Strong Philopatry, Isolation by Distance, and Local Habitat Have Promoted Genetic Structure in Heermann’s Gull

Misael Daniel Mancilla-Morales,Exequiel Ezcurra,Andres Aguilar,Enriqueta Velarde,Araceli Contreras-Rodríguez,José G Soñanez-Organis,Enrico A Ruiz,Jesús A Rosas-Rodríguez

doi:10.3390/d14020108

Abstract

Philopatry can promote genetic differentiation among populations but remains undescribed in many seabirds. Hence, we explored such associations in Heermann’s Gull. Philopatry was observed monitoring 998 gulls in Rasa Island, while genetic differences were examined in the Cardonosa, Rasa, and Isabel islands using the cytochrome b of 296 gulls. Adults returned repeatedly to its natal valley or to a very close distance from it under different modelled hypotheses. Likewise, the interaction between sex and distance indicated significant male-biased philopatry. Besides, low to high genetic differentiation was observed between the Rasa and Cardonosa islands (ΦST = 0–0.22) (both in the Midriff Islands Region), but higher genetic differentiation against Isabel Island (ΦST > 0.25) (in the Mexican Province region). Consistently, genetic structure among regions was observed using different approaches (AMOVA: ΦCT = 0.49; SAMOVA: FCT = 0.49; and BAPS: K = 2). Similarly, a pattern of isolation by distance (rM = 0.82, p = 0.03), agrees with lower estimates of scaled migration rates between regions than among islands of the same region. Overall, it is suggested that the genetic structure found in Heermann’s Gull has been promoted by physical and behavioral barriers.

Highlights

Philopatry, sensu stricto, is the return of individuals to their natal site for breeding while dispersal is the opposite, and, in its original sense, a high degree of philopatry implies minimal gene flow [1,2,3]
68.34% of the individuals were faithful to their natal valley for breeding (n = 682 gulls), often returning to the same nesting site or only a few meters away
In Rasa Island, we found most of the haplotypes (h = 34), segregating sites (S = 40), and nucleotide differences (k = 0.88)

Summary

Introduction

Philopatry, sensu stricto, is the return of individuals to their natal site for breeding while dispersal is the opposite, and, in its original sense, a high degree of philopatry implies minimal gene flow [1,2,3]. Gene flow means individuals moving into and out of a population, influencing the partitioning of genetic variation among populations [4]. The pattern of movement of individuals can profoundly affect the genetic structure of populations; as generations go by, the fact that individuals are being born and breed in the same places should result in the formation of discrete populations, suggesting that the stronger the philopatry, the stronger the genetic structure [3,5]. To better describe the connection between dispersal and genetic structure, it is advised the combination of methods such as mark-recapture and molecular markers [5,11,12]

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Discussion

Conclusion