377_v22_n4_p553_ManuelaPujol http://hdl.handle.net/20.500.12110/paper_10754377_v22_n4_p553_ManuelaPujol |
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paper:paper_10754377_v22_n4_p553_ManuelaPujol2023-06-08T16:05:17Z Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? Mermoz, Myriam Emilia Adaptations Allometric equation Ancestor reconstruction Brood parasites Cowbirds Egg mass Exaptations Incubation period Molothrus Nestling asymptotic body mass Hamilton & Orians (1965) stated that the non-parasitic ancestor of cowbirds accelerated its incubation period and nestling growth. Later, by comparing cowbirds with nesting birds, it was suggested that those characteristics, together with small eggs with thicker eggshell, were adaptations. When these hypotheses were tested considering the characteristics of the group in which cowbirds evolved, i.e. the "grackles and allies", it was found that only the thicker eggshell was a plausible adaptation. Moreover, nesting grackles and allies showed the same reproductive patterns as cowbirds (shorter incubation periods, faster nestling growth, and smaller eggs than those predicted by general allometric equations). In the present study, we tested whether small eggs with short incubation periods and nestlings with accelerated growth evolved in the ancestor of grackles and allies. For all the traits tested, we reconstructed ancestral states and built prediction intervals generated with independent variables that were allometrically related to them. Except for accelerated growth, we applied two evolutionary models incorporating outgroups in three steps. We found that the short incubation period and the faster nestling growth never evolved in the ancestor of grackles and allies. In most ancestor reconstructions, neither egg mass nor female body mass changed. However, when it changed, it increased both egg and female masses. The prediction intervals indicated that those increases did not imply an allometric change in size. Consequently, neither a decrease in egg mass nor an acceleration in nestling development and incubation period are considered characteristics that predisposed cowbirds to become brood parasites. © The Neotropical Ornithological Society. Fil:Mermoz, M.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10754377_v22_n4_p553_ManuelaPujol http://hdl.handle.net/20.500.12110/paper_10754377_v22_n4_p553_ManuelaPujol |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Adaptations Allometric equation Ancestor reconstruction Brood parasites Cowbirds Egg mass Exaptations Incubation period Molothrus Nestling asymptotic body mass |
| spellingShingle |
Adaptations Allometric equation Ancestor reconstruction Brood parasites Cowbirds Egg mass Exaptations Incubation period Molothrus Nestling asymptotic body mass Mermoz, Myriam Emilia Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? |
| topic_facet |
Adaptations Allometric equation Ancestor reconstruction Brood parasites Cowbirds Egg mass Exaptations Incubation period Molothrus Nestling asymptotic body mass |
| description |
Hamilton & Orians (1965) stated that the non-parasitic ancestor of cowbirds accelerated its incubation period and nestling growth. Later, by comparing cowbirds with nesting birds, it was suggested that those characteristics, together with small eggs with thicker eggshell, were adaptations. When these hypotheses were tested considering the characteristics of the group in which cowbirds evolved, i.e. the "grackles and allies", it was found that only the thicker eggshell was a plausible adaptation. Moreover, nesting grackles and allies showed the same reproductive patterns as cowbirds (shorter incubation periods, faster nestling growth, and smaller eggs than those predicted by general allometric equations). In the present study, we tested whether small eggs with short incubation periods and nestlings with accelerated growth evolved in the ancestor of grackles and allies. For all the traits tested, we reconstructed ancestral states and built prediction intervals generated with independent variables that were allometrically related to them. Except for accelerated growth, we applied two evolutionary models incorporating outgroups in three steps. We found that the short incubation period and the faster nestling growth never evolved in the ancestor of grackles and allies. In most ancestor reconstructions, neither egg mass nor female body mass changed. However, when it changed, it increased both egg and female masses. The prediction intervals indicated that those increases did not imply an allometric change in size. Consequently, neither a decrease in egg mass nor an acceleration in nestling development and incubation period are considered characteristics that predisposed cowbirds to become brood parasites. © The Neotropical Ornithological Society. |
| author |
Mermoz, Myriam Emilia |
| author_facet |
Mermoz, Myriam Emilia |
| author_sort |
Mermoz, Myriam Emilia |
| title |
Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? |
| title_short |
Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? |
| title_full |
Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? |
| title_fullStr |
Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? |
| title_full_unstemmed |
Do life-history traits in the ancestor of Cowbirds (Molothrus spp.) predispose them to become brood parasites? |
| title_sort |
do life-history traits in the ancestor of cowbirds (molothrus spp.) predispose them to become brood parasites? |
| publishDate |
2011 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10754377_v22_n4_p553_ManuelaPujol http://hdl.handle.net/20.500.12110/paper_10754377_v22_n4_p553_ManuelaPujol |
| work_keys_str_mv |
AT mermozmyriamemilia dolifehistorytraitsintheancestorofcowbirdsmolothrusspppredisposethemtobecomebroodparasites |
| _version_ |
1768544561615863808 |