Pelage Variation and Morphometrics of Closely RelatedCallithrixMarmoset Species and Their Hybrids
Authors: Malukiewicz Joanna , Warren Kerryn , Boere Vanner , Bandeira Illaira LC , Curi Nelson HA , das Dores Fabio T , Fitorra Lilian S , Furuya Haroldo R , Igayara Claudia S , Milanelo Liliane , Moreira Silvia B , Molina Camila V , Nardi Marcello S , Nicola Patricia A , Passamani Marcelo , Pedro Valeria S , Pereira Luiz CM , Petri Bruno , Pissinatti Alcides , Quirino Adriana Alves , Rogers Jeffrey , Ruiz-Miranda Carlos R , Silva Daniel L , Silva Ita O , Silva Monique OM , Summa Juliana L , Zwarg Ticiana , Ackermann Rebecca R 
Published: January 2023

Background

Hybrids are expected to show greater phenotypic variation than their parental species, yet how hybrid phenotype expression varies with genetic distances in closely-related parental species remains surprisingly understudied. Here we study pelage and morphometric trait variation in anthropogenic hybrids vailable at the end of the article between four species of BrazilianCallithrixmarmosets, a relatively recent primate radiation. Marmoset species are distinguishable by pelage phenotype and morphological specializations for eating tree exudates. Here, we (1) describe qualitative phenotypic pelage differences between parental species and hybrids; (2) test whether significant quantitative differences exist between parental and hybrid morphometric phenotypes; and (3) determine which hybrid morphometic traits show heterosis, dysgenesis, trangression, or intermediacy relative to the parental trait. For morphometric traits, we investigated both cranial and post-cranial traits, particularly as most hybrid morphological studies focus on the former instead of the latter. Finally, we estimate mitogenomic distances between marmoset species from previously published data.

Results

Marmoset hybrid facial and overall body pelage variation reflected novel combinations of coloration and patterns present in parental species. In morphometric traits,C. jacchusandC. penicillatawere the most similar to each other, whileC. auritawas the most distinct, andC. geoffroyitrait measures fell between these other species. Only three traits inC. jacchusxC. penicillatahybrids showed heterosis. We observed heterosis and dysgenesis in several traits ofC. penicillataxC. geoffroyihybrids. Transgressive segregation was observed in hybrids ofC. auritaand the other species. These hybrids were alsoC. aurita-like for a number of traits. Genetic distance was closest betweenC. jacchusandC. penicillataand farthest betweenC. auritaand the other species.

Conclusion

We attributed significant morphometric differences between marmoset species to variable levels of morphological specialization for exudivory in these species. Our results suggest that intermediate or parental species-like hybrid traits relative to the parental trait values are more likely in crosses between species with relatively lesser genetic distance. More extreme phenotypic variation is more likely in parental species with greater genetic distance, with transgressive traits appearing in hybrids of the most genetically distant parental species. We further suggest that less developmental disturbances can be expected in hybrids of more recently diverged parental species, and that future studies of hybrid phenotypic variation should investigate selective pressures onCallithrixcranial and post-cranial morphological traits.