Laura M. Stenzler

Congruent population structure inferred from dispersal behaviour and intensive genetic surveys of the threatened Florida scrub‐jay (Aphelocoma cœrulescens)

The delimitation of populations, defined as groups of individuals linked by gene flow, is possible by the analysis of genetic markers and also by spatial models based on dispersal probabilities across a landscape. We combined these two complimentary methods to define the spatial pattern of genetic structure among remaining populations of the threatened Florida scrub‐jay, a species for which dispersal ability is unusually well‐characterized. The range‐wide population was intensively censused in the 1990s, and a metapopulation model defined population boundaries based on predicted dispersal‐mediated demographic connectivity. We subjected genotypes from more than 1000 individual jays screened at 20 microsatellite loci to two Bayesian clustering methods. We describe a consensus method for identifying common features across many replicated clustering runs. Ten genetically differentiated groups exist across the present‐day range of the Florida scrub‐jay. These groups are largely consistent with the dispersal‐defined metapopulations, which assume very limited dispersal ability. Some genetic groups comprise more than one metapopulation, likely because these genetically similar metapopulations were sundered only recently by habitat alteration. The combined reconstructions of population structure based on genetics and dispersal‐mediated demographic connectivity provide a robust depiction of the current genetic and demographic organization of this species, reflecting past and present levels of dispersal among occupied habitat patches. The differentiation of populations into 10 genetic groups adds urgency to management efforts aimed at preserving what remains of genetic variation in this dwindling species, by maintaining viable populations of all genetically differentiated and geographically isolated populations.

Syllable type consistency is related to age, social status and reproductive success in the tropical mockingbird

Many animals repeat standardized displays multiple times while attracting a mate or deterring a rival. In such contexts it is possible that the ability to perform each display or signal type in a consistent fashion is under direct selection. Studies on sexual selection on song learning in birds have focused on differences in repertoire size with less attention to the potential importance of being able to perform each song/syllable type with high consistency. We present evidence that tropical mockingbirds decrease the variation between renditions of each syllable type as they grow older (i.e., become more consistent) and that more consistent males in this species tend to have higher dominance status and reproductive success. These findings stress the importance of consistency in the performance of sexual displays and suggest that this parameter may be very relevant even in species that are selected for high vocal diversity (i.e., large repertoires). In addition to signalling dominance status and age, we hypothesize that syllable type consistency may also be an indicator of the integrity of brain function in birds analogous to the tests used for neuropsychological assessment in humans.

Avian host DNA isolated from the feces of white-winged vampire bats (Diaemus youngi)

Studies on the feeding ecology of vampire bats (Phyllostomidae: Desmodontinae) have been limited by the diagnostic techniques available for identifying host taxa. A precipitin-based test has been the standard method for determining their domestic host preferences (e.g., Cardoso, 1995). This postmortem immunological assay provides a presence or absence indication of a particular host’s blood in a vampire bat’s gut contents (Greenhall, 1970). However, the precipitin test has significant limitations. The bat must be sacrificed for its stomach sample, a particular difficulty for the rare species Diaemus youngi and Diphylla ecaudata. The precipitin test has low utility for identifying wild hosts (Greenhall, 1970), as it requires the harvesting of antibodies, usually in rabbits, using serum collected from all potential host organisms. For this reason, antibody techniques are generally considered too costly (time-wise and financially) for investigating a diverse potential prey range (Symondson, 2002). Indeed, harvesting antibodies of all the potential sympatric avian host species of a vampire bat would be unfeasible. Third, cross-reactivity among related host taxa is expected, and the precipitin technique is therefore unlikely to be diagnostic at the level of families or genera. An alternative and potentially powerful approach is to use the host DNA as a marker for host identification. Although previous studies demonstrate that prey DNA can be isolated and amplified via PCR from feces (Hoss et al., 1992; Sutherland, 2000; Jarman et al., 2002, 2004; Jarman and Wilson, 2004; Deagle et al., 2005) and even fossilized feces (e.g., Kuch et al., 2002), vampire bat fecal samples are a uniquely implausible PCR template due to the lack of robust tissue and very high concentration of PCR-inhibiting heme compounds. The resistance of prey tissue to digestion is a factor determining the extent to which the targeted fecal DNA is degraded (Jarman et al., 2004). Past successful PCR-based Acta Chiropterologica, 8(1): 255–274, 2006 PL ISSN 1508-1109

Isolation and characterization of microsatellite markers from the white-ruffed manakin Corapipo altera (Aves, Pipridae).

We describe 15 polymorphic microsatellite loci from the white‐ruffed manakin Corapipo altera, a common understory bird of Neotropical lowland and montane evergreen forests from eastern Honduras to northwestern Colombia. These markers were developed in order to assess population structure and genetic diversity in a fragmented landscape, and to study gene flow between forest fragments. Primers were tested on a population of 159 individuals from the Coto Brus region of southwestern Costa Rica. We found between four and 23 alleles per locus, and observed heterozygosities ranging from 0.23 to 0.93.

Isolation and characterization of microsatellite markers from three species of swallows in the genus Tachycineta: T. albilinea, T. bicolor and T. leucorrhoa.

We describe 30 microsatellite loci developed from three species of swallows in the genus Tachycineta: T. bicolor (tree swallow), T. albilinea (mangrove swallow), and T. leucorrhoa (white‐rumped swallow). These commonly studied birds nest in secondary cavities and are distributed from Alaska to Argentina. Primer pairs were designed for each species individually and tested for cross‐amplification in 40–48 individuals of all three species. Polymorphism ranged from 5 to 65 alleles per locus (mean = 19.1). These markers will allow comparative studies of extra‐pair paternity rates among members of the genus as well as the assessment of population structure.

Isolation and characterization of microsatellite markers from the acacia‐ant Crematogaster mimosae

We describe 10 microsatellite loci developed from Crematogaster mimosae, an ant species that nests mutualistically in Acacia drepanolobium trees in east Africa. Polymorphism ranged from 4 to 16 alleles per locus (mean = 7.3). Observed and expected heterozygosities ranged from 0.485 to 0.813 (mean 0.626), and from 0.502 to 0.894 (mean 0.674), respectively. These markers will foster studies of the population structure, colony structure, and reproductive strategies of these ants.