Commensalism and hybrid speciation: how parental genomes affect exploration in the Italian sparrow (Passer italiae)
(2025) BION02 20241Degree Projects in Biology
- Abstract
- Hybridization may generate novel trait values and combinations, enabling hybrid lineages to exploit new niches. While phenotypic differences among hybrids and parents are well characterized, it is less well understood if behaviors are likely to be intermediate, mosaic, or transgressive, outside the parental ranges of values. To address how behavioral traits evolve in hybrid lineages, we use the homoploid hybrid Italian sparrow (Passer italiae), whose parental species are the commensal house sparrow (P. domesticus) and the non-commensal Spanish sparrow (P. hispaniolensis). We hypothesize that the different ecological strategies of the parental species correspond to differences in heritable behavioral phenotypes, such as exploration. We... (More)
- Hybridization may generate novel trait values and combinations, enabling hybrid lineages to exploit new niches. While phenotypic differences among hybrids and parents are well characterized, it is less well understood if behaviors are likely to be intermediate, mosaic, or transgressive, outside the parental ranges of values. To address how behavioral traits evolve in hybrid lineages, we use the homoploid hybrid Italian sparrow (Passer italiae), whose parental species are the commensal house sparrow (P. domesticus) and the non-commensal Spanish sparrow (P. hispaniolensis). We hypothesize that the different ecological strategies of the parental species correspond to differences in heritable behavioral phenotypes, such as exploration. We assess exploratory behavior using three independent lineages of Italian sparrow from Crete, Corsica, and Sicily, differing in genetic contribution from the two parental species, as well as the two parental species and male F1 hybrids. Some individuals failed to perform any exploratory behavior during the trial, though all origin groups were equally likely to explore. We find that house sparrows were more active than Spanish sparrows. Interestingly, females from all three Italian lineages were similar in activity level to house sparrow females, while males from the Corsican and Sicilian lineages were similar to male Spanish sparrows, and males of the Cretan lineage were more active than all other groups. Across measurements, the most important predictor of behavior is the interaction of origin with sex, with a general tendency for house sparrows to be more exploratory than Spanish sparrows, and Italian sparrows being intermediate. In conclusion, we show that Italian sparrows, which are typically human commensal, have exploratory phenotypes intermediate between those of the parental species, with a tendency for extreme exploration behaviors in the Cretan lineage. (Less)
- Popular Abstract
- Urban explorers: hybrid sparrows in human environments
Hybridization has historically been viewed as an evolutionary “mistake,” but research in recent decades has shown that it can also be an important creative force. Traits from parental species can combine in new ways in their hybrid offspring, potentially allowing those offspring to use new habitats and sometimes evolve into new species. This process may have occurred in the establishment of the hybrid Italian sparrow as an independent species. We compared exploration in Italian sparrows and their parental species, as this behavioral trait may relate to the ability to live in a novel human environment.
Italian sparrows arose from hybridization between house sparrows (P.... (More) - Urban explorers: hybrid sparrows in human environments
Hybridization has historically been viewed as an evolutionary “mistake,” but research in recent decades has shown that it can also be an important creative force. Traits from parental species can combine in new ways in their hybrid offspring, potentially allowing those offspring to use new habitats and sometimes evolve into new species. This process may have occurred in the establishment of the hybrid Italian sparrow as an independent species. We compared exploration in Italian sparrows and their parental species, as this behavioral trait may relate to the ability to live in a novel human environment.
Italian sparrows arose from hybridization between house sparrows (P. domesticus) and Spanish sparrows (P. hispaniolensis) during the spread of human agriculture around 6,000 years ago, and now exist as an independent species. House sparrows and Italian sparrows are human-commensal, living alongside humans, while Spanish sparrows are not, preferring to live away from human settlements. These different ecological strategies likely correspond to differences in behavioral traits such as exploration. We expect that house sparrows, being human-commensal, will be highly explorative, and Spanish sparrows, being non-commensal, will explore the least. If Italian sparrows consistently inherit stronger, house-sparrow-like exploratory tendencies, it would suggest that this behavioral trait is important for their ability to live alongside humans.
