Contrasting genetic structuring between colonies of the world's smallest penguin, Eudyptula minor (Aves: Spheniscidae)

The Little Penguin, Eudyptula minor, is a seabird that nests in colonies throughout New Zealand and southern Australia. Individuals from different colonies in southeast Australia differ significantly in morphology and ecology, suggesting that some genetic structuring may exist among colonies. In contrast, the marking of individuals with flipper bands has revealed some, albeit infrequent, movement between colonies. To determine the extent of genetic structuring, we tested the null hypothesis of substantial gene flow within southeast Australia by examining patterns of genetic variation across seven colonies separated by up to 1,500 km. Phylogeographic structuring was absent for mitochondrial control region sequences (2–3 individuals per colony). Microsatellite allele frequencies at five loci and mitochondrial haplotype frequencies (50 individuals per colony) were also homogenous among the majority of colonies sampled, although two colonies at the western periphery of the sampling range were distinct from those to the east. The genetic homogeneity among the majority of colonies can be explained by low but consistent contemporary gene flow among them, or a recent founder event in Bass Strait following the last marine transgression. The genetic break towards the western end of the sampling distribution appears best explained by differences in sea surface temperature and, consequentially breeding phenology, the latter hindering genetically effective migration.

Reverse ascertainment bias in microsatellite allelic diversity in owls (Aves, Strigiformes)

A rich source of markers may be overlooked by screening for polymorphism in the source species only. We screened 129 microsatellite loci isolated from the powerful owl (Ninox strenua) against two closely related species; Ninox  connivens and Ninox novaeseelandiae. From the screening effort 20 polymorphic markers were isolated, including six loci which were originally discarded as they were monomorphic in the source species. Further cross-species amplification of all 20 loci across species from two families, Strigidae and Tytonidae, revealed unusually high levels of polymorphism within closely related species, and limited success within phylogenetically distant species. Routine screening of multiple  species during the marker development phase can yield a wider range of  polymorphic markers which can subsequently enhance cross-species  amplification attempts.

Latitudinal gradients in abundance, and the causes of rarity in the tropics: a test using Australian honeyeaters (Aves: Meliphagidae)

Several studies have uncovered interspecific latitudinal gradients in abundance (population density) such that tropical species tend to be, on average, less abundant than species at higher latitudes. The causes of this relationship remain poorly studied, in contrast to the relative wealth of literature examining the relationship to latitude of other variables such as range size and body mass. We used a cross-species phylogenetic comparative approach and a spatial approach to examine three potential determining factors (distribution, reproductive output and climate) that might explain why abundance correlates with latitude, using data from 54 species of honeyeaters (Meliphagidae) in woodland environments in eastern Australia. There is a strong positive correlation between mean abundance and latitude in these birds. Reproductive output (clutch size) was positively linked to both abundance and latitude, but partial correlation analysis revealed that clutch size is not related to abundance once the effects of latitude are removed. A subsequent multiple regression model that also considered range size, clutch size and body mass showed that latitude is the only strong predictor of abundance in honeyeaters. In the separate spatial analysis, the climatic variables that we considered (temperature, rainfall and seasonality) were all strongly linked to latitude, but none served as a better predictor of abundance than latitude per se, either individually or collectively. The most intriguing result of our analyses was that the cross-species latitudinal pattern in abundance was not evident within species. This suggests an intrinsic cause of the pattern of ‘rarity in the tropics’ in Australian honeyeaters. We suggest that evolutionary age may provide a key to understanding patterns of abundance in these birds.

Determinants of local abundance in a major radiation of Australian passerines (Aves: Meliphagoidea)

Aim  To identify the factors that contribute to variation in abundance (population density), and to investigate whether habitat breadth and diet breadth predict macroecological patterns in a suborder of passerine birds (Meliphagoidea).
Location  Australia (including Tasmania).
Methods  Mean abundance data were collated from site surveys of bird abundance (the Australian Bird Count); range size and latitudinal position data from published distribution maps; and body mass and diet breadth information from published accounts. A diversity index of habitats used (habitat breadth) was calculated from the bird census data. We used bivariate correlation and multiple regression techniques, employing two phylogenetic comparative methods: phylogenetic generalized least squares and independent contrasts.

