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Graduation Term

Summer 2025

Degree Name

Master of Science (MS)

Department

School of Biological Sciences

Committee Chair

Pirmin Nietlisbach

Committee Member

Charles F Thompson

Committee Member

Scott K Sakaluk

Committee Member

William L Perry

Abstract

There are many mating strategies in nature, one of which is social monogamy, in which a male and female mate and raise young together in a pair bond. In social monogamy, it is common for animals to mate with individuals outside of the pair bond. In birds, matings outside the pair bond can result in a mixed brood containing extra-pair young. This poses an issue for males, as paternity loss to other males results in decreased fitness. In some species, males respond to paternity loss by lowering their parental care to nestlings, which is usually measured in terms of provisioning effort. However, in other species, there is no response to a loss of paternity. We tested whether the northern house wren males changed provisioning effort in an oak savannah habitat located in central Illinois. We recorded male provisioning effort with video cameras placed outside nestboxes. We took blood samples from all house wren adults and nestlings to determine paternity by comparing microsatellites. Of the 544 nestlings between the 104 nests, there were 32 extra-pair young from 19 nests, which comprised 5.9% of all nestlings across 18.3% of all nests. Male provisioning rate was not explained by paternity within a nest, contrary to our expectations, as previous experiments at our field site found that males abandoned the nest more often when exposed to an artificial paternity threat. However, females did respond to low rates of male provisioning and compensated by feeding more often. Males may have kept unchanged provisioning rates because most nests containing extra-pair paternity only had 1 extra-pair nestling, so reduction of provisioning rate mostly harms offspring sired by that male. An alternative explanation is that males were unable to detect paternity threats and thus did not have access to a reliable cue about their paternity. The relationship between paternal effort and paternity still proves enigmatic to generalize across species and populations, despite extensive efforts. This study provides an additional perspective to this discussion.

Access Type

Thesis-ISU Access Only

DOI

https://doi.org/10.30707/ETD.1763755358.612976

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