It is possible to identify patterns in the way exploration is inherited in Italian sparrows because separate lineages have arisen on different Mediterranean islands, and each lineage has a different proportion of genes from the parental species. Italian sparrows from Crete are approximately 75% house sparrow, those from Corsica are approximately 50%, and those from Sicily are approximately 25%. We tested whether Italian sparrows inherit exploration in proportion to their respective house sparrow ancestry, or whether a different pattern might emerge.
Exploration was compared among six different origin groups: house sparrows, Spanish sparrows, three lineages of Italian sparrows, and first-generation house x Spanish sparrow hybrids. We scored exploration in these groups using a novel environment test. Each bird was released into a modified aviary with different features for them to visit, and their behavior in this environment was recorded for 15 minutes. From this footage, we selected six different measurements of exploration to use in comparing our six origin groups.
We found that, as expected, house sparrows tended to have the highest exploration across measurements, while Spanish sparrows tended to have the lowest. Italian sparrows generally had intermediate exploration in relative proportion to their house sparrow DNA. Male Italian sparrows from Crete, however, often had even higher exploration scores than house sparrows. This extreme exploration may arise from novel combinations of parental genes, just like phenotypes outside of both parental ranges commonly arise in hybrids. The intermediate exploration of the Corsican and Sicilian lineages was similar to that of first-generation house x Spanish sparrow hybrids. This similarity suggests that natural selection has not acted very strongly on this trait in the generations it took for Italian sparrows to become an independent species. The ability of an animal to be human-commensal may also depend upon multiple traits beyond just exploratory behavior, such as sociality and physiology. Still, most Italian sparrows explored more than non-commensal Spanish sparrows, so it is possible that Italian sparrows’ elevated exploratory behavior contributes to their ability to live alongside humans even if this trait is not the sole reason for this ability.
Master’s Degree Project in Animal Ecology 45 credits 2024
Department of Biology, Lund University
Advisor: Anna Runemark
Co-advisor Rachel Steward (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9185112
- author
- Duhé Jones, Samantha
- supervisor
-
- Anna Runemark LU
- Rachel Steward LU
- organization
- course
- BION02 20241
- year
- 2025
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9185112
- date added to LUP
- 2025-02-13 08:56:28
- date last changed
- 2025-02-13 08:56:28
@misc{9185112,
abstract = {{Hybridization may generate novel trait values and combinations, enabling hybrid lineages to exploit new niches. While phenotypic differences among hybrids and parents are well characterized, it is less well understood if behaviors are likely to be intermediate, mosaic, or transgressive, outside the parental ranges of values. To address how behavioral traits evolve in hybrid lineages, we use the homoploid hybrid Italian sparrow (Passer italiae), whose parental species are the commensal house sparrow (P. domesticus) and the non-commensal Spanish sparrow (P. hispaniolensis). We hypothesize that the different ecological strategies of the parental species correspond to differences in heritable behavioral phenotypes, such as exploration. We assess exploratory behavior using three independent lineages of Italian sparrow from Crete, Corsica, and Sicily, differing in genetic contribution from the two parental species, as well as the two parental species and male F1 hybrids. Some individuals failed to perform any exploratory behavior during the trial, though all origin groups were equally likely to explore. We find that house sparrows were more active than Spanish sparrows. Interestingly, females from all three Italian lineages were similar in activity level to house sparrow females, while males from the Corsican and Sicilian lineages were similar to male Spanish sparrows, and males of the Cretan lineage were more active than all other groups. Across measurements, the most important predictor of behavior is the interaction of origin with sex, with a general tendency for house sparrows to be more exploratory than Spanish sparrows, and Italian sparrows being intermediate. In conclusion, we show that Italian sparrows, which are typically human commensal, have exploratory phenotypes intermediate between those of the parental species, with a tendency for extreme exploration behaviors in the Cretan lineage.}},
author = {{Duhé Jones, Samantha}},
language = {{eng}},
note = {{Student Paper}},
title = {{Commensalism and hybrid speciation: how parental genomes affect exploration in the Italian sparrow (Passer italiae)}},
year = {{2025}},
}