Data from: Can alternative mating tactics facilitate introgression across a hybrid zone by circumventing female choice?

Reproductive barriers and divergence in species’ mate recognition systems
underlie major models of speciation. However, hybridization between
divergent species is common, and classic mechanisms to explain permeable
reproductive barriers rarely consider how an individual may attain
reproductive success. Alternative mating tactics exist in various forms
across animal taxa. Such tactics may allow poorer quality individuals to
gain mating opportunities and facilitate introgression either through
asymmetrical positive selection, or by circumventing female choice
altogether in areas of secondary contact. One such tactic is satellite
behaviour in frogs, where silent males perch near advertisers in an
attempt to intercept females. To test whether such satellite male tactics
are context-dependent and favoured by hybrids, we genotyped and quantified
the morphology of 80 male spring peeper (Pseudacris crucifer) individuals
involved in caller-satellite associations from a secondary contact zone
between two intraspecific mitochondrial lineages. Irrespective of
population, satellite behaviour was best predicted by size but not body
condition. Within the contact zone, pure individuals showed a
significantly greater probability of being active callers, whereas hybrids
of one lineage were more likely to adopt the satellite tactic. We suggest
that satellite behaviour in P. crucifer promotes introgression,
breaks-down reproductive isolating barriers, and contributes to
asymmetrical introgression in this secondary contact zone. Alternative
mating tactics may thus be an underexplored but important alternative to
oft-discussed causes of genetic discordance found in hybrid zones.