Results  Body mass and latitude were the only strong predictors of abundance, with larger-bodied and lower-latitude species existing at lower densities. Together, however, body mass and latitude explained only 11.1% of the variation in mean abundance. Range size and habitat breadth were positively correlated, as were diet breadth and body mass. However, neither range size, nor habitat breadth and diet breadth, explained patterns in abundance either directly or indirectly.
Main conclusions  Levels of abundance (population density) in meliphagoid birds are most closely linked to body mass and latitudinal position, but not range size. As with many other macroecological analyses, we find little evidence for aspects of niche breadth having an effect on patterns of abundance. We hypothesize that evolutionary age may also have a determining effect on why species tend to be rarer (less abundant) in the tropics.

A late Miocene-early Pliocene Mihirung bird (Aves: Dromornithidae) from Victoria, southeast Australia

An incomplete tarsometatarsus identified as an indeterminate species of Dromornithidae is described from the upper Miocene–lower Pliocene shallow marine Black Rock Sandstone at Beaumaris, Victoria, Australia. This isolated specimen represents one of the few pre-Pleistocene dromornithids with a well-constrained geologic age. Additionally, it is one of the few pre-Quaternary dromornithid fossils recorded from southeast Australia. Comparisons with known dromornithid taxa suggest that the Beaumaris dromornithid is distinct from previously
established species. This hitherto unknown species of dromornithid in the late Neogene of southeastern Australia cautions against deriving evolutionary patterns solely on the basis of fossils from northern Australia.

Isolation and characterisation via 454 sequencing of microsatellites from the tawny frogmouth, Podargus strigoides (Class Aves, Family Podargidae)

We isolated 24 novel polymorphic microsatellite markers from the tawny frogmouth, a nocturnal bird endemic to Australia, which has successfully adapted to urban environments. Initially, 454 shotgun sequencing was used to identify 733 loci with primers designed. Of these, we trialled 30 in the target species of which all amplified a product of expected size. Subsequently, all 30 of these loci were screened for variation in 25 individuals, from a single population in Melbourne, Victoria, Australia. Twenty-eight loci were polymorphic with observed heterozygosity ranging from 0.03 to 0.96 (mean 0.58) and the number of alleles per locus ranged from 2 to 18 (average of 6.5); we confirmed that 24 loci conformed to Hardy–Weinberg expectations. The 24 loci identified here will be sufficient to unequivocally identify individuals and will be useful in understanding the reproductive ecology, population genetics and the gene flow amongst localities in urban environments where this bird thrives.

Microsatellite markers characterized in the barn owl (Tyto alba) and of high utility in other owls (Strigiformes: AVES)

We have identified 15 polymorphic microsatellite loci for the barn owl (Tyto alba), five from testing published owl loci and 10 from testing non-owl loci, including loci known to be of high utility in passerines and shorebirds. All 15 loci were sequenced in barn owl, and new primer sets were designed for eight loci. The 15 polymorphic loci displayed two to 26 alleles in 56–58 barn owls. When tested in 10 other owl species (n = 1–6 individuals), between four and nine loci were polymorphic per species. These loci are suitable for studies of population structure and parentage in owls.

Does behavior reflect phylogeny in swiftlets (Aves: Apodidae)? A test using cytochrome b mitochondrial DNA sequences

Swiftlets are small insectivorous birds, many of which nest in caves and are known to echolocate. Due to a lack of distinguishing morphological characters, the taxonomy of swiftlets is primarily based on the presence or absence of echolocating ability, together with nest characters. To test the reliability of these behavioral characters, we constructed an independent phylogeny using cytochrome b mitochondrial DNA sequences from swiftlets and their relatives. This phylogeny is broadly consistent with the higher classification of swifts but does not support the monophyly of swiftlets. Echolocating swiftlets (Aerodramus) and the nonecholocating "giant swiftlet" (Hydrochous gigas) group together, but the remaining nonecholocating swiftlets belonging to Collocalia are not sister taxa to these swiftlets. While echolocation may be a synapomorphy of Aerodramus (perhaps secondarily lost in Hydrochous), no character of Aerodramus nests showed a statistically significant fit to the molecular phylogeny, indicating that nest characters are not phylogenetically reliable in this group.