Rape and the Prevalence of Hybrids in Broadly Sympatric Species: a Case Study using Albatrosses

Rohwer, Sievert; Harris, Rebecca B.; Walsh, H. E.

doi:10.7287/peerj.preprints.384

Cited by 3 publications

(4 citation statements)

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“…Moreover, the interval of 5 years between first sighting and first breeding was as expected; modal ages for these are 5 and 10 years, respectively, in Black-browed Albatrosses (Tickell 2000). Together with observations of heterospecific pairings elsewhere ( Table 1) it seems that only the hybridization between Black-footed and Laysan Albatross involves forced extra-pair copulations (Rohwer et al 2014). It is therefore important not to generalize from the well-studied situation in Hawaii as to the typical hybridization process in albatrosses, as in all other cases genuine mixedspecies partnerships were formed.…”

Section: Discussionmentioning

confidence: 92%

“…Back-crossing is therefore extremely rare unless the parental species are closely related; however, exceptions include hybrids between Northern Royal Albatross Diomedea sanfordi 9 Southern Royal Albatross Diomedea epomophora, formerly considered to be subspecies, which breed with Northern Royal Albatrosses at Taiaroa Head (Agreement on the Conservation of Albatrosses and Petrels 2009). In contrast, at Laysan Island (Hawaii), only one of five F1 hybrid Laysan 9 Black-footed Albatrosses observed in 2011 bred with a Laysan Albatross; however, there were several putative F2 backcrosses (Rutt 2013) and an F1 hybrid with a Laysan Albatross partner has successfully raised chicks on Midway since 2006 (Rohwer et al 2014).…”

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confidence: 99%

“…Hybridization in nature is predominantly unidirectional (Wirtz 1999). This also applies to the albatrosses; hybridization has only been verified between male Black-footed Albatrosses which force extra-pair copulations on female Laysan Albatrosses (Rohwer et al 2014), male Northern Royal and female Southern Royal Albatrosses (Robertson 1993) and, predominantly, male Black-browed Albatrosses T. melanophris and female Campbell Albatrosses Thalassarche impavida (Moore et al 2001). Here using molecular methods we verify hybrid chicks resulting from the pairing of a male White-capped Albatross Thalassarche steadi and a female Black-browed Albatross at South Georgia.…”

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Breeding‐site vagrancy and hybridization in albatrosses

Phillips

Cooper

Burg

2018

Ibis

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Given the rarity of hybridization in seabirds, which presumably relates to their very high philopatry, the degree of breeding‐site vagrancy should correspond with the incidence of mixed‐species pairing, although not necessarily with the production of hybrids if there are behavioural or genetic barriers to successful reproduction. Using molecular methods, we verified that two of the three chicks hatched by a vagrant male White‐capped Albatross Thalassarche steadi paired with a female Black‐browed Albatross Thalassarche melanophris at South Georgia were genuine hybrids (these chicks died before fledging, but a third chick – the result of an extra‐pair copulation – fledged successfully). In a wider review, we could find only five known or suspected mixed‐species pairs, and three different hybrids in albatrosses, mostly between closely related species. This appears to reflect behavioural barriers to hybridization in sympatric species and the low incidence of breeding‐site vagrancy (which mainly involves single individuals that invariably associate with the most phenotypically similar local taxon). Breeding‐site vagrancy is most frequent in the ‘shy‐albatross’ complex, which could explain why genetic divergence occurred more recently in this group than in other Thalassarche, and hence exploratory behaviour appears to be more important than numerical abundance or breeding distribution in driving colonization as well as hybridization processes in albatrosses.

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Section: Discussionmentioning

confidence: 92%

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Breeding‐site vagrancy and hybridization in albatrosses

Phillips

Cooper

Burg

2018

Ibis

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“…For instance, Black-footed Albatrosses (Phoebastria nigripes) were more successful in heterospecific rape attempts compared to Laysan Albatrosses (P. immutabilis), which probably resulted in asymmetric gene flow from Black-footed into Laysan Albatrosses (Rohwer et al, 2014). Forced copulations are also common in waterfowl (Mckinney et al, 1983), but a meta-analysis found more support for interspecific brood amalgamation than for forced copulations as a source for hybrids (Randler, 2005).…”

Section: Brood Amalgamation and Forced Copulationsmentioning

confidence: 99%

Crossing species boundaries : the hybrid histories of the true geese

Ottenburghs¹

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. Crossing Species Boundaries: The Hybrid Histories of the True Geese. PhD thesis, Wageningen University, the Netherlands. Hybridization, the interbreeding of different species, is a common phenomenon in birds: about 16% of bird species is known to have hybridized with at least one other species. Numerous avian hybrid zones have been studied from a morphological or genetic perspective, often documenting the interspecific exchange of genetic material by hybridization and backcrossing (i.e. introgression). The incidence of hybridization varies among bird orders with the Anseriformes (waterfowl: ducks, geese and swans) showing the highest propensity to hybridize. In this thesis, I provide a genomic perspective on the role of hybridization in the evolutionary history of one particular anseriform tribe, the Anserini or "True Geese", which comprises 17 species divided over two genera: Anser and Branta . The diversification of this bird group took place in the late Pliocene and the early Pleistocene (between four and two million years ago), conceivably driven by a global cooling trend that led to the establishment of a circumpolar tundra belt and the emergence of temperate grasslands. Most species show a steady population increase during this period, followed by population subdivision during the Last Glacial Maximum about 110,000 to 12,000 years ago. The combination of large effective population sizes and occasional range shifts facilitated contact between the diverging goose species, resulting in high levels of interspecific gene flow. Introgressive hybridization might have enabled these goose populations to quickly adapt to changing environments by transferring of advantageous alleles across species boundaries, increasing standing genetic variation or expanding phenotypic variation of certain traits (e.g., beak morphology). Hybridization seems to be a common and integral component in the evolution and diversification of geese. The pervasiveness of rapid speciation and hybridization in geese complicates the attempt to capture their evolutionary history in a phylogenetic tree, therefore I advocate a phylogenetic network approach. Indeed, trying to capture the complex diversification of the True Geese in a branching tree can be regarded as a wild goose chase. Abstract TABLE OF CONTENTS

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Male grey seal commits fatal sexual interaction with adult female harbour seals in the German Wadden Sea

Rohner

Hülskötter

Groß

et al. 2020

Sci Rep

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Males of several seal species are known to show aggressive copulating behaviour, which can lead to injuries to or suffocation of females. In the North Sea, grey seal predation on harbour seals including sexual harassment is documented and represents violent interspecific interaction. In this case series, we report pathological and molecular/genetic findings of 11 adult female harbour seals which were found dead in Schleswig-Holstein, Germany, within 41 days. Several organs of all animals showed haemorrhages and high loads of bacteria, indicating their septic spread. All females were pregnant or had recently been pregnant. Abortion was confirmed in three cases. Lacerations were seen in the uterus and vagina in six cases, in which histology of three individuals revealed severe suppurative inflammation with intralesional spermatozoa. Molecular analysis of vaginal swabs and paraffinembedded samples of the vagina identified grey seal DNA, suggesting violent interspecific sexual interaction with fatal outcome due to septicaemia. This is the first report of female harbour seals dying after coercive copulation by a male grey seal in the Wadden Sea. There are three main forms of how males sexually coerce females in animal societies: intimidation (punishment for denial of mating), harassment (increase of costs for females if they refuse to mate) and forced copulation (use of superior speed or physical strength to copulate with the female by force) 1. Sexual coercion is widely distributed among animal clades and seen in birds 2,3 , mammals 4,5 and invertebrates 6,7. Coercive behaviour of males reflects the competition for limited resources, in this case fertile females 8. It may be more common among species with polygynous mating systems 9 , including pinnipeds, where the dominance over a harem results in a substantial breeding reward for the male 10-12. Harassment and mating attempts can result in injuries to the females, such as bite wounds, mostly in the region of the face and the neck 12. Suffocation by being crushed by substantially larger males may even lead to death, as witnessed in New Zealand sea lions (Phocarctos hookeri) 13. Such aggression seen in adult male pinnipeds is usually focused on conspecifics and are mainly displayed in land breeding species like otariids and some phocids including grey seals (Halichoerus grypus) and elephant seals (Mirounga spp.) 14. Hybrids as the result of interspecific mating among sympatric species are not uncommon in the animal kingdom 15,16. Anatomical features and behavioural aspects including mate choice and reproductive competition may represent important limitations for such interspecies events 15,16. In most species, the female choice of a mating partner is considered to be a main factor to avoid hybridisation, reflecting their higher fitness and reproductive costs 16. In marine mammal polygynous mating systems though, the male dominates the mate choice, whereas the female contribution can be regarded as minor 17. Behavioural indicators for female receptivity in marine mamm...

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Rape and the Prevalence of Hybrids in Broadly Sympatric Species: a Case Study using Albatrosses

Cited by 3 publications

References 15 publications

Breeding‐site vagrancy and hybridization in albatrosses

Breeding‐site vagrancy and hybridization in albatrosses

Crossing species boundaries : the hybrid histories of the true geese

Male grey seal commits fatal sexual interaction with adult female harbour seals in the German Wadden Sea